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https://www.ericcointernational.com/gnss-board/full-system-full-frequency-point-high-precision-positioning-directional-board.html

Full System Full Frequency Point High Precision Positioning Directional Board

ER-GNSS-B01 is a new generation of compact high-precision positioning and orientation board based on NebulasIV RF baseband integrated chip, which supports full-frequency high-precision positioning and orientation of the whole system. Supports BDS B1I/B2I/B3I, GPS L1/L2/L5, GLONASS L1/L2, Galileo E1/E5a/E5b, QZSS L1/L2/L5, SBAS and other satellite signals.The ER-GNSS-B01 comes in a small classic size and is compatible with the previous generation of mainstream boards. It is mainly used in UAV, precision agriculture, intelligent driving and other application fields.

Features

Based on the latest generation of Nebulas IV RF baseband and RTK algorithm integrated GNSS SoC chip, 1408 channels

71 x 46mm board, universal size, interface compatible with previous generation board

Support the whole system full frequency point on chip RTK positioning solution, and double antenna orientation solution

Support BDS B1I/B2I/B3I, GPS L1/L2/L5, GLONASS L1/L2, Galileo E1/E5a/E5b, QZSS L1/L2/L5, SBAS

Dual-RTK, Dual RTK engine technology

https://www.ericcointernational.com/application/advancements-in-deformation-monitoring-utilizing-gnss-technology.html

In recent years, the field of deformation monitoring has witnessed significant advancements, largely driven by the widespread adoption of Global Navigation Satellite System (GNSS) technology. This technology, originally developed for navigation and positioning applications, has found extensive use in various fields, including geodesy, surveying, and deformation monitoring. This article explores how GNSS technology, when applied to deformation monitoring, brings about innovation and efficiency.

1.What is GNSS Monitoring?

Every time you open your phone's map navigation or hear the voice prompt "turn right in 500 meters" while driving, you may not realize that it all relies on it.

GNSS, the Global Navigation Satellite System, including Beidou and GPS, is widely used in geodesy, deformation monitoring, and other fields due to its all-weather and high-precision characteristics. GNSS monitoring technology tracks real-time deformations and displacements of large-scale engineering projects, assesses building safety and operational conditions, reduces workload, and achieves unmanned operations.

Deformation monitoring refers to the continuous observation and analysis of changes in the shape, position, or size of objects or surfaces over time. It plays a crucial role in various engineering and geoscience applications, such as monitoring the stability of structures, assessing geological hazards, and studying tectonic movements.

Fig.1 GNSS monitoring in several fields

Fig.1 GNSS monitoring in several fields

Based on this technology, deformation monitoring GNSS receivers designed for complex environmental monitoring integrate Beidou/GNSS technology, with characteristics such as high adaptability, stability, easy deployment, easy maintenance, and low power consumption.

One of the key advantages of GNSS technology in deformation monitoring is its ability to provide accurate and precise positioning data in real-time. GNSS receivers, equipped with multiple satellite antennas, can track signals from a constellation of satellites orbiting the Earth. By processing these signals, GNSS receivers can determine the receiver's position with high accuracy, typically within a few centimeters.

2.GNSS Empowers Precise Deformation Monitoring Technology

Deformation monitoring involves continuous observation and analysis of changes in object shape. To accurately predict deformation trends, a real-time, high-precision monitoring system is required, and GNSS technology meets this demand. The monitoring principle of this system is to automatically monitor surface displacements of dams using GNSS, receiving GPS signals in real-time and transmitting them to the control center. Server software processes the data, determining the three-dimensional coordinate changes of each monitoring point and issuing alarms based on preset warning values.

3.Cloud Empowerment: Achieving Efficient Deformation Monitoring Platforms

The deformation monitoring GNSS cloud monitoring platform integrates the Global Navigation Satellite System and cloud computing technology, providing real-time monitoring and data analysis services. GNSS receivers deployed on targets acquire accurate position and time data, which are processed and analyzed by cloud servers. The platform boasts high data stability, compatibility with various sensors, strengthened communication stability, and millimeter-level perception of subtle changes.

Fig.2 GNSS in Deformation Monitoring Platforms

Fig.2 GNSS in Deformation Monitoring Platforms

Its visualization monitoring function provides clear information on monitoring points and overall situations. Cloud access is convenient without requiring software installation, thereby enhancing operational efficiency. Additionally, the platform supports various warning modes, offering comprehensive online monitoring and alert services.

4.Exploring the Superior Performance of GNSS in Deformation Monitoring

High Integration: Integrates GNSS, sensors, and other functions into one unit, making installation and maintenance simple.
Ultra-Low Power Consumption: Continuous operation consumes less than 1.5W, reducing the need for solar power supply and saving costs.
All-Weather Monitoring: Unaffected by weather conditions, equipped with lightning protection facilities for long-term all-weather observation, suitable for flood control, geological disasters, and other fields.
High Precision Monitoring: GNSS provides high-precision relative positioning, with practical deformation monitoring accuracy reaching ±(0.5-2)mm.
High Stability: Average fault-free time exceeds 30,000 hours, with high protection level and anti-interference capability.
Integrated with Cloud: Automatically connects to the platform for remote control, batch upgrades, and online maintenance, improving operational efficiency.
Intelligent Integration: Built-in sensors achieve multi-mode intelligent switching, supporting various external sensors to meet different monitoring needs.

5.Summary

Ericco not only provides inertial sensors but also offers high-precision GNSS products, such as the ER-GNSS-C01/02 GNSS chip with a hot start time of <1s and a cold start time of <29s; ER-GNSS-R03 receiver, achieving centimeter-level positioning, and supporting BDS, GPS, GLONASS, Galileo, QZSS, SBAS.

https://www.ericcointernational.com/application/optimizing-drilling-efficiency-q-flex-accelerometers-combined-with-other-sensors.html

In the realm of modern drilling operations, efficiency reigns supreme. As the oil and gas industry continues to evolve, the demand for enhanced drilling techniques that maximize productivity while minimizing costs has never been greater. Enter Q-Flex accelerometers, revolutionizing drilling efficiency through their seamless integration with a diverse array of sensors.

1.Enhancing Drilling Dynamics with Q-Flex Accelerometers

One of the key benefits of combining Q-Flex accelerometers with other sensors is the ability to gain a holistic view of drilling dynamics. By integrating accelerometers with gyroscopes, for instance, operators can track both linear and angular motion with unparalleled accuracy. This comprehensive motion tracking capability enables precise control over drilling parameters, such as toolface orientation and wellbore trajectory, leading to more efficient drilling operations.

Dynamic Drilling Optimization: Accelerometers, when integrated with advanced data analytics and machine learning algorithms, contribute to real-time drilling optimization efforts. By continuously monitoring drilling parameters and analyzing vibration data, these systems identify inefficiencies, predict equipment failures, and recommend adjustments to enhance drilling performance.

Fig.1.

When integrated into drilling control systems, accelerometers provide real-time feedback for regulating parameters such as rotational speed, axial force, and torque. By precisely measuring acceleration and vibration levels, these sensors facilitate adjustments that optimize drilling performance and prevent equipment damage.

Moreover, when Q-Flex accelerometers are paired with pressure sensors, temperature gauges, and flow meters, a wealth of additional information becomes available. This multidimensional data allows operators to monitor drilling fluid properties, detect formation changes in real-time, and optimize mud circulation for improved wellbore stability.

2.Safeguarding Operations: Q-Flex Accelerometers and Sensor Fusion

In addition to optimizing drilling performance, the combined use of Q-Flex accelerometers and other sensors plays a crucial role in enhancing safety. By continuously monitoring drilling parameters and environmental conditions, these sensors can detect anomalies and potential hazards before they escalate into safety incidents. Automatic shutdown systems triggered by sensor data provide an added layer of protection for personnel and equipment alike. They detect abnormal vibrations or shocks, triggering automatic shutdowns or alarms to prevent accidents and ensure personnel safety.

The integration of accelerometers with advanced imaging sensors, such as electromagnetic or acoustic sensors, offers invaluable insights into subsurface geology. By correlating vibration data with imaging data, geologists can accurately map reservoir structures and identify potential drilling hazards, ultimately reducing drilling risks and enhancing well productivity.

Fig.2 Hole drilling

3.Specific instrument with Accelerometer-- North Seeker

The North Seeker typically consists of a gyroscope, which measures the rotation of the Earth, and accelerometers, which measure the effects of gravity. By combining data from these sensors with sophisticated algorithms, the North Seeker accurately determines the azimuthal direction of true north, regardless of magnetic interference.

In drilling applications, North Seekers are essential for directional drilling operations, where precise wellbore trajectory control is required. By providing accurate azimuthal information, North Seekers enable operators to steer the drill bit along the desired path, optimizing well placement and maximizing reservoir recovery.

In systems like North Seekers, accelerometers, together with gyroscopes and north-seeking algorithms, play a critical role. They aid in precise motion tracking, enabling accurate determination of the azimuthal direction of true north. This is essential for directional drilling, enhancing survey accuracy, reducing survey time, and improving adaptability to challenging drilling environments.

4.Summary
In conclusion, the synergy between Q-Flex accelerometers and other sensors represents a paradigm shift in drilling efficiency and safety. By harnessing the power of multidimensional data, operators can optimize drilling processes, mitigate risks, and unlock new frontiers in energy exploration and production. As technology continues to advance, the integration of sensors will undoubtedly remain at the forefront of innovation in the quest for greater efficiency and sustainability in drilling operations.

It is notable that Ericco provides high-precision quartz accelerometers, such as the ER-QA-01A3, with a bias stability of 10μg, scale factor repeatability of 10ppm, and a weight of 80g, which can be widely used in aircraft carrier microgravity measurement systems, inertial navigation systems, and static angle measurement systems.

https://www.ericcointernational.com/application/how-to-enhance-bias-stability-of-q-flex-accelerometers.html

Q-Flex accelerometers have revolutionized various industries, from aerospace to automotive, due to their compact size, high precision, and low power consumption. However, maintaining bias stability, which is crucial for accurate and reliable measurements, remains a challenge. In this article, we delve into effective strategies to enhance the bias stability of Q-Flex accelerometers, ensuring optimal performance across diverse applications.

1.What is Bias Stability:
Bias stability refers to the accelerometer's ability to maintain consistent output in the absence of any acceleration input. Even minor fluctuations in bias can lead to significant errors in measurements over time. Factors such as temperature variations, mechanical stress, and electronic noise can influence bias stability, necessitating proactive measures for mitigation.

2.Measures to Improve Bias Stability
2.1 Improvement of Flexure Quartz Material
The flexure is a key component of quartz flexure accelerometers, and its performance and quality play a crucial role in the technical performance indicators of quartz flexure accelerometers. The performance and quality of the flexure largely depend on the quartz material used to manufacture it.

https://www.ericcointernational.com/wp-content/uploads/2024/04/Fig.1-Testing-machine-for-accelerometers-300x300.jpeg
Fig.1 Testing machine for accelerometers

Advanced testing methods can be utilized to further analyze the various indicators of the material. Through processing the flexure and testing the performance of the quartz flexure accelerometer, the impact of quartz material on the performance of the quartz flexure accelerometer can be verified. This process helps determine the technical performance requirements of quartz flexure accelerometers for quartz glass.

2.2 Reduction of Assembly Stress Impact
The basic structure of the mechanical head of a quartz flexure accelerometer involves clamping the pendulum assembly between the upper and lower excitation rings, with the diaphragm belt connecting them through adhesive bonding and other methods. However, using adhesive bonding can result in poor wetting between the adhesive and the metal material, low adhesion, and low bonding strength, compounded by factors such as unstable raw material composition.

To address this issue, laser welding can be employed. Based on the structure and material characteristics of quartz flexure accelerometers, a low-power solid-state laser welding machine is selected for welding the core.

Compared to adhesive bonding, laser welding is a rigid connection method. The stiffness of the connection in laser welding is much greater than that in adhesive bonding. Rigid connection can greatly reduce the tiny movements of the upper and lower excitation rings relative to the quartz flexure pendulum assembly, as well as the deformation at the interface between the excitation ring and the quartz flexure pendulum assembly. It also eliminates the inherent plastic deformation of organic materials like adhesives, thereby enhancing the stability of the head structure.

https://www.ericcointernational.com/wp-content/uploads/2024/04/Fig.2-A-Laser-Bonder.jpg
Fig.2 A Laser Bonder

2.3 Noise Reduction:
Electronic noise can adversely affect the bias stability of Q-Flex accelerometers, particularly at low acceleration levels. Implementing noise reduction techniques such as signal averaging, filtering, and shielded cabling can attenuate unwanted noise sources, improving the signal-to-noise ratio and enhancing bias stability, especially in high-noise environments.

2.4 Thermal Management:
Temperature fluctuations pose a significant challenge to bias stability in Q-Flex accelerometers. Implementing effective thermal management solutions is paramount to minimize the impact of temperature variations. This includes employing temperature sensors for real-time monitoring, implementing temperature compensation algorithms, and utilizing thermal insulation techniques to shield the sensor from external heat sources.

3.Summary

Enhancing the bias stability of Q-Flex accelerometers is critical for ensuring accurate and reliable measurements in diverse applications. By implementing a combination of calibration techniques, thermal management solutions, mechanical design considerations, and noise reduction strategies, manufacturers and users can optimize bias stability and unlock the full potential of Q-Flex accelerometers across various industries.

Ericco provides high-precision quartz accelerometers, such as the ER-QA-01A3, with a bias stability of 10μg, scale factor repeatability of 10ppm, and a weight of 80g, which can be widely used in aircraft carrier microgravity measurement systems, inertial navigation systems, and static angle measurement systems.

https://www.ericcointernational.com/application/small-size-big-impact-gnss-chips-aid-in-monitoring-landslide.html
Landslides are complex geological phenomena influenced by various factors such as slope instability, weather conditions, and human activities. Monitoring these hazards is crucial for early detection and mitigation efforts to protect lives and infrastructure. GNSS technology, specifically its integration with monitoring equipment using GNSS chips, which relies on signals from satellite constellations to determine precise locations on Earth's surface, has emerged as a valuable tool for landslide monitoring.

1.The Role of GNSS Chips in Landslide Monitoring

Cost Reduction: GNSS chips serve as the core components of GNSS receivers used in landslide monitoring equipment. These chips have significantly reduced the cost of monitoring devices, making them more accessible for widespread deployment in landslide-prone areas. The affordability of GNSS chips has democratized access to advanced monitoring technology, enabling researchers, governments, and communities to implement proactive measures against landslide risks.

Miniaturization: The small size of GNSS chips allows for the development of compact and lightweight monitoring devices. These devices can be easily deployed in remote and inaccessible terrain, providing continuous monitoring of landslide-prone areas without the need for extensive infrastructure or manpower. The miniaturization of monitoring equipment enhances scalability and flexibility, enabling targeted monitoring efforts in high-risk zones.

Fig.1 Small GNSS Chip developed by Ericco WLCSP 1.70×2.84×0.5mm

Enhanced Performance: Despite their compact size, GNSS chips offer high-performance capabilities in terms of signal acquisition, tracking sensitivity, and data accuracy. Advanced signal processing algorithms embedded in GNSS chips ensure reliable positioning information, even in challenging environmental conditions such as dense vegetation or adverse weather. The enhanced performance of GNSS chips enables more accurate and timely detection of landslide-induced deformations, allowing for early warning and response measures to be implemented effectively.

2.Advancements in GNSS Chip Technology

Multi-Frequency Support: The latest generation of Ericco GNSS chips (show in Fig.1) supports multi-frequency signals from satellite constellations, including GPS, GLONASS, Galileo, and BeiDou. Multi-frequency receivers offer improved resilience to signal interference and multipath effects, enhancing the accuracy and reliability of landslide monitoring data. These chips enable precise positioning and deformation measurements, allowing researchers to capture subtle changes in landslide behavior with greater sensitivity.

Integration with Sensor Networks: GNSS chips can be integrated with other sensor technologies, such as accelerometers and inclinometers, to create multi-sensor monitoring networks for comprehensive landslide analysis. By combining GNSS data with data from other sensors, researchers can gain deeper insights into the mechanisms driving landslide activity and improve the accuracy of hazard assessment models. The integration of GNSS chips with sensor networks enhances the robustness and versatility of landslide monitoring systems, enabling holistic approaches to landslide risk management.

Fig.2 Landslide monitoring with GNSS technology

Fig.2 Landslide monitoring with GNSS technology

3.Challenges and Future Directions

Data Quality and Processing: Despite advancements in GNSS chip technology, challenges remain in ensuring the quality and reliability of monitoring data, particularly in harsh environmental conditions or areas with limited satellite visibility. Efforts are underway to develop robust data processing algorithms and quality control measures to address these challenges and improve the accuracy of landslide monitoring results.

Operational Considerations: The deployment and maintenance of GNSS monitoring networks require careful planning and coordination to ensure optimal coverage and data continuity. Operational challenges such as power supply, data transmission, and equipment durability need to be addressed to maximize the effectiveness of landslide monitoring efforts. Innovations in renewable energy sources, wireless communication technologies, and ruggedized monitoring equipment are helping to overcome these operational challenges and enhance the resilience of monitoring networks.

4.Conclusion
GNSS chips have revolutionized landslide monitoring by offering cost-effective, compact, and high-performance solutions for continuous deformation monitoring. These chips have enabled researchers and practitioners to implement proactive measures for landslide risk reduction, contributing to the safety and resilience of communities in landslide-prone areas.

It's worth noting that the ER-GNSS-C01/02 chip developed by Ericco has WLCSP dimensions of 1.70×2.84×0.5mm, with a data update rate of 1Hz, and a capture sensitivity of -147dBm and tracking sensitivity of -160dBm. Currently, the chip shows good performance in terms of volume, power consumption, and signal acquisition and tracking. The integration of GNSS nano-chip technology with RF baseband processing integration can effectively reduce the cost of GNSS monitoring equipment while also shrinking the device size, which is an important step in promoting the widespread application of GNSS monitoring devices in landslide hazard monitoring.

Testing Methods for Quartz Flexure Accelerometers - Ericco Inertial System [ericcointernational.com]

Small Size Quartz Accelerometer For Aerospace
Quartz flexure accelerometers stand at the forefront of precision sensing technology, renowned for their exceptional accuracy, stability, and reliability. These qualities render them indispensable across a multitude of industries, where precise acceleration measurements are not just desired but paramount. From the rigorous demands of aerospace to the dynamic environments of automotive engineering, and from seismic monitoring to the intricacies of industrial automation, quartz flexure accelerometers serve as vital instruments for data acquisition, analysis, and safety assurance.

The pivotal role of these accelerometers underscores the necessity for thorough testing methods to validate their performance and ensure their efficacy in real-world applications. In this article, we embark on an in-depth exploration of the testing procedures and criteria essential for the comprehensive evaluation of quartz flexure accelerometers.

1.Testing Procedures for Quartz Flexure Accelerometers
(1) Place the quartz flexure accelerometer horizontally on the experimental platform in the stationary state of the vibration table, connect it to the power supply, and connect the output terminal to an oscilloscope. Record the output signal on the oscilloscope and observe its amplitude characteristics. This represents the output signal of the quartz flexure accelerometer without vibration.

(2) Keep the accelerometer in its original position, select the vertical fixed-frequency mode for the vibration table, set the frequency to 30Hz, and the intensity to 20%. Record the output signal on the oscilloscope again.

(3) Increase the frequency while maintaining a constant intensity of 20% in the vertical fixed-frequency mode of the vibration table. Record and observe the changes in the output signal of the accelerometer at frequencies of 30Hz, 35Hz, 40Hz, 45Hz, and 50Hz.

(4) Under the vertical fixed-frequency mode of the vibration table with a constant frequency of 40Hz, increase the intensity and record the changes in the output signal of the accelerometer. Record the output signal at intensities of 5%, 15%, 25%, and 35%.

Fig.1 High Performance Quartz Accelerometer

Fig.1 ER-QA-03A High Performance Quartz Accelerometer

(5) Change the vibration mode, set horizontal fixed frequency, and longitudinal fixed frequency modes, repeating steps (2), (3), and (4) to record the second and third sets of data.

(6) Perform spectrum analysis on the output signals of the accelerometer under three different conditions of changing frequency, intensity, and vibration mode to study the vibration characteristics of the quartz flexure accelerometer.

2.Testing Criteria and Standards
The performance and accuracy of quartz accelerometers directly affect the accuracy and reliability of test results, necessitating rigorous testing. Below are some common testing criteria and standards:

(1) Acceleration Response: It refers to the sensitivity of the quartz accelerometer to changes in acceleration, usually tested using a step function signal. The stability and accuracy of the test system should be noted, and appropriate acceleration ranges and sampling rates should be selected based on test requirements.

(2) Second Harmonic Distortion: It refers to the ratio of the amplitude of the second harmonic signal to the fundamental signal in the acceleration signal, usually expressed as a percentage. The second harmonic distortion of quartz accelerometers should be less than 5% to ensure the accuracy of test results.

Fig.2 Aerospace Quartz Accelerometer

Fig.2 ER-QA-01A Aerospace Quartz Accelerometer

(3) Bias Stability: It refers to the stability of the output signal of the quartz accelerometer during long-term testing, usually measured in zero drift or percentage. Quartz accelerometers are required to have a bias stability of less than 1% to ensure the reliability of test results.

These are some of the testing criteria and standards for quartz accelerometers, and the selection should be made based on specific requirements and application scenarios during actual testing.

3.Conclusion
In conclusion, testing methods play a crucial role in validating the performance and reliability of quartz flexure accelerometers. By thoroughly understanding and strictly adhering to these standards, the accuracy and reliability of test results can be improved, providing robust assurance for testing work.

Ericco not only provides high-precision quartz flexure accelerometers, such as ER-QA-03A (Bias repeatability: 10-50μg) and ER-QA-01A (Bias repeatability: 10μg), but also offers detailed testing and installation methods, as well as professional inertial solutions.

Fig.1 Triaxial Quartz Accelerometer.
In various industries, such as aerospace, automotive, and robotics, there is a need to precisely measure the inclination angle of objects. Triaxial accelerometers play a crucial role in fulfilling this requirement. This article delves into the fundamentals of triaxial accelerometers to gain a deeper understanding of their functionality and applications.

Whether it's in the inertial measurement systems of space vehicles, the inclination measurement of vehicles and ships, the balance attitude detection of robots, or the limb posture detection in medical applications, these sensors utilize MEMS technology to measure inclination angles effectively. Notably, they offer advantages such as small size, light weight, affordability, and minimal interference with the mechanical mechanisms of the objects being measured.

1.Types of Acceleration Sensors
There are three main types of acceleration sensors: piezoelectric, capacitive and thermal. Classified by the number of input axes, there are single-axis, dual-axis and triple-axis accelerometers. Each of these has their own advantages. Take the technical principle of capacitive triaxial accelerometer as an example.

Capacitive accelerometers can sense motion conditions such as acceleration or vibration in different directions. It is mainly a movable mechanism designed using the mechanical properties of silicon. The mechanism mainly includes two sets of silicon comb teeth, when one is fixed, and the other is moved immediately; the former is equivalent to a fixed electrode, and the latter is a movable electrode. When the movable comb teeth are displaced, there will be a change in capacitance proportional to the displacement.

Triaxial accelerometers are actually 3 distinct accelerometers mounted in the orthogonal X, Y, and Z directions. Integrated packaging brings all 3 accelerometers into a single cube with a single cable harness and overall 3–to–1 reduction in cabling.

Fig.1 Triaxial Quartz Accelerometer.

2.How does a triaxial accelerometer work?
Most of the three-axis accelerometers use piezoresistive, piezoelectric and capacitive working principles. The resulting acceleration is proportional to the changes in resistance, voltage and capacitance, and is collected through corresponding amplification and filter circuits. This is based on the same principle as an ordinary accelerometer, so in a certain technology three single-axis can become a three-axis.

Since the three-axis accelerometer is also based on the principle of gravity, the three-axis accelerometer can realize the double-axis plus and minus 90 degrees or the acceleration generated by the double-axis three-axis proportional to the change of resistance, voltage and capacitance, and is collected through the corresponding amplification and filter circuit.

Triaxial accelerometers have measurement bandwidths (up to 15 kHz) for condition monitoring of critical machine operations. It works on the basis of acceleration. Acceleration is a space vector. On the one hand, to accurately understand the motion state of an object, the components on its three coordinate axes must be measured; the acceleration signal must be detected.

Fig.2 three axis accelerometer principle

3.Application of Triaxial Accelerometer
Automotive: In the automotive industry, triaxial accelerometers are integrated into vehicles for stability control systems, rollover detection, crash sensing, and impact detection. They play a crucial role in enhancing vehicle safety by detecting sudden changes in acceleration and triggering appropriate safety measures such as airbag deployment.

Industrial Monitoring: Triaxial accelerometer sensors offer data insights enhancing efficiency and utilization of industrial machinery. Embedded 3-axis accelerometers excel in monitoring machine health, necessitating attributes like wide bandwidth, compact size, low power consumption, and consistent performance.

Robotics: Triaxial accelerometers are essential components in robotic systems for balance and motion control. They enable robots to detect changes in acceleration and orientation, allowing for precise movement and navigation in dynamic environments.

Structural Health Monitoring: Biaxial accelerometers typically meet requirements adequately for many sensor applications. Yet, specific contexts demand three-axis accelerometers, notably in data mining equipment, valuable asset monitoring, collision detection, and measuring vibrations in large-scale structures such as buildings and wind turbines. They measure vibrations and dynamic loads, providing valuable data for assessing structural stability and detecting potential defects or damage.

Fig.3 Triaxial Accelerometer integrated in manufacturing environments
4.Summary
The versatility and precision of triaxial accelerometers make them essential tools across a wide range of industries, driving innovation, enhancing safety, and enabling new possibilities in fields ranging from aerospace and automotive to robotics and healthcare.

The ER-3QA-02D triaxial accelerometer stands out for its remarkable precision, comprising three A15 acceleration sensors, a 24-bit high-precision A/D converter, a 16-bit ultra-low power consumption single-chip microcomputer, and a robust mechanical structure. Noteworthy features of the ER-3QA-02D include digital output, high precision installation error, temperature compensation, and low power consumption. These attributes render it highly adaptable across a diverse spectrum of industries.

Full-system-Full-frequency-Point-High-Precision-Positioning-Module
Global Navigation Satellite System (GNSS) modules have become ubiquitous in modern technology, enabling precise positioning and navigation in various applications ranging from smartphones to autonomous vehicles. Selecting the right GNSS module is crucial for the success of your project, as different modules offer various features, performance levels, and compatibility. In this guide, we'll walk through the key considerations to help you make an informed decision.

1.Application Requirements

Begin by understanding the specific requirements of your project. Consider factors such as accuracy, update rate, power consumption, size constraints, and environmental conditions. Different applications may prioritize different aspects; for instance, a drone may require high accuracy and fast update rates, while a wearable device may prioritize low power consumption and compact size.

Fig.1 The four global GNSS systems.
Fig.1 The four global GNSS systems.

2.GNSS Constellations

GNSS systems comprise multiple constellations, such as GPS (United States), GLONASS (Russia), Galileo (European Union), BeiDou (China), and NavIC (India). Check if the GNSS module supports the constellations required for your application. Access to multiple constellations can enhance accuracy, reliability, and coverage, especially in challenging environments like urban canyons or dense foliage.

3.Accuracy and Precision

GNSS modules offer different levels of accuracy, ranging from standard positioning to high-precision solutions. Assess your project's accuracy requirements based on the intended use case. High-precision applications such as surveying or precision agriculture demand centimeter-level accuracy, whereas consumer devices like smartphones may suffice with meter-level accuracy.

RTK (Real-time kinematic) GNSS is a type of GNSS technology that uses a combination of GNSS signals and a local base station to provide highly accurate positioning data. Unlike traditional GNSS systems, which rely on data from satellites alone, RTK GNSS systems use additional data from a nearby base station to improve the accuracy of the GNSS data. This can provide positioning data that is accurate to within centimeters. It is notable that the ER-GNSS-M11 module possesses on-chip RTK positioning technology and dual-antenna directional solution.

Fig.2.

4.Integration and Compatibility

Evaluate the GNSS module's compatibility with your existing hardware, software, and communication protocols. Ensure that the module interfaces seamlessly with your microcontroller, processor, or system-on-chip (SoC). Additionally, consider factors like communication interfaces (UART, SPI, I2C), operating voltage, and available software development kits (SDKs) or libraries for easy integration.

5.Power Consumption

Power efficiency is vital, particularly for battery-powered devices or applications requiring continuous operation. Look for GNSS modules optimized for low power consumption, offering various power modes (e.g., sleep mode, power-saving modes) to minimize energy usage without compromising performance.

6.Update Rate and Fix Time

The update rate refers to how frequently the GNSS module provides position updates. Faster update rates are essential for dynamic applications such as sports tracking or autonomous vehicles. Similarly, fix time, which is the time taken by the module to acquire satellite signals and calculate a position fix, is critical for applications requiring quick startup times. For example, ER-GNSS-M11 boasts TTFF (cold start) of less than 30s.

Fig.3.

7.Environmental Considerations

Assess the GNSS module's robustness and suitability for the environmental conditions in which your device will operate. Factors such as temperature range, humidity, vibration, shock resistance, and waterproofing are essential, especially for outdoor or ruggedized applications.

8.Size and Form Factor

Consider the physical dimensions and form factor of the GNSS module, especially if space is limited in your application. Compact modules with surface-mount technology (SMT) are suitable for small devices like wearables, whereas larger modules may be preferred for applications where size is less restrictive.

Fig.4

In conclusion, selecting the right GNSS module requires careful consideration of various factors including application requirements, accuracy, constellations supported, update rate, integration compatibility, power consumption, size, environmental robustness, and cost. By evaluating these factors systematically, the ER-GNSS-M11 full system full frequency module is an excellent choice.

Small Size Quartz Accelerometer For Aerospace
1.Relationship Analysis of Accelerometer Instability and Internal Impact Factors

Quartz flexible accelerometer comprises a header and a servo circuit, functioning as a balanced and regulatory system for force feedback. Within its header are components including a pendulum, a torquer, a soft magnet, a differential capacitance sensor, and others, forming an integrated complex of various materials such as quartz, magnet, coil, epoxy glue, and electronic circuitry.

Prior to assembly, all internal components undergo stabilization treatment. Nonetheless, following the complete manufacture and assembly of the product, parameters continue to drift in storage conditions due to the effects of time and environment, primarily attributed to temperature stress and residual stress.

Fig.1 Internal structure of quartz flexible accelerometer

Fig.1 Internal structure of quartz flexible accelerometer

1.1 Temperature Stress:

Temperature stress arises from the constraint of material temperature deformation, predominantly occurring within the core, where temperature undergoes significant changes due to Joule heat generated by the torque coil during electrification, particularly prominent in wide-range accelerometers. This stress primarily stems from the disparate thermal expansion coefficients of pendulous components such as torque coil, epoxy glue, and quartz. Notably, high-polymer epoxy glue undergoes a glassy to rubber state transition at specific temperatures, leading to significant alterations in mechanical properties like elastic modulus, thereby exacerbating temperature stress during temperature fluctuations.

1.2 Residual Stress:

Residual stress refers to the internal stress that persists within bodies for self-equilibrium subsequent to the removal of external forces or application of nonuniform temperature fields. It is generated during product machining, assembly, and other processes. Changes in residual stress primarily manifest in associative components because, during component assembly, residual stresses within them undergo release or redistribution under varying boundary constraint conditions. In the case of the accelerometer, residual stress primarily accumulates in the preloading ring welded joint or the torque coil joint during epoxy glue solidification.

Fig.2 Cross-section view of quartz flexible accelerometer

Fig.2 See torque coil, Cross-section view of Q-F Accelerometer

From the overall point of view, the key parts of internal stress release are the adhesive torque coil and the preloading ring welded joints. Thus, the analysis is necessary to find out what kind of stress is conducive to the product stability.

2.Validity Analysis of Internal Stress Release by Environmental Stress

2.1 Temperature cycling

Epoxy glue can gradually release the stress in the process of temperature cycling, and with accumulation of various conditions such as temperature and its cycling number, its mechanical properties would change and tend to stable equilibrium state, i.e., physical aging. This is a relaxation process in which glassy polymers make the condensed structure transit from the nonequilibrium to equilibrium state through the micro-Brownian movement of small regional chain segments. Furthermore, physical aging bears all the following characteristics of the relaxation process:

1) being imitable—the method of heat treatment can be adopted to eliminate the history of sample storage or get the sample into the required state—and

2) being a self-deceleration process. Physical aging decreases the free volume and thereby reduces the activity of chain segments, which would lead into aging rate reduction. Then, the negative feedback self-deceleration process is formed, i.e., the closer it gets into equilibrium, the lower the rate is. Therefore, the applied temperature cycling stress can make epoxy glue release the thermal stress and get into the aging and equilibrium state.

ER-QA-03E Ultra-thin Quartz Accelerometer

Fig.3 Ultra-thin-Quartz-Accelerometer

2.2 Random vibration

Stress release by random vibration is achieved while the dynamic stress superposition results in the local plastic deformation. By applying an alternating force to metal components during vibration, if the sum of the dynamic stress amplitude and the residual stress at some points on the treated metal components reaches the yield limit, these points will produce lattice slip and microscopic plastic deformation, and this deformation starts at the maximum point of residual stress, that correspondingly makes these points release under constraints and thereby reduces the residual stress.

Random vibration works to provide mechanical energy to metal components, to improve the kinetic energy of crystal inside the workpiece, and to accelerate the speed in which lattice distortion can recover the equilibrium position. Then, under the impact of stress superposition, the crystal dislocation slip occurs inside the material, so residual stress would be released, redistributed, and rebalanced; also, the material matrix would be enhanced to resist deformation.

In essence, both temperature cycling and random vibration are ways of increasing internal energy by energy transfer. Random vibration has higher energy transfer efficiency and can greatly shorten the time of residual stress release, but vibration cannot completely eliminate residual stress. Temperature cycling is more effective for internal stress relief of the glue but is prone to bring about new distortion and secondary stress.

3.Summary

By conducting the mechanism analysis outlined above, we can ascertain that the accelerated stability test profile of the accelerometer comprises an amalgamation of temperature cycling and random vibration. Within this profile, the boundary conditions pertaining to factors such as temperature, temperature variation rate, and vibration levels can be deduced through enhancement experiments.

It's worth noting that the zero bias repeatability of the quartz flexure accelerometer ER-QA-01A is 10μg, and the scale factor repeatability is 10ppm. It is applied in aircraft carrier microgravity measurement systems, inertial navigation systems, and static angle measurement systems.
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More Technical Questions
1. Optimizing Compensation Loop for Quartz Accelerometer

1. 2 Ways to Improve Shock Resistance Performance of Q-Flex Accelerometer

2. Parameters to Evaluate Performance of Quartz Flexure Accelerometers

3. Factors Affecting the Stability of Q-Flex Accelerometers

4. Structure Design of High Precision Quartz Flexible Accelerometer

5. Methods to Maintain the Long-Term Performance of Quartz Flexure Accelerometers

Understanding RTK GPS: Precision Positioning Technology - [ericcointernational.com]

In today's digitally driven world, accurate positioning is fundamental to various applications, from navigation and surveying to precision agriculture and autonomous vehicles. Real-Time Kinematic (RTK) GPS is a revolutionary technology that has transformed the accuracy and reliability of GPS positioning. In this article, we delve into the intricacies of RTK GPS, exploring how it works, its advantages, applications, and its role in shaping diverse industries.

1.What is RTK GPS?

RTK GPS stands for Real-Time Kinematic Global Positioning System. It is a satellite-based navigation system that provides highly accurate positioning information in real-time. Unlike conventional GPS systems, which typically offer accuracy within several meters, RTK GPS can achieve centimeter-level accuracy, making it invaluable for applications that require precise positioning data.

2.How does RTK GPS work?

At the core of RTK GPS technology is a process called kinematic positioning. RTK GPS systems consist of two main components: a base station and a rover receiver. The base station, typically placed at a known location with a precisely determined position, receives signals from GPS satellites and calculates corrections for errors in the positioning data. These corrections are then transmitted to the rover receiver, which is mounted on a moving object or device. The rover receiver uses the corrections received from the base station to refine its own GPS measurements in real-time, resulting in highly accurate positioning information.

Fig.1 Principle of RTK GPS
Fig.1 Principle of RTK GPS
3.Advantages of RTK GPS:

One of the most important features of RTK GPS is its ability to provide highly accurate positioning data. This is achieved by using a local base station in addition to satellite signals, which allows the system to correct for any errors that may be present in the GPS data. This can provide positioning data that is accurate to within centimeters, making it ideal for a wide range of applications.

Another key feature of RTK GPS is its ability to provide real-time data. Because the system uses a local base station in addition to satellite signals, it can provide real-time data that is accurate to within milliseconds. This makes it ideal for applications that require real-time navigation, such as autonomous vehicles and drones.

Fig2. Schematic diagram of a mobile measurement system using GPS RTK.
Fig2. Schematic diagram of a mobile measurement system using GPS RTK.
In addition to its high accuracy and real-time capabilities, RTK GPS also offers a number of other features that make it ideal for a wide range of applications. These include:

Long battery life: Because the system uses a local base station in addition to satellite signals, it can operate for longer periods of time without needing to be recharged.

Robustness: RTK GPS systems are designed to be robust and reliable, even in difficult environments. This makes them ideal for use in rugged terrain and other challenging conditions.

Low cost: Compared to other types of high-accuracy GPS systems, RTK GPS is relatively inexpensive. This makes it accessible to a wide range of users, from individual surveyors to large construction companies.

4.Applications of RTK GPS:

RTK GPS technology is utilized in numerous sensor applications, notably positioning modules, and extends its benefits across diverse industries and sectors, including:

Precision Agriculture: RTK GPS enables farmers to precisely navigate their equipment, apply fertilizers and pesticides with accuracy, and create detailed field maps for yield optimization.

Fig.3 Precision agriculture
Fig.3 Precision agriculture
Construction and Surveying: In construction and surveying projects, RTK GPS facilitates precise measurement, layout, and machine control, leading to improved efficiency and reduced costs.

Autonomous Vehicles: RTK GPS plays a crucial role in the development and operation of autonomous vehicles by providing accurate positioning data for navigation and control.

Infrastructure Monitoring: RTK GPS is used for monitoring and managing critical infrastructure such as bridges, dams, and pipelines, helping detect movements and deformations with high precision.

Fig.4 RTK GPS in bridge monitoring
Fig.4 RTK GPS in bridge monitoring
5.Summary

RTK GPS technology represents a significant advancement in the field of positioning and navigation. With its ability to provide centimeter-level accuracy in real-time, RTK GPS has become indispensable in numerous industries, driving innovation and efficiency. As technology continues to evolve, the applications and benefits of RTK GPS are expected to expand further, paving the way for new possibilities in precision positioning and beyond.

Moreover, the ER-GNSS-M02 positioning module provides robust support for multi-frequency positioning across all major satellite constellations, including Beidou, GPS, GLONASS, Galileo, QZSS, and NavIC. With its high-precision RTK algorithm engine, achieving centimeter-level positioning accuracy becomes effortless.

Additionally, the module comes equipped with an integrated Inertial Measurement Unit (IMU) and employs a tight combination algorithm, ensuring seamless and continuous navigation and positioning output. Its compact size, minimal power consumption, and ease of system integration make it an ideal choice for various applications. Furthermore, the module supports long baseline RTK solutions and boasts fast initialization times, enhancing its versatility and usability.

Analysis of Processing and Assembly Techniques for Q-Flex Accelerometer

The precision of Q-Flex accelerometer is closely related to the processing and assembly accuracy during production. Accelerometers are instruments with complex production processes, and a significant number of uncertain factors are introduced during processing and assembly. A specific analysis of these factors helps improve the accuracy of accelerometers.

1.Processing Techniques

Compared to other precision instruments, the components of Q-Flex accelerometers have thin walls, high precision, complex shape features, and small dimensions. During the processing and assembly process, their manufacturing accuracy, shape errors, and dimensional precision are all at the micron level. They also involve the conversion of multiple physical parameters during operation and exhibit the characteristics of coupling effects between multiple physical fields.

During these conversions and coupling effects, components with corresponding physical properties are undoubtedly required. However, these components introduce some uncertain factors during assembly, inevitably leading to minor errors in the entire process. Since accelerometers themselves have a compact structure, these minor errors will inevitably affect the performance of the accelerometer.

Fig.1 Quartz pendulous reed
Fig.1 Quartz pendulous reed
Quartz wafers and permanent magnets are core precision components of Q-Flex accelerometers, and their processing accuracy and performance directly affect the performance of the entire system. Quartz crystal is the main component of quartz wafers, which is a brittle non-metallic material with characteristics of high strength, high hardness, low conductivity, and low fracture toughness. Unlike common metal materials, the processing method greatly affects its strength, and any improper processing technique will affect the reliability, fracture strength, and surface integrity of quartz.

Currently, the commonly used processing methods are laser cutting combined with chemical etching. This method utilizes chemical etching technology to corrode beams and C-shaped grooves without residual stress. Laser trimming is then used for smooth cutting with high speed. However, this method involves multiple procedures such as sealing, masking, and clamping, making it a complex process. Experienced workers are required to accurately control the etching time and acid temperature, and it is prone to produce defective products.

Fig.2 Precise preparation of quartz pendulous reed by using picosecond laser modification assisted wet etching
Fig.2 Precise preparation of quartz pendulous reed by using picosecond laser modification assisted wet etching
Compared to the very thin quartz beams, this method tends to result in higher surface roughness and uneven bending stress. Therefore, researching new processing techniques is necessary to improve processing accuracy and efficiency.

2.Assembly Process Techniques

Q-Flex accelerometers are highly precise instruments, and the quality of their assembly process directly determines the performance of the accelerometer. Currently, traditional manual assembly methods are still used for accelerometer assembly, with little innovation in assembly process techniques despite minor adjustments over the years. Designers and process engineers lack a systematic understanding of the impact of assembly process techniques on performance, leading to a lack of scientificity in establishing assembly processes.

The current assembly process for producing accelerometers follows a process of assembly first, then testing. However, due to the complexity of the assembly process, it is difficult to accurately identify factors leading to performance degradation. Moreover, the performance is closely related to the operation habits, skills, experience, and proficiency of assembly workers, resulting in the performance of produced accelerometers being approximately normally distributed, with a low rate of superior products. Even the use of high-precision components does not necessarily guarantee the assembly of accelerometers with superior performance.

Fig.3 A Triaxial Quartz Accelerometer
Furthermore, to design Q-Flex accelerometers with high precision over a small range, and to improve the overall performance of accelerometers, it is necessary to consider the extent to which processing and assembly techniques affect their performance. Scientifically improving the processing techniques and assembly processes of accelerometers is essential to reduce manufacturing complexity.

3.Summary

The precision of quartz flexure accelerometers relies on meticulous processing and assembly techniques. Accelerometers undergo complex manufacturing processes, where uncertainties affect precision. Systematic improvements in precision machining of core components are crucial. Additionally, the assembly process significantly impacts performance, requiring scientific advancements to reduce manufacturing complexity and enhance overall performance consistency.

It's worth noting that the zero bias repeatability of the quartz flexure accelerometer ER-QA-01A is 10μg, and the scale factor repeatability is 10ppm. It is applied in aircraft carrier microgravity measurement systems, inertial navigation systems, and static angle measurement systems.

https://www.ericcointernational.com/application/optimizing-compensation-loop-for-quartz-accelerometer.html

The quartz flexure accelerometer mainly consists of torque generator, pendulum assembly, differential capacitance sensor, and rebalancing loop, widely used in the aerospace field as a critical component of inertial navigation systems. Among these, the torque generator is a device that generates a feedback torque to balance the inertial torque when there is acceleration acting on the input shaft, consisting of magnetic yoke, magnetic steel, magnetic cap, compensation ring, and coil assembly.

Fig.1 Internal structure of quartz flexible accelerometer
Fig.1 Internal structure of quartz flexible accelerometer
1.Introduction

The scale factor K1 is the feedback current required when the accelerometer input unit acceleration is proportional to the pendulum effect and inversely proportional to the torque generator coefficient, i.e.,

Formula. 1
Formula. 1
Kb is the pendulum effect; Kt is the torque generator coefficient; m is the mass of the pendulum assembly; L is the length from the pivot to the center of mass of the pendulum assembly; r is the coil radius; n is the number of turns of the coil; R is the distance from the coil center to the flexure point of the pendulum piece; B is the working air gap magnetic flux density. The torque generator coefficient and pendulum effect together determine the magnitude of the accelerometer scale factor, ultimately affecting the accuracy of the entire system.

Temperature is one of the important factors affecting the torque generator coefficient. Firstly, temperature changes cause deformation of the torque generator, leading to thermal error due to thermal expansion and contraction effects; secondly, temperature alters the magnetic properties of various components, thereby affecting the magnitude and stability of the working air gap magnetic flux density.

In general, the measurement accuracy of high-precision quartz flexure accelerometers is better than 10^-4, and the scale factor requirement is 1.1mA/g~1.5mA/g, with a temperature coefficient of the scale factor less than 60×10^-6/℃. The magnetic flux density B is the parameter in equation (1) that has the greatest impact on the scale factor. Even if the change is small, it will have a significant impact on the entire system and should be analyzed in detail.

2.Methods

The schematic diagram of the torque generator of the quartz flexure accelerometer is shown in Figure 2.

Fig.2 Diagram of the torquer
Fig.2 Diagram of the torquer
The upper part of Figure 2 shows a schematic diagram of a single torque generator, and the lower part shows a schematic diagram of the upper and lower magnetic circuits. Among them, the magnetic steel, magnetic cap, and compensation ring form a magnetic steel assembly through interference fit, fixed in the upper and lower magnetic yokes, forming opposing axial magnetized magnetic circuits, with each other as the opposite magnetic poles, and most of the magnetic lines are squeezed into the air gap, basically eliminating axial magnetic leakage.

In addition, the two torque coils are also connected in push-pull mode, which can not only eliminate the nonlinearity error caused by the demagnetization effect formed by the torque current but also compensate for errors caused by uneven material properties and processing asymmetry. The quartz flexure accelerometer has high upper and lower symmetry in structure, and each magnetic circuit is independent of each other, allowing for experimental research on one of the torque generators.

The working air gap is the region where the torque coils are located, and the stability of its magnetic field directly affects the stability of the scale factor. It can be seen from Figure 2 that the range of the air gap occupied by the torque coils is very small. Even at the maximum swing amplitude of the pendulum piece, it only fluctuates up and down by ±0.02mm, so only the change in the magnetic field at the working air gap needs to be analyzed with temperature.

The calculation of the magnetic circuit of the permanent magnet is an important part of designing the torque generator. The working point of the magnet should be selected above the maximum energy product point. When the temperature rises, the values of the residual magnetization intensity Br and coercive force Hc of the permanent magnet decrease, resulting in a change in the magnetic flux density in the area where the coil is located. At present, there are mainly two solutions:

Seek new types of magnetic steel materials. The second-generation rare earth permanent magnet material Sm2Co17 has been widely used in high-precision accelerometers, and its lower residual magnetization temperature coefficient and coercive force temperature coefficient have reduced the magnetic field temperature drift to a certain extent.

Optimize the structural dimensions of the torque generator. Wang C et al. found that when the cylindrical magnetic pole pieces are changed to cap-shaped magnetic caps, the magnetic field in the air gap becomes more uniform, and the dimensions are optimized, improving the linearity of the accelerometer. To improve the temperature stability of the working air gap magnetic flux density, it is mainly achieved by paralleling compensation rings on the magnetic steel.

The material of the compensation ring is a magnetic temperature compensation alloy, and its relative magnetic permeability increases with decreasing environmental temperature. The calculation formula for the temperature coefficient δu of the magnetic permeability is:

Formula. 2
ur1 is the relative magnetic permeability of the compensation ring at temperature T1, ur2 is the relative magnetic permeability of the compensation ring at temperature T2, neglecting the influence of the magnetic cap and magnetic yoke, it can be seen that the magnetic flux of the permanent magnet is equal to the sum of the air gap and the magnetic flux of the magnetic temperature compensation alloy, i.e.,

Formula. 3-5
Formula. 3-5
If the cross-sectional area and vertical magnetic flux density passing through the compensation ring can be adjusted correctly so that ∂·Bmag·Smag/ΔT=∂·Bcom·Scom/ΔT, ∂Bgap·Sgap·ΔT=0, thus ensuring the temperature stability of the air gap magnetic flux density. Finite element simulation by ANSYS shows that the magnetic field formed around the magnetic steel assembly in its surrounding air gap is not a uniform magnetic field, and the compensation ring is in contact with the bottom of the magnetic yoke, so the vertical magnetic flux density passing through the compensation ring is related to its height, height and cross-sectional area are the key factors affecting the temperature stability of the working air gap magnetic flux density.

3.Conclusion

In summary, this paper proposes methods to improve the stability and measurement accuracy of quartz flexure accelerometers: using advanced materials and optimizing the dimensions of compensation rings. It is worth noting that the performance of the quartz flexure accelerometer ER-QA-03C1 is very high, with a scale factor temperature coefficient of ≤±15 ppm/℃, zero offset repeatability of ≤15μg, and scale factor repeatability of ≤15 ppm. In addition to aerospace applications, it can also be used for static and dynamic acceleration measurements.

Fig.1 High Performance Quartz Accelerometer
The stability of scale factor and zero bias of Q-Flex accelerometers is crucial in assessing the performance of accelerometers. During the measurement of minute motion acceleration, certain physical factors such as external magnetic interference and fluctuating temperature fields can affect the stability of scale factor and zero bias of accelerometers.

This article addresses the issue of magnetic field and temperature variations affecting the stability of scale factor and zero bias of quartz flexible accelerometers, discussing the adoption of rigorous electromagnetic shielding structures and temperature control structures to enhance the measurement accuracy of acceleration devices.

1.Working Principle of Accelerometer

The acceleration measurement device adopts the principle of quartz flexible accelerometer measurement, using four quartz flexible accelerometers as sensors in a redundant design of four axes. Among them, two accelerometers measure vertical acceleration along the Z-axis and -Z-axis (improving measurement accuracy through data fusion), while the other two measure horizontal acceleration along the X-axis and Y-axis.

By improving the internal structure of the accelerometer device, rigorous electromagnetic shielding and precise temperature control are employed to enhance measurement accuracy and achieve high-precision three-dimensional motion acceleration measurement of the carrier.

Fig. 1 Operating principle chart of quartz-flex accelerometer
2.Structural Design of Quartz flexible Accelerometer Measurement Device

The accelerometer measurement device adopts a frame assembly structure with heat sinks installed around the shell, a base installed at the bottom, connected to the mounting platform, and electrical connectors set at the top for information communication.

The accelerometer measurement device mainly consists of a frame, quartz flexible accelerometers, shielding structures for accelerometers and measurement channels, temperature control structures for accelerometers and measurement channels, and accelerometer mounting structures. The accelerometer mounting structure is composed of a rectangular block of aviation aluminum with four cylinders carved out. This mounting structure ensures the fixed positions of each accelerometer and reduces the overall device volume. The structure of the accelerometer measurement device is shown in Fig. 2.

Fig. 2 The decomposition texture view of quartz-flex accelerometer
Fig. 2 The decomposition texture view of quartz-flex accelerometer
2.1 Shielding Structure Design

2.1.1 Accelerometer Shielding Structure Design

External magnetic fields can cause lag and non-linear effects on the scale factor of quartz flexible accelerometers. Experimental data suggests that a magnetic field variation of 10Gs can cause a scale factor change of 5~20ppm.

Considering the inevitable openings and seams in the accelerometer measurement device, which may cause magnetic leakage, the magnitude of magnetic leakage mainly depends on the maximum linear dimension of the openings. Therefore, the shielding structure of the accelerometer measurement device adopts as many small-area openings as possible to replace large-area openings to enhance the shielding effect. Furthermore, the shielding material selected is the Permalloy alloy 1J85, which has a high permeability and effectively suppresses low-frequency magnetic field interference.

Considering the reflection, absorption, and other factors of the shielding structure, the overall shielding effect can be represented as follows:

Where A is the absorption loss, R is the reflection loss, Bs is the correction term caused by multiple reflections inside the shielding layer, x is the thickness of the shielding layer, μr is the relative permeability, σr is the relative conductivity, f is the frequency of the interfering magnetic field, and δ is the skin depth.

From the above, it can be seen that for low-frequency magnetic field interference, the shielding effect of Permalloy alloy is excellent. However, this material has a low magnetic saturation intensity, and it is easy for Permalloy alloy to reach magnetic saturation when encountering higher magnetic field intensity. Therefore, the accelerometer measurement device adopts a dual-layer shielding structure to reduce magnetic leakage.

The first layer of shielding uses aviation aluminum, which has a high magnetic saturation intensity and low permeability; the second layer of shielding uses Permalloy alloy, which has a high permeability. After passing through the first layer of shielding, the external interfering magnetic field is significantly attenuated, and then, using the high permeability of the second layer of shielding, the interfering magnetic field can be further reduced to a very low level. The decomposition view of the accelerometer shielding structure is shown in Fig. 4.

Fig. 4 The shield structure view of quartz-flex accelerometer
Fig. 4 The shield structure view of quartz-flex accelerometer
2.1.2 Measurement Channel Shielding Structure Design

The shielding structure of the measurement channel consists of an upper cover and a lower cover assembled into a shielding shell, made of Permalloy alloy 1J85. Each channel is wrapped in a shielding shell to achieve electromagnetic shielding of the measurement channel. The shielding structure of the measurement channel is shown in Fig. 5.

Fig. 5 Measurement channel shielding structure
Fig. 5 Measurement channel shielding structure
2.2 Temperature Control Structure Design

2.2.1 Accelerometer Temperature Control Structure Design

Temperature changes can affect the zero bias and scale factor of quartz flexible accelerometers. There are two main factors causing temperature changes in accelerometers: first, after the device starts, the internal temperature of the device will gradually rise, causing the temperature of the accelerometer to change; second, the torque coil inside the device will heat up when powered, causing the temperature of the accelerometer to change.

The working environment temperature of the accelerometer measurement device varies greatly, while the accelerometer needs to meet the working environment requirement of 0°C to 50°C, making precise temperature control very challenging. Conventional single-stage temperature control schemes are difficult to meet the temperature control requirements.

To achieve an accuracy of ±0.1°C in accelerometer temperature control, the accelerometer measurement device adopts a two-stage precise temperature control structure. The two-stage temperature control structure is shown in the decomposition in Fig. 6. The temperature stability accuracy of the first-stage temperature control structure is designed to be ±0.5°C, with a temperature control target of 30°C.

Fig. 6 The temperature control structure view of quartz-flex accelerometer
Fig. 6 The temperature control structure view of quartz-flex accelerometer
A digital temperature sensor DS18B20 is used as the temperature measurement sensor, and a thermoelectric cooler (TEC) is used as the temperature control component. Changing the direction and magnitude of the control current can achieve different heating or cooling powers using the thermoelectric cooler.

The temperature accuracy of the second-stage temperature control structure is designed to be ±0.1°C, matching the target accuracy of the accelerometer, with a temperature control target of 45°C, maintaining a certain temperature difference with the first-stage temperature control environment. The second-stage temperature control structure uses platinum resistance as the temperature measurement sensor, with stable temperature coefficients. Thin film heaters are used as the temperature control components, wrapped around the first layer of shielding of the accelerometer, achieving different heating powers by changing the control current.

To improve temperature control stability, the accelerometer is insulated with polyurethane as the insulation material, which has low thermal conductivity and good processing performance, effectively achieving thermal insulation.

2.2.2 Measurement Channel Temperature Control Structure Design

The temperature control structure of the measurement channel is similar to the first-stage temperature control structure of the accelerometer, using a thermoelectric cooler (TEC) for cooling or heating. One side of the TEC is closely attached to the upper and lower covers of the shielding shell of the measurement channel, and the other side is closely attached to the heat sink housing. The shielding shell is wrapped with insulation, made of polyurethane. The temperature control structure of the measurement channel is shown in Fig. 7.

Fig. 7 The heat-simulation result of quartz-flex accelerometer
Fig. 7 The heat-simulation result of quartz-flex accelerometer
Conclusion

This paper proposes an accuracy improvement scheme for the influence of external magnetic fields and temperature variations on the measurement accuracy of quartz flexible accelerometers. By optimizing the structure and designing accelerometer magnetic shielding structures and precise two-stage temperature control structures, the stability of scale factor and zero bias is enhanced, thereby improving measurement accuracy.

It is worth noting that the high-performance quartz flexible accelerometer ER-QA-03A has an effective vibration acceleration of 6 grms, using high-quality quartz crystals, capable of adapting to high-temperature, high-pressure, high-vibration environments, and various environmental conditions with high acceleration applications, exhibiting extremely high reliability and stability.

In addition, the ER-QA-03A1 series of accelerometers have a scale factor of 15 ppm and bias repeatability of 10 μg, achieving high-precision measurements. Apart from extensive applications in aerospace and military fields, it is also widely used in automotive, medical, and research fields. In scientific research, it can be used for studying earthquakes, crustal movements, cosmology, and microgravity environments.

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A time service is a system or institution that provides accurate and synchronized timekeeping for a wide range of applications. From coordinating global financial transactions to ensuring the precision of scientific experiments, satellite timing are the backbone of countless industries and activities that rely on precise timing. This article mainly introduces satellite timing and its several application fields.

1.The History of Timing

The history of satellite timing is closely intertwined with the development of satellite technology and the quest for accurate timekeeping on a global scale. The journey began with the launch of the first artificial satellite, Sputnik 1, by the Soviet Union on October 4, 1957. While Sputnik 1 itself did not carry precise timing equipment, its launch marked the beginning of the space age and paved the way for subsequent advancements in satellite-based timekeeping.

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In the early years of space exploration, satellites primarily served scientific and military purposes. However, the need for precise timing capabilities became apparent as researchers and engineers sought to synchronize experiments, coordinate spacecraft operations, and facilitate communication across vast distances.

The concept of Global Navigation Satellite Systems (GNSS) emerged in the late 20th century, aiming to provide precise positioning, navigation, and timing services to civilian and commercial users worldwide. The Global Positioning System (GPS), developed by the United States Department of Defense, became the first fully operational GNSS, achieving initial operational capability in the 1980s. GPS utilized a constellation of satellites broadcasting precise timing signals synchronized with Coordinated Universal Time (UTC), enabling users to determine their precise position and time anywhere on Earth.

2.Satellite Timing and Other Methods of Timing

2.1 Shortwave timing

Timing is carried out using shortwave radio with wavelengths between 100m and 10m (frequencies: 3MHz to 30MHz).

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Take China as an example. In Lintong, Shaanxi, there is the headquarters of the National Time Service Center of the Chinese Academy of Sciences. It is responsible for the generation, maintenance, and dissemination of China Standard Time (Beijing Time).

The time signal transmitter of the National Time Service Center is located in Pucheng, Shaanxi. Shortwave radio stations here use frequencies of 2.5MHz, 5MHz, 10MHz, and 15MHz to continuously broadcast China's shortwave radio time signal, with the call sign BPM.

Shortwave time signals are transmitted via sky wave and ground wave. Ground waves can transmit up to 100 kilometers, while sky waves cover a radius of over 3000 kilometers, basically covering the entire territory of China, with timing accuracy at the millisecond level.

2.2 Longwave timing

Timing is carried out using longwave radio with wavelengths between 10km and 1km (frequencies: 30kHz to 300kHz).

The longwave radio station of the National Time Service Center of China has the call sign BPL, with a transmission frequency of 100kHz.

The ground wave range of longwave time signals is 1000-2000 kilometers, and the sky wave range is 3000 kilometers, basically covering inland areas and nearby sea areas of China, with timing accuracy at the microsecond level.

In addition, there are other methods of timing

Low frequency time code timing
Telephone timing
TV timing
Network timing
2.3 Satellite timing

People use navigation and positioning apps like Google Maps and Baidu Maps every day. We should also know that these apps are able to provide navigation and positioning because phones can communicate with satellites and use the services provided by satellites.

Navigation satellite systems that provide navigation and positioning services are called GNSS (Global Navigation Satellite Systems).

The GPS we are familiar with is the GNSS system of the United States and also the earliest GNSS system globally. The now-famous BeiDou is China's independently developed and constructed GNSS system. Other GNSS systems with global coverage capabilities include Russia's GLONASS and Europe's Galileo.

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Many people do not know that in addition to positioning and navigation, GNSS systems also have a very important function, which is—timing. The three core capabilities of GNSS, commonly referred to as PVT (Position, Velocity, and Timing) .

Then, how does GNSS achieve time synchronization?

Each GNSS satellite is equipped with an atomic clock. This means that the satellite signals sent contain accurate time data. By decoding these signals using specialized receivers or GNSS timing modules, devices can be quickly synchronized with atomic clocks.

Compared to the previously mentioned longwave, and shortwave, GNSS satellite timing has significant technical advantages.

GNSS timing has higher accuracy. Take BeiDou as an example. The time of the BeiDou Satellite Navigation System is called BDT. BDT belongs to atomic time and can be traced back to Coordinated Universal Time (UTC) of China's National Time Service Center, with a time difference control accuracy to UTC of less than 100 nanoseconds. For example, high precision positioning module ER-GNSS-M01 possesses timing accuracy of 10 ns.

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Apart from accuracy, GNSS satellite timing also has inherent coverage advantages. Longwave and shortwave ground-based timing are limited by physical propagation distances. If there are obstacles like high mountains, the propagation distance will be further reduced. However, GNSS satellite timing has a much stronger coverage capability. Especially for scenarios like ocean navigation and aerospace.

3.Application of Satellite Timing Services

3.1 The Impact of GNSS Satellite Timing in the Aviation Field

In the aviation domain, GNSS satellite timing is crucial for ensuring flight safety. Pilots can utilize GNSS satellite timing to understand the aircraft's position and velocity, thereby enabling more accurate route planning and flight control. Additionally, GNSS satellite timing can be used for analyzing the causes of flight delays, assisting airlines in improving service quality.

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3.2 Applications of Satellite Timing in the Communication Field

In the communication sector, GNSS satellite timing is primarily applied in the construction and management of mobile communication networks. By achieving precise time synchronization among base stations, the quality and stability of wireless communication can be enhanced. Since alternating current (AC) is commonly used in daily life, the direction of current in AC changes over time. When different power grid devices are interconnected, inconsistencies in time can lead to discrepancies in peak and valley periods, resulting in unnecessary energy loss or even equipment damage and network paralysis, causing widespread power outages.

Furthermore, GNSS satellite timing can be utilized for troubleshooting and maintenance of network faults, thereby improving the service level of telecommunication operators.

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3.3 The Value of GNSS Satellite Timing in the Scientific Research Field

In scientific research, GNSS satellite timing holds significant value. For example, in astronomical observations, precise measurement of celestial bodies' motion trajectories can be achieved through GNSS satellite timing. In geological exploration, GNSS satellite timing aids scientists in studying the structure and evolution processes of the Earth's interior. In biomedical research, GNSS satellite timing can be applied in areas such as drug development and disease diagnosis.

4.Summary

With the continuous advancement of the digital wave, high-precision timing services will enter more industries and give rise to more application scenarios. The importance of timing-related equipment and systems is becoming increasingly prominent, gradually evolving into vital national information infrastructure.

Of note, GNSS timing can cover the entire globe, providing highly accurate and reliable timing signals whether on land, at sea, or in the air. This global coverage makes satellite timing systems an ideal choice for many application fields, and it's also an important area of competition among many superpowers.

I will appreciate it if you find this article helps you a lot. Read the following articles to get more information about GNSS.

Read the full article:
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In the field of inertial navigation and inertial guidance systems, accelerometers are one of the core sensing components. They are primarily used to measure the linear acceleration acting on their sensitive axis, providing the instrument with motion velocity and displacement coordinates.

Therefore, the technological level of accelerometers directly determines the technological level of the control system. Among accelerometers, quartz flexible accelerometers have the characteristics of small size, high precision, and high reliability, making them the most mature accelerometers currently available.

This article starts from the structural mechanism of sensors, based on theoretical mathematical models, and proposes relevant improvements in materials enhancement, high-precision machining technology, high-accuracy testing environment.

1. Mechanism of Quartz Flexure Accelerometers

1.1 Basic Structure of Accelerometers

The main structure of quartz flexible pendulum accelerometers is shown in Figure 1. The accelerometer consists of upper torque components, pendulum components, lower torque components, compensating rings, housing, and servo circuits. The upper and lower torque components are composed of magnetic steel, magnetic pole pieces, and compensating rings, while the pendulum component consists of pendulum pieces and upper and lower movable coils.

Fig.1 Internal structure of quartz flexible accelerometer
Fig.1 Internal structure of quartz flexible accelerometer
1.2 Working Principle of Accelerometers

The pendulum tongue of the pendulum piece and a pair of torque coil bonded to it constitute the detection mass pendulum of the accelerometer. When there is acceleration input along the accelerometer’s input axis, the detection mass pendulum will undergo a deflection motion away from the equilibrium position due to inertial effects around the flexible pivot. The differential capacitance sensor on the accelerometer outputs a differential capacitance, which the differential capacitance detector converts into a certain amount of current value. This current is then processed through an integral amplification circuit to form a balanced torque current.

The torque coil is in a stable magnetic field generated by magnetic steel. When a balanced torque current passes through the coil, electromagnetic force acts on the detection mass pendulum to form a balanced torque. The magnitude of the balanced torque is equal and opposite to the inertial torque, allowing the detection mass pendulum to achieve dynamic balance under the action of the balanced torque, completing the detection loop. Refer to Figure 2 for a schematic diagram of the working principle.

Fig.2 Accelerometer schematic diagram
2. Several Paths to Maintain Long-Term Performance of Quartz Flexure Accelerometers

2.1 Mathematical Models

Starting from the structure of quartz flexure accelerometers, based on the theoretical mathematical models of sensors, and utilizing techniques such as mathematical modeling, numerical analysis, model verification, and data mining, improvements are proposed from various aspects such as material enhancement, high-precision machining technology, and high-accuracy testing environment.

This fundamentally addresses the issue of active optimization, guiding production with mathematical models, and predicting the static and dynamic performance of products based on various structural parameters.

2.1.1 Static Mathematical Model

Quartz flexible accelerometers generate error torques around their output axes, resulting in nonlinearity and cross-coupling effects in the performance of accelerometers. To analyze the specific factors affecting accelerometer performance, the following error model is established:

error model
From the formula, it can be inferred that the main causes affecting accelerometer measurement error are: the nonlinear error and stability error of scale factor K1; cross-coupling error caused by offset angle during pendulum component movement; offset error caused by interference torque Md, elastic restoring torque Kh β, and other reasons.

2.1.2 Dynamic Mathematical Model

Refer to Figure 3 for a schematic diagram of the accelerometer pendulum assembly. To analyze the motion characteristics of accelerometers, the movement of the pendulum component under acceleration can be simplified into a bending beam model, based on which a linear kinematic model of the accelerometer can be established:

Fig.3 Quartz pendulum assembly

2.2 Low Coefficient of Thermal Expansion, High Stability Material Technology

2.2.1 Low Hydroxyl, Ultra-Pure Quartz Glass

Air bubbles, impurities, and hydroxyl groups in quartz glass can affect its mechanical properties such as strength, hardness, and elastic modulus, thereby reducing the performance of pendulum pieces and affecting the accuracy of quartz accelerometers. It is necessary to use high-performance materials with metal impurity content less than 1 ppm, hydroxyl group content less than 5 ppm, and optical non-uniformity within a φ100m diameter less than 2 ppm.

Due to the extremely low metal impurity and hydroxyl group content in such high-performance materials, and the most complete silicon-oxygen network structure in the glass structure, they possess characteristics such as high stability, high hardness, and high elastic modulus. Therefore, they are the preferred core components for high-precision strategic quartz flexible accelerometers.

2.2.2 Ultra-Low Coefficient of Thermal Expansion Alloy

The main cause of structural dimension instability is the change in component dimensions due to environmental temperature variations. The smaller the coefficient of thermal expansion of the component material, the smaller the dimensional changes caused by environmental temperature changes, resulting in better overall structural dimensional stability.

Fig.4 4J36 invar alloy
Fig.4 4J36 invar alloy
Upper and lower yokes and loops typically employ the low expansion alloy 4J36 (Fe-Ni36). By further adjusting and modifying the chemical composition of the material and applying ultra-pure melting, a class of alloy similar to 4J36 with an extremely low coefficient of thermal expansion is obtained. This lowers the average thermal expansion coefficient of the alloy in the full temperature range (-40°C to 70°C) to 0.55 ppm, significantly enhancing its compatibility with quartz glass materials.

2.2.3 Dual Low-Temperature Coefficient High-Stability Permanent Magnet Alloy

Permanent magnets provide the energy for the working air gap magnetic field, and the rational selection of permanent magnet materials is a key part of magnetic circuit design. The stability of accelerometer scale factor and temperature coefficient depends largely on the stability and temperature coefficient of the permanent magnet material’s magnetic properties. The basic principle for selecting permanent magnet materials is to choose materials with high magnetic energy product, high residual magnetism, high coercivity, and low temperature coefficient.

New types of permanent magnet materials with low residual magnetism temperature coefficients and low coercivity temperature coefficients, while ensuring the residual magnetism temperature coefficient, also have coercivity temperature coefficients lower by an order of magnitude than traditional magnetic materials. This effectively reduces the magnetic field drift caused by fluctuations in coercivity, resulting in better temperature stability and time stability of the magnetic field, potentially ensuring long-term stable use of quartz accelerometers in variable temperature environments.

Fig.5 Magnetic attenuation diagram of traditional magnets with coefficient α and a new type of magnet with coefficient α and β
Fig.5 Magnetic attenuation diagram of traditional magnets with coefficient α and a new type of magnet with coefficient α and β
Note: α is low remanent temperature coefficient and β means low coercivity temperature coefficient

2.3 Low Stress Control Technology and High-Precision Machining and Assembly Technology

Since quartz flexure accelerometers are ultra-high-precision instruments, the machining level of components has a huge impact on product quality, and the level of geometric tolerance technology determines the performance of the product. In order to maintain the long-term stability and performance retention period of accelerometers, it is essential to focus on low-stress machining of components and low-stress assembly to achieve stress control and elimination accurately.

1. Nano-g Level High-Stability Accelerometer Evaluation System and Application Technology

According to the testing requirements of high-precision instruments, the stability of acceleration provided by the testing environment must far exceed the accuracy of the accelerometer itself. Developing a high-stability testing environment to meet the requirements of high-precision instrument testing is crucial. The adjustment and calibration of high-precision accelerometers must be based on a higher-precision testing environment, testing equipment, and more comprehensive test methods.

1. Conclusion

This article proposes measures to maintain the long-term stability of accelerometers based on the structural mechanism of sensors, theoretical mathematical models, and improvements in materials, high-precision machining technology, and high-accuracy testing environments.

It is worth noting that the ER-QA-03C quartz accelerometer exhibits outstanding performance, with a scale factor of 1.0 ± 0.2 mA/g. The zero offset repeatability of the 03C1 series is ≤15 μg, and the scale factor repeatability is ≤15 ppm. It has extremely wide applications in fields such as aerospace, aviation, navigation at sea and on land.

Анализ температурных характеристик кварцевого гибкого акселерометра

Кварцевый гибкий акселерометр относится к акселерометру с маятниковой структурой баланса сил, и его показатели производительности могут соответствовать требованиям большинства рабочих сред. Поэтому он имеет широкий спектр применения в таких областях, как аэрокосмическая, оборонная и военная промышленность.

Однако, поскольку он является одним из основных компонентов инерциальной навигационной системы (гироскоп и акселерометр), его характеристики (особенно точность работы) часто напрямую влияют на то, сможет ли вся система работать нормально. Следовательно, изучение методов повышения точности измерений акселерометров стало важнейшим аспектом исследований в области инерциальных технологий.

Рис.1 Механическая структурная схема кварцевого гибкого акселерометра
Рис.1 Механическая структурная схема кварцевого гибкого акселерометра
Точность измерений акселерометров связана не только с их собственными конструктивными схемами, техническими процессами и материалами изготовления, но и с рабочей средой, в которой они находятся, особенно с рабочей температурой.

Изменение температуры рабочей среды может вызвать тепловое расширение и сжатие компонентов, а также изменение физических параметров материалов, что в первую очередь отражается на их масштабном коэффициенте и нулевом смещении. Это стало важным аспектом, ограничивающим производительность акселерометров в текущем процессе разработки.

Поэтому необходимо качественно проанализировать влияние температуры рабочей среды на работу акселерометров, а затем изучить методы повышения точности выходных данных акселерометров на основе этого анализа.

1. Анализ температурных характеристик кварцевого гибкого акселерометра.

Результаты соответствующих исследований показывают, что температура оказывает два основных влияния на рабочую точность кварцевых гибких акселерометров:

1.1 Изменение магнитного поля

Некоторые внутренние магнитные поля акселерометров претерпевают незначительные изменения в зависимости от температуры внешней рабочей среды, что приводит к неточным масштабным коэффициентам акселерометров. В то же время может также произойти дрейф нуля, и даже собственные параметры системы, такие как коэффициент демпфирования и модуль упругости, также могут слегка дрейфовать с температурой.

1.2 Текущее изменение

Катушка крутящего момента во время работы генерирует ток обратной связи, вызывая повышение температуры катушки из-за теплового эффекта тока. Это изменение температуры катушки, в свою очередь, сделает распределение температуры внутри корпуса счетчика неравномерным, что приведет к изменениям параметров магнитного материала, что в конечном итоге отразится на масштабном коэффициенте.

Кроме того, с ростом температуры увеличивается и площадь катушки, что приводит к увеличению магнитного потока, окружающего катушку, т. е. к увеличению нелинейной погрешности. Наконец, опорный рычаг также может подвергнуться деформации, что приведет к повторному дрейфу датчика сигнала, а между тем изменение длины рычага или момента инерции также вызовет отклонение первоначального значения эффекта маятника, что приведет к серьезному дрейфу. в масштабном коэффициенте.

Таким образом, изменения температуры будут влиять на параметры внутреннего магнитного поля и структуру сердечника кварцевых гибких акселерометров, что в конечном итоге проявляется в дрейфе масштабных коэффициентов и нулевых смещениях акселерометров, тем самым вызывая ошибки вывода.

Рис.2 Распределение выходной ошибки акселерометра из-за изменения температуры
2. Решение проблемы влияния температуры на кварцевый гибкий акселерометр.

В настоящее время в практическом проектировании для снижения влияния температуры рабочей среды на кварцевый гибкий акселерометр обычно применяют следующие методы совершенствования:

2.1 Существенный аспект

Рассмотрите возможность использования материалов, нечувствительных к температуре с точки зрения материала, и улучшите тепловую конструкцию инерционных устройств, чтобы снизить чувствительность всей системы к температуре. Например, использование компонентов с отрицательными температурными коэффициентами для компенсации или компенсации изменений материалов с положительным температурным коэффициентом в акселерометрах.

2.2 Математическая модель компенсации

Качественно и количественно проанализировать температурные характеристики инерционных устройств для создания математической компенсационной модели, отвечающей определенным требованиям точности. На основе результатов математических расчетов с помощью программных алгоритмов может быть выполнена компенсация отклонений, вызванных изменением температуры, в реальном времени.

2.3 Улучшение рабочей среды акселерометра

Улучшение рабочей среды акселерометров для минимизации колебаний температуры во время работы, например, использование аппаратных структур с постоянной температурой для работы в среде с постоянной температурой.

Рис.3 Структурная схема системы контроля температуры кварцевого акселерометра

Первый метод улучшения в основном направлен на улучшение с точки зрения материалов и конструкции конструкции. Целью исследования является фундаментальное выявление причин температурного дрейфа акселерометра и соответствующие решения. В настоящее время многие исследователи и технические специалисты провели соответствующие исследования по этому вопросу.

Второй метод улучшения рассматривает и совершенствует с точки зрения алгоритмов программного обеспечения. Он создает относительно сложную модель математической компенсации температуры посредством качественного и количественного анализа экспериментальных данных для выполнения компенсации в реальном времени ошибок, вызванных изменениями температуры. На современном этапе многие эксперты и ученые также обсуждают и исследуют эти вопросы.

В акселерометре ER-QA-03C используется датчик температуры, и на его основе операторы могут компенсировать отклонения и масштабные коэффициенты для снижения влияния температурных факторов.

Рис.4 Малогабаритный кварцевый акселерометр для аэрокосмической отрасли
Рис.4 Кварцевый акселерометр ER-QA-03C для аэрокосмической отрасли
Последний метод улучшения контролирует изменения температуры через внешние аппаратные структуры, главным образом, чтобы заставить акселерометры работать в замкнутой среде с постоянной температурой, чтобы изолировать влияние внешних неопределенных условий.

По сравнению с первыми двумя методами, которые имеют такие недостатки, как сложная конструкция, длительный цикл и высокая стоимость, третий метод аппаратного контроля температуры не только имеет низкую стоимость и простоту реализации, но также обладает высокой универсальностью при сохранении высокой точности, поэтому он был широко используется в инженерной практике в стране и за рубежом.

1. Резюме

В данной статье анализируется влияние температуры на кварцевые гибкие акселерометры и соответствующие решения. Изменения температуры в основном влияют на параметры внутреннего магнитного поля и ток акселерометров, приводя к дрейфу масштабных коэффициентов и нулевым смещениям, тем самым вызывая ошибки вывода. Для решения этой проблемы предлагаются такие решения, как улучшение материалов, математические модели компенсации и улучшение рабочей среды.

В частности, упомянутый ранее ER-QA-03C имеет размеры Ф18,2х23 мм с масштабным коэффициентом 1,0±0,2 мА/г. Повторяемость смещения нулевой точки серии ER-QA-03C1 составляет ≤15 мкг, а повторяемость масштабного коэффициента составляет ≤15 ppm. Помимо аэрокосмических приложений, его также можно использовать для измерения статического и динамического ускорения.

Буду признателен, если вы обнаружите, что эта статья вам очень помогла. Прочтите следующие статьи и продукты, чтобы получить дополнительную информацию о кварцевом гибком акселерометре.