Z-Axis Angular Velocity Sensor Bias Error Reduction
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Solution Overview
Problem
Inertia measurement devices used in vehicle positioning systems face challenges in achieving high accuracy for yaw angle measurements, as existing angular velocity sensors have similar bias errors, leading to lower accuracy compared to roll and pitch angle measurements.
Innovation Solution
The device incorporates X-axis, Y-axis, and Z-axis angular velocity sensors with specific bias error and Allan variance constraints, where the Z-axis sensor has a smaller bias error and Allan variance, ensuring higher accuracy for yaw angle measurements by configuring the Z-axis sensor with more sensor elements and using Si-MEMS technology for other sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the same specification angular velocity sensors are used for all three axes, then the manufacturing cost and device complexity are reduced, but the measurement precision of the yaw angle (Z-axis) is insufficient compared to roll and pitch angles
Solution Approach 1:
The patent applies local quality by assigning different performance specifications to different sensor axes based on their functional requirements. The Z-axis angular velocity sensor (for yaw angle measurement) is configured with stricter bias error and Allan variance requirements compared to the X-axis and Y-axis sensors. This localized differentiation of sensor quality ensures that the yaw angle measurement, which is critical for vehicle positioning accuracy, receives enhanced measurement precision without unnecessarily increasing the complexity of all sensor configurations.
2Measurement precision
If the Z-axis angular velocity sensor has higher precision requirements, then the yaw angle measurement accuracy is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent implements local quality by specifying that only the Z-axis angular velocity sensor requires higher precision manufacturing with stricter bias error and Allan variance constraints. The X-axis and Y-axis sensors can be manufactured with standard specifications. This approach allows the manufacturing process to focus resources on achieving high precision for the critical yaw angle measurement while maintaining ease of manufacture for the other sensors, thereby resolving the contradiction between measurement precision and manufacturing ease.
3Reliability
If more sensor elements are used in the Z-axis angular velocity sensor, then the bias error and Allan variance are reduced, but the device complexity and cost increase
Solution Approach 1:
The patent applies local quality by concentrating the increased sensor element quantity specifically in the Z-axis angular velocity sensor where it is most needed for reliable yaw angle measurement. The X-axis and Y-axis sensors can use fewer sensor elements since their measurement reliability requirements are less stringent. This localized increase in sensor element quantity improves the reliability of the angular velocity signal for the critical Z-axis while minimizing the overall device complexity and cost increase.
Data Source
AI summary
An inertia measurement device, which is used in combination with a satellite positioning receiver that outputs a positioning result at every T seconds in a positioning system equipped on a vehicle, when a Z-axis angular velocity sensor, a position error P[m] based on the detection signal of the Z-axis angular velocity sensor while the vehicle moves at a moving speed V[m/sec] for T seconds satisfies Pp≥P=(V/Bz)×(1−cos(Bz×T)) (where, a bias error of the Z-axis angular velocity sensor is Bz[deg/sec] and a predetermined allowable maximum position error during movement for T seconds is Pp[m]), and a bias error Bx and By of the Y-axis angular velocity sensor satisfies Bz<Bx and Bz<By.