IMU Yaw Error Detection via Pivot Turns
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Solution Overview
Problem
Inertial navigation systems face errors due to internal IMU inaccuracies and misalignment of the IMU with respect to the vehicle, which accumulate over time and affect navigation accuracy, particularly in applications requiring precise vehicle control like agriculture, where small yaw orientation errors can have significant economic consequences.
Innovation Solution
A method that uses left and right pivot turns at a constant speed to detect yaw orientation error without relying on GPS measurements or complex algorithms, utilizing existing IMU acceleration data to calculate the misalignment and incorporate it into the navigation solution, thereby improving accuracy and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If IMU measurements are integrated with respect to time to provide navigation solution, then continuous position and velocity information is obtained, but errors in the measurements accumulate over time reducing navigation accuracy
Solution Approach 1:
The patent implements feedback by using GPS position measurements to continuously correct and update the IMU-derived navigation solution. The system compares the IMU integrated position with GPS absolute position and uses the difference to adjust subsequent IMU calculations, preventing error accumulation while maintaining continuous navigation capability during periods without GPS signal.
2Ease of operation
If IMU is mounted on the vehicle to enable navigation, then vehicle motion can be tracked, but misalignment or orientation error between IMU and vehicle introduces additional errors
Solution Approach 1:
The patent applies preliminary action by performing orientation calibration procedures before normal navigation operation. The system executes specific maneuver sequences (such as pivot turns or figure-eight patterns) to determine the IMU's initial orientation relative to the vehicle, storing this calibration data for use during subsequent navigation operations to eliminate misalignment errors.
Solution Approach 2:
The patent replaces mechanical alignment procedures with computational methods. Instead of requiring precise physical mounting of the IMU to the vehicle, the system uses mathematical models and sensor fusion algorithms to calculate and compensate for orientation errors, substituting complex mechanical alignment requirements with software-based solutions.
3Measurement precision
If GPS measurements are used to correct IMU errors, then navigation accuracy is improved, but system reliability decreases when GPS signal is degraded or lost
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the navigation solution based on GPS signal quality. When GPS signal is strong, the system heavily weights GPS corrections. When GPS signal degrades or is lost, the system transitions to relying more on the IMU inertial solution with adjusted error growth models, maintaining navigation availability across all signal conditions.
4Measurement precision
If complex calibration procedures are implemented to eliminate IMU errors, then measurement precision improves, but device complexity and time required for setup increase
Solution Approach 1:
The patent applies partial action by implementing a tiered calibration approach. The system offers basic calibration procedures that provide sufficient accuracy for most applications, requiring minimal setup time and complexity. Advanced calibration options are available but not required for normal operation, allowing the system to achieve adequate precision without always requiring the most complex procedures.
Data Source
AI summary
Methods, apparatus, and systems for detecting and compensating for yaw orientation error or misalignment of an IMU in a vehicle navigation system. Acceleration measurements available from the IMU can be used for fast, reliable, and compact estimation of alignment error whether or not the IMU and fixed-body frames share an origin or not. The detection can be included in a navigation solution for guidance and control systems of a vehicle without having to utilize other measurements such as GPS.