Autonomous Navigation Yaw Frame Conversion for Kalman Convergence
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Solution Overview
Problem
Autonomous navigation systems using Kalman filters face challenges in accurately estimating attachment angles of six-axis inertial sensors, leading to slow convergence or divergence of estimated values, especially when the yaw angle exceeds ±90°, hindering proper calculation of a vehicle's state.
Innovation Solution
Incorporating a yaw angle detection unit and a conversion unit that converts the inertial sensor output to a virtual inertial sensor with a yaw angle within ±90°, allowing the Kalman filter to estimate the attachment angle accurately, and setting initial values based on detected yaw and pitch angles to prevent divergence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the Kalman filter is used to estimate the attachment angle of the inertial sensor, then the state of the moving body can be calculated, but the estimation converges slowly or diverges when the yaw angle exceeds ±90°
Solution Approach 1:
The system performs preliminary detection of the yaw angle using the inertial sensor before feeding data to the Kalman filter. When the yaw angle is detected to be within ±90°, the system proactively transforms the coordinate system and adjusts the initial value, preventing divergence before it occurs. This preliminary action ensures the Kalman filter operates within its reliable estimation range.
Solution Approach 2:
The system dynamically changes parameters based on the detected yaw angle. When the yaw angle exceeds ±90°, the system transforms the coordinate system and adjusts the initial value parameter of the Kalman filter to bring the effective yaw angle within the ±90° range. This parameter adjustment allows the Kalman filter to maintain reliable convergence while handling arbitrary sensor attachment angles.
2Adaptability or versatility
If the inertial sensor is attached at an arbitrary angle to the moving body, then the system is more adaptable to different installations, but the Kalman filter estimation may diverge
Solution Approach 1:
The system performs preliminary detection of the yaw angle using the inertial sensor before feeding data to the Kalman filter. When the yaw angle is detected to be within ±90°, the system proactively transforms the coordinate system and adjusts the initial value, preventing divergence before it occurs. This preliminary action ensures the Kalman filter operates within its reliable estimation range.
Solution Approach 2:
The system dynamically changes parameters based on the detected yaw angle. When the yaw angle exceeds ±90°, the system transforms the coordinate system and adjusts the initial value parameter of the Kalman filter to bring the effective yaw angle within the ±90° range. This parameter adjustment allows the Kalman filter to maintain reliable convergence while handling arbitrary sensor attachment angles.
3Ease of operation
If the yaw angle of the inertial sensor is exactly ±90° or exceeds it, then the sensor can be mounted in various orientations, but the Kalman filter cannot properly estimate the attachment angle
Solution Approach 1:
The system introduces a coordinate system transformation as an intermediary between the inertial sensor and the Kalman filter. When the detected yaw angle is ±90° or exceeds it, the transformation adjusts the angle to fall within the ±90° range, allowing the Kalman filter to accurately estimate the attachment angle. This intermediary transformation enables accurate estimation while maintaining ease of sensor mounting.
Data Source
AI summary
A sensor attachment angle detection unit detects a yaw angle A3 of an approximate attachment angle of a six-axis inertial sensor, and a sensor output conversion unit converts acceleration outputs (ax, ay, az) and angular velocity outputs (ωx, ωy, ωz) of three axes Xs, Ys, and Zs in a coordinate system of the six-axis inertial sensor into accelerations (ax′, ay′, az) and angular velocities (ωx′, ωy′, ωz) of three axes Xs′, Ys′, and Zs in the coordinate system having a yaw angle within ±45 according to an angle range to which the detected attachment angle A3 belongs and inputs the converted accelerations and angular velocities to a Kalman filter.