Steering Control Feedback Fixing for Road-Induced Oscillation
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Solution Overview
Problem
Steering control devices experience periodic movement of steering when a vehicle passes through road surface irregularities due to disturbances affecting the yaw rate sensor, leading to unstable vehicle behavior.
Innovation Solution
A steering control device with a feed-forward steering angle determination unit, feedback steering angle determination unit, and correction unit that performs feedback steering angle fixing control to correct the feedback steering angle to a fixed value when the yaw rate exceeds a target range and the steering angle periodically moves, thereby suppressing periodic steering movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If feedback steering angle is continuously adjusted based on yaw rate sensor output, then steering control responsiveness is improved, but periodic steering movements occur when vehicle passes through road surface irregularities
Solution Approach 1:
The patent applies periodic action by detecting when the steering angle periodically moves (oscillates between right and left directions) and temporarily suspending feedback steering angle adjustments during such periods. This prevents the control system from reacting to spurious oscillations caused by road irregularities, thereby maintaining steering stability while preserving responsiveness during normal conditions.
Solution Approach 2:
The patent enhances feedback by monitoring the steering angle's movement characteristics and using this information to modulate the feedback steering angle calculation. When periodic movement is detected, the system adjusts the feedback mechanism to exclude oscillatory components, ensuring that only meaningful steering deviations trigger corrections.
2Measurement precision
If target steering angle is calculated based on disturbed yaw rate sensor output, then steering control accuracy is improved, but vehicle steering becomes unstable and oscillates
Solution Approach 1:
The patent introduces an intermediary mechanism that filters out the effects of road surface irregularities from the yaw rate sensor output before it influences the target steering angle calculation. By detecting periodic steering movements and suspending feedback adjustments during these periods, the system acts as a mediator that prevents distorted sensor data from triggering unstable steering corrections.
Solution Approach 2:
The patent applies beforehand cushioning by detecting the onset of periodic steering movements and temporarily suspending feedback steering angle adjustments before the oscillations can cause significant vehicle instability. This preventive measure cushions against the harmful effects of road irregularities before they can fully manifest as unsafe steering behavior.
Data Source
AI summary
A steering control device includes: a feed-forward steering angle determination unit configured to determine a feed-forward steering angle corresponding to a target yaw rate; a feedback steering angle determination unit configured to determine a feedback steering angle based on a yaw rate detected by a yaw rate sensor and a steering angle detected by a steering angle sensor; a target steering angle determination unit configured to determine a target steering angle of a vehicle based on the feed-forward steering angle and the feedback steering angle; and a correction unit configured to perform feedback steering angle fixing control for correcting the feedback steering angle output to the target steering angle determination unit to a fixed value when the yaw rate detected by the yaw rate sensor exceeds a target yaw rate range including the target yaw rate and the steering angle detected by the steering angle sensor periodically moves.