Steering Control Reference Angle Compensation for Torque Stability
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Solution Overview
Problem
Existing steering control devices experience sudden fluctuations in required torque due to hysteresis when the increasing and decreasing directions of target lateral acceleration switch, affecting steering feel during automatic driving or driving assistance.
Innovation Solution
A steering control device that calculates a reference steering angle based on the target steering angle and vehicle speed, compensating for deviations to suppress sudden torque fluctuations by adjusting the reference steering angle to follow the target angle within a predetermined value, using a friction compensation unit to control the electric actuator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If friction compensation is performed using target lateral acceleration, then steering accuracy is improved, but required torque suddenly fluctuates when increasing and decreasing direction switches
Solution Approach 1:
The patent applies preliminary action by calculating a reference steering angle based on vehicle speed and target steering angle before friction compensation is applied. This reference steering angle is then used to determine the friction compensation amount in advance, preventing sudden torque fluctuations when the target lateral acceleration direction switches. The compensation unit determines whether the deviation between the reference steering angle and target steering angle is equal to or greater than a predetermined value, and compensates accordingly to smooth torque transitions.
2Ease of operation
If friction compensation is applied to maintain steering angle, then steering followability is improved, but torque fluctuation increases during direction switching
Solution Approach 1:
The patent implements feedback by continuously monitoring the deviation between the reference steering angle and target steering angle. The compensation unit uses this feedback information to determine when friction compensation should be applied. When the deviation is equal to or greater than a predetermined value, the system adjusts the reference steering angle to follow the target steering angle, thereby maintaining steering followability while preventing torque fluctuations during direction switching.
Data Source
AI summary
A steering control device that controls steering of a vehicle in which automatic driving or driving assistance is performed includes a reference steering angle calculation unit that calculates a reference steering angle of the vehicle based on a target steering angle and a vehicle speed of the vehicle, and a compensation unit that determines whether a deviation between the calculated reference steering angle and the target steering angle is equal to or greater than a predetermined value, and when determination is made that the deviation is equal to or greater than the predetermined value, compensates for the calculated reference steering angle such that the calculated reference steering angle follows the target steering angle.