SBW Reaction Torque Compensation for Oversteer and Understeer
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Solution Overview
Problem
Existing steer-by-wire (SBW) systems face challenges in controlling reaction torque effectively, leading to disturbances in the driver's counter-steer during over-steer or under-steer phenomena.
Innovation Solution
A device and method that include a yaw rate estimator, a vehicle state determinator, and a target torque compensator. The yaw rate estimator calculates the vehicle's yaw rate using vehicle speed and rack position data. The vehicle state determinator compares this estimate with detected yaw rates to determine if the vehicle is in an over-steer or under-steer state, and the target torque compensator adjusts the target torque based on this determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the SBW system provides active return function to assist steering wheel restoration, then steering wheel return to center is improved, but reaction torque control accuracy deteriorates due to torque components interfering with feedback
Solution Approach 1:
The patent segments the reaction torque into multiple components: basic reaction torque from steering angle, active return torque for center restoration, and counter-steer torque for slip compensation. By calculating and controlling each torque component separately, the system achieves both stable steering wheel return and precise reaction torque control without interference between functions.
2Reliability
If the system compensates for over-steer and under-steer phenomena, then vehicle trajectory accuracy is improved, but control system complexity increases
Solution Approach 1:
The patent implements feedback control by detecting actual yaw rate, comparing it with target yaw rate, and calculating counter-steer torque based on the difference. This feedback mechanism automatically compensates for over-steer and under-steer phenomena, improving trajectory accuracy while maintaining manageable control complexity through algorithmic rather than hardware-based solutions.
3Measurement precision
If the system calculates and applies counter-steer torque to compensate for vehicle slip, then steering precision is improved, but calculation complexity and processing time increase
Solution Approach 1:
The patent calculates counter-steer torque in real-time based on current yaw rate detection and target yaw rate, applying the compensation proactively during vehicle operation. This preliminary action approach maintains steering precision by continuously adjusting for slip conditions without requiring complex post-processing or lengthy calculations.
Data Source
AI summary
The present document relates to a device and method for controlling a reaction torque of an SBW system, which may include a yaw rate estimator for estimating a yaw rate of a vehicle, a vehicle state determinator for comparing a detection result of a yaw rate detection sensor and a yaw rate estimate which is estimated by the yaw rate estimator to determine whether the vehicle is in an under-steer or over-steer state, and a target torque compensator for compensating for a target torque by using an index which is a determination result of the vehicle state determinator and outputting a final target torque.