Steer-By-Wire Emergency Steering Using Torque Vectoring
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Solution Overview
Problem
Existing steer-by-wire steering systems face challenges in accurately reproducing the original driving behavior during emergency steering operations, particularly when mechanical auxiliary systems are not used.
Innovation Solution
A method that incorporates a torque vectoring system to distribute drive and braking torques to individual wheels, enabling precise control of front and rear wheel steering angles to maintain the original vehicle direction and behavior, even in the event of actuator failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical auxiliary systems are provided for emergency steering operation, then the steering function is maintained during faults, but the space requirements, mounting complexity, and structural impairment increase
Solution Approach 1:
The patent replaces mechanical auxiliary steering systems with an electrically operated emergency steering system. The control device detects steering wheel position and generates steering signals that are transmitted to the steered wheels via electric actuators, eliminating the need for mechanical backup systems while maintaining steering functionality during faults.
Solution Approach 2:
The control device serves multiple functions: it normally controls steering during regular operation and automatically activates emergency steering mode when a fault is detected. The same electrical system handles both normal and emergency steering operations, eliminating the need for separate mechanical auxiliary systems.
2Device complexity
If a completely electrically operating emergency steering system is used, then space and mounting complexity are reduced, but the accuracy of reproducing original driving behavior deteriorates
Solution Approach 1:
The control device continuously monitors the actual steering behavior and compares it with the desired emergency steering behavior. Based on this feedback, the control device adjusts the steering signals to minimize deviations from the original driving behavior, ensuring accurate reproduction even in emergency mode.
Solution Approach 2:
The emergency steering system dynamically adapts its control parameters based on the detected fault condition and current driving situation. The control device modifies steering characteristics in real-time to maintain optimal reproduction of original driving behavior under varying emergency conditions.
Data Source
AI summary
A method for controlling a steer-by-wire steering system for a motor vehicle having steerable front and rear wheels in emergency steering operation comprises checking the steering system for the presence of a fault state and performing the emergency steering operation to maintain original driving behaviour if a fault state is detected, including: determining a target lateral acceleration on the basis of a current steering wheel position and a current vehicle speed, determining a yaw moment and, from the yaw moment, a general wheel steering angle for the original driving behaviour, where the general wheel steering angle is equal to a difference between a front wheel steering angle and a rear wheel steering angle, determining a front wheel steering angle correction and a rear wheel steering angle correction, and determining drive torques and/or braking torques for the front wheels and the rear wheels, which are distributed appropriately by the torque vectoring system.