Steer-by-Wire Feedback Torque Subtraction for Stability
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Solution Overview
Problem
Steer-by-wire systems lack effective haptic feedback and can experience steering vibrations due to misinterpretation of feedback torque as driver input, leading to unstable steering control.
Innovation Solution
A steer-by-wire system that includes a steering mechanism, sensors, power electronics, an electric servomotor, and an actor for generating feedback torque, where the feedback torque is subtracted from the driver's hand torque to prevent misinterpretation, allowing for precise control and haptic feedback management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback torque is generated at the steering means based on steering rack position, then haptic feedback is provided to the driver, but the feedback torque is misinterpreted as driver input causing steering vibrations and instability
Solution Approach 1:
The patent extracts the feedback torque component from the total torque signal measured by the torque sensor. By separating and removing the feedback torque portion from the driver's hand torque signal before processing, the system prevents the feedback torque from being misinterpreted as additional driver input, thereby eliminating the cause of steering vibrations and instability
Solution Approach 2:
The patent introduces an intermediary processing step in the control unit that acts as a mediator between the torque sensor and the steering control algorithm. This intermediary subtracts the calculated feedback torque from the measured total torque, creating a corrected driver input signal that accurately represents only the driver's steering intent without contamination from the feedback mechanism
2Reliability
If an actor generates feedback torque at the steering means, then haptic feedback is restored, but the system complexity increases due to additional components and control loops
Solution Approach 1:
The patent merges the feedback torque calculation and subtraction functionality directly into the existing steering control unit, rather than adding a separate dedicated system. The control unit performs both the calculation of feedback torque based on steering rack position and the subtraction of this torque from the sensor signal, consolidating multiple functions within a single control module to minimize system complexity
Data Source
AI summary
The invention relates to a steer-by-wire system, that includes a steering mechanism, a sensor for detecting a driver request, a steering control device, power electronics, an electric servomotor, a steering rack that can be moved by the servomotor and an actor for generating a feedback torque (MFF) at the steering mechanism as a function of a steering rack position, wherein the steering control unit is configured in such a way so as to subtract, based on the feedback torque (MFF), at least a portion from a driver request determined based on sensor data, and a method for operating a steer-by-wire system.