Steer-by-Wire Shimmy Compensation Using Rack Force Signals
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Solution Overview
Problem
Steer-by-wire steering control devices face challenges in compensating for shimmy vibration without a torque sensor, as conventional methods using torque signals can introduce phase delays and fail if the sensor is unavailable, affecting steering feel.
Innovation Solution
A steering control method and device that compensates for shimmy using the road wheel actuator-side rack force signal instead of the steering feedback actuator-side torque signal, employing shimmy compensation logic, rack force generation, and reaction force torque signal output to generate a shimmy compensation rack force and reaction force torque, even when the torque sensor fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shimmy compensation is performed using the torque signal from the torque sensor, then the shimmy frequency can be determined and shimmy vibration can be compensated, but phase delay occurs that negatively affects the steering feel
Solution Approach 1:
The patent introduces an intermediary approach by using the rack force signal as a mediator between the road wheel actuator and the shimmy compensation control. Instead of directly using the torque signal from the steering feedback actuator, the rack force signal serves as an intermediate measurement that correlates with shimmy vibration but without introducing the same phase delay problems, thus maintaining steering feel while enabling effective shimmy compensation
Solution Approach 2:
The patent substitutes the mechanical torque measurement system with an alternative measurement approach using rack force signal processing. By replacing the direct torque signal-based compensation method with a rack force signal-based method, the system achieves shimmy compensation without the phase delay issues inherent in the original mechanical feedback path
2Reliability
If the torque sensor is used for shimmy compensation, then shimmy can be compensated based on the torque signal, but the system fails to operate if the torque sensor fails
Solution Approach 1:
The patent extracts the shimmy compensation functionality from its dependency on the torque sensor by using the rack force signal instead. This extraction allows the shimmy compensation feature to operate independently of the torque sensor, maintaining system functionality even when the torque sensor fails or is removed
Solution Approach 2:
The patent makes the shimmy compensation system universal by enabling it to function using the rack force signal, which is already available in the steer-by-wire system for other control functions. This multi-functional use of the rack force signal allows the system to maintain shimmy compensation capability regardless of torque sensor status, improving overall system adaptability
Data Source
AI summary
The present embodiments may provide a steering control method and a steering control device capable of compensating for shimmy even when the torque sensor fails and removing only shimmy components without affecting the steering feel by compensating for shimmy using the road wheel actuator-side rack force signal, rather than the steering feedback actuator-side torque signal.