Steer-by-Wire Wheel Angle Control for Bump Steer Compensation
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Solution Overview
Problem
Existing steer-by-wire systems fail to account for real-time steering angles and dynamic suspension characteristics, leading to excessive bump steer, which causes tire wear and reduced vehicle handling on uneven roads.
Innovation Solution
A system that includes sensors to measure steering and suspension dynamics, a processor to compute toe changes, and actuators to adjust wheel angles, aligning wheels to minimize bump steer and improve steering precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed steering geometry is used in steer-by-wire system, then the steering system structure is simple, but the vehicle drives less dynamically in specific driving environment and excessive bump steer occurs
Solution Approach 1:
The patent implements variable steering ratio that dynamically adjusts based on driving conditions. The control unit modifies the relationship between steering wheel angle and wheel angle in real-time, allowing the steering system to adapt to different driving environments such as low-speed maneuvering versus high-speed stability requirements, thereby resolving the contradiction between fixed simple structure and dynamic performance
2Ease of manufacture
If mechanical or by-wire toe alignment is set without considering real-time steering angle and suspension dynamics, then the alignment setup is simple, but excessive bump steer occurs causing tire wear and reduced handling
Solution Approach 1:
The control unit continuously receives feedback from sensors measuring steering wheel angle, wheel angle, and suspension deflection. Based on this real-time feedback, the system dynamically adjusts the toe alignment by modifying the steering ratio to compensate for bump steer effects, thereby eliminating excessive bump steer while maintaining simple alignment setup procedures
Solution Approach 2:
The patent replaces fixed mechanical toe alignment settings with an electronically controlled variable steering ratio system. Instead of using complex mechanical linkages to maintain fixed geometry, the system uses electronic control units and sensors to dynamically adjust alignment parameters, eliminating bump steer through electronic feedback rather than mechanical constraints
3Device complexity
If the steering ratio is uniformly maintained, then the control system is simple, but the vehicle does not drive dynamically in specific driving environment
Solution Approach 1:
The patent implements a variable steering ratio control system that dynamically changes the steering ratio based on driving conditions. The control unit adjusts the relationship between steering wheel input and wheel output in real-time, providing different steering characteristics for different driving scenarios such as low-speed parking maneuvers versus high-speed highway driving, thereby achieving dynamic adaptability without excessive control system complexity
Data Source
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AI summary
Proposed are an apparatus for controlling a steer-by-wire system and a method of controlling a steer-by-wire system. The apparatus and the method are capable of adjusting respective steering angles of wheels and eliminating bump steer, taking into consideration the real-time steering angles and dynamic characteristics of a suspension and a rack. Thus, ride quality and steering precision can be improved by individually controlling the wheels, minimizing a toe change in a situation where the wheels are under different loads and minimizing an influence of the uneven road surface. Moreover, the frequency with which damage to a front wheel steering and the suspension occurs can be reduced, operation of a steering wheel can be readily performed during cornering, and fuel efficiency can be improved with less tire wear.