Steer-by-Wire Steering Angle Control at Standstill
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Solution Overview
Problem
Steer-by-wire steering systems face high power requirements and component wear due to increased steering torques when a vehicle is at a standstill, leading to inefficient steering behavior and rapid component degradation.
Innovation Solution
A method to maintain a substantially constant wheel steering angle at standstill and adjust it to a target angle only when the vehicle starts moving, using a wheel steering angle controller with a computing unit to determine the target angle based on steering demand and vehicle trajectory, thereby reducing power requirements and component load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the wheel steering angle is adjusted according to steering demand while the vehicle is at a standstill, then the steering responsiveness is improved, but the power requirement and component load increase significantly
Solution Approach 1:
The control unit determines a target wheel steering angle in advance based on the steering demand, but the actual adjustment is delayed until the vehicle starts moving. This preliminary determination without immediate execution allows the system to prepare for steering while avoiding the high torque requirements of steering at standstill, thus maintaining responsiveness without excessive power consumption.
2Measurement precision
If the wheel steering angle is adjusted according to steering demand while the vehicle is at a standstill, then the steering precision is improved, but the component wear increases due to high steering torques
Solution Approach 1:
The control unit calculates and stores the target wheel steering angle before the vehicle moves, ensuring steering precision is prepared in advance. The actual steering adjustment occurs only after the vehicle starts moving, which eliminates the high torque conditions that cause component wear during standstill steering operations.
Solution Approach 2:
The system dynamically adjusts the steering angle only when the vehicle is in motion, adapting the steering control to the dynamic conditions of moving vehicles. This dynamic approach avoids the static high-torque conditions of standstill steering while maintaining precise steering control during actual vehicle operation.
3Power
If the wheel steering angle is kept constant at standstill, then the power requirement and component load are reduced, but the steering behavior deteriorates
Solution Approach 1:
The control unit determines the target wheel steering angle in advance based on the steering demand, preparing the steering system for upcoming maneuvers. This preliminary calculation ensures that when the vehicle starts moving, the steering angle can be adjusted immediately and precisely to the pre-calculated target, maintaining good steering behavior without the power consumption of continuous adjustment at standstill.
Data Source
AI summary
A method is for controlling a wheel steering angle of at least one vehicle wheel of a vehicle, in particular of a motor vehicle. The vehicle has a steer-by-wire steering system including at least one wheel steering angle control element, which is provided at least for modifying the wheel steering angle of the vehicle wheel according to a steering demand. In at least one operating mode, in which the vehicle is at a standstill and a steering demand is received, the wheel steering angle of the vehicle wheel is at least substantially maintained at a constant value and a desired wheel steering angle for the vehicle wheel is determined in accordance with the steering demand. In at least one subsequent additional operating mode, in which the vehicle is moving, the wheel steering angle is adjusted to the desired wheel steering angle by the wheel steering angle control element.