Steer-By-Wire Turning Control for Actuator Drive Limits
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Solution Overview
Problem
Existing turning control systems for vehicles with independently turning wheels fail to ensure appropriate vehicle controllability when the drive of any turning actuator is restricted, particularly in vehicles with three or more wheels, due to the lack of coordinated control between actuators and reaction force actuators.
Innovation Solution
A turning control device that includes multiple turning actuator control units and a reaction force actuator control unit, which communicate drive limit information to limit the actuators' drive based on shared information such as steering angle and current limits, ensuring coordinated control and maintaining vehicle stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the drive of a turning actuator is restricted due to malfunction, then the reliability of the turning system deteriorates, but the vehicle controllability must be maintained
Solution Approach 1:
The control device receives feedback information from detection devices that monitor the operational status of each turning actuator. Based on this feedback, the control device determines whether any actuator is malfunctioning and adjusts the target turning angles accordingly to maintain vehicle controllability while accounting for the restricted drive capability.
Solution Approach 2:
The control device dynamically adjusts the target turning angles of the other turned wheels based on the detected malfunction. When one actuator is determined to be malfunctioning, the control device modifies the turning angle commands for the remaining functional actuators in real-time to compensate for the loss and maintain appropriate vehicle controllability.
2Ease of operation
If the target turning angle of other turned wheels is switched when one actuator malfunctions, then the vehicle controllability is maintained, but the complexity of the control system increases
Solution Approach 1:
The control device is segmented into multiple independent control units, with each control unit responsible for controlling a specific turning actuator. This modular segmentation allows the system to independently manage each actuator's status and adjust individual target turning angles without requiring complex centralized control logic for the entire system.
Solution Approach 2:
Each control unit autonomously determines whether its corresponding turning actuator is malfunctioning by receiving feedback from detection devices and independently adjusts the target turning angle for that actuator. This self-service capability reduces the need for complex inter-unit communication and centralized decision-making, thereby reducing overall system complexity.
Data Source
AI summary
A turning control device controls a turning of each wheel in a vehicle in which three or more wheels that are not mechanically restricted from one another can be turned independently. Steering actuator control units are provided corresponding to a plurality of turning actuators that turn the respective wheels, and control a drive current so that a turning angles output by the turning actuators become desired values. A reaction force actuator control unit controls a drive of a reaction force actuator in a steering mechanism of a steer-by-wire system. The turning actuator control units and the reaction force actuator control unit communicate a drive limit information, and limit the drive of the turning actuators and the reaction force actuator based on the drive limit information.