Steer-by-Wire Garage Mode for Road Wheel Positioning
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Solution Overview
Problem
Steer-by-wire steering systems face challenges in calibration and towage due to the lack of mechanical coupling between the steering wheel and road wheels, necessitating improved control methods.
Innovation Solution
A garage mode is introduced in the steer-by-wire steering system, allowing the feedback actuator to be switched off, and the road wheel actuator to be positioned or fixed, enabling maintenance, calibration, and towage operations by controlling the road wheel actuator through external requests via vehicle communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a steer-by-wire steering system is used, then new possibilities for vehicle steering control are provided, but difficulties arise with respect to calibration and towage operations
Solution Approach 1:
The system performs preliminary actions by automatically positioning the road wheels in predetermined positions (such as straight-ahead position) before calibration or towage operations begin. The controller receives external requests and proactively adjusts the road wheel actuator to appropriate positions, eliminating the need for manual positioning during these special operations.
Solution Approach 2:
An external interface device serves as an intermediary between the operator and the steering system. This device allows external requests to be transmitted to the controller, enabling calibration and towage operations to be initiated and controlled externally without requiring direct mechanical access to the steering components.
2Reliability
If the feedback actuator remains active during maintenance operations, then steering feedback is maintained, but the road wheel actuator cannot be freely positioned for calibration and towage
Solution Approach 1:
The system dynamically changes the operational state of the feedback actuator based on the current mode. During garage mode (calibration, towage, maintenance), the feedback actuator is switched off to allow free positioning of the road wheels. When garage mode is terminated, the feedback actuator is automatically switched back on to restore normal steering feedback. This dynamic switching resolves the contradiction between maintaining feedback and enabling free positioning.
3Manufacturing precision
If the road wheel actuator is manually positioned during calibration, then calibration can be performed, but the process is time-consuming and complex
Solution Approach 1:
The system replaces manual mechanical positioning with automated electronic control. The controller receives external requests and automatically commands the road wheel actuator to move to precise predetermined positions using electronic signals, eliminating the need for manual mechanical adjustment. This substitution maintains calibration precision while significantly reducing the time and complexity of the calibration process.
Data Source
AI summary
A method to control a steer-by-wire steering system of a road vehicle including a feedback actuator, a road wheel actuator, and a controller configured or programmed to control the feedback actuator and the road wheel actuator, and the method includes, upon external request to the controller, providing a garage mode of the steer-by-wire system, switching off the feedback actuator, depending on the external request, moving to a predetermined position or moving from a first end position to a second end position of the road wheel actuator or fixing a position of the road wheel actuator at a last position or a center position, and, after the garage mode is terminated, returning the road wheel actuator to an original position before the garage mode was entered into and switching on the feedback actuator.