Steering System Torque Adjustment for Actuator Failure
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Solution Overview
Problem
Existing steering systems fail to ensure operational safety and provide adequate assistance torque, particularly during safety-critical driving situations and actuator path failures, which can lead to loss of vehicle control, especially in heavy vehicles.
Innovation Solution
A method and steering system that dynamically adjust assistance torque by deactivating or reducing it based on driving situations, using two actuator paths where one can take over from the other, ensuring controllability even in failures, and adjusting torque levels based on vehicle speed and steering dynamics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If assistance torque is permanently reduced to ensure driver control during failures, then vehicle controllability is improved, but steering assistance is insufficient during normal operations
Solution Approach 1:
The steering system dynamically adjusts the assistance torque based on real-time monitoring of actuator path status and driving conditions. When both actuator paths are functional, full assistance torque is provided. When one actuator path fails, the system detects this and reduces the assistance torque to a safer level, thereby maintaining driver control while preserving full assistance during normal operations
Solution Approach 2:
The system changes the torque parameter based on system state. The control unit monitors the functionality of actuator paths and adjusts the assistance torque parameter accordingly - using 100% assistance when both actuators work, and reduced assistance when one fails, thus resolving the contradiction between full assistance and safe control
2Reliability
If assistance torque is reduced to prevent loss of control during actuator failure, then safety is improved, but driver support in critical situations is worsened
Solution Approach 1:
The system applies different quality levels of assistance torque to different driving situations. In normal driving conditions, reduced assistance torque ensures safety. In critical driving situations detected by the control unit, full assistance torque is restored to provide necessary driver support, thus resolving the contradiction between safety and driver support
3Ease of operation
If 100% assistance torque is provided by second actuator path during first actuator failure, then steering support is improved, but vehicle controllability is worsened due to excessive direction change
Solution Approach 1:
Instead of providing 100% assistance torque through the second actuator path (excessive action), the system provides a reduced level of assistance torque (partial action). This partial assistance is sufficient to help the driver with steering but limited enough to prevent excessive direction changes that would compromise vehicle controllability
Data Source
AI summary
The disclosure relates to a method for operating a steering system of a motor vehicle having a power steering system. A support torque is introduced into a steering transmission. A driving situation is determined. The support torque is reduced depending on the driving situation.