Steering Torque Threshold Control for ASIL-D Safety
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional steering systems in vehicles face challenges in ensuring safe motor torque control, particularly in meeting the stringent ASIL-D safety integrity level requirements, especially when operating in closed-loop control systems.
Innovation Solution
A method is introduced that dynamically adjusts torque thresholds by setting first and second upper and lower torque thresholds based on vehicle sensor information. This method allows for the summation of consecutive torque requests within specific ranges and compares them to a summed-up torque limit, adjusting the thresholds to ensure safe operation and detect potential malfunctions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional open-loop control with safety limiter applied after each function component is used, then ASIL-D safety requirements are met, but device complexity increases and ease of operation decreases
Solution Approach 1:
The patent merges multiple safety limiter functions into a single integrated safety limiter that processes all torque requests through one unified control path. Instead of applying separate safety limiters after each function component (open-loop approach), the invention combines them into one closed-loop system that sums torque requests first, then applies a single safety limiter, reducing complexity while maintaining ASIL-D safety assurance.
Solution Approach 2:
The patent implements closed-loop control by feeding back the summed torque request to the safety limiter, which dynamically adjusts torque thresholds based on actual system state. This feedback mechanism allows the safety limiter to adaptively manage torque requests while maintaining safety requirements, simplifying the overall control architecture compared to static open-loop limiting.
2Reliability
If traditional open-loop control with individual safety limiters is implemented, then each function's safety is ensured, but the overall system requires higher ASIL-D implementation complexity
Solution Approach 1:
The patent creates a universal safety limiter that handles multiple function types (basic assistance, active damping, active return, ADAS, HAD) through a single unified control path. This multi-functional safety limiter processes torque requests from all sources using the same safety logic and thresholds, eliminating the need for separate safety limiters for each function and reducing controller implementation complexity while maintaining comprehensive safety coverage.
3Adaptability or versatility
If closed-loop control with summed torque request is used, then control flexibility improves, but achieving ASIL-D safety requirements becomes more difficult
Solution Approach 1:
The patent implements dynamic torque threshold adjustment within the closed-loop control system. The safety limiter dynamically modifies upper and lower torque thresholds based on real-time conditions while maintaining ASIL-D safety integrity. This dynamic adaptation allows the system to flexibly respond to varying operational requirements without compromising safety compliance, as the thresholds are adjusted within predefined safe boundaries.
Solution Approach 2:
The patent changes torque request parameters dynamically by adjusting upper and lower torque thresholds based on summed torque requests and system state. This parameter adjustment mechanism allows closed-loop control flexibility while ensuring that modified parameters still meet ASIL-D safety requirements, resolving the contradiction between adaptability and safety compliance.
Data Source
Figure 1A~1B
Figure 2
Figure 3~4
AI summary
A method of controlling motor torque in a vehicle comprises receiving torque requests; determining first upper and lower torque thresholds based on vehicle sensor information; determining second upper and lower torque thresholds; if consecutive torque requests are received that are between the first and the second upper torque threshold or between the first and the second lower torque threshold, summing up over time the consecutive torque requests between the first the second upper torque thresholds or between the first and the second lower torque thresholds to find a summed-up torque value; and if the summed-up torque value exceeds a summed-up torque limit, adjusting the second upper torque threshold and/or the second lower torque threshold. The first upper and torque thresholds are indicative of a range of allowable torque, and the second upper and lower torque thresholds set upper and lower limits which the motor torque cannot exceed.