Dual Yaw Stability Control for Fail-Operational Vehicle Motion
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Solution Overview
Problem
Existing vehicle motion control systems, such as Yaw Stability Control (YSC), are not designed as safety critical systems, leading to increased risks of fatalities due to misuse and malfunction, especially in conditions like slippery roads or evasive maneuvers, and are inadequate for autonomous and electrified vehicles.
Innovation Solution
A fail-operational vehicle motion control system with dual YSC systems, one controlling steering and one controlling braking, utilizing independent or common sensor arrangements with redundancy and sensor fusion to ensure safety and reliability, adhering to safety standards like ISO 26262.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If YSC control is made smooth and comfortable, then driver comfort is improved, but drivers tend to increase speed and misuse YSC, resulting in increased fatalities
Solution Approach 1:
The system dynamically adjusts the control characteristics of YSC based on detected vehicle states and operating conditions. When instability is detected, the system transitions from a smooth comfort-oriented control to a more abrupt stability-oriented control, allowing the system to adapt its behavior to the situation rather than maintaining a fixed control characteristic
Solution Approach 2:
The system changes control parameters such as intervention threshold, control gain, and actuator command limits based on the detected level of instability and operating conditions. This allows the same YSC system to provide both comfortable smooth control during mild conditions and aggressive stability correction when needed
2Adaptability or versatility
If YSC capability is used to extend the limits of controllable driving, then path following capability is improved, but the vehicle becomes more susceptible to instabilities when YSC malfunctions
Solution Approach 1:
The system segments the YSC functionality into multiple independent control paths: primary YSC control, alternative control methods, and fallback procedures. This segmentation ensures that if one control path fails, other paths remain available to maintain basic vehicle stability and controllability
Solution Approach 2:
The system implements monitoring and diagnostic functions that detect potential malfunctions before they lead to complete failure. Warning systems and gradual degradation modes are prepared in advance to cushion the transition from normal operation to failure states, maintaining controllability throughout
3Productivity
If vehicles are made with less understeer behavior, then path following is improved, but the vehicle becomes more susceptible to oversteer instabilities
Solution Approach 1:
The system uses continuous feedback from sensors measuring yaw rate, lateral acceleration, wheel speeds, and steering angle to detect the onset of oversteer conditions. This feedback enables real-time detection and correction of instability while allowing the vehicle to maintain improved path following characteristics through reduced understeer
Data Source
AI summary
The present invention relates to a system for vehicle motion control (100) of a vehicle with at least a steering system and one or more of a brake system (24) and a torque vectoring system. a number of sensors (11.21) for sensing at least vehicle speed or wheel speed, yaw rate and wheel angle, said vehicle motion control system comprising a Yaw Stability Control (YSC) functionality comprising an oversteer control function, wherein the YSC function is arranged to be fail-operational.