Torque Vectoring Control for Vehicle Stability
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Solution Overview
Problem
Existing vehicle control systems face challenges in effectively managing oversteer and understeer conditions during cornering, particularly in two-wheel drive vehicles, where increased longitudinal slip reduces lateral force capacity, leading to stability issues.
Innovation Solution
A torque vectoring system and method that distribute torque between the left and right non-driven wheels based on calculated slip values and yaw moment changes, using a controller to determine torque control values from received speed values and slip calculations to counteract understeer and oversteer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If torque is applied to the driven wheels during cornering, then the vehicle can maintain propulsion force, but the longitudinal slip of the tires increases and lateral force capacity is reduced, causing understeer or oversteer
Solution Approach 1:
The patent segments the torque distribution control into two independent parts: the driven wheels (front or rear) and the non-driven wheels (rear or front). By independently controlling torque to non-driven wheels based on slip detection, the system can compensate for lateral force loss on driven wheels without affecting propulsion, thus resolving the contradiction between maintaining power and ensuring stability
Solution Approach 2:
The system continuously monitors longitudinal slip values of driven wheels and uses this feedback to dynamically adjust torque distribution to non-driven wheels. When slip exceeds a threshold indicating reduced lateral force capacity, the controller automatically modifies torque vectoring to counteract the resulting understeer or oversteer, maintaining vehicle stability while preserving propulsion
2Reliability
If a traditional torque vectoring mechanism is used to counteract understeer or oversteer, then vehicle stability can be improved, but the system complexity increases
Solution Approach 1:
The patent makes the non-driven wheels serve a dual function: their primary propulsion function and an additional function as a torque vectoring mechanism for stability control. By using the same wheels and existing differential components for both purposes, the system achieves active stability control without adding complex dedicated torque vectoring hardware, thus improving stability while minimizing increased device complexity
3Measurement precision
If torque is distributed to non-driven wheels to counteract slip, then handling precision is improved, but the device complexity increases
Solution Approach 1:
The system uses the vehicle's existing wheel speed sensors and differential mechanism to provide slip detection and torque distribution functions. The non-driven wheels' differential action naturally responds to torque imbalances, and the controller leverages this self-service capability to achieve precise handling control without requiring additional complex mechanical torque vectoring components
Data Source
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AI summary
A method of controlling a torque vectoring mechanism and an associated torque vectoring system are disclosed. The method can distribute torque between a left non-driven wheel and a right non-driven wheel of a vehicle based on a torque control value. The torque control value can be based on a change in yaw moment about a center of gravity of the vehicle. The change in yaw moment can be determined based on a reduction of lateral force on a driven axle due to both longitudinal and lateral slip on the driven wheels.