Yaw Motion Control for Four-Wheel Distributed Vehicles
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Solution Overview
Problem
Traditional center-driven electric vehicles lack effective control over yaw stability, especially during steering, due to differential speed and torque between left and right drive wheels, which limits vehicle handling and steering control.
Innovation Solution
A hierarchical control method for four-wheel distributed vehicles that includes white noise filtering, estimation of sideslip angle using a magic formula tire model and Luenberger observer, calculation of yaw moments through a two-track two-degree-of-freedom nonlinear vehicle model, and distribution of driving forces to four drive motors using an optimization algorithm to maintain yaw stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional center-driven differential control is used, then the vehicle can maintain differential speed between left and right drive wheels, but the yaw stability control is insufficient especially during steering
Solution Approach 1:
The patent segments the drive system into four independently controlled drive wheels, allowing individual torque control of each wheel. This enables precise yaw moment generation by creating torque differences between left and right wheels or between front and rear wheels, thereby improving yaw stability and steering control without relying on passive differential mechanisms
Solution Approach 2:
The patent dynamically adjusts the torque parameter distributed to each drive wheel based on vehicle operating conditions (steering angle, yaw rate, lateral acceleration). By changing the torque parameter in real-time according to actual driving scenarios, the system achieves effective yaw stability control and enhanced steering performance
2Adaptability or versatility
If four-wheel distributed drive system is used, then independent control of each drive wheel is achieved, but the control complexity increases
Solution Approach 1:
The patent implements a feedback control mechanism that continuously monitors vehicle state parameters (yaw rate, lateral acceleration, steering angle) and adjusts the torque distribution to each drive wheel accordingly. The feedback loop compares actual vehicle behavior with desired behavior and modifies torque commands to achieve optimal yaw stability and steering control, managing the complexity through intelligent control algorithms
Solution Approach 2:
The patent employs dynamic torque distribution strategies that adapt to changing vehicle conditions. The control system dynamically calculates optimal torque values for each wheel based on real-time parameters such as steering angle, vehicle speed, and yaw rate, allowing the system to handle diverse driving scenarios while maintaining manageable control complexity through model-based control approaches
Data Source
AI summary
A yaw motion control method for a four-wheel distributed vehicle includes: calculating the steering response of the vehicle in a steady state using a nonlinear vehicle model in reference with an understeering degree while constraining by the limit value of the road surface adhesion condition according to the sideslip angle response and the vertical load change in the steady state, calculating the lateral force response and the self-aligning moment response of the tires in the steady state by a magic tire formula, calculating the required additional yaw moment by using the yaw motion balance equation, reasonably distributing the generalized control force to the four drive motors through the optimization algorithm in combination with the current driving conditions; finally, off-line storing and retrieving the calculation results of the off-line distribution of different vehicle parameters required by different upper layers to distribute the torques to the four drive wheels.