Differential Cooperative Active Steering Torque Fluctuation Control
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Solution Overview
Problem
The integration of Active Front-Wheel Steering (AFS) systems with Differential-Drive-Assist-Steering (DDAS) in electric-wheel-independent-drive vehicles causes instantaneous fluctuations in steering wheel torque, leading to unsafe driving conditions and incorrect driver feedback on road information due to interference with the steering angle and yaw moment.
Innovation Solution
A differential cooperative active steering system with a planetary gear mechanism and independent wheel drive systems, coupled with revised control strategies for AFS and DDAS, to suppress steering gain characteristics and stabilize steering wheel torque, ensuring accurate steering and driver feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If AFS system intervenes to improve steering characteristics, then steering flexibility is improved, but instantaneous fluctuations in steering wheel torque occur causing unsafe driving conditions
Solution Approach 1:
The control method uses feedback from steering angle sensors and torque sensors to continuously monitor the steering system state. The AFS control module adjusts the auxiliary steering angle based on feedback from the steering wheel torque and steering angle, thereby suppressing instantaneous torque fluctuations while maintaining steering flexibility.
Solution Approach 2:
The patent introduces an intermediary control module that coordinates between AFS and DDAS systems. This intermediary controller processes steering requests from both systems and generates coordinated control signals, preventing direct interference between AFS steering angle intervention and DDAS torque control, thus eliminating torque fluctuations while preserving steering adaptability.
2Adaptability or versatility
If AFS system intervenes to improve steering characteristics, then steering flexibility is improved, but driver perception of road information becomes incorrect
Solution Approach 1:
The control system uses feedback from steering angle sensors to monitor the actual steering wheel angle. The DDAS control module calculates reference steering wheel torque based on this feedback and adjusts differential drive torques accordingly, ensuring that torque fluctuations do not distort driver perception of road conditions while AFS maintains its steering flexibility benefits.
3Ease of operation
If DDAS system applies drive torque difference to achieve steering assistance, then steering assistance is provided, but yaw moment changes affect steering gain characteristics
Solution Approach 1:
The coordinated control module acts as an intermediary that decouples the effects of DDAS torque application from steering gain characteristics. It calculates the relationship between differential torques and steering angle, and adjusts AFS auxiliary steering angle to compensate for DDAS-induced yaw moment changes, thereby maintaining stable steering gain while preserving steering assistance functionality.
Solution Approach 2:
The control method dynamically adjusts the auxiliary steering angle parameter based on the differential torque applied by DDAS. By changing this parameter in real-time according to the relationship between differential torques and steering angle, the system compensates for yaw moment effects and maintains stable steering gain characteristics while DDAS provides steering assistance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system ensures quick and accurate centering of front wheels, automatic state determination, reduced interference between AFS and DDAS, and stable steering characteristics, allowing drivers to correctly perceive road information and reduce torque fluctuations.
Implementation Method 1
a planetary gear mechanism, comprising: a first input end, a second input end and an output end, wherein the output end is connected to the steering rack and drives the steering rack to generate lateral displacement
Data Source
AI summary
A differential cooperative active steering system for a front-axle independent-drive vehicle with electric wheels includes a steering rack which is arranged between a first steering wheel and a second steering wheel, and is able to generate lateral displacement and pull the first and second steering wheels to steer; a planetary gear mechanism, including a first input end, a second input end and an output end; a steering angle coupling motor, connected to the first input end; and an input shaft of the steering wheel, connected to the second input end. The planetary gear mechanism can realize the coupling between an input steering angle of an input shaft of the steering wheel and an input steering angle of the steering angle coupling motor. In addition, a method for controlling the differential cooperative active steering system is provided.