Four-Wheel Independent Steering for Accurate Parallel Movement
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Solution Overview
Problem
In four-wheel independent steering vehicles, there is a challenge in accurately aligning the wheels for parallel movement due to the independent control of each wheel, leading to errors and the need for additional driver steering to correct wheel alignment.
Innovation Solution
A system and method that includes a steering angle sensor, motor controller, and processor to set a parallel movement mode, adjust wheel positions, and limit steering angles within a specified range, using a position controller to assist in wheel alignment and prevent excessive steering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the four wheels are controlled independently with larger rotation angle ranges, then the vehicle can perform parallel movement and in-place rotation, but wheel alignment errors occur during parallel movement requiring additional driver steering
Solution Approach 1:
The system continuously monitors the actual wheel angles through sensors and compares them with target angles calculated by the controller. Based on this feedback, the controller adjusts the wheel angles in real-time to compensate for alignment errors and maintain precise parallel movement, resolving the contradiction between versatile maneuverability and alignment precision
Solution Approach 2:
The system dynamically changes the steering angles of the four wheels based on the selected movement mode (parallel movement, in-place rotation, or conventional driving). By adjusting the parameter ranges and target values of wheel angles according to different operational requirements, the system achieves both high adaptability and precise control
2Manufacturing precision
If the steering angle is limited to a range, then accurate parallel movement is achieved, but the driver's steering operation flexibility is reduced
Solution Approach 1:
The steering angle limits are not fixed but dynamically adjusted based on the detected steering mode. In parallel movement mode, the system applies stricter angle limits to ensure accuracy, while in conventional driving modes, the full steering range is available to the driver, thus maintaining both precision and flexibility
3Ease of operation
If collective wheel adjustment mode is set, then wheel positions are aligned, but distortion error occurs making accurate parallel movement impossible
Solution Approach 1:
Instead of adjusting all four wheels collectively, the system segments the control into individual wheel adjustments. Each wheel's angle is independently calculated and controlled based on its specific position and the desired movement trajectory, preventing the distortion errors that occur with collective adjustment while maintaining ease of operation through automated control
Data Source
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Figure 3A~3B
AI summary
Disclosed herein are a system and method for controlling four-wheel independent steering vehicles. The system includes a steering angle sensor configured to detect a steering angle in relation to movement of a steering wheel, a motor controller configured to changes a position of a wheel in response to the steering angle, a parallel movement key configured to set a parallel movement mode, and a processor configured to primarily adjust the position of the wheel through the motor controller by setting the parallel movement mode in response to the input of the parallel movement key and to control the motor controller to secondarily adjust the position of the wheel in response to the steering angle by limiting the steering angle of the steering wheel to a range of a limit angle. Therefore, it is possible to prevent the steering angle from changing significantly.