Vehicle Steering Control Switching for Low-Speed Path Stability
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Solution Overview
Problem
In automated driving, vehicles experience steering angle variability and overshoot at low velocities, leading to weaving or meandering due to increased steering angle commands as the vehicle slows down.
Innovation Solution
A vehicle control system that adjusts steering angle control based on vehicle velocity, switching between control methods to maintain stability by reducing steering angle commands when velocity is low, using feedback control and model estimation to prevent overshoot.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If feedback control calculates vehicle behavior command to increase steering angle control amount as velocity decreases, then the vehicle can follow the travel target accurately at low velocity, but the steering angle fluctuates and causes weaving or meandering
Solution Approach 1:
The patent applies dynamics by making the steering angle control amount dynamically adjustable based on vehicle velocity. The control system switches between two different control characteristics: at high velocity, it uses normal feedback control with standard steering angle control amount; at low velocity, it transitions to a different control mode with reduced steering angle control amount. This dynamic adaptation resolves the contradiction by adjusting the control gain according to operating conditions, preventing steering angle fluctuations and weaving while maintaining tracking accuracy across different velocity ranges.
2Measurement precision
If the steering angle control amount increases as velocity decreases to maintain tracking accuracy, then the vehicle can follow the travel target at low velocity, but overshoot occurs in steering angle control
Solution Approach 1:
The patent applies parameter changes by modifying the steering angle control amount parameter based on vehicle velocity. When velocity exceeds a predetermined threshold, the system uses a first steering angle control command with normal control gain. When velocity falls at or below the threshold, it switches to a second steering angle control command with reduced control gain. This parameter change prevents overshoot and improves control reliability while maintaining the ability to follow the travel target accurately at low velocities.
3Device complexity
If the vehicle uses a single steering angle control command for all velocities, then the control system is simple, but it cannot prevent weaving or meandering at low velocity
Solution Approach 1:
The patent applies segmentation by dividing the velocity range into two segments: high velocity (above threshold) and low velocity (at or below threshold). Each segment has its own optimized steering angle control command. This segmentation allows the system to use different control strategies for different operating conditions, preventing weaving and meandering at low velocity while maintaining simplicity through clear threshold-based switching logic.
Data Source
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AI summary
A vehicle control device, a vehicle control method, and a vehicle control system according to the present invention perform feedback control to reduce difference in lateral direction or difference in turning direction between an own vehicle and a travel target, so as to acquire a first steering angle control command for increasing a steering angle control amount as the velocity of the own vehicle decreases, acquire a second steering angle control command for decreasing the steering angle control amount with respect to the velocity, compared with a magnitude of the steering angle control amount with respect to the velocity obtained by the first steering angle control command, output the first steering angle control command when the velocity is greater than a predetermined threshold, and output the second steering angle control command when the velocity is equal to, or less than, the predetermined threshold.