EPS Steering Control Rate Adjustment
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Solution Overview
Problem
Existing driver assistance systems for vehicles using electric power steering devices face challenges in controlling the rate of change of the actual steering angle when resuming automated steering control after a driver's intervention, leading to potential discomfort due to sudden vehicle behavior.
Innovation Solution
A driver assistance system that includes both automated steering control and steering angle return control, where the system adjusts the rate of change of the actual steering angle to be lower than during steering angle return control, using calculated correction terms and gain values to ensure a smoother transition to the target steering angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a large lane keeping assist torque is applied when the deviation of the actual steering angle becomes greater, then the automated steering control can quickly correct the steering angle to approach the target steering angle, but the rate of change of the actual steering angle may increase excessively causing driver discomfort
Solution Approach 1:
The patent applies dynamics by making the target steering angle speed variable rather than fixed. The control section dynamically adjusts the target steering angle speed based on the absolute value of the steering angle speed, creating a speed-dependent control mechanism that adapts to different operating conditions and resolves the contradiction between quick correction and driver comfort
Solution Approach 2:
The patent changes the parameter of target steering angle speed based on the actual steering angle speed. When the absolute value of actual steering angle speed exceeds a threshold, the target steering angle speed is reduced, thereby controlling the rate of change to prevent excessive steering angle variation and driver discomfort while still allowing effective automated steering control
2Extent of automation
If the automated steering control resumes after driver intervention, then the system can maintain automated operation, but the sudden application of large steering torque may cause abrupt vehicle behavior
Solution Approach 1:
The patent applies beforehand cushioning by pre-establishing a speed-dependent control mechanism that cushions against abrupt vehicle behavior. When the actual steering angle speed is high (indicating potential abrupt behavior), the system automatically reduces the target steering angle speed, providing a cushioning effect that prevents sudden vehicle movements while maintaining automated control resumption
Solution Approach 2:
The patent implements feedback by continuously monitoring the actual steering angle speed and using it to adjust the target steering angle speed. This closed-loop feedback mechanism ensures that when automated steering control resumes after driver intervention, the system can detect high steering angle speeds and automatically reduce the target speed to maintain stable vehicle behavior
Data Source
AI summary
A driver assistance system for a vehicle executes, as steering control using an EPS device, automated steering control for causing an actual steering angle of a wheel to approach a target steering angle and steering angle return control for returning the actual steering angle to a neutral point in response to a steering operation by a driver being ended during non-automated steering control. Under comparison in a condition where a first angle difference is equal to a second angle difference, the driver assistance system is configured, in reverting to the automated steering control after a steering intervention of the driver is performed during the automated steering control and causing the actual steering angle to approach the target steering angle, to change the actual steering angle with a change rate that is lower than that in returning the actual steering angle to the neutral point during the steering angle return control.