Steering Wheel Control for Automated Driving Path Adherence
Solution Overview
Problem
Existing automated driving systems face challenges in maintaining ease of operation and vehicle stability when a driver performs a steering operation during automated driving, particularly when passing obstacles, as they apply large reaction forces to the steering wheel, leading to unstable vehicle behavior and reduced driver ease.
Innovation Solution
An automated driving apparatus and system that include a steering operation detection unit, target steering angle setting units, and a steering wheel control unit to adjust the steering wheel's rotation angle based on detected steering operations, gradually decreasing the reaction force after the operation ends, and asymptotically approaching the initial target steering angle, enhancing driver ease and vehicle stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large reaction force is applied to the steering wheel to return the host vehicle to the set traveling path, then the vehicle returns to the desired path, but the ease of operation by the driver is reduced and the behavior of the host vehicle becomes unstable
Solution Approach 1:
The reaction force applied to the steering wheel is made dynamic rather than static. The control unit adjusts the magnitude of the reaction force based on the driver's steering operation intensity. When the driver applies significant force (indicating intentional steering input), the system reduces the reaction force to avoid conflict and instability. When driver input is minimal, the system applies stronger reaction force to maintain the set traveling path. This dynamic adjustment resolves the contradiction between maintaining path accuracy and ensuring operational ease.
Solution Approach 2:
The system changes the parameter of reaction force magnitude based on detected steering operation characteristics. By monitoring steering torque or angular velocity, the system identifies when the driver is actively steering and adjusts the reaction force parameter accordingly - reducing it during active steering and increasing it during passive following. This parameter change strategy allows the system to maintain reliability when needed while preserving ease of operation when the driver intervenes.
2Reliability
If the device continues to apply a large reaction force to the steering wheel after the host vehicle has passed the obstacle, then the vehicle remains on the set traveling path, but the behavior of the host vehicle becomes unstable
Solution Approach 1:
The system employs feedback control by continuously monitoring the host vehicle's position relative to the set traveling path and the driver's steering operations. When the vehicle has successfully passed the obstacle and returned to the desired path, the feedback signal indicates that large reaction force is no longer needed. The control unit responds by reducing the reaction force, thereby maintaining path adherence through subtle corrections rather than aggressive steering interventions, thus preserving vehicle behavior stability.
Solution Approach 2:
The reaction force application is made time-dependent and condition-dependent. The system dynamically adjusts the force magnitude based on the current driving context - applying strong force only when necessary to correct path deviations caused by obstacles, and gradually reducing the force as the vehicle stabilizes on the correct path. This dynamic approach prevents the instability that would result from continuous aggressive correction.
Data Source
AI summary
A steering wheel control unit executes control such that a steering wheel rotates in accordance with a first target steering angle and the steering wheel rotates in accordance with a second target steering angle when a steering operation is detected. A target steering angle setting unit sets the second target steering angle that asymptotically approaches an actual steering angle from the first target steering angle with the lapse of time, during a period from when the steering operation is detected during the automated driving until when an end of the steering operation is detected, and sets the second target steering angle that asymptotically approaches the first target steering angle with the lapse of time after the end of the steering operation is detected. After the steering operation takes place, the reaction force gradually decreases. After the steering operation ends, the reaction force gradually increases.