Steering Spring Torque Control for Vehicle Override
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Solution Overview
Problem
In vehicle steering systems with electric power steering and driving support devices, the existing control methods face challenges in maintaining the property of steered wheels to follow a target steered angle without compromising the operability of override steering in automatic steering mode, as the gain of feedback control affects both the steering reaction force and the ability to follow the target angle.
Innovation Solution
A steering reaction force control apparatus that adjusts the target steering spring force based on the actual steering operation amount, with a controller calculating and modifying the target steering spring force when the driving support device is operating, ensuring the magnitude of the steering spring force is appropriate to improve the alignment with the target steered angle without interfering with override steering operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the gain of feedback control is set to a high value by making a steering spring torque be large in magnitude, then the property of steered wheels to follow the target steered angle is improved, but the operability of override steering deteriorates
Solution Approach 1:
The patent applies dynamics by making the feedback gain variable rather than constant. The control gain is dynamically adjusted based on the operating mode (automatic steering vs. manual steering) and the magnitude of steering operation. This allows the system to have high gain during automatic steering for precise following, and low gain during manual override for ease of operation, thus resolving the contradiction between precision and operability.
Solution Approach 2:
The patent changes the parameter of feedback gain based on operating conditions. Specifically, the steering spring torque parameter is adjusted according to the absolute value of steering operation amount and the current mode. This parameter adaptation allows the system to optimize performance for different operational requirements, improving both following property and override operability under different conditions.
2Ease of operation
If the gain of feedback control is set to a low value by making a steering spring torque be small in magnitude, then the operability of override steering is secured, but the property of steered wheels to follow the target steered angle deteriorates
Solution Approach 1:
The system dynamically switches between low gain mode during manual override operations and high gain mode during automatic steering. This dynamic adjustment ensures that when the driver needs to override, the steering feels light and responsive, while during automatic operation, the wheels precisely follow the target angle.
Solution Approach 2:
The feedback gain parameter is changed based on the detected steering operation magnitude and mode. When override operation is detected (large steering input), the gain is reduced to improve operability. When automatic steering is active with normal operations, the gain is increased to improve following property.
Data Source
AI summary
Provided is a steering reaction force control apparatus for a vehicle including a driving support device configured to control an electric power steering device via a controller so that a steered angle of steered wheels reaches a target steered angle. When the driving support device is operating, the controller calculates a target steering spring torque based on a corrected steering angle corrected by a target steering angle for driving support control. When the magnitude of the corrected steering angle is less than a reference value, the target steering spring torque is calculated so that the magnitude of the target steering spring torque becomes larger in a case where the driving support device is operating compared with a case where the driving support device is not operating.