Motor Controller Torque Ratio Adjustment for Steering Feel
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Solution Overview
Problem
Existing motor control systems for assisting steering operations can disrupt the driver's feel by generating high responsiveness during lane keep control and target follow control, leading to a wrong or abrupt steering experience when the system intervenes.
Innovation Solution
A motor controller that includes an assist controller and a follow controller, with an intervention detector and restrictor, adjusts the ratio of assist torque to auto-steering torque based on driver intervention, preventing counteracting torque and reducing wind-up effects by restricting integration values within a motor driver circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high responsiveness is provided for lane keep control and target follow control, then the system can quickly correct deviations and ensure robustness, but the driver experiences a wrong feeling due to counteracting torque when interrupting the control
Solution Approach 1:
The patent dynamically adjusts the responsiveness of the follow control based on detected driver intervention. When driver intervention is detected, the system reduces the responsiveness (gain) of the follow control, allowing the driver's steering operations to take precedence. This dynamic adjustment resolves the contradiction by maintaining high responsiveness for system stability during normal operation while reducing it to preserve natural steering feel during driver intervention.
Solution Approach 2:
The system changes the control parameter (gain or responsiveness coefficient) based on the detected state. During normal lane keep control, a higher gain provides robust correction. When driver intervention is detected, the gain is reduced to prevent counteracting torque. This parameter change approach allows the system to adapt its behavior to resolve the contradiction between reliability and ease of operation.
2Speed
If the follow control quickly steers the steering wheel toward the target control value, then the target follow control achieves high responsiveness, but the abrupt automatic steering leaves a wrong feeling for the driver
Solution Approach 1:
The system dynamically adjusts the speed at which the follow control steers toward the target value based on driver intervention detection. During normal operation, the system can operate at high speed for quick correction. When driver intervention is detected, the system reduces the steering speed to provide smooth, natural-feeling assistance rather than abrupt automatic steering.
Solution Approach 2:
The system preemptively reduces the aggressiveness of the follow control when driver intervention is anticipated or detected, preventing the abrupt steering action before it occurs. This preliminary anti-action ensures that the high responsiveness does not manifest as abrupt, unsettling movements when the driver is actively steering.
3Productivity
If the lane keep control generates deviation cancelling torque with high responsiveness, then the vehicle quickly returns to the target lane, but the torque counteracts the driver's steering operation
Solution Approach 1:
The system dynamically adjusts the strength of the deviation cancelling torque based on detected driver intervention. During normal lane keep control, high responsiveness provides fast lane correction. When driver intervention is detected, the system reduces or suspends the deviation cancelling torque to avoid counteracting the driver's deliberate steering operations, thereby maintaining ease of operation while preserving the capability for fast correction when needed.
Data Source
AI summary
A motor controller has an assist controller that generates an assist instruction AC to generate an assist torque for lightening a steering load based on a detected value of a steering torque, and a follow controller obtaining a target value of a physical quantity regarding a steering operation and generating a follow instruction TC of a follow control. Further, an intervention detector in the motor controller detects an intervention of a driver or of a system, and a restrictor restricts an internal value that is used by the assist controller or by the follow controller, so that a ratio of the assist torque against the automatic steering torque is changed, which makes it possible to switch a control to the driver or to a system without a causing a wrong feeling to the driver.