Steering Control Apparatus Hysteresis Gain Adjustment
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Solution Overview
Problem
The existing steering control systems for vehicles, particularly when the follow-up steering function is engaged, often compromise driver controllability as the driver must generate a steering torque against the torque provided by the system, leading to an extreme driving feeling and reduced controllability when attempting to modify the vehicle's trajectory.
Innovation Solution
A control apparatus that calculates an adjusted command torque by applying an adjustment gain based on the steering torque, incorporating hysteresis characteristics to differentiate the torque response depending on whether the driver is steering normally or reversing, thereby enhancing driver controllability by modifying the torque generated by the motor in response to the driver's steering intentions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the torque given through the follow-up steering function is adjusted in accordance with the steering torque, then the driver's controllability is improved, but the enhancement of the performance of following the target trajectory and the enhancement of the controllability of the vehicle by the driver become incompatible with each other when the driver attempts to slightly modify the trajectory
Solution Approach 1:
The patent changes the parameter of adjustment gain based on the steering state (steering fixedly, steering normally, steering back, or hands-free state). By adapting the adjustment gain to different steering states, the system improves driver controllability when needed while maintaining target trajectory following performance during normal operation.
Solution Approach 2:
The system dynamically adjusts the adjustment gain according to the driver's steering state rather than using a fixed gain. This dynamic adaptation allows the torque adjustment to be optimized for each specific steering situation, resolving the contradiction between controllability enhancement and trajectory following performance.
2Reliability
If the adjustment gain is changed within such a range that changes in state quantity are small, then the performance of following the target trajectory is maintained, but the enhancement of the controllability of the vehicle by the driver is insufficient
Solution Approach 1:
The patent applies parameter changes by selecting different adjustment gain values based on the determined steering state. This allows significant changes in torque adjustment characteristics without causing large changes in state quantity, as the gain is adjusted discretely based on state classification rather than continuously.
Solution Approach 2:
The steering states are segmented into distinct categories (steering fixedly, steering normally, steering back, hands-free state), and each category has its corresponding adjustment gain. This segmentation allows the system to provide appropriate controllability enhancement for each state while maintaining overall trajectory following performance.
3Adaptability or versatility
If the driver generates a steering torque against the torque given through the follow-up steering function, then the driver can steer the vehicle in a desired direction, but the driver develops an extreme driving feeling and the controllability of the vehicle by the driver is reduced
Solution Approach 1:
The system uses feedback from the steering torque sensor to determine the driver's steering state and adjusts the adjustment gain accordingly. This feedback mechanism allows the system to recognize when the driver intends to steer in a desired direction and provides appropriate torque adjustment to improve controllability without creating extreme driving feelings.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution improves driver controllability by reducing the steering load and maintaining appropriate torque adjustments, allowing smoother steering operations without sudden changes, thus enhancing the vehicle's responsiveness to the driver's inputs.
Implementation Method 1
a motor 200 that is configured to generate the command torque Tc
Implementation Method 2
a steering torque sensor 22 that is configured to detect a steering torque T
Implementation Method 3
an adjusted steering torque Tr having predetermined hysteresis characteristics with respect to changes in the steering torque T
Data Source
AI summary
A control apparatus according to the present disclosure is configured to perform a process of calculating a command torque that is given to a steering mechanism, an adjustment gain calculation process in which an adjustment gain for the command torque is calculated based on a steering torque, a process of calculating an adjusted command torque obtained by applying the adjustment gain to the command torque, and a process of controlling the steering mechanism in accordance with the adjusted command torque. It should be noted herein that the adjustment gain calculation process includes a process of calculating an adjusted steering torque having predetermined hysteresis characteristics with respect to changes in the steering torque, based on the steering torque, and a process of converting the adjusted steering torque into the adjustment gain.