Steering Motor Control with Hands-On Coefficient Switching
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Solution Overview
Problem
Existing motor control devices struggle with inconsistent reaction force characteristics during steering intervention and return characteristics after releasing the steering wheel, depending on circumstances due to the design prioritization of spring constant and viscous damping coefficients.
Innovation Solution
A motor control device that includes a hands-on/off determination unit to differentiate between gripping and released states, allowing individual setting of reaction force and return characteristics by adjusting coefficients in the equation of motion, such as inertia, spring constant, and viscous damping coefficient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spring constant and viscous damping coefficient are designed with priority given to the return characteristic, then the return characteristic (convergence to zero) is improved, but the reaction force characteristic during steering intervention becomes inconsistent and depends on circumstances
Solution Approach 1:
The patent applies dynamics by making the equation of motion coefficients changeable based on driving mode. The control unit switches between different coefficient sets (first coefficients for manual driving mode, second coefficients for autonomous driving mode), allowing the system to adapt its characteristics dynamically according to the current operating condition, thereby resolving the contradiction between return characteristic and reaction force characteristic consistency
Solution Approach 2:
The patent directly implements parameter changes by modifying the coefficients in the equation of motion based on the determined driving mode. The control unit changes at least one coefficient among the spring constant, viscous damping coefficient, or inertia moment according to whether the vehicle is in manual or autonomous driving mode, enabling independent optimization of reaction force and return characteristics for each mode
2Force
If spring constant and viscous damping coefficient are designed with priority given to the reaction force characteristic during steering intervention, then the reaction force characteristic is improved, but the return characteristic after releasing the steering wheel becomes inconsistent and depends on circumstances
Solution Approach 1:
The system dynamically adjusts the equation of motion coefficients based on the detected driving mode. When manual driving mode is detected, first coefficients are applied to optimize reaction force characteristic; when autonomous driving mode is detected, second coefficients are applied to ensure proper return characteristic. This dynamic switching resolves the contradiction by allowing each mode to have optimized parameters
Solution Approach 2:
The control unit changes the parameters (spring constant, viscous damping coefficient, or inertia moment) in the equation of motion according to the driving mode determination. This parameter change enables the system to provide appropriate reaction force characteristics during manual intervention while ensuring reliable return to center position when the driver releases the steering wheel in autonomous mode
Data Source
AI summary
A motor control device includes a manual steering command value generation unit that generates a manual steering command value, and a hands-on/off determination unit that determines whether a driver is in a gripping state in which the driver is gripping a steering wheel or in a released state in which the driver is not gripping the steering wheel. The manual steering command value generation unit is configured to generate the manual steering command value based on an equation of motion. The motor control device further includes a coefficient value changing unit that changes a value of at least one coefficient among coefficients included in the equation of motion based on a determination result from the hands-on/off determination unit.