Steering Motor Control Switching for Real Road Feel
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Solution Overview
Problem
Existing motor control devices fail to accurately convey the actual road surface conditions to the driver, leading to discomfort due to the use of virtual road load in generating manual steering commands.
Innovation Solution
A motor control device that integrates manual and automatic steering command values, utilizing assist torque and manual steering command values, and switches between control modes based on a switching signal to enhance driver feedback on road conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the manual steering command value is generated by considering virtual road load, then the control system can operate smoothly, but the driver cannot feel the actual road surface condition
Solution Approach 1:
The patent segments the steering control into two independent command values: manual steering command value (preserving road feel) and automatic steering command value (ensuring control smoothness). This segmentation allows each component to fulfill its specific function without compromising the other, resolving the contradiction between smooth operation and road surface feedback.
Solution Approach 2:
The patent introduces an intermediary mechanism that processes actual road load torque through disturbance observation and separately integrates it into the manual steering command value. This intermediary approach allows the system to maintain smooth operation while preserving authentic road surface condition feedback for the driver.
2Measurement precision
If the disturbance torque is subtracted from the basic torque command value, then the control precision is improved, but the driver cannot feel the actual road surface condition
Solution Approach 1:
The patent separates the disturbance torque compensation function from the manual steering command generation. The disturbance observer calculates road load torque precisely for control accuracy, while this information is independently integrated into the manual steering command value to preserve road feel, resolving the contradiction between precision and feedback.
Solution Approach 2:
The patent creates a copy of the road load torque information through disturbance observation and uses it in two different ways: one copy for precise control calculation (subtraction from basic torque) and another copy for preserving road feel (integration into manual steering command). This copying approach allows both precision and feedback to coexist.
3Device complexity
If the electric motor is controlled based on the manual steering command value generated by considering virtual road load, then the control system is simplified, but the steering comfort is reduced
Solution Approach 1:
The patent divides the control system into distinct functional blocks: disturbance observer, manual steering command value generation unit, and integration unit. This segmentation maintains system simplicity while enabling authentic road load feedback to be incorporated, thereby preserving steering comfort without excessive complexity.
Data Source
AI summary
A motor control unit includes: an assist torque command value generation unit that generates an assist torque command value using steering torque; a manual steering command value generation unit that generates a manual steering command value using the steering torque and the assist torque command value; an integrated angle command value calculation unit that calculates an integrated angle command value by adding the manual steering command value to an automatic steering command value; and a switching unit that switches between a first control for controlling an electric motor based on the assist torque command value and a second control for controlling the electric motor based on the integrated angle command value, based on a switching signal.