Steering Motor Control Using Virtual Spring Feedback
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Solution Overview
Problem
Existing motor control systems in vehicles experience adverse effects on driver steering feel due to self-aligning torque and driving assistance forces, particularly when the vehicle deviates from a target travel line, leading to deteriorated steering experience during straight travel.
Innovation Solution
A motor control device that calculates a manual steering command value using a reference model of the steering device, incorporating virtual spring and damper reaction forces from both manual and automatic steering inputs, to improve steering feel in driving assistance modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If driving assistance force is applied to return the vehicle to the target travel line, then the vehicle positioning accuracy is improved, but the driver's steering feel deteriorates
Solution Approach 1:
The patent introduces a virtual spring reaction force as an intermediary element to mediate between the automatic steering command value and the driver's steering input. This virtual spring reaction force is calculated based on the deviation angle and added to the manual steering command value, effectively filtering out the harmful self-aligning torque while preserving the driver's steering feel. The virtual spring acts as a buffer that translates the driving assistance force into a more driver-friendly form.
Solution Approach 2:
The patent changes the parameter of the virtual spring reaction force based on the deviation angle from the target travel line. By dynamically adjusting the virtual spring reaction force according to the deviation angle, the system can adaptively balance the driving assistance force with the driver's steering input, improving both vehicle positioning accuracy and steering feel under different driving conditions.
2Stability of the object's composition
If self-aligning torque is used to return the steering angle to zero degrees, then the steering system stability is improved, but the driver's steering feel is adversely affected in driving assistance mode
Solution Approach 1:
The patent converts the harmful self-aligning torque into a beneficial virtual spring reaction force. Instead of allowing the self-aligning torque to directly affect the driver's steering feel, the system uses the deviation angle information to calculate a virtual spring reaction force that compensates for the self-aligning torque's adverse effects. This transforms the harmful self-aligning torque into a useful component that improves vehicle positioning while maintaining steering feel.
Solution Approach 2:
The patent implements a feedback mechanism where the deviation angle from the target travel line is continuously monitored and fed back into the virtual spring reaction force calculation. This feedback loop allows the system to dynamically adjust the virtual spring reaction force based on the actual steering conditions, ensuring that the self-aligning torque is consistently compensated while maintaining steering system stability.
Data Source
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AI summary
A motor control device includes: a manual steering command value calculation unit that calculates a manual steering command value using torsion bar torque; 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 for driving assistance; and a control unit that controls drive of an electric motor based on the integrated angle command value. The manual steering command value calculation unit is configured to, in a driving assistance mode, calculate the manual steering command value using an equation of motion of a reference model of the steering device. The manual steering command value calculation unit calculates the manual steering command value using, as a virtual spring reaction force in the equation of motion, a virtual spring reaction force obtained by adding a virtual spring reaction force according to the automatic steering command value to a virtual spring reaction force according to the manual steering command value.