Motor Control Device Steering Angle Command Virtual Reaction Force
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Solution Overview
Problem
The range of steering torque detectable by a torque sensor is limited, restricting the ability of drivers to perform steering operations beyond the detection upper limit, as the target wheel steering angle is fixed once the maximum detectable torque is reached, preventing further steering adjustments.
Innovation Solution
A motor control device and method that includes a torque sensor and an electronic control unit, which generates a steering angle command value using an equation of motion and limits a virtual reaction force to prevent the equation from entering a steady state, allowing the steering angle command value to exceed the detectable range of the torque sensor or the maximum applied steering torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the steering angle command value is generated based on the steering torque detected by the torque sensor, then the steering control accuracy is improved, but the steering angle range is limited by the detection upper limit of the torque sensor
Solution Approach 1:
The patent changes the parameter of virtual reaction force from an unlimited value to a limited value within a specific range. By limiting the virtual reaction force to be smaller than the maximum possible driving torque, the system allows the steering angle command value to exceed the torque sensor's detection range while maintaining control accuracy through the modified equation of motion.
2Ease of operation
If the virtual reaction force is not limited in the equation of motion, then the steering angle command value can be calculated, but the equation of motion may enter a steady state that restricts further steering operations
Solution Approach 1:
The patent applies preliminary anti-action by preemptively limiting the virtual reaction force before the equation of motion can enter a steady state. This prevents the system from reaching a condition where further steering operations become impossible, thereby maintaining ease of operation throughout the entire steering range.
3Reliability
If the steering torque exceeds the maximum value the driver can apply, then the torque sensor detects the maximum value, but the target wheel steering angle is fixed and no further steering operation can be performed
Solution Approach 1:
The patent introduces a limiting mechanism on the virtual reaction force that acts as an intermediary between the torque sensor output and the steering angle command value. This intermediary ensures that even when the torque sensor reaches its maximum detection value, the system can still generate valid steering angle commands by controlling the virtual reaction force within appropriate bounds.
Data Source
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AI summary
A motor control device for controlling drive of an electric motor (18) that controls a steering angle of a steering device, the motor device includes: a torque sensor (12) and an electronic control unit (202). The torque sensor is configured to detect steering torque acting on a steering member (2). The electronic control unit is configured to: generate a steering angle command value (manual steering command value) based on the steering torque by using an equation of motion that is a reference model of the steering device; control driving of the electric motor (18) so that an actual steering angle follows the steering angle command value; and limit a virtual reaction force that is a reaction force component of the equation of motion.