Steering Motor Control with Guarded Torque Split for Smooth Handling
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Solution Overview
Problem
Existing motor control devices restrict driver steering when a guard process is performed on the torque command value, leading to a sticking sensation in the steering torque.
Innovation Solution
A motor control device that includes a first assist torque command value setting unit, a manual steering command value generation unit, an integrated angle command value calculation unit, a second assist torque command value setting unit, an angle control unit, a subtraction unit, a guard processing unit, and a control unit to manage torque command values, ensuring driver steering is not restricted during guard processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a guard process is performed on the torque command value obtained by the angle control unit, then the reliability of the control system is improved, but the driver's steering is restricted causing a sticking sensation
Solution Approach 1:
The torque command value is segmented into two distinct components: a first torque command value derived from angle control (subject to guard process) and a second torque command value derived from assist torque control (exempt from guard process). This segmentation allows the guard process to ensure reliability for automatic steering while preserving steering smoothness for manual operation by not applying artificial limits to the driver's direct torque input.
Solution Approach 2:
The control unit acts as an intermediary that selectively applies the guard process only to the automatic steering component (first torque command value) while leaving the manual steering component (second torque command value) unmodified. This intermediary approach ensures that reliability measures do not interfere with the natural steering feel, as the driver's torque input is not subjected to artificial limiting.
2Adaptability or versatility
If the manual steering command value is included in the angle control unit together with the automatic steering command value, then the integrated steering control is achieved, but the driver's steering is restricted when guard process is performed
Solution Approach 1:
The integrated steering control is segmented into two separate command value generation paths: one for automatic steering (subject to guard process) and one for manual steering (exempt from guard process). This segmentation enables the system to maintain integrated control capability while differentiating the treatment of each component to avoid restricting the driver's steering input.
Solution Approach 2:
Different quality of control is applied to different components of the integrated steering system. The automatic steering component receives guard process treatment for safety, while the manual steering component receives no guard process treatment to preserve steering smoothness. This local differentiation resolves the contradiction between integrated control and steering freedom.
3Reliability
If an upper limit is set on the absolute value of the torque command value, then the control safety is improved, but the driver feels sticking in the steering torque
Solution Approach 1:
The torque command value is segmented into automatic steering component (with upper limit) and manual steering component (without upper limit). This segmentation allows safety limits to be applied only where necessary (automatic steering) while eliminating the harmful sticking sensation in manual steering by not imposing artificial limits on the driver's direct torque input.
Solution Approach 2:
The potential harm of unrestricted torque command values is converted into benefit by selectively applying guard process only to the automatic steering component. This converts the limitation into a beneficial selective safety measure that protects against automatic steering errors while preserving natural manual steering characteristics, thereby eliminating the sticking sensation.
Data Source
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AI summary
A motor control device includes: a manual steering command value generation unit that generates a manual steering command value using steering torque and a first 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; an angle control unit that calculates a first integrated torque command value according to the integrated angle command value; a subtraction unit that calculates a second integrated torque command value by subtracting a second assist torque command value from the first integrated torque command value; a guard processing unit that calculates a third integrated torque command value by performing a guard process on the second integrated torque command value; an addition unit that calculates a fourth integrated torque command value by adding the second assist torque command value to the third integrated torque command value; and a control unit that controls the electric motor based on the fourth integrated torque command value or the second assist torque command value.