Motor Control Apparatus for Suppressing Vibrations via Compensation Filter
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Solution Overview
Problem
Conventional motor control systems face challenges in suppressing vibrations while maintaining precise path control, as techniques like notch filters and input shaping often result in residual vibrations and overshoot, causing deviations from the commanded path and degrading machining quality.
Innovation Solution
A motor control apparatus that includes a compensation filter with elements based on mechanical system constants (inertia, stiffness, and damping coefficients) to generate a compensated position command, allowing the motor to vibrate while keeping the machine stationary, thereby ensuring precise path control and effective vibration suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If notch filters or input shaping are used to suppress vibrations, then residual vibration is reduced, but the machine deviates from the commanded path due to overshoot
Solution Approach 1:
The control system is segmented into two independent control loops: a servo control loop for high-frequency response and stability, and a vibration suppression control loop for low-frequency resonance. Each loop handles different frequency ranges independently, allowing vibration suppression without affecting path accuracy in the servo control loop.
Solution Approach 2:
A dedicated vibration suppression controller acts as an intermediary between the position command generator and the servo controller. This intermediary processes the position command to generate a vibration suppression command that compensates for resonance effects before the command is executed by the servo system, preventing path deviation while suppressing vibrations.
2Manufacturing precision
If notch filters are used to cut resonance frequency energy, then residual vibration is reduced, but overshoot occurs causing traces on the workpiece
Solution Approach 1:
Instead of using notch filters to remove resonance frequency components from the command (which causes overshoot), the invention inverts the approach by adding a vibration suppression command that actively counteracts resonance. The vibration suppression controller generates a compensatory command based on the mechanical system's resonance characteristics, preventing overshoot while achieving vibration suppression.
Solution Approach 2:
The vibration suppression controller incorporates feedback from the mechanical system's resonance characteristics (natural frequency and damping ratio) to generate an appropriate suppression command. This feedback mechanism allows the system to adaptively counteract vibrations without causing the overshoot associated with notch filters, thereby preventing traces on the workpiece.
Data Source
AI summary
A motor control apparatus of the present invention is a motor control apparatus for compensating elastic deformation between a servo motor and a driven part, driven by the servo motor, which includes a position command generator for generating a position command of the motor, a compensation filter for compensating the position command generated by the position command generator and a servo control unit for controlling the movement of the motor based on a position command after compensation, i.e., the compensated position command by the compensation filter, and is constructed such that the compensation filter includes a filter F(s) having an inertia JL of the driven part, a stiffness coefficient K of an elastically deformable part and a damping coefficient C of the elastically deformable part as the elements of filter coefficients.