Servo Controller Selection for Vibration Suppression in Low-Rigidity Machines
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Solution Overview
Problem
Existing positioning control devices for low-rigidity machines face challenges in shortening positioning time while suppressing vibrations, with pre-filter techniques leading to prolonged command times and discontinuous actuator operation causing vibrations, and lack of clear guidelines for control loop switching resulting in lengthy adjustments.
Innovation Solution
A positioning control device incorporating a first and second servo controller, residual vibration information management, and predictive amplitude analysis to selectively use controllers based on operation conditions, ensuring efficient positioning within desired error limits and minimizing vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a pre-filter is used to suppress residual vibrations, then vibration suppression is improved, but the command time period is prolonged
Solution Approach 1:
The patent applies dynamics by making the pre-filter characteristics variable rather than fixed. The pre-filter transfer function is dynamically adjusted based on the movement distance of the machine tool. For longer movements, a stronger vibration suppression filter is applied, while for shorter movements, a weaker filter is used to minimize time delay. This dynamic adaptation resolves the contradiction between vibration suppression and command response time.
2Object-affected harmful factors
If the position control loop characteristics are switched during positioning control, then vibration suppression is improved, but the actuator operation becomes discontinuous causing vibrations
Solution Approach 1:
The patent applies parameter changes by smoothly varying the pre-filter transfer function parameters based on movement distance rather than abruptly switching control loop characteristics. The pre-filter transfer function parameters are continuously adjusted according to the movement distance, which avoids discontinuous actuator operation while still achieving vibration suppression. This resolves the contradiction by maintaining actuator operation continuity while suppressing vibrations.
3Device complexity
If a pre-filter independent of movement distance is used, then vibration suppression is simplified, but the positioning time is prolonged for short movements
Solution Approach 1:
The patent applies dynamics by making the pre-filter characteristics variable based on movement distance. Instead of using a fixed pre-filter independent of movement distance, the system dynamically selects or adjusts the pre-filter transfer function according to the actual movement distance. This resolves the contradiction by adapting the filter strength to match the movement requirements, preventing excessive positioning time delays for short movements while maintaining vibration suppression capability.
Data Source
AI summary
In positioning control of a machine in which residual vibrations are caused due to a low mechanical rigidity, residual vibrations are suppressed within an allowable positioning error, and a positioning time period required for the positioning control is shortened.Based on information of operation conditions and residual vibrations, the amplitude of the residual vibrations of the machine is predicted before execution of positioning, and based on a result of the prediction, a first servo controller (11) which performs positioning control in which suppression of residual vibrations of the machine is not considered or a second servo controller (12) in which suppression of residual vibrations of the machine is considered is automatically selectively used.