Servo Control Apparatus for Natural Vibration Suppression
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Solution Overview
Problem
Existing control apparatuses struggle to accurately detect natural frequencies in controlled objects driven by electric motors, leading to unstable operation due to mistaken detection of vibrations and resonance, especially in machines with varying natural frequencies and limited processing capacity.
Innovation Solution
A control apparatus comprising a frequency analysis unit, detection unit, and filter characteristic setting unit that samples control signals, applies discrete Fourier transforms, and adjusts band rejection filter coefficients based on detected natural frequencies to accurately identify and attenuate natural vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If continuous frequency detection is performed to track changing natural frequencies, then the control system can adapt to frequency variations, but the processing time and computational load increase excessively
Solution Approach 1:
The patent implements periodic frequency detection at specific intervals during machining operations rather than continuous detection. The natural frequency is detected at predetermined timing points (e.g., when machining parameters change or at regular intervals), allowing the system to track frequency variations while minimizing processing time and computational load.
2Measurement precision
If frequency detection is performed continuously to track natural frequency changes, then the control system can maintain accuracy, but the computational resources and processing capacity are excessively consumed
Solution Approach 1:
The patent applies partial frequency detection by selecting specific timing points for detection rather than continuous monitoring. Frequency detection is performed at critical moments when natural frequency changes are most likely to occur (e.g., when machining parameters change, when tool engagement changes, or at predetermined intervals), providing sufficient accuracy while reducing computational resource consumption.
3Speed
If the control system responds quickly to frequency changes, then control precision is maintained, but the response time may be insufficient to detect accurate natural frequency
Solution Approach 1:
The patent performs frequency detection in advance at predetermined timing points before critical machining operations or parameter changes. By detecting natural frequency proactively at these intervals, the system prepares the control parameters ahead of time, ensuring both quick response and accurate detection without the need for continuous monitoring.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables precise detection and reduction of natural vibrations, stabilizing the controlled object by distinguishing between natural and non-natural vibrations, and adapting filter settings to maintain control precision and stability.
Implementation Method 1
a frequency analysis unit analyzing a frequency included in a control signal of the torque command
Implementation Method 2
a band rejection filter stripping the torque command of a natural frequency component
Implementation Method 3
When its rigidity or attenuation characteristic is low etc., sometimes the controlled object will resonate at the natural frequency and vibration having a large amplitude will occur
Data Source
Figure 1A
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Figure 2
AI summary
A control apparatus comprising a control unit outputting a control signal controlling a servo motor and suppressing natural vibration of a controlled object including a motor and a machine driven by the motor while controlling the controlled object, comprising a frequency analysis unit analyzing a frequency component included in a torque command, an analysis control unit controlling the start or stopping of the frequency analysis unit, a detection unit detecting a natural frequency of the controlled object from an analysis result of the frequency analysis unit, a band rejection filter receiving as input the torque command, stripping the command of the natural frequency component, and outputting the resultant command to the motor through a current control unit and servo amplifier, and a filter characteristic setting unit setting the frequency to be stripped at the filter based on the natural frequency detected by the detection unit.