Servo Motor Controller Stiffness Measurement via Resonance Detection
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Solution Overview
Problem
Existing servo motor controllers lack comprehensive inspection technologies for non-destructive and non-disassembly maintenance, and fail to effectively manage secular changes and individual differences in machine tool stiffness over time.
Innovation Solution
A servo motor controller with a speed command generating unit, speed detecting unit, torque command generating unit, sine wave generating unit, frequency response calculating unit, resonance frequency detecting unit, and a filter that adjusts based on measured resonance frequency to dynamically assess and stabilize machine tool stiffness without disassembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual filter adjustment is performed by engineer, then adjustment policy and capacity affect results, but variation in adjustment results is large
Solution Approach 1:
The system performs automatic filter adjustment without engineer intervention. The resonance frequency detecting unit automatically detects resonance frequencies, and the adjusting unit automatically adjusts filter parameters based on detected frequencies, eliminating manual adjustment and its associated variations.
Solution Approach 2:
The patent replaces manual mechanical adjustment with an automatic control system. The adjusting unit uses control algorithms to automatically modify filter parameters based on detected resonance frequencies, substituting human operation with automated electronic control.
2Measurement precision
If automatic filter adjustment is implemented, then stiffness measurement variation is reduced, but long-term secular change and individual difference cannot be coped with
Solution Approach 1:
The system performs continuous or periodic resonance frequency detection and filter adjustment throughout the machine tool's operation. This continuous monitoring enables detection of long-term secular changes in stiffness and individual differences between machines, maintaining reliability over extended periods.
Solution Approach 2:
The system establishes a feedback loop where resonance frequency detection results are fed back to the adjusting unit, which continuously modifies filter parameters. This feedback mechanism enables the system to adapt to long-term changes in machine tool stiffness and maintain optimal performance.
3Object-generated harmful factors
If multiple band elimination filters are used for resonance suppression, then resonance can be suppressed, but filter width must be widened when center frequencies are adjacent
Solution Approach 1:
The adjusting unit automatically determines optimal filter parameters including widths and center frequencies based on detected resonance frequencies. This self-service capability eliminates the need for manual filter width widening and complex parameter management, allowing multiple filters to work effectively without increasing device complexity.
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 non-destructive and non-disassembly maintenance inspection prediction, effectively managing stiffness variations and secular changes, improving quality management and manufacturing processes by dynamically measuring and adjusting resonance frequencies to maintain optimal mechanical stiffness.
Implementation Method 1
a sine wave generating unit (4) for generating a sinusoidal disturbance value
Implementation Method 2
a frequency response calculating unit (5) for adding the sinusoidal disturbance value generated by the sine wave generating unit (4) to the speed command value, thereby calculating a frequency response
Implementation Method 3
a resonance frequency detecting unit (6) for detecting a resonance frequency which is a frequency at which a gain of the calculated frequency response is maximized
Implementation Method 4
at least one filter for attenuating a specific frequency band component included in the torque command value
Data Source
AI summary
A servo motor controller includes a speed command generating unit for generating a speed command value of the servo motor, a speed detecting unit that detects a speed of the servo motor, a torque command generating unit for generating a torque command value, a sine wave generating unit for generating a sinusoidal disturbance value, a frequency response calculating unit for calculating a frequency response when the sinusoidal disturbance value has been input to a speed control loop, a resonance frequency detecting unit for detecting a resonance frequency at which a gain is maximized, a resonance frequency storing unit for storing the resonance frequency, at least one filter for attenuating a specific frequency band component included in the torque command value, and a resonance frequency comparing unit for measuring stiffness of a machine tool based on the resonance frequency and adjusts the filter with respect to the resonance frequency.