Servo Driver Resonance Gain Detection
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Solution Overview
Problem
Existing servo driver techniques fail to prevent mechanical resonance by only detecting changes in resonance frequency and can disrupt the control of servo motors when adding a sine wave disturbance, leading to potential mechanical resonance issues and inaccurate state notifications.
Innovation Solution
A servo driver system that calculates and identifies the gain of the resonance peak from frequency responses within a specific range, comparing it to a threshold to notify users of state changes before mechanical resonance occurs, without affecting the servo motor's behavior or relying on the direction of resonance frequency changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sine wave disturbance value is added to the velocity command to detect resonance frequency, then the resonance frequency can be detected, but the machine cannot be controlled as instructed by a host device
Solution Approach 1:
The patent segments the control process into two distinct modes: a normal control mode for executing host device commands, and a detection mode for measuring resonance frequency. The switching between these modes allows the system to perform accurate resonance detection without compromising normal control operations.
Solution Approach 2:
The patent performs resonance frequency detection in advance during a preliminary detection phase before normal control operations begin. By detecting the resonance frequency beforehand and storing it for later use in notch filter settings, the system avoids the need to continuously disturb the system during normal operation.
2Reliability
If the notch filter center frequency is adjusted to match resonance frequency, then mechanical resonance can be suppressed, but the resonance frequency changes over time due to machine changes
Solution Approach 1:
The patent implements a dynamic resonance detection mechanism that periodically remeasures the resonance frequency during system operation. Instead of using a fixed resonance frequency value, the system continuously adapts by detecting changes in resonance frequency and updating the notch filter parameters accordingly, ensuring sustained effectiveness despite machine changes.
Solution Approach 2:
The patent employs feedback by monitoring the gain of the resonance peak and comparing it against a threshold. When the gain exceeds the threshold, indicating a change in resonance characteristics, the system triggers a remeasurement of the resonance frequency and adjusts the notch filter settings accordingly, creating a closed-loop control system.
3Reliability
If the gain of resonance peak becomes equal to or greater than 0 dB, then mechanical resonance occurs, but detection should be performed before this point
Solution Approach 1:
The patent performs preliminary detection by monitoring the gain of the resonance peak and comparing it against a threshold value less than 0 dB. This allows the system to issue maintenance notifications before the gain reaches 0 dB and actual mechanical resonance occurs, enabling preventive maintenance while maintaining system reliability.
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 early notification of mechanical system deterioration before mechanical resonance occurs, preventing vibrations and maintaining accurate servo motor control without disrupting the system's operation.
Implementation Method 1
calculation means configured to collect, on a time-series basis, input data and output data for use in calculation of a frequency response of the servo control means
Implementation Method 2
Mechanical resonance occurs after the gain of the resonance peak (hereinafter, resonance peak gain) becomes equal to or greater than 0 dB
Data Source
AI summary
Provided is a technology of enabling notification, to a user, that the state of a machine system has changed prior to occurrence of machine resonance, irrespective of the direction of a resonance frequency change. This servo driver is provided with: a servo control means for controlling a servo motor in accordance with a time-sequentially inputted command; a calculation means for time-sequentially collecting input data and output data for use in calculation of the frequency response of the servo control means while the servo control means is performing control, in accordance with a command for driving the servo motor itself, based on the command, and calculating a frequency response of the servo control means within a frequency range including a resonance peak, on the basis of the collected data; a specification means for specifying the gain of the resonance peak from the calculated frequency response; and an information output means for comparing the specified gain with a threshold lower than 0 dB, and outputting, when the gain is equal to or greater than the threshold, information for notifying, to a user, that the state of a machine system such as the servo motor has changed.