Numerical Control Device Frequency Characteristic Calculation
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Solution Overview
Problem
Existing numerical control devices face challenges in achieving high measurement precision in the high-frequency region due to the limitations of using white noise signals, which result in waveform changes and difficulties in accurately evaluating frequency characteristics beyond the Nyquist frequency.
Innovation Solution
A numerical control device that generates sinusoidal signals with a predetermined initial phase and shifts the phase by a certain amount, allowing multiple inputs to the control loop to improve measurement precision by securing multiple sampling points per period, thereby enabling precise frequency characteristic calculation in the high-frequency region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If white noise signal is used to excite the speed loop, then measurement time is reduced, but measurement precision in high frequency region deteriorates
Solution Approach 1:
The patent uses periodic sinusoidal signals instead of random white noise to excite the control loop. By applying sinusoidal signals at multiple discrete frequencies sequentially, the system achieves both efficient measurement (avoiding the need for gradual frequency sweeping) and high precision (through controlled periodic excitation that allows accurate spectral analysis)
Solution Approach 2:
The patent changes the frequency parameter of the sinusoidal excitation signal across multiple measurement cycles. By systematically varying the frequency parameter while maintaining sinusoidal waveform characteristics, the system can efficiently measure the entire frequency range while preserving measurement precision through the regular structure of sinusoidal signals
2Measurement precision
If sinusoidal signal frequency is gradually increased, then measurement precision is improved, but measurement time increases
Solution Approach 1:
The patent performs preliminary selection of discrete frequency points before measurement. By pre-determining the specific frequencies to be tested and preparing sinusoidal signals at these frequencies in advance, the system eliminates the need for gradual frequency sweeping while maintaining measurement precision through targeted excitation at critical frequency points
3Ease of operation
If white noise is used for excitation, then frequency characteristic measurement is simplified, but waveform changes make high frequency measurement difficult
Solution Approach 1:
The patent uses multiple copies of sinusoidal signals at different frequencies instead of a single white noise signal. By generating and applying multiple sinusoidal waveforms with known, stable frequency characteristics, the system maintains ease of measurement while avoiding the waveform instability problems of white noise through the use of replicated, controlled sinusoidal excitations
Data Source
AI summary
A numerical control device wherein a sinusoidal signal generated by a sine wave generation part is input by a control loop excitation part to a control loop of the control object, the input signal input to the control loop and the output signal from the control object are sampled by the data acquisition part periodically, and the sampling data is used by the frequency characteristic calculation part to calculate the frequency characteristic of the control loop to control the control object, wherein the frequency characteristic calculation part uses data obtained by inputting a sinusoidal signal obtained by shifting an initial phase of the sinusoidal signal by a phase shift part provided at a sine wave generation part by exactly a certain amount to the control loop a plurality of times to calculate the frequency characteristic of the control loop to thereby improve the measurement precision regardless of the sampling frequency.