Abstract:
The present invention aims to easily suppress noise components of aliases when measuring a velocity based on an output from an encoder. The invention comprises a step for converting in which two-phase signals indicating the movement of a spinning body, etc., are converted to a ternary pulse train signal having a positive or a negative or a zero value corresponding to the phases of the two-phase signals, a step for low pass filtering in which a low frequency component of the pulse train signal is obtained by arithmetically processing the pulse train signal and filter coefficients, and a step for output-sampling in which the signal obtained by the step for low pass filtering is sampled at a predetermined sampling period. In the step for low pass filtering, a convolution (operation for convolution) between the pulse train signal obtained by sampling the pulse train signal at a predetermined period and the filter coefficients is carried out. Sampling the pulse train signal is synchronized with and has the same phase as reading the filter coefficients for the convolution. The sampled signal by the step for output-sampling is output as a velocity signal corresponding to the velocity determined by the two-phase signal.
Abstract:
To suppress a decline in the control accuracy of an applied voltage associated with an increase in quantum noise, and to increase the control accuracy of a motor speed. When generating a driving voltage signal supplied to a motor from a driving command signal, a motor-driving voltage control device reduces the gradation level and performs noise-shaping modulation before performing PWM modulation. Reducing the gradation level allows the degree of gradation of the driving voltage signal to be within the resolution range of the PWM modulation, and thus PWM modulation can be performed even when the driving voltage signal has a high frequency. Noise-shaping modulation reduces the level of quantum noise near the low frequency range by causing the quantum noise due to digitization, included in the driving voltage signal, to be biased toward the high frequency range side. Of modulation signals with the reduced-gradation level, the components near the high frequency band are cut, while the components near the low frequency range are used to suppress quantum noise and control the driving voltage applied to the motor with a high accuracy.
Abstract:
The structure for detecting tooth-skipping of the speed reducer of the rotary driver is reduced in weight and size. In the rotary driver the occurrence of tooth-skipping is detected based on the difference in outputs from the encoders located at the input side (the side of the motor) and at the output side (the side of the load), which is opposite the input side in relation to the speed reducer. The rotary driver comprises a motor, a speed reducer located between the motor and a load to reduce the rotary speed of a rotary shaft at the side of the motor, to thereby transmit the reduced rotary speed to a rotary shaft at the side of the load, a first encoder for detecting a rotation of the rotary shaft at the side of the motor, a second encoder for detecting a rotation of the rotary shaft at the side of the load, a section for detecting any difference between a first detected value that is obtained by dividing an output of the first encoder by a rate for reducing the speed by the speed reducer and a second detected value that is obtained from an output of the second encoder, and a section for detecting tooth-skipping that detects tooth-skipping of the speed reducer based on the difference.