Encoder and control apparatus for motor

Abstract

In a control apparatus, a 'characteristic value calculation' block calculates a characteristic value (such as amplitude value, offset value, or waveform distortion for each phase of two-phase sinusoidal signals optically input from an encoder, or phase difference between the two phase signals) for each of the two-phase sinusoidal signals, and an 'alarm detection' block checks the presence or absence of an excursion outside a predetermined allowable range and, if such an excursion is detected, produces an alarm indication or the like. Each time the 'present characteristic value' is input, a 'characteristic value comparison' block compares it with 'previous characteristic values', and analyzes the result of the comparison. That is, the difference between the present value and each previous data is calculated, and the largest amount of variation (with plus or minus sign) is obtained; if this amount is larger than a predetermined value, a signal indicating an 'imminent failure' is output. In an alternative method, the present value is compared with a characteristic value calculated from an encoder reference signal. Further, the characteristic value monitoring and comparison may be performed within the encoder. In this way, data useful for the prediction of encoder failure, etc. is provided.

Description

technical field [0001] The present invention relates to an encoder installed on a motor or a device driven by a motor to detect position information or speed information, accept and analyze the analog encoder signal generated in the encoder, and control the above-mentioned Control devices for electric motors, in particular related to the technique of providing a valuable information for the failure prediction of the same encoder. Background technique [0002] In an encoder mounted on a motor or a machine driven by a motor to detect position information or speed information, abnormalities may occur due to various internal factors, external factors, or changes over time. In order to deal with such an abnormal situation, in the past, such a method was adopted: Figure 1a or Figure 1b The configuration shown in the block diagram of FIG. 10 outputs alarm information and notifies the operator, for example, by means of an alarm display on a display of the control device or an ala...

AI Technical Summary

Problems solved by technology

[0007] However, with these previous methods, it is difficult to predict failures prior to notification of warning information

In addition, according to experience, when the above-mentioned allowable range (lower limit Vth1 to upper limit Vth2) is set relatively narrow, alarms may occur intermittently, and the cause may not be identified.

For such problems, no literature has been found that records effective solutions

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