Anti-jamming principle of rotary encoder, encoder disturbance is how to judge?

by:HENGXIANG     2020-11-05
Rotary encoder is a kind of sophisticated electronic components, the use of the environmental requirement for anti-interference, today with everyone know about the rotary encoder anti-interference system design principle, how to determine whether to encoder failure itself? Or interference. Rotary encoder anti-interference system design principle of rotary encoder is rotate displacement sensor, it is rotated into a series of digital pulse signal can be used to control the angular displacement. So how to interfere with the motion control system of rotary encoder anti-interference design? Signal transmission channel: shielded twisted-pair cable transmission, the signal will be subject to an electric field, magnetic field and the impedance of the interference factors in the process of transmission. Compared with coaxial cable, although the band is poor, but the impedance, high common mode noise, make each a small part of the electromagnetic interference can be offset each other. Photoelectric coupling isolation measures in long distance transmission, photoelectric coupler can cut off the circuit connection between control system and the input channel and output channel and servo driver input and output channels. Photoelectric coupling main advantage is can effectively restrain peak pulse interference and noise, thus greatly improve the signal to noise ratio ( SNR) 。 Although the noise voltage is larger, but less energy, only weak current, and light-emitting diodes (leds) input part of the work in the current state of photoelectric coupler, generally for 10 - current flow 15 ma, so even if can't provide enough current is inhibited, so the interference is very big. Power system anti-interference design: the implementation of power module, for example, will implement motor drive power and control power, to prevent interference between devices. Using isolation transformer, considering the mutual inductance coupling of high frequency noise is not dependent on early stage through transformer secondary coil, but in the auxiliary parasitic capacitance coupling between primary and secondary, isolation transformer isolation and shielding layer, therefore, to reduce the capacitance, in order to improve the ability to resist common mode interference. Noise filter can effectively restrain the interference of other ac servo drive. In many cases is rotary encoder is not bad, but the cause of interference, cause the wave pattern is not good, is not allowed to count. Rotary encoder are precision components, largely because of interference is more serious around the encoder, such as: whether there is a large motor, electric welding machine is frequent start causing interference, whether the same pipeline transmission and power line, etc. It's also important to choose what kind of output against interference, the general output with reverse signal anti-jamming is better, namely A + to A - ,B+~B- ,Z+~Z- 8, whose character is combined with the power wire, rather than 5 thread ( A total of zero) 。 With reverse signal in the cable transmission is symmetrical, interference is small, can also add judgment in the receiving equipment ( Such as accept equipment signals using A, B & 90 deg; Phase difference, read level 10, 11, 00, 01, four kinds of condition, the meter is an effective pulse, this scheme can effectively improve the system anti-interference performance ( Count accurate) ) 。 How to determine whether to encoder failure itself? 1, eliminate ( Move, close, isolation) Interference sources; 2, determine whether to mechanical clearance accumulated error; 3, determine whether to control system and the encoder interface circuit mismatch ( The encoder selection error) ; After 1, 2, 3 methods try breakdown phenomenon, can preliminary judgment, if did not rule out further analysis. Determine whether to encoder failure itself simple method is functional. Method the specific method is: use the encoder to replace a same model, if the same failure phenomenon, is the basic rule out the encoder failure problem, because the two encoders and defective small probability events may be small, we can see as 0. If, in a same model encoder immediately ruled out fault phenomenon, is the basic judgement is encoder failure. Shanghai electronic products specializing in the production of rotary encoder for 27 years, rotary encoder with multiple-choice, the old factory, can according to customer needs size, accuracy, such as pulse to customize products. One of electronic research and development production of rotary encoder for magnetoelectric encoder, price higher than that of photoelectric encoder, magnetoelectric encoder performance not easily affected by dust and condensation; Its simple and compact structure, non-contact, long life, high and low temperature resistance, resistance to vibration, fast response speed and lower cost. Looking for a rotary encoder manufacturer is looking for electronic.
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