How Does The Servo Motor Calculate The Distance Of Workpiece Moving?

- Feb 26, 2019-

How does the servo motor calculate the distance of workpiece moving?


In the form of the following figure, the servo motor drives the screw to rotate and move the workpiece. We know that servo motors have precise positioning and quick response advantages compared to ordinary motors,and are used for higher position place. Then how is it positioned, the entire servo drive system is a closed-loop feedback system, the servo motor has an encoder at the end, which will always transmit the data of the motor rotation to the servo drive, to ensure that the motor reaches the specified position.


The example above shows how to calculate the distance the workpiece travels. The servo motor is driven in the form of pulse + direction. For the convenience of calculation, after the driver is equipped with the electronic gear ratio, for example,the amount of workpiece movement is 1 um / pulse. Send a pulse to move the workpiece 1um, send 1000 is a distance of 1mm. The speed at which the workpiece moves is determined by the frequency of the pulse, assuming the pulse frequency is 500pulse/s, then the workpiece moving speed is 0.5mm/s. Knowing the speed, the distance that the servo motor drives the workpiece to travel in a specific time is calculated by multiplying the speed by the time.It should be noted here that the command to send a pulse generally has acceleration and deceleration, and the whole movement process is not uniform. It is not accurate to calculate the distance with time unless the acceleration/deceleration function is removed.

In fact, the position of the servo motor does not need to be calculated. The encoder is constantly measuring the rotation of the motor. We only need to collect the encoded data to know the position of the workpiece, or check the number of pulses at the controller as well.

Very simple, any servo drive has parameters to monitor the actual position of the motor. TakeShenzhen ECON Technology  the servo drive as an example. DP-CPO is the command pulse low 5 bits;DP-CPO. is the command pulse high 5 bits.

(The number of digits displayed on the digital tube is 5). If the initial position is 0, after a position, the DP-CPO is 2000, and the DP-CPO. is 0010. The actual position is 102000, if you set  the electronic gear ratio is 10/1 for the ac servo controller, that is, one pulse of 1000 pulses. The conversion is that the motor has gone 102000/1000=102 laps.

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