I am driving dc motor with drv8848. I send pwm pulse to the drv8848 and then ı read encoder value. My pwm frequency is 500 Hz. So here is my problem, pulse count is same but encoder value is different. I don't expect to be same. But difference is very big. For example one time I send same pulse count, encoder value is 4 um but in other same pulse count encoder value is 15 um. So can you help me about this problem ?
thanks
Electrical – Dc Motor Position Control
controldc motorencoder
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I saw that rWheel doest take overflow into account. Does millis() take overflow into account ? PID seems ok. I see you have anti-wind up implemented. Did you try PI only ?
In looking through the technical information for the DFs60 encoder range it appears that the programming cable will be an essential part of gaining access to the encoder for the user programmability of the output lines/revolution count.
In looking at the normal pinning for the encoder connector it can be seen that the normal encoder signals of +A, -A, +B, -B, +Z, -Z, GND, SUPPLY, and SHIELD are documented.
The special order programming cable is clearly using the signal pinning of the encoder in a special way to adapt to a serial port connectivity via the D-SUB 9 pin connector off the adapter. The nature of the special usage of the signal lines for performing this programming is not documented on the encoder data sheets and so it if generally not feasible to try to work around this on your own.
Your best bet at success with this is to contact the manufacturer (SICK STEGMANN) in Germany and explain your issues to them. Indicate that you are working in an educational institution setting and it may turn out that they may support you in one of two ways. One option is that they may donate a programming cable to your educational facility. The other option, which is much more likely, is that they may refer you to a dealer, distributor or sales/support office in your area where you could take the encoder and get it programmed into the format useful to your application.
Best Answer
There is no relation between PWM pulses and encoder feedback pulses. When you send PWM pulses, you supply the motor with voltage which is V = Vdc * DutyCyleRatio. The encoder measures the position of rotor. Where did you got the idea that PWM pulses == encoder pulses?