how to control dc servo that match to torque profile of the motor ?

[shawn chew]

Hi,

I just start using Labview no long and What i doing is using the Labview 8.2 program to control the position of the dc servo motor.  My program now works with input the position/distance (cm) then convert to degree and compare with the feedback of the encoder of the servo motor as a closed loop. Then go through the PID controller to control the motor.

But what i found when there is input the motor will draw as much current to accelerate to achieve the max velocity for certain voltage (depends on limit set in my program) and this is not good for the servo.  So i wonder can i create a velocity profile from motor torque profile, to make the motor follow the velocity profile that below the max limit of the motor to limit the motor acceleration ?

If can, How to program it ?

Thank you

[Lee.P]

Hi Shawn,

If you want to limit the motor acceleration, is it the same as modifying your PID constant values?? This will determine how fast to achieve the set point.

I am not sure about creating a velocity profile from motor torque profile. However, if your motor have encoder, you can read from the encoder to find the rate of change of motor position. This also depends on what hardware you are using.

Regards

Lee

Applications Enginner | NI ASEAN

[shawn chew]

Hi Lee,

Thanks for your reply.

According to what i know, It is a bit different from the PID. My project is to comes out with a program that can generate a smooth profile according to the distance input for different load. The system i using now is a DC servo motor that driving the cable with vertical load. I will get the max acceleration of the motor. Then i will comes out with a smoother profile (after modify from the original) that generated by equations and write into spreadsheet ( consist of time and distance move ). Then the motion of the motor will run by reading the value of each time in the spreadsheet. Is it able to program in such way ?

Besides that, i still on the way to try to implement what i mentioned above into the Labview program.

Thanks

Regards,

Shawn