Høgskolen i Buskerud: Fag SESM3400 Styring av mekatroniske systemer

Prosjektoppgave:

Turtallsregulering med LabVIEW og USB-6008

Hva oppgaven går ut på

I denne øvingen skal dere lage et turtallsreguleringssystem for en likestrømsmotor vha. LabVIEW og USB-6008. Dere skal bruke en innebygd PID-regulator i LabVIEW.

Utstyr

  • PC med LabVIEW
  • USB-6008. Kun merkede PC'er på C212/213 kan brukes (drivere er installert kun på disse).
  • DC-motor

Oppgaver

  1. Configure and test the I/O device in MAX. Also check that you can actually control the motor and measure the speed (you can do this in MAX).
     
  2. Control system implementation: Implement a speed control system for the motor according the following specifications. You can use ao_ai.vi as a template for your speed control program. You should check that you can actually control the motor and measure the speed with ao_ai.vi before you proceed with the programming.
    • Use the PID Advanced function on the Control/PID-palette with sampling time 0.05 sec. Set the Output Range input to the PID function to 5 V maximum and 0 V minimum. The setpoint and the speed measurement shall be in units krpm (kilo revolutions per minute). The tachometer gain can be assumed to be 0.2 krpm/V.
    • Include a measurement filter a time constant of 0.2 sec. You can use timeconstant_lowpass_filter.vi which is available in this LabVIEW Goldmine.
    • The speed setpoint and the speed measurement in krpm shall be plotted in the same chart.
    • The control signal in volts shall be plotted in a separate chart.
       
  3. Controller tuning: Tune a PI controller for the motor (including measurement filter). Is the stability of the control system ok after the tuning?
     
  4. Steady-state control error (with PI controller):
    1. What is the steady-state control error after a step change of the setpoint?
    2. What is the steady-state control error after a step change of the disturbance (load torque)?
       
  5. The importance of the measurement filter: Does the measurement filter make the control signal (from the PI controller) smoother, compared to not having a filter?
     
  6. Stability of the control system:
    1. What happens to the stability of the control system when the controller gain is increased to a large value?
    2. What happens to the stability of the control system when the integral time is decreased to a small value?
    3. What happens to the stability of the control system if you set the the PID controller in direct mode (negative controller gain)?
    4. What happens to the stability of the control system if the sampling time of the control system is increased?

Oppdatert 6.10.08 av Finn Haugen, lærer. E-postadresse: finn@techteach.no.