0.2 Control lab setup: using labview to control ecp plants

Using labview to control ecp plants

This document provides a brief overview of how to use the National Instruments LabVIEW Virtual Instrument (VI)developed by The University of Texas at Austin Aerospace Engineering Controls Laboratory to perform control systemexperiments with the Educational Control Products (ECP) Model 210 Rectilinear and Model 205 Torsional plants.

Fpga personality vis:

Fpga vi specifics for each plant

The provided FPGA VIs contain the code for the reconfigurable I/O board which sends and receives signals, suchas motor drive voltage and quadrature encoder channels, from the plants. Furthermore, the FPGA code incorporates safety features,such as motor overvoltage protection, to help prevent damage to the plants.

The FPGA VIs for the two plants are similar but differ in the following ways:

• For the Model 205 Torsional Plant, the A and B channels for encoder 3 have been switched due to the fact that the physicalorientation of encoder 3 is opposite that of encoders 1 and 2.
• The Model 205 Torsional Plant does not have limit switches, but to prevent damage to the torsion rods, the VI will write zerovoltage to the drive motor in the event that the displacement between disks 1 and 2 or disks 2 and 3 exceeds 3000 counts (67.5degrees). The voltage will remain at zero until the error is cleared.
  • File Name of LabVIEW 8.0 Project: ECP 205 Project.lvproj (within LabVIEW 8.0 Starting Point.zip below)
  • File Name of LabVIEW 7.1 Project: ECP 205.lep (within LabVIEW 7.1 Starting Point.zip below)
• The Model 210 Rectilinear Plant has limit switches to prevent damage due to excessive travel of the mass carriages. If a limitswitch is engaged, the VI returns a value of true to an error indicator and writes zero voltage to the drive motor until theerror is cleared.
  • File Name of LabVIEW 8.0 Project: ECP 210 Project.lvproj (within LabVIEW 8.0 Starting Point.zip below)
  • File Name of LabVIEW 7.1 Project: ECP 210.lep (within LabVIEW 7.1 Starting Point.zip below)

The FPGA VI for both plants incorporates drive motor overvoltage protection. If an overvoltage condition isdetected, zero voltage will be written to the motor until the error is cleared.

The portion of the code which interprets encoder signals has been written such that for the 210 plant, adisplacement to the right results in a positive measurement. For the 205 plant, a positive measurement results from acounterclockwise disk displacement. When using the ECP pendulum accessory, a counterclockwise rotation will result in a positiveencoder measurement (encoder 4).