Quanser Inverted Pendulum Balance Control Demonstration

This demonstration includes a sample experiment using the Quanser Inverted Pendulum Trainer, and demonstrates the self balancing of the control system in a step-by-step manner. This experiment is a part of a larger set of experiments demonstrating the various educational theories that can be observed and taught using the Quanser Inverted Pendulum trainer.

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Quanser Inverted Pendulum Balance Control Model

Please note that the VI required to run this experiment is obtained with the purchase of the Quanser Inverted Pendulum.  This experiment is provided as a demonstration of the step by step instructions

Procedure

Before you start, make sure that you are running the correct VI.  The VI for this particular example is called 08-QNET_DCMCT_Swing_Up_Control.vi.

Double click the 08-QNET_DCMCT_Swing_Up_Control.vi and let LabVIEW load all the relevant subVIs into memory.  After the VI is completely finished loading all of the subVIs into memory, you will see the following screen.

Figure 1.  DC Rotational Pendulum Simple Modeling Control Front Panel

Balance Control

1. Activate the control by clicking on the Start Control button.
2. In the Signal Generator section set:
3. • Signal Type = 'square wave'
   • Amplitude = 0.0 deg
   • Frequency = 0.10 Hz
   • Offset =  0.0 deg
4. In the Control Parameters section set:
5. • kp_theta = -2.65 V/rad
   • kp_alpha = 40.0 V/rad
   • kd_theta = -1.29 V/(rad/s)
   • kd_alpha = 6.46 V/(rad/s)
   • mu = 375 m/s^2/J
   • Er = 20.0 mJ
   • Activate Swing-Up = OFF (de-pressed)
6. Click on Update Control in the Control Parameters section to ensure this controller is implemented.
7. Adjust the Angle/Energy (deg/mJ) scope scales to see between -200 and 200.
8. Manually rotate the pendulum in the upright position until the In Range? LED in the Control Indicators section turns bright green. Ensure the encoder cable does not interfere with the pendulum arm motion.
9. Observe what occurs to Offset in the Signal Generator section when the balance controller is activated.
10. Vary Offset and observe the Arm Angle (deg) response in the Angle/Energy (deg/mJ) scope. Do not set the Offset too high or the encoder cable will interfere with the pendulum arm motion.
11. As the pendulum is being balanced, examine the red Arm Angle (deg) and blue Pendulum Angle (deg) responses in the Angle/Energy (deg/mJ) scope.
12. In the Signal Generator section set:
13. • Signal Type = 'square wave'
    • Amplitude = 40.0 deg
    • Frequency = 0.10 Hz
    • Offset =  0.0 deg
14. Adjust the Angle/Energy (deg/mJ) scope scales to see between -100 and 100.
15. Observe the behavior of the system when a square wave command is given to the arm angle. Why does the arm initially move in the wrong direction?
16. Click on Stop Control to disable the balance controller.

As a quick module description, the table 1 below lists and describes the main elements composing the QNET-ROTPENT Swing-Up Control virtual instrument user interface. Every element is uniquely identified through an ID number as identified in Figure 1.

Table 1. Main Elements of the DCMCT Rotational Pendulum Simple Modeling Front Panel

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