HIL Position Control Example

This example demonstrates how to do proportional control using the QUARC HIL command set. It is designed to control Quanser's QUBE-SERVO2-USB experiment. The position of the motor is read from encoder channel 0. Analog output channel 0 is used to drive the motor.

System Requirements

This example requires hardware supported by the HIL command set, such as the QUBE-SERVO2-USB device. Furthermore, the card must support task-based reading of an encoder channel and immediate writes to an analog output channel.

Configuring the example

To set up the example for a different data acquisition card, edit the M-file and change the board_type to the type of board being used. If you have more than one of these data acquisition cards in your machine, then also change the board_identifier variable to refer to desire board. Board identifiers are typically equal to the board number, with the first board being board '0', the next board being board '1', etc.

Running the example

Simply type the name of the example, hil_position_control_example, at the Matlab command prompt to run the example. It will run until the Esc key is pressed and then plot the results.

Warning

Do NOT press Ctrl+C to stop the script or the example will not stop the motor and will not shut down the hardware correctly! Use the quanser.hardware.hil.close_all command in order to shut down the hardware if you have pressed Ctrl+C.

The QUBE-SERVO2-USB motor will move back and forth between +/-45 degrees. The controller is running at 1 kHz.

The controller will run for 10 seconds and then stop. The example will zero the analog outputs to stop the motor. It then plots the command signal versus the measured motor position, as shown below.

Command signal versus measured position plot

Building code from the example

To build real-time code from the example for the QUARC Win64 target, execute the following command in the MATLAB Command Window:

qc_build_script('hil_position_control_example', 'win64');

The command may also be entered in this form:

qc_build_script('hil_position_control_example.rt-win64');

The qc_build_script command generates a build script called 'hil_position_control_example_build.m' and a main C file called 'hil_position_control_example_main.c'. It then invokes the build script to generate C code for the MATLAB script and to compile and link it into a QUARC executable called 'hil_position_control_example.rt-win64'. Running qc_build_script again will not overwrite the generated files, so they may be modified and the changes will be incorporated when qc_build_script is run again.

Running the generated executable

Before running the generated executable, open a QUARC Console so that the output of the executable may be seen. The QUARC Console need only be opened once. Use the command:

qc_script_console('hil_position_control_example.rt-win64', 'all');

The QUARC Console shows the standard output from any QUARC executable that is run on the target (since the 'all' option was specified).

To run the generated executable, type the following command in the MATLAB Command Window:

qc_run_script('hil_position_control_example.rt-win64');

The output from the executable will be seen in the QUARC Console:

QUARC Console output

Building code for a different target

To build real-time code from the example for the QUARC Linux Pi 3 target, execute the following command in the MATLAB Command Window:

qc_build_script('hil_position_control_example', 'linux_pi_3', 'update');

The command may also be entered in this form:

qc_build_script('hil_position_control_example.rt-linux_pi_3', 'update');

The 'update' option causes the qc_build_script command to update the target type in the build script without rewriting the rest of the script. Hence, even if the script has been modified, the changes will be preserved. Only the target type will be changed. The command will then generate the C code for the MATLAB script and compile and link it for the new target type to produce the executable 'hil_position_control_example.rt-linux_pi_3'.

Running the generated executable on the new target

Before running the generated executable, open a QUARC Console so that the output of the executable may be seen. The QUARC Console for this new target need only be opened once. Use the command:

qc_script_console('hil_position_control_example.rt-linux_pi_3', 'all');

The QUARC Console shows the standard output from any QUARC executable that is run on the target (since the 'all' option was specified). Note that even though the QUARC Console is running on the host PC, it will be showing the standard output from QUARC executables run on the QUARC Linux Pi 3 target!

To run the generated executable, type the following command in the MATLAB Command Window:

qc_run_script('hil_position_control_example.rt-linux_pi_3');

The output from the executable will be seen in the QUARC Console.