Electrical, Computer, and Systems Engineering Department

ECSE 4962 Control System Design, Spring 2004


Course Information

Course Outline

Calendar

 

Meeting Slides and Other Useful Information

 

Project Overview

Design Project Resources

Announcements:

q       Progress report due date and presentation date postponed by 1 week to March 24.

q       Notes on friction ID

     Some of the teams have noticed that their friction ID results are much improved if they hit the system with a torque pulse to break friction before allowing the system to reach steady state velocity:
   (1) Give the system a large pulse of torque in the direction of rotation to break friction.  The duration should be somewhere around 0.25 seconds.
   (2) While the system is still spinning, command your desired constant torque value.
   (3) Allow the velocity to reach steady state.  Filter, average, etc. to get a good velocity data point.

q       Amplifier gain:   The nominal amplifier gain is 0.1 Amps/volt.

If you consider that the torque generated by the motor is proportional to the current through the motor (this gain is the motor torque constant from the data sheet) you can now calculate the relationship between D/A voltage and motor torque (don't forget about the gears between the motor and the output shaft).

q       Important notes about running experiments in the lab (from Ben Potsaid)

The hardware that we have in the lab is real and the typical application is industrial rather than educational.  As such, there are no built-in safety features to protect your experiment and the pieces will not magically fit together nicely like the problems in the back of a textbook.  Whenever running an experiment, I suggest that you proceed cautiously,
think things through thoroughly, and take the time to do some planning before powering up the experiment.

Here are a few things I do before running a new experiment or code:

  1. Run new code on the tilt joint only.  Disconnect the pan cable from the electronics box.  The tilt joint can spin indefinitely without wrapping wires, so if the experiment goes unstable, nothing will get damaged.

  2.  In the Simulink model, you can define how long your code will run. For a new controller, set the program end time to a small value, such as 1 second.  At worst, your controller will only be unstable for 1 second before shutting off the motors.

  3. Check the directionality of each component before running any closed loop code.  First, modify the Simulink diagram so that a constant source of value zero feeds the D/A converter.  This will ensure that the motor is not powered up during the experiment.  Run the code and turn the shaft by hand.  Take note of which direction is positive and which direction is negative.  Next, remove the belt from the drive motor (loosen the tension in the belt first).  Modify the code to give a small
positive value to the D/A converter.  Run the code and take note of the direction of motor spin.  Refer to your understanding of feedback control to determine if you need to reverse the sign of the encoder or motor.

  4. Use very small feedback gains at first.  Increase the gains slowly as you build confidence in your controller.

   BE CAREFUL!!!

q       Experiment assignment

Team 1 gets Team 2 setup from last year

Team 2 gets Team 5 setup from last year

Team 3 gets Team 6 setup from last year

Team 4 gets Team 3 setup from last year

Team 5 gets Team 4 setup from last year

Team 6 gets Team 1 setup from last year

Team 7 gets Team 7 setup from last year

q       You should download MATLAB 6.5 to your laptop from       http://www.rpi.edu/dept/arc/web/licenses/matlab_license.html

Make sure you select at least MATLAB, Simulink, xPC Target, Real time workshop, and control toolbox.


Mailing Address:

John T. Wen
Office: CII 8213
Voice: (518)-276-8744
Fax: (518)-276-4897
Email: wen@cat.rpi.edu