Due Date: September 23, 1999
Contents
1. 5 Remember To Turn Off Power To ECP Box When Finished Note You may want to save the setup of the ECP controller to your Y drive 6 Writing the Report Please include the items listed above Label each item and number each item including commentaries according to its section Can you give a brief explanation for the use of a frequency sweep on an unknown uncharacterized system 4 of 42. EE411 Lab 3 1 Objectives The primary objectives of this lab are e Familiarize student with the general setup of the ECP lab stations this will save time in the future e Familiarize the student with the correlating real world data with modeling and simulation 2 Getting Familiar with the General Setup of the ECP lab Station 2 1 Safety Familiarize yourself with section 2 3 Safety in the blue user s manual pages 34 36 2 2 The Setup for the Model 220 Servo Trainer Lab Station Motor Gear Drive System Start the ECP program by finding the ECP32 icon on the Start Programs menu on Win NT Desktop Turn on power to the ECP lab station Under Setup select the User Units to be counts Use the Setup menu to locate and select Algorithm When Algorithm is selected select the following Set control Algorithm to Type Continuous Time Control Algorithm PID Click on Setup Algorithm and set the constants Kp 0 05 Kd 0 0 Ki 0 0 Select feedback to be from Encoder 1 and click OK Select Implement Algorithm This will load the algorithm into the ECP work station Click OK to close window Select Trajectory from the Command menu Select a Step input as the reference input to the system Setup the Step Size to 4000 counts with a Dwell time of 1000 msec Number of repetitions is 1 It will be a closed loop step Click OK to close the window Click OK to exit Trajectory settings 1 of 4 EE411 Lab 3 2 3 Setting up the Plot Select Da
3. axOvershoot is the peak of the first overshoot compared to the setpoint This equation can be solved explicitly as a quadratic or iteratively using an m file or Mathcad or Excel The time necessary to complete one of the damped cycles is a This g is related to the natural frequency of the system by the following Knowing this you can calculate the transfer function for the total closed loop system and equate values to solve for Km and a 3 of 4 EE411 Lab 3 Include your work showing your calculation of the overall system transfer function with a proportional gain controller Kp Calculate Values for n K Km and a from your collected Data and include them in the report 4 Modeling the Lab in Matlab Build a model of the system in Matlab Simulink using the parameters you have calculated Run simulations of the model using the same step input and Kp parameters as in the lab Note this is a modification of the simulink model you built in Lab 2 Use matlab to perform a frequency sweep of your model using the same settings as the lab system Plot the frequency magnitude dB versus frequency linear and compare to your experimental results Compare the results from the physical system and comment on any similarities or differences and their reasons for both the step input and the frequency sweep Include in your report a copy of your model and the response of the model to a step and sine sweep
4. ke more sense OK now plot the magnitude in dB along the vertical axis and frequency along the x axis include this plot only Explain what you re seeing in terms of the system 2 7 Adjusting Parameters Use a step trajectory as originally setup but with a dwell time of 2000 msec Make the PID parameters Kp 2 and Kd 005 Run the step response and examine a plot of the commanded position and the encoder output Now adjust Ki to 5 and re run the step don t forget to re implement the algorithm Examine a plot of the commanded position and the encoder 1 output Can you explain the difference you see between the steady state values of the system for the controller with and without the Ki term 2 of 4 EE411 Lab 3 2 8 Experiment with Control Parameters Try adjusting the control parameters for Kp Ki and Kd and observe the response to the step input Include two plots with the reports and state the Kp Ki and Kd values with the graph Hint don t make the changes too huge or you ll exceed the system limits and will have to restart the controller There should be a visible change in the system output response though 3 Taking Data and Analysis Use your numbers measured in section 2 5 above to do the analysis The general form of the total closed loop system is Where is referred to as the damping factor From the plot has the following relationship al MaxOvershoot 100e The M
5. ta and Setup Data Acquisition from the menu Use the Add Item buttons to add items to the plot Choose the Commanded Position and Encoder Position 1 Set the sample period to 2 Servo cycles Click OK Under Plotting select Setup Plot Using the Add to Left Axis button select the Commanded Position and the Encoder 1 Position Click OK Use Axis Scaling to zoom in and out on given portions of the plot for more accurate data recording 2 4 Initializing the Lab Station Under Utility select Zero Position 2 5 Running the Control Choose Command Execute select Normal Data Sampling if not checked Run Plot the data using the Plotting menu Include this plot with your report Measure the height of the first overshoot compared to the requested step Calculate Percentage overshoot Measure the time duration between successive overshoots and record convert this value to frequency also Time between successive overshoots seconds equates to a frequency of Hz 2 6 Frequency Sweep Set the PID parameters for Kp 1 Kd 005 Set the trajectory for a sine sweep between 5 and 20 Hz over a 30 second timespan with an amplitude of 50 counts This should be a closed loop linear sweep Plot the encoder I data with time along the horizontal axis and amplitude along the vertical axis Does what you re seeing make any sense to you Now replot the data with frequency along the horizontal axis and amplitude along the vertical axis Does this ma
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