ME 333 Lab 4 - Revision history

Andrew Long: /* Feedback Controller */

2010-01-26T00:41:25Z

Feedback Controller

Andrew Long: /* RS232 */

2010-01-25T19:50:15Z

RS232

NickMarchuk at 15:47, 25 January 2010

2010-01-25T15:47:31Z

NickMarchuk at 15:47, 25 January 2010

2010-01-25T15:47:11Z

NickMarchuk at 15:45, 25 January 2010

2010-01-25T15:45:37Z

NickMarchuk: /* Feedback Control */

2010-01-24T20:41:48Z

Feedback Control

NickMarchuk: /* Feedback Control */

2010-01-24T20:37:14Z

Feedback Control

NickMarchuk: /* Feedback Control */

2010-01-24T20:36:39Z

Feedback Control

NickMarchuk: /* Programming Summary */

2010-01-24T20:35:12Z

Programming Summary

NickMarchuk: /* RS232 */

2010-01-24T20:33:39Z

RS232

@@ Line 378: / Line 378: @@
 We are now going to create our proportional controller for the getPWMmagn() function.
 *Put the following line of code in the "Function Declarations" section:
- int getPWMmagn(signed int error);
+ unsigned int getPWMmagn(signed int error);
 This function returns the magnitude of the pwm signal.

@@ Line 575: / Line 575: @@
  	recordData = FALSE;
  	recordIndex = 0;
- 	for(i = 0; i < NUM_COUNTS; i++)
+ 	for(i = 0; i < NUM_DATA_POINTS; i++)
  	{
  		sprintf(RS232_Out_Buffer,"%d %d\n",encoderCounts[i], referenceData[i]);

@@ Line 1: / Line 1: @@
 In this lab, we are going to use the PIC32 microcontroller to control the motor's position with a proportional feedback controller. Review the lecture on Timers, Interrupts and PWM and what this lab is about on [[Media:Timers_Interrupts_PWM.pdf | this pdf]]. A block diagram of the overview of this lab is shown below.
 [[Image: Lab4_Feedback.jpg]]
 <br>

@@ Line 1: / Line 1: @@
-In this lab, we are going to use the PIC32 microcontroller to control the motor's position with a proportional feedback controller. A block diagram of the overview of this lab is shown below.
+In this lab, we are going to use the PIC32 microcontroller to control the motor's position with a proportional feedback controller. Review the lecture on Timers, Interrupts and PWM and what this lab is about on [[Media:Timers_Interrupts_PWM.pdf | this pdf]]. A block diagram of the overview of this lab is shown below.
 [[Image: Lab4_Feedback.jpg]]
 <br>
-Review the lecture on Timers, Interrupts and PWM and what this lab is about on [[Media:Timers_Interrupts_PWM.pdf | this pdf]].
 The PIC32 is going to generate a square wave reference signal (ref) that will cause the motor to alternate between two positions. This reference signal could be changed to any arbitrary signal such as a sinusoid or a triangle wave, but for this lab we are going to stick with a square wave. The period and amplitude will be set by your PC, communicating with the PIC32.

@@ Line 2: / Line 2: @@
 [[Image: Lab4_Feedback.jpg]]
 <br>
+Review the lecture on Timers, Interrupts and PWM and what this lab is about on [[Media:Timers_Interrupts_PWM.pdf | this pdf]].
 The PIC32 is going to generate a square wave reference signal (ref) that will cause the motor to alternate between two positions. This reference signal could be changed to any arbitrary signal such as a sinusoid or a triangle wave, but for this lab we are going to stick with a square wave. The period and amplitude will be set by your PC, communicating with the PIC32.

@@ Line 623: / Line 623: @@
 Visit [http://processing.org/ Processing.org] and download and install Processing ([http://processing.org/download/index.html download Processing]). Processing is an easy to learn IDE based on Java. We will use it to open a serial port on your PC and communicate with the PIC32. Encoder data from the PIC32 will be plotted when you hit a button in Processing.
-Download [[Media:processing_lab4.zip | this zip]]. Put this in Processing folder in My Documents. Open me333_lab4.pde. This code will do all the work for you, we will go over how to code in Processing soon.
+Download [[Media:processing_lab4.zip | this zip]] containing the Processing code and images for this lab. Unzip processing_lab4.zip in the Processing folder in My Documents. Open Processing and select File->Open and navigate to me333_lab4.pde. This code will do all the communication and plotting work for you. We will go over how to write your own code in Processing soon.
 The only thing you may have to change in this code is which COM port to use. Follow the documentation in the code or see the TA if you need to change the COM port.
@@ Line 631: / Line 631: @@
 [[Image:processing_motor_control.jpg]]
-*p should collect 640 data points at 1kHz and plot the encoder position and reference position so you can see how well your controller is doing
+*p collects 640 data points at 1kHz and plots the encoder position and reference position so you can see how well your controller is doing
 *f will increment Kp by 1
 *b will decrement Kp by 1
@@ Line 637: / Line 637: @@
 *w will decrement amplitude by 25
-Play around with your PIC and Processing code. Bring your circuit and code to Lab and demonstrate it to the TA. Turn in your PIC main.c code and several screenshots of your controller from Processing.
+Play around with your PIC and Processing code.
+Bring your circuit and code to Lab and demonstrate it to the TA. Turn in your PIC code and several screenshots of your controller from Processing.

@@ Line 619: / Line 619: @@
 Lets play with the proportional gain on of the controller and see how it effects the output position of the motor shaft.
-In an analog controller, you can watch the effect of changing the gain on an oscilloscope. On a digital controller, we will save encoder positions and report them back to the PC for plotting.
+In an analog controller, you can watch the effect of changing the gain on an oscilloscope. On a digital controller, we must save encoder positions in memory and report them back to the PC for plotting.
 Visit [http://processing.org/ Processing.org] and download and install Processing ([http://processing.org/download/index.html download Processing]). Processing is an easy to learn IDE based on Java. We will use it to open a serial port on your PC and communicate with the PIC32. Encoder data from the PIC32 will be plotted when you hit a button in Processing.

@@ Line 617: / Line 617: @@
 =Feedback Control=
-Lets play with the proportional gain on of the controller.
+Lets play with the proportional gain on of the controller and see how it effects the output position of the motor shaft.
 In an analog controller, you can watch the effect of changing the gain on an oscilloscope. On a digital controller, we will save encoder positions and report them back to the PC for plotting.

@@ Line 598: / Line 598: @@
 **Calculate Error and PWM based on Proportional Controller
 *RS232 Interrupt to:
-**Reset the Period and Amplitude of square wave
 **Increase or decrease the proportional gain, kp
+**Increase or decrease the amplitude of the reference signal
 **Initiate storage and printing of data
-*Store on the PIC32 and Print X number of data points to the terminal
+*Store on the PIC32 and Print 640 data points to the PC
 While creating this code, you have seen how to create interrupts and create modular code.

@@ Line 584: / Line 584: @@
 In a for loop, the encoder count and reference data is sent to the PC.
 This function will not be interrupted because it is currently being called in a high priority interrupt, so our 1kHz control algorithm will not operate. The PWM sent to the motor when sendDataRS232() is called will remain, which is not desirable, so we set the motor direction to forward and the PWM to 0 before calling sendDataRS232(), to stop the motor before sending data.
-You can manipulate this data using excel or processing as discussed in the next section.
 ==Programming Summary==