CE 351, Fall 2020
Project 5
Name: Cesar Molina
Email: camolina@fortlewis.com

1. Title: PID Control - Photocell

2. Introduction

The purpose of this project was to introduce students to PID controllers while performing different tasks using a photocell and LEDs. The tasks included developing/editing a PID control code to maintain the brightness perceived by the photocell at a specific value or set point. By the end of this project, students gained an ability to code using PID loops and export data from Arduino IDE to a local drive.
 
3. Materials and Methods

Materials

Computer

Arduino IDE

Arduino UNO R3

Photocell

10K Resistor

300 ohm Resistor

Breadboard

Wires

MATLAB

 

The PID control code and circuit connections using a photocell and LEDs was provided by Dr. Li on his webpage and can be found here.

Project 5 consisted of the following tasks:

1.     Make the sensed light to oscillate around a set point.

2.     Repeat the work in Section 3 and plot the data using MATLAB.

3.     Fix the set point function to enable a desired PID control. Plot the set point and the sensor data in the same figure using MATLAB.


4. Results



Figure 1:  Minimum light intensity obtained.



Figure 2:  Maximum light intensity obtained.

 


Figure 3:  Task 1 - Arduino Code.



Figure 4:  Task 1 - Arduino Code Modified.



Figure 5:  Task 1 - Circuit setup.

Figure 6:  Task  1 - Make the sensed light to oscillate around a set point.




Figure 7:  Task 1 - The modification of the PID code was very niosy in comparison with the previous one.



Figure 8:  Task 2 - Circuit setup.



Figure 9: Task 2 - Repeat the work in Section 3 (Adding an extra LED to alter the sensed light by the photocell).



Figure 10: Task 2 -  Plot the data using MATLAB.




Figure 11:  Task 3 - Circuit setup.


Movie 1: Task 3 - Fix the set point function to enable a desired PID control.


Figure 12: Task 3 - Plot the data using MATLAB.



Figure 13: Task 3 - Arduino Code.

 


5. Discussion

All tasks were performed and executed successfully. The modification of the PID code discussed in class brought a lot more noise to the readings than code provided on Dr. Li’s webpage. For this reason, I decided to use the webpage’s code for Task 2 and 3. The excel data streamer was also used to stream data from arduino to excel and then import it to MATLAB. The ability to use PID controllers and understand their feedback loop mechanism will be very useful for students throughout their engineering careers.