Date: 7/7/05

Student Name: Chris Shepherd

TAs: William Dubel

Steven Pickles

Instructors: A. A. Arroyo

E. M. Schwartz

University of Florida

Department of Electrical Engineering

EEL 5666

Intelligent Machines Design Laboratory

Weekly Report 8 (7/7/05)

The past week was spent working on the final two sensors, the line follower and the color detector. The photo reflectors being used in my line follower are very small and delicate. They do not fit into a standard breadboard, and I broke the legs off of two of them trying to bend the legs to make them fit. Since I could not fit them into a breadboard I cannot fully test the line follower until a custom board is made. However, I was able to set up a single photo reflector to verify its functionality. While the photo reflector produces an analog value, it can be used as a digital sensor since I am only interested in detecting whether I am over a black line or the white floor. While reflecting against a black surface the value was close enough to 5 V to be read as logic high. And while reflecting off of a white surface the output was virtually 0 V, a logic low. Since these are the only two states the sensor will encounter, it will be used as a digital sensor.

The color detector was also tested this week. The color sensor consists of a red, blue, and green LED, and a single CDS cell. The theory behind this sensor is that different objects reflect light of different wavelengths. This is what causes an object to appear the color that it is. For example, a red object appears red in white light because it reflects the wavelengths of light that appear red, and absorbs all the other wavelengths. So, if the same object were placed in green light, it would still absorb all non-red wavelengths, but since this is green light and there are no red wavelengths to reflect, the object would not be able to reflect any light. I use this concept and measure the amount of light reflected under different lighting conditions to determine a color. I used a simple breadboard to construct and test the sensor, and was able to obtain data that proved the functionality of the sensor. This data can be found in my sensor report.