Today I completed the fourth encoder and mounted encoders 2-4 on the front wheels. Next I created a power rail for the encoders and connected them to the Arduino. After testing each encoder to ensure it was working properly, I tested the accuracy of encoders under motion. I noticed some variation between encoders, but even after 20+ meters the difference was minimal unless one of the encoders stopped on the borderline of a segment then it would trigger on/off repeatedly until moved again. I believe this error is due to the relative size of the segments in comparison to the actual encoders and I feel that a form of averaging could be utilized to compensate for the error programmatically.
Now that these encoders are done, I will focus on establishing more robust code to handle both front and rear encoders. While I am waiting for the new encoders to arrive, I will split my focus between refactoring my code and setting up the Sharp Long Range IR Sensors.