Encoders count the rotations of the four wheels at 40 Hz. The encoder counter is reset after each reading. For example, if one rotation corresponds to meters traveled, five consecutive encoder counts of 0, 1, 0, 2, 3 correspond to (0 1 0 2 3) = 2 meters traveled for that wheel. The data sheet indicates that the wheel diameter is 0.254 m and since there are 360 ticks per revolution, the wheel travels 0.0022 meters per tic. Given encoder counts [F R, F L, RR, RL] corresponding to the front-right, front-left, rear-right, and rear-left wheels, the right wheels travel distance (F R RR)/2 0.0022 m, while the left wheels travel distance (F L RL)/2 0.0022 m