Setting motor speeds

Try to not set motor speeds on every iteration of a loop - receiving motor commands every 20th of a second seems to make the Khepera unhappy, and may lead to problems reading sensor values down the line. Furthermore, sending a command telling the Khepera to set the motor speeds to the same value over and over again isn't very good for the motors, and will probably lead to less than smooth movement.

Some people have suggested just adding a short pause at the end of your loop - this probably isn't the best solution, but if you need something quick and dirty might be worth trying.