ARM Techcon / mbed Robot Racing

Ok today I was at ARM Techcon saw mBed Robot Racing gave it a try. Let me tell you drive it with the  Archos Android Tablet Hard for me. I betting with time I get better. 1st run with Tablet was sad 80 plus seconds. 2nd run was far better 22 seconds. Ok now to the closed loop control. The 1st few try where let say bad.  Asked people from Pololu answer a few of my question on the line sensors.Went to a few classes at ARM Techcon need less to say I could not get the problem out of my head. PID was the answer I told my self it it should allow me to increase the speed of the Robot.

PID stands for Proportional, Integral, Derivative; these are the three input values used in a simple formula to compute the speed that your robot should turn left or right.


  • The proportional value is proportional to the robot position with respect to the line. That is, if the robot is precisely centered on the line, we expect a proportional value of exactly 0. If it is to the left of the line the proportional term will be a positive number, and to the right of the line, it will be negative. (-1 to 1) is the position of the robot
  • The integral value records the history of your robot’s motion: it is a sum of all of the values of the proportional term that were recorded since the robot started running.(I had problem get this work right so set the gain to zero)
  • The derivative is the rate of change of the proportional value. We compute it in this example as the difference ofthe last two proportional values.


I should write this up more but it was a long drive home from ARM Techcon (3 hours should have been only 1.5 hours)


Ok forgot this did put me in 1st place 4.8 seconds . I not sure if it will hold if someone get a full PID and the Term right they could beat my time. Fully charged Battery could be my time.


Thanks to the mBed Robot Racing group. This was great!

Thanks to bill help me with the code.


mbed Robot Racing - The results


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