[Egg 3141592654]

There are two schools of thought to this, but personally I prefer PID control because I have seen/done it before effectively. If you want pre set positions, I would say that the potentiometer + PID to be the best control system for your robot. Not only will the values stay consistant, the arm will almost always go into the same position (assuming that you don't move the potentiometer (or pot)). The PID function is found under the analog tab. Basically, the set point determines what voltage the pot should read at the desired position, the process variable is the raw instantanious pot reading, the array of 3 values that are used to tune the loop (bottom always 0, mid is 0 or really small, top is the tuning number >0). The top output is the value you set your motors to. It is a bit confusing, pm me if you need examples/extra explination.