What kind of motors do industrial robots use and how do you control them?
Most industrial robot have servo motors. This allows you to control velocity, torque and position of motors - the latter usually in some form of closed-loop control system.
I work for Stäubli. Our early robots were actually hydraulic, the UniMate. Next were the PUMA robots which had DC servo motors. The modern RX, TX, TX2, TS, and TS2 arms have 3-phase AC servo motors.