Experimental study on torque control using harmonic drive built-in torque sensors

The authors have proposed a torque sensor which utilizes elasticity of harmonic drives. The characteristics of joint torque control were experimentally examined using this torque sensor. Three types of torque control laws were implemented with a one-link arm to find a control method which provides excellent friction reduction and dynamic response in joint torque. The experimental results of the joint torque control showed that the torque sensor was very useful for compensating for the nonlinear friction. The torque control was effective in improving the accuracy of motion control at low velocity and suppressed the vibration caused by the joint flexibility