The effects of joint flexibility on robot motion control based on joint torque positive feedback

When positive feedback of joint torques is applied to the motion control of robot arms, the nonlinear dynamic couplings between links are canceled and a servo system with high stiffness is obtained. The problems which arise due to joint flexibility in robot motion control based on joint torque positive feedback are discussed. The effects of joint flexibility are investigated by numerical and experimental studies on a one-link arm with a harmonic drive. It is shown that the joint flexibility destabilizes the control system with joint torque positive feedback. A low-pass filter is used in the torque feedback loop to improve the oscillation characteristics of the control scheme.<<ETX>>

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