Basic Study on Control of Robot Arms Using Joint Torque Sensors

Abstract

Friction in joint driving systems constitutes an important source of nonlinearity that makes it difficult to achieve high-precision control. In this paper, a method of estimating friction is proposed, which requires a joint torque signal, armature current and motor angular velocity. Considering disturbance rejection, a position control method is proposed as follows. Vibration is restrained by bandpass joint torque feedback, and high-precision position control is realized by friction feedforward compensation. Assignment of pole distribution is employed to determine three control coefficients, and the effect of disturbance rejection is compared and evaluated for three kinds of pole distributions. Properties of the proposed control are discussed, and experimental results are also Presented.