A New Approach to Control Single-Link Flexible Arms. Part 1. Modelling and Identification in the Presence of Joint Friction

摘要

Abstract : This report presents a new way to model and identify single-link flexible arms when Coulomb friction is present in the joint. In order to isolate the effects of this nonlinearity, the arm model is divided into two submodels: motor and beam. The two are coupled through the torque at the base of the beam. A systematic method is developed to obtain the dynamics of a lumped-mass flexible beam, and some properties are obtained from this model. The influence of the payload on the model is given special attention. This way of modelling is later extended to the general case of distributed-mass flexible arms. Identification in the presence of Coulomb friction is carried out. A new method is proposed to estimate this friction and to reconstruct the motor frequency response from experimental results, which are highly distorted by this nonlinear friction. Single-link; Flexible arms; Motor; Beam; Torque; Coulomb friction; Motor frequency response; Robotics.