Towards approximate models of Coulomb frictional moments in: (I) revolute pin joints and (II) spherical-socket ball joints

In general, the rigid-contact assumption has been used to estimate the fric tional moment between two bodies in contact. In a multi-body connection, tw o types of passive interconnection are considered in this paper, namely pin joint and spherical-ball joint. The joints are assumed to be passive at th e localized configuration space of the multi-body systems and are assumed t o be actuated remotely. The traditional approach for modelling such frictio nal contact does not consider the elastic deformation of joints. Two approx imate models are presented for both revolute pin joints and spherical-socke t ball joints. The proposed models offer a more accurate estimation of the Coulomb frictional moment. The new models offer a compact solution which ca n be easily extended to other geometrical multi-body contact configurations with various degrees of clearance. The proposed models can be used in the dynamic modelling and control of multi-body systems in frictional contact.