Dynamics modelling and hybrid control of the 6-UPS platform

The article presents the inverse dynamics model of a 6-Universal-Prismatic-Spherical (UPS) parallel mechanism and proposes the structure of a force controller for the execution of tasks characterized by interaction with the environment. The task space model of machine's dynamics is obtained in an efficient and compact form by means of the principle of virtual work. A simulation is shown that hybrid position/force control schemes should be able to provide good performances for medical diarthrosis rehabilitation.