Modelling and Control of Peg-in-hole Assembly Performed by a Translational Robot

The peg-in-hole insertion is a problem that has been extensively examined in the scientific literature. It represents a generic assembly process of two parts mated by peg-hole couplings. The PMAR Lab group is building the prototype of an innovative high-speed parallel robot for force-controlled applications. Its three-degree-offreedom architecture is characterised by purely translational motion, therefore the main difference between this case and quite all works in literature is the ability of rotating the wrist carrying the peg. For this robot a particular control strategy has been developed, on the basis of the impedance control algorithm, in order to compensate possible errors in the relative position of the peg with respect to the hole, improving the quality of the assembly process. The robot mechanics and the environment have been modelled by means of a multibody simulation package, while the control system and the actuators’ behaviour have been modelled by means of C objects linked to the multibody simulation engine. The same C code that has been used in the simulations will be used for implementation in the prototype control unit, therefore the results of the simulation provide a valid preliminary test for the prototype setup.