Transient Lateral Motion of Robots in Part Mating

This paper is concerned with achieving a higher rate at which a robot operation involving part mating can be carried out while free of excessive contact forces. It is shown that the rate is primarily limited by the robot end effector's lateral transient response to the contact forces, while the response depends mainly on the link inertia characteristics and joint compliances. Both factors were modelled and simulated for robots of SCARA configuration for the chamfercrossing stage. The transient response predicted by the model led to determination of a varying-speed insertion motion for the chamfer-crossing stage to avoid large initial impacts between peg and hole and to limit the contact force during the entire stage. The discrepancy angle between the contact force and the resultant lateral motion was also considered. Good agreement was obtained between the transient response predicted in simulation and that observed in experiment.