Multi-robot system of industrial manipulators coordinated by second-order dynamic couplings

Abstract

This work presents the development of a coordinated system consisting of two ABB industrial robots equipped with force sensors. The function of this system is the gripping and manipulation of objects using a point contact. Being a coordinated system, both robots have access to all the information of their applied force, desired path of the object and position of the end effector of the other robot, unlike a master-slave system where only one robot has the information. Three control schemes are implemented: force-torque control, which allows regulating the penetration generated by the contact on the object, the other one an object position control, whose function is to change the force reference so that with this differential the object manipulation is produced, and a coupling control, whose function is to increase or decrease the force reference, so that the end effectors are always at the same distance (from now on called gripping distance) and a stable grip of the object is ensured. Experimental tests of two types are presented: the first one being the system without the coupling control to see the variation of the grip distance and how it fluctuates
at the moment of the horizontal movement of the object. And the second one, the fully integrated system where it is tested if the control decreases this fluctuation and the grip distance is kept constant.