Control of cooperative multiple flexible joint robots

The problem of controlling multiple flexible joint robots during cooperative manipulation of a rigidly grasped common load (denoted as the CMFJR problem) is addressed. The dynamic model of the CMFJR shows the interaction between the manipulators in the closed chain is analogous to a single manipulator interacting with frictionless (algebraic constraint) surface, while in motion along the surface. It is assumed that each flexible joint robot is equipped with joint velocity and position sensors and also actuator mounted position and velocity sensors. It is shown that it is not necessary to employ force sensors mounted on the robot wrist in order to track a desired load trajectory and an internal force trajectory. The transient response of the position error and the internal force error can be arbitrarily assigned even though the force sensors are not employed