Force tracking in multiple impedance control of space free-flyers

The new algorithm of multiple impedance control (MIC) which enforces designated impedance on both a manipulated object, and all cooperating manipulators is applied to a space robotic system in which robotic arms, mounted on a free-flying-base, manipulate an object. A vigorous stability analysis of the MIC algorithm based on Lyapunov direct method, besides error analysis, show that the MIC law guarantees good tracking of cooperative manipulators and the object, in performing a manipulation task. Also, a force tracking strategy inspired by human control system is added to the MIC algorithm and the general formulation is revised to fulfil a desired force tracking task after impact. A system of three manipulators mounted on a space free-flyer is simulated, and the results show that, even in the occurrence of an impact due to collision with an obstacle, the response of the MIC algorithm is smooth. Also, relying on the new modification of the algorithm, the contact force follows successfully a desired tracking trajectory.