General adaptive load apportioning for two cooperating robots

The load-sharing-force (LSF) control method for two-arm systems grasping a rigid object is expanded. The LSF control addresses three problems: load sharing; control of interactive forces; and accurate position control. A diagonal matrix α determines how the load is apportioned to each manipulator. An external input specifies the desired compression, tension, or torsion to be applied to the object. An algorithm for the adaptive selection of a diagonal α through the optimization of the joint force distribution over both manipulators is presented. The six diagonal elements of α provide for load apportioning in each of the six spatial degrees of freedom. Accurate position control is obtained by use of reflex-action position control, which makes the manipulator dynamics, as seen by a positron controller, independent of uncertain loading