Intelligent control of manipulators interacting with an uncertain environment based on generalized impedance

When a manipulator executes a partially constrained task under dynamic interaction with an uncertain environment or arbitrary stiffness, it is required to monitor and control both position and force simultaneously to bring them into acceptable ranges. Generalized impedance control (GIC) is presented as a method of intelligent position and force control of manipulators dynamically interacting with an uncertain environment. The GIC is achieved by representing the desirable behavior of a manipulator end-effector as a general dynamic relationship between a motion error and a contact force error, referred to as generalized impedance. The approach differs from previous manipulator control approaches in that it neither assumes the orthogonality between force and position control nor requires the switching of control for the transition between free and constrained motions. Furthermore, it is robust to the environmental stiffness ranging from zero stiffness (free space) to high stiffness (rigid contact)