New results in adaptive impedance control of manipulators

Presents two adaptive schemes for controlling the end-effector impedance of dexterous manipulators to enable reliable execution of contact tasks. The first scheme is position-based adaptive impedance control and consists of two subsystems: a simple “filter” which modifies the end-effector position trajectory based on the sensed contact force and the desired dynamic relationship between the position and force, and an adaptive controller that produces the joint torques required to track this modified trajectory. The second control strategy is developed using a model reference adaptive impedance control approach by formulating the desired relationship between the end-effector position and contact force as a “reference model”, and then devising a control scheme to ensure that the end-effector dynamics emulates this reference model. The proposed controllers are computationally efficient, do not require knowledge of either the mathematical model or the parameter values of the robot dynamics or the environment, and are shown to be globally stable in the presence of bounded disturbances