Active impedance control design for human-robot comanipulation

The paper describes impedance control techniques for human-robot comanipulation. Active impedance is introduced emerged from classical impedance control. Computed torque methods in the task space powered by multiple-output active observers (AOBs) are addressed for active impedance control, taking into account dynamic and kinematic parameters, as well as stochastic design. The design of constraint and unconstrained directions mapped into arbitrary frames is addressed, being a key feature for advanced comanipulation scenarios. Experiments with a lightweight WAM™ arm are presented for an arbitrary line constraint, highlighting merits of active impedance schemes with respect to classical ones.