Passivity-based design and experimental validation of adaptive force/position controllers for robot manipulators

This paper deals with the problem of controlling the interaction of a robot manipulator with an elastic surface. The goal of tracking a desired position trajectory and a desired time-varying contact force is pursued. The controller design is carried out in a passivity framework and adaptive algorithms are used to counteract the effects of the uncertain estimate of the stiffness coefficient of the environment. Two alternative adaptive control laws are considered, with and without force time-derivative feedback. The experimental validation is carried out on an industrial robot with open control architecture equipped with a force sensor.