An event based approach to impact control: theory and experiments

A novel event based motion planning method, together with nonlinear feedback algorithm is applied to the controlled transition between unconstrained and constrained motion of a rigid robotic manipulator. The motion planner is driven by a task related scalar motion reference. This reference is a function of the actual manipulator position in the unconstrained directions and a function of the interaction force in the constrained directions. Impact is considered a discrete event, separating different operation modes. The dynamics of the arm is decoupled with respect to a path-relative representation of manipulator outputs. The feedback control law directly servos these outputs. The event based planning and control scheme was experimentally implemented for impact control and compared with impedance control and explicit force control