Collision handling by a robot

Abstract

The invention relates to a method of collision handling for a robot with a kinematic chain structure comprising at least one kinematic chain, wherein the kinematic chain structure includes: a base, links, joints connecting the links, actuators and at least one end-effector, a sensor Sin the most distal link of at least one of the kinematic chains for measuring/estimating force/torque, and sensors Sfor measuring/estimating proprioceptive data, wherein the sensors Sare arbitrarily positioned along the kinematic chain structure, the method including: providing a model describing the dynamics of the robot; measuring and/or estimating with sensor Sforce/torque Fin the most distal link of at least one of the kinematic chains; measuring and/or estimating with the sensors Sproprioceptive data: base and robot generalized coordinates q(t) and their time derivative {dot over (q)}(t), generalized joint motor forces τ, external forces F, a base orientation φ(t) and a base velocity {dot over (x)}(t); generating an estimate {circumflex over (τ)}of the generalized external forces τwith a momentum observer based on at least one of the proprioceptive data and the model; generating an estimate {umlaut over ({circumflex over (q)})}(t) of a second derivative of base and robot generalized coordinates {umlaut over (q)}(t), based on {circumflex over (τ)}and τ; estimating a Cartesian acceleration {umlaut over ({circumflex over (x)})}of point D on the kinematic chain structure based on {umlaut over ({circumflex over (q)})}(t); compensating the external forces Ffor rigid body dynamics effects based on {umlaut over ({circumflex over (x)})}and for gravity effects to obtain an estimated external wrench {circumflex over (F)}; compensating {circumflex over (τ)}for the Jacobian Jtransformed Fto obtain an estimation {circumflex over (τ)}of generalized joint forces originating from unexpected collisions; detecting a collision based on given thresholds τand Fif {circumflex over (τ)}>τand/or if {circumflex over (F)}>F.