Taking your robot for a walk: Force-guiding a mobile robot using compliant arms

Guiding a mobile robot by the hand would make a simple and natural interface. This requires the ability to sense forces applied on the robot from direct physical contacts, and to translate these forces into motion commands. This paper presents a joint-space impedance control approach that does so by perceiving forces applied on compliant arms, making the robot react as a real-life physical object to a user pulling and pushing on one or both of its arms. By independently controlling stiffness in specific degrees-of-freedom, our approach allows the general position of the arms to change to the preferences of the person interacting with it, a capability that is not possible using a strictly position-based control approach. A test case with 15 volunteers was conducted on IRL-1, an omnidirectional, non-holonomic mobile robot, to study and fine-tune our approach in an unconstrained guiding task, making IRL-1 go in and out of a room through a doorway.