The control of contact forces as related to safe robot/human interaction

In industrial robotic applications, robots are segregated from humans. Light curtains are used to power-down the robot if a human comes into its workspace. For advanced interaction with humans, it will be necessary to control contact forces. During in-contact operations, a planar manipulator will have a reduced degree of freedom of motion (3-n) combined with an n degree of constraint contact wrench space. The problem is how to control the manipulator to simultaneously control the contact force/torque as it moves through its allowable motion space. This paper describes the Theory of Kinestatic Control whereby a compliant element is introduced between the manipulator end-effector and the environment. Knowledge of the compliant characteristics of this element allows for the determination of end-effector wrenches that will only cause movement without changing the contact force/torque and end-effector wrenches that will only cause changes in the contact force/torque while producing no motion. A sample implementation is presented.