Redundant underactuated robot with multi-mode control framework

A method for controlling a jointed mechanism having a multi-axis robot and a passive pendulum system attached thereto and suspended therefrom, the method comprising:

• measuring rotational joint positions on the passive pendulum system using a plurality of position sensors;
• outputting position signals indicative of the rotational joint positions to a controller;
• and
• in response to the position signals, using the controller to selectively control motion of the robot in a plurality of control modes, including:
• a Cooperative Mode configured, in response to a physical interaction by a human operator with the end-effector, to cause a displacement in the passive pendulum system from an equilibrium position, and in which the controller is configured to command the robot to move in such a manner as to close the displacement and thereby return the passive pendulum system to the equilibrium position;
• and
• an Autonomous Mode configured to move the robot without a physical interaction with the end-effector by the human operator, wherein the controller is configured to detect unexpected contact with the end-effector when operating in the Autonomous Mode, and to automatically initiate a control action in response to the contact, wherein detecting the unexpected contact is based on a deviation of a measured joint motion of the passive pendulum system from an expected joint motion.

A jointed mechanism comprising:

• a horizontal overhead support beam;
• a robot, including an actuated positioning mechanism connected to and configured to translate along the overhead support beam in two Cartesian degrees of freedom;
• a passive parallelogram arrangement attached to and suspended from the actuated positioning mechanism, having an equilibrium position, and including:
• one or more position sensors configured to measure one or more joint angles on the passive parallelogram arrangement;
• parallel arms;
• a cross member connected to the parallel arms;
• and
• an end-effector attached to the cross member at a distal end of the passive parallelogram arrangement;
• and
• a controller in communication with the one or more position sensors, wherein the controller is configured, in response to the one or more joint angles, to selectively control the passive parallelogram arrangement in a plurality of control modes, including:
• a Cooperative Mode configured, in response to a physical interaction by a human operator with the end-effector, to cause a displacement in the passive parallelogram arrangement from the equilibrium position, and in which the controller is configured to command the robot to move in such a manner as to close the displacement and thereby return the passive parallelogram arrangement to the equilibrium position;
• and
• an Autonomous Mode configured to move the robot without a physical interaction with the end-effector by the human operator, wherein the controller is configured to detect unexpected contact with the end-effector when operating in the Autonomous Mode based on a deviation of a measured joint motion of the passive pendulum system from an expected joint motion, and to automatically initiate a control action in response to the unexpected contact.