Apparatus and method for providing an adjustable positive stop in space

A robot comprising:

• an end-effector;
• and
• a robot arm comprising a proximal link, a distal link, a joint assembly between the proximal link and the distal link for controlling the relative position of the two links, and a drive mechanism;
• wherein the joint assembly comprises:
• an actuated linkage joint including a pair of stops at a distal end of the actuated linkage joint and controlled by the drive mechanism at a proximal end of the actuated linkage joint;
• and
• a passive linkage joint coupled to the end effector at a distal end of the passive linkage joint and comprising a mechanical positioner at a proximal end of the passive linkage joint, wherein the passive linkage joint moves independently relative to the actuated linkage joint, and wherein the mechanical positioner is located between the pair of stops and moveable between the pair of stops as a user manually moves the end-effector;
• wherein the pair of stops are configured to constrain movement of the mechanical positioner when the mechanical positioner is in contact with one stop of the pair of stops to thereby constrain the ability of the user to manipulate the end-effector outside a predetermined range of motion and to permit movement of the end-effector within the predetermined range of motion as the mechanical positioner moves between the pair of stops and is not in contact with either stop of the pair of stops,
• wherein the drive mechanism is configured to control a location of at least one stop of the pair of stops based on a position of a virtual object in a virtual space, and
• wherein the joint assembly comprises one of a prismatic joint assembly which permits a relative linear motion between the actuated linkage joint and the passive linkage joint, and a revolute joint assembly which permits a relative rotational motion between the actuated linkage joint and the passive linkage joint.