Passive robotic constraint devices using non-holonomic transmission elements

An apparatus comprising:

• at least one steerable non-holonomic transmission element which couples two or more directional velocities of motion via a steering angle;
• a motor for adjusting the steering angle of the at least one non-holonomic transmission element;
• a memory which stores a description of a virtual surface;
• and
• a computer for controlling the steering angle of said at least one non-holonomic kinematic transmission element in order to prohibit any motion of the passive constraint device which would penetrate the virtual surface.

A method for controlling a robotic device having a plurality of joints coupled together by at least one steerable non-holonomic transmission element, comprising:

• storing a virtual surface;
• determining the position and speed of the robotic device;
• measuring the force applied by an operator to the robotic device;
• adjusting a steering angle of said non-holonomic transmission element so as to prohibit any motion of the robotic device that would penetrate said virtual surface when said robotic device is in contact with said virtual surface;
• and
• adjusting a steering angle of said non-holonomic transmission element so as to provide apparent freedom of motion to a user when said robotic device is not in contact with said virtual surface.

A method for controlling a robotic device having a plurality of joints coupled together by at least one steerable non-holonomic transmission element, comprising:

• storing a path to be followed by the robotic device;
• determining the position and speed of the robotic device;
• measuring the force applied by an operator to the robotic device;
• continuously adjusting the steering angle of said non-holonomic transmission element as said robotic device is moved along said path by an operator so that the robotic device will move smoothly along said path.

An apparatus comprising:

• an endpoint movable by an operator in a plurality of directions;
• at least one non-holonomic transmission element which couples a velocity of said endpoint in one of said directions with a velocity of said endpoint in another of said directions, said nonholonomic kinematic transmission element having a steering angle which controls a ratio of said velocities, whereby mechanically allowed directions of motion of said endpoint are dictated by the steering angle of said at least one non-holonomic transmission element;
• and
• a computer, connected to said motor and said at least one non-holonomic transmission element, which controls the mechanically allowed directions of motion through space of the endpoint by adjusting the steering angle of said at least one non-holonomic kinematic transmission element.