Active-constraint robots

A method of controlling an active-constraint robot, comprising:

• providing an active-constraint robot (4) including a tool (14) for operating on element, and a drive unit (20,28,38) for controlling movement of the tool;
• providing a model including a model surface describing a constraint surface associated with the element;
• determining the imaginary point (I) of intersection of a force vector (V) representative of a force applied by a user to the tool and the model surface;
• and
• controlling the drive unit (20,28,38) by resisting movement of the tool according to the determined point of intersection.

An active-constraint robot (4) including:

• a tool (14) for operating on an element;
• a drive unit (20,28,38) for controlling movement of the tool;
• means for holding a model including a NURBS surface describing a constraint surface associated with the element;
• means for determining the imaginary point (I) of intersection of a force vector (V) representative of a force applied by a user to the tool and the NURBS surface;
• and
• a control for controlling the drive unit (20,28,38) by resisting movement of the tool according to the determined point of intersection.

An active-constraint robot (4) including:

• a tool (14) for operating on an element and a drive unit (20,28,38) for controlling movement of the tool;
• means for holding a model including a model surface describing a constraint surface associated with the element;
• means for determining the imaginary point (I) of intersection of a force vector (V) representative of a force applied by a user to the tool and the model surface;
• and
• a control for controlling the drive unit (20,28,38) by resisting movement of the tool according to the determined point of intersection.

A method of controlling an active-constraint robot, comprising:

• providing an active constraint robot (4) including a tool (14) for operating on an element, and a drive unit (20,28,38) for controlling movement of the tool;
• providing a model describing a constraint surface associated with the element;
• and
• controlling the drive unit by resisting movement of the tool in a direction tangential to an adjacent constraint surface in dependence upon the shape of the constraint surface in a region surrounding the position of the tool.

An active constraint robot (4) including:

• a tool (14) for operating on an element;
• a drive unit (20,28,38) for controlling movement of the tool;
• means for holding a model describing a constraint surface associated with the element;
• and
• control means for controlling the drive unit by resisting movement of the tool in a direction tangential to an adjacent constraint surface in dependence upon the shape of the constraint surface in a region surrounding the position of the tool.