Force feedback haptic interface for a three-dimensional CAD surface

A method for providing a haptic interface between a physical device and a computer generated parametric surface separating a virtual space into two virtual half spaces, the physical device capable of transmitting forces in at least three degrees-of-freedom via a force actuation mechanism connected thereto and defining a plurality of device points when moved through the virtual space, the method comprising the steps of, for each of the plurality of device points:

• (i) deactivating the force actuation mechanism and proceeding to a next of the plurality of device points if a minimization point on the parametric surface which minimizes the distance between a device point and the parametric surface is a boundary point;
• (ii) deactivating the force actuation mechanism and proceeding to a next of the plurality of device points if the device point is outside of a predetermined elasticity zone around the parametric surface;
• (iii) deactivating the force actuation mechanism and proceeding to a next of the plurality of device points if the device point is separated from the parametric surface;
• (iv) determining a force to apply to the physical device, activating the force actuation mechanism so as to produce the force at the physical device, and proceeding to a next of the plurality of device points if the device point has moved along the parametric surface;
• and
• (v) determining a force to apply to the physical device, activating the force actuation mechanism so as to produce the force at the physical device, and proceeding to a next of the plurality of device points if the device point has passed through the parametric surface.