1. Haptic Systems
Mohsen Mahvash
Lecture 7
18/1/06

2. Haptic rendering of contact
A review of the last lecture
Change of force at the edges
Force shading
Friction rendering
References

3. A review of last lecture

4. Change of force direction
During sliding contact, at the moment that the god-object is crossing an edge, the direction of force changes.

5. Change of force amplitude
During sliding contact, at the moment that the god-object is crossing an edge, the amplitude of the force changes.

6. Vertex normal

7. Vertex local surface
A local coordinate can be defined at each vertex of the object

8. local coordinates at contact points
The direction of normal vector smoothly changes during sliding contact
Local surfaces at different contact points

9. Proxy location proxy Local surface tip project Object surface tip
tip project: the closest point of the local surface to the tip
proxy: the closest point of the active surface to the tip project

10. A friction model for haptic rendering
Coulomb model
A friction model for haptic rendering

11. Friction rendering
Local surface
Object surface

12. References:
C.B. Zilles, J.K. Salisbury, A constraint-based god-object method for haptic display International Conference on Intelligent Robots and Systems-Volume 3.  1995.
D. C. Ruspini, K Kolarov, O Khatib - The haptic display of complex graphical environments, SIGGRAPH, 1997.
Mahvash, M., Hayward, V High Fidelity Haptic Synthesis of Contact With Deformable Bodies. IEEE Computer Graphics and Applications. 24(2): 48-55, 2004.
V Hayward, B Armstrong, A New Computational Model of Friction Applied to Haptic Rendering, Lecture Notes in Control and Information Sciences, Vol. 250, Springer-Verlag, pp
Tomorrow
 Haptic assistance: Applications and Design Considerations (guest lecturer Panadda Marayong)