Haptic Systems 530 655 Mohsen Mahvash Lecture 7

Haptic Systems 530 -655 Mohsen Mahvash Lecture 7 18/1/06 1

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

A review of last lecture 3

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

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

Vertex normal 6

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

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 project: the closest point of the local surface to the tip proxy: the closest point of the active surface to the tip project 10

Friction model Coulomb model A friction model for haptic rendering 11

Friction rendering Local surface Object surface 12

References: 1. 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. 2. D. C. Ruspini, K Kolarov, O Khatib - The haptic display of complex graphical environments, SIGGRAPH, 1997. 3. Mahvash, M. , Hayward, V. 2004. High Fidelity Haptic Synthesis of Contact With Deformable Bodies. IEEE Computer Graphics and Applications. 24(2): 48 -55, 2004. 4. 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. 403 -412. Tomorrow Haptic assistance: Applications and Design Considerations (guest lecturer Panadda Marayong) 13