1 Haptic Systems 530-655 Mohsen Mahvash Lecture 3 11/1/06.
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Transcript of 1 Haptic Systems 530-655 Mohsen Mahvash Lecture 3 11/1/06.
2
A review of the last lecture
The definition of haptic rendering
Haptic simulation of a spring
Haptic simulation of the gravitational forces between two objects
Examples of force functions
Haptic rendering of contact
Physically based haptic rendering and the challenges
References
Introduction to Haptic Rendering
4
“Haptic rendering is the process of computing and generating forces in
response to user interaction with virtual environment”
Computing forces and torques that should be applied to the tip of the
haptic display in order to represent forces of a physical phenomena
or represent some data
Tip
The definition of haptic rendering
F
F
5
Haptic Simulation of a Spring
Fp
0p0ppd
kdF ),,( 321 ntipPositiop
Algorithm for
simulation of spring
}0,0,0{0 p
0ppd kdF FJ T
//Virtual spring
i
ii kI
6
Haptic simulation of the gravitational forces between objects
0c
0cpd
dud
kF
2||
|| d
dud
p
R
Rd ||For
For Rd || dkF 2
d
7
Haptic simulation of the Solar System
321 FFFF
p 2c
1c3c
Calculate gravitational forces for every sphere and then add
8
Examples of force functions
)(tfF A function of time
A function of tip position or tip displacement of time )( 0ppfF
A function of tip Velocity)(
dt
dpfF
),,,(2
2
0 dt
dp
dt
dppptfF A general function
You may not be able to implement some general functions
(Because of high order derivatives)
10
Haptic simulation of contact
nudkcpkF ||)( 11
1c1p0c
0p
1c
nu
c
tt uucpc )).(( 01 0t 1t
|| d
1p :unit vector normal to surfacenu
tu
:unit vector tangent to surfacetu
1p
11
Haptic simulation of contact
Haptic Scene
Rigid or Deformable
Graphic Scene
Deformable objectGraphic Scene
Rigid object
12
Rigid and Deformable Objects
Deformable bodies: Location , geometry, frictional properties
, material, support, internal structure
Rigid bodies: Location, geometry and
frictional properties
)( 0cpkF
),,( 00 cdt
dpcpfF
0cp
Elastic material
Viscoelastic
material
),( 00 ccpfF
Plastic
material
14
Physically Based Haptic Rendering and the Challenges
Rendering forces should depend on material properties
It is very time-consuming to calculate rendering forces from material properties using conventional engineering approaches such as Finite Element Methods
15
Tomorrow
Real-time programming for haptics
References
1. Salisbury, K., Brock, D., Massie T., Swarup, N., Zilles, C. 1995. Haptic Rendering: Program-ming Touch Interaction with Virtual Objects. Proc. Symposium on Interactive 3D Graphics, ACM. pp. 123-130
2. 3D Touch™ SDK OPENHaptics™TOOLKIT, Programming Guide, http://www.sensable.com/
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