Multi-Rate Rendering:
The required force update rate for stable real time interaction in a
surgical simulation is very high. Majority of force feedback devices have
at least a few hundred Hz update rates, which is comparably larger than
the visual update rate. There is large difference between the update rate
of the devices and the update rate of our scene ensuring physically realistic
behavior. Consequently, we should consider a multi-rate rendering scheme
when the various modalities are involved in the system. We have developed
an interpolation or extrapolation scheme to generate continuous forces
for force-feedback devices.
Collision prediction:
In rendering of deformable object haptically and visually in real time,
collision detection and collision response from the model are the dominating
tasks in the computation. Because two tasks are both computationally expensive
and need high update rates, two tasks have a trade-off relationship that
limits the performance of whole system. The collision prediction removes
this trade-off relationship by separating two tasks. We have developed
a collision detection scheme exploiting the fact that the user’s hands
holding the force-feedback devices have low frequency motion (of the order
of 10Hz or less) compared to the sampling frequency of the system (100
to 1000Hz), the approach direction of the tools can be computed from the
trajectories.
Publications:
Kim J, De S, and Srinivasan MA (2002), Computationally Efficient Techniques
for Real Time Surgical Simulation with Force Feedback, IEEE Virtual Reality
Conference.
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