Force-Feedback Device & Deformable Objects

(Diploma Project)

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Description:

Force-feedback devices are used in Virtual Reality to produce a tactile sensation on the user immersed in a virtual environment. Such devices are actually strong mechanical systems able to apply forces onto the user's body such that his/her positions and postures are constrained to the objects of the environment. A person in a virtual environment of an airplane cockpit, for example, can have his/her real arms motion blocked by instruments and walls in certain positions.
A new force-feedback dataglove (pictures above) is now available at the VRlab. This glove is not able to prevent someone to make his/her arms pass through a wall, but in a situation of grasping an object, for example, one can have the motion of his/her hand  limited by the object geometry.

Our lab traditionally works in virtual human bodies representation and motion. Now we are working in deformable models for biological tissues (muscles, cartilage, etc.) based in real material properties and biomechanical parameters. However, such properties and parameters present large variations from one person to another, and consequently their importance to the final behavior of the tissue is not well defined in the biomechanics literature.
The use of force-feedback applied on virtual samples of bio-tissues can help us to configure our deformable models to better fit the real behavior of each different tissue.


The problem

Our biomechanical model will deform according to the external forces acting on it (collision with other objects, gravity, etc.) and the forces produced internally in the tissue as a consequence of the response (reaction) to the external ones.
Thus, the problem to be studied by the student is linking inputs and outputs from the model to the glove and vice-versa.
In this work, the samples of tissue will be simple geometric primitives, like cubes and spheres, and the test situations will be firstly limited to relatively simple situations: touch with one finger (the sample would be on a planar surface), or pressing between two fingers.


Student’s work

The student is asked to implement a set of functions to send forces from the glove to the deformable model, and compute and send to the glove the response forces from the model eventually produced due to collision between the hand and the deformable object (collisions will be detected using an existent library). In other words, the forces produced by the user hand should be passed to the model that will, in turn, deform its geometry and produce reaction forces that should be correctly interpreted by the glove in the form of forces to be applied onto the user hand.
The first task would be calibration of the glove in order to respect the dimensions, position and scale of the virtual tissue model in relation to the real glove and user. In this task, a dinamometer will probably used to validate the applied and produced forces.
The student should also be involved in setting the appropriate user-interface for the sample size and type, and experiment different settings for the tuning of the suitable deformation parameters.

Some resulting demo should be:
- the interactive identification of such parameters for a given tissue (we suggest mashmallow, styrofoam, or some kind of "mousse" for
packaging).
- then using the deformation model alone, try to predict some deformation for different configurations of applied force(s)
- then compare the result of the simulation with what really happens when applying this pattern of forces (interactively with the glove).

The outcome should be to validate/invalidate our deformation model (in a static context).
 
Platform:
PC, C++.

Prerequisite:
Good knowledge in C++.

References:
http://www.immersion.com/products/3d/interaction/cybergrasp.shtml

Note: Project can be done either in English or French.

Responsibles: Anderson Maciel, Sofiane Sarni and Pablo de Heras Ciechomski. Tel: 35248,  Room: INJ 118, Dept: DI
Email:Anderson.Maciel@epfl.ch , Sofiane.Sarni@epfl.ch , Pablo.Deheras@epfl.ch