InitRech 2015/2016, sujet 3
Sommaire
Domain decomposition approach for FEM quasistatic modeling and control of Continuum Robots with rigid vertebras
Summary
Robots are more and more used in today's life. If in a first time robots were static, we are now using movable robots. More precisely we are studying robots with the capability of deform themself. Those kind of robots are named continuum robots.<br\> The continuum robots are inspired by biological attributes like tongue, tentacles or vertebras. In general the continuum robots are all around a backbone who can be deform for reach the desired position. The 3 more common continuum robots's structure are :
- 1 - The concentric-tube type
- 2 - The tendon actuated type
- 3 - The pneumatic actuated type
<br\>The main particularity of continuum robots is the absence of discrete parts and their numerous degree of liberty who permit to deform themself.
Main Contribution
This paper illustrate a new approach based on finite element method (FEM) for taking into account the internal forces of the robots on the deformation of their structure. Even if this method is in general very time consuming it can be used for modeling soft-robot.<br\> This paper is focused on continuum robots made of a slender structure and studying the main axis deformation instead of the whole volume. This volum is modelized thanks to a Block-Tri-Diagonal solver.<br\> A main important part of this modelling is to discretize the deformation of the continuum robots. It's possible thanks to a set of nodes with 6 degrees of liberty, called frames,aligned all along the principal axis of the continuum robot.<br\> The resistance and the deformation of the robot is calculated with matrix who represent some physics based on continuum mechanics. This permit to calculate on each node the deformation of the robot and with the block-tri-Diagonal solver to enlarge this at the whole volume. The main problem is to simplificate as much as possible the calculation to stay in a real-time interaction but to be as specific as possible to the real movement.
Applications
Continuum robots, thank to their deformation, would be used in most of the high precision fields like surgery. It can also be used in some fields were ther are specific mechanical constraint. In effect the deformation of continuum robot looks important when you have to be also flexible and robust. This utilisation can be used in aerospatial for example, imagine a arm that can cumulate many functions thnaks to his modification of form and solidity.<br\> However the main applications would be the replacement of humans organs or members, we couls recreate the texture and the mobility of a member thanks to this technology an dit's one of the most research utility searched for this field of technology.
