Biorobotics Laboratory BioRob

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Report and presentation

Roombot modules - Kinematics Considerations
for Moving Optimizations
Mikaël Mayer
January 6, 2009


Abstract

The roombots are modular robots being developed by the BIRG team, as the succession of many worldwide attempts to build robots that humans will be using in their tomorrow's house. The new possibilities that they are offering, such as these 6 degrees of freedom when combined in pairs make them good candidates to fulfill the promises that we are expecting from such domestic robots.
Self-reconfiguration is one of the main keywords for these robots. And robustness as well. But for the roombot modules, we still lacked a way to understand their moves good enough so that we would be able to give them complex and automatized tasks.
In this project, we will present the clarification of concepts such as the possible moves in space of the roombot modules, the resolution of inverse kinematics for a lot of potential configurations, and some experiments where we coordinate all previous results and interface them with Webots, a robot-simulation environment.

Videos

The construction of the back of the chair is the main video:

Tiny chair.png 08roombot-back-chair-making.avi
The main video: it tests the locomotion, the reachable space, forward and inverse kinematics, locking and unlocking, in order to let two meta-modules form the back of a tiny chair.


All videos :
Solving FK 01roombot-solvingFK.avi
We present there the first forward kinematics solved in our model..
It means that the meta-module now knows where it is goint to if it modify its angles.
Reconfiguration 02roombot-reconfiguration1.avi
Testing the lock and unlock possibilities, along with movement.
The meta-module is reconfigurated such that  the chain looses one degree of freedom.
The purpose is to recover it.
Solving IK 03roombot-solvingIK.avi
We present here the first inverse kinematics solved in our model.
We can see at some point that one module cannot reach its goal, so it reaches it backwards.
Reachable Z-space 04roombot-reachable-space-Z.avi
Very short video presenting the theoretic reachable "sphere" in space, without self-intersection check, and such that the final position has its Z axis oriented in the same position as the global Z axis.
Reaching grid 05roombot-plan-reachable-space.avi
Quite long video presenting the attemps to reach positions on a grid, thanks to the inverse kinematics.
Reaching grid 06roombot-moving-reachable-space.avi
Exactly the same as the previous video, but this time, it locks and unlocks to move, thus almost randomly, but in a pleasant way.
Acrobats 07roombot-three-modules-reconfiguration1.avi
The acrobats: With an increased torque (the real roombot is not able to lift so many), it presents an exchange of 3 roombots from one position to the other.
Tiny chair.png 08roombot-back-chair-making.avi
The main video: it tests the locomotion, the reachable space, forward and inverse kinematics, locking and unlocking, in order to let two meta-modules form the back of a tiny chair.
Single Roombot 09roombot-one-module-moving.avi
Presentation video to prove that a single roombot module is able to move on its own over a grid of connectors.