Biorobotics Laboratory BioRob

Locomotion in Modular Robotics - Roombot Module

Abstract

Roombot module is a modular robot derived at BIRG, EPFL. It has three degrees of freedom and can connect to other Roombot modules by mechanical connectors. A lot of projects have taken place around this new module, covering various aspects like shape and mechanical structure of the module, self-reconfiguration and locomotion of robots made of Roombots modules. The main novelties presented in this project are the implementation of Central Pattern Generator for the command of motors, the introduction of passive elements in the robot structure, and the possibility for a motor to be in constant rotation, as a wheel.

In this project three robots made of Roombot modules and passive elements are tested. A locomotion gait is search for each robot with a different strategy. Strategies are different in the choice of the optimization algorithm (Powell's algorithm, Golden Section Search Algorithm, Systematical Search), the choice of optimized parameters and of course the global structure of the robot. Results are presented for two of the robots, and follow an iterative research. The second strategy is based on the results of the first robot's results, and the third robot and strategy is based on previous results and conclusions.

In general, this project demonstrates that the optimization algorithms used for the robots doesn't succeed in finding an effective locomotion gait. Best results are indeed obtained with manual optimization, without using any optimization algorithm. A really noisy fitness function could explain this failure.

This report presents the three robots tested, the methodology used and the problems encountered, as well as the results of two of the tested robots and a discussion part. The discussion comes back on the choice of an optimization method and on the pattern observed on the result graphics.

Files

• The report (pdf)
• Middle presentation (ppt)
• Middle presentation (pdf)
• Final Presentation (ppt)
• Final Presentation (pdf)

Videos

Chair Robot:

• video 1
• video 2

Table Robot:

• trot gait
• walk gait
• pace gait
• bound gait

Big Chair Robot:

• video3