Biorobotics Laboratory BioRob

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Neha P Garg- Semester Project (Summer 2007)

Design of a Controller for Crawling to Sitting In a Humanoid Robot

Introduction

The RobotCUB European project [1] aims to study cognitive abilities of a child by building a 2 year old infant-like humanoid robot named iCub. The project has two main goals: first, to create an open and freely available humanoid platform for research in embodied cognition, and second, to study cognitive development. To achieve the goal of cognitive development, it is essential that the robot is able to explore its environment by crawling and sitting just like infants. Therefore, as a part of RobotCUB project, BIRG, EPFL is designing a controller for the locomotion of the robot so that it is able to crawl on its hands and knees just like an infant and should be able to make transition from crawling to sitting position and vise versa.

Controller for locomotion of robot in unpredictable environments is quite a challenging task. The main strength of locomotion of infants lies in the fact that infants are able to do locomotion robustly in almost any kind of environment. It may be possible to design very efficient controllers for locomotion when the external environment is known but such controllers do not have the capability of robust locomotion in new and unpredictable environment. Therefore, understanding the biological mechanisms of locomotion is the key for development of controllers for robust locomotion of autonomous robots. The underlying biological mechanisms by which infants are able to crawl and sit in almost any kind of environment can be learned by modeling the behavior of infants.

A controller for crawling behavior of robot has already been developed in [2] by observation of crawling in real infants. It is based on CPGs which are neural circuits responsible for locomotion found in spinal cord of animals. To design the controller first the crawling behavior of infants was studied and important characteristics of the trajectory were extracted. Then a mathematical model of CPGs based on coupled nonlinear oscillators was developed to reproduce the crawling gait of infants.

The goal of this project is to study the transition from crawling to sitting in infants and to finally design a controller for the robot that would enable it to perform this transition in the same way as infants.

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References

[1] G. Sandini, G. Metta, and D. Vernon, "Robotcub: an open framework for research in embodied cognition," 2004, paper presented at the IEEE-RAS/RJS International Conference on Humanoid Robotics, Santa Monica, CA.

[2] L. Righetti and A.J. Ijspeert. "Design methodologies for central pattern generators: an application to crawling humanoids", Proceedings of Robotics: Science and Systems 2006, Philadelphia, USA

[3] Michel, O. "Webots:Professional Mobile Robot Simulation."Int. J. of Advances Robotic Systems, 2004, pages:39-42,vol.1

[4] G. Metta, G. Sandini, D. Vernon, D. Caldwell, N. Tsagarakis, R. Beira, J. Santos-Victor, A. Ijspeert, L. Righetti, G. Cappiello, G. Stellin, F. and Becchi. "The RobotCub project - an open framework for research in embodied cognition", Humanoids Workshop, Proceedings of the IEEE -RAS International Conference on Humanoid Robots, December 2005