E-puck

The e-puck is a small (7 cm) differential wheeled mobile robot. It was originally designed for micro-engineering education by Michael Bonani and Francesco Mondada at the ASL laboratory of Prof. Roland Siegwart at EPFL (Lausanne, Switzerland). The e-puck is open hardware and its onboard software is open source, and is built and sold by several companies.

New modules can be stacked on top of the e-puck; the following extensions are available:

Since the e-puck is open hardware, its price is lower than competitors. This is leading to a rapid adoption by the scientific community in research despite the original educational orientation of the robot. The e-puck has been used in collective robotics[1] [2] [3], evolutionary robotics [4], and art-oriented robotics [5] [6][7].

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Wikipedia