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.
Diameter: 70 mm
Height: 50 mm
Weight: 200 g
Max speed: 13 cm/s
Autonomy: 2 hours moving
dsPIC 30 CPU @ 30 MHz (15 MIPS)
8 KB RAM
144 KB Flash
2 step motors
8 infrared proximity and light (TCRT1000)
color camera, 640x480
8 LEDs in ring + one body LED + one front LED
E-puck mobile robot Wikipedia
New modules can be stacked on top of the e-puck; the following extensions are available:a turret that simulates 1D omnidirectional vision, to study optic flow,
ground sensors, for instance to follow a line,
color LED turret, for color-based communication,
2D omnidirectional vision,
magnetic wheels, for vertical climbing.
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  , evolutionary robotics , and art-oriented robotics  .