iCub

An iCub robot mounted on a supporting frame. The robot is 104 cm high and weighs around 22 kg

An iCub is a 1 metre high humanoid robot testbed for research into human cognition and artificial intelligence.

It was designed by the RobotCub Consortium, of several European universities and is now supported by other projects such as ITALK. The robot is open-source, with the hardware design, software and documentation all released under the GPL license. The name is a partial acronym, cub standing for Cognitive Universal Body. Initial funding for the project was €8.5 million from Unit E5 – Cognitive Systems and Robotics – of the European Commission's Seventh Framework Programme, and this ran for six years from 1 September 2004 until 1 September 2010.

The motivation behind the strongly humanoid design is the embodied cognition hypothesis, that human-like manipulation plays a vital role in the development of human cognition. A baby learns many cognitive skills by interacting with its environment and other humans using its limbs and senses, and consequently its internal model of the world is largely determined by the form of the human body. The robot was designed to test this hypothesis by allowing cognitive learning scenarios to be acted out by an accurate reproduction of the perceptual system and articulation of a small child so that it could interact with the world in the same way that such a child does.

Specifications

An iCub at a live demo making facial expressions

The dimensions of the iCub are similar to that of a 3.5 year old child. The robot is controlled by an on-board PC104 controller which communicates with actuators and sensors using CANBus.

It utilises tendon driven joints for the hand and shoulder, with the fingers flexed by teflon-coated cable tendons running inside teflon-coated tubes, and pulling against spring returns. Joint angles are measured using custom-designed Hall-effect sensors and the robot can be equipped with torque sensors. The finger tips can be equipped with tactile touch sensors, and a distributed capacitive sensor skin is being developed.

The software library is largely written in C++ and uses YARP for external communication via Gigabit Ethernet with off-board software implementing higher level functionality, the development of which has been taken over by the RobotCub Consortium. The robot was not designed for autonomous operation, and is consequently not equipped with onboard batteries or processors required for this —instead an umbilical cable provides power and a network connection.

In its final version, the robot has 53 actuated degrees of freedom organized as follows:

• 7 in each arm
• 9 in each hand (3 for the thumb, 2 for the index, 2 for the middle finger, 1 for the coupled ring and little finger, 1 for the adduction/abduction)
• 6 in the head (3 for the neck and 3 for the cameras)
• 3 in the torso/waist
• 6 in each leg

The head has stereo cameras in a swivel mounting where eyes would be located on a human and microphones on the side. It also has lines of red LEDs representing mouth and eyes mounted behind the face panel for making facial expressions.

Since the first robots were constructed the design has undergone several revisions and improvements, for example smaller and more dexterous hands, and lighter, more robust legs with greater joint angles and which permit walking rather than just crawling.

Capabilities of iCub

The iCub has been demonstrated with capabilities to successfully perform the following tasks, among others:

• crawling, using visual guidance with optic marker on the floor
• archery, shooting arrows with a bow and learning to hit the center of the target
• facial expressions, allowing the iCub to express emotions
• force control, exploiting proximal force/torque sensors
• grasping small objects, such as balls, plastic bottles, etc.

iCubs in the world

There are about twenty iCubs in various laboratories mainly in Europe but also one in the USA. These were built by the RobotCub partners or other projects and form a small but lively community of scientists that use the iCub to study embodied cognition in artificial systems. Most of the financial support comes from the European Commission's Unit E5 or the Italian Institute of Technology (IIT) which is directed by Prof. Darwin Caldwell and Eng. Rosy Doronzo. The robots are constructed by the IIT and cost €200,000-250,000 each depending upon the version. The development and construction of ICub at the Italian Institute of Technology is part of an independent documentary film called Plug & Pray which was released in 2010.

External links

• Nosengo, Nicola (27 August 2009). "Robotics: The bot that plays ball". Nature 460 (7259): 1076–8. doi:10.1038/4601076a. PMID 19713909. http://www.robotcub.org/index.php/robotcub/content/download/1323/4602/file/nature_icub.pdf. Retrieved 2010-07-30.  - Nature article about the iCub.
• YouTube Channel - a YouTube channel about the iCub.
• iCub presentations - from the Humanoid robotics symposium 2010.
• IROS'10 - Videos and workshop on iCub research.