NAO ROBOT - ALDEBARAN ROBOTICS

Hardware Platform

NAO is a programmable, 57-cm tall humanoid robot with the following key components:

- Body with 25 degrees of freedom (DOF) whose key elements are electric motors and actuators

- Sensor network, including 2 cameras, 4 microphones, sonar rangefinder, 2 IR emitters and receivers, 1 inertial board, 9 tactile sensors, and 8 pressure sensors

- Various communication devices, including voice synthesizer, LED lights, and 2 high-fidelity speakers

- Intel ATOM 1,6ghz CPU (located in the head) that runs a Linux kernel and supports Aldebaran’s proprietary middleware (NAOqi)

- Second CPU (located in the torso)

- 27,6-watt-hour battery that provides NAO with 1.5 or more hours of autonomy, depending on usage

Motion

Omnidirectional walking:

NAO's walking uses a simple dynamic model (linear inverse pendulum) and quadratic programming. It is stabilized using feedback from joint sensors. This makes walking robust and resistant to small disturbances, and torso oscillations in the frontal and lateral planes are absorbed. NAO can walk on a variety of floor surfaces, such as carpeted, tiled, and wooden floors. NAO can transition between these surfaces while walking.

Whole body motion:

NAO's motion module is based on generalized inverse kinematics, which handles Cartesian coordinates, joint control, balance, redundancy, and task priority. This means that when asking NAO to extend its arm, it bends over because its arms and leg joints are taken into account. NAO will stop its movement to maintain balance.

Fall Manager:

The Fall Manager protects NAO when it falls. Its main function is to detect when NAO's center of mass (CoM) shifts outside the support polygon. The support polygon is determined by the position of the foot or feet in contact with the ground. When a fall is detected, all motion tasks are killed and, depending on the direction, NAO's arms assume protective positioning, the CoM is lowered, and robot stiffness is reduced to zero.

Vision

NAO has two cameras and can track, learn, and recognize images and faces.

NAO sees using two 920p cameras, which can capture up to 30 images per second.

The first camera, located on NAO’s forehead, scans the horizon, while the second located at mouth level scans the immediate surroundings.

The software lets you recover photos and video streams of what NAO sees. But eyes are only useful if you can interpret what you see.

That’s why NAO contains a set of algorithms for detecting and recognizing faces and shapes. NAO can recognize who is talking to it or find a ball or, eventually, more complex objects.

These algorithms have been specially developed, with constant attention to using a minimum of processor resources.

Furthermore, NAO’s SDK lets you develop your own modules to interface with OpenCV (the Open Source Computer Vision library originally developed by Intel).

Since you can execute modules on NAO or transfer them to a PC connected to NAO, you can easily use the OpenCV display functions to develop and test your algorithms with image feedback.

Tactile Sensors:

Besides cameras and microphones, NAO is fitted with capacitive sensors positioned on top of its head in three sections and on its hands.

You can therefore give NAO information through touch: pressing once to tell it shut down, for example, or using the sensors as a series of buttons to trigger an associated action.

The system comes with LED lights that indicate the type of contact. You can also program complex sequences.

Sonar Rangefinders:

NAO is equipped with two sonar channels: two transmitters and two receivers.

They allow NAO to estimate the distances to obstacles in its environment. The detection range is 0–70 cm.

Less than 15 cm, there is no distance information; NAO only knows that an object is present.