Page 444 - Mechatronics for Safety, Security and Dependability in a New Era

Ch86-I044963.fm Page 428 Tuesday, August 1, 2006 5:29 PM
Ch86-I044963.fm
428
428 Page 428 Tuesday, August 1, 2006 5:29 PM
the malfunctioning module need to be replaced), reusability (the same modules can be used in
different robots), stability and reliability (reused and thus tested modules tend to be stable and thus
more reliable), and faster design (system development can be easily divided between development
teams). Several modular hardware solutions exist and have been used for building mechatronic
systems. For example OOPic (2004) has a board that allows attachment of different kind of sensors
and actuators on the board to build a controller for a robot. The number of sensors and actuators per
board is very limited, however.

In our approach, called the Atomi concept, small- size embedded objects have been developed to a
reach the high level of modularity in the embedded system. Atomi boards are mainly intended for
fast prototyping and the creation of easy, high-level embedded systems. The purpose of Atomis is to
lower the threshold of creating embedded systems by making the creation of embedded systems
both affordable and as easy as possible, so that the building does not require much time or expertise
in electronics. The Atomi boards are described in more detail by Vallius et al. (2004). Qutie robot
provides a challenging and complex test platform for Atomi boards.

THE ROBOT

Qutie is a mobile robot designed to perform a variety tasks in common environments, such as
homes or public places, in interaction with humans and other robots. Further, the robot must have
versatile capabilities for interacting with people. The main features of Qutie are a round shape, a
belly screen, and furry skin. As the robot is used for research of human-robot interaction, it should
be easily modifiable, so that the features of the robot could be changed based on the tests. An
overall view of system components is shown in Figure 1. The robot has two computers, a main
computer located on the base and a small PC 104 computer on the neck and head unit. The parts of
the robot are independent and can be separated. The minimal connections between the body of the
robot and the neck head mechanism contain only the power and ground lines, and the Ethernet
connection between the computers.
The operation of the robot's head and neck mechanism of the robot is shown on Figure 2. The neck
has four degrees of freedom, three rotations, and one translation of elevation along the z axis. The
linear resolution of each motor's step movement along a moving linear axis is 0.024 mm, and range
of operation is limited to 100 mm. The linear motors A, B, and C have flexible joints at the top and
the bottom as rotation requires the motors body to rotate. Through the capabilities of its neck, robot
can change the orientation of the head camera. In addition, the robot can show "emotions" when
interacting with humans. The neck mechanism control Atomi boards are connected to the head
computer through a USB connection. The head computer operates all the functions of the head and
neck unit, and it is a stand-alone unit requiring only 5 V power from the robots base. To reduce the
power requirements, the hard disc of the computer has been replaced by a Compact Flash card
drive.

Figure 1. Hardware modules of Qutie robot