IEEE/ASME TRANSACTIONS ON MECHATRONICS, VOL. 9, NO. 3, SEPTEMBER 2004 535 Cooperation of Distributed Intelligent Sensors in Intelligent Environment Joo-Ho Lee, Member, IEEE, Kazuyuki Morioka, Student Member, IEEE, Noriaki Ando, Member, IEEE, and Hideki Hashimoto, Member, IEEE Abstract—We propose an architecture of intelligent space based on distributed intelligent sensors. Intelligent space is an environ- mental system able to support humans in informative and phys- ical ways. Since an intelligent space should adapt to the various sizes and shapes of an environment, an architecture based on dis- tributed intelligent sensors is designed. The proposed architecture satisfies not only scalability but also reconfigurability, modularity, easy maintenance, and affinity problems in building an intelligent space. Intelligent sensors are distributed among a space and they provide functions based on position information. According to the particular situation, cooperation among intelligent sensors or co- operation among function modules in the intelligent sensors are performed. Selected demonstrations are described in the paper. Index Terms—Distributed system, intelligent space, ubiquitous computing. I. INTRODUCTION I NTELLIGENT space was proposed by Lee [15] of the Uni- versity of Tokyo, Tokyo, Japan as an environmental system able to support humans in informative and physical ways. Most intelligent systems interact with humans in a passive space; but in an intelligent space, being a space that contains human and ar- tificial systems, the space itself is an intelligent system. Human and artificial systems become clients of the intelligent space and simultaneously the artificial systems become agents of the in- telligent space. Since the whole space is an intelligent system, intelligent space, as a spatial system, is able to easily monitor and provide services to clients. Specific tasks, which cannot be achieved by just the intelligent space, are accomplished by uti- lizing its clients. For example, an intelligent space utilizes com- puter monitors to provide information to humans, and robots are utilized to provide physical services to them as physical agents. If necessary, robots as well as humans are supported by an intel- ligent space. When a robot lacks the sensors to navigate around an intelligent space, the robot is treated as a client of the intel- ligent space and the information lacked is provided to the robot by the intelligent space. An intelligent space has two roles in respect to a robot working in it. One is the enlargement of ability, the other is resource sharing. Generally an intelligent robot has its own Manuscript received January 31, 2004; revised June 21, 2004. J.-H. Lee is with Department of Information and Communication Science, Ritsumeikan University, 525-8577 Shiga, Japan (e-mail: leejooho@ieee.org). K. Morioka is with Department of Electrical Engineering, University of Tokyo, 153-8505 Tokyo, Japan (e-mail: morioka@hlab.iis.u-tokyo.ac.jp). N. Ando is with AIST, 305-8561 Tsukuba, Japan (e-mail: n-ando@aist.go.jp). H. Hashimoto is with the Institute of Industrial Science, University of Tokyo, 153-8505 Tokyo, Japan (e-mail: hashimoto@iiis.u-tokyo.ac.jp). Digital Object Identifier 10.1109/TMECH.2004.834655 sensors and it is designed to move without help from outside. However, even an intelligent robot has limitation of ability; for example, when a person in different room needs the help of the robot, the robot has difficulty ascertaining that there is a request. Even though it has good sensors, this kind of problem cannot be overcome. An intelligent space has a role as an extended sensor for the robot and enhances the ability of the robot to receive the request form a distant place. Resource sharing is valid when more than one robot uses the resources of an intelligent space; and robots can decrease their common resources such as sensors to localize, sensors to detect target objects, devices to interact with humans, etc. However, an intelligent space does not aim to get rid of sensors or autonomy from robots; rather, it supports a robot by providing the resources it lacks to act as a normal robot, while helping a robot with good resources to act as an even better robot [17]. The ultimate goal of our intelligent space project is to accom- plish an environment that comprehends human intentions and satisfies them. Such a system appears difficult to achieve, since a many functions must be prepared and human-like intelligence is required. Though such a complete system cannot be imme- diately achieved, we are convinced that a useful system can be achieved utilizing current technology assisted by proper system integration. This paper aims to propose an architecture of intelligent space based on distributed intelligent sensors. Since an in- telligent space is a spatial system, its size and shape are not predetermined or restricted, intelligent sensors are therefore proper elements with which to build such kinds of system. If sensors are directly connected to a centralized system and the system processes all data for the sensors, the sensor cannot really adapt to alternations in target environments. Intelligent sensors, however, differ from conventional ones in their ability to process large amounts of data close to the source, and in their ability to communicate bi-directionally. These features help to build intelligent spaces in various shapes and sizes. We will describe a space that is watched by many distributed intelligent sensors and the sensors cooperate with each other in this intelligent space. By cooperation among intelligent sen- sors, the service of an intelligent space can be provided globally and seamlessly in a space. An intelligent sensor in an intelligent space watches a fixed local area and it provides position based data continuously for high level and complex functions. In Section II, intelligent space and related works are intro- duced. An architecture for intelligent sensors for use in intel- ligent spaces is proposed and basic functions are described in Section III. Section IV shows how intelligent sensors cooperate 1083-4435/04$20.00 © 2004 IEEE