We propose information assistance for a victim search system in a rescue activity. We have developed an intelligent data carrier system (IDC) that provides the environment with information storage, sensing, and processing functionality. Each IDC unit has its own CPU, memory and radio communication module. We have incorporated the auditory functionality into IDC units and applied them to rescue activity support. IDC units attached in buildings are activated by broadcast of a wake-up signal, and then they repeat calling to victims and recording their answers independently. Rescue parties perform effectively by seeking records of victims. We have also built an autonomous dispatch system of autonomous robots based on the information obtained by the IDC system.

We propose a behavior learning method of a mobile robot using visual information. The proposed system consists of two networks for the state expression and the behavior generation. The state expression network, which is based on self-organizing algorithm, categorizes the robot's states. Also, the behavior generation network acquires the robot's behaviors using the output of the state expression network. Here, for training the behavior generation network, we utilize the actor-critic method as a kind of unsupervised learning scheme. We report some experimental results using the mobile robot in real environment. The mobile robot generates adaptive behaviors utilizing visual information.

This paper discusses the problems in teleoperation systems for mobile robots and the use of a virtual world in these systems. In order to achieve smooth operation of the mobile robot via the communication link, we should consider the delays in data transfer. To compensate the incomplete data sets, virtual images can be generated by computer graphics when the information of the working environment can be acquired beforehand. We construct a virtual world teleoperation system. The performance of the system is examined through experiments with an actual mobile robot. It is shown that the virtual robot can be operated by a human operator in almost the same manner as a teleoperated real robot.

We have proposed the collision avoidance methods in a multirobot system based on the information exchanged by the "LOCISS: Locally Communicable Infrared Sensory System", which is developed by the authors. One of the problems in the LOCISS based methods is that the number of situations which should be considered increases very much when the number of the robots and stationary obstacles in the working environment increases. In order to reduce the required computational power and memory capacity for such a large number of situations, we propose, in this paper, a multilayered reinforcement learning scheme to acquire appropriate collision avoidance behaviors. The feasibility and the performance of the proposed scheme is examined through the experiment using actual mobile robots.

This paper presents a novel concept of self-organizing collective robots with morphogenesis in a vertical plane. It is potentially applicable to autonomous mobile robots. For physical reconfiguration of a swarm of robots against gravity, new types of mechanisms and control strategies are proposed and demonstrated. Prototype robots have been fabricated in order to confirm the basic feasibility of the mechanisms. Each robot is composed of a body and a pair of arms. The body can be regarded as a cube with edge length of 90 mm, and is equipped with permanent magnets for bonding with another robot. The arms change the bonding configuration by rotating and sliding motions. As for the control strategies, we proposed the algorithms which can locally generate specific global formations of robots, with minimum interactions between neighboring robots. The overall scheme is similar to cellular automata. The control algorithms proposed have been tested by simulations.

We propose an algorithm for unforeseen obstacle avoidance by an autonomous sweeping robot. Sweeping means a motion that a robot covers a 2-dimensional area. When a mobile robot finds an unforeseen obstacle, it not only has to avoid collision but also sweep whole area including around the obstacle. In the proposed algorithm, a robot determines local area where path for sweeping should be arranged according to its limited sensing ability. By connecting the paths inside and outside the local area, the robot obtains a new total path. The local path re-planning saves heavy calculation to generate whole path again at online.

In this paper, we discuss autonomous navigation in multirobot environment based on local communication. To carry out cooperative tasks using multiple autonomous robots, navigation systems should be implemented to the robots because mutual alignment of their positions and collision avoidance to each other become important. Therefore, it seems a collision avoidance and a self-localization are indispensable as elemental techniques for the navigation. Although these techniques need to recognize situation of robots surrounding environment, conventional devices to acquire information around them can not work sufficiently in such environment. For this problem, we propose techniques based on the local communication and the navigation system by combining them for multirobot environment. It is shown that robots can arrive their goal precisely without collision among them through proposed navigation systems.

We discuss adaptive behavior acquisition for collision avoidance among multiple autonomous mobile robots which are equipped with the locally communicable infrared sensory system (LOCISS). The LOCISS is a local sensing device for collision avoidance by which robots can detect other robots and obstacles and discriminate them by exchanging relevant information. We (1996) reported previously a collision avoidance method between two robots based on the predetermined rules using LOCISS. It is, however, difficult to realize collision avoidance among three or more robots by the predetermined rules only because situations around the robots become more complicated as the number of robots increases. Thus, it is desirable for the robots to have an adaptive capability for acquisition of the behaviors to avoid collision with other robots and obstacles. To acquire the adaptive behavior, the reinforcement learning is introduced in this paper. It is shown that appropriate behaviors for collision avoidance can be successfully acquired through the proposed learning process.

Collision avoidance is an essential problem for applications of multiple mobile robots. The authors have proposed new sensor system called LOCISS (Locally Communicable Infrared Sensory System) to detect robots and obstacles using infrared local communication. Robots mounting LOCISS can exchange useful information for collision avoidance such as speed and moving direction. In this paper, a set of rules for collision avoidance among multiple autonomous mobile robots using LOCISS is proposed. Each robot mutually carries out collision avoidance using the proposed rule. The validity of this set of rules is shown through a series of experiments using mobile robots.

A concept of mutual transportation by cooperative multiple mobile robots is proposed in this paper, which enables robots to process complicated or heavy-duty tasks, and overcome the large obstruction in an environment. A method of mutual transportation utilizing forklift mechanisms is introduced with discussion on the lifting process and moving process. Cooperative mobile robots including a holonomic omni-directional platform and a forklift mechanism are developed. Finally, as an example of applications of mutual transportation, step-climbing motion is presented, and the motion realized by the developed mobile robots is shown.

This paper proposes a new strategy for knowledge sharing among multiple autonomous mobile robots using newly developed intelligent data carriers (IDCs) to make the multi-robot system more flexible and robust against complex environmental conditions and, to reduce the amount of global communication for mutual exchange of information which is useful locally in a limited area. The IDC is an immobile but portable device (data carrier) for information storage and management with a unique mushroom-like structure to be easily handled by a forklift mechanism which can be mounted on actual mobile robots. A robot can place a unit at a specific location in its working environment and write locally relevant knowledge into the unit. Other robots can share the knowledge which should indicate the existence of specific instruments, objects or topographies, e.g., dead ends, drop-offs, steps, etc., by reading from the placed IDC units. The handling method of the IDC unit is examined through the experiment using an omni-directional mobile robot. It is shown that the robot succeeded in placing the unit at an appropriate location to share the information indicating that a dead end exists.

In this paper, we propose an off-line planning algorithm for cooperative tasks of multiple mobile robots. Sweeping means a motion that a robot covers a 2-dimensional area by its effector. Sweeping of a whole work area is fundamental and essential task of mobile robots. It is more effective if a robot can move an obstacle during a sweeping task as if we clean our room with relocating chairs. We can also consider that this is the simplest task which includes both point-to-point motion and sweeping. We model sweeping and relocation, and propose an algorithm to find appropriate path for robot and way of relocation of each obstacle. We apply the LT graph to solve the problem, which describes both motions of robots and blockades by obstacles in path-time space. We verify the efficiency of the algorithm through simulations and experiments.

A new driving mechanism for holonomic omnidirectional mobile robots is designed, which enables 3 DOF motion control by three correspondent actuators in a decoupled manner with no redundancy. A prototype of the omnidirectional mobile robot with the driving mechanism is developed including a parallel link suspension mechanism. The kinematics of the omnidirectional mobile robot is also analyzed, and simulation for velocity control of the robot is performed by a method for velocity modulation with interpolation to achieve the given target position and velocity.

Distributed autonomous robotic systems which are composed of multiple robotic agents have been attracted the attention of many researchers as a new strategy for flexible and robust robotic systems. For cooperative multiple mobile robots in distributed autonomous robotic systems, recognition of the dynamic environment is required. In this paper, a new sensory system with local communication functionality is developed utilizing infra-red devices. Based on the discussion on sensing and communication for cooperative multiple mobile robots, requirements for the sensory system are derived. Then, the infra-red sensory system is designed and developed taking account of the required function. This system enables not only detection of collisions against obstacles or other robots but also local communication between robots. This system can also detect interference of plural infra-red signals. Finally the developed system as introduced, and its performance obtained as a results of experiments is shown.

This paper first discusses the relation between the human operator and the decentralized autonomous robotic system. The operator relates himself to the system loosely in the decentralized autonomous system. The authors position the operator as a problem solver and a monitor of the system. The human operator is regarded as an agent in the decentralized autonomous robotic system. Then strategies of communication between the human operator and agents are discussed. The authors propose explicit and implicit communication strategies to monitor the system, and several monitoring methods to implement them: time-based and event-based monitoring for explicit communication and eavesdropping messages for implicit communication. The authors compare the monitoring methods in order to ascertain how much information the human operator can gather in each method using simulation. Finally, the characteristics of each monitoring method are analyzed.

As a flexible and robust intelligent robot system, we have been developing an autonomous and decentralized robot system called ACTRESS, which is composed of multiple robotic agents who have various kinds of functionalities. In order to achieve a given mission in multirobot environment, cooperative behaviors by autonomous agents are essential. In this paper, we focus on the case that multiple robots execute a task cooperatively with functional complement, especially for sensing function. We discuss cooperation of multiple robots using communication in a multi-agent robotic system, and propose a method of functional complement by multiple agents, including group organization and cooperative motion control. Finally, we show the experimental result to verify the proposed method.>

The paper describes the human interface system in the autonomous and decentralized multi-agent robotic system ACTRESS. The human interface system coordinates the interaction between the human operator and robotic agents, monitors system's activities and presents them do the operator. The operator can send commands to individual robotic agents or a group of agents through the human interface. He can also intervene in the system based on monitored system status if and when necessary. The human interface also acts as a window through which the robotic agents contact the operator for judgment and advice. The paper presents the architecture of the human interface system. The architecture was designed so as to allow the operator to interact with the system through consistent interface in the real environment and in the simulator environment, in which robotic agents' programs are developed.>

As a flexible and robust intelligent robot system, we have been developing an autonomous and decentralized robot system called ACTRESS, which is composed of multiple robotic agents. In this paper, introducing an idea of cooperative action with group organization and a strategy for cooperative task processing using communication, a method for team organization by efficient negotiation is presented. The efficient negotiation is realized by a newly developed communication functionality called groupcast and a learning mechanism utilizing historical records on past negotiation. The negotiation procedures for team organization are implemented, and as a result of simulation experiments, the efficiency of the learning mechanism is verified.>

The authors describe the basic design of Fun-ARM, and discuss the strategy of the fault tolerance on distributed manipulator. The fault model is described, and assumptions in the system are discussed. The methods to realize fault tolerance are proposed, including methods for fault-detection, fault-localization and fault-containment.

This paper addresses a method for synchronizing motion by multiple autonomous mobile robots using radio communication. The autonomous and decentralized robot system, ACTRESS, is a multi-agent robotic system including multiple autonomous mobile robots. The autonomous mobile robots are developed so as not only to act individually, but also to cooperate with the other robots if they cannot accomplish the task alone. The synchronized motion is sometimes required to execute such cooperative tasks. Every agent of ACTRESS is equipped with the communication system, which enables a message passing between any robotic agents. The prototype ACTRESS system is introduced, and cooperation among multiple robotic agents is discussed. A method for synchronization using the communication system is proposed. The method is applied to the prototype system, and side-by-side motion on the actual mobile robots is implemented as a example of synchronized motion.

An autonomous and decentralized system called ACTRESS (ACTor based Robot and Equipment Synthetic System) is being under development as an intelligent robot system which can execute high level tasks. ACTRESS is composed of multiple robotic agents. Each robotic agent is called robotor. A robotor may be a robot, a computing system and any other equip- ments. While researching in this field, many research issues need to have solutions, such issues may include, the communication among the agents and protocols, cooperation among a group of agents, describing the tasks to be executed, multi-agent motion planning, multi-agent task planning, task description, human interface role, solving deadlocks ... etc. The aim of this paper is to develop a simulation environment for an autonomous and decentralized multi-agent robotic system. For this purpose, it is neces- sary to simulate and analyze the main functions of each agent, design and analysis of the actions to be carried out by each agent, analyzing their real time behavior with a variety of situations considering their environ- ment and the treatment of unexpected events. Also, it is aecessary to find out an efficient strategy to realize effective means for the agents to form a cooperating manner that support task execution and problem solv- ing. In parallel with the mentioned purposes the ACTRESS structure is simulated as functions and behavior using the developed simulation environment. This simulation includes a group of mobile robots, human interface and global environment manager. Then, software integration that deal with various aspect of the overall problem is developed. Different experi- ments are performed to analyze the performance of each individual robotor and the overall system.

An autonomous and decentralized robot system, ACTRESS, is being developed as an intelligent robot system which can execute high level tasks. The concept of ACTRESS is introduced, and the communication framework between robotic agents that compose the robot system is proposed. Taking a task of pushing objects by multiple mobile robots in a certain working environment as a case study of ACTRESS, the strategy for organizing the robot system is discussed, and the required functions for the robot system are introduced. The optimal distribution of the functions is designed based on communication evaluation. An algorithm for static path planning and a strategy for dynamic path planning are proposed.>

An autonomous and decentralized robot system, ACTRESS, is being developed as an intelligent robot system which is composed of multiple robotic agents. The basic concept and strategy for path planning in a dynamically changing environment with multiple autonomous mobile robots are introduced. Collision avoidance with dynamic path planning according to the complexity of the situations is also discussed. A method for collision avoidance based on rules and negotiation by communication is presented. Finally, this method is applied to a developed prototype system consisting of two mobile robots, and the result of experiments operating on real robots is given.>

Deals with a kind of cellular robotic system (CEBOT), called self organizing manipulator system. In this system the configuration of the manipulator can be changed according to the given task. The authors use two manipulators to assemble, disassemble, and reassemble cellular universal manipulator by cooperation work. When a simple task is given, the system can analyze the task and generate the structure of the cellular manipulator. The assembling work was divided into modular subtasks, and then the system generate the macro command based on the database. The order of subtask and the collision avoidance are considered for planning the cooperation work by using the collision database which was calculated before hand. They show the algorithm for calculation the collision database and for planning the cooperation work. The results of the simulation and the experiment are shown.>