Masashi Murata

Collaborative movement of rescue robots for reliable and effective networking in disaster area

We investigated a collaboration scheme for rescue robots for reliable and effective operation of rescue systems using robots. The investigation focused on the collaborative movement of robots to maintain their wireless network. We propose classifying the robots into search robots and relay robots and using a behavior algorithm for their collaborative movement. According to the algorithm, search robots explore the disaster area and search for victims, whereas relay robots act as relay terminals within the network. Each robot classifies itself autonomously and repeatedly as the system operation progresses. We evaluated the performance of the victim detection system (a rescue system introduced in our previous paper) based on the proposed scheme by computer simulation. Its performance was improved compared with the case where every robot walked randomly in the disaster area and no classification occurred

Coordination of Rescue Robots for Real-Time Exploration Over Disaster Areas

A coordination procedure is proposed for a multi-robot rescue system that performs real-time exploration over disaster areas. Real-time exploration means that every robot exploring the area always has a communication path to human operators standing by a monitor station and that the communication path is configured by ad hoc wireless networking. The proposed system procedure consists of the autonomous classification of robots into search and relay types and behavior algorithms for each class of robot. Search robots explore the areas and relay robots act as relay terminals between search robots and monitor station. The rule of the classification and the behavior algorithm refer to the forwarding table of each robot constructed for ad hoc networking. Computer simulations are executed with the decision-theoretic approach as the exploration strategy of search robots.

Integrated operations of multi-robot rescue system with ad hoc networking

Integrated operations of a multi-robot rescue system are investigated. The system consists of a base station (BS) and autonomous mobile robots. A wireless ad hoc network connects all of them. Mobile robots coordinatedly explore a disaster area to detect victims and send their information to operators at the BS. Three related subjects are reviewed in this paper. First, autonomous chain network formations by rescue robots are investigated. The chain networks are essential for reconnaissance into distant spaces in disaster areas. Second, wireless QoS networks for multi-robot systems are investigated. This QoS scheme reserves the transmission bandwidth when a robot sends wideband signals to the BS through the chain network. Finally, wireless power supply networks for multi-robot systems are investigated. This scheme alleviates the problem of power source exhaustion of each robot and improves the reliability of multi-robot rescue systems.

Autonomous chain network formation by multi-robot rescue system with ad hoc networking

The autonomous chain network formation by multi-robot rescue system is investigated. Chain networks connecting a base station and rescue robots are essential to reconnoiter distant spaces in disaster areas. The chains must be formed to assure communications among them and must be transformed if the target of exploration changes. These formations must be executed by autonomous movements of robots from reliable viewpoints in rescue operations. As the basis of their movements, we adopt autonomous classification of robots into search robots and relay robots. They act according to the behavior algorithms of each class of robot to form chain network threading the path to the distant spaces. The rule of the classification and the behavior algorithm refer forwarding table of each robot constructed for ad hoc networking. The results of simulations show that chain networks are formed and transformed by rescue robots appropriately for their reconnaissance to distant spaces even though three spaces exist beyond different corridors stemming from the safety zone where base station is established.

Real-time exploration of a multi-robot rescue system in disaster areas

Abstract A system procedure is proposed for a multi-robot rescue system that performs real-time exploration over disaster areas. Real-time exploration means that every robot exploring the area always has a communication path to human operators standing by at a base station and that the communication path is configured by ad hoc wireless networking. Real-time exploration is essential in multi-robot systems for USAR (urban search and rescue) because operators must communicate with every robot to support the victim detection process and ad hoc networking is suitable to configure a communication path among obstacles. The proposed system procedure consists of the autonomous classification of robots into search and relay types and behavior algorithms for each class of robot. Search robots explore the areas and relay robots act as relay terminals between search robots and the base station. The rule of the classification and the behavior algorithm refer to the forwarding table of each robot constructed for ad hoc networking. The table construction is based on DSDV (destination-sequenced distance vector) routing that informs each robot of its topological position in the network and other essentials. Computer simulations are executed with a specific exploration strategy of search robots. The results show that a multi-robot rescue system can perform real-time exploration with the proposed system procedure and reduce exploration time in comparison with the case where the proposed scheme is not adopted. Graphical Abstract

Development of a surveillance cameras system in ad hoc network

This paper presents a surveillance cameras system that consists of only nodes without a server or a station using ad hoc network technology. Each node shares the picture that another node takes, in order to have the robustness against car thieves.

A broadcasting method based on RTS/CTS for an ad-hoc network

An ad-hoc network, which does not require a base station such as an access point, has a hidden node problem because nodes communicating in the same time cannot know each others communication status. In other hand, in the wireless infrastructure network the access point manages the communication with the node using RTS (Request to Send) and CTS (Clear to Send). However, in the broadcasting, we cannot use RTS/CTS method because the number of target nodes is not 1 but more than 2. In this paper, we propose a broadcasting method based on RTS/CTS to avoid this problem. Sender node selects the target node. And they communicate with each other. Neighbouring nodes can listen to these packets. Then sender node can broadcast its information to multi nodes. We use wireless nodes specified by IEEE 802.15.4 which is the physical layers specification. And our experiment results show the effective transmission.

A proposal for surveillance cameras system by Ad Hoc Network

We propose a new surveillance cameras system. This system uses nodes with cameras and without a camera. When taking a picture, it is transmitted to each node and stored by each node. If the crime occurs in the parking lot, it is useful for the calculation of the criminal by using the taken image. The newly feature of the system that we propose is to transmit the taken image to other nodes and to share image data with each node. Our monitoring system is different from a conventional monitoring system in the point that the file server is not needed. We construct a simple system.

An ad-hoc network routing protocol for a disaster scene

In recent years, ad-hoc network technology consisting of not access points and base stations but of wireless nodes has gained attention because the disaster scene requires quickly construction of the network. Usually the aim of routing protocol in ad-hoc network is to provide the stable network service. In order to maintain the network, node must communicate with each other in exchanging their routing tables. So the control packet does not include the information of an application layer. We propose the novel routing protocol for a disaster scene which includes the application information in the control packet. By using our proposed protocol, nodes can construct the routing table and send the nodes information to neighboring nodes at the same time. Then we investigate the tradeoff between relay hops and delay times. We show the experimental results for the real world.

A novel ad-hoc network routing protocol with an acceleration sensor

On an ad-hoc network which is consisted of movable nodes, the network topology is dynamic because each node is adaptive. So we must maintain the routing table in order to send a packet. In proactive routing protocols, each node exchanges their routing information in order to maintain the routing tables. In this type of protocol, we can send a packet quickly, but a lot of control packets are needed. So the battery life is short. On the other hand, in reactive routing protocols, a node starts making the routing table after receiving a packet sending request. So this protocol takes a lot of seconds to send a packet. In this paper, we focus on the cause that changes the routing table. Because we should update the routing table only when the node moves, we propose a novel routing protocol which has the acceleration information from the sensor. And a node exchanges the routing table only if it moves. We apply it to the surveillance camera system at a parking lot.