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Research paper : A methodology for improving reliability of complex systems (A. Katoh et al.)−203−Synthesiology - English edition Vol.3 No.3 (2010) The attributes of the cooperative behavior are determined based on the specifications related to the cooperative behavior and the properties which must be satisfied by the cooperative behavior. The attributes of the cooperative behavior can be categorized as follows:(1) There must be no lacks and variances in messages which are sent or recieved among components and processings related to the messages;(2) The timing of messages which are sent or recieved among components and processings related to the messages are correct.The model checking tool to be applied is selected according to the identified attributes. The representative types of model checking tools are finite automaton[17] Term 25 and timed automaton[18] Term 26 which is extended based on finite automaton. When verifying point (1), the model checking tool which corresponds to finite automaton is selected. SPIN[19] Term 27 is one of the representative model checking tools for finite automaton. When temporal limitations such as the timing are verified as in point (2), the model checking tool which corresponds to timed automaton is selected. Timed automaton is an extension of finite automaton. The model checking tool based on timed automaton can also verifiy point (1). UPPAAL[20] Term 28 is one of the representative model checking tools for timed automaton. Also, each component in the system behaves in parallel. Therefore, it is necessary to select the model checking tool which can model parallel systems. SPIN and UPPAAL can model the parallel systems.5 Application to industrial caseThere is recently a rapid advancement in functions of industrial robots[21] Term 29. Many industrial robots have a strong mechanical output due to the nature of their works; therefore safety of operators must be considered. The industrial robot is one of the systems which are appropriate for the application of this methodology. As of writing this paper, we are developing an industrial robot system for transporting irregularly shaped rigid-bodies, jointly with a manufacturer of industrial robots. We select the irregular-rigid-body-transport robot system as an industrial case study, and apply our methodology.Followings are descriptions of the irregular-rigid-body-transport robot system and results of applying this methodology.5.1 Irregular-rigid-body-transport robot systemThe irregular-rigid-body-transport robot system is an industrial robot system which engages in grasping, transporting, and placing of heavy rigid-bodies with irregular shapes and sizes. The characteristic of requirements for the irregular-rigid-body-transport robot system is that the system must have a strong autonomy in grasping and placing the irregular rigid-body. Although the area of grasping the irregular rigid-body is limited, the shape and size of the rigid-body, the position where the irregular rigid-body is grasped, and the direction of the irregular rigid-body are indefinite. The system must accurately determine the shape, size, and direction of the irregular rigid-body. Also, while the area in which the irregular rigid-body is placed is limited, the location in which the irregular rigid-body is placed within that area is indefinite. The system must accurately determine the location where other irregular rigid-bodies are not present, or the location with the lowest height in that area which is laid with other irregular rigid-bodies.In developing the irregular-rigid-body-transport robot system, system requirement analysis is conducted based on the system needs. The system specification is defined through system requirement analysis. This methodology is applied with the defined system specification as an input.5.2 Application of this methodologyIn this section, the specific applications of this methodology are described for architectural design method, bridge method, and model checking mentioned in chapter 4.5.2.1 Architectural design methodArchitectural designing is done using the system specification of the irregular-rigid-body-transport robot system as an input. By architectural designing, the specification of the irregular-rigid-body-transport robot system is decomposed into the specifications of the measurement subsystem, the robot subsystem, and the integrated control subsystem, as well as the interface specifications among the subsystemsTerm 30. Figure 10 shows the results of architectural designing for the irregular-rigid-body-transport robot system. In architectural designing, each subsystem is designed by assuming the subsystem componentsTerm 31 which compose the subsystem to make the most of COTS (commercial off the shelf)Term 32 products and existing technologies.The measurement subsystem is composed of a laser scanner to measure a three-dimensional shape, a vertical motion mechanism for the laser scanner, and a measurement control computer which controls them. The measurement subsystem measures the shape, size, position, and direction of the irregular rigid-body when grasping it. It also measures the unevenness of the area where the rigid-body is placed.The robot subsystem is composed of a robot arm, a robot hand, and controllers which control each subsystem component. It also has a teaching pendantTerm 33 for programming actions and emergency stop of the robot arm. The robot subsystem grasps, transports, places irregular rigid-bodies.The integrated control subsystem is composed of an

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