This paper reports an overview of a mobile robot “Phoenix-L” for decommissioning tasks and its evaluation tests. Phoenix-L consists of a vehicle mechanism “PHexa-L” and an arm mechanism “PArm-L”. PHexa-L is a six-wheeled vehicle that can control ground pressure by pneumatic control, and is easy to decontaminate and turn in a small space. The proposed differential wheel mechanism also enables to run over rough terrain. PArm-L has a coupled-drive structure in which all of the motor and sensors to control both the arm and the gripper are arranged in the base, and the entire structure is composed of only mechanical elements. Thus, it has high radiation resistance. Various tests using the prototype have confirmed the effectiveness of contact pressure control of the wheels, the ability to run over rough terrain, and the feasibility of light tasks.

橋梁点検は，点検技術者による近接目視点検を行うため損傷確認，計測，記録，写真撮影等の多くの作業を高所の限られた作業空間で行うことが一般的で，危険を伴う現場作業である．そのため点検技術者の作業負担低減とより安全で確実な点検を実現するため，ロボット化が有効と考えられている．ロボット化には特にドローンを利用する方式が多く試みられているが，我々は，点検者による現地の安全な場所での損傷確認と，計測，記録，撮影をロボットで実現することを目標として，ワイヤ支持方式を選択した．その上で対象となる橋梁の特性を分析して仕様を定め，従来の手法では課題となっている設置や，狭隘部への進入，広い適用範囲などを実現し，実橋実証実験で実用性を立証した．

This paper presents SH wave scattering by a frozen porous inclusion embedded in fluid-saturated porous media. We propose two computational methods, wave function expansion (WFE) and boundary element method (BEM), for wave scattering analyses. In WFE formulation, the components of displacement and stress are expressed by the superposition of the Bessel functions. The unknown coefficients in the expression are obtained via boundary conditions. On the other hand, in BEM formulation, boundary values of the frozen porous media are expressed by generalized displacement and traction. The generalized displacement consists of displacement components of the solid skeleton and the ice matrix, and the generalized traction is composed of the traction components of the two solid phases. Several numerical examples provide the validity of the proposed methods and the properties of the scattered waves. The discussion of the scattering properties focuses on the effects of ice saturation parameter, frequency of harmonic incident wave, the incident angle of the harmonic wave and the shape of the inclusion.

地震防災意識の涵養のためには，避難訓練に加え，地震を体感できる教育用の装置を利用することが有用である．我々はこれまでに人が乗ることができる自走式地震動発生装置を開発してきた経緯があるが，今回の開発では，振動実験を簡単に行うことや，建物の固有振動数の違いによる揺れの視覚化などを目指した新しい可搬型地震動シミュレータを開発した．本機では従来の装置よりも軽い積載質量10kg程度を目標として設計することで，小型軽量化を行うとともに，従来では実現が難しかった3～10Hzの周波数領域での水平2成分の振動を生成させるものである．今回はその実現を目指し，床面のグリップ力を強化するブレード型オムニホイル車輪と，全方向に機敏に動くために車輪を捩じり放射に配置した全方向加速度発生機構という2つの新しいメカニズムを採用した．本論文では，その設計要件と機能，試作機の構成，実験結果を報告する．

In this paper, we described the principle, design prototype and evaluation of of 3-dimensional gravity compensation mechanism for human coexistence robot. In this mechanism, it is possible to realize 3-dimensional gravity compensation by rotating the entire pantograph mechanism at the root and arranging actuators as counterweights so as to balance moments of all joints. We derive the relationship such as the link length and the center of gravity position to realize this. In addition, by constructing a mechanism that adds compensation force using wires, the entire arm is made as compact as possible. From the joint torque simulation and experiment of the prototype arm, it was confirmed that the arm can be driven with joint torque of 15% to 25% with respect to the arm without compensation meshanism. In addition, it was found that the effect of reducing the torque supporting the arm's own weight was larger than the influence of the increase of the moment of inertia by counterweight.

Long-reach robotic manipulators are expected to be used in the space where humans cannot work such as nuclear power plant disaster areas. We suggested a coupled tendon-driven articulated manipulator ‘3D CT-Arm’ and developed a preliminary prototype ‘Mini 3D CT-Arm’ whose arm had 2.4 m length and 0.3 m width. In order to consider developing ‘3D CT-Arm’ deeply, we discussed tension transfer efficiency of a tendon through pulleys, the arrangement of the maximum number of reels in a limited space and the tip positioning accuracy. Through many transfer efficiency experiments, we conclude that tension transfer efficiency of ‘3D CT-Arm’ can reach over 88 % in the worst case. We investigated non-interfering reels’ arrangement in the base by full search in cases of up to 10 reels. In all simulations, V-shaped or W-shaped arrangement can support the most reels in a limited space. Therefore, we conclude this is the most optimal reels’ arrangement. Finally, we carried out the positioning accuracy experiment with ‘Mini 3D CT-Arm’ via motion capture system. Although the tip position had a 2 to 41 mm error between the desired value and the measured value by potentiometer, a 29 to 95 mm error between the desired value and the measured value was measured by motion capture system.

Most of the long-reach inspection devices developed so far have a limitation in the reduction of their diameter when their length is increased. This limitation is due to the technology used to provide the actuation to the system. The use of water-jet as propulsion source is promising to be a solution for this problem. Currently different devices use water-jet as propulsion. However, none of these systems have been designed for small-scale nor have a straightforward control. Therefore, in this paper, we discuss the development of a long-reach water-jet probe aimed to be used in Fukushima Daiichi Nuclear Power Plant. The main elements that define this probe are three high-pressure pumps at the base, three hoses whose water flow is controlled for maneuvering the device, an Inertial Measurement Unit to acquire the attitude of the tip, and a joystick that allows the user the control of the whole device. Moreover, its design allows it to move in different kind of environments and generate three-dimensional motion. Besides the experimentation developed to characterize its behavior, the system was tested in different environments; such as on the ground, in the air and inside the water; showing the best control in aquatic environments.

Existing boundary element methods (BEMs) have been proven to be efficient numerical techniques particularly in modeling wave propagation problems but still remain limitations in solving large-scale problems. The main disadvantages may be caused by several problems, including high cost and large amount of computer memory for the computation. A time-domain BEM in which a collocation method is used for the time discretization also shows numerical instability for small CFL (Courant–Friedrichs–Lewy) number. In this work, we propose a new three-dimensional (3-D) approach for solving transient elastic wave propagation problems of large-scale spherical and spheroidal cavities by the convolution quadrature BEM accelerated by fast multipole method (FMM) using an implicit Runge–Kutta scheme (in abbreviation, we name it as IRK-based CQ-FMBEM). Two special techniques pertaining to the FMM including the scaling of modified spherical Bessel functions and the truncation method are used to enhance the efficiency and stability of our proposed method. This approach is found to be particularly suitable for 3-D large-scale problems as its high accuracy, stability of time-marching process, and computational efficiency. These properties are subsequently illustrated through numerical examples dealing with large-scale wave problems of 3-D single spherical and spheroidal cavities and multiple equally and irregularly spherical cavities. The accuracy of the present formulation is verified by comparing the obtained results with available reference solutions in the literature. Some numerical aspects of time increments, sizes and topological shapes of cavities, and their influences on the deformations and the waveforms are investigated. Also, detailed investigation of the computational efficiency of our proposed method, such as CPU time, required memory, etc. is presented. All the implementation tasks are carried out using the Tokyo Tech. supercomputer which is called TSUBAME 2.5 [42].

The movable range of tethered teleoperated robot which has no cable reels is quite limitted since the cable generate large friction force with ground and obstacles. In this research, we will propose a novel system which consists of many thruster module, and supports teleoperated robot pulling its cable. As a prototype of this system, we developed ”Crank Tether Thruster”(CTT) modules which consist of crank wheel mechanism, tension sensors, and an accelerometer. As a result of comparative experiment pulling cable with / without CCT modules, it is confirmed that cable pulling tension became lower in both straight corridor and edge corner.

An amphibious all terrain mobile robot is required for disaster response tasks. In this paper, we propose “R-Crank”, which has a simple four wheels driving configuration with crank links, connecting to ipsilateral front and rear wheels so as to form parallel four-bar linkage systems. The crank links act as legs because their trajectory with respect to the ground become trochoid curve, which is commonly used as leg trajectories for a legged robot. These links achieve high terrain adaptability while maintaining simple structure of the wheeled robot. We developed a prototype model and carried out basic experiments. The robot achieved to climb 0.3 m of a step(76.9% of the wheel diameter), stairs and a snowy slope. In addition, we propose amphibious structure of crank links by installing multiple rigid paddles. The propulsive force generated by the crank links was measured and empirically derived the optimum parameters by using a small-sized experimental apparatus. Finally the robot equipped with the amphibious crank links achieved propulsion on water at 0.13 m/s. We also verified that the robot achieved going up and into water through stairs.

Long-reach robots offer good performance developing tasks in areas where the access is difficult or dangerous. Due to their multiple degrees of freedom, they are able to adapt easily to different environments. These robots base their locomotion to two different elements: tendon cables or fluid pressure elements. Normally these robots are divided in sections and each section has its independent degrees of freedom. Therefore, if the length of the robot increases, the number of sections increases as well. This also means an increment in the diameter for each section and a more complex control for the whole system. In this paper we introduce the concept of a novel water-jet long-reach robot, which allows increasing the length of the robot without affect its number of elements, control complexity and diameter. Due to its characteristics, it is possible to use this robot in different environments, confined or opened spaces. We test the performance of the first prototype in different scenarios in order to validate our concept.

In places such as nuclear power plant disaster area, which it is difficult for human workers to enter, robots are required to scout those places instead of human workers. In this paper, we present a mobile manipulator HELIOS X for a nuclear plant decommissioning task. Firstly, we address demands and specifications for the robot, considering the mission of reconnaissance. Then we outline the system of the robot, mainly focusing on the following mechanism:“Crank Wheel”, “ Main Arm ”,“ Sphere Link Wrist ”,“ Camera Arm ”,“ Control System ”and“ System architecture ”. Especially, we installed 3 degree of freedom“ Camera Arm ”on the“ Main Arm ”, in order to improve functionality of remote control system. This enables the operator to monitor both the gripper and its overall view of the robot.“ Camera Arm ” helps the operator to recognize the distance from an object to the gripper, because the operator can interactively move the viewpoint of the camera, and monitor from another camera angle without changing the gripper’s position. We confirmed the basic functionality of mobile base,“ Main Arm ”and“ Camera Arm ”through hardware experiments. We also demonstrated that HELIOS X could pass through the pull-to-open door with a substantial closing force when the operator watched camera view only.

Remotely operated mobile robots are demanded in many disaster fields, such as Nuclear/Biological/Chemical(NBC) terrorist attacks, earthquake and tsunami, and even in minefields, to assure safety for the human workers. It is a common choice to use commercial game controllers with joysticks and buttons to control such robots, but many complex manipulation tasks require much higher operability only achieved by Master-Slave systems. In this research, we propose a new bilateral remote controller called “Armrest Joystick” which has Master-Slave function and also presents high operability characteristics. It consists of : (i) a 3DOF position arm mechanism which is attached to a foldable portable chair, and the foremost link part acts as an armrest to support the operator's arm; (ii) a 3DOF wrist posture mechanism whose rotation centers were carefully designed to match the human hand; (iii) a gripper mechanism which has good follow-up performance for fingers. Furthermore, all 7 joints (axes) are equipped with electrical motors and are actuated to give the operator Force Feedback. In this paper, we report the basic concept and explain in detail the mechanism design of the Armrest Joystick, and then show the experiments to check basic performance, specially about the armrest, and which we conducted using an actual rescue robot as “slave”. The results verify the validity of the mechanical design, and show that the Armrest Joystick can be more intuitively used than the former commercial game controllers.

After the incident in Fukushima nuclear plant, the access to several critical areas was damaged. Thus, the monitoring of them turned difficult. In order to keep tracking the status of these areas, it has been proposed to insert sensors through piping that is located nearby the element of interest. However, these pipelines have many restriction, like small diameter, changes of direction, elements that block access, etc. and none of the existing technologies have the capability of going through the piping while carrying the required sensors. In this paper we report a proposal of a new system, whose propulsion is based on water-jet. This device shows good possibilities to fulfill the requirements of carrying out the desired task. The design of this proposal aims to solve the limitations observed in the experiments done with a current technology, which are also described briefly. Basic tests done with the prototype developed are shown as well.

In this paper, we discuss development of a sprawling-type quadruped robot named TITAN-XIII which is capable of high speed and energy efficient walking. We consider a sprawling-type quadruped robot is practical, because of its high stability which comes from the large supporting leg polygon and the low center of gravity. However in previous researches, the speed and the energy efficiency of a sprawling-type quadruped robot is lower than a mammal-type quadruped robot. Since cost of transport (COT) can be reduced by increase of walking velocity, we decided to design a fast walking sprawling-type quadruped robot. As a demonstrator, we developed the sprawling-type quadruped robot named TITAN-XIII. For a lightweight and compact leg, the right-angle type wire driven mechanism is adopted to the robot. To confirm its performance, several experiments were carried out and the robot walked at 1.38 m/s and COT of 1.76 was achieved. Finally, we compared the performance of TITAN-XIII with other quadruped robots, and confirm that its performance is almost same level as mammal-type quadruped robots.

To avert potential crisis from Japan's aging infrastructure and declining birth rate, the Japanese Government is planning to introduce robotic technology for the inspection of social infrastructure (such as pipes, dams, and bridges). Recording underwater positions is a difficult task for human divers who undertake conventional dam inspections. This study presents the Anchor Diver 5.2 system for efficient and effectual dam inspection. Anchor Diver 5.2 is based on an extended-tether-maneuvered remotely operated vehicle (ROV) equipped with cameras. The ROV is lowered into water by a hoist system from a boat and implements a visual survey of the concrete underwater structure. To improve the visibility of the ROV in murky and cloudy water, a novel concept named Water Loupe is proposed. In addition, a simple boat-fixing method is proposed to provide a stable base on the water surface, and the underwater position of the ROV, which cannot be accessed by global positioning systems, is recorded using a feasible localization method. Finally, the developed system was evaluated in field experiments conducted in the Amagase Dam, Japan, and its merits and problems are discussed.

We have been developing a far-reach tethered working tool between mobile platforms. The main components of the system are the following: a tethered tool, two mobile platforms, two wire winding mechanism (winch). This paper deals with the winding control system for winches and the cooperative control system for mobile platforms. The cascade PID control strategy was introduced into winding control. The cooperative control system was developed based on leader-follower type control and virtual impedance control. The prototype system was verified by the experiments. A tethered tool reciprocated along a horizontal direction between cars while a slave car ran in parallel to a master car using virtual impedance control and a laser range finder.

Nowadays, social infrastructures in Japan are rapidly becoming old and many facilities which help Japanese people to make a good life have various problems. We have to immediately develop new technologies which enable us to cope with those problems efficiently and effectively. The objective of this research is to develop two key technologies. One of them is a means which enable us to take clear movies in turbid water, and the other is an attitude control method of underwater robots because the robots have to go to designated points. First, we designed Anchor Diver 4.1 for developing die attitude control. Second, we made a new underwater robot named "Anchor Diver 5.0" which has a clear case and a water proved camera. Then, we show results of practical experiment at Miyagase - dam in Kanagawa prefecture and evaluate the means we adopted in this research.

To understand the characteristics of ultrasonic wave propagation in concrete more completely, we propose a time domain simulation tool based on the finite integration technique (FIT) and an image-based modeling approach. When modeling ultrasonic wave propagation in concrete, it is important to introduce three-dimensional mesoscopic and microscopic structures because ultrasonic waves in solids are transmitted by mechanical interaction between adjacent media. In this paper, wave velocity, center frequency, and attenuation of ultrasonic waves in concrete are evaluated quantitatively by comparing the waveforms obtained by FIT simulation with those obtained by experimental measurement. It was observed that these factors were in good agreement between the simulation and measurements. It was also observed that amplitude of the transmitted signal was sensitive to the allocation pattern of the aggregates. Thus, attenuation due to multiple scattering by aggregates is more dominant than the attenuation by intrinsic absorption and geometrical spreading in concrete.