Kenjiro Tadakuma

Aerial Hose Type Robot by Water Jet for Fire Fighting

Disaster response, especially fire-fighting and rescue, is highly risky for firefighters engaged in action. As a result, many robots intended for fire-fighting have been proposed. However, it is difficult for them to directly access fire sources because their mobility is limited. Specifically, existing robots are large and heavy. Therefore, we propose a novel hose-type robot, which can fly directly into the fire source via a water jet. First, to control the reaction force for stable flying, we developed a nozzle module. By combining two nozzles whose outlet direction can be controlled, the resultant reaction force can be controlled. Finally, we developed a robot with a nozzle module and conducted an experiment. The experiment demonstrates that a robot with a length of approximately 2 m can fly stably in the air by leveraging the water jet. In addition, the head direction can also be controlled.

Two axes orthogonal drive transmission for omnidirectional crawler with surface contact

In this paper, we propose an omnidirectional mobile mechanism with surface contact. This mechanism is expected to perform on rough terrain and weak ground at disaster sites. In the discussion on the drive mechanism, we explain how a two axes orthogonal drive transmission system is important and we propose a principle drive mechanism for omnidirectional motion. In addition, we demonstrated that the proposed drive mechanism has potential for omnidirectional movement on rough ground by conducting experiments with prototypes.

Planar Omnidirectional Crawler Mobile Mechanism—Development of Actual Mechanical Prototype and Basic Experiments

This letter proposes a planar omnidirectional crawler mobile mechanism. This mechanism is the basis for the mobility of search and rescue robots. A planar omnidirectional crawler aims to facilitate penetration into a narrow path and soft or fragile ground. In this letter, the effectiveness of the proposed transmission mechanism is experimentally determined. In addition, a planar omnidirectional crawler equipped with a transmission mechanism was developed, and its characteristics were investigated through experiments for the pressure applied to the ground.

Jamming layered membrane gripper mechanism for grasping differently shaped-objects without excessive pushing force for search and rescue missions

ABSTRACT A gripper comprising a jamming membrane was developed with the capability of grasping collapsible, soft, and fragile objects without applying heavy pressure. In disaster sites, it is necessary for robots to grab various types of objects, such as fragile objects. Deformable grippers that contain bags filled with powder cannot handle collapsible or soft objects without excessive pressure. Changing powder density relatively by changing inner volume is one approach to overcome this problem. By expanding the concept and simplifying the variable inner volume of the gripping mechanism, we developed a jamming membrane comprising the following three layers: outer layer and inner layer made of rubber and a powder layer in between the outer and inner rubber layer. This jamming membrane allows collapsible, soft, or fragile objects to be held securely without applying too much pressure. We designed and developed a prototype of the jamming membrane gripper. Our experiments confirmed the validity of the proposed jamming membrane mechanism. GRAPHICAL ABSTRACT

A self-locking-type expansion mechanism to achieve high holding force and pipe-passing capability for a pneumatic in-pipe robot

This study proposes a self-locking-type expansion mechanism for in-pipe robots. Previously, we proposed a highspeed locomotion mechanism using pneumatic hollow-shaft actuators; however, this mechanism lacked holding force and could not pass through a bent pipe. The proposed mechanism generates a large holding force and can easily pass through a bent pipe by invoking a self-locking phenomenon. We conceptualize and design the novel expansion mechanism and introduce its associated mathematical model to formulate the holding force and mechanism design. The characteristics and capabilities of the mechanism are elucidated by experiments. From the experimental results, we optimize the applied pressure and the design of the mechanism. The proposed mechanism generates a maximum holding force of 69.7 N, which is 5.2 times higher than that of the previous mechanism, and drastically improves the robots bent-pipe-passing capability. Finally, the performance of this mechanism is confirmed in a simulated pipe test. In this trial, a robot equipped with the proposed mechanism smoothly and steadily moves through complex pipe configurations, including the vertical and bent pipes.

UAV with two passive rotating hemispherical shells for physical interaction and power tethering in a complex environment

For the past few years, unmanned aerial vehicles (UAVs) have been successfully employed in several investigations and exploration tasks such as aerial inspection and manipulations. However, most of these UAVs are limited to open spaces distant from any obstacles because of the high risk of falling as a result of an exposed propeller or not enough protection. On the other hand, a UAV with a passive rotating spherical shell can fly over a complex environment but cannot engage in physical interaction and perform power tethering because of the passive rotation of the spherical shell. In this study, we propose a new mechanism that allows physical interaction and power tethering while the UAV is well-protected and has a good flight stability, which enables exploration in a complex environment such as disaster sites. We address the current problem by dividing the whole shell into two separate hemispherical shells that provide a gap unaffected by passive rotation. In this paper, we mainly discuss the concept, general applications, and design of the proposed system. The capabilities of the proposed system for physical interaction and power tethering in a complex space were initially verified through laboratory-based test flights of our experimental prototype.

Use of active scope camera in the Kumamoto Earthquake to investigate collapsed houses

The Kumamoto Earthquake occurred in April 2016. We conducted an investigation using the active scope camera to examine the interiors of the collapsed houses. The robot video scope can move by itself to probe narrow gaps. We could safely gather information by inserting it inside houses. We further considered the future possible improvements to the robot based on the investigation. We also determined the constraints to be considered for the robot operation in disaster areas. In addition, we created a test field imitating the features of collapsed houses. We used this field to evaluate our robot mobility and related technologies that are being developed for future applications.

Development of a spherical tether-handling device with a coupled differential mechanism for tethered teleoperated robots

Tethered robots often experience entangling of their cables with obstacles in uncertain disaster environments. This paper proposes a spherical tether handling device that unfastens a robots tether during surveys by releasing the tether and carrying it aside. By using a differential mechanism, the device drives shells and rollers that hold the tether. On flat surfaces, the device moves forward by driving the shells. When the device climbs over steps, the rollers are driven by the differential mechanism to pull the tether automatically. After prototyping the device, we confirm the surmountability of the proposed device against steps. The results show that the device can climb a height 90.9% of its diameter. We also demonstrate a scenario to handle the tether and untangle multiple tangles in an environment with several obstacles.

Study on the inertial stabilization of a payload by center of gravity displacement

The aim of a gimballed stabilization system is to maintain the orientation of a sensor, camera or other device constant, isolating it from disturbances caused by the movement and accelerations of the vehicle on which it is mounted. In this paper we study the design of an inertially stabilized platform (ISP) to be mounted on a host vehicle. The stabilizing mechanism consists of a two-axis gimbal with passive joints onto which a payload tray and a counterweight with adjustable position are assembled. We propose to achieve stabilization of the payload by adjusting the position of the counterweight in three dimensions to locate the center of gravity of the payload-counterweight system at the crossing point of the passive gimbal orthogonal rotation axes. Achieving static balance with the proposed method has been confirmed with an experimental setup.

Sensor based controlled leg type automatic landing system for aerial vehicles

Hovering is an indispensable function of helicopters for the tasks on uneven terrain. But hovering is dangerous and needs high control technique of the operator and a large amount of fuel. Therefore, we have been proposed Leg Type landing gear system for aerial vehicles that can adapt to uneven terrain as a substitute for hovering. We named this automatic landing system on uneven terrain ALS. In this paper, the developed ALS that consists of ultrasonic distance sensors, micro switches, and leg system is introduced. Experimental results of landing on uneven terrain with hanging cord, flight and landing without cord and measurement of power consumption are shown.