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Current/Ongoing work

Self-structured rail system for Hazardous Environments


Unmanned robot operation is highly anticipated for use in hazardous environments such as a nuclear accident and mine accident sites. We propose an automated construction system for robot locomotion and operation platform in a severely disturbed environment. The platform is intended to enable specialized working robots to have access to any cube-diced operation point, and to build a rail both for the platform itself and for specialized working robots. The entire platform structure is modularized, which means that the structure comprises multiple modules. They are assembled and constructed through cooperation of a transfer robot and a constructor robot.

3-Dimensional Construction of the Modularized Rail Structure in Various Posture Conditions


Our group is developing an automated construction system for a modularized rail structure in the decommissioning project of the Fukushima Dai-ichi Nuclear Power Plant. The system can construct locomotion and operation infrastructure for robots. In previous studies, we have developed multiple robots and modules. However, 3-dimensional construction of these modules has not been verified. To realize it, we redesigned the constructor robot and conducted module connecting experiments. The experiment results show that the pushing motion and improving the stiffness of the constructor robot’s grasping part increase the successful rate of module construction in vertical downward direction; the most difficult condition.

Construction Planning for Self-structured rail system


Unmanned robot operation is highly anticipated in TEPCO Fukushima I Nuclear Power Plant because of rubbles and high radiations. We have developed the construction planner for the self-structured rail system which enables to estimate required modules, robots, and time quantitatively.
The developped planner can decrease drastically the search space for assigning type and attitude to each module, by installing heuristics based on geometrical constrained condition.

This study received Best Application Paper Award (by IET) in DARS 2016, 13th International Symposium on Distributed Autonomous Robotic Systems.

HanGrawler: High-speed and Large-payload Ceiling Mobile Robot Using Crawler

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HanGrawler is a ceiling-mounted mobile robot with high-speed mobility and the ability to freely select and adjust its route under a ceiling plate. HanGrawler hangs from the holes of a perforated metal ceiling plate using newly developed mechanically constrained hanging mechanisms mounted on crawler-type traveling equipment. These mechanisms continuously grasp the ceiling holes while moving in a straight line. Specially designed turntables are installed at certain ceiling points to change the HanGrawler movement direction to facilitate two-dimensional motion. HanGrawler can travel linearly at 0.1 m/s, turn at an 8.5◦/s rotational speed, and carry a maximum load of 60 kg.

A Tablet Interface for a Direct Vision Teleoperation of an Excavator


In recent years, worker shortages in the field of urban construction are looming as an important issue. To address this difficulty, direct-vision remote control of a construction machine can be an effective solution by which a worker can play not only the role of an operator but also play the role of a manual laborer. This study examines a new direct-vision remote control system for an excavator using a tablet device. To realize an intuitive interface, we propose the following graphical user interfaces (GUI) of two kinds: input bucket velocity using virtual joysticks, and input bucket position by dragging a bucket. We conducted a usability evaluation experiment simulating a horizontal digging operation. The experimental result concludes that proposed two GUIs superior to the conventional interface in task execution time, accuracy, and subjective usability evaluation.

Manufacturing system for multitasking machining with scalability, portability and parallelism


We aim to realize modularized-structure and Multiple-points Simultaneous Machining System (MS-cubic) to replace existing CNC-based manufacturing systems, which is inefficient for manufacturing huge products such as air mobility expected to spread widely. By modularizing its structure, MS-cubic can process multiple points simultaneously and change its workspace. We designed and made prototypes of the machining unit, the rail module and a rail traverse module, which are the major components of this system. They are designed to be portable in weight, easily connectable, rigid enough to drill, and capable of supplying fluid and power to the other units. Experiment results showed that the prototype of MS-cubic comprising a machining unit and rail modules achieved a drilling process.

WInBot: A Disc Cutter Wear Inspection Robot for a Tunnel Boring Machine


During excavation, the disc cutter (DC) of a tunnel boring machine (TBM) will experience wear. WInBot, a DC wear inspection robot, is developed for 5 m-diameter-class TBMs and two wear measurement methods are proposed. WInBot has a high expansion ratio actuator to allow operation in the narrow space around the cutter head. The measurement arm can extend widely and can be compacted 2.7 and 1.5 times for vertical and horizontal expansion and contraction ratios, respectively. WInBot acquires point cloud data for a DC surface or other parts and estimates the amount of DC wear using an iterative closest point (ICP) matching algorithm. Experiments are conducted to examine the accuracy of the proposed measurement methods. When only DC surface data is used, the estimation accuracy drops when the DC is severely worn and its geometric features disappear. The other method, which uses additional parts, is resistant to the difference in DC wear and achieves measurements accurate to 1 mm.

Development of a multi-link wrist band for hand shape recognition based on wrist contour and band flexion

In recent years, there has been a demand for hand shape recognition technology for intuitive user interfaces based on hand gestures. Hand shape recognition using a wearable wrist contour measurement device developed in previous research is expected to be a highly operable user interface that does not require pressing a sensor to the wrist, thus reducing the burden on the user. On the other hand, there is a problem that the attachment condition changes every time the device is put on and taken off, which decreases the recognition rate. Therefore, in this research, we took the approach of measuring the attachment condition in addition to the wrist contour. It is possible to refer to appropriate learning data based on information about the attachment condition. We have developed a multi-joint wrist band that can measure simultaneously wrist contour and band flexion including information on the attachment condition.

Wrist Wearable Device for Hand Shape Recognition Using Wrist Contour

Recently, more and more companies and researches have interest and develop a natural user interface using gestures for the human computer interaction such as TV games. In this work, we developed a wrist wearable sensor device measuring wrist contours for hand shape recognition. Using wrist contours gives no stress on the wearer and doesn't limit usage circumstances. We are trying to recognize hand shapes robustly by measuring wrist contours which vary with contraction or flaccidity of flexor and extensor tendons of fingers. On the measurement band, infrared distance sensors are mounted in two lines and each line has 75 sensors. It can measure distance between surface of wrist and the measurement band all over the wrist with 2.5[mm] density and 10[Hz] frequency. We collected data of several hand shapes and arm postures of many subjects with the device, and analyzed variation of wrist contour which differs or doesn't differ according to individuals.

A Relative Position/Posture Measuring System for Platooning Vehicles


We propose a new platooning vehicle that uses a coupling device not for the traction of following vehicles but for the measurement of relative position and orientation between leading and following vehicles. The following vehicles are driven by their own motors. We are developing the relative position and orientation measurement system. In the coupling device, multiple distance sensors are equipped around the pin. These sensors acquire the distance between the pin and a hexagonal ring. The array of distance values is converted to the relative position and orientation of vehicles using Data-driven algorithm. The developed measurement system is evaluated using hardware in the loop simulation (HILS) that simulates multiple vehicles’platooning drive. Therefore, the system capabilities have been evaluated not only by the measurement precision but also by the platooning performance. The experimentally obtained results demonstrate that the proposed measurement system is sufficiently valid and feasible.

A Balancing Control for Platooning Vehicles


Ultra-compact mobility attracts attention as a means of transportation for a few people in urban areas. It is possible to reduce the number of workers by platooning which consists of a manned leader vehicle and unmanned follower vehicles. We have proposed a platooning system of Ultra-compact mobility, which is based on estimation of vehicles' relative position measured by the coupling device attached to vehicles' front and back. In this research, two control schemes were proposed for turning a curve without failing to maintain connected state. The method which shifted tracking objective trajectory of follower and the method which balanced trajectory tracking control and device keeping control in angular velocity control were developed. Platooning experiment using 1:16 scale-model vehicles revealed balancing scheme is effective.

Wear estimation for grinding wheel by optically measuring chip size distribution


In theory, chip size distribution changes due to grinding wheel wear in cylindrical grindings. However, the relationship between wear and chip size distribution is not verified quantitatively.Therefore, the purpose of this study is to estimate grinding wheel wear by verifying the relationship between wheel wear and chip size distribution experimentally. First, the device to collect chips during grinding was developed. Particle tracking system measures chip size which is on the order of µm, then chip size distribution is associated with wheel surface topography and workpiece surface profile. As a result, the proportion of chips whose perimeter are more than 1000 µm increases when a grinding wheel becomes worn contrary to the established theory that slender chips are unlikely to be generated when grinding wheel is worn.

Laser cutting defect recognition of steel metal sheet processing


Laser cutting process becomes an essential technology for high-speed and flexible sheet metal processing. This study aims to detect defective cuts by sensing the emission of light caused by laser cutting. The proposed method acquires the spectra of the light generated during processing using the sensors installed in a laser head and the newly developed data analysis software converts the light spectra data into image data. The image processing software extracts edges of two images, and emphasizes the periodic features in normal laser cutting. A one-class SVM (Support vector machine) recognizes defective cuts from the extracted features. Verification tests using multiple normal and abnormal cuts data has confirmed that the proposed method can successfully detect defective cuts.

Suspended work

Rail Structure Supporting Mechanism using Resin Foam


For hazardous environments, our research group is now developing an automated construction system of robot locomotion and operation whose rail structure is modularized. To realize solid fixation of the rail structure against an environment, a rail structure supporting mechanism is essential. The developed mechanism uses resin foam for three different functions; actuator, adhesive material and structural material. This characteristic realizes quite compact but strong temporal supporting performance.

Functionally distributed machines for underground mining


Recent years, underground mining method is becoming popular because of its potentially high productivity and efficiency. In this method, a mining machinery; load haul dump (LHD), is used as both an excavator and a transporter of ore. Our research group proposes a distributed system that realizes the excavation and transport functions with separated vehicles, an excavator and a transporter. In addition, we proposes a mining map and configurations suitable for the proposed distributed system. To evaluate the productivity of the proposed system, a simulation environment has been developed. Analysis using the simulator reveals what performance factors of the excavator and the transporter have large impacts on the productivity. Simulation results also demonstrate the difference of potential between LHD system and the distributed system that can be explained based on their functions allocation.

Imitation-based Control of Automated Ore Excavato


Resource exploitation work involves substantial number of dangerous and grueling tasks. Automation of mining machines serves to protect operators from a hazardous environment. This study aims to develop an automation method with high productivity for the fragmented rock pile excavation which is a typical task in resource exploitation. In order to realize a high productive bedrock excavation, the excavator has to change excavating motion according to the change of the rock pile condition. Skilled operators have enough knowledge about the bedrock condition and excavating motions, therefore, they are able to select appropriate excavating motion according to the rock pile condition. This paper proposes an imitation-based autonomous excavation method which includes a rock pile condition recognizer and an excavating motion planner utilizing operators' know-how.

Real-time and Wide-ranging Internal Observation of Diesel Particulate Filter


Particulate Matter (PM) contained in the exhaust gas of Diesel engine has negative effects on the respiratory organs of human body. As a way of reducing the amount of PM contained in the exhaust gas, Diesel Particulate filter (DPF) is widely used. In this research, we have developed a visualization method to realize the real-time and wide-perspective internal observation of DPF. We conducted an observation experiment using a diesel engine and DPF. We have succeeded to acquire internal images of DPF when PM deposit layers have collapsed, channel plugging have happened and so on.

HangBot: a Ceiling Mobile Robot with Robust Locomotion under a Large Payload


This research aims to develop a ceiling mobile robot that can sustain a large payload and can locomote freely under a ceiling space. In our approach, a perforated metal, one of the recent popular architectural materials, is utilized as a ceiling plate and the robot hooks and hangs the sequential holes of the ceiling plate by mechanical constraint. To realize the robot, we developed three key mechanisms, (1) ceiling hanging mechanism for the perforated metal, (2) horizontal locomotion mechanism like an inchworm, and (3) pantograph mechanism for smoothing horizontal locomotion speed and for load balancing. Those basic methodologies of the robot is to be preserved as patents, therefore, we have already applied for PCT. Now we are searching companies that can execute a collaborative research with us.

High Efficient Traction Drive System Using Piezoelectric Actuator

Traction drive is a useful power transmission method for resolving noise problem of electric vehicle. It is composed of pressed two rollers. Oil becomes glassy because the pressure between rollers is high, and the torque is transmitted from input roller to output roller. Its efficiency is lower than gears because of the normal force between rollers. Adjustment of the normal force is necessary to increase the efficiency. In this study, piezoelectric actuator is used for adjusting the normal force. It is an actuator deformed by the voltage, and known for its large force and small displacement. It is undesirable to use piezoelectric actuator with a low rigidity force sensor. Therefore, we developed a normal force control method by sensing the slip between rollers instead of the normal force. Two rollers machine is manufactured to confirm improvement of efficiency using the proposed control method.

Growth Measurement of Tomato Fruit based on Whole Image Processing

Crop grow measurement technologies are important to increase the farm productivity. Detection and measurement of fruit volume are useful for forecasting and harvesting applications. Some environmental challenges such as lighting conditions or occlusions make the fruit detection difficult. Our approach is based on features extraction from images through a sub-image clustering technique. Then images being described as a number of pixel in various labels are used in a regression model to estimate the fruit volume. The validity of the proposed method in experimental condition is successfully verified. The method is evaluated also in a field condition but results were inferior to the expectation.

A tomato fruit volume estimating robot

In recent Japanese agriculture, promotion of data mining using knowledge of skilled farmers is getting remarkable. In tomato cultivation, it is important to acquire size data of green immature tomato fruits while they are growing. To achieve the goal, we have developed a tomato monitoring robot that searches autonomously a proper position for observation. The mobile robot patrols around a tomato field and finds out fruits. It generates fruit 3D point cloud using an on-board stereo camera, and estimates fruit width by analyzing point cloud. Furthermore, the estimation result is immediately evaluated to improve the quality of acquired data by rejecting unreliable data and retrying the measurement if necessary.

Daily walking ability assessment system with a distance sensor array


Walking ability has a strong impact on the health of elderly people. However, daily walking ability assessment was difficult because it was measured manually by medical or care staffs in medical facilities or elderly houses. In this work, we propose a system for estimating walking ability that can be easily installed in a home. This system uses multiple inexpensive distance sensors as an array device, which allows to estimate walking speed and step length. We conducted an experiment on 14 elderly people. In the experiment, elderly people walked with speed of 0.48-1.05m/s and step length of 0.29-0.58m. The experimental results show that the Mean Relative Error (MRE) were 6.7% in walking speed and 3.9% in step length. This superior results were realized by our originally developed device and algorithm.

CFloor: An Electrostatic Capacitive Floor Sensor for Human Position Monitoring


We are developing an electrostatic capacitive floor sensor system with low-cost, easy-installation and maintenance-free advantages for monitoring human position in a living space. Features of the sensor system are conciseness that the system is made of very simple parts, that means it is inexpensive, and modularity that enables easy expansion of the sense area. Experiments confirmed the sensor characteristics for human monitoring and showed the feasibility of the accurate sensing with only concise recognition and filtering processes.

Home-use logistical support robot system


With industrial or economical developments, our living space is being over-flown with too much objects and information. To solve the problem, we present a new living space system: a home-use logistical support robot system, which utilizes IT (Information Technology) and RT (Robot Technology). A core technology of our system is intelligent container (i-Container) which plays a role of logistical mediator between humans and robots. When people access to an object via i-Container, i-Container recognizes flow of the object and stores the logistical data as a permanent memory.

On the other hand when robots access to an object, robots need not to manipulate each object but need to handle i-Container. Such scheme may be easy and efficient for robots.
The system is composed of (A) a ceiling mobile container transfer robot, (B) a home-use automated container warehouse which realizes high space efficient storage and can collaborate with the container transfer robot and (C) iDock: an intermediate access point which is installed in our personal room (ex. Bed room, Child room).

By integrating these single function robots, we present a novel life style which can rescue us from over-flown objects and information.

intelligent Container (i-Container)

In our home-use logistical support robot system, an intelligent container (i-Container) plays a role of mediator between humans and robots, as a core technology of our system. So far, there were many researches and development about object manipulation, and thorough those effort we had acquired a lot of knowledge and know-how’s. Especially in industrial assembly application, fast and precise handling way achieved to realize high performance manufacturing system.

On the other hand, home robots must manipulate various objects comparing industrial application, and such flexible robotic manipulation is not easy in current robotics. Our goal is to realize a high efficient home-use storage/retrieval system, therefore the manipulation procedure is only one aspect of the whole system and not main topic. In our system i-Container is specialized in the fixing task and not only supports human to realize easy fixing but also supports robot to “support” human by their capabilities.

Concretely speaking i-Container can recognize contents of itself by reading RFID tags of the contents, make it easy for visual measurement system to acquire the position by blanking LED markers, and physically support the robot manipulation by guide structures.

In addition, i-Container has many variations. For storage use, 3 classes (S, A, E) are prepared to match the cost V.S. storage term problem, and compact refrigerator container, entertainment (DVD & writing desk) container and lavatory (Tooth brashing) container were developed for elder life support.

Container transfer robot


Container transfer robot was developed to realize a robust container transport motion without interference to humans in a living space. In general, there are many obstacles (daily-use object / furniture) on the floor of a living space. Therefore robots in the environment need to recognize the obstacles and plan their paths effectively. Especially in Japan, width of a corridor is small for human and robot to pass through simultaneously.

To solve the above problem, we present a novel and simple approach to utilize upper ceiling space as a main motion space of robots.

Additionally our living space has many disturbance factors for robots: ex. lighting condition, moving obstacles and residents themselves. To overcome the disturbance effect, the robot is implemented with some compliant (flexible) mechanisms. High stiff robot can realize precise and high speed motion but is not good at absorb some errors resulted from the environmental disturbance. Surely home robot should not injure the resident so the flexible mechanism can show good performance at reducing the accidental impact shock between human and the robot.

Home-use automated container storage/retrieval system

Home-use automated container storage/retrieval system (refer to s/r system) is an instrument to realize high space efficient storage of i-Containers and collaborative transport task with the Container transfer robot. An existing container warehouse requires a great deal of speed efficiency therefore users and the warehouse are separated by safety fences. But in home application a warehouse must cooperate with the users to keep the current living space and modern life style.

To achieve cooperative robot motion, horizontal and vertical motions of the s/r system are installed in a different body. To do so, the body size can be small and evacuation mode can be available by lifting the horizontal transporter up to ceiling.

Moreover it is not easy for the handling robot (horizontal transporter) to operate robustly i-Container which is placed by human. To achieve robust motion, a soft handling strategy; “caging” was introduced; therefore the robot can manipulate i-Container smoothly even placed by human without precise positioning.

iDock: an intermediate instrument for home-use container logistics


“iDock” is an intermediate instrument which performs like an accesses point or hub in our home-use logistical support robot system. In general iDock is in compact mode not to invade the living space, but when necessary , its body and table are actuated to perform its capabilities.

When a user places i-Container on iDock, iDock recognizes the contents of i-Container by reading RFID tags and decides the storing place; ex. Upper ceiling storage or shelf type storage or not storing in storage. iDock has a guide plate to realize smooth i-Container delivery motion to the Container transfer robot. Thanks to the guide plate time efficiency and success rate of the delivery mission increases drastically.

Another feature of iDock is movable RFID antenna to recognize the contents of i-Container, the motion of antenna achieves robust RFID recognition despite of the position and posture of target RFID tags.

TansuBot : Object Search Supporting Instrument


“TansuBot” is a drawer type instrument to support daily-use small object search. Each drawer has a LED and an open/close detect switch. The switch acquires usage history. A wall moving robot in the back of the instrument has a portable camera to shoot the inside of drawers and has an extensive arm to realize pop-up function (pushing each drawer forward). By using the acquired information, users can search an object with a portable device such as a smart phone. In addition, the candidate of drawers that may contain the target object is emphasized by blinking LED and pop up action. These functions make the time short for searching an object. To keep the efficiency as storage, the space for moving robot is designed to be as small as possible. Considering the introduction of the instrument into a small store or a house, main parts are made of wood. They realize production cost reduction and user-friendly texture and appearance.

exStacker: A Non-Industrial Stacker Crane


Non-Industrial Stacker Crane enables humans to use high place for storage. Stacker crane is transport equipment carrying a container. In this research, we initially omit expensive sensors and actuators, and tried to develop an easily-installed stacker crane whose price is reasonable for home-use or small-shop-use.

The presented instrument has three features. (1) The instrument adopt a new storage system that makes containers deirectly hung on a wall. (2) A novel 2-DOF combined mechanism is composed of T-shape timing belt and two brakes. It realizes container lifting and inserting motions with only a single input handle. (3) The stacker crane can be easily extended into automatic mode just by adding electric and electronic components.

RoboDoor: A supplementary automatic door device


Robo-Door is an supplementary automatic door device by a wheel actuation. For home robots, door open/close is an essential but difficult task. Moreover, it is not practicable for robots without arms (ex. Roomba) to operate a door by themselves. Installing a door actuating device, the environment improves those robots' performances and promotes installation of current robot systems to living space. In addition, automatic open/close of a door is also helpful for humans with physical handicap, especially they use wheel chairs. Robo-Door selects a method of actuation by wheel. One advantage of actuation by wheel is simplicity of mechanisms Moreover, it could be installed to both a hinged and slide door, changing the direction of the device. In addition, Robo-door realizes an installation methodology without fabrication like a punch on a door, which is a Robo-Door's feature that other commercial products do not have.