Faculty Profiles - NAKAJIMA Shuro

Published Papers - NAKAJIMA Shuro

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Gait algorithm of personal mobility vehicle for negotiating obstacles

Shuro Nakajima （Part： Lead author,　Corresponding author )

Disability and Rehabilitation: Assistive Technology 9 ( 2 ) 151 - 163 2014.03 [Refereed]

Purpose: Personal mobility vehicles (PMVs) are under active development. Most PMVs are wheel-driven, a mode of transport notable for its efficiency. However, wheeled PMVs tend to have poor mobility against negotiating obstacles. The four-wheeled vehicle RT-Mover PType 3 has been developed featuring wheeled legs capable of leg motion. This allows the PMV to overcome uneven terrains, including a step approached at an angle, which ordinary wheelchairs cannot negotiate. Method: This article discusses a gait algorithm in which a leg executes the necessary leg motion when optionally presented with obstacles on a road. In order to lift a wheel off the ground and perform a leg motion, the support wheels must be moved to support points to ensure that the vehicle remains stable on three wheels. When moving towards the target support point, a wheel may encounter another obstacle, and a response method for this case is also described. Results: To assess the gait algorithm, several configurations of obstacles were used for performance tests with a passenger. The capabilities of the PMV were demonstrated through experiments. Conclusion: We proposed a novel gait algorithm for our PMV and realised the proposed motion pattern for PMV-based negotiating obstacles.Implications for RehabilitationOur single-seat personal mobility vehicle, RT-Mover PType 3 features wheels attached on legs capable of performing leg motion, which allows the vehicle to traverse rough terrains in urban areas.We proposed a gait algorithm for RT-Mover PType 3 consisting of a series of leg motions in response to rough terrain. With this algorithm, the vehicle can traverse not only randomly placed obstacles, but also a step approached at an oblique angle, which conventional powered wheelchairs cannot navigate.Experiments with a passenger demonstrated the effectiveness of the proposed gait algorithm, suggesting that RT-Mover PType 3 can expand the mobility and range of activities of wheelchair users. © 2014 Informa UK Ltd.

Improved Gait Algorithm and Mobility Performance of RT-Mover Type Personal Mobility Vehicle

Shuro Nakajima （Part： Lead author,　Corresponding author )

IEEE ACCESS ( IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC ) 2 26 - 39 2014 [Refereed]

We have developed a personal mobility vehicle (PMV) with four driven wheels that is capable of negotiating obstacles with a leg motion mechanism. When obstacles are encountered, wheels are lifted, moved ahead in a stepping-like motion, and lowered back down, thereby allowing the PMV to advance further. In our previous paper, we discussed the principle of the gait algorithm used by our PMV, in which wheels are utilized as legs to negotiate obstacles. In the original algorithm, when the wheels encountered terrain that might require leg motion to traverse, the system determined whether such motion was applicable and, if it was, orchestrated a series of leg motions. However, there were terrains that could not be negotiated using the original algorithm. In this paper, we propose an improved gait algorithm, in which when the vehicle encounters terrain intractable by leg motion with its current posture, the vehicle changes its posture until it can traverse that terrain. We verified the effectiveness of the improved gait algorithm through a variety of mobility tests with a passenger. In addition, we present numerical data on the range of terrain topologies that could be negotiated by the proposed algorithm.

Design Guidline for a Rough Terrain Mobile Platform, RT-Movers

Shuro Nakajima, Takuma Kondo （Part： Lead author,　Corresponding author )

設計工学 ( 日本設計工学会 ) vol.47 ( no.9 ) pp.423-432 - 432 2012.09 [Refereed]

In this paper, we propose the guideline for designing a rough terrain mobile platform, named a series of RT-Mover, according to a target environment, because we have already developed five RT- Movers and begun to grasp the point of designing it. RT-Movers have the strength that they have both of wheel mode and leg mode in spite of the simplicity of mechanism. The purpose of this paper is to introduce the method to decide boundary dimension of this robot and to derive the necessary torque and angular velocity of each axis. After proposing the methodology of designing RT-Movers, we introduce the two samples of RT-Movers.

Proposal for An IR System to Support Automatic Control for A Personal Mobility Vehicle

Taro Fujikawa, Shuro Nakajima

2012 IEEE INTERNATIONAL CONFERENCE ON ROBOTICS AND BIOMIMETICS (ROBIO 2012) ( IEEE ) 2207 - 2212 2012 [Refereed]

We propose a supporting system for automatic control of personal mobility vehicles (PMVs) to pass through a narrow space in indoor environment. This system consists of IR markers located on an entrance of a narrow space and an IR sensor to mount on a PMV. An IR sensor calculates relative distance between itself and an IR marker and angle of approach to pass through on a marker. To validate the proposed system we perform both experiments to estimate accuracy of calculated relative distance and angle and to demonstrate automatic control using our manufactured PMV. These results show that the proposed IR system is effective in path guidance for PMVs.

Concept of Adaptive Gait for Leg-wheel Robot, RT-Mover

Shuro Nakajima, Kazuhisa Ietomi （Part： Lead author,　Corresponding author )

2012 IEEE INTERNATIONAL CONFERENCE ON ROBOTICS AND BIOMIMETICS (ROBIO 2012) ( IEEE ) 293 - 300 2012 [Refereed]

We have been conducting research into developing sufficient mobilization through usage of the leg-wheel type robot known as "RT-Mover" in its intended environment. This robot uses 4 drive wheels and 5 driving axes to provide simple mechanics, while also delivering a wheel mode and a leg mode. Past research has confirmed the robot's underlying mobilization capability on standard terrain, examined the wheel mode's mobility, and tested the robot's capability to move over rough terrain not suitable for wheel mode via the leg mode. This paper proposes concept of adaptive gait using leg functions. When the wheels come in contact with convex terrain, adaptive gait will allow movement to continue through the use of leg motions. This paper provides a proposal concerning the basic operation of adaptive gait and validates their efficacy using the results of simulations and experiments.

PERFORMANCE OF THE ADAPTIVE GAIT FOR THE LEG-WHEEL ROBOT, RT-MOVER

Shuro Nakajima, Kazuhisa Ietomi （Part： Lead author,　Corresponding author )

ADAPTIVE MOBILE ROBOTICS ( WORLD SCIENTIFIC PUBL CO PTE LTD ) 603 - 610 2012 [Refereed]

We have developed a robot,called RT-Mover, which shows adequate mobility performance on targeted types of rough terrain.It has four drivable wheels and two leg-like axles but only five active shafts.A strength of this robot is that it realizes both a leg mode and a wheel mode in a simple mechanism.We are now researching and developing an adaptive gait algorithm targeting terrain on which random areas of raised terrain exists.In"adaptive gait" only the wheel in contact with the raised terrain performs a leg motion and movement continues. In this research,we numerically analyzed the range of raised terrain which can be traversed using adaptive gait, and verified movement ability through experimentation.From those results,we have found that adaptive gait allows motion from an arbitrary posture in an environment with arbitrarily positioned raised terrain if the height of the terrainis within about 0.1[m].

Proposal for personal mobility vehicle supported by mobility support system

Shuro Nakajima, Taro Fujikawa （Part： Lead author,　Corresponding author )

2012 IEEE International Electric Vehicle Conference, IEVC 2012 1 - 6 2012 [Refereed]

Development of a Personal Mobility Vehicle for Rough Terrain

Shuro Nakajim

Proceedings of the 14th CLAWAR ( World Scientific ) 650 - 657 2011.09 [Refereed]

An IR system in the mobility support system to expand the field of activities for personal mobility vehicles

Taro Fujikawa, Masaki Shirata, Shuro Nakajima

2011 IEEE International Conference on Robotics and Biomimetics, ROBIO 2011 ( IEEE ) 571 - 576 2011 [Refereed]

In this paper, we propose a system called mobility support system (MSS) in order to expand the field of activities of personal mobility vehicles (PMVs). We validate a method using an infrared (IR) system that is one of the components of MSS for providing self-localization for PMVs. To this end, we use the IR system to perform experiments for estimating the angle of approach of the PMV toward an IR marker so as to pass through a narrow space such as a ticket gate in a station. Our results show that this system determined the angle of approach with accuracy. © 2011 IEEE.

Joint education program between technical high school and university for technical high school student through developing robots

Ryohei Shimanuki, Shuro Nakajima （Part： Corresponding author )

Journal of Robotics and Mechatronics ( Fuji Technology Press ) 23 ( 5 ) 840 - 849 2011 [Refereed]

This report details, in terms of the management and course content, joint projects between technical high schools in Chiba Prefecture, Japan, and a university. The projects were courses that intended to improve, through a wide range of manufacturing activities involving the development of robots, the manufacturing abilities and basic skills as working people of technical high school students. In 2009 and 2010, various high schools and a university ran courses in cooperation, and through questionnaire surveys we discovered the significance of the use of robots as an educational subject of study and learned useful points regarding the course content.

Hands-on education of robotics department for four years of college

Yasuo Hayashibara, Shuro Nakajima, Ken Tomiyama, Kan Yoneda

Journal of Robotics and Mechatronics ( Fuji Technology Press ) 23 ( 5 ) 789 - 798 2011 [Refereed]

In this paper, we introduce engineering education at the Department of Advanced Robotics, Chiba Institute of Technology. At the department, we try to teach useful knowledge and provide laboratory work leading to useful experience. One purpose of the curriculum is to enable students to design a system with a mechanism, control circuit, and computer programming. We then provide many lectures related to system design - control engineering, mechanics, mechanical dynamics, electronic circuits, information engineering, mechanical drawing, and so on - and provide laboratory work on related theory in the lectures. Laboratory work helps students understand abstract theories that are difficult to understand based on desk study alone. This laboratorywork continues fromthe first to fourth years. In addition, we provide many project studies. Some students try to develop their own systems through extracurricular studies. Through the project, students obtain much knowledge and experience. After introducing our curriculum, we discuss the results of this curriculum.

Proposal for step-up gait of RT-Mover, a four-wheel-type mobile robot for rough terrain with simple leg mechanism

Shuro Nakajima （Part： Lead author,　Corresponding author )

2010 IEEE International Conference on Robotics and Biomimetics, ROBIO 2010 ( IEEE ) 351 - 356 2010 [Refereed]

RT-Mover can move on continuous rough terrain using a motion control technique proposed in a previous paper[1]. There is, however, larger rough terrain in a real environment than in the previous paper, so, RT-Mover can not operate there using that technique. In this paper, a step-up gait for an upward step is proposed for use in discontinuous rough terrain. The flow of processes in the step-up gait and stability during the gait are discussed. The proposed gait is evaluated through simulation and experiment. © 2010 IEEE.

KINEMATICS FOR A ROUGH TERRAIN MOBILE ROBOT TO CLIMB UP A STEP

Shuro Nakajima （Part： Lead author,　Corresponding author )

EMERGING TRENDS IN MOBILE ROBOTICS ( WORLD SCIENTIFIC PUBL CO PTE LTD ) 825 - 833 2010 [Refereed]

The rough terrain mobile robot "RT-Mover", which is a leg-wheel-type robot built of very simple mechanism, can move on continuous rough terrain.(1) However, in a real environment there is also discontinuous rough terrain, where it can not get about. The step-up gait for an upward step has been studied to walk on discontinuous rough terrain. In this paper, a flow of the step-up gait is introduced. After that, kinematics to climb up a step is discussed in detail, and is evaluated through simulation and experiment.

Adaptive Gait for Large Rough Terrain of a Leg-Wheel Robot (Fourth Report: Step-Over Gait).

Shuro Nakajima, Eiji Nakano （Part： Lead author )

Journal of Robotics and Mechatronics 21 ( 2 ) 285 - 292 2009 [Refereed]

Concept of a Novel Four-wheel-type Mobile Robot for Rough Terrain, RT-Mover

Shuro Nakajima （Part： Lead author,　Corresponding author )

2009 IEEE-RSJ INTERNATIONAL CONFERENCE ON INTELLIGENT ROBOTS AND SYSTEMS ( IEEE ) 3257 - 3264 2009 [Refereed]

In many fields employing robots, e.g., wheelchair robots, rescue robots, and construction robots, those which can move on rough terrain are desired. A robot with a simple mechanism and high mobility for all-terrain is discussed in this paper. A novel type of four-wheel-type mobile robot is developed, and its design is discussed from a functional viewpoint. In addition, strategies for moving on rough terrain are introduced, and its fundamental capability of moving on rough terrain is verified through simulations and experiments.

Adaptive Gait for Large Rough Terrain of a Leg-Wheel Robot (Third Report: Step-Down Gait).

Shuro Nakajima, Eiji Nakano （Part： Lead author )

Journal of Robotics and Mechatronics 21 ( 1 ) 12 - 19 2009 [Refereed]

Adaptive Gait for Large Rough Terrain of a Leg-wheel Robot (First Report : Gait Strategy).

Shuro Nakajima, Eiji Nakano （Part： Lead author )

Journal of Robotics and Mechatronics 20 ( 5 ) 801 - 805 2008 [Refereed]

Free Gait Algorithm with Two Returning Legs of a Leg-Wheel Robot.

Shuro Nakajima, Eiji Nakano, Takayuki Takahashi （Part： Lead author )

Journal of Robotics and Mechatronics 20 ( 4 ) 661 - 668 2008 [Refereed]

Adaptive Gait for a Leg-Wheel Robot Traversing Rough Terrain (Second Report: Step-Up Gait).

Shuro Nakajima, Eiji Nakano （Part： Lead author )

Journal of Robotics and Mechatronics 20 ( 6 ) 912 - 919 2008 [Refereed]

Adaptive Gait for Large Rough Terrain of a Leg-wheel Robot (6th Report, Gait for an Upward Step on Slope)

Shouichi Morimura, Shuro Nakajima, Eiji Nakano

Transactions of the Japan society of mechanical engineers. C ( 日本機械学会 ) vol.73 ( no.732 ) pp.2287-2294 - 1076 2007.08 [Refereed]

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