Tamio Arai

The University of Tokyo, Edo, Tōkyō, Japan

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Publications (141)26.83 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: A cellular manufacturing system is good at producing diversified products flexibly; however, its assembly efficiency depends mainly on its operators' abilities. As the workforce shrinks in Japan, cellular manufacturing systems are difficult to maintain. In this case, a new assembly system has been developed since 2006 that combines both the dexterities of human operators and the advantages of automatic machinery. Its characteristics consist of three aspects: collaboration between an operator and twin manipulators on a mobile base, assembly information guidance, and safe design for collaboration. To meet the rapid changing tastes of customers, operators have to assemble various products without longtime training. This requires an effective assembly skill transfer system to extract assembly skills from skilled operators, and then transfer them to novice ones. Considering the characteristics of a cellular manufacturing system, an assembly skill transfer system was proposed and used to extract and transfer assembly skills in both cognition and execution aspects. Taking a cable harness task as an example, the proposed skill transfer system was applied in a developed assembly system. The results show that working under the developed assembly system with physical support, informational support, and the assembly skill transfer system, novice operators' assembly performance was greatly improved. This verified the effect of the proposed solution to maintain the cellular manufacturing system in the aging Japanese society.
    IEEE Transactions on Automation Science and Engineering 01/2012; 9:31-41. · 1.67 Impact Factor
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    ABSTRACT: A recovery model is proposed to represent the relationship between the muscle fatigue and the rest time. Three experiments were conducted at 50% MVC with the contraction time of 10 s, 30 s and 50 s. Every experiment consists of 5 handgrip tasks with different rest interval. The maximal isometric forces during the pre-fatigue and post-fatigue were recorded to compute the muscle fatigue developed from each handgrip tasks. An exponential function is used to model the relationship between the muscle recovery and rest interval. With this model, the amount of muscle fatigue that is recovered given the rest duration can be estimated. The results suggest that the rate of muscle recovery is correlated to the degree of muscle fatigue at any particular moment, regardless the contraction level or contraction time of the tasks. It is demonstrated that the performance is not significant improved by increasing the number of experiments during calibration process. After that, the recovery model is integrated with the existing fatigue index proposed previously. This is then evaluated on cyclic handgrip tasks. The results show that during the high repetitive motion tasks, the effect of muscle recovery is essential to be taken into consideration for quantifying the degree of muscle fatigue. In average, the estimation error is between 5% MVC, comparing between the estimated value and the force loss measured using dynamometer. This concludes the effectiveness of utilizing force loss as the index to quantify the muscle fatigue and recovery.
    International Journal of Industrial Ergonomics - INT J IND ERGONOMIC. 01/2012;
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    ABSTRACT: This study presents a multiple-goal task realization in a system composed of a 6-d.o.f. robot arm and a one-axis rotating table. The problem is complex due to the existence of multiple goals and the kinematic redundancy of the system. We propose a design approach integrating the base placement, task sequencing and motion coordination methods. We show that this approach reduces the task completion time of the robot arm; the motion planning is realized through straight-line paths in the configuration space despite collision occurrences. Furthermore, we introduce a hybrid graph-search method combining the greedy nearest-neighbor method and the Dijkstra method to solve the motion coordination of the robot arm and the table. We show the effectiveness of the design approach and the search method through a time-constrained simulation-based optimization.
    Advanced Robotics 01/2011; 25:717-738. · 0.51 Impact Factor
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    ABSTRACT: Task completion time and cost are two significant criteria for the selection of manipulator system. For a given task, several Pareto solutions of manipulator systems should be derived based on the evaluation of these two criteria. However, this process requires a large calculation time. In this paper, we propose a method that can select appropriate systems by evaluating task completion time and cost within the desired calculation time. In the proposed method, multiple objective particle swarm optimization (MOPSO) is employed to search for appropriate manipulator systems from a set of candidate systems. Location optimization and motion coordination are integrated to derive the task completion time and the relative cost is used to evaluate the cost of a manipulator system. We employ particle swarm optimization (PSO) for location optimization and use nearest-neighborhood algorithm (NNA) for motion coordination, since PSO and NNA have a high speed of convergence to a good solution. The proposed method is applied to a set of tasks and is proved to be effective and practical.
    2011 IEEE/RSJ International Conference on Intelligent Robots and Systems, IROS 2011, San Francisco, CA, USA, September 25-30, 2011; 01/2011
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    ABSTRACT: Practices of developing applications based on SOA principles need to be renovated to meet new requirements for large-scale data processing and to adapt advancements in IT infrastructures in cloud computing. Resource planners will have a significant role as they bridge the development and operation phases in application development. To accomplish these tasks, this paper presents architecture design methods, which reinforce designing and assessing architecture with an applied Design Structure Matrix (DSM). This approach can embrace development of both business logics of applications and IT resources to run them in the cloud and the methods are established through consulting practices on a datacenter.
    Services (SERVICES), 2011 IEEE World Congress on; 01/2011
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    ABSTRACT: Cellular manufacturing meets the diversified production and quantity requirements flexibly. However, its efficiency mainly depends on the operators' working performance. In order to improve its efficiency, an effective assembly-support system is required to assist operators during the assembly process. In this paper, a multi-modal assembly-support system (MASS) was proposed, which aims to support operators from both informational aspect and physical aspect. To protect operators in MASS system, several safety designs in both hardware and control levels were also discussed. With the informational support and physical support from the MASS system, the assembly complexity and the operators' burden are reduced. To evaluate the effect of MASS, a group of operators were required to execute a cable harness task. From the experimental results, it can be concluded that by using this system, the operators' assembly performance was improved, and the efficiency of the cellular manufacturing was also improved.
    01/2011;
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    ABSTRACT: Evaluating customer satisfaction is a key factor in service design. Therefore, some studies of customer satisfaction have been carried out in the field of service engineering. In these studies, customers’ expectations of service have generally been regarded as being shaped before service delivery. However, expectations of some components of service tend to be formed in the process of service receiving. To analyze service from the view of custoemer satisfaction, expectation that changes while customers are receiving service need to be considered. Therefore, we aim to develop the methodology to support designing services in a way that relates to the formation of customer expectations. In this paper, a model of shaping expectations in service receiving is examined and its effect on customer satisfaction is analyzed.
    01/2011;
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    ABSTRACT: We have presented methods to detect an act of reaching among other hand movements and to predict target objects based on measurements of a user's hand and eye movements. In the detection method, we adopted speed, the smoothness and straightness of a user's hand movements, and the relationship between hand and eye movements. The usefulness of the proposed method was experimentally demonstrated. In the future, an error recovery algorithm should be developed for more reliable deskwork support system.
    09/2010; , ISBN: 978-953-307-062-9
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    ABSTRACT: In this paper, we proposed a step by step approach to planning robot motions for complex assembly tasks. It can be assumed that a complex assembly motion consists of some basic assembly motions, which can be accomplished with fixed force control parameters. Therefore, we firstly proposed an optimization method for basic assembly motions to obtain appropriate force control parameters that can efficiently achieve operations. Based on the results, we then proposed a policy integration method in order to generate complex assembly motions by utilizing optimized basic assembly motions. These methods were applied to clutch assembly in this paper. Using the parameter optimization method, effective policies for insertion and search motions were obtained; and then, a new control policy for clutch assembly was developed by integrating these basic assembly motions. Based on the new policy obtained by the policy integration method, the effective motion was chosen with perceiving the engagement of the clutch hub and the clutch plates. The result shows that the proposed approach makes it possible to generate complex assembly motions that need some switching of force control parameters according to task states. It is one of the future works to develop a learning method in order to efficiently generate a new policy based on similar policies. Although the approach was applied only to the clutch assembly in this paper, it will be applied to the other complex assembly tasks for more evaluation.
    09/2010; , ISBN: 978-953-307-062-9
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    ABSTRACT: The challenge of this work is to develop collaboration planning between human operator and robot system in a collaborative manufacturing system by task analysis approach. The development is worked in parallel with a cable harness assembly operation in a prototype cellular manufacturing system. The core developments of this study are summarized as the following: (a) Task decomposition by hierarchical task analysis ­ by using the capability of HTA, the entire operation is being decomposed into structured hierarchical tasks tree. (b) Collaboration analysis ­ qualitative and quantitative analyses are conducted to identify and justify the possible collaborative solutions from the task model to further define the details of collaboration. Collaboration roles are assigned to all task components with color task role indicators to improve the collaboration relationship representation of the task model. (c) Design enhancements in operation process design ­ improvements in term of (a) group repetitive steps, (b) add interval step, (c) preserve collaboration, and (d) assembly sequence changes are achieved in the task modeling of cable harness assembly. (d) Design extensions in human skill analysis, safety assessment and operation support ­ extensions in facilitate human cognitive and motor skills studies, conduct risk assessment for safety design and assist information support development. (e) Practical implementation in prototype system ­ model validation was conducted successfully with an actual cable harness assembly operation and positive results were obtained in the operation performance evaluation. This work might have completed a preliminary modeling framework for human-robot collaboration planning in manufacturing systems based on task analysis approach. More research studies and developments are needed to further enhance the work: (a) Quantitative studies should be conducted to investigate the effectiveness of the human-robot collaboration planning. (b) Comparison study with other production operations to investigate the modeling capability of the proposed framework. (c) The temporal aspects in collaboration should be taken into consideration to develop a more realistic representation for asynchronous human-robot operations.
    04/2010; , ISBN: 978-953-307-070-4
  • JACIII. 01/2010; 14:758-769.
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    ABSTRACT: This paper addresses the use of a service robot system working for humans in a daily life environment. The robot system described here always interacts with humans, and is therefore required to consider the satisfaction of users to provide suitable services. Our goal is to develop a robot system offering a hand-over service according to the preference of users. Here, we construct a task instruction system for the hand-over task utilizing the idea of Service Engineering as the first step in our research. The system can be used to instruct a robot to bring the indicated objects only by selecting task information, such as grasping position and posture, which can be utilized to estimate the user's preference.
    2010 IEEE/RSJ International Conference on Intelligent Robots and Systems, October 18-22, 2010, Taipei, Taiwan; 01/2010
  • Journal of Robotics and Mechatronics. 01/2010; 22(4):430-438.
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    ABSTRACT: Our research aims to design and develop a safety strategy for a human–robot collaboration system. Although robotic assistance in a cellular manufacturing system is promising, safety is the uppermost consideration before it can be materialized. Five main safety designs are developed in this work. (i) Safe working areas for humans and robots. (ii) To control the behavior of the robot based on the collaboration requirements, light curtains defined safe collaborative working zones. (iii) Additionally, the robot system was developed using safe mechanical design and Dual Check Safety control strategies in terms of robot speed and travel area to minimize collaboration risks. (iv) A vision system using IP cameras was developed to monitor operator safety conditions by measuring the body posture and position of the operator. (v) The operation control system coordinated the collaborative flow between the operator and robot system. Apart from these developments, risk assessments were conducted to evaluate the safety design of the system, and a mental safety study was performed to investigate robot motion speed and working distance on the operator's physiological effects. Our findings demonstrate the feasibility of the prototype system to safely perform assembly operations.
    Advanced Robotics 01/2010; 24:839-860. · 0.51 Impact Factor
  • Ryosuke Chiba, Tamio Arai, Jun Ota
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    ABSTRACT: An integrated design process for automated guided vehicle (AGV) systems is proposed in this paper. There are two problems inherent in the design of systems: transporter routings and flow-path networks. They should both be solved at the same time because one depends on the other. In the present research, this issue is solved through cooperative co-evolution. For the development of co-evolution, some partner selection strategies and some evolving cycles, which are proper for design process, are evaluated. Both the transporter routing problems and the flow-path network problems are represented as different species, and a genetic algorithm is applied to them. AGV systems designed with this method are evaluated through simulations with real data. These simulations show that the proposed method makes it possible to improve the effectiveness of AGV systems.
    Advanced Robotics 01/2010; 24:25-45. · 0.51 Impact Factor
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    ABSTRACT: To classify the five individual finger motions from an electromyogram (EMG) signal, a classification system that hybridizes EMG signals in both the transient and converged states of a motion is proposed. The classifications of finger motions are executed individually in each state by a well-established artificial neural network (ANN). Then, the outputs of the two classifiers are combined. The efficacy of the result is evaluated via a piano-tapping task, in which the subjects are instructed to tap a keyboard with each of their five fingers. We use this task to compare the proposed hybrid system and a conventional converged system that uses an EMG signal only in the converged state. For five of the six subjects, the accuracy ratio of finger motions was better in the proposed method: approximately 85% for each finger except the second. Further analysis suggests two remarkable advantages of the hybrid method: (1) the output of the ANN is more credible, and (2) finger motion in the transient state (i.e., the early phase) is more predictable.
    IEEE International Conference on Robotics and Automation, ICRA 2010, Anchorage, Alaska, USA, 3-7 May 2010; 01/2010
  • Ryu Kato, Marina Fujita, Tamio Arai
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    ABSTRACT: Even if a cellular manufacturing system is robot assisted with assembly support, the main operator is human. A system designer cannot therefore ignore the mental strain experienced by the operator as a result of improper assembly support. In this paper, authors analyzed operators' mental strain induced by physical and informational support in an advanced cellular manufacturing system with human-robot collaboration using physiological parameters related to cognition and emotion. Our results showed that higher speeds of an approaching robot's motion and closer distances between human operator and robot increase mental strain related to emotion, while augmenting text instruction with voice guidance and optical instruction increase mental strain related to cognition and emotion.
    01/2010;
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    ABSTRACT: Design of Redundant Degrees of Freedom in Task Realization of a Robot System with Positioning Errors of Objects
    Journal of Advanced Mechanical Design Systems and Manufacturing 01/2010; 4:1234-1245. · 0.49 Impact Factor
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    ABSTRACT: This paper describes a similarity measure for images which can be used in image-based topological localization and topological SLAM problems by autonomous robots with low computational resources. Instead of storing the images in the robot’s memory, we propose a compact signature to be extracted from the images. The signature is based on the calculation of the 2D Haar Wavelet Transform of the gray-level image and its size is only 170 bytes. We called this signature the DWT-signature. We exploit the frequency and space localization property of the wavelet transform to match the images grabbed by the perspective camera mounted on board the robot and the reference panoramic images built using an automatic image stitching procedure. The proposed signature allows, at the same time, memory saving and fast and efficient similarity calculation. For the topological SLAM problem we also present a simple implementation of a loop-closure detection based on the proposed signature.We report experiments showing the effectiveness of the proposed image similarity measure using two kinds of small robots: an AIBO ERS-7 robot of the RoboCup Araibo Team of the University of Tokyo and a Kondo KHR-1HV humanoid robot of the IAS-Lab of the University of Padua.
    Robotics and Autonomous Systems. 01/2010;
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    ABSTRACT: In this paper, we propose a force estimation model to compute the handgrip force from SEMG signal during fatiguing muscle contraction tasks. The appropriate frequency range was analyzed using various combinations of a wavelet scale, and the highest accuracy was achieved at a range from 242 to 365 Hz. After that, eight healthy individuals performed a series of static (70%, 50%, 30%, and 20% MVC) and dynamic (0-50% MVC) muscle contraction tasks to evaluate the performance of this technique in comparison with that of former method using the Root Mean Square of the SEMG signal. Both methods had comparable results at the beginning of the experiments, before the onset of muscle fatigue. However, differences were clearly observed as the degree of muscle fatigue began to increase toward the endurance time. Under this condition, the estimated handgrip force using the proposed method improved from 17% to 134% for static contraction tasks and 40% for dynamic contraction tasks. This study overcomes the limitation of the former method during fatiguing muscle contraction tasks and, therefore, unlocks the potential of utilizing the SEMG signal as an indirect force estimation method for various applications.
    Journal of electromyography and kinesiology: official journal of the International Society of Electrophysiological Kinesiology 10/2009; 20(5):888-95. · 2.00 Impact Factor

Publication Stats

540 Citations
26.83 Total Impact Points

Institutions

  • 1996–2012
    • The University of Tokyo
      • • Department of Precision Engineering
      • • Faculty & Graduate School of Engineering
      Edo, Tōkyō, Japan
  • 2010
    • University of Padova
      • Department of Information Engineering
      Padova, Veneto, Italy
  • 2009
    • Chiba University
      • Department of Medical System Engineering
      Chiba-shi, Chiba-ken, Japan
  • 2007
    • NEC Corporation
      Edo, Tōkyō, Japan
  • 2006
    • Yokohama National University
      • Department of Physics, Electrical and Computer Engineering
      Yokohama, Kanagawa, Japan