Journal of Robotics and Mechatronics
Online ISSN : 1883-8049
Print ISSN : 0915-3942
ISSN-L : 0915-3942
Volume 27, Issue 3
Displaying 1-10 of 10 articles from this issue
Regular papers
  • Ronnapee Chaichaowarat, Witaya Wannasuphoprasit
    Article type: Paper
    2015 Volume 27 Issue 3 Pages 225-234
    Published: June 20, 2015
    Released on J-STAGE: July 01, 2019
    JOURNAL OPEN ACCESS

    Drifting is a large sideslip cornering technique with counter steering, which is advantageous in some driving conditions where vehicle-handling capability over linear tire slip-friction characteristics is imperative. In this paper, the dynamics of a rear-wheel-drive (RWD) vehicle cornering at steady states was simplified using a single-track vehicle model. In addition, tire frictions in any slip conditions were estimated from the combination of the Pacejka’s magic formula and the modified Nicolas-Comstock tire model. A computer program was developed, on the basis of the equations of motion (EOMs) derived via the body-fixed coordinate so that the suitable cornering speed and its corresponding steady-state driving control inputs (the steering angle and rear wheel slip ratio) could be calculated automatically for any given radius of curvature and vehicle sideslip. The other set of EOMs was derived via the normal-tangential coordinate and then linearized so that the state space description could be constructed. Eventually, the linear quadratic optimal regulator was designed and simulated via MATLAB for various regulation problems where the initial condition of each individual state deviated from its desired steady-state value. According to the simulation results, the physical explanation of the control inputs can be used as guidance for adjusting vehicle behavior in manual driving.

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  • Maxime Boisvert, Philippe Micheau, Didier Mammosser
    Article type: Paper
    2015 Volume 27 Issue 3 Pages 235-243
    Published: June 20, 2015
    Released on J-STAGE: July 01, 2019
    JOURNAL OPEN ACCESS

    A three-wheel hybrid recreational vehicle was studied for the purpose of regenerative braking control. In order to optimize the amount of energy recovered from electrical braking, most of the existing literature presents optimal methods which consist in defining the optimal braking torque as a function of vehicle speed. The originality of the present study is to propose a new strategy based on the control of rear wheel slip. A simulator based on MATLAB/Simulink and validated with experimental measurements compared the two strategies and their sensitivities to variations in mass, slope and road conditions. Numerical simulations and experimental tests show that regenerative braking based on a slip controller was less affected by the majority of the parametric changes. Moreover, since the slip was limited, the longitudinal stability of the vehicle was thereby improved. It thus becomes possible to ensure optimal energy recovery and vehicle stability even in instances of parametric uncertainties.

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  • Guimei Gu, Rang Hu, Yuanyuan Li
    Article type: Paper
    2015 Volume 27 Issue 3 Pages 244-250
    Published: June 20, 2015
    Released on J-STAGE: July 01, 2019
    JOURNAL OPEN ACCESS

    In order to identify two failures of crack damage and edge damage to wind turbine blade, a damage identification system was designed by acoustic emission technique. This system took advantage of wireless technique for signal collection and transmission and upper computer for receiving and processing data. This system adopted acoustic emission sensor, NRF905 wireless transmission, upper computer designed by VB language, and the serial communication function of VB for data receiving. Data was firstly normalized after being received. Then, the energy features of data were abstracted by db wavelet. With the abstracted features, support vector machine model was established and verified, and the machine parameters were optimized by particle swarm optimization. Results show that the system is reliable in data collection and transmission, and the correctness of damage identification obviously increases by optimizing the support vector machine with particle swarm. The design provides method to monitor the status of rotating object, so this system can provide model base for subsequent studies.

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  • Nagisa Koyama, Shuhei Ikemoto, Koh Hosoda
    Article type: Paper
    2015 Volume 27 Issue 3 Pages 251-258
    Published: June 20, 2015
    Released on J-STAGE: July 01, 2019
    JOURNAL OPEN ACCESS

    Stochastic resonance (SR) is a phenomenon by which the addition of random noise improves the detection of weak signals. Thus far, this phenomenon has been extensively studied with the aim of improving sensor sensitivity in various fields of engineering research. However, the possibility of actual application of SR has not been explored because the target signal has to be known in order to confirm the occurrence of SR. In this paper, we propose an optimization method for making SR usable in engineering applications. The underlying mechanism of the proposed method is investigated using information theory and numerical simulation. We developed a tactile sensing system based on the simulation results. The proposed method is applied to this system in order to optimize its parameters for exploiting SR. Results of the experiment show that the developed tactile sensing system successfully achieved higher sensitivity than a conventional system.

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  • Yuuka Irie, Shinnosuke Hirata, Chisato Kanamori, Hisayuki Aoyama
    Article type: Paper
    2015 Volume 27 Issue 3 Pages 259-266
    Published: June 20, 2015
    Released on J-STAGE: July 01, 2019
    JOURNAL OPEN ACCESS

    Recently, micro-droplet dispensation has been required in printed-electronics (PE) technology. Devices with micro dispensing mechanism are of key importance in achieving a higher performance with these products. In fact, it is very difficult for the conventional dispenser to squeeze highly viscous liquid with picoliter resolution. This paper describes the development of a dispensing mechanism comprising a dispensing device and XY stage, both driven by the piezo impulsive force. The dispensing device is mainly composed of a pipette and a taper needle that is driven by a piezoelectric element. When the needle passes through the pipette, a droplet of the liquid adheres to the needle-tip end. A micro droplet can be transcribed to a target surface by bringing the droplet at the needle-tip end in contact with the target surface. On the contrary, in the XY stage, the small tables on the V-shaped grooves can be driven by the impulsive force generated by the mass connected to the piezoelectric element. The X stage is stacked on the Y stage, which allows fine positioning in the plane. In the experiment, an array of a small amount of 0.2-picoliter droplets was successfully developed on the glass plate.

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  • Jumpei Arata, Yuji Isogai, Junya Sumida, Masamichi Sakaguchi, Ryu Naka ...
    Article type: Paper
    2015 Volume 27 Issue 3 Pages 267-275
    Published: June 20, 2015
    Released on J-STAGE: July 01, 2019
    JOURNAL OPEN ACCESS

    Robotic instruments have recently been widely introduced into industrial automation. As energy supply and demand have become global issues, energy saving in industrial robots has become urgent. In general industrial pick-and-place robots, servomotors periodically repeat acceleration and deceleration, consequently lose much energy in motion. We propose a mechanism using an in-frame parallel spring for the pick-and-place robot. During motion, spring blades deform and store energy, then release it as energy of motion, enabling the mechanism to recycle energy that have been lost in conventional mechanisms. In this paper, a 1 DOF proof-of-concept prototype and preliminary feasibility tests are described. In this study, we applied in-frame parallel springs to a mechanism for pick-and-place robot. The parallel springs are fabricated from spring steel SK85M (Young’s modulus: 210 GPa) with 252 mm long, 50 mm wide and 0.3 mm thick. The results suggest that the prototype can achieve a repeated motion with the range of ±145.7 mm in 2.56 Hz by 1.17 W, greatly reduced from that of the the traditional mechanisms. In addition, it is desired to stop the robot immediately in regular motion if anomalies occurred in industrial applications. The prototype showed that an immediate stop in 0.6 s was feasible by dissipating elastic energy stored in spring blades, confirming the feasibility of our proposed mechanism.

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  • Shunon Kikuchi, Yasuyuki Yamada, Ryoichi Higashi, Toshio Morita
    Article type: Paper
    2015 Volume 27 Issue 3 Pages 276-285
    Published: June 20, 2015
    Released on J-STAGE: July 01, 2019
    JOURNAL OPEN ACCESS

    The new super multi-joint manipulator mechanism we introduce in this paper is constructed from a long flexible resinous plate in the center of the manipulator and a pneumatic actuator the same length as the arm arranged antagonistically. The number of power transmission mechanism is fewer than that of joints. Specialized in a winding grip, the mechanism is light and simple. From the effect of this property, the manipulator could be easily extended in the length. The experimental mechanism mode was developed and several experiments were conducted, such as driving on the vertical plane, grasping some objects and moving with flow rate adjustment. As a result, the manipulator could drive on the vertical plane, winds cylinders of 50–200 mm in diameter and controls winding behavior.

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  • Kentaro Ueno, Tetsuo Kinoshita, Kazuyuki Kobayashi, Kajiro Watanabe
    Article type: Paper
    2015 Volume 27 Issue 3 Pages 286-292
    Published: June 20, 2015
    Released on J-STAGE: July 01, 2019
    JOURNAL OPEN ACCESS

    In this paper, we describe the development of a robust path planning algorithm for an autonomous mobile robot. In order to achieve safe navigation in areas with moving obstacles, the mobile robot has to be controlled by a dynamic path-planning algorithm to avoid collisions. However, depending on changes in obstacle positions, the dynamic path planning algorithm frequently faces path-switching problems. In order to avoid the path-switching problems in the dynamic path planning algorithm, we introduce a virtual obstacle assignment method to suppress events caused by the path-switching problems. The effectiveness of proposed method is proved by an actual mobile robot. The validity of proposed method is confirmed by both simulations and actual outdoor experiments.

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  • Kousuke Inoue, Tamio Arai, Jun Ota
    Article type: Paper
    2015 Volume 27 Issue 3 Pages 293-304
    Published: June 20, 2015
    Released on J-STAGE: July 01, 2019
    JOURNAL OPEN ACCESS

    In this paper, we propose a method by which an agent can autonomously construct a state-representation to achieve state-identification with a sufficient Markovian property. Furthermore, the agent does this using continuous and multi-dimensional observation-space in partially observable environments. In order to deal with the non-Markovian property of the environment, a state-representation of a decision tree structure based on past observations and actions is used. This representation is gradually segmented to achieve appropriate state-distinction. Because the observation-space of the agent is not segmented in advance, the agent has to determine the cause of its state-representation insufficiency: (1) insufficient observation-space segmentation, or (2) perceptual aliasing. In the proposed method, the cause is determined using a statistical analysis of past experiences, and the method of state-segmentation is decided based on this cause. Results of simulations in two-dimensional grid-environments and experiments with real mobile robot navigating in two-dimensional continuous workspace show that an agent can successfully acquire navigation behaviors with many hidden states.

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  • Kazuto Miyawaki
    Article type: Development Report
    2015 Volume 27 Issue 3 Pages 305
    Published: June 20, 2015
    Released on J-STAGE: July 01, 2019
    JOURNAL OPEN ACCESS

    Medical and nursing care of the elderly is becoming a significant social burden. Welfare equipment is also being developed to help the elderly use their potential. Against this background, we developed a power assist chair for helping the elderly live life as independently as possible.

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