This paper proposes a method for simultaneous laser energy transmission and motion control of micro vehicles. Both the energy transmission and the remote control are achieved simultaneously with the same light path of two lasers. A green laser and a laser diode are used independently for the navigation and the energy transmission, respectively. Core technology of the system is the laser tracking, in which the direction of the tracking laser beam is changed by a galvano mirror so as to keep chasing the position of the corner-cube reflector mounted on the vehicle. In addition, by using a pulsing oscillation of the tracking laser, the vehicle is able to receive operation commands as a frequency change of the pulse. A beam of the laser diode runs parallel to the tracking beam and is radiated to the solar cells mounted on the vehicle. Then the photoelectrically converted power is supplied for the DC motors and control circuits on the vehicle. Experiments with a small wheeled-vehicle were conducted, and the results show that proposed system exhibits sufficient performance for controlling and supplying power to the micro vehicle.

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As heavy haul trains continue to push the limits of train size and mass and maximise locomotive performance, improving control of adhesion and slip will continue to be in demand. In considering the need to realise maximum adhesion forces for a rail vehicle, it is important to provide the development of new algorithms for traction control in a proper way that takes into account the need to avoid rail and track damage. This paper presents a strategy based on the Polach contact model for the detection of maximum adhesion force, and this strategy also includes slip compensation. The proposed traction control system has been verified by means of a co-simulation approach between the Gensys multibody code and the Simulink package.

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A flux-path control magnetic suspension system with multiple magnetic sources is realized. The principle of the flux-path control magnetic suspension system is to control flux from a permanent magnet to the floator, and the attractive force acting on the floator by the motion control of control plates inserted between the permanent magnet and the floator. Stable suspension and 3-DOF control with a single magnetic source was achieved. However, the horizontal control force was much less than the vertical control force. Multiple magnetic source system can overcome such problem. A variable flux-path unit is developed for the realization of multiple magnetic source system. An experimental apparatus with two variable flux-path units is constructed. Stable levitation is achieved by applying PD and PID controls. In addition, stable levitation with zero-power control is also achieved.

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This paper proposes a vibration suppression mechanism consisting of permanent magnets, actuators, sensors and a controller. The aim of this proposed system is to reduce vibration and/or deformation of thin steel sheets by controlling the air-gap between the permanent magnets and the steel sheets. The feedback control of the system was designed by means of the LQR method. In this study, the proposed vibration suppression mechanism was designed, the prototype was constructed for experimental confirmations, feasibility of the model of prototype and the design of the controller was analyzed, and numerical simulations and experimental examinations were carried out to verify the effectiveness of the controller designed by LQR method. The simulations and experiments were performed under initial disturbance conditions with PD control and without PD control. All results verified that the system effectively suppressed vibration.

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The purpose of our study is to develop a small-sized, lightweight, lower energy consumption and flexible control valve that can be safe enough to mount on the human body. In our previous study, the control valve that could open using a vibration motor was proposed and tested. A new type of fluid control valve with a self-holding function using a permanent magnetic ball in a check valve, a cylindrical magnet and two solenoids was also proposed and tested. In this study, we propose and improve the valve so as to make a 2-position 3-port control valve with a self-holding function. As a result, we confirm that the tested valve can realize both functions of supply and exhaust. We also find that the valve has an overlap function by using the time lag of moving a cylindrical magnet. In addition, a digital servo valve with self-holding function is also proposed and tested. As a result, we can confirm that the tested digital servo valve can control output flow rate in both supply and exhaust.

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Based on two-dimensional (2-D) system theory, this study proposes a design method for a filter-based iterative learning control (FILC) scheme. The FILC scheme consists of a proportional feedback controller and a feedforward filter. The 2-D model for the FILC is established in the form of the so-called “Roessor's model”. Moreover, stability for a 2-D separable model can be simplified, with only one criterion to be met. In order to utilize the criterion derived from the 2-D separable system, the overall FILC control system is constructed in the form of a 2-D separable system by assuming a new state for the 2-D model. Therefore, a sufficient and necessary condition for convergence of the overall control system can be reached. Moreover, to validate the design criteria, we establish design criteria for the feedforward filter and conduct a simulation. Finally, the proposed scheme is applied to the force tracking of a lower-limb orthosis with pneumatic muscle actuator (PMA). Excellent force-tracking performance is achieved through experimental verification.

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In this paper, we give the parameterization of all stabilizing modified repetitive controllers for multiple-input/multiple-output plants. The basic idea to obtain the parameterization of all stabilizing modified repetitive controllers for multiple-input/multiple-output plants is very simple. If the modified repetitive controller stabilizes the plant, then the modified repetitive controller must be included in the class of all stabilizing controllers for the plant. The parameterization of all stabilizing controllers for the plant, which is not necessarily modified repetitive controllers, is obtained using the method by Youla et al. and Vidyasagar. The parameterization of all stabilizing controllers includes free parameter, which is stable. Stabilizing modified repetitive controllers for multiple-input/multiple-output systems can be designed using the free parameter in the parameterization. Using this idea, we obtain the parameterization of all stabilizing modified repetitive controllers for multiple-input/multiple-output plants.

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We have developed an analysis and synthesis method for mixed-sensitivity problems in sampled-data positioning control systems. The method uses frequency responses of the controlled object and the digital controller for calculating the characteristics of the control system without complicated calculations involving matrices. Our proposed method indicates relationships between the sensitivity function and complementary sensitivity function for the mixed sensitivity problem in a sampled-data positioning control system. We also address the mixed sensitivity problem for multi-rate control systems that include an interpolator, a multi-rate filter, and a multi-rate hold. To show the validity of the proposed method, we conducted simulations and experiments on the sampled-data positioning control system of a head-positioning control system in a hard disk drive. These results show that control engineers should know the difference between the discrete-time control system and the sampled-data control system even for frequencies below the Nyquist frequency.

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This study introduces a form of vision-based machinery surveillance for abnormal behavior detection in high-speed periodic operation. This new surveillance method includes high-frame-rate (HFR) video logging with a phase encoding algorithm (for use with periodic operation) to efficiently match input images with pre-stored reference images. To allow periodic machinery operations to be monitored, the surveillance algorithm can estimate the phase of a periodic operation by inspecting temporal changes in the brightness at several significant pixels in an input image from a single camera; abnormal behavior in periodic operation can be intelligently detected at a crucial moment by comparing the input image with the reference image synchronized with its encoded phase without the heavy computation required to search all the reference images for the matching process. This algorithm was implemented by software on a high-speed vision platform, IDP Express, which can record input images of 512 × 512 pixels and processed results at 1000 fps for video logging. We verified the effectiveness of the HFR-video-based machinery surveillance by performing two on-line experiments for high-speed periodic operation at dozens of hertz using a sewing machine.

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The purpose of this study is to propose a nonlinear viscoelastic model for sports surfaces and an identification method of this model. Although various models have been proposed to represent the behavior of rubber materials, some models represent only the material's elastic behavior, while other models deal with viscoelastic behavior but have problems in the computer simulation of that behavior. The model proposed in this study can represent viscoelastic behavior well and also has stability of computer simulation. In the identification methods, four types of drop weights, which have different mass and damping material for producing a wide range of impact durations and impact intensities, are used for impact tests. The impact force, velocity and deformation are measured in each impact test, the parameters of the elastic element of the model are calculated by the least squares method and then the parameters of the viscous element of the model are calculated from the experimental force and the estimated force produced by the elastic element. The model proposed in this study has high identification accuracy and stability of simulation compared to previous models.

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This paper experimentally examines effects of stable nonlinear normal modes on self-synchronized phenomena by using oscillators that are excited by intermittent electromagnetic power. The oscillator behaves as a pendulum-type oscillator when the applied voltage is low whereas as a rotor-type oscillator when the voltage is high. Stable nonlinear normal modes are obtained numerically by modified shooting method. Experimental and analytical results demonstrate that self-synchronized phenomena of pendulum-type oscillators as well as rotor-type oscillators can be explained well by using stable nonlinear normal modes of the system.

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This paper is concerned with an active wave control method of a rectangular panel. It is the purpose of this paper to present a wave filtering method for the panel using smart modal sensors and its application to an adaptive feedforward control system. Firstly, a wave solution of a rectangular panel is derived to describe the wave dynamics of the structure. This is followed by the proposition of the design procedure of the wave filter using smart mode sensors. Then, from a viewpoint of numerical analyses, accuracy of the proposed method is verified using condition numbers of a filtering matrix. Furthermore, a multi-rate technique, which reduces the computational burden, is introduced for approximation of the sub-filters in the wave filter. Finally, experiment on an adaptive feedforward control system using the proposed method is carried out. It is found that the reflected wave absorbing control enables the inactivation of vibration modes.

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The hand-arm vibration syndrome characterized by Raynaud's disease is caused by long-term use of hand-held vibrating tools. The purpose of the present research is to develop a new vibrating tool using self-synchronization phenomena in order to reduce hand-arm vibration. In the present paper, an elementary model with a generation mechanism of synchronous vibration suitable for a tamping rammer used to compact cohesive soils on the ground is developed. This model consists of upper and lower blocks coupled by coil-springs, and two rotor-type oscillators are mounted individually on the lower blocks. The nonlinearity due to the impact behavior between the lower block and the ground is approximated by piecewise linear characteristics. The synchronized solutions and the stability are analyzed by applying the improved shooting method for impact vibration analysis. Analytical and experimental results confirm that stable synchronized solutions which are able to achieve a good balance between vibration control and excitation exist. In addition, it is proven that the existence region of the stable solutions can be expanded by setting the system parameters appropriately.

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The FDC (Flow Dynamics Conveyer) has been often used in power plants and iron works because of superiority in quiet compared with a roller type conveyer and it is excellent in a low noise and low power. The FDC consists of a trough and a belt, and the air is supplied from a lot of holes provided on the trough. However, large vibrations occur when the flow rate becomes a certain value. This abnormal vibration is considered to be self-excited vibration caused by leakage flow induced vibration here. It is well known that the abnormal vibration occurs when the tapered flow channel is formed. The purpose of this study is to clarify the generation mechanism of the abnormal vibration. The experiment was carried out to examine the effect of various parameters such as taper angle θ, floating amount H on the abnormal vibration. As a result, the damping ability becomes small with increase in the taper angle and decrease in the floating amount. Furthermore it was clarified that the abnormal vibration occurs for θ>αH (α:constant value).

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A pressure wave propagating in a tube often changes to a shock wave because of the nonlinear effects in the propagation medium. The purpose of this study is to establish a practical analytical model of this phenomenon. In previous reports, a concentrated mass model was proposed to analyze nonlinear pressure wave phenomena in a rigid straight cylindrical pipe. In this paper, we apply the model to an elastic pipe. The model of the elastic pipe consists of masses, nonlinear connecting springs, base support dampers, base support springs, and connecting dampers. The effect that the cross-sectional area of the elastic pipe changes is taken into account through the nonlinear connecting spring. To confirm the validity of the proposed elastic pipe model, we perform experiments on a silicone pipe, and the experimental results are compared with the numerical results obtained by the concentrated mass model. The numerical computational results agree well with the experimental results. Therefore, it is concluded that the proposed elastic pipe model is valid for the numerical analysis of nonlinear pressure wave problems in an elastic pipe.

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