In recent years, demands for tactile sensors for robots have been increasing in the industrial and medical fields. Therefore, in our previous work, we have developed a micro tactile sensor with micro-cantilevers as a detection part of contact force. Micro-cantilevers are fabricated based on technologies of microelectromechanical systems (MEMS). In this research, in order to improve the durability of the micro tactile sensor, the wiring connection was protected by using UV curable resin with much-higher hardness than the conventional silicone elastomer. The response of the sensor with UV curable resin to normal force and durability of wiring connection were compared with the previous sensor without the resin. In the measurement for characterization of force response, there was almost no difference in the sensitivities between the sensor with and without UV curable resin, and it was found that the protective resin for the wiring connection has almost no effect on the sensor output. In the durability test of wiring connection, the previous sensor without the resin protection showed a significant decrease in resistance due to short-circuits when an excessive load was applied. On the other hand, the sensor with the resin protection did not show a significant decrease in resistance. Therefore, it was found that the sensor protected the wiring connection with UV curable resin has higher durability than without the resin.

Automated driving in train is discussing about partially implementation. Those implementations in limited area and situation marked well progress such as general railway lines and AGT. Tram vehicle on mixture traffic seems to be next target of them. Usual automated driving train is controlled considering with velocity and displacement as a position. However, tram vehicle run in the more complex situation than usual automated driving trains. Thus, there are much possibility braking to avoid collision with other traffic participants. In this time, the comfortability of passengers is decreasing if the huge braking acceleration occurring since acceleration is strongly relationship with it. Thus, Automated driving tram should be considered to control with acceleration to let acceleration smaller to improve passenger comfort. So, both displacement and acceleration feedback control are required. However, direct acceleration feedback should consider drift or noise on sensing results. This paper introduces direct acceleration feedback control with direct displacement control for positioning. These controllers are designed by Unified approach and Composite Filter. These controllers are considering with noise reduction for accelerometer. The example controller designed for small experimental rig on the rail are introduced with numerical simulation results. These results show the controllers can set desired poles related with settling time without considering of noise reduction frequency.

In this study, we propose a design method of semi-active control systems by using a variable inertia mass damper (IMD) for structural systems subject to seismic disturbances. The variable IMD is a semi-active vibration control device whose inertia mass coefficient can be changed by a command signal in a real time manner. The mathematical model of the variable IMD is obtained by considering the dynamic delay of the variable inertia mass coefficient subject to change of the command signal. The delay is modeled as a 1st order lag system. For the mathematical model of the structural system with the variable IMD, a semi-active control law that generates the command signal to change the inertia mass coefficient is proposed. It is based on the reference active control output and referred to as the output emulation approach (Hiramoto et al., 2016). The reference active control system is a virtual system obtained by assuming installation of a force actuator on the structural system instead of the semi-active control device. In the output emulation approach, the variable inertia mass coefficient of the variable IMD is changed so that the predicted control output of the semi-active control system becomes close to that of the reference active control system. The optimal set of design parameters in obtaining the active control law for the reference active control system is searched. A simulation study for a 3-dof model of the existing benchmark building shows the effectiveness of the proposed semi-active control method with the variable IMD.

A 2:1 roping elevator system shows a complicated vibration behavior under a disturbance from the traction motor, because the disturbance does not only cause a vertical vibration to the elevator, but also induces a rotational vibration against a suspension sheave of the elevator. As the rotational vibration affects the vertical vibration of the elevator car, an analytical model of the elevator system is introduced to evaluate the relation between the vertical vibration and the rotational one. With the derived analytical model, an eigen mode analysis and a transient time analysis show the mechanism of the rotational vibration under several conditions, such as a car position and a building height.

Because the demand for advanced product design in transportation machines such as automobiles, railways, and aircraft are increasing, there is a strong desire to improve quality from the psychological point of view of a passenger, such as mental stress and physical ride comfort. Degradation of ride comfort in transport machines has various influences such as vibration, noise, and ambient temperature, but there are also survey results which show that vibration affects comfort, especially in trains. In this paper, as a fundamental study on masking, we verified its effect using the vibration test by simulating the vibration environment applying the masking. From these investigations, we clarify the influence of masking in vertical vibration on the comfort of riders and present the prospects for the design of a new ride comfort control system.

To reduce collision shock and injury risk to an infant in an in-car crib (or in a child safety bed) during a car crash, the force acting on the crib must remain constant below a certain allowable value. Hence, we propose a semi-active in-car crib with joint application of regular and inverted pendulum mechanisms. The crib is supported by arms, like a pendulum; and the pendulum system is supported by arms, like an inverted pendulum. The friction torques of the joints are semi-active controlled using a brake mechanism, which enable the proposed in-car crib to gradually increase the deceleration of the crib and maintain it at approximately the target value, i.e., the large collision force is reduced to the target value. However, a collision impact is directed toward the infant’s side in the crib, and the resulting motion of the body is relatively complex. Therefore, the proposed in-car crib is designed to not only reduce the impulsive force, but also to transfer the force to the infant’s back using a spin control system, i.e., the impulse force acts perpendicularly on the crib. In this study, the spin control system of the crib is derived and applied to the acceleration control system reducing the impulse force. The objective of the spin control system is to suppress the acceleration parallel to the crib floor by rotating the crib. Finally, the effectiveness of the proposed system is demonstrated using numerical simulations.

The purpose of this study is to reduce the response at appropriate timing by applying the control force only when the absolute acceleration of the upper building and the relative displacement of the base isolation layer are satisfied, considering the effect of the building on the ground motion, and to further reduce the total energy consumption.

The acceleration response spectrum is taken from the acceleration data sent to the building. In this study, the area is calculated from the acceleration response spectrum under a predetermined condition. The control force is changed by reflecting the necessary parameters in the LQR method calculated in advance from the area.

A semi-active model that uses two input waves reduces the absolute acceleration of the upper building or the relative displacement of the seismic isolation layer in some time compared with the passive model, according to the variables calculated from the acceleration response spectrum.

The largest variable calculated in the Semi-active model is compared with the Full-active model by the constant control gain calculated by increasing the LQR parameter, and the same variable gives the same control force and reduces the same response at the calculated time. Furthermore, the reduction amount of the control force was greatly reduced by comparing the RMS value of the control force with the RMS value of each response.

Compared with the Passive model, the Semi-active model showed that the desired response can be reduced only for intended time. Furthermore, it was shown that there is almost no difference in the response reduction effect even when compared with the Full-active model in which the control force is continuously applied at the maximum control gain obtained with the Semi-active model. The RMS value also showed that the energy consumption was reduced relative to the response reduction amount.

Ultra-compact EVs are becoming increasingly popular recently. Therefore, it is important to provide ride comfort for a driver to advance the high-value-adds of automobiles. However, one of the problems for the ultra-compact EV, an interior noise caused by road and wind noise have a large impact on user comfort in the interior space. Especially, the noise reduction of low frequency noise like a load noise is difficult by passive noise reduction technique using noise reduction material. Therefore, the use of interior noise reduction by active noise control (ANC) has been widely performed in the automobile industry. We proposed ANC system whereby a giant magnetostrictive actuator which is one of small actuator is installed on the roof of the ultra-compact EV. In this paper, we conducted a noise reduction experiment installed the giant magnetostrictive actuator on plate shaped part of the ultra-compact EV by using single-frequency sound waves in the frequency range of the road noise. In addition, we investigated the installation position of the giant magnetostrictive actuator considering the vibration characteristics of the roof to improve the noise reduction effect. From these results, we considered that it is necessary to change the installation position of the actuator according to the output frequency. Furthermore, we proved that it is important to consider the vibration characteristics of the plate shaped part on the actuator to obtain a high noise reduction effect.

The objective of this study is to analyze the transient response of a system with a nonlinear spring under Gaussian white noise excitation using a complex fractional moment (CFM). The CFM is defined by extending an order of a classical integer-order moment to a complex number, and is related to the Mellin transform of a probability density function. In order to find the transient probability density function of the response, first, we linearize an equation of motion by introducing the effective natural frequency, which is the functions of the response amplitude. Secondly, the Fokker-Planck equation for the response amplitude is derived based on the stochastic averaging procedure. Thirdly, the governing equations of the response CFMs are obtained by applying the Mellin transform to the Fokker-Planck equation. The governing equations are easily solved since they are coupled linear ordinary differential equations. Finally, the inverse Mellin transform of the response CFMs yields the probability density function of the response. In numerical examples, we analyze a Duffing oscillator with different two values of a nonlinear parameter and the results are compared with the results of Monte Carlo simulation. Except for a few cases, the present solutions are in good agreement in the wide range including the tail region. We also consider the relation between the accuracy of the analytical result and the choice of the analytical parameters.

Energy harvesting from human motion is expected to the energy source for wearable devices. Although the energy density of human motion is high, the frequency of it is a few Hz, which does not match the conventional energy harvester. Due to this, the size of harvester tends to become large in order to get high output. This paper presents an electrostatic induction energy harvester which can generate high power at low frequency in order to power the mouthguard type sensor. To embed into the mouthguard type sensor, the total thickness of the harvester should be less than 0.2 mm to reduce the discomfort. Furthermore, the final goal of power generated of the harvester was set to a few tens of μW. The proposed harvester consists of electrets that can hold a quasipermanent charge on its surface, dielectric elastomers and electrodes. The mechanical energy applied by the biting force is converted to electrical energy by electrostatic induction. The parametric study of the harvester based on the equivalent circuit model was conducted to maximize the power generated. According to the calculation results, the harvester can achieve 22.7 μW with a load resistance of 570 MΩ, which met the requirements for the mouthguard type sensors. The fabrication and evaluation of the harvester based on the calculation results will be conducted in the future work.

This paper presents lane changing and merging support system with adaptive cruise control (ACC). In lane changing and merging, drivers consider about safety and longitudinal ride comfort. In addition, drivers must finish merging in the acceleration lane. In order to achieve these objectives, we propose the merging decision and control method. The merging decision calculates several plans to merge in the acceleration lane, and selects the plan with smallest acceleration. 2 degree of freedom (2DOF) control is applied to the longitudinal and lateral control. In 2DOF control, the response is defined by the filter. The filter of the longitudinal control defines the reference distance for safe spacing to the surrounding vehicle, and the filter of the lateral control defines the reference path for changing lanes. The longitudinal and lateral control follows these references by the feedback controller and the feedforward controller. The performance of the proposed system is tested by simulations. In these simulations, the merging decision calculates the plan to finish merging in the acceleration lane with the smallest acceleration, and the longitudinal and lateral controller follows references accurately by the feedforward controller. These results show that the proposed system contributes the safe and comfortable lane changing and merging.

In satellites, micro mechanical vibrations generated by mechanical parts such as mechanical cryocoolers and reaction wheels have become a problem. It has been pointed out that these vibrations lead to a decrease in pointing accuracy, and the vibration energy becomes heat, which reduces the cooling efficiency of the cryocoolers. For this problem, active control is required to suppress vibration by applying a control signal to a mechanical actuator that generates vibration. Based on the fact that vibration has a periodic signal and applied a control method using repetitive control. In repetitive control, it is essential to design a filter that compensates for amplitude and phase in order to ensure stability. In this paper, on the assumption that frequency characteristics are estimated online in advance, we proposed a filter design method for designing robust and stable gains based on the estimation results. It is assumed that the plant model obtained by the estimation includes modeling errors and the influence of harmonics due to nonlinear components. The proposed method not only simply solves the inverse model characteristics of the plant, but also considers the interference between harmonic disturbances due to nonlinearity and modeling error, by designing the gain, stable control can be achieved robustly.

With the purpose of improving the capacity of energy harvesting, the nonlinear system has better advantages in terms of the effectively operational bandwidth, especially by considering the effect of centrifugal effect, and the bandwidth of the sustainable harvesting can be further expanded. However, the different centrifugal distances of the installation position have different effects for stabilizing the high-energy orbit oscillation, and the optimal installation centrifugal depends on the variety of the corresponding physical characteristics. Therefore, in this paper, the relationship of nonlinear-frequency-matching between the jump-down frequency of monostable state and the rotating frequency of external circumstance are utilized to theoretically solve the optimal location distance for different parameters. The simulation result of velocity responses demonstrates that the solution of optimal centrifugal distance is verified for effectively broadening the frequency range of energy harvesting.

Deep learning is emerging in various areas such as structural noise and vibration problems. In this study, feasibility whether a deep learning model can exactly represent the transfer function of a structure is tested especially in viewpoint of training dada and model structure. For the feasibility test, a transfer path analysis model using an artificial neural network structure was developed and trained with various augmented data as well as original input/output responses. The original input/output responses were collected from a finite element model of a test structure in the frequency domain. By changing the reference phase and by multiplying the complex conjugate of the input and output responses to the input/output pairs, the collected data was augmented. Comparing the performance of the trained deep learning model with classic transfer path analysis model, to correctly represent the contribution of each input to output response it is essential that the phase and the crossspectrum augmented should be included during the deep learning model training process.

This paper discusses the basic study on a cryogenic pump with active magnetic bearings (AMBs) which works in liquid nitrogen (-196 degrees centigrade). The cryogenic pump is composed of two AMBs, four displacement sensors, a permanent magnet (PM) motor, turbine blades, etc. In order to check the passive stability for the rotor, impulse responses for the levitated rotor in the axial direction are performed. The pump flow is measured in the speed range from 2,000 rpm and 4,500 rpm. During the pump performance, the displacement of the rotor in the axial direction is investigated.

Carbon fiber reinforced plastic (CFRP) is a lightweight, high-strength, high-rigidity, high-performance structural member. CFRP has high strength not only against static loads but also against impact loads. Therefore, the use of CFRP as an energy absorbing member is being studied. However, there are few reports on energy absorption by CFRP during crushing. To grasp the absorption characteristics for impact energy, we conducted drop weight tests with CFRP test pieces. The shape of the test pieces was decided cylindrical shape which the impact load is evenly applied to the test piece. In order to compare the crushing characteristics of CFRP by the number of layers, cylindrical test pieces with different numbers of layers were prepared. A drop weight test was performed using the test pieces and the load and crush displacement were measured using a load cell and laser displacement sensor. Also, we photographed the situation using a high-speed camera. Two-layer and four-layer specimens were examined. From the experiment, it was found that the broken carbon fibers were scattered during the crushing. This indicates that delamination occurred in the area where the weight contacts. The carbon fibers oriented in the axial direction were finely cut, but the carbon fibers oriented in the circumferential direction tended to be cut into fibrous shapes. The energy absorption was almost the same for the two test pieces with different numbers of layers. It was found from this experiment that the CFRP member is crushed by the impact, and the amount of crushing can be reduced by increasing the number of layers, and the energy can be absorbed in a short time. In the future, we will carry out a detailed investigation of test pieces with different numbers of layers.

The ultra-compact EV which has one or two seaters have been researched and developed for new eco-friendly transportation system recently. The main interior noise are road and wind noise in this vehicle which have a large impact on occupant comfort in the interior space. Because this vehicle has electric motor instead of engines. However, the countermeasure for interior noise of ultra-compact EV has not been done due to available space and increase weight of this vehicle. Therefore, regarding with active noise control for interior noise environment of ultra-compact EV, it is extremely important to provide ride comfort according to various situations and the space preference of a passenger to advance the high-value-adds of automobiles. We have been researched ride comfort of interior noise environment for ultra-compact EV by using brain wave measurement which is one of the biological information and quantitative evaluation of ride comfort by analyzed measured brain wave data. In this paper, we considered noise environment effect for driver using measured brain wave under the different noise condition during driving by driving simulator. In the experimental noise condition, we used road noise which is 70 dB at ear of driver considering driving situation and assumed noise reduction condition. From the experiment result, we proved that the brain wave measurement result was different when the participant drives under the different noise condition. In addition, from the result of the free description type questionnaire answer, drivers felt a burden during driving operation.

At the front of the vehicle, there is a front side member (FSM), which is the main skeleton of the vehicle, and a crash box (CB) attached to the tip that absorbs impact energy. In the event of a collision, it is necessary to improve the energy absorption performance and absorb more energy with less deformation without deforming the FSM. In this study, carbon fiber reinforced plastic (CFRP) was used for CB. CFRP can be easily formed into the shape required by the designer. In order to compare the crushing ability of CB, a drop weight test is performed using test pieces with partially different numbers of layers. To compare the impact energy absorption performance of the proposed CFRP pipe, two types of test pieces in which the length of the part where the ply number of prepreg of CFRP was reduced partly was different were produced for the drop weight test experiment. From the experimental results, the test piece with the long portion where the structural strength was intentionally reduced was able to decrease the impact load in the whole of the crushing process. Accordingly, it is obtained that the crushing amount of the test piece could be controlled by changing the ply number of test pieces and creating a part where the strength was intentionally reduced.

The paper proposes a vibration suppression method of elevator-rope-sway by avoiding resonance between the building sway and the elevator rope based on a negative stiffness spring mounted near a bottom end of the rope. The negative stiffness can change the natural frequency of the rope. As a result, the resonance between the building sway and the elevator rope can be avoided. This paper describes the design and analysis of the negative stiffness in a passive vibration suppression device by using a transfer function of a wave equation which is described as a partial differential equation. The validity of the proposed method is confirmed by experiments.

This research aims to find a better design of cartilage plate used in myringoplasty, a surgical procedure to reconstruct the tympanic membrane (TM) of human middle ear when it is perforated. A detailed three-dimensional finite element model of human middle ear is created and used to investigate the effects of thickness variation of cartilage plate on sound transmission. The validity of the numerical model is verified by comparing the vibration response of the stapes footplate with that of the measurement results of other researchers under a sound pressure of 90 dB. Then, a reconstructed model is created by replacing an assumed perforation on the TM with a uniform thickness cartilage plate. Varying the thickness of cartilage plate from 0.1 mm to 0.7 mm, and evaluating the displacement of stapes footplate in a frequency range from 0.1 KHz to 10 KHz, frequency response analysis show that 0.3-0.5 mm models have the best performance than others. However, from the viewpoint of quality of life (QOL), there is still a large difference between the performance of reconstructed models and that of the heathy model. As a further investigation, instead of adopting a uniform thickness, the thickness of the cartilage plate is designed into several patterns by combination of thinner layers and thicker layers. The frequency response curves of some patterned models show better matching to the curve of healthy model than using uniform thickness plate. From these results, a further improvement can be expected by optimizing the pattern design.

In this paper, the temperature compensation of an eddy-current displacement sensor using zero power control is confirmed by experiments. In zero power control, the control current is set to zero for a constant disturbance by changing the bias force obtained from the permanent magnet by controlling the position of the levitating body. We use the local current feedback control in this experiment among several methods of zero power control. By using a model of zero power control using the transfer function, it was confirmed that constant or low-frequency disturbances to the displacement sensor can be cancelled out by zero power control. The experimental apparatus is a basic magnetic bearing that supports only one axis. The eddy-current displacement sensor used for magnetic levitation is cooled from room temperature to liquid nitrogen temperature. The temperature drift of the eddy-current sensor, the displacement, and the control current were measured in the experiment. The eddy-current sensor used for position detection in magnetic bearings was cooled from room temperature to liquid nitrogen temperature while the levitating body was levitated. The temperature drift of the eddy-current sensor output was confirmed from the experimental results. Since the change in sensor output with temperature was very slow, the rotor was confirmed to levitate without any problems near the balanced position.

In this study, we investigated the effect of the driver's intention on steering behavior. This study aimed to evaluate the difference between the driver’s behavior during automatic steering, regardless of the driver’s intention, and normal driving, considering the driver’s intention. In the case of the driver’s intentional steering, the driver’s center of gravity (COG) moved in the opposite direction to the centrifugal force before turning, which stabilized the driver’s posture. During automatic steering, the driver’s COG did not move in advance. Furthermore, it was demonstrated that a scenario occurred when the driver’s COG moved significantly during automatic steering.

In recent years, due to environmental problems and aging society, demand for ultra-compact vehicle is increasing. An advantage of ultra-compact vehicle is that they can be used on narrow or rough roads. However, such roads have many steps and irregularities on the ground, and it is expected that ride quality will deteriorate. The authors have proposed mounting a small active seat suspension on the seat as a way to improve ride comfort. The method of evaluation for the psychological state is required to improve ride comfort. In this study, we investigated quantitative and objective method for evaluation of ride comfort. First, ride comfort of participants was evaluated using visual analog scale of subjective evaluation and biological information in exposing experiments. In exposing experiments, an experimental participant was oscillated by 5 Hz sine wave for 3 minutes. Biological information which is heart rate variability was used evaluate the experiments. Second, we selected the biological information for estimating the riding comfort from the correlation between the biological information and the psychological state. Finally, multiple regression analysis was performed using biological information to establish a prediction formula.

Currently, thin steel plates are widely used in industrial products, including the automobile industry. In the factory, the continuous thin steel plates are subjected to iron, and steel processes is supported by a series of rollers during processes such as plating and rolling. However, because the rollers contact with the steel plates, the problem of surface quality deterioration arises. To solve this problem, we developed a non-contact guide system for parts of the steel plate at which its traveling direction changes in high-speed traveling by applying an electromagnetic force from the direction of the edge of the thin steel plate, and experimentally examined the effectiveness of the system. In addition, structural analysis was performed by the finite element method, and a permanent magnet was placed in the antinode of the eigenmode. It was experimentally confirmed that vibration can be suppressed by disposing of permanent magnets. In this study, we examined experimentally the tendency of vibration suppression and control performance by changing the feedback gain. From the experimental results, the vibration can be reduced in the active direction by increasing the velocity gain, which is a control parameter. However, vibration increased in the non-controlled direction. From this result, it was found that the control direction and the non-controlled direction showed opposite tendencies.

In a thin steel plate production line that is widely used for industrial products, contact conveyance by rollers is performed. The deterioration of the quality of thin steel plates is a problem because scratches and irregularities occur on the surface of thin steel plates. Therefore, non-contact magnetic levitation transfer of thin steel plate using the attractive force of electromagnets has been proposed．In the past, we proposed a system in which an electromagnet was installed at the edge of a steel plate and the conventional magnetic levitation device for thin steel plates was installed with the electromagnet installed vertically. We have been studying a system that conveys magnetically levitated horizontally. We have also studied a curved magnetic levitation system using the flexibility of thin steel plates. However, the disturbance input to the thin steel plate at this time is only in the vertical direction．Furthermore, we have not examined the levitation performance of a new magnetic levitation system that uses a horizontal positioning control system and a curved magnetic levitation system. In this study, a thin steel plate was curved and levitated. The effect of the magnetic field tension from the horizontal direction on the thin steel plate was examined experimentally. As a result of the experiment, it was confirmed that increasing the tension due to the magnetic field from the horizontal direction does not always improve the floating stability.

In recent years, ultra-compact electric vehicles (EVs) have become popular and been used as transportation tools for traveling within a community area. However, it is difficult to satisfactory install an assist mechanism for steering operation, power steering systems, and other driver assistance systems because of owning their compactness. To solve this problem, our research group has proposed to install a steer-by-wire system (SBWS) with an electronic rather than mechanical connection between the steering wheel and the tires. We aim to find the optimal reaction force at the steering wheel that can reduce the burden on the driver. Therefore, an upper limb analysis model using the driver's biological information was created and simulated. In this report, we simulated the burden of the driver's arm when the steering angle was changed while the seat slide adjustment and steering reaction force was constant. The effect of the steering reaction force on the steering burden was also investigated by simulating three patterns of steering reaction force. As the results of the simulation, it was found that the steering burden of the driver's arm tends to increase as the steering reaction force increases. In addition, it was confirmed that the effect of the steering burden due to the difference in the reaction force decreases as the steering angle increases.

The system to assist the driver of a car has been developed by progress of control technology. Since the vehicle weight increases due to the installation of the assist device, it is necessary to improve the power of the engine to exhibit the same acceleration performance as before. Therefore, focused on an electromagnetic drive valve system (EDVS) that drives a valve train using a linear motor as a new VVT. This has been established as a method for fundamentally solving the abnormal motion that occurs in systems when using conventional valve springs. We propose a system that uses this EDVS to improve the output by freely changing the valve lift and opening/closing timing for each engine speed. In this study, EDVS is using a linear motor with PM as a stator and a coil as a mover. We conducted electromagnetic field analysis by the finite element method and investigated changes in thrust characteristics when the magnetizing direction of the permanent magnet (PM) of the actuator was changed. In this analysis, the direction of the current flowing in the coil was fixed in order to study the effect of the magnetization direction of PM on the thrust. As a result of the analysis, it was confirmed that the vertical magnetization model tends to have higher thrust when the upper and lower magnets are magnetized in opposite directions. This is because in the vertical magnetization model, by turning the upper and lower magnets in opposite directions, the lower magnet generated a magnetic force that repelled the coil, and the upper magnet generated a magnetic force that attracted the coil. The thrust of the actuator could be improved by changing the magnetization direction of the permanent magnet.

Tactile sensing recently becomes more important in the robotics field and many tactile sensors have been researched and developed, however, miniature and low-cost sensors have not been widely used in practical applications. For miniaturization and cost reduction, we have proposed and developed tactile sensor using microcantilevers fabricated by technologies of micro-electro-mechanical systems on the surface of a silicon chip and embedded in the elastomer with the hemispherical bump. In this study, to optimization of sensitivity of the tactile sensor, we have analyzed behavior of multiple microcantilevers in the elastomer. Deflection behavior of microcantilever models with application of force to the elastomer was calculated by the finite element analysis. From the analysis result, deflection amount and surface compressive strain of microcantilevers increases with applying force to the bump of elastomer. Furthermore, increase of deflection and compressive strain for microcantilevers arranged in external side is larger than that in internal side. On the other hand, the sensitivity of resistance of strain gauge on the microcantilever to force was measured experimentally. The sensitivity for the microcantilever arranged in external side on the chip surface is larger than that in internal side and indicates similar tendency to compressive strain. Therefore, by analyzing compressive strain corresponding to sensitivity using the finite element method, we can optimize the sensitivity of the tactile sensor.

This paper proposes a design method for the active mass damper (AMD) applied to super high-rise buildings designed as a building mass damper (BMD) The BMD is a seismic response control device with a soft layer at a relatively high position in the building, and makes the part above the soft layer work as a tuned mass damper. It is designed to decrease the seismic response of the part below the soft layer by a motion of the superstructure. However, since the displacement of the soft layer is limited, any displacement exceeding the allowable clearance must be suppressed. The displacement of the soft layer can be reduced with additional damping and/or springs. However, the addition of damping and/or springs has the countereffect of increasing the seismic response of the building. To solve this problem, we proposed the design method for the AMD, which aims to make the BMD with additional damper and/or springs act like a BMD with no additional element. The effectiveness of the proposed method was demonstrated through numerical calculations.

Some examples of subsynchronous vibration occurred in the starved condition bearing are reported, for example, in the API 684 Standard Paragraph it is introduced that the subsynchronous vibration experienced in the high-speed balancing test facility in the vacuum condition and the cause is confirmed to be the starvation of bearing. Because in the vacuum condition of the test facility the pressure inside the bearing housing was low and estimated to be starved. In this example after installing the proper end seals in the bearing housing can increase the pressure inside of the bearing housing and avoid the subsynchronous vibration.

As the authors experienced the similar operation in the actual machine in the same situation in the high-speed balancing facility. The rotor type is a back- pressure steam turbine for the turbo generator unit. The bearing types is 5 pad tilting pad bearing. The effects of starved oil film on the subsynchronous vibration was doubted. But generally, the fluid film analysis in the starved bearing cannot be performed because the fluid film will not be established correctly. Therefore, the analysis in this paper is tried applying smaller size bearing pads to simulate the estimated remaining oil film sizes with carrying same bearing load. The size of bearing pads is changed parametrically depending on the estimated starved oil film.

In the current stage it will be difficult to know the starved oil film size or remaining oil film size correctly. But the effects of the estimated starved film condition on the stability in rotor can be evaluated by applying dynamic analysis to the rotor-bearing system. From the results the excessive small damping ratios in the system could be obtained and the estimated starved bearing film condition was simulated.

This paper aim to improve an efficiency and a performance of a control system design by integrating a tilt control and a vibration control for a car-body tilting vehicle using air springs that have been conventionally treated separately. In this study, as a basic study, equations of motion for a 6 degrees of freedom railway vehicle model including air springs were formulated. Then simultaneous control of the tilt and the vibration was performed by linear quadratic integral control to the model. The effect of the vibration control was confirmed. Frequency response of simulation results of a vibration control of a vertical motion. The peak gain decreased by 14[dB]. And, frequency response of simulation results of a vibration control of a roll motion. The peak gain decreased by 19[dB]. A followability to the target value is confirmed when the target tilt angle is input as a step. The tilt angle of the car-body reaches the target tilt angle in about 2 [sec]. In addition, the car-body tilt angle converges to the target tilt angle without vibrating. As results of a control simulation, the effectiveness of simultaneous control of the tilt and vibration of the car-body tilting vehicle using air springs was confirmed.

This paper aims at the realization of a large robot arm over 20m height. In the previous research, advantage of multistage robot to ease stress is confirmed and its control algorithm is discussed. However, its mechanical property has not been investigated precisely. In this paper, a method to prevent the wire supporting the self-weight of the arm from breaking is examined. The method is to wind a spring around the wire. It was found that this method allows the designer to set the maximum tension that acts on the wire.

In this study, we focus on a stand-up type personal mobility vehicle (PMV) with three or four wheels that ensures static stability. A PMV is typically compact and lightweight, and the dynamic behavior of the driver affects the dynamics of the entire system. Thus, it is important to investigate the dynamic motion of the driver. Additionally, the difference between the driver’s intentional and unintentional motions should be considered for applying automatic driving or driving assist to a PMV. Therefore, we measured the basic motions of a standing human during braking. Two types of experiments were performed: one using a treadmill to accelerate the static vehicle backward to simulate braking; the other using an actual PMV, with the driver intentionally or unintentionally braking, assuming automatic driving. The experiments demonstrated that by holding the handle when the posture changed owing to braking, the pressure was dispersed from the feet to the side of the handle, and this pressure was equivalent to approximately 30% of the human body weight. In the experiment using a PMV, we observed a significant difference in the drivers’ maximum center of gravity position (COGP) during braking between the with- and without-handle cases, indicating that the center of gravity (COG) movement was significantly suppressed by the handle. However, there was no significant difference in the maximum COGP between the intentional and unintentional braking cases. It was assumed that the driver roughly predicted the braking position owing to the limited experimental space. Furthermore, based on our simulation, it was assumed that the drivers’ upper and lower arm positions had a low impact on the displacement of the drivers’ COGP during braking. These findings can be applied to the modeling of human-PMV systems, and are expected to be useful for designing the forms and dynamic control systems of PMVs.

A “smart gear monitoring system” has been developed that consists of an observation antenna and a crack detection sensor with another antenna printed on gears. When the characteristics of the observation antenna were measured with the magnetic coupling between the two antennas printed on POM plates, it was found that the return loss changed significantly depending on whether the crack detection sensor was damaged or not. The obtained results, however, have not been examined in detail. In this paper, the effect of the characteristics of gear sensors on the return loss of the observation antenna is discussed through the experimental results. First, two spiral antennas with the same geometrical shape were printed on POM plates. One was connected to a network analyzer and the other was connected to a variable resistor or variable capacitor. Then, the return loss of the observation antenna was measured while the magnetic coupling was caused by bringing the antenna pairs close to each other. Furthermore, the effect the return loss of the observation antenna was investigated and evaluated by changing the value of the resistance and capacitance. Consequently, the results have shown that the resonance frequency of the coupled system was affected in corresponding with the variation of the capacitance and the Q value was apparently affected in corresponding with the variation of the resistance, respectively.

In order to investigate the feasibility of high-altitude flight of a kite, the static force balance on a mooring cable and a kite is considered. The kite is treated as a single-point mass and the mooring cable is divided to multiple fragments with mass. First, the kite-flying experiment is carried out to validate the analytical technique. The kite flies at a height of 94m and the measured tensile force is about 12N. Next, the flight at height of 5km is investigated analytically. Normally available polyethylene line can withstand the required load and the flight is shown possible. Moreover, it is shown that the 7km flight is also possible by using ultra-high-strength polyethylene fiber. For a higher-height flight it is not possible in the analyses made here.

The energy harvesting from mechanical vibration and impact is focused on as a self-sustainable power source for the purpose of gathering a driving energy of wireless sensors. Even if a recent low energy consumption system, a frequent access for the sensor or a continuous measurement requires a certain amount of energy for the wireless sensor node. In this study, a high efficiency energy harvester gathering from mechanical vibration and impact by means of electromagnetic induction is proposed. It is composed of both two ring-shape magnets with the same magnetic poles facing each other and a high saturation magnetization FeCo core. A 30 mm diameter and 20 mm height harvester fixed on a plate-spring achieves a 3 V – 1.2 mW generation extracted from 0.15 G – 49.5 Hz ambient vibration.

Thin steel plates are widely used as materials for automobiles, electric appliances, cans, and other products in current industries. Recently, the manufacturing of extremely thin steel plates has become possible, and with various industrial demands, the surface quality of steel plates continues to be enhanced. Research on non-contact transport technology is being carried out in order to apply magnetic levitation technology using electromagnets to the transport systems used in production lines for thin steel plates. When an ultrathin and flexible steel plate is to be levitated, levitation control becomes difficult due to the flexure of such a plate. Therefore, we previously proposed a bending levitation system in which an ultrathin steel plate is bent to an extent that does not induce plastic deformation. However, in an actual usage environment, there are electrical noise and mechanical disturbances, which deteriorate the levitation performance. Flexure of the ultra-thin steel plate in magnetic levitation can be obtained by numerical analysis. In this paper, in order to investigate the levitation stability of ultrathin steel plate, the bending magnetic levitation was simulated by numerical analysis. We use finite difference method for the simulation of curved magnetic levitation by numerical analysis. As a result, the bending magnetic levitation could be reproduced by the numerical analysis using the finite difference method.

We propose to combine the backstepping method with the reinforcement learning to take advantage of each method, where learning is not performed at once, but is performed step by step following the structure of the plant to be controlled. To demonstrate the basic idea, a tracking control problem of a wheeled mobile robot (WMR) under a nonholonomic constrain is discussed. Firstly, a tracking controller at the kinematic level is obtained by reinforcement learning with the actor critic structure, and then the actual control law is obtained by applying the reinforcement learning again taking the actuator dynamics into account by using the (fictitious) kinematic control obtained at the first step

In this research, it is aimed for a driver assist system at the time of the tire burst considering a driver behavior. The system is aimed for a realization of the driving support until it stops safely while performing the steering support of the vehicle. For this purpose, this paper deals with an influence of delay time on a driving assistance system for a tire burst. Driver’s tests using CarSim DS under the tire burst situation were performed for an investigation of an influence of delay time on a driving assistance system. In a driving test, a control input is a steering torque. For the control input, the value of the steering torque to keep the lane under the tire burst situation was experimentally determined. By the steering torque, effects of a delay of the steering torque input timing was evaluated. The timing of the input of the steering torque is ‘no delay’, ‘0.3 seconds delay’ and ‘0.5 seconds delay’. The subjects of the driving simulator test were 10 people in their 20s who had a car license. The subjects were instructed to drive at a constant speed of 100 km/h so as not to depart from the lane only by steering without operating the accelerator pedal and brake pedal. The evaluation of the experimental results was performed by the amplitude of the lateral displacement in the time history responses and the questionnaire to the subjects. From the experimental results, the control delay makes the operation feel difficult, and it is necessary to keep the control delay time within 0.3 seconds.

An active seat suspension was proposed to improve ride comfort of the ultra-compact vehicle. Discomfort vibration for vehicle occupants was reduced by active control of the seat suspension. In previous studies, a control system of the seat suspension that feeds back the displacement and velocity of the seat surface was used. This system measures the acceleration in the vertical direction from an accelerometer mounted on the seat surface. The displacement and velocity from the equilibrium point were calculated by digital integration against acceleration. However, the error generated by digital integration may affect control performance. The ideal method for vibration control is feedback control using acceleration directly. In this study, a control system that directly feed back the absolute acceleration measured on the seat was proposed. To investigate the performance of vibration control, vibration response of this control system was measured using the experimental apparatus assumed the active seat suspension. In this experiment, vibration response of the model was investigated by input disturbance from a vibrator. Moreover, setting feedback gain is important factor for improving control performance. We investigated the change of the vibration suppression effect by the feedback gain to improve control performance. From experimental results, the ride comfort which applied acceleration feedback control could be improved by selecting proper feedback gain because characteristics of frequency was changed by the feedback gain.

In this study, we investigate the modeling and vibration suppression control of single-mast stacker cranes for an automatic warehouse. Conventionally, in the design of a stacker crane, a two-stage analysis is often used in which a mechanism analysis is first performed assuming that all bodies are rigid bodies, and the obtained maximum load data is exported to a structural analysis. In addition, studies on vibration control often do not sufficiently consider the coupling between motion and vibration. In this study, the equations of motion of the mast, which is a flexible body, is expressed using the floating frame of reference formulation. In the formulation, the coupling between motion and vibration is strictly considered. However, in the floating frame of reference formulation, it is difficult to formulate sliding joints which causes a problem of a moving boundary condition. Therefore, we formulate the sliding joint constraint in which the carriage travels on the mast as an algebraic constraint including the dummy variable. Based on the derived flexible multibody dynamics model, we propose a residual vibration suppression method that actively utilizes the dynamic coupling between motion and vibration. Here, the reference trajectory of the cart and the carriage is represented by a B-spline curve, and a simple and practical algorithm for sequentially improving the trajectory by correcting the control points is formulated. It is confirmed that a large vibration suppression effect can be obtained by the proposed method through numerical simulation.

In this study, we devised an active device which is used to suppress the essential tremor in human limb. The tremor can be observed in most human arms under excessive stress or chills, even he/she is at physically well condition. Therefore, the tremor may cause anyone a bad effect on precise operation, e.g. welding and surgery. In this work, experiments are performed where the simulated microscopic surgery is imposed on subjects whose fingers are equipped with the active mass damper attenuating the tremor in their hands. The damper is actively driven according to the state feedback controller designed according to the linear two-degrees-of-freedom vibration system model. Subjects were asked to grip a needle having a relatively small diameter using tweezers, and were also asked to insert it in a needle with a larger diameter. Tremors were measured while the subjects kept the tip of the needle in place. The damper was shown to be effective for attenuating vibration in human fingers.

This paper discusses the development of an automatic lettuce harvester. Automatic harvesting of lettuce is extremely difficult and no commercial harvester has yet been developed. Because the stem of the lettuce to be harvested cannot be determined visually, it is difficult to estimate the cutting position of the stem. Furthermore, the film that covers the ridge on which the lettuces grow must not be damaged. Latex oozes out from the cut end of the stem and must be stopped in a few seconds to avoid browning the cut end of the stem. We developed an automatic harvester that can overcome such difficulties. Herein, an outline of the mechanical design as well as the control method of the harvester is introduced, for example, the automatic harvesting technique that does not damage the film covering the soil in the field, estimation technique for the appropriate cut position of stem that leaves a specified number of outer leaves, and stopping technique of latex from the cut end of the stem within a few seconds. We developed an automatic harvester that utilizes such novel techniques. The effectiveness of the developed harvester was verified by experiments in the field and the results are presented.

This paper proposes a new active steering system for motorcycles, which may be thought of as a steer-by-wire system, together with controller design methods. One of the features of the system is to use only one motor taking system failure into account, while two motors are used in most steer-by-wire systems to provide the driver (rider) with shaped reaction torque. The proposed system can also provide reaction torque which cannot be shaped arbitrarily unlike the existing systems. In this way, the reduction of control freedom makes it more difficult to improve the maneuverability and safety simultaneously. With this mechanism, therefore, two operation modes; 1) normal driving, 2) emergency assist are considered, and sliding mode control and LQR theories are applied.

This paper presents an analytical and experimental study on the transient behavior of the response stabilization control for a nonlinear wideband vibration energy harvester in order to clarify the energy requirement to stabilize the high-energy orbit of the nonlinear oscillator in the harvester subject to sporadic disturbance. In the nonlinear vibration energy harvesters, a well-recognized difficulty of coexisting attractors then arises that the emergence of the response in the high-energy branch is not guaranteed because it depends on the initial conditions to which steady-state solutions the state is attracted. To solve this problem, the response stabilization control by a negative resistance, which injected a part of the energy back to the mechanical oscillator to destabilize the undesirable low-energy solution and make the high-energy solution globally stable. However, the power necessary to operate the resonance stabilization control was supplied by an external power source, so that the power consumption by the control circuit is still a critical problem. In this study, the energy consumed by the NIC was evaluated by examining the transient response of the harvester induced by the disturbance, which was modeled as a phase discontinuity in the sinusoidal excitation. The experimentally observed responses were characterized as the trajectories on the phase plane, and the flow fields derived by averaging method successfully explained the measured trajectory, which affirms that the transient response of the harvester can be described by the slow dynamics derived by the averaging method. It is also suggested the further investigation for the quantitative evaluation of the power consumption based on the slow dynamics.

In recent years, there has been considerable interest in developing piezoelectric cantilevers for energy harvesting. Most cantilever-based harvesters are difficult to adapt to the multi-directionally complex vibration environments because of its unidirectional, which results in the dissipation of the multi-directional energy source and cannot be effectively harvested. This article proposes a cantilever-asymmetric-pendulum combined structure that is formed by a flexible cantilever beam and an asymmetrically conical pendulum with a rigid thin rod and two different concentrated end masses. With the nonlinear coupling between the motion of asymmetric pendulum in 3-dimentional space and the vibration of beam bending, 1:2 internal resonance is induced to enable that the multi-directionally vibration can be delivered to unidirectional cantilever bending, for effectively harvesting vibratory energy of excitations from an arbitrary direction. Lagrange’s equations are utilized to establish mathematical models of the combined structure, and numerical simulation is carried out to analyze the characteristics of systems responses under x-direction excitations and z-direction excitations. Simulation results verify that, with internal resonances, the cantilever-asymmetric-pendulum system responses optimally under excitations around both the asymmetric pendulum natural frequency and the complete system natural frequency.