Various methods to estimate a vehicle trajectory and attitude using the Global Positioning Systems (GPS) and Inertial Measurement Unit (IMU) are proposed ordinary. The features of this research are the real-time GPS-IMU fusion based on the discrete-time Kalman filter described by a simplified linear state equation. A method to simplify the state equation is based on the precise vehicle position data measured by GPS and the acceleration error caused by vehicle attitude error estimated by Kalam filter. The additional method to simplify the state equation is to remove the coordinate transformation from the state equation. The vehicle trajectory is estimated correctly by the specific force cancelled the acceleration error from the measured data and the vehicle attitude is estimated correctly by the orthogonal geometry between specific force and acceleration error. This paper describes the vehicle trajectory and attitude estimation method by the above acceleration error separation and the practical evaluation results about this trajectory and attitude estimator simultaneously.

View full abstract

A pressure wave propagating in a tube often changes to a shock wave because of the nonlinear effect of the fluid it is traveling through. The purpose of this study is to establish a practical analytical model to analyze this phenomenon. In the first report, a concentrated mass model was proposed to analyze a nonlinear pressure wave phenomenon in a straight cylindrical tube. In this paper, the modeling of a branched junction is proposed. The model at the branched junction consists of masses, nonlinear pressure elements, base support dampers, and nonlinear dampers. The nonlinear damper is derived from pressure loss at the branched junction. To confirm the validity of the proposed branch model, the numerical result obtained by the concentrated mass model is compared with the theoretical value of the transmission loss of a branch pipe. Additionally, an experiment on a sound tube with a branch pipe is performed and the experimental result is compared with the numerical result. All numerical computational results agree very well with the theoretical value and the experimental results. Therefore, it is concluded that the proposed branch model is valid for the numerical analysis of nonlinear pressure wave problem in a tube with a branch pipe.

View full abstract

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 defined to be self-excited vibration caused by leakage flow induced vibration here. In this study, as the first step, the theoretical model of non tapered clearance flow passage is assumed and the natural frequency is obtained. On that basis, experiments are performed and the validity of the theory is examined. As the second step, in case of tapered clearance flow passage, the concentrated load is added to the belt, and the effects of the belt deformation, the flow rate and the added loads on the clearance flow are examined. The generation mechanism of the abnormal vibration is considered. As a result, it was clarified that the presented theory was useful in case of non tapered clearance and the generation mechanism of the self-excited vibration was due to the phase shift by the change of the parameters.

View full abstract

Rotating machinery is widely used in the industrial plant, for example, power plant, chemical plant, mass-production plant and so on. In order to ensure safety operation of the rotating machinery, vibration condition monitoring of the machinery can play a crucial role. In this study, the vibration power generator of the piezoelectric bimorph cantilever beam was proposed for vibration condition monitoring applications of rotating machinery. Proposed piezoelectric vibration power generator consisted of Macro-Fiber Composite(MFC) actuator which is flexible and durable piezocomposite type actuator. The mechanical resonant frequency of the cantilever beam was tuned to the rotating speed of a typical 4-pole induction motor driven rotating machine. This study evaluates the power generation performance of the proposed power generator through mumerical simulations as well as experiment when subjected to vibration source input magnitude of 0.71mm/s(RMS value of velocity) at the resonant frequency of the cantilever beam by using the electrodynamic shaker. The experimental results of the vibration power generator were good agreement with the numerical simulation results using 2-dof model of the vibration power generator.

View full abstract

In structural designs considering thermal loading, maximization of temperature diffusivity as well as structural stiffness are important and indispensable goals that optimal solutions to design problems need to achieve to reduce operating temperatures and extend product durability. In this paper, a new topology optimization method, based on the level set method and Finite Element Method and including design-dependent effects, is constructed for coupled thermal and structural problems, and multi-objective optimization problems having generic heat transfer boundaries in a fixed design domain are formulated. First, a topology optimization method for coupled thermal and structural problems that uses a level set method incorporating fictitious interface energy is briefly explained. Next, a new objective function that can take into account both temperature diffusivity and stiffness maximization is formulated, based on the concept of total potential energy maximization for the thermal and structural problems. An optimization algorithm that uses the Finite Element Method when solving the equilibrium equation and updating the level set function is then constructed. Finally, several numerical examples are presented to confirm the usefulness of the proposed method.

View full abstract

This paper examines the resonance characteristics of the wave power generation device, which consists of pulley (s), wire (s), floats (s), counterweight (s) and ratchet mechanism. The resonance analysis model introduces the relative displacement between the water level and the float's position into the dynamics model for the system in operation. The equations of the natural frequency, the ratio of the frequency of water wave to that of the natural frequency, the damping ratio and magnification ratio have also been given. Moreover, the behaviors of the average occurred electric power and maximum wire tension have been examined for wave periods around the natural period of the system. The relationship between the natural period of the system and the float dimensions, especially the float's diameter/height ratio, has been examined. As an example, the annual average occurred electric power and energy conversion efficiency have been evaluated for the system with natural period near dominant wave period when it operates off Kobe port where the annual wave period varies in a relatively narrow range.

View full abstract

In this paper, we design a quaternion-based attitude controller for small electric helicopter. Firstly, we derive a MIMO(Multi-Input Multi-Output) nonlinear attitude model of a small helicopter. In this model, we adopt the quaternion for attitude expression. This model consist of three parts, the dynamics of quaternion, the Euler's equation, and the dynamics of main rotor and stabilizer. Secondly, we design a MIMO controller by using backstepping control method which is one of nonlinear control method. The asymptotic stability of the origin of error system is achieved by this controller. Simulation and experiment results show that the nonlinear controller is more effective than linear controller which was used in previous study.

View full abstract

The accuracy of small and low cost GPS is insufficient for precise landing of MAV. This study aims to land on an MAV size landing target by using outer sensors. This paper describes about proposed movable outer sensor system for measuring outer environment and an algorithm of position measurement. A movable outer sensor system consists of four IR rangefinders, four servo motors and one ultrasonic rangefinder. In order to measure the MAV position, sensor system vertically swings each IR rangefinders using servo motors and detects edge of landing target. And this sensor system calculates the position from measured edge direction and ultrasonic altitude. Additionally, an experiment of autonomous hovering over the 52cm×52cm table and autonomous landing was carried out in indoor environment by using proposed sensor system. As a result of the experiment, it has been successful that our MAV could fly keeping horizontal position within 17.9cm radius circle, and landed on the table from 50cm height.

View full abstract

The effects of surface tension on picking up a minute object by a water drop were studied experimentally. The self-centering effects of the proposed method of picking up a microchip was demonstrated in the 1st report. In this method, the stability of forming a drop and sufficient capillary force for lifting up the chip are important. This paper investigated the effect of liquid surface tension on them by using isopropanol (IPA) and its water mixture. The surface tension of water is about three times that of IPA. It was found that the maximum wetting angle on the top of nozzle increased as the ratio of IPA to water decreased. As a result, larger drops were enable to be formed as the ratio of IPA decreased. The adsorption force of a drop was measured for IPA-water mixtures. It was found that the adsorption force of a drop was sufficient to lift up a microchip.

View full abstract

The paper proposes multiple magnetic suspension systems. The concepts are presented by using their basic models. They are classified according to multiple structure, power amplifier and coil connection. According to the first item, they can be divided into series and parallel. This paper mainly treats the latter. The controllability and the observability of each parallel suspension system are discussed based on its mathematical model. The concept of sensorless magnetic suspension is stretched to the multiple systems. The feasibility of parallel magnetic suspension is demonstrated by simulation.

View full abstract

There is a trade-off between ride comfort and driving stability in passive suspensions for vehicles. Many studies have been done on improving ride comfort and driving stability. Semi-active uspension systems with variable dampers and variable stiffness stabilizers have attracted much attention recently due to their low cost, low energy use, and safety. Several systems have been put into practical use so far. However there is a possibility that these devices interfere in each other, because these devices are separately controlled. Therefore, it is desirable that variable dampers and variable stiffness stabilizers are controlled by an integrated control design method for suspension system. This study aims at establishing the integrated control design method for the semi-active suspension system which consists of variable dampers and variable stiffness stabilizers in order to improve ride comfort and driving stability. The computer simulations weree carried out to verify the availability of the proposed control.

View full abstract

Some experimental and theoretical investigations were carried out to stabilize the dynamic motions of a vehicle with independently rotating wheels by control of steering on wheels. Scale model (about 1/8) of independently rotating 4 wheels bogie with drive motors was made. The wheels steering angle was controlled by actuator using a personal computer with the information of lateral displacement of the bogie. Equations of motion were derived and simulation was performed. In the experiment, the differential term was added to the target steering angle calculation, and the reduction effect of an overshoot value was examined. And the change in the curving characteristics by the difference of the control rules was described. Simulations results were shown with the considerations of influence of control parameters and the qualitative agreement with the experimental results.

View full abstract

We proposed a novel car transportation system termed as iCART (intelligent Cooperative Autonomous Robot Transporters). This system transports cars using two mobile robots that move in coordination. In this paper, a leader-follower type decentralized motion control algorithm considering the effect of rolling friction at the contact of the end-effector with the ground is proposed. The consideration of the rolling friction effect is needed, because an end-effector of the robot is grounded for supporting weight of a car. The proposed algorithm was applied to the experimental system, and experiments were done. Experimental results illustrate the validity of the proposed algorithms.

View full abstract

This paper presents an assist control method for flexible part conveyance and positioning using a master slave manipulator. The proposed assist control consists of the notch filters in the master side and the shear force feedback in the slave side. The operating force signal is attenuated at the resonance frequency of the flexible part by using the notch filters, by which the excitation of the vibration of the flexible part is reduced. The vibrations of the flexible part are suppressed by using the shear force feedback. The effectiveness of the proposed method is verified from standpoints of maneuverability and operating feel. The former is based on the evaluation of the task achievement time, and the latter is based on evaluation of operating feel of the operators using subjective evaluation.

View full abstract

This paper presents the simultaneous estimation of the position and mechanical impedance of unknown surfaces using a robotic finger. Successfully treating such a simultaneous sensing device will contribute to reducing the inspection time required for industrial products, and could also be useful for detecting unknown surfaces such as in disaster zones. A novel end-effector is proposed, that is equipped with a force sensor and a resonant mechanical element, located at the last of the robotic finger. The finger itself is automatically manipulated by the velocity-based force control, and the end-effector is passively oscillated by a vibration motor. The surface estimation is attained by processing signals of the reaction force and the position from unknown surfaces to the fingertip. First we introduce the idea of the surface estimation using a robotic finger. Next the possibilities for estimating with the tracing control of unknown surfaces are studied using a computer simulation of the finger's dynamical model. Finally, the usefulness of estimating with the tracing control is verified by experiments using a three D.O.F. robotic finger.

View full abstract

We have been studying on quadruped gait using our quadruped robot "Rush", which has rotational passive joints. Among quadruped gait, "bound gait" is simple and easy to emerge for quadruped robot. Thus, most of researches on quadruped robot running have dealt with bound gait. But, bound gait of most quadruped robot differed from four legged mammals. This paper shows that the bound gait similar to four legged manmals can realized by controlling the position of the center of gravity of the robot body in both simulations and actual experiments.

View full abstract

This paper proposes an MRI compatible robotic gripper using piezoelectric actuators with strain amplification mechanisms. The structure of the gripper is designed based on reverse action tweezers. This gripper utilizes the piezoelectric effect for sensing the force and the displacement. The physical properties of the gripper are calculated from elasticity of both actuator and gripper. The dimensions of the gripper are determined by taking the elastic properties of both the actuators and gripping mechanism into account. The performance of the assembled gripper was confirmed by CAE simulation and experiments. The sensing accuracy of the gripping force and the displacement of the tip of the developed gripper were evaluated through the experiments.

View full abstract

Rehabilitation for upper limbs is important for elderly people, people who have suffered a stroke and so on. In recent years, the needs for rehabilitation support systems are increasing, which use force display system. Especially, the application of a passive-type force display system is desirable for its high safety. However, there are some directions and link positions for which it is difficult to display the force in a passive-type force display system using only passive elements. To solve this problem, a method for improvement of controllability using redundant brakes had been suggested. This method made it possible to display various force directions and various postures of virtual objects. In this paper, we research about force display ability of passive-type system with redundant brakes.

View full abstract

In this paper, we propose a small and simple slider-crank mechanism using flexible links that can flap wings over a wide angle, i.e., over 150deg, toward the development of a small flying robot modeled on insects. We then demonstrate the validity of this mechanism by analyzing the motion of the constructed butterfly-style flapping robot. Although many researchers have developed hardware inspired by flies and dragonflies, butterfly-style flight is more attractive because of its low flapping frequency and the fewer degrees of freedom (DOFs). Since a butterfly, however, has a wide flapping range of almost 150deg and claps both its left and right wings during flapping, in a conventional slider-crank mechanism, the driver and follower are parallel at the top dead point and insufficient torque can be generated for flapping. To overcome this problem, we have developed a slider-crank mechanism using the stored elastic energy of flexible links that can generate sufficient torque even at the top dead point. The constructed butterfly-style flapping robot with this mechanism realized a wide flapping range and, furthermore, the characteristics of butterfly-style flight, i.e., upward flight during the down stroke and forward flight during the upstroke.

View full abstract

This paper proposes a designing method for a driver's erroneous operation free transmission gear shifting system. In a parking lot, the driver has some possibility to press an accelerator pedal to go forward quickly nevertheless the gear shift into the reverse. The car rushes into backward and hits something. This accident comes from driver's misunderstanding of the vehicle's operational situation. By observing driver's accelerator pedal operating behavior and predicting driver's intention whether the driver wants to go forward or backward using Mahalanobis generalized distance in the discriminant function, the proposed system can detect the driver's wrong operation and stop engine system to avoid collision. Important notices to be paid an attention to design the real system are discussed.

View full abstract

A theoretical analysis for the shear horizontal (SH) wave in a thin plate with the material nonlinearity has been conducted by using a microscopic scalar model. In the present study, the effects of the material nonlinearity and dispersion of the wave are taken into account. Especially, the influence of the material nonlinearity of second order is also considered in addition to that of third order. A governing equation which describes the behaviors of the SH wave is derived from the microscopic scalar model. Since the governing equation is complicated, some mathematical techniques are applied in order to analyze the behaviors of the SH wave. As a result, it is shown that the SH wave which can propagate through the thin plate without dissipation exists theoretically. The factors which have the effects on the propagation of the SH wave are revealed clearly. Moreover, the conditions which make the SH wave exist without dissipation are shown analytically.

View full abstract

Recent development of high-directional loudspeaker based on parametric array has allowed sound transmission within a narrow range of acoustic space like 'spotlight'. Parametric array utilizes the high directive characteristics of ultrasonic sound, where the embedded difference component of two ultrasonic carrier waves is expanded as audible sound. This peculiar characteristic can be implemented as one measure for improving active noise control scheme controlling acoustic field locally without adversely influencing vicinal space. In the present study, a new approach for active control of sound in free space is developed using high directional parametric loudspeaker as a control source. A numerical model of parametric array source is studied, and the calculated sound fields are compared with the measured fields formed by a commercial parametric loudspeaker. Furthermore, an approach for the active control of sound in free space is investigated, and the results are evaluated mainly from the aspect of the interfered sound field. It is known that the suggested ANC system can mitigate sound locally but cause less influence on sound field in circumferential space.

View full abstract

This paper addresses the active noise control of sound transmission loss of polymer film. It is well known that the sound transmission loss is dependent on mass of material. Then, because of its lightness in weight, polymer film is unsuitable for noise insulating material. Applying active cluster control method consisting of both cluster filtering and cluster actuation, we propose lightweight acoustic isolation system utilizing a polymer film. First, we investigate the correlation between the mechanical properties of materials and acoustic radiation characteristics. Next, an optimal feedforward control law for minimizing acoustic radiation power is derived. Under the optimal control, sound transmission loss of a simply supported polymer film embedded in an infinite baffle is calculated. Finally, the correlation between the mechanical properties of materials and the control effect applying active cluster control method is discussed.

View full abstract

FDI (Fault Detection and Isolation) filters are very important and useful scheme for guaranteeing safety and reliability of realistic active control systems. The FDI filter design method based on the sliding mode observer proposed by Edwards provides desirable performances for detection of faults in comparison with other methods such as H_∞ filters, etc. However, the method can not be applied to a system which includes poles at the origin such as an attitude control system of a satellite. This paper proposes a method to avoid the problem of the poles and an application result to a satellite control system is provided. Furthermore, an idea of virtual sensor outputs is proposed for improvement of fault estimation performances.

View full abstract

In order to investigate the durability of sliding or rolling parts of machinery or to apply appropriate heat and surface treatment conditions to such parts, it is important to know the oil-film pressure and to evaluate the stress distribution of the parts. Regarding the contact pressure between the gear teeth flanks and cam followers, the maximum pressure and stress distribution can be calculated theoretically. However, the real contact pressure does not always agree with calculated ones due to the different configuration of contact surface, misalignment and etc. In this study, the authors developed a thin film pressure sensor with a thickness of 4.2μm, and the high oil-film pressure of the order of GPa under the line contact was measured. For the experiment, a test rig was developed with two-rollers to which a thin-film pressure sensor for the pressure measurement and additionally two-thin-film pressure sensors for checking the contact condition were deposited. The measured maximum pressure agreed comparatively well with Hertzian maximum pressure. Except the pressure spike, the measured pressure distribution also agreed rather well with the EHL calculation.

View full abstract

Validity in modeling systems depends on experiences of designers because validation processes have not been established. The authors propose a noise-adaptive system modeling procedure using a concept of Design Review Based on Failure Mode (DRBFM) as the validation process. The proposed procedure involves, (1) Detecting a difference by comparison between a design condition in an ideal model with that in practical one, (2) Setting Noise N_i caused by the difference, (3) Predicting an effect by the noise ε_i, (4) Inserting an additional element m(ε_i) in the model and (5) Checking whether other ε_i might exist. An experiment of modeling a robust model of a drain tube by university students using the proposed procedure or a normal process (FMEA) was conducted. Mean score of robustness of drains in a group using the proposed procedure was higher than that in the group using FMEA, which demonstrates the effectiveness of the proposed procedure.

View full abstract

We propose a new guide method for developing an easy-to-design process for product development. This process ensures a smaller number of wasteful iterations and less multiple conflicts. The design process is modeled as a sequence of design decisions. A design decision is defined as the process of determination of product attributes. A design task is represented as a calculation flow that depends on the product constraints between the product attributes. We also propose an automatic planning algorithm for the execution of the design task, in order to minimize the design loops and design conflicts. Further, we validate the effectiveness of the proposed guide method by developing a prototype design system and a design example of piping for a power steering system. We find that the proposed method can successfully minimize design loops and design conflicts. This paper addresses (1) a design loop model, (2) a design conflict model, and (3) how to minimize design loops and design conflicts.

View full abstract