This paper describes a modeling and nonlinear control design method for a manipulator based on multibody dynamics (MBD). Each arm of the robot has seven degrees of freedom, similar to a human arm. The arm is a redundant manipulator, so it is generally difficult to control. To derive an accurate model of the robot arm, it is straightforward to set up three-dimensional equations of motion using MBD. We propose two controllers using the MBD model. One is an LQI controller with inverse dynamics. The other one is a nonlinear controller using the structure of the MBD model. We tested the effectiveness of our proposed method by a simulation and experiment. As the results, the tracking performance of the nonlinear controller based on the MBD model was about 18% better than the controller of the LQI controller with inverse dynamics.

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This paper describes a modeling method based on multibody dynamics (MBD) and autonomous control of a dual-arm robot with a stereo camera. Each arm of the robot has seven degrees of freedom, similar to a human arm. Even a robot with a lot of links, a model of the robot should be expressed fully that a check experiment can be done. One of MBD method can express the motion equation of a robot with a lot of links compactly. A model for our robot is derived by MBD. The robot controller consists of an LQI controller and gravity compensation. Gravity compensation is designed using the MBD model. The positions of objects to be manipulated are obtained using 3D color data obtained using a stereo camera. We tested the effectiveness of our proposed method by experiment. As a result, the tracking performance of the LQI controller with gravity compensation was about 21% better than that without gravity compensation.

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A golf swing robot is a kind of fast motion manipulator with a flexible link. A robot manipulator is greatly affected by Corioli's and centrifugal forces during fast motion. Nonlinearity due to these forces can have an adverse effect on the performance of feedback control. In the same way, ordinary state observers of a linear system cannot accurately estimate the states of nonlinear systems. This paper uses a state observer that considers disturbances to improve the performance of state estimation and feedback control. A mathematical model of the golf robot is derived by Hamilton's principle. A linear quadratic regulator (LQR) that considers the vibration of the club shaft is used to stop the robot during the follow-through action. The state observer that considers disturbances estimates accurate state variables when the disturbances due to Corioli's and centrifugal forces, and impact forces work on the robot. As a result, the performance of the state feedback control is improved. The study compares the results of the numerical simulations with experimental results.

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In this study, simple PI and fuzzy-sliding-mode controllers incorporating a memory-based learning control scheme are proposed to resolve tracking problem of a piezo-actuated system. Unlike traditional model-based approaches, which require precise inverse model in order to cancel out undesirable hysteresis effects, the methods proposed here are model-free. The proposed schemes are denoted as the learning-enhanced fuzzy sliding-mode control (LEFSMC) and learning-enhanced PI control (LEPIC) because a memory-based predictor is adopted to compensate for the hysteresis-induced tracking error. The learning scheme predicts the tracking error of the present cycle based on the knowledge of the previous tracking errors. The predicted tracking error is then used to update the control action and to serve as a learning enhancement to the traditional PI and fuzzy sliding-mode controller (FSMC). Experimental investigations focusing on different types of reference inputs show that the proposed control schemes may suppress the tracking error to within 5% full span range (FSR) of the actuator by using the LEFSMC and to within 6% FSR using the LEPIC.

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The application of a robust multivariable control to an electrodynamic multi-axis shaking system that is not permitted to employ an iteration control method is presented. The influences of a resonant specimen and a cross-coupling term are considered, and the robust controller is designed by using μ-synthesis. Because a redundancy arises from the fact that the 4-degree-of-freedom (DOF) shaking table is composed of five shakers, an undesirable high-gain controller may be obtained. A transformation matrix is then used to eliminate the redundancy. Furthermore, when an uncertainty for the resonant specimen is introduced, a parametric state-space uncertainty is considered because of the improvement in performance and the reduction of an order of the controller. Finally, the good performance of the controller is confirmed with the help of experiments conducted using the actual equipment with the resonant specimen.

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In the present paper, the motion of a tethered system with large deformation and large displacement is discussed. In general, a tether is a cable or a wire rope, and a tethered system consists of a tether and the equipment attached to the tether. A tethered subsatellite in space is an example of a tethered system. In the present study, a tethered system consisting of a very flexible body (the tether) and a rigid body at one end is considered as the analytical model. A flexible body in planer motion is described using the Absolute Nodal Coordinate Formulation. Using this formulation, the motion of a flexible body with large deformation, rotation and translation can be expressed with the accuracy of rigid body motion. The combination of the flexible body motion and the rigid body motion is performed, and their interaction is discussed.
Experiments are performed to investigate the fundamental motion of the tethered system and to evaluate the validity of the numerical formulation. Experiments were conducted using a steel tether and a rubber tether in gravity space. In addition, an experiment of the motion of the tethered system with a rigid body in microgravity space was conducted.

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A cylindrical hydraulic engine mount with simple construction has been developed. This engine mount has a sub chamber formed by utilizing air compressibility without a diaphragm. A mathematical model of the mount is presented to predict non-linear dynamic characteristics in consideration of the effect of the excitation amplitude on the storage stiffness and loss factor. The mathematical model predicts experimental results well for the frequency responses of the storage stiffness and loss factor over the frequency range of 5 Hz to 60Hz. The effect of air volume and internal pressure on the dynamic characteristics is clarified by the analysis and dynamic characterization testing. The effectiveness of the cylindrical hydraulic engine mount on the reduction of engine shake is demonstrated for riding comfort through on-vehicle testing with a chassis dynamometer.

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System control and identification often require accurate estimations of velocity and acceleration with a reduced group delay and low-pass property to attenuate high frequency noise. This paper proposes a novel design method of FIR filter for estimating velocity and acceleration from sampled displacement data, where the filter coefficients are derived by piecewise Radial Basis Function Network (RBFN). The proposed FIR filter not only provides more accurate estimates when compared to the conventional method, but also achieves the prescribed low-pass property and specified group delay in the pass band. The theoretical analysis of RBFN in the frequency domain reveals the relationship between the frequency response of the FIR filter and width/regularization parameters in the RBFN. Finally, the procedures for designing the filter are summarized with design examples.

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When a conducting plate moves through a nonuniform magnetic field, electromotive forces are induced in the conducting plate. According to Fleming's right-hand rule and left-hand rule, the induced currents produce a magnetic drag force. In these rules, a magnetic field perpendicular to the direction of movement generates a magnetic damping force. In the present work, we provide a possible resolution to the modeling of moving-conductor type eddy current dampers, using infinitesimal loop coils. Our model has three advantages: the equation of the magnetic damping force is simple; we can use the static magnetic field obtained by using the finite element method (FEM), the Biot-Savart law or experiments; and the model automatically satisfies boundary conditions. Using infinitesimal loop coils, we have modeled the magnetic damping force produced by a moving-conductor type eddy current damper composed of electromagnets and a conducting disk. Furthermore, the experimental setup has been fabricated, and damping ratios from experiments are compared to the analytical results and are found to be in good agreement with them.

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A colloidal damper is a damping element that has a novel structure which is fusing technology of mechanical engineering and nanotechnology. This structure is composed of cylinder and piston in which a mixture of hydrophobic porous matrix and liquid are inserted. If an external force impresses to the damper, the pressure in the cylinder increases, and then the liquid flows into the pores of porous matrix. In this time the surface extension force for compression is larger than that for relaxation. This difference of the surface extension force produces a damping energy.
The colloidal damper which was applied the difference of surface extension of compression and relaxation was first developed by Eroshenko. In his device the damper had colloidal liquid and oil in the bag in the cylinder, and damping characteristics and kinds of the colloid had not studied. A simple damper composed of piston and cylinder was made to investigate the basic static characteristics of the colloidal damper in our group. Then influence of hydrophobic coatings on dynamic characteristics and endurance of coatings of the silica gel were investigated. When the damper is used in practice, there are many applications. So, effect of size of the damper should be investigated. But effect of size on the damping has not been investigated. In addition, investigation for the single cylinder type damper has been mainly studied, but this type need bias pressure to have a damping force in the negative force range. In order to avoid this disadvantage, double cylinder type damper was developed. Then in this paper the relationship between the stroke and the pressure, the dissipative energy and the efficiency are investigated for the single colloidal damper and the double colloidal damper, and dynamic characteristics of these dampers were compared. Additionally, mass-spring-damper system in which the single colloidal damper is installed is designed for the suspension of a quarter of a car to demonstrate a practical use.

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Using the fully-enhanced variation of elastic potential energy the secondary extra elastic terms have been revealed in the dynamic model of a nonlinear 3D Euler-Bernoulli beam undergoing negligible elastic orientation. They have been sensed neither in the nonlinear 3D Euler-Bernoulli beam nor in the enhanced nonlinear 3D Euler-Bernoulli beam. They complete the issue of the new elastic terms of the enhanced nonlinear 3D Euler-Bernoulli beam. The whole of the extra elastic terms have been shown in the motion equations and the boundary conditions of a fully-enhanced nonlinear 3D Euler-Bernoulli beam undergoing negligible elastic orientation.

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This paper deals with a nonlinear surface and interface sloshing in layered two immiscible fluids of different desities. Scientific interest in surface and interface sloshing includes the need to quantify allowance loads on separators or agitators in chemical plants and so on. We propose the analytical method for nonlinear sloshing in this problem by using Hamiltonian formulation. In theoretical analysis, the governing equations and canonical form (Hamiltonian equations) of a system of two fluids with a dynamic free surface and interface are given by applying Hamilton's principle. Moreover, the nonlinear ordinary differential system which governs liquid surface and interfacial wave motions is derived by using Dirichlet-Neumann operators and the generalized Fourier series expansion. Solving these ordinary differential system yields the time histories and the transitions of surface and interfacial wave motions in a rectangular tank. The validly of the theoretical analysis is verified through the experiments.

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