Switching inductive shunt damping technique is one of the most useful methods for structural vibration control due to its simplicity and robustness. In this paper, a method to design the inductance and the resistance in the shunt circuit is discussed. Initial response and harmonic response are especially considered in the design method. The design method is validated by simulation. Furthermore, switching shunt damping applied for a multi degrees of freedom system is examined using an experimental plate.
This paper investigate the properties of the impedance matching controller for the uniformly varying damped mass-spring systems and the resultant closed loop systems by invoking the properties of the algebraic function. The analyticity and the positive real property of the impedance matching controller are first investigated. Next, the internal stability of the feedback interconnection of the uniformly varying damped mass-spring system and the impedance matching controller is studied. Finally, the ladder structure of the closed loop system and the impedance matching controller is investigated.
This study considers active vibration control of a multi-story structure which consists of bar-connected masses repeated in the vertical direction with active mass drivers installed on the top. As an alternative to the vibration mode approach, the traveling wave approach is applied. To implement the impedance matching controller which is proposed for a damped mass-spring system, the loop shaping design procedure is used to consider the dynamics of the actuator and the sensor noise. The designed controller has similar properties of the impedance matching controller, that is, it is efficient for the disturbance at any position and the towers with any stories. Experimental results are shown to evaluate efficiency.
This paper considers wave analysis and control of two-dimensionally connected damped mass-spring systems. Considering two-dimensional field waves such as longitudinal vibration of plates and out-of-plane motion of membranes, mass motion in the longitudinal direction is considered. The system can be viewed as cascade connected layers composed of vertically connected elements. The system dynamics can be expressed by a recurrence formula. The eigenvalues of the coefficient matrix determine the propagation constants, and the eigenvector elements determine the characteristic admittances. It can be shown that the characteristic polynomial can be decomposed into second order polynomials, which reveals the properties of the propagation constants required for the wave analysis. It can also be shown that the characteristic admittance (impedance matching controller) is a positive real function, which guarantees the closed loop stability. A numerical example illustrates effectiveness of the impedance matching controller for vibration control.
This paper considers a method to determine a contact point location between two rigid bodies from a 6-axis force/moment sensor. In the noiseless case, it is well known that the contact point location can be determined directly by solving equations representing the force/moment balances for the exerted force and the resultant sensor signals. Although we can substitute measured signals to the solution whether noise exists or not, if noise exists, a minimizing solution to the error of force/moment balances will be preferable. In this paper, we formulate the estimation problem as a minimization problem of the weighted sum of the error of force/moment balances. The optimization problem is solved analytically and the solution is derived in a closed form. The solution for the noiseless case can be regarded as the minimizing solution for the error of moment balance by assuming that the force balance holds. The proposed method is also extended to the case where the measurement signals for multiple sampling instants can be used. A numerical example and experiments are shown to prove effectiveness of the proposed method.
This paper investigates wave-based analysis and impedance matching for the ladder electric networks. The results are a generalized version of our previous work for the cascade connected damped mass-spring systems. We first clarify the class of the ladder networks which satisfies the three conditions for the propagation constants to be analyzed by the wave-based analysis. Secondly, for the class of the networks, we investigate the analyticity of the secondary constants and positive real property of the characteristic impedances. Properties of the impedance matching are also investigated. A numerical example for a mechanical system shows effectiveness of the impedance matching for vibration control.
This paper considers the fault diagnosis for vibrating systems. An estimation method of the mode shapes by using independent component analysis is presented. The harmonic signal, impulse signal, and white noise are available for the input signals. The method only requires independence of the modal coordinates, and it does not require the physical parameters of vibrating systems and the inputs' information. In the numerical example, fault diagnosis for a plate is presented as an application of the proposed method.
This paper considers tensegrity structures constructed from a repetition of simple basic units. Considering to design plate-type structures, we choose a tensegrity prism as a unit. Connectivity matrix plays a central role in analysis and design of tensegrity structures. This paper provides a systematic way to construct the connectivity matrices of tensegrity structures constructed from a repetition of the tensegrity prisms. Number of the units and node location (shape) can also be chosen arbitrary. As an application of the connectivity matrix, a dynamical simulation of a tensegrity prism plate is shown.
Many industrial robot manipulators are driven by d. c. servomotors, where, in addition to gears, springs are used to connect each manipulator arm axis with the corresponding motor axis. In control aspects, the gear in those transmission parts is a positive factor because it suppresses nonlinear dynamics of the manipulator. However, the spring is a negative one ; it makes the joint flexible and causes residual vibration in the end point of the manipulator when the manipulator has to stop abruptly. In this paper we show that the H∞ controller is very effective to eliminate, or minimize to an acceptable level, the residual vibration. The robot manipulator considered in this paper is one with revolute joints (i. e., so-called PUMA type). First we describe the method of designing the H∞ controller, and then we confirm the effectiveness of this controller through experiments by comparison with a PD controller. The experimental results show that the H∞ controller can make the settling time of residual vibration much shorter than the PD controller, although the overshoot is rather large.
