Two robust nonlinear controllers along with a nonlinear observer have been developed in this study to control a 1D nonlinear flexible spacecraft. The first controller is based on dynamic inversion, while the second one is composed of dynamic inversion and µ-synthesis controllers. The extension of dynamic inversion approach to flexible spacecraft is impeded by the non-minimum phase characteristi...

The vibration control problem of offshore jacket platforms is studied. According to Morison equation, the total wave force acting on the offshore structure is obtained and is generated by an exosystem. Considering the nonlinear interaction of pile-soil, which is described by a fifth order anti-symmetric polynomial, the nonlinear dynamical model of offshore platforms affected by the wave load di...

Article history: Received: 06.02.2015. Received in revised form: 11.05.2015. Accepted: 15.05.2015. Due to the shortcomings of one mass vibration mill such as inefficiency, high energy consumption and big noise, a double mass high energy vibration mill, in which transient high vibration intensity is produced, is investigated by applying the non linear vibration theory. The nonlinear hard feature...

Currently, the interest in monitoring the vibration of dynamical systems has been increasing. For example, large and complex air and space structures include vibration monitoring systems to forecast sudden failures. Such vibration monitoring is used to diagnose structural health by analyzing vibration characteristics (such as frequency and amplitude). Among the vibration characteristics used, t...

Active control of sound and vibration has been the subject of a lot of research in recent years, and examples of applications are now numerous. However, few practical implementations of nonlinear active controllers have been realized. Nonlinear active controllers may be required in cases where the actuators used in active control systems exhibit nonlinear characteristics, or in cases when the s...

Motion-induced vibration can be greatly reduced by properly shaping the reference command. Input shaping is one type of reference shaping method that is based largely on linear superposition. In this paper we document the impact of nonlinear crane dynamics on the effectiveness of input shaping. As typical bridge cranes are driven using Cartesian motions, they behave nearly linearly for lowand m...

In this paper, we present nonlinear control algorithms to compensate for kinematic error in harmonic drives, thus forming a solid basis to improve their performance in precision positioning applications. Kinematic error, defined as deviation between expected and actual output positions, influences performance by producing static positioning error and inducing dynamic vibration effects. Its comp...

Cylindrical shells exhibit a dense frequency spectrum, especially in the lowest frequency range. In addition, due to the circumferential symmetry, frequencies occur in pairs. So, in the vicinity of the lowest natural frequencies, several equal or nearly equal frequencies may occur, leading to multiple internal resonances. The aim of the present work is to investigate the dynamic behavior and st...

Two elastically coupled nanomechanical resonators driven independently near their resonance frequencies show intricate nonlinear dynamics. The dynamics provide a scheme for realizing a nanomechanical system with tunable frequency and nonlinear properties. For large vibration amplitudes, the system develops spontaneous oscillations of amplitude modulation that also show period-doubling transitio...