Application of an active electromagnetic vibration absorber in vibration suppression

Abstract

A novel active electromagnetic vibration absorber (AEMVA) is developed. It is shown that for suppression of steady-state response to a harmonic excitation, a proportional and derivative feedback control is equivalent to a time-delayed control. The study of the stability issue focuses on a conflicting goal of achieving the marginal stability of the time-delayed vibration absorber and the stability of the combined system. The achievability of the ideal performance of the time-delayed vibration absorber is investigated. An experimental study is conducted to test the proposed AEMVA. An online tuning algorithm is proposed. The experimental results show that with the proposed tuning strategy, the AEMVA can maximize the vibration suppression while maintaining the system stability.both passive and active systems. On the one hand, they preserve the reliability of passive control systems in the event of power loss; on the other hand, they require less power to achieve the adaptability of active control systems.Usually, semi-active control devices achieve the adaptability by adjusting their mechanical properties, such as the stiffness and/or the damping value, through a feedback system. Several stiffness-variable vibration absorbers have been proposed in the literature. Stiffness variation of the device reported in [11] was achieved by varying the effective number of coils in a helical spring used as the absorber stiffness. The semi-active control device proposed in [12] consists of a flexible cantilever beam attached to a mass at its free end. By varying the length of the beam, the absorber frequency can be varied. The device reported in [13] is formed by four coil springs arranged in a planar rhombus configuration whose aspect ratio can be varied by a linear electromechanical actuator. It is noted that all the semi-active devices mentioned above involve an electromechanical-driven system. As a result, a slow action may become the main concern for this type of devices. Alternatively, damping is sometimes added to the absorber systems to prevent resonance and/or to improve the effective bandwidth of operation. Damping value can be made online adjustable by utilizing a variable-orifice valve to alter the resistance to the flow of a conventional hydraulic fluid damper [14]. Most noticeably, electro-rheological or magnetorheological dampers feature a broad-bandwidth modulation of the damping characteristics through the variation in the electrical or magnetic field [15][16][17][18].Compared with mechanical or hydraulic devices, electromagnetic devices possess some unique advantages such as cleanness, faster response time, no mechanical contact, easy integration with control system, compactness, etc. Therefore, the use of electromagnetic means in vibration control has been receiving a considerable attention. The active mass damper used in [19] was formed by a coil and a pair of permanent magnets (PMs). In [20], a voice coil motor was used to obtain an active vibration absorber. In [21], a shunted electromagnetic transducer was c...

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