Active vibration control

About: Active vibration control is a research topic. Over the lifetime, 6770 publications have been published within this topic receiving 76599 citations. The topic is also known as: active vibration damping.

Fault-tolerant vibration control in a networked and embedded rocket fairing system

Abstract: Active vibration control using piezoelectric actuators in a networked and embedded environment has been widely applied to solve the rocket fairing vibration problem. However, actuator failures may lead to performance deterioration or system dysfunction. To guarantee the desired system performance, the remaining actuators should be able to coordinate with each other to compensate for the damaging effects caused by the failed actuator in a timely manner. Further, in the networked control environment, timing issues such as sampling jitter and network-induced delay should be considered in the controller design. In this study, a timing compensation approach is implemented in an adaptive actuator failure compensation controller to maintain the fairing system performance by also considering the detrimental effects from real-time constraints. In addition, time-delay compensation in the networked control system is discussed, which is able to reduce damaging effects of network-induced delays.

Vibration control of a cylindrical shell used in MRI equipment

Abstract: One major problem in magnetic resonance image (MRI) equipment is the high-level noise borne by the vibration of the cylindrical shell to support the coils for gradient magnetic fields. The vibration of the shell is excited by the Lorentz force between the pulse current applied to the coils and the main magnetic field. In order to suppress the noise inside the cylindrical shell, it is aimed to control the vibration of the shell. In this paper, simulation is carried out on the vibration control of the shell by using distributed piezoelectric actuators. The actuators produce a bending moment or an in plane force when pulse voltages are applied synchronously with the pulse current of the coils. Coupling of actuators and vibration modes, and parameter optimization are also discussed. The simulation results show that the vibration level is successfully reduced in the frequency range of 400-1200 Hz.

Vibration gyro sensor, combined sensor, and method for producing vibration gyro sensor

Abstract: A vibration gyro sensor is constructed as follows. Namely, a detecting piezoelectric/electrostrictive element 12, which detects displacement generated in a direction perpendicular to a direction of vibration of a vibrator 2 when the vibrator is rotated, is provided on a detecting section. The detecting section is constructed by an integrated fired product made of ceramics together with the vibrator 2 and a support base 4. The detecting section is constructed by a first plate-shaped section 6 which is more thin-walled than the vibrator 2 and which has its principal surface extending in the direction of vibration. The piezoelectric/electrostrictive element 12 is formed in an integrated manner on the first plate-shaped section 6 in accordance with a film formation method. Further, a thin-walled second plate-shaped section 8, which is provided for decreasing rigidity in the direction of vibration and facilitating the vibration for the vibrator 2, is formed in an integrated manner so that its principal surface extends in the direction perpendicular to the direction of vibration. Accordingly, it is possible to obtain the vibration gyro sensor made of ceramics having excellent sensitivity, in which the characteristics of the vibrator are scarcely affected by an ambient magnetic field, processing or machining can be easily performed, and the electric characteristics can be advantageously adjusted.