scholarly journals Noninteracting Control Design for 6-DoF Active Vibration Isolation Table with LMI Approach

2021 ◽  
Vol 11 (16) ◽  
pp. 7693
Author(s):  
Dong-Hun Lee ◽  
Young-Bok Kim ◽  
Soumayya Chakir ◽  
Thinh Huynh ◽  
Hwan-Cheol Park
Keyword(s):  
Degrees Of Freedom ◽  
Vibration Isolation ◽  
Reference Signal ◽  
Good Control ◽  
System Stability ◽  
Linear Matrix ◽  
Effective System ◽  
System Output ◽  
Active Vibration ◽  
Active Vibration Isolation

This paper proposes a novel control strategy for six degrees-of-freedom active vibration isolation tables. In these systems, the most challenging issue is to suppress the external vibrations and isolate the internal interactions while still preserving the system’s robustness when facing uncertainties. A noninteracting controller is designed to tackle these problems. The resulting control system is completely decoupled in the sense that each system output is independently controlled to follow the corresponding reference signal. In this paper, the model of an active vibration isolation table is firstly derived. Conditions for system stability and decoupled performance are then discussed. The control law is formulated using the linear matrix inequality approach, which results in optimal control gains for the control objectives. With the proposed controller, complex system characteristics can be handled more efficiently such that an effective system is designed to obtain good control performance. Finally, simulations and comparison studies were conducted, and the results validate the efficiency of the proposed scheme.

Gain-Scheduled ℋ∞-Control for Active Vibration Isolation of a Gyroscopic Rotor

2015 ◽  
Author(s):  
Fabian B. Becker ◽  
Martin A. Sehr ◽  
Stephan Rinderknecht
Keyword(s):  
Degrees Of Freedom ◽  
Vibration Isolation ◽  
Linear Time ◽  
Displacement Sensors ◽  
Active Vibration ◽  
And Performance ◽  
Gyroscopic Effects ◽  
Gain Scheduled ◽  
Active Vibration Isolation

This paper deals with active vibration isolation of unbalance-induced oscillations in rotors using gain-scheduled H∞-controller via active bearings. Rotating machines are often exposed to gyroscopic effects, which occur due to bending deformations of rotors and the consequent tilting of rotor disks. The underlying gyroscopic moments are proportional to the rotational speed and couple the rotor’s radial degrees of freedom. Accordingly, linear time-varying models are well suited to describe the system dynamics in dependence on changing rotational speeds. In this paper, we design gain-scheduled H∞-controllers guaranteeing both robust stability and performance within a predefined range of operating speeds. The paper is based on a rotor test rig with two unbalance-induced resonances in its operating range. The rotor has two discs and is supported by one active and one passive bearing. The active support consists of two piezoelectric stack actuators and two collocated piezoelectric load washers. In addition, the rig is equipped with four inductive displacement sensors located at the discs. Closed-loop performance is assessed via isolation of unbalance-induced vibrations using both simulation and experimental data. This contribution is the next step on our path to achieving the long-term objective of combined vibration attenuation and isolation.

Semi-Active Vibration Isolation Control for Multi-Degree-of-Freedom Structures

2002 ◽  
Author(s):  
Hidekazu Nishimura ◽  
Yasuhiko Okumura ◽  
Seiji Shimodaira
Keyword(s):  
Vibration Isolation ◽  
Linear Time ◽  
Design Method ◽  
Linear Matrix ◽  
Orifice Area ◽  
Convex Interpolation ◽  
Active Vibration ◽  
Active Damper ◽  
Gain Scheduled ◽  
Active Vibration Isolation

In this paper, we propose a design method of a controller for semi-active vibration isolation. We introduce a mechanism of a semi-active damper, which can change the damping in the ratio of the orifice area, in order to obtain the parameter-varying system model. Consideration of the semi-active damper mechanism is appropriate for the design of the gain-scheduled (GS) controller based on linear matrix inequalities (LMIs). The GS controller consists of four-vertex linear time-invaxiant controllers are obtained by the convex interpolation of these controllers. The designed controller switches at zero velocity of the damper and varies according to both the orifice area and the relative velocity of the isolation layer. By carrying out simulations, it is shown that our proposed method is effective for the suppression of seismic response.

scholarly journals Active Vibration Isolation of a Diesel Generator in a Small Marine Vessel: An Experimental Study

2020 ◽  
Vol 10 (9) ◽  
pp. 3025
Author(s):  
Tiejun Yang ◽  
Lei Wu ◽  
Xinhui Li ◽  
Minggang Zhu ◽  
Michael J. Brennan ◽  
...  
Keyword(s):  
Vibration Isolation ◽  
Feedforward Control ◽  
Reference Signal ◽  
Electrical Circuit ◽  
Diesel Generator ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Active Vibration ◽  
Adaptive Feedforward ◽  
Active Vibration Isolation

An active vibration isolation system is retrofitted to a diesel generator set in a tugboat to determine the effectiveness of such a system in a realistic practical environment. The system consists of six bespoke inertial actuators chosen to make minimal modifications to the machinery arrangement, and a DSP-based controller. Six accelerometers are collocated with the actuators on the top of six isolators to act as error sensors, and six accelerometers are placed below the isolators to give a measure of the global vibration of the ships structure below the generator set. A hydrophone is also placed in the water to give an indication of the underwater noise due to the generator. The control strategy employed is six-input and six-output decentralized adaptive feedforward control with the reference signal being derived from the signal from an optical tachometer on shaft between the engine and the generator. To suppress the vibration at all the dominant forcing frequencies, an electrical circuit generated the half engine orders required from the measured reference signal. The experimental results show that the combination of the active control system and the passive isolators is effective in reducing the global vibration and the acoustic pressure at the hydrophone position.

scholarly journals Tilt Active Vibration Isolation Using Vertical Pendulum and Piezoelectric Transducer with Parallel Controller

2021 ◽  
Vol 11 (10) ◽  
pp. 4526
Author(s):  
Lihua Wu ◽  
Yu Huang ◽  
Dequan Li
Keyword(s):  
Piezoelectric Transducer ◽  
Vibration Isolation ◽  
Vertical Vibration ◽  
Open Loop ◽  
Negative Effects ◽  
Voltage Controller ◽  
Hysteresis Nonlinearity ◽  
Passive Vibration Isolation ◽  
Active Vibration ◽  
Active Vibration Isolation

Tilt vibrations inevitably have negative effects on some precise engineering even after applying horizontal and vertical vibration isolations. It is difficult to adopt a traditional passive vibration isolation (PVI) scheme to realize tilt vibration isolation. In this paper, we present and develop a tilt active vibration isolation (AVI) device using a vertical pendulum (VP) tiltmeter and a piezoelectric transducer (PZT). The potential resolution of the VP is dependent on the mechanical thermal noise in the frequency bandwidth of about 0.0265 nrad, which need not be considered because it is far below the ground tilt of the laboratory. The tilt sensitivity of the device in an open-loop mode, investigated experimentally using a voltage controller, is found to be (1.63±0.11)×105 V/rad. To compensate for the hysteresis nonlinearity of the PZT, we experimentally established the multi-loop mathematical model of hysteresis, and designed a parallel controller consisting of both a hysteresis inverse model predictor and a digital proportional–integral–differential (PID) adjuster. Finally, the response of the device working in close-loop mode to the tilt vibration was tested experimentally, and the tilt AVI device showed a good vibration isolation performance, which can remarkably reduce the tilt vibration, for example, from 6.0131 μrad to below 0.0103 μrad.

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