Design of Active Vibration Isolation Controller with Disturbance Observer-Based Linear Quadratic Regulator for Optical Reference Cavities

Abstract

The optical reference cavity in an ultrastable laser is sensitive to vibrations; the microvibrations in a space platform affect the accuracy and stability of such lasers. In this study, an active vibration isolation controller is proposed to reduce the effect of vibrations on variations in the cavity length and improve the frequency stability of ultrastable lasers. Based on the decentralized control strategy, we designed a state-differential feedback controller with a linear quadratic regulator (LQR) and added a disturbance observer (DOB) to estimate the source noise. Experiments were conducted using an active vibration isolation system; the results verified the feasibility and performance of the designed controller. The accelerations along the axis (Z-, X-, Y-) directions were suppressed in the low-frequency band within 200 Hz, and the root-cumulative power spectral densities (PSDs) declined to 1.17 × 10−5, 7.16 × 10−6, and 8.76 × 10−6 g. This comprehensive vibration met the requirements of an ultrastable laser.

Advanced Vibration-Based Fault Diagnosis and Vibration Control Methods

“…This Special Issue on “Advanced Vibration-Based Fault Diagnosis and Vibration Control Methods” includes twelve papers ranging across different methods used in the electrical and mechanical industries’ systems. The papers include a good literature review of the current new works on the verification of mechanical properties identification based on the impulse excitation technique and mobile device measurements [ 4 ], the method for bearing fault diagnosis under variable speeds based on envelope spectrum fault characteristic frequency band identification [ 5 ], the interface design of head-worn display applications for condition monitoring in aviation [ 6 ], color recurrence plots for bearing fault diagnoses [ 7 ], the failure mode detection and validation of a shaft-bearing system with common sensors [ 8 ], the strain response and buckling behavior of composite cylindrical shells subjected to external pressure with one end fixed and the other free of boundary conditions [ 9 ], the smartphone-based and data-driven superstructure state prediction method for highway bridges in service [ 10 ], the optimal control algorithm for stochastic systems with parameter drift [ 11 ], the nonlinear vibration control experimental system design of a flexible arm using interactive actuations from shape memory alloy [ 12 ], the design of an active vibration isolation controller with a disturbance observer-based linear quadratic regulator for optical reference cavities [ 13 ], the applicability of touchscreens in manned/unmanned aerial vehicle cooperative missions [ 14 ], and the engineering frequency domain analysis and vibration suppression of flexible aircraft based on an active disturbance rejection controller [ 15 ].…”

“…The suppression of microvibrations based on vibration isolation systems is important. Qian et al [ 13 ] proposed an active vibration isolation controller to reduce the effect of vibrations on the variations in cavity length and improve the frequency stability of ultrastable lasers. They designed a state-differential feedback controller with a linear quadratic regulator.…”

Performance Analysis of Learning-Based Disturbance Observer for Pulsed Superconducting Cavity Field Control

“…DOB is a powerful technique for estimating and compensating for external disturbances without utilizing additional sensors. It has been widely used in many applications including in quad-copters [16,17], lasers [18], UAVs [19], and robotics [20]. DOB problems can be formulated and solved using transfer functions, state space equations and input-output data sets used for modeling systems in the framework of data-driven approaches.…”

Mechatronic Design of A Composite Vibration Isolation System

“…Active vibration isolation was suggested for enhancing the system reliability of ultra-stable lasers. The e ciency of the developed controller was con rmed experimentally [12]. A comparison between acceleration feedback and force feedback was established for vibration isolation in precision equipment.…”