Double-Boosted High-Gain Servo Controller for High-Rotation-Speed Optical Disk Drives

Abstract

We show that the 3D charged Banados-Teitelboim-Zanelli (BTZ) black hole solution interpolates between two different 2D AdS spacetimes: a near-extremal, nearhorizon AdS 2 geometry with constant dilaton and U(1) field and an asymptotic AdS 2 geometry with a linear dilaton. Thus, the charged BTZ black hole can be considered as interpolating between the two different formulations proposed until now for AdS 2 quantum gravity. In both cases the theory is the chiral half of a 2D CFT and describes, respectively, Brown-Hennaux-like boundary deformations and near-horizon excitations. The central charge c as of the asymptotic CFT is determined by 3D Newton constant G and the AdS length l, c as = 3l/G, whereas that of the near-horizon CFT also depends on the U(1) charge Q, c nh ∝ lQ/ √ G.

Full FPGA Tracking Control System Based on Error-Based Communication Disturbance Observer Considering Time Delay for Optical Disc System

“…A feedback control system without consideration of the time delay cannot be designed for the desired poles, since the closed-loop transfer functions cause model mismatching. The characteristic The time delay is shown as (5). In this paper, the non-integer time delay is expressed by using the Padè approximation (21) .…”

“…As the optical disc rotation speed increases, the periodic disturbances also increase. A feedback controller for suppressing the periodic disturbances has been proposed (3)- (5) . However, it is difficult to perfectly suppress periodic disturbances in a high-rotation disc system using a conventional feedback tracking control system.…”

Fine Tracking Control System based on Double Equivalent-Perfect Tracking Control System and Error-Based Disturbance Observer for Optical Disk

“…As in the case of a lead lag compensator, the HGSC combines a phase lead compensator and phase lag compensator, although it is also a controller capable of providing high gains at low frequencies. The HGSC is designed in accordance with the proposed method (14) (15) . The proposed design method allows the realization of a feedback controller having a sufficient gain margin and phase margin, while maintaining a high gain at a low frequency.…”

Stable Rotation of Optical Disks over 15000 rpm

“…The parameters of the double-boosted high-gain servo controller were designed by the pole assignment method to have sufficiently high gain at low frequency, similarly to the high-gain servo controller. 3,4) According to this method, the parameters were decided by designing the positions of the poles of the system. The system with the double-boosted high-gain servo controller had seven poles.…”

“…We also conducted an experiment on tracking servo control at high rotational speeds, and confirmed a robust servo control at 21000 rpm with a double-boosted high-gain servo controller. 3)…”