Application of the Sliding-Mode Controller to Optical Disk Drives

Abstract

The transfer of an electron from a carbon nanotube (CNT) tip into vacuum under a high electric field is considered beyond the usual one-dimensional semi-classical approach. A model of the potential energy outside the CNT cap is proposed in order to show the importance of the intrinsic CNT parameters such as radius, length and vacuum barrier height. This model also takes into account set-up parameters such as the shape of the anode and the anode-to-cathode distance, which are generically portable to any modelling study of electron emission from a tip emitter. Results obtained within our model compare well to experimental data. Moreover, in contrast to the usual one-dimensional Wentzel-Kramers-Brillouin description, our model retains the ability to explain non-standard features of the process of electron field emission from CNTs that arise as a result of the quantum behaviour of electrons on the surface of the CNT.

Postfitting Control Scheme for Periodic Piezoscanner Driving

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Apply tapping mode Atomic Force Microscope with CD/DVD pickup head in fluid

“…In order to design a controller which can properly handle piezoelectric nonlinearity and system uncertainty, and meanwhile can gain high robustness and self-tuning property, we propose an adaptive sliding-mode controller for the tapping mode type AFM operation [20] [21]. To start with, a linear second order model can be used to represent the actuator's nominal dynamics: 1 0 z a z a z bu…”

High-Gain Servo Controller for Optical Disk Drives and the Initial Value Compensation

“…As optical disks are removable and have some distortions, servo systems must be made robust. Various control technologies have been studied (Miyazaki et al, 2003) (Takahashi et al, 2003), but they require large circuits or high power. We proposed the high-gain servo controller with complex zeros (Urakawa et al, 2004), which is the same 2 nd order controller as conventional controllers.…”