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For human-centered automation, this study presents a wireless sensor network using predicted mean vote (PMV) as a thermal comfort index around occupants in buildings. The network automatically controls air conditioning by means of changing temperature settings in air conditioners. Interior devices of air conditioners thus do not have to be replaced. An adaptive neurofuzzy inference system and a particle swarm algorithm are adopted for solving a nonlinear multivariable inverse PMV model so as to determine thermal comfort temperatures. In solving inverse PMV models, the particle swarm algorithm is more accurate than ANFIS according to computational results. Based on the comfort temperature, this study utilizes feedforward–feedback control and digital self-tuning control, respectively, to satisfy thermal comfort. The control methods are validated by experimental results. Compared with conventional fixed temperature settings, the present control methods effectively maintain the PMV value within the range of \pm 0.5 and energy is saved more than 30% in this study. [ABSTRACT FROM PUBLISHER]

This paper proposes a novel linear electromagnetic actuator (LEA) for auto-focusing of compact phone cameras. An LEA consists of permanent magnets, iron cores, and coils, which are all magnetic circuit components. When coils are powered, induced magnetic field generates N and S poles around iron cores. Thus, unlike voice coil motors (VCMs) that employ the Lorentz force, the motion of the moving part in this study is arisen from a property-same poles repel each other while opposite poles attract each other. When compared to conventional VCM actuators in simulation results, the proposed LEA generates larger force, whereas using smaller current. [ABSTRACT FROM AUTHOR]

The latest research in optical image stabilization actuators (OISA) focuses on improving the image quality of high resolution cameras in a photographing optical system (POS). The focal image blur is always caused of external and environmental jitter when pictures of an image sensor are acquired by photographers. Several works concerned for OISA are emphasized mainly OISA design methods; consequently, they are devoted to minimizing dimensions and maximizing driving magnetic force with low power consumption. Although two proportional-integral-derivative controllers and lead-lag compensators have been proposed to position dual axes of OISA in a POS, they lack robustness to compensate nonuniform friction, system uncertainty, and external disturbance. Therefore, this work aims at the sliding mode control (SMC) using virtual eigenvalue method to achieve fast time response and accurate position despite vibration from external jitter and friction of a compact OISA. The sliding surface can be reached in finite time to match disturbance. Accordingly, the SMC algorithm works well despite system uncertainty and external disturbance, and then the time response of simulation and experiment are matched. In consequence, the settling time of dual axes are converged within 0.2 s when the dual axes of movable platform of a compact OISA move at 0.5 mm stroke in a POS. [ABSTRACT FROM AUTHOR]

This paper proposes a wavelet network control method to online learn and cancel repetitive errors in disk drives. In contrast to Fourier transforms, wavelet transforms can provide detailed local information of signals. Based on the wavelet transform, wavelets can approximate any finite energy function. This paper proposes wavelet networks to approximate periodic functions. Accordingly, a wavelet network controller is developed to eliminate repetitive error caused by repetitive disturbance. Experiments for flying height control of a disk drive system are implemented to demonstrate the present method in comparison with another method using Fourier series based network control. [ABSTRACT FROM AUTHOR]

The output feedback sliding mode control offers an effective positioning method by robustness to parameter variation and disturbance rejection. This paper presents the output feedback sliding mode control based on a position estimation algorithm written in the microprocessor for use in the focusing control system of a digital video camera to achieve fast focusing response and accurate positioning despite vibration and friction of the movable part of the linear focusing actuator. The focusing performance by utilizing the output feedback sliding mode control includes a 60-ms setting time and 7-μm steady-state error, respectively, which are only half and one-third of those in proportional-integral-derivative control when the movable part of the linear focusing actuator moves at a 5-mm stroke. [ABSTRACT FROM AUTHOR]

Unbalanced disks in rotation will lead to the main vibration of an optical disk drive. Passive vibration absorbers are usually used in current optical disk drives to suppress vibration. Generally, optical disk drives have to make a disk spin at multiple speeds by different read/write conditions. However, the passive vibration absorber only suppresses vibration at a specific rotating speed and may excite vibration at other speeds. This paper uses a linear quadratic Gaussian (LQG) controller for active vibration absorbers to reduce disk-drive vibration at multiple rotating speeds. The absorber with LQG control is validated based on simulation and experimental results. [ABSTRACT FROM AUTHOR]

A near-field optical disk drive uses near-field optics to read/write disk data at a flying height of about 50 nm. Effects of interfacial adhesive forces, including van der Waals forces and electrostatic forces, become more evident during ultralow flying. However, the pickup head-flying-height variation is affected by the suspension, disk flutter, and air flow between the flying head and disk. An analysis model consisting of a simplified suspension and an air-bearing model with springs and dampers in three directions (focusing, pitching, and rolling) is used to simulate the dynamic behavior of the flying head. This study proposes an improved method for measuring the slider's flying-height variation. Simulation results with and without interfacial adhesive forces are compared. [ABSTRACT FROM AUTHOR]

The slider of a flying pickup head in a near-field optical disk drive has to fly at a stable height above the disk surface. An air bearing force between the slider and optical disk is affected by disk rotation speed and deformation, which represent low-frequency periodic disturbance to the slider. The repetitive control is adopted in this study to eliminate the periodic disturbance. H∞ control inherited with robust properties can deal with model uncertainty and disturbances. Therefore, to solve model uncertainty and disturbance, this study designs a repetitive controller cascaded by an H∞ controller, The proposed controller is validated by experimental results. [ABSTRACT FROM AUTHOR]

To achieve stable flying height of a pickup head in near-field optical disk drives, this study investigates a discrete sliding mode control with a frequency-shaped sliding surface. A compensator is introduced in a sliding mode using a frequency-shaped performance index with linear quadratic optimal and sliding mode control. As an actuator, a piezoelectric bender is used in this. study to complement an air bearing at the head/disk interface. Experiments are carried out to demonstrate that the proposed controller performs better in flying height control than an optimal sliding mode controller. Accordingly, the controller can achieve stable flying height control in the presence of certain frequency vibration of optical disks. [ABSTRACT FROM AUTHOR]

To achieve stable flying height of a pickup head in near-field optical disk drives, the influence of disk grooves on the airflow of an air bearing deserves investigation, since at a very low flying height, groove geometry is comparable to the flying height. This paper aims to compare air bearing airflows between near-field optical disks with grooved surface and conventional disks without grooved surface. Computational results show that grooved disks generate smaller pressure than S both disks since grooves can accommodate air molecules and tune air pressure. Flying higher makes pressure magnitudes closer between grooved disks and smooth disks in negative pressure area On slider bottoms. Further, track pitches and groove depths essentially do not affect pressure at rails. [ABSTRACT FROM AUTHOR]