A design of fast‐locking without overshoot frequency‐locked servo system by fuzzy control technique

Abstract

In this paper, a Fuzzy Pulse Pump Controller (FPPC) is proposed to realize a Fuzzy‐Controlled Frequency‐Locked Servo system (FC‐FLS) for getting a fast locking response without overshoot. A prototype FC‐FLS is designed and built to assess the system performance. In comparison with the Frequency Pump Controller‐based FLS (FPC‐FLS) and Variable Slope Pulse Pump Controller‐based FLS (VSPPC‐FLS), the acquisition times of the FC‐FLS are improved over 40%. In particular, there is no overshoot in the FC‐FLS for any servo distance. This means that a fast‐locking FLS, without overshoot, has been successfully implemented as theoretical prediction.     

A microprocessor‐based electrohydraulic servo system

Abstract

A microprocessor‐based electrohydraulic servo system has been constructed and tested. It is implemented with an 8‐bit single‐chip microcomputer to control a hydraulic motor. The control algorithm is based on variable structure control principles. The experimental results show that the system is under good control and possesses a great potential for electrohydraulic servo control.     

Analysis and design of frequency‐controlled oscillator for frequency‐locked stepping position control system

Abstract

A frequency‐locked stepping position servo system (FLSPS) is presented. The proposed microprocessor‐based sloped‐varied frequency‐controlled oscillator (SVFCO) is designed to achieve nearly the same acquisition times for different position commands. The slope‐varied technique is to quickly position for long distance servo during the wide‐range control. The motion profiles for position locking are adaptively built according to the periodically sampled frequency error. No motion profiles are required to be pre‐installed in the controller. The system model is built for stability investigation and simulation. A design example is realized to verify the theoretical predictions. System simulation and experimentation confirm that the system acquisition times for short, middle, and long distance servos are very close to each other. In comparison with the corresponding traditional stepping position system, the acquisition times of the FLSPS are improved by 53% and 73%.     

Design of a double microprocessor‐based on‐line process control system

Abstract

A numerical technique for integrating the full Navier‐Stokes and diffusion equations through an initial value problem has been used to investigate the time development of a line buoyant source issuing in a density‐stratified environment. The basic physical features and some structures of the interactions of the motion at the intermediate mixing region are obtained. Results show that the stratification tends to inhibit the flow development of the buoyant source and to encourage the formation of a recirculatory vortex on the lower region near the source and the upper region.     

Passivity‐based adaptive position control for an induction motor

Abstract

This paper presents a passivity‐based composite adaptive control scheme for the position control of an induction motor. First, the dynamics of the induction motor are proved to be state strictly passive by the passivity theorem. Then, a composite adaptive estimation algorithm is designed to control the position of the induction motor and the global stability of the overall position control system is proved based on passivity instead of Lyapunov‐type arguments. The approach is robust with regard to variations of motor mechanical parameters and external load disturbances. Experimental results are provided to show that good position tracking capability can be obtained without knowledge of the rotor flux.     

A label‐based information flow control model for object‐oriented systems

Abstract

This paper proposes a label‐based information flow control model to prevent information leakage within object‐oriented systems. It offers the features of: (a) adapting to dynamic object state change, (b) adapting to dynamic role change, (c) preventing indirect information leakage, (d) detailing the control granularity to variables, (e) allowing purpose‐oriented method invocation, (f) controlling method invocation through argument sensitivity, (g) allowing declassification, and (h) allowing only trusted sources to write a variable.     

A frequency‐dependent droop scheme for parallel control of ups inverters

Abstract

This paper presents a frequency‐dependent droop scheme for paralleling UPS inverters with no control interconnection, so the inverters can be tightly connected with the load. At the fundamental frequency, the reference voltage of the inverter is generated as a reactor connected between the inverter and the load. The intention is to control the real and reactive power sharing of inverters with the Q‐V and P‐ω droop scheme employed in the power system without needing a true transfer reactor. At the harmonic frequency, the reference voltage is generated as a resistor connected between the inverter and the load. The intention is that the load harmonic current can be shared equally and the voltage waveform distortion will be low. Two 1KVA single‐phase inverters are designed and implemented, some simulation and experimental results are provided for demonstrating the effectiveness of the proposed approach.     

A study of the feature‐based digital image stabilization system

Abstract

This article presents a digital image stabilization scheme that uses image processing techniques to compensate for undesirable image jitter due to vehicle or platform vibration to obtain a stabilized image display. The developed digital image stabilization system is based on the image combination approach combined with advanced image selection, feature detection, feature matching and pre‐rotation processing to produce crisp images. Using the Sobel edge detector, we calculate the magnitude of edge response as the judgment criteria for image transformation. To demonstrate the validity of the proposed technique, experimental results are given for some synthetic images.     

A simple model‐based nonlinear control strategy for feedback linearizable nonlinear processes

Abstract

In this paper we propose a simple and novel model‐based nonlinear control strategy for feedback linearizable nonlinear processes. The nonlinear controller, called NLC, has a forward static nonlinear element and, if the relative degree of the process is greater than unity, a linear dynamic feedback path. The nonlinear static element is a modified hyperbolic function which involves two tunable parameters used to adjust the linear gain and saturation level of the NLC. The NLC parameters are determined to achieve a desired tracking transfer function of the form (K_cs + 1)/(1 + ?s) ^r+1 where K_c and ? are parameters relating to NLC controller settings and r the system's relative degree. The effectiveness and applicability of the proposed nonlinear control strategy are demonstrated through the controls of nonlinear chemical processes. Extensive simulation results show that the proposed nonlinear control strategy is a robust model‐based approach for the nonlinear control of dynamic processes.     

Combinatorial growth and analysis of Ti-In-Zn-O films deposited by radio‐frequency and direct-current magnetron co-sputtering system

The compositional dependence of co-sputtered Ti-In-Zn-O film properties was investigated by means of a combinatorial technique. The X-ray diffraction result showed that the amorphous Ti-In-Zn-O films were fabricated regardless of the Ti contents [Ti / (Ti + In + Zn), at.%] of 4.5-34.4 at.%. The surface of amorphous Ti-In-Zn-O film is quite smooth. The obtained surface roughness (R_RMS) values ranged from 0.5 nm to 1.7 nm. The superior resistivity of 3.8 × 10^− 4 Ω cm and the transmittance of 92% (at 550 nm) was obtained for the Ti-In-Zn-O film with the elemental composition ratio of 18.6/68.5/12.9 at.% [Ti/In/Zn, at.%]. The indium quantity actually could be reduced to as high as ~ 15 at.% compared to that of commercial indium tin oxide or indium zinc oxide having similar resistivity value of ~ 10^− 4 Ω cm. Overall, the amorphous Ti-In-Zn-O films may serve as a viable, low-cost alternative for flexible transparent conducting electrode applications.     

MFXRLS‐based adaptive feed‐forward controller implemented with velocity sensor identified by frequency response to improve actuator speaker performance in ANC systems

Abstract

To improve performance of a “dual voice coil” (DVC) actuator speaker in an active noise control (ANC) system, a speaker model that includes coupling dynamics and source of noise pressure is first derived to design an adaptive feed‐forward controller based on modified, filtered‐X, recursive‐least‐squares (MFXRLS) algorithm in this investigation. A novel velocity sensor measuring velocity of the speaker face is further developed by use of a frequency‐response method. Two transfer functions required for the velocity sensor are identified in two steps: (i) the adaptive feed‐forward controller is applied to keep speaker face velocity zero to identify the first transfer function; and (ii) the second transfer function is then obtained experimentally using the first transfer function. Performance of the established velocity sensor is similar to that of a Polytec OFV2100 laser velocity transducer. This velocity sensor is then incorporated with the adaptive feed‐forward controller to control the DVC actuator speaker in the ANC system. For a sinusoidal command input of frequency below 390 Hz, the controlled speaker acquires a unit‐gain magnitude and zero phase degree, showing that the controller can effectively reduce effects of the speaker dynamics, including coupling dynamics.