INPUT‐STATE LINEARIZATION OF A ROTARY INVERTED PENDULUM

The aim of this paper is to design a nonlinear controller for the rotary inverted pendulum system using the input‐state linearization method. The system is linearized, and the conditions necessary for the system to be linearizable are discussed. The range of the equilibriums of the system is also investigated. Further, after the system is linearized, the linear servo controllers are designed based on the pole‐placement scheme to control the output tracking problem. The performance of the controller is studied with different system parameters. The computer simulations demonstrate that the controller can effectively track the reference inputs.     

烟尘微粒流速和质量浓度的测试研究

探讨光与烟尘流体微粒相互作用下传感器的输出与烟尘浓度和流速的关系特性,设计应用了光纤传感器测试系统,实验表明:在一定范围内输出与浓度和流速成线性关系。     

A mercury‐free backlight with Xe CFLs for automotive navigation displays

Abstract— A mercury‐free backlight in which Xe‐type small‐diameter CFLs were installed has been developed. The backlight is 7 in. wide and 10 mm thick. The luminance of this backlight is 6000 cd/m² at 6.5 W, the light‐output stability time is within 1 sec, and the dimming capability is from 100% to 1% over a wide temperature range. Therefore, it is suitable for an automotive‐navigation display.     

Current‐mode ambient‐light sensing circuit using p‐type low‐temperature polycrystalline‐silicon TFTs and p‐i‐m diodes

Abstract— A current‐mode ambient‐light sensing circuit, which is composed of p‐intrinsic‐metal (p‐i‐m) diodes and p‐type low‐temperature polycrystalline‐silicon (LTPS) thin‐film transistors (TFTs) for autobrightness control of display panels. The proposed sensing circuit exhibits a wide dynamic range of 56 dB, while the output signal range is 1.8 times wider than that of a previously reported sensing circuit.     

Efficient FPGA implementation of homodyne-based time-of-flight range imaging

Time-of-flight range imaging systems illuminate a scene with an amplitude-modulated light source, the light is reflected from objects in the scene, and measurement of the phase of the modulation envelope is performed to determine the object’s distance. As the image sensor is capable of performing this task for every pixel simultaneously, acquisition of the entire scene can be performed at rapid (video) update rates, making the technology ideal for real-time applications. In this paper we present an efficient real-time FPGA algorithm for determining phase, and hence distance, from the raw image sensor output. The algorithm has been implemented on a range imaging system based on the PMD19k-2 image sensor, with range processing performed in real time by a Stratix III FPGA. The scarcest resource in this implementation is RAM, and an analysis is presented to maximise the efficiency of this resource whilst maintaining acceptable processing accuracy. The algorithm can be extended for processing multiple simultaneous modulation frequencies. An efficient method for combining these results to determine unambiguous range, based on the Chinese remainder theorem, is also presented.     

A delay‐independent output feedback for linear systems with time‐varying input delay

It is well known that a delay‐dependent or delay‐independent truncated predictor feedback law stabilizes a general linear system in the presence of a certain amount of input delay. Results also exist on estimating the maximum delay bound that guarantees stability. In the face of a time‐varying or unknown delay, delay‐independent feedback laws are preferable over delay‐dependent feedback laws as the former provide robustness to the uncertainties in the delay. In the light of few results on the construction of delay‐independent output feedback laws for general linear systems with input delay, we present in this paper a delay‐independent observer–based output feedback law that stabilizes the system. Our design is based on the truncated predictor feedback design. We establish an estimate of the maximum allowable delay bound through the Razumikhin‐type stability analysis. An implication of the delay bound result reveals the capability of the proposed output feedback law in handling an arbitrarily large input delay in linear systems with all open‐loop poles at the origin or in the open left‐half plane. Compared with that of the delay‐dependent output feedback laws in the literature, this same level of stabilization result is not sacrificed by the absence of the prior knowledge of the delay.     

Projection‐based head‐tracking 3‐D displays

Abstract— This paper describes the construction and operation of four 3‐D displays in which each display produces two images for each eye and thus fits into the category of projection‐based binocular stereoscopic displays. The four 3‐D displays described are pico‐projector‐based, liquid‐ crystal—on—silicon (LCOS) conventional projector‐based, 120‐Hz digital‐light‐processor (DLP) projector‐ based, and the HELIUM3D system. In the first three displays, images are produced on a direct‐view LCD whose conventional backlight is replaced with a projection illumination source that is controlled by a multi‐user head tracker; novel steering optics direct the projector output to regions referred to as exit pupils located at the viewers' eyes. In the HELIUM3D display, the image information is supplied by a horizontally scanned, fast, light valve whose output is controlled by a spatial light modulator (SLM) to direct images to the appropriate viewers' eyes. The current statu s and the multimodal potential of the HELIUM3D display are described.     

大功率智能RGB-LED照明系统的设计

为了满足现代照明市场的需求,设计了一款基于Android Apps控制的RGB-LED智能照明系统.该系统采用了PFC与谐振半桥联合的控制器及其共享的反馈补偿回路,通过WiFi模块与单片机、Android Apps提供可智能控制的PWM,BUCK芯片通过接收不同占空比的脉冲波形来改变输出的电流,从而实现LED灯亮度的调节.又由于不同亮度的三基色灯光可以合成自然界中的任意色光,所以该系统可以实现任意色光的合成.此设计节省了成本,提升了效率、控制精度和调光范围.通过Android Apps的功能测试,完全实现了RGB-LED灯的调光调色和情景模式的智能变换.     

短距离LED可见光音频传输系统设计

基于白光LED照明和通信双重作用,构建了一种短距离白光LED可见光音频传输系统。从短距离、低功率系统考虑,分析可见光传输模型和影响因素,设计可行的可见光发射端和接收端。采用AGC电路和限幅放大电路提高系统的动态范围,保证语音信息输出稳定;采用阵列接收方式扩大接收角,提高系统灵敏度。为了实现系统噪声匹配,设计了低噪声高增益前置放大器。测试结果表明,系统实现了可见光短距离音频信息的无失真传输,验证了系统的可行性。     

基于ADuC7028的LD泵浦掺钕钒酸钇固体激光器控制系统的设计

设计了一种基于ADuC7028的LD(激光二极管)泵浦的掺钕钒酸钇固体激光器(Nd:YVO4)的控制系统.采用积分分离的数字PID温度控制,并结合功率反馈控制,根据LD驱动电流、激光工作温度与输出光功率三者之间的关系,找寻激光的最佳工作温度.在最佳工作温度下,激光具有较高的电光转换效率.实时监测激光输出功率的稳定性并进行温度的反馈调节,使激光输出功率的稳定性有了很大的改善.     

A novel lens cap designed for the RGB LEDs installed in an ultra‐thin and directly lit backlight unit of large‐sized LCD TVs

Abstract— The objective of this study is to design a novel cone‐shaped lens cap on LEDs in order to achieve high optical efficiency in an ultra‐thin directly lit RGB LED backlight unit (BLU) for large‐sized LCD TVs. The use of the novel lens cap could play the role of a diffuser, a low light‐efficiency component in a BLU, in order to gain higher efficiency and simultaneously provide satisfactory uniformity in light distribution. The novel cone‐shaped lens is coated with aluminum on the outside surface of the cone for mirroring effects to reflect most of the LED emitted light horizontally and then reflect the light at the BLU boundaries, and then, finally to the output plane. In this way, bright spots on the output plane of the BLU can be avoided, leading to increased uniformity. Simulations were conducted to design and optimize varied aspects of the designed lens and BLU, including the cone angle of the proposed lens and the LED spacing (pitch). To further achieve color balance, a known Genetic Algorithm is used to search for the optimal angular placement of each RGB LED, resulting in better color balance. Finally, a prototype BLU for large‐sized 37‐in. LCD TVs with the proposed lens was built to verify the expected performance.     

Optical CMOS sensor system for detection of light sources

An integrated silicon colour measurement system has been designed for low-cost measurement of ambient light conditions, which can be used for adaptive control of displays in portable instruments, or for testing the intensity or colour temperature of light sources. The system is CMOS compatible and has a bitstream output. The response of two vertically stacked photodetectors with a different spectral response are sequentially available at the output. It is demonstrated that daylight can be clearly distinguished from several other light sources, such as incandescent lamps and fluorescent lamps.     

Roll‐to‐roll UV embossing process applied for light bar‐based sub‐wavelength gratings for backlight

This study proposes a roll‐to‐roll process‐based sub‐wavelength grating, which is attached on a light bar to turn the side‐lit red/green/blue (620, 520, and 450 nm) incident rays into a uniformly and normally output white light with high illuminance from the light bar's surface. On the basis of the rigorous coupling wave analysis, the relationship between the first‐order transmission/reflection efficiency and the pitch of the gratings with different shapes was analyzed. The optimal design can effectively reduce the coupling length and enhance the white color balance for display applications.     

Passive multiplexing of printed electroluminescent displays

Abstract— A method is required for creating a graphics display, or pixel array, from printed electroluminescent (PEL) display technology and driving it efficiently and cost effectively. The display is made up of a matrix of capacitive light‐emitting display elements which are to be driven by a passive multiplexing method. A four‐level drive system is required in order to produce the best possible contrast ratio on the display. A four‐level drive system is costly to implement at the high voltages at which PEL displays operate, but a system is presented here which is able to make a significant reduction in the amount of electronics required to control the display. By selectively switching the output from a fly‐back power supply to different parts of the matrix display, the optimum voltages can be obtained across all segments from a single high‐voltage power supply. This provides potential for using passive‐matrix PEL displays in a wide variety of applications, as well as having possible applications for other display technologies such as PDLCs (see demonstration in Fig. 1).     

Green laser sources optimized for highly efficient microdisplay‐based field‐sequential mobile projectors

Abstract— A novel green laser source, based on a monolithic cavity microchip laser platform, has been developed. The laser is designed to be a part of a miniature and efficient RGB light source for microdisplay‐based mobile projector devices. The use of highly efficient, periodically poled MgO‐doped lithium niobate as the non‐linear frequency doubler allows for a significant increase in the overall efficiency of the green microchip laser. Specifically, a 50–150‐mW green output with a wall‐plug efficiency exceeding 10% in the temperature range of greater than 40°C has been demonstrated. A compact package for this laser source with a volume less than 0.33 cm³ is discussed and results of performance tests are presented.     

利用扭转高双折射光纤实现波长解调的方法

提出了一种基于扭转高双折射光纤实现光纤光栅波长解调的新型解调系统,对高双折射光纤光栅扭转特性进行了详细的理论推导,给出了数学表达式.通过计算机仿真发现系统输出光强与高双折射光纤扭转角度成标准余弦关系,扭转角度和时输出的光强的比值与波长近似呈线性关系.实验表明,系统具有10 nm的准线性解调范围,与理论分析相吻合.     

Output‐feedback tracking in causal nonminimum‐phase nonlinear systems using higher‐order sliding modes

Asymptotic output‐feedback tracking in a class of causal nonminimum phase uncertain nonlinear systems is addressed via sliding mode techniques. Sliding mode control is proposed for robust stabilization of the output tracking error in the presence of a bounded disturbance. The output reference profile and the unknown input/disturbance are supposed to be described by unknown linear exogenous systems of a given order. Local asymptotic stability of the output tracking error dynamics along with the boundedness of the internal states are proven. The unstable internal states are estimated asymptotically via the proposed multistage observer that is based on the method of extended system center. A higher‐order sliding mode observer/differentiator is used for the exact estimation of the input–output states in a finite time. The bounded disturbance is reconstructed asymptotically. A numerical example illustrates the efficiency of the proposed output‐feedback tracking approach developed for causal nonminimum phase nonlinear systems. Copyright © 2009 John Wiley & Sons, Ltd.     

Adaptive output feedback control for a class of nonlinear uncertain systems with quantized input signal

In this paper, adaptive output feedback control for a class of nonlinear systems with quantized input is investigated. The nonlinearities of the nonlinear systems under consideration are assumed to satisfy linear growth condition on the unmeasured states multiplied by unknown growth rate and output polynomial function. By developing a dynamic high‐gain observer, a linear‐like output feedback controller is constructed, with which it is proved that the output of the quantized control system can be steered to within an arbitrarily small residual set while keeping all the other closed loop states bounded. In particular, if the growth rate is known, it is proved that all the states of the system can be steered to within an arbitrarily small neighborhood of the origin. Copyright © 2016 John Wiley & Sons, Ltd.     

Linearly polarized light‐emitting backlight

A new polarized backlight system for liquid‐crystal displays (LCDs) is presented in which one linear polarization is preferentially coupled out by anisotropic scattering. The lightguide consists of a polymeric polarization‐dependent scattering film adhered to a transparent polymeric substrate. By changing the scattering power of the film, the polarized light outcoupling angles can be influenced and optimized to achieve a maximum outcoupling centered along the normal direction. The other linear polarization is mainly trapped in the lightguide and is shown to be recycled to enhance the overall light and/or energy efficiency. With a proper substrate choice, the achieved local contrast exceeds 14 over a 50‐mm range. A collimated light input further enhances the polarized contrast to well over 17.     

Direct excitation of xenon by ballistic electrons emitted from nanocrystalline‐silicon planar cathode and vacuum‐ultraviolet light emission

Abstract— To verify the possible use of energetic electrons for direct excitation of inert gas molecules, a nanocrystalline‐silicon (nc‐Si) planar ballistic emitter is operated in a high‐pressure xenon gas ambience. Under the pulse drive, vacuum‐ultraviolet (VUV) light emission is detected without any signs of discharge. The transient behavior of the VUV light emission properly corresponds to that of the nc‐Si emitter. In accordance with quantitative analyses of electron‐emission characteristics and the VUV output, the electron‐to‐photon conversion efficiency reaches 81% in the relatively efficient emitter case. The VUV output power is mainly determined from the number of electrons with energies compatible the with internal excitation of xenon. The emission spectrum observed at a pressure of 10 kPa shows peaks at 152 and 172 nm, which are thought to be originated from metastable Xe²* states. In contrast to the case of conventional impact ionization, no near‐infrared (NIR) peaks are seen in the spectrum. These results strongly suggest that the incidence of energetic electrons causes direct excitation of xenon molecules followed by radiative relaxation through intermediate states. The generated VUV light can be easily converted to visible light using a phosphor screen. As a discharge‐free VUV light emission, this phenomenon is potentially applicable to mercury‐free, high‐efficacy, and high‐stability flat‐panel light‐emitting device.