Frequency-Spectrum-Based Antiwindup Compensator for PI-Controlled Systems

This paper presents a frequency-spectrum-based conditional-integration antiwindup strategy for a general proportional-integral-type controller. The on/off condition of integral action is determined by a frequency-domain analysis of the actuator-input command without prior knowledge of set-point changes. The dynamic performance of the proposed scheme assures a desired tracking-response curve with minimal oscillation and settling time even with a change of operating conditions. This algorithm is useful in many high-performance induction-machine applications, as it does not allow the oscillation and overshoot of speed/torque responses. The main idea can be extended to general applications such as those involving chemical processes and industrial robots     

Adaptive precision positioning of smart composite panels subjected to external disturbances

This paper addresses the simultaneous precision positioning and vibration suppression of smart composite panels with piezoelectric patches. The filtered-x least mean square (LMS) adaptive feedforward control (AFC) for vibration/noise reduction is extended for this purpose, and AFCs with feedback loops are developed. The introduced feedback loops enhance the computational efficiency of the adaptive LMS algorithm and vibration suppression capability. Besides the classic PID feedback loop, the internal model configuration is introduced as well for the case in which the external disturbance is unknown. Experiments are performed on an active composite panel under a harmonic or random disturbance. The effects of the convergence factors of the adaptive algorithm on the overshoot and settling time of the position response of the smart composite panel are investigated. The vibration suppression and precision positioning capabilities of the AFC and the AFC with feedback loops are compared and discussed. The experimental results demonstrate that the overall positioning and vibration suppression performances for the AFC with feedback loops are better than those for the AFC.     

Adaptive control of arterial blood pressure with a learningcontroller based on multilayer neural networks

The authors discuss a two-model multilayer neural network controller for adaptive control of mean arterial blood pressure (MABP) using sodium nitroprusside. A model with an autoregressive moving average (ARMA), representing the dynamics of the system, and a modified backpropagation training algorithm are used to design the control system to meet specified objectives of design (settling time and undershoot/overshoot) and clinical constraints. The controller is associated with a weighting-determinant unit (WDU) to determine and update the output weighting factor of the parallel two-model neural network for adequate control action and a control-signal modification unit (CMU) to comply with clinical constraints and to suppress the effect of adverse noise and to improve the WDU performance. Extensive computer simulations indicate satisfactory performance and robustness of the proposed controller in the presence of much noise, over the full range of plant parameters, uncertainties, and large variations of parameters     

基于量子粒子群算法的PID参数自整定方法

PID控制在工业生产中应用非常广泛.以直流电机模型为被控对象,提出了基于量子粒子群算法的PID参数自动整定方法.应用经典的Ziegler-Nichols方法整定PID参数,被控对象性超调大往往难以满足要求.粒子群算法是通过模拟鸟群觅食过程中的迁徙和群聚行为而提出的一种基于群体智能的全局随机搜索算法.将量子粒子群算法用于优化PID参数,并与Z-N法整定的PID控制器性能进行对比.仿真结果发现,与Z-N法相比,基于粒子群算法优化的PID控制器,系统超调明显减小.除QPSO-PID(ITSE)对应的系统具有较长调节时间外,虽然应用不同优化目标优化后的PID参数不同,控制对象的响应性能却非常相似.     

扰动分离自抗扰控制在光电稳定平台上的应用

针对当前光电稳定平台伺服系统中扰动抑制能力不足的问题,提出一种扰动分离自抗扰控制（DSADRC）算法。扰动分离自抗扰控制充分利用工程实际中可获取到的部分已知的光电稳定平台模型信息及经典控制中的控制器信息,并将其加入到自抗扰控制的设计中。该算法通过减少光电稳定平台系统中的总扰动量,增加系统的扰动观测精度及扰动抑制能力。同时,通过算法设计实现了经典控制器的复用,减少了设计工作量。仿真实验结果表明:在控制器相同、扰动条件相同的情况下,扰动分离自抗扰控制阶跃响应调节时间减少58.8%,上升时间减少26.5%,且无超调量;在1V2Hz等效扰动下,系统稳态精度提高51.5%,系统性能提升效果明显。在实物验证实验中,对于不同频率的等效扰动,相比PID控制,扰动分离自抗扰控制稳态精度提升50%以上,有效地提高了光电稳定平台的稳态精度。     

Adaptive high bandwidth current control for induction machines

For high performance induction machine control, the technique of indirect rotor flux oriented vector control is commonly utilized. The torque performance of this technique is significantly affected by the performance of the current control loops. In this paper a new adaptive high bandwidth current controller for induction machines is presented. The technique is derived and validated through simulation and experimental results. The new architecture is shown to achieve a dead-beat response, with a rise time of one sample period and no overshoot, when the inverter voltage limit is not exceeded. When the voltage limit is exceeded the current response is achieved in a minimum time with no overshoot. It is shown that the new control technique achieves similar dynamic response to the conventional dead-beat control scheme while eliminating parameter sensitivity issues. It is demonstrated that the new algorithm offers higher bandwidth than the commonly used synchronous frame proportional plus integral control technique while maintaining good steady state performance.     

Hybrid Companding Delta Modulation with Variable-Rate Sampling

Hybrid companding delta modulation (HCDM) is known to be superior in performance to other instantaneous or syllabic companding delta modulation systems [1]. To improve its performance or to reduce the bit rate further in coding speech, we propose to use a variable-rate sampling scheme in the HCDM system. The proposed system employs several different sampling rates but transmits the output binary signal at a fixed rate using a buffer. By using the variable-rate scheme, one can improve its performance by 3 to 4 dB in signal-to-quantization noise ratio (SQNR) over the fixedrate HCDM. Detailed algorithm and computer simulation results are presented. Buffer behavior and its control are also discussed. In addition, it is shown that the performance gain of a DM system with variable-rate sampling depends on the degree of variation of the input signal.     

多用户分集与能量受限非可信中继系统遍历安全性能分析

研究了一种能量受限的非可信中继与多用户分集技术相结合的两跳链路安全网络通信模型。为提升系统安全性能，本文采用混合时间-功率分配中继(time-power splitting-based relaying, TPSR)协议,并结合机会调度策略(opportunistic scheduling strategy, OSS)从多用户分集网络中选择一个最佳目的节点作为信息接收端。基于随机选择(random selection, RS)策略，该文中利用低复杂度的高斯Q函数分析系统的安全性能以及在协作中继上进行能量采集活动不中断的条件下推导了系统的遍历安全速率(ergodic secrecy rate, ESR)的近似闭合表达式。此外，将提出的OSS与RS通信方案下性能进行对比，证明本文所提出的OSS更适用于分布式多用户选择网络。      

基于蚁群算法的无刷直流电机PID控制器测试系统

本文采用了一种基于蚁群算法的无刷直流电机PID控制器参数优化策略,给出了该算法的具体实现步骤。仿真与实验表明:相对于遗传算法和模拟退火算法,该方法在改进阶跃波响应性能方面,如减少稳态误差、无刷直流电机的速度控制中的上升时间、调整时间以及其最大超调量等方面,其效率更高     

基于多约束NSGA2算法的空管监视台站优化选址

为了实现空管监视台站的科学规划、合理布局,探讨了一种高效通用的优化选址算法。通过深入分析监视台站优化选址的问题,建立了多变量组合寻优的组网模型,提出了选址的简要约束条件和3个覆盖性能评估的目标函数,并在此基础上设计了空管监视台站优化选址的多约束NSGA2算法,该算法考虑了监视台站选址的各类影响因素加入多约束条件判定模块和种群修正模块。真实场景的仿真实例表明,优化输出的最优部署方案具有良好的覆盖性能,航路二重覆盖能达到98%以上,终端区域三重覆盖能达到95%以上。     

Nonlinear techniques for the joint estimation of cochannel signals

Cochannel interference occurs when two or more signals overlap in frequency and are present concurrently. Unlike in spread-spectrum multiple-access systems where the different users necessarily share the same channel, cochannel interference is a severe hindrance to frequency- and time-division multiple-access communications, and is typically minimized by interference rejection/suppression techniques. Rather than using interference suppression, we are interested in the joint estimation of the information-bearing narrow-band cochannel signals. Novel joint estimators are proposed that employ a single-input demodulator with oversampling to compensate for timing uncertainties. Assuming finite impulse-response channel characteristics, maximum likelihood (ML) and maximum a posteriori (MAP) criteria are used to derive cochannel detectors of varying complexities and degrees of performance. In particular, a (suboptimal) two-stage joint MAP symbol detector (JMAPSD) is introduced that has a lower complexity than the single-stage estimators while accruing only a marginal loss in error-rate performance at high signal-to-interference ratios. Assuming only reliable estimates of the primary and secondary signal powers, a blind adaptive JMAPSD algorithm for a priori unknown channels is also derived. The performance of these nonlinear joint estimation algorithms is studied through example computer simulations for two cochannel sources     

A New ML Based Interference Cancellation Technique for Layered Space-Time Codes

This paper presents a new and simple decoding algorithm for layered space time block codes such as the two independent Alamouti's codes which are also called the double space-time transmit diversity (DSTTD) system. By using group interference suppression and successive interference cancellation, we can treat DSTTD as two independent space-time block codes (STBC). We can then decode both of these STBC's through a simple maximum likelihood (ML) detector with null space-based interference cancellation. We also compare the proposed interference cancellation (IC) scheme with the conventional MMSE IC scheme. The performance of the proposed IC scheme is comparable to that of the MMSE IC scheme while the complexity reduction factor of the proposed scheme can be up to 5 compared to the MMSE IC scheme.     

基于粒子群优化的网络拥塞控制新算法

PI控制器常用于主动队列管理中,但参数整定上的试凑法具有盲目性,算法的瞬态性能也不够理想.本文推导了基于流体流理论的网络简化模型,基于该模型将集群智能中的改进粒子群优化算法(PSO)应用于PID控制器参数优化,定义了一个综合调节时间、上升时间、超调量、系统静态误差、正弦跟踪误差等动静态性能指标函数,在给定的参数空间进行组合优化搜索,迅速求得获取使性能指标优化函数极小化的一组PID控制器参数,将PID控制器应用于网络主动队列管理系统中.仿真结果表明,在大时滞和突发业务流的冲击两种情况下,该方法设计的控制器的动静态性能优于RED、PI算法,超调量均小于5%,调节时间分别小于5秒、4秒,稳态误差分别小于两个数据包和3个数据包.     

Nonlinear Tracking Control for a Hard Disk Drive Dual-Stage Actuator System

This paper presents a nonlinear tracking control method for a hard disk drive dual-stage actuator (DSA) system that consists of a voice coil motor (VCM) actuator and a piezoelectric (PZT) microactuator. Conventional track seeking controllers for DSA systems were generally designed to enable the VCM actuator to approach the target track without overshoot. However, we observe that this strategy is unable to achieve the minimal settling time when the target tracks are beyond the PZT actuator stroke limit. To further reduce the settling time, we design the VCM actuator controller to yield a closed-loop system with a small damping ratio for a fast rise time and certain allowable overshoot. Then, a composite nonlinear control law is designed for the PZT actuator to reduce the overshoot caused by the VCM actuator as the system output approaches the target track. Experimental results show that the proposed dual-stage servo outperforms the conventional dual-stage servo in short-span seeking and, additionally, achieves better track following accuracy than the VCM only single-stage servo.     

A DSP-based implementation of a new nonlinear control for a three-phase neutral point clamped boost rectifier prototype

This work presents the design and implementation of a nonlinear control strategy for a three-phase three-level neutral-point-clamped boost rectifier. The adopted control consists of nonlinear feedback linearization technique. The nonlinear state-space model of the rectifier was obtained in the dq0 reference frame. The input/output feedback linearization is then applied and the linearizing control law is derived. Therefore, the resulting model is linearized and decoupled in three independent subsystems. Afterwards, the stabilizing controllers are designed based on linear techniques to control line currents, output, and neutral point voltages. The control law is designed using Simulink/Matlab and applied to the converter via a 1.8-kHz pulsewidth modulator (PWM). Both control law and PWM signals are executed in real time using the DS1104 DSP of dSPACE. A 1.2 kW laboratory prototype is built for validation purposes. The proposed control law robustness is validated for diverse severe load and system parameter variations. It shows robust performance in terms of high power factor, low total harmonic distortion and output voltage ripples, small overshoot, and short settling time.     

Predictive ordering technique and feedback transform coding fordata compression of still pictures

A picture data compression method consisting of a hybrid cascade having four processing stages is presented. The processing stages are: predictive ordering technique (POT), feedback transform coding (FTC), vertical subtraction of quantized coefficients (VSQC), and predictive coding refinements in the signal space consisting of either overshoot suppression (OS) as a first variant or hybrid block truncation coding (HBTC) as a second one. Each of these stages is described, and reconstructed pictures are presented with their coding fidelity performances (mean square quantization error, mean absolute error and signal-to-noise ratio), using as test pictures a portrait and a LANDSAT image. It is shown that good quality images at low bit rates (0.55 to 1.1 bits/pixel) have been obtained     

Relationship between settling time and pole–zero placements for three-stage CMOS opamp

In this article, the effect of pole–zero placements on settling time has been analysed for a three-stage CMOS operational amplifier (opamp) with nested Miller compensation (NMC) and reversed nested Miller compensation (RNMC) schemes. In this study, optimised balancing of speed and power is done for a three-stage CMOS opamp for a given load condition (on-chip opamp). Optimum values of circuit parameters have been derived for power efficient shifting of poles and zeros. The effect of placement of poles and zeros on dynamic settling error (DSE) is analysed by means of numerical simulation using MATLAB. This analysis will be useful to ascertain the relationship between pole–zero placements and settling time. The study of the effects of compensation elements on pole–zero placements has been done to assist the circuit designers to achieve better performance. Analysis of the effect of capacitive load on pole–zero placements and DSE has been done in this study. A technique has been developed to find out the upper and lower limits of compensation capacitor that allows fast settling with low power. The validity of the analytical work has been checked by simulation using Tanner tool in 0.35-µm CMOS technology. In the case of RNMC scheme, a power dissipation of 60.17?µw and a settling time of 340?ns are achieved; the results obtained are better than the earlier reported design technique. In the case of NMC, the simulation has been done to validate the analytical analysis.     

Image dehazing using morphological opening,dilation and Gaussian filtering

Image pre-processing is a critical stage in computer vision systems, with greater relevance when the input images are captured in outdoor environments because the pictures could contain low contrast and modified colors. A common condition present in outdoor images is haze. In this work, a new dehazing algorithm based on dark channel prior mathematical morphology operations (opening and dilation), and a Gaussian filter, is proposed. Moreover, the proposed algorithm performance is compared qualitatively and quantitatively against previously reported algorithms. Obtained results show that the proposed algorithm requires less processing time providing higher quality dehazing results than other state-of-the-art approaches.     

Adaptive hybrid clock discipline algorithm for the network timeprotocol

This paper describes the analysis, implementation, and performance of a new algorithm engineered to discipline a computer clock to a source of standard time, such as a GPS receiver or another computer synchronized to such a source. The algorithm is intended for the network time protocol (NTP), which is in widespread use to synchronize computer clocks in the global Internet, or with another functionally equivalent protocol such as DTSS or PCS. It controls the computer clock time and frequency using an adaptive-parameter hybrid phase/frequency lock feedback loop. Compared with the current NTP Version 3 algorithm, the new algorithm developed for NTP Version 4 provides improved accuracy and reduced network overhead, especially when per-packet or per-call charges are involved. The algorithm has been implemented in a special-purpose NTP simulator, which also includes the entire suite of NTP algorithms. The performance has been verified using this simulator and both synthetic data and real data from Internet time servers in Europe, Asia, and the Americas     

基于高摆率误差放大器的无片外电容LDO设计

为了解决无片外电容低压差线性稳压器(LDO)的瞬态响应性能较差的问题,采用跨导提高技术设计了一种高摆率的误差放大器.在误差放大器的基础上,通过电容将LDO的输出端耦合至电流镜构建瞬态增强电路,提升LDO的瞬态响应能力,且瞬态增强电路可以引入两个左半平面零点,改善环路的稳定性.同时,误差放大器采用动态偏置结构,进一步减小...