Application specific integrated circuit solution for multi‐input multi‐output piecewise‐affine functions

This paper presents a fully digital architecture and its application specific integrated circuit implementation for computing multi‐input multi‐output (MIMO) piecewise‐affine (PWA) functions. The work considers both PWA functions defined over regular hyperrectangular and simplicial partitions of the input domains and also lattice PWA representations. The proposed architecture is able to implement PWA functions following different realization strategies, using a common structure with a minimized number of blocks, thus reducing power consumption and hardware resources. Experimental results obtained with application specific integrated circuit (ASIC) integrated in a 90‐nm complementary metal‐oxide semiconductor standard technology are provided. The proposed architecture is compared with other digital architectures in the state of the art habitually used to implement model predictive control applications. The proposal is superior in power consumption (saving up to 86%) and economy of hardware resources (saving up to 40% in comparison with a mere replication of the three representations) to other proposals described in literature, being ready to be used in applications where high‐performance and minimum unitary cost are required. Copyright © 2015 John Wiley & Sons, Ltd.     

A study of decoupling with skeleton matrix in two‐degree‐of‐freedom generalized minimum variance control

There are many multi‐input multi‐output (MIMO) systems in chemical plants, and they have multiple time delays of different length in each input and output pair. This paper explains a two‐degree‐of‐freedom (2DOF) control system based on generalized minimum variance control (GMVC) for MIMO systems. It can improve the tracking performance with respect to the reference signals and the response properties for the disturbance. The states between the sampling period can be expressed by using the modified z transform to take account of multiple time delays. Additionally, a tracking controller is designed to decouple the plant. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 176(1): 28–36, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21046     

Minimum switching control for adaptive tracking

The switching adaptive control method has been used for quite a few years to solve the adaptive stabilization and model reference adaptive control problems. However, a serious problem with the switching control method is that the number of ‘candidate’ controllers can potentially be very large, especially for multi‐input–multi‐output systems. In this paper, we consider a class of minimum‐phase multi‐input–multi‐output plants with some mild compactness assumptions. Given any polynomial reference input, we provide a switching control law which guarantees exponentially stability of the closed‐loop system with exponential tracking performance. The main contribution of the paper is that we give the minimum number of candidate controllers required for switching. In particular, the number is equal to 2 for single‐input–single‐output plants (one for each sign of the high‐frequency gain), and is equal to 2^m for m‐input–m‐output plants. That is, the number is independent of the degree and the relative degree of the plant. Copyright © 2006 John Wiley & Sons, Ltd.     

Blind MIMO equalization with optimum delay using independent component analysis

Blind space–time equalization of multiuser time‐dispersive digital communication channels consists of recovering the users' simultaneously transmitted data free from the interference caused by each other and the propagation effects, without using training sequences. In scenarios composed of mutually independent non‐Gaussian i.i.d. users' signals, independent component analysis (ICA) techniques based on higher‐order statistics can be employed to refine the performance of conventional linear detectors, as recently shown in a code division multiple access environment (Signal Process 2002; 82 :417–431). This paper extends these results to the more general multi‐input multi‐output (MIMO) channel model, with the minimum mean square error (MMSE) as conventional equalization criterion. The time diversity introduced by the wideband multipath channel enables a reduction of the computational complexity of the ICA post‐processing stage while further improving performance. In addition, the ICA‐based detector can be tuned to extract each user's signal at the delay which provides the best MMSE. Experiments in a variety of simulation conditions demonstrate the benefits of ICA‐assisted MIMO equalization. Copyright © 2004 John Wiley & Sons, Ltd.     

Adaptive neural dynamic surface control of MIMO stochastic nonlinear systems with unknown control directions

In this paper, an adaptive neural output‐feedback control approach is considered for a class of uncertain multi‐input and multi‐output (MIMO) stochastic nonlinear systems with unknown control directions. Neural networks (NNs) are applied to approximate unknown nonlinearities, and K‐filter observer is designed to estimate unavailable system's states. Due to utilization of Nussbaum gain function technique in the proposed approach, the singularity problem and requirement to prior knowledge about signs of high‐frequency gains are removed, simultaneously. Razumikhin functional method is employed to deal with unknown state time‐varying delays, so that the offered control approach is free of common assumptions on derivative of time‐varying delays. Also, an adaptive neural dynamic surface control is developed; hence, explosion of complexity in conventional backstepping method is eliminated, effectively. The boundedness of all the resulting closed‐loop signals is guaranteed in probability; meanwhile, convergence of the tracking errors to adjustable compact set in the sense of mean quartic value is also proved. Finally, simulation results are shown to verify and clarify efficiency of the offered approach. Copyright © 2016 John Wiley & Sons, Ltd.     

Experimentally verified point‐to‐point iterative learning control for highly coupled systems

Iterative learning control (ILC) is a well‐established approach for precision tracking control of systems, which perform a repeated tracking task defined over a fixed time interval. Despite a rich theoretical framework accompanied by a wide array of application studies, comparatively little attention has been paid to the case of multiple input, multiple output (MIMO) systems. Here, the presence of interacting dynamics often correlates with reduced performance. This article focuses on a general class of linear ILC algorithms and establishes links between interaction dynamics and reduced robustness to modeling uncertainty, and slower convergence. It then shows how these and other limitations can be addressed by relaxing the tracking requirement to include only a subset of time points along the time duration. This is the first analysis to show how so‐called ‘point‐to‐point’ ILC can address performance limitations associated with highly coupled systems. Theoretical observations are tested using a novel MIMO experimental test facility, which permits both exogenous disturbance injection and a variable level of coupling between input and output pairs. Results compare experimental observations with theoretical predictions over a wide range of interaction levels and with varying levels of injected noise. Copyright © 2014 John Wiley & Sons, Ltd.     

基-2 FFT在音频分析及输出系统中的应用

主要介绍了一种将FFT算法移植到单片机上运行,通过对数字音频信号进行分析处理,以实现音乐频谱实时显示和声音输出的系统。系统硬件部分主要由声音输入、单片机模数转换、由LED组成的点阵单元以及声音信号放大输出等电路组成。利用高性能STC12C5A60S2单片机内建的模数转换功能,先将输入的音频信号采样、量化转换为数字信号,再通过软件编程进行FFT运算。输出处理结果点亮LED点阵,完成频谱显示。LED的明暗由音乐的频率变化决定。通过LM386运放芯片及外围电路将输入的音频信号进行放大后,由喇叭或者外接音箱输出。该设计不但具有较高的实用价值和观赏性,而且硬件电路结构简洁,开发、制作成本低。     

A 300‐mA load CMOS low‐dropout regulator without an external capacitor for SoC and embedded applications

This study proposes a 300‐mA external capacitor‐free low‐dropout (LDO) regulator for system‐on‐chip and embedded applications. To achieve a full‐load range from 0 to 300 mA, a two‐scheme (a light‐load case and a heavy‐load case) operation LDO regulator with a novel control circuit is proposed. In the light‐load case (0–0.5 mA), only one P‐type metal–oxide–semiconductor input‐pair amplifier with a 10‐pF on‐chip capacitor is used to obtain a load current as low as 0. In the heavy‐load case (0.5 to 300 mA), both P‐type metal–oxide–semiconductor and N‐type metal–oxide–semiconductor differential input‐pair amplifiers with an assistant push‐pull stage are utilized to improve the stability of the LDO regulator and achieve a high slew rate and fast‐transient response. Measurements show an output voltage of 3.3 V and a full output load range from 0 to 300 mA. A line regulation of 1.66 mV/V and a load regulation of 0.0334 mV/mA are achieved. The measured power‐supply rejection ratio at 1 kHz is −65 dB, and the measured output noise is only 34 μV. The total active chip size is approximately 0.4 mm² with a standard 0.5 μm complementary metal–oxide–semiconductor process. Copyright © 2017 John Wiley & Sons, Ltd.     

Observer‐based adaptive neural control of uncertain MIMO nonlinear systems with unknown control direction

This paper investigates adaptive neural network output feedback control for a class of uncertain multi‐input multi‐output (MIMO) nonlinear systems with an unknown sign of control gain matrix. Because the system states are not required to be available for measurement, an observer is designed to estimate the system states. In order to deal with the unknown sign of control gain matrix, the Nussbaum‐type function is utilized. By using neural network, we approximated the unknown nonlinear functions and perfectly avoided the controller singularity problem. The stability of the closed‐loop system is analyzed by using Lyapunov method. Theoretical results are illustrated through a simulation example. Copyright © 2012 John Wiley & Sons, Ltd.     

VLSI implementation of a configurable IP Core for quantized discrete cosine and integer transforms

In this paper, a low‐complexity and highly integrated IP Core for image/video transformations is presented. It can perform quantized 8×8 DCT and quantized 8 × 8/4 × 4 H.264 integer transforms on the presented configurable architecture using integer shift–add arithmetic operations. The MPEG‐4/H.264 experimental and circuit simulation results show that the reconfigurable modules and the CORDIC‐Scaler can not only approximate the arbitrary scaling values for different video standards efficiently but also achieve very high throughput and retain good transformation quality compared with the default methods in terms of PSNR. Therefore, the proposed IP Core is very suitable for low‐complexity multi‐purpose Video Codecs in SoC designs. Copyright © 2011 John Wiley & Sons, Ltd.     

High‐throughput IDCT architecture for high‐efficiency video coding (HEVC)

This paper presents a hardware design capable of supporting high‐efficiency video coding inverse discrete cosine transform (IDCT) with a 32×32 transform unit size, using a single 1‐D IDCT core with transpose memory to reduce costs. The proposed 1‐D IDCT core employs 16 computation paths for high throughput and is implemented using distributed arithmetic to facilitate the sharing of hardware resources. The proposed 1‐D IDCT is capable of calculating 1‐D and 2‐D data simultaneously along 32 parallel paths. When implemented using Taiwan Semiconductor Manufacturing Company (TSMC) 40‐nm CMOS technology, the proposed 2‐D transform core provides throughput of 6.4 gigapixels/s with a gate count of 335 k. The results show that a superior hardware efficiency can be achieved in the proposed 32‐point IDCT core compared with the existing works. Copyright © 2017 John Wiley & Sons, Ltd.     

Design of a contention‐free parallel double‐flow MAP decoder

Parallel processing and double‐flow methods, which are used to increase the speed of turbo‐code decoding, cause memory contentions. Although memory contentions due to parallel processing can be resolved by adopting the quadratic polynomial permutation (QPP) interleaver, the double‐flow method still causes memory contentions because of its read/write sequences from both ends of the input packets. Thus, we propose a modified architecture to resolve memory contentions for the double‐flow method to fit the QPP interleaver. In our experiment, the proposed method has a shorter decoding time and smaller hardware size compared the conventional method. A bit‐accurate simulation was performed, and hardware implementation with field‐programmable gate arrays (FPGAs) led to a high throughput of 80 Mbps. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Order and parameter estimation of time‐varying system by subspace method

This paper proposes an identification algorithm for time‐varying systems. We apply subspace method for estimation, since it is known to be useful when the input–output (I/O) data are observed by multi‐input multi‐output (MIMO) systems. Among many proposed techniques of subspace methods, we use MOESP (MIMO Output‐Error State Space model identification) in this paper, which assures arithmetic stability by RQ factorization and singular value decomposition (SVD). Generally, subspace methods can be applied after I/O data collection, so that we introduce updated steps of matrices for PI‐MOESP, which uses past inputs for instrumental variables. We propose a recursive update algorithm of PI‐MOESP, including estimation step of the system order, and consider some parameters inherent to the algorithm, namely, initial number of data, estimation step of the order, and forgetting factor. A numerical example shows the usefulness of the proposed method. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 157(2): 57–64, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20169     

两电机调速系统神经网络广义逆在线调整控制

针对多输入多输出(MIMO)非线性强耦合的两电机变频调速系统,对系统数学模型进行广义逆存在性分析,推导出系统的广义逆数学表达式,进一步构造神经网络广义逆系统串联在两电机系统之前,组成基于广义逆的伪线性复合系统,实现MIMO系统的线性化与解耦。在神经网络逆系统离线训练的基础上提出在线训练的控制方法,在电机的运行过程中对网络进行在线训练,不断修正网络权值,使网络适应环境的变化,增强其鲁棒性,更精确地逼近其逆系统。实验证明在用PLC作为主控制器的控制过程中,神经网络不断进行自我调整,增强了神经网络的适应性,提高了系统的稳定性和鲁棒性。     

A single‐stage phase‐shifted full‐bridge AC/DC converter with variable frequency control

This letter presents a single‐stage soft‐switched full‐bridge AC/DC converter for low‐voltage/high‐current output applications. A phase‐shifted method with a variable frequency control is used to regulate the DC bus voltage and the output voltage of the single‐stage AC/DC converter. The proposed circuit topology and control scheme exhibit superior performances (i.e. high power factor, high‐efficiency, and ring‐free features). Correspondingly, a laboratory prototype, 500 W 5V/100A AC/DC converter, is implemented to verify the feasibility of the proposed design. Copyright © 2009 John Wiley & Sons, Ltd.     

Rapid prototyping of MIMO‐OFDM based on parity bit selected and permutation spreading

In this paper, a novel MIMO‐OFDM transmission scheme is developed to effectively enable multi‐access by joint code design across multiple antennas, subcarriers, OFDM frames, and users. It achieves better spectrum efficiency while improving bit error rate performance. The proposed scheme uses either parity bit selected or permutation techniques to assign spreading codes at the transmitter side. As a result, the detection at the receiver is greatly improved because of the fact that identifying the spreading code(s) directly yields the transmitted data symbols. The paper also investigates the field‐programmable gate array implementation of the proposed algorithms; optimization techniques are proposed to reduce area, power, and time. These techniques include a pipelined architecture for inverse FFT/FFT blocks, an efficient low complexity algorithm for despreading based on counters and comparators and an optimized architecture for complex matrix inversion using Gauss–Jordan elimination (GJ‐elimination). Finally, the fixed‐point optimized field‐programmable gate array architecture for MIMO‐OFDM transceiver is developed, where the maximum allowed performance loss because of quantization is defined, the tradeoffs between BER performance and area reduction are investigated. Copyright © 2015 John Wiley & Sons, Ltd.     

A novel hybrid fix‐LLL lattice reduction algorithm for MIMO detection system

Lenstra–Lenstra–Lovász (LLL) is an effective lattice reduction algorithm for multiple‐input multiple‐output (MIMO) systems, which was considered to achieve full diversity in the MIMO fading channel. In the LLL algorithm, size reduction is performed for pairs of consecutive basis vectors, and the concern of numerical stability is raised. However, the whole complexity of the LLL algorithm is of polynomial order, and its characteristics of the convergence perform poor in MIMO system. In this paper, a variant version, named the novel hybrid algorithm, which combines both fix measurement and round measurement, is proposed. By modifying the iteration criterion and choosing proper values of the parameters, the algorithm has a large probability to skip the size reduction and cause a faster convergence, It means in one algorithm iteration the LLL potential can be reduced as much as possible. Also, the performance bound derived by the proximity factor shows that the hybrid LLL has a minor performance loss compared to the LLL algorithm. As a direct consequence, in simulation results, the hybrid LLL algorithm can make a better compromise between the rate of convergence, complexity of the algorithm, and algorithmic performance. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Design of multi‐input multi‐output minimum‐phase state control system with decoupling and feedforward compensation

This paper discusses the design of decoupling control for a multi‐input multi‐output (MIMO) linear system. A new configuration of the prepositional tandem matrix is presented as a decoupling compensator, and minimum‐phase state control is applied to the resulting decoupled system. In general, non‐minimum‐phase characteristics often accompany decoupled systems. Feedforward compensation makes the non‐minimum‐phase effect of each decoupled scalar system change to the delay time. A numerical example is given for the MIMO linear system, which conventionally results in non‐minimum‐phase systems. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 176(2): 53–61, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21117     

Adaptive inverse control of unmodeled stable SISO and MIMO linear systems

Adaptive‐signal‐processing techniques have been employed with great success in such applications as: system identification, channel equalization, statistical prediction and noise/echo cancellation. From a mathematical point of view, there is little difference between these applications and the types of operations required by control systems to control a dynamical system. This paper presents an approach to control systems called adaptive inverse control in which adaptive‐signal‐processing techniques are used throughout. Adaptive inverse control comprises three simultaneous processes. The plant is automatically modeled using adaptive system identification techniques. The dynamic response of the system is adaptively controlled using the resulting model and methods related to channel equalization. Adaptive disturbance canceling is performed using methods similar to noise canceling. The method applies directly to stable single‐input single‐output (SISO) and multi‐input multi‐output (MIMO) plants, and does not require an a priori model of the system. If the plant is unstable, it must first be stabilized using conventional feedback. This implies that at least a rudimentary model need be made if the plant is unstable. Once the plant is stabilized, adaptive inverse control may be applied to the stabilized system. Copyright © 2002 John Wiley & Sons, Ltd.     

Study and implementation of a 15‐W driver for piezoelectric actuators

This paper studies and implements a 15‐W driver for piezoelectric actuators. The discussed driver is mainly composed of a flyback converter and a power operational amplifier (P‐OPA). The flyback converter produces a variable DC voltage to supply the P‐OPA, which outputs an amplified sinusoidal signal with a DC bias of 100 V to drive the piezoelectric actuator. The power losses can be reduced because the supply voltage of the P‐OPA varies with the peak of the input signal. The power conversion efficiency of the driver can thus be promoted up to more than 30%. From the experimental results, the implemented prototype possesses some advantageous features, such as a nearly constant output‐to‐input voltage gain, a high slew rate, a high input impedance, a low output impedance, and low output voltage ripples. Copyright © 2016 John Wiley & Sons, Ltd.