Suboptimal control with incomplete state feedback

A simple method is presented to compute a suboptimal partial-state-feedback control law, based on a suitable approximation of the optimal complete-state-feedback case. A parameter is also available to stabilise the resulting closed-loop system.     

Capacity-achieving probability measure for conditionally Gaussian channels with bounded inputs

A conditionally Gaussian channel is a vector channel in which the channel output, given the channel input, has a Gaussian distribution with (well-behaved) input-dependent mean and covariance. We study the capacity-achieving probability measure for conditionally Gaussian channels subject to bounded-input constraints and average cost constraints. Many practical communication systems, including additive Gaussian noise channels, certain optical channels, fading channels, and interference channels fall within this framework. Subject to bounded-input constraint (and average cost constraints), we show that the channel capacity is achievable and we derive a necessary and sufficient condition for a probability measure to be capacity achieving. Under certain conditions, the capacity-achieving measure is proved to be discrete.     

A digital method of modeling two-input quadratic systems withgeneral random inputs

A digital method of estimating linear and quadratic transfer functions of a two-input/multiple-output quadratically nonlinear system with general (i.e., non-Gaussian as well as Gaussian) random inputs is described. The approach is based on a frequency domain second-order Volterra functional series representation for a two-input/multiple-output system. Practical applications where it is important to have the capability to model dual-input nonlinear systems include: ground vibration tests of aircraft where two random exciting forces are applied in order to inject sufficient energy into all modes of the system; and experimental studies of transition to turbulence in fluids and plasmas, where the two inputs consist of two different velocity components, and plasma density and potential fluctuations, respectively. The approach described is being utilized to investigate such applications     

Suboptimal control of plants with uncertain parameters

A two-level technique for optimal system design is proposed, in which trajectory sensitivity cost is included with state and control variable terms. The resulting optimal system would be less sensitive to plant-parameter variations than one designed without such a trajectory-sensitivity cost term.     

Real-time digital simulation for systems control

This paper discusses techniques employed in the discrete modeling of physical systems for digital simulation and control applications. Traditional numerical integration techniques provide accurate means of model making but prove too slow for real-time simulation of complex systems or systems with fast response. For rapid digital simulation, a simplified discrete approximation is sought for the linear integro-differential operators of a continuous system. This discrete operator, a digitized transfer function, yields difference equations hopefully permitting real-time approximation of continuous system performance on a digital computer. Determination of the discrete operator is the essential goal of each of the simulation schemes described herein, though differing initial assumptions and approximations alter the resulting forms. After a brief review of these approaches to simulation, techniques for improved approximations for linear system transforms and for discrete parameter optimization and identification are developed. The optimum discrete transfer function which minimizes the sum of error squared between a linear continuous system output and a linear discrete system output is obtained. By adjusting gain parameters in the discrete transfer function, the simulation result is shown to be improved for various inputs and system nonlinearities. Application of standard variational methods to optimize the desired parameters leads to a two-point nonlinear boundary-value problem which is resolved via the techniques of quasilinearization and differential approximation. The procedure for application of various simulation methods is summarized, and the effectiveness of the methods is shown by the simulation of a second-order, nonlinear system for various inputs and sample intervals.     

Analysis of nonlinear systems with multiple inputs

Analytical modeling of communication receivers to account for their nonlinear response to multiple input signals is discussed. The method is based on the application of the Wiener-Volterra analysis of nonlinear functionals. The derived analytical relations were embodied in a computer program which provides nonlinear transfer functions of large circuits specified by their parameters. This method was applied to the prediction of behavior of communication receivers in the presence of interference. Examples illustrate the method and demonstrate its validity in the small-signal region.     

非连续正交频分复用系统次优导频设计

在非连续正交频分复用系统中,为了改善信道估计的性能并尽可能地降低计算复杂度,基于最小化最小二乘信道估计均方误差(Mean Square Error,MSE)的准则提出了一种次优导频设计方法.该方法利用凸映射解决了导频位置优化设计的非凸问题,求得符合三次函数关系的非均匀分布次优导频位置,并推导导频位置已知条件下的最优导频功率分布.仿真结果表明：所提次优导频设计方法与现存导频设计方法相比,能够获得较好的信道估计MSE性能,且具有计算简单的优势.     

Suboptimal resource allocation with MMSE detector for grouped MC-CDMA systems

This article puts forward two novel user-grouping algorithms for grouped multi-carrier （MC）-code division multiple access （CDMA） systems. As is well known, the adaptive assignment for user-grouping plays an important role for link quality of multi-access transmissions. In the study, the capacity-maximizing problem of user-grouping is formulated. By using the Kuhn-Tucker condition, the optimal criterion is deduced and found to have a similar form with signal to noise plus interference （SINR）. However SINR includes the signal power that can only be determined after user-grouping. Therefore the optimal criterion will lead to an impractical application. To deal with it, the user＇s equivalent SINR for minimum mean square error （MMSE） detector is proposed and served as a suboptimal assignment criterion, based on which two kinds of user-grouping algorithms are proposed. In the algorithms, only partial channel information is needed at the base station, which saves a large part of the bandwidth occupied by feedback information. Computer simulations have evaluated an excellent performance of the proposed algorithms at both link quality and data rate. Meanwhile, the proposed algorithms have lower implementation complexity for practical reality.     

Stability of model-reference systems with random impulsive inputs

The stability of the gain-adjusting loop of a simple model-reference adaptive-control system is investigated. The input to system and model is a sequence of impulses of random magnitude. The resulting behaviour is determined by an infinite product, and from this a necessary and sufficient criterion for the stability of the adaptive-loop gain is deduced.     

Steady-state analysis of piecewise-linear systems with periodic inputs

A specific form of a recently proposed algorithm is derived for the rapid determination of the steady-state response of large classes of piecewise-linear systems subjected to periodic inputs. It can be directly incorporated at marginal cost into a computer-oriented state space approach for generating the time domain response of such systems. The algorithm has been successfully applied to several circuits.     

Solution of nonlinear time-variant systems with random inputs

The adjoint method of analysis and Booton's equivalent-gain technique for nonlinearities can be combined, using a successive-approximation method, to analyse nonlinear time-varying systems where the input is random. The solution is performed on an analogue computer. Logic control of the computer speeds the calculation.     

Observer-based digital control of sampled-data systems with input/output time delays

Using asynchronous initial sampling with different sampling rates in the input and output terminals, a novel observer-based digital control law for sampled-data systems is proposed, which can cope with the presence of time delays in input acquisition and output sampling.This work was supported by the National Science Council of the Republic of China under grant NSC 89-2213-E-269-002 and by the Far East College.     

Equivalence of single-stage and Nstage optimum digital control systems

The system considered is linear with a quadratic performance index. A condition is derived under which an Nstage optimal-control policy reduces to a single-stage policy, with a consequent reduction in the computational effort required for on-line control. The condition is that the number of state variables appearing in the performance index should not exceed the number of control inputs to the system.     

Multimodal behaviour of nonlinear systems with narrowband Gaussian inputs

A method for predicting multimodal behaviour in nonlinear systems with narrowband Gaussian inputs is described. The technique is applicable when the nonlinearity is a function of the input and its derivatives.     

Pole selection of feedforward compensators considering bounded control input of industrial mechatronic systems

A new pole selection method for feedforward compensators of mechatronic servo systems is presented in this paper. It is necessary to have the system poles located at desirable positions on the s-plane in order to realize better servoing performance. However, selection of new poles is not a straightforward problem and in most industrial mechatronic systems, it has been a mere cut-and-dry procedure. In this research, feedforward compensator poles are related to the control input, and a criterion was developed to determine the desirable poles that improve the control input within its limits. This method was developed for the second-order model and it was simulated and experiments were performed with the Performer MK3s articulated industrial robot manipulator. Some attractive results have been obtained with the new method.     

基于DSP的激光标记数字控制系统设计

为了设计激光标记数字振镜控制系统,采用数字信号处理器芯片作为数字控制板的主处理器,使用具有高传输速率和支持热插拔的通用串行总线进行上位机与数字控制板的通信;标记图形的数据处理算法由具有高速运算能力的数字信号处理器完成,复杂可编程逻辑器件芯片完成控制信号的时序控制和输出,使用传送差分信号的RS-485总线进行控制系统与数字振镜和激光器的通信,根据理论分析和参量模拟,得到了对数字振镜的转动角度和激光器功率的高精度控制。结果表明,该系统可以实现实时、高速、高精度的激光标记。     

Suboptimal dual adaptive control for blood pressure management

Presents a new approach for adaptive control of blood pressure using vasoactive drugs. The idea is to use an adaptive controller that incorporates the concept of duality in the sense of Feldbaum (1965) and to consider the cost functional M-steps ahead in time. The dual property means that the control signal is chosen in such a way that estimation of the model parameters and regulation of the output signals are optimally balanced. Extensive computer simulations for different values of M shows that the sample mean of the achieved cost tends asymptotically to a limiting value while the variance is reduced. The proposed suboptimal adaptive controller has also an improved transient response when compared to a certainty equivalent controller     

数字播控系统若干技术问题的探讨

宁波台于今年５月份对对全部４套自办节目的播出系统和总控系统完成了数字化建设和改造。播出系统采用ＧＶＧ公司生产的ＰｒｏｆｉｌｅＸＰ硬盘服务器和Ｍ２１００数字播出切换台,总控系统采用ＧＶＧ公司生产的ＳＭＳ７０００数字模拟兼容矩阵。几个月来,４套全数字播出系统及总控系统运行正常,系统指标符合国家规定的行业标准,工作稳定,使用方便、灵活,效价比较高。１采用全数字播出系统的几点考虑１．１符合国家广电总局“十五”规划的总体要求今年３月,经上级批准,宁波电视台与原宁波有线电视台合并。合并后的宁波电视台位于…     

A new model for repairable systems with bounded failure intensity

This paper proposes a new model, called the 2-parameter Engelhardt-Bain process (2-EBP) model, to describe the failure pattern of complex repairable systems subjected to reliability deterioration with the operating time, and showing a finite bound for the intensity function. The characteristics of the 2-EBP model are discussed, and the physical meaning of its parameters is derived. The 2-EBP model can be viewed as a dynamic power law process, whose shape parameter ranges from 2 to 1 as the system age increases, converging asymptotically to the homogeneous Poisson process. Maximum likelihood estimates of model parameters & other quantities of interest, as well as a testing procedure (based on the likelihood ratio statistic) for time trend, are provided. Numerical applications are given to illustrate the 2-EBP model & the related inferential procedures, and to emphasize on the caution to use in assuming the (very often used) power law process when the presence of a finite bound for the failure intensity is conjecturable.