一种降压型开关电源芯片电路的研究与设计

设计了一款PWM控制模式降压式（buck）直流一直流转换器芯片。该芯片为电压反馈控制模式,内部补偿使得反馈控制有很好的线性和很快的负载响应而无需通过外部设计。芯片采用CMSC0．5μm BCD工艺实现。PSPICE仿真结果表明,输出电压只有大约50mY的纹波,静态电流为3mA左右。输出电压在低于0．5V时,芯片具有短路降频功能,工作频率由81KHz降到23KHz左右,输出负载由0．2A跳变到2A时具有很好的负载调整率,大约为0．2％,转换效率可以达到85％以上。     

磁悬浮系统的控制方法研究

对于电磁吸浮型磁浮列车,悬浮控制是其关键部分,由于该系统的非线性和不稳定性,需要通过主动控制使其稳定悬浮。建立了磁悬浮列车悬浮系统模型,针对模型的非线性问题,采用精确反馈线性化将悬浮系统的非线性模型线性化,然后用闭环增益成形算法设计出非线性鲁棒控制器。用MATLAB的Simulink对具有扰动的非线性模型进行仿真,仿真结果表明控制效果没有静差和超调,调节时间快。     

Dynamic output feedback control of a flexible air-breathing hypersonic vehicle via T–S fuzzy approach

By utilising Takagi–Sugeno (T–S) fuzzy set approach, this paper addresses the robust H_∞ dynamic output feedback control for the non-linear longitudinal model of flexible air-breathing hypersonic vehicles (FAHVs). The flight control of FAHVs is highly challenging due to the unique dynamic characteristics, and the intricate couplings between the engine and fight dynamics and external disturbance. Because of the dynamics’ enormous complexity, currently, only the longitudinal dynamics models of FAHVs have been used for controller design. In this work, T–S fuzzy modelling technique is utilised to approach the non-linear dynamics of FAHVs, then a fuzzy model is developed for the output tracking problem of FAHVs. The fuzzy model contains parameter uncertainties and disturbance, which can approach the non-linear dynamics of FAHVs more exactly. The flexible models of FAHVs are difficult to measure because of the complex dynamics and the strong couplings, thus a full-order dynamic output feedback controller is designed for the fuzzy model. A robust H_∞ controller is designed for the obtained closed-loop system. By utilising the Lyapunov functional approach, sufficient solvability conditions for such controllers are established in terms of linear matrix inequalities. Finally, the effectiveness of the proposed T–S fuzzy dynamic output feedback control method is demonstrated by numerical simulations.     

Feedback nonlinear discrete-time systems

In this paper, we design an adaptive iterative learning control method for a class of high-order nonlinear output feedback discrete-time systems with random initial conditions and iteration-varying desired trajectories. An n-step ahead predictor approach is employed to estimate future outputs. The discrete Nussbaum gain method is incorporated into the control design to deal with unknown control directions. The proposed control algorithm ensures that the tracking error converges to zero asymptotically along the iterative learning axis except for the beginning outputs affected by random initial conditions. A numerical simulation is carried out to demonstrate the efficacy of the presented control laws.     

Boundary feedback stabilization of the telegraph equation: Decay rates for vanishing damping term

We study a semilinear mildly damped wave equation that contains the telegraph equation as a special case. We consider Neumann velocity boundary feedback and prove the exponential stability of the closed loop system. We show that for vanishing damping term in the partial differential equation, the decay rate of the system approaches the rate for the system governed by the wave equation without damping term. In particular, this implies that arbitrarily large decay rates can occur if the velocity damping in the partial differential equation is sufficiently small.     

Development of soft sensor by incorporating the delayed infrequent and irregular measurements

Originated from challenging industrial applications, this paper addresses a soft sensor development problem for linear systems with two types of measurements. One is fast, regular and delay-free measurements. The other is infrequent, irregular measurements with time-varying delays. The approach to be taken is based on the Kalman filter and data fusion technique, avoiding running the full augmented state Kalman filter, and leading to a considerably lower implementation cost. Although it is suboptimal, the loss in performance is minor compared to the optimal filter. Two simulation examples demonstrate the advantages of the proposed approach. An industrial soft sensor application example is also used to demonstrate its practicality.     

移动平台三维花卉植物触摸反馈可视化模拟

虚拟现实领域中,人们对三维花卉植物可视化及交互感的需求越来越强烈,而触摸力度引起的植物受力形变过程又无法采用现有的植物运动形变方法进行模拟,因为现有方法造成了模拟失真,交互感差。根据植物整株交互需求或单一叶片受力情况,分析不同方式的运动反馈模拟方法,先判断受力情况,根据动力学原理模拟整株受力,根据触摸屏获取数据,结合叶脉骨架旋转模型算法计算出单一叶片因受力而发生的形变,不需手动输入参数,就能模拟不同力度触摸造成的叶片形变。本方法应用在移动平台后,真实感和帧速率情况良好,可视化和交互感大大提升,并可推广到同类结构的物体模拟。     

Modeling and control of Wiener-type processes

We develop a simple relay feedback method to identify Wiener-type nonlinear processes. It separates the identification problem of the nonlinear static function from that of the linear dynamic subsystem to simplify the identification procedure significantly. Owing to the separation, the unmeasurable output of the linear dynamic subsystem can be obtained in a straightforward manner. Then, determining the model structure of the nonlinear static function becomes very simple and the estimates are robust to additive output noises. We can identify the whole activated region of the nonlinear static function as well as the ultimate information of the linear dynamic subsystem from only one relay feedback test. More information on the linear dynamic subsystem can be estimated by well-established linear system identification methods from additional tests. We use a nonlinear control strategy to compensate the nonlinear dynamics of the Wiener process so that the design parameters can be determined by usual tuning rules developed for linear processes and a high control performance can be achievable as in linear processes.     

以用户反馈为基础的数据库关键字检索技术分析

在当前的信息社会环境中,各领域所集结的数据资源日趋丰富,因此,提升信息检索的效率与质量就显得较为重要。从实践来看,根据检索用户的反馈信息,凭借更先进的技术手段来重新调整数据库关键字的检索设置,从而提升数据检索的精准度。本文就从用户反馈的角度为切入点来分析数据库关键字检索技术及其应用状况,以期为该领域实践提供有益的借鉴。