基于PowerPC的嵌入式系统设计

介绍了以Freescale公司的高性能嵌入式芯片MPC5200B为处理器的嵌入式系统的设计,设计了外部存储器、通信接口部分、显示控制部分等,并对其系统软件VxWorks的BSP进行了配置。MPC5200B集成有高性能的MPC603e内核和丰富的外设接口,提高了MPC5200B的处理能力,可为大多数视频处理算法提供足够的支持。最后对系统进行了验证,系统很好地满足了嵌入式视频信号处理系统的要求。     

32位双核汽车微控制器

汽车用32位MCU MPC5510采用了Power Architecture技术，其两个e200z内核的架构可以48～80MHz的频率运行，在提供高性能处理和灵活性的同时，仍可满足低功耗的需求。MPC5510系的e200内核具有16／32位可变长度编码（VLE）功能，可以减少代码量，提高代码密度，降低内存要求；可选的双核架构，     

信源的一种随机映射编码算法

本文提出了一个信源的随机映射编码算法，该结果表明：在理论上存在着一种非全搜索性的编码算法，该算法可以被用来简化通常的矢量量化系统所采用的全搜索编码算法。     

垂直泊车路径跟踪控制研究

自动泊车控制系统的好坏对泊车成功率具有重要影响,本文以垂直车位为研究对象,提出了一种基于模糊PID算法与模型预测控制算法(MPC)的自动泊车联合控制算法。首先建立了车辆运动学模型,设置了泊车碰撞约束,并在此基础上进行无碰撞路径规划;然后建立模糊PID算法并调节相应参数,控制车辆纵向速度恒定,继而建立MPC算法控制车辆的横向角度。最后使用Simulink搭建相应的控制算法模型并与Carsim进行联合仿真分析。仿真结果表明：本文提出的联合控制算法具有较高的控制精度,其中偏航角误差控制在0.057 m以内,横向偏差的绝对值控制在0.08 m以内,能够满足垂直泊车对车辆控制的要求。     

一种基于DCT域的分布式视频编码

在简单介绍空域Wyner-Ziv分布式视频编码的基础上,给出了一种编码复杂度较低的基于交换域分布式视频编码方法.仿真结果表明此算法的编码性能优于空域Wyner-Ziv编码算法.     

易于硬件实现的内嵌图像编码算法

EZBC算法综合利用了子带内和子带间系数的相关性．把零树／零块结构和基于上下文编码的优点有机结合在一起,获得了比SPHIT算法更好的压缩性能,比EBCOT更高的压缩效率。但是EZBC算法编码中的两个排序链表需要很大且非固定的存储空间,这使得EZBC算法的硬件实现非常困难。在EZBC算法的基础上提出了一种易于硬件实现、低存储量、高压缩性能的内嵌零块图像编码算法。该算法利用比特平面节点重要性状态表和上下文查找表来完成整个编码过程和形成上下文。实验结果表明,所提出的算法具有与EZBC算法基本相同的高压缩性能,但所需存储空间约为EZBC算法的四分之一,所以该算法更易于硬件实现。     

一种减小语音矢量编码码率的算法

2维PV编码算法是一种将线性预测编码、SOM神经网络2维矢量编码以及Huffman编码相结合的语音信号编码算法。为了在保证译码恢复的语音质量良好的前提下,进一步减小编码的压缩率,以减小语音信号的存储空间,提出一种增加2维PV编码中矢量量化维数的高维PV编码算法。并利用Matlab软件编程进行2维、4维和8维PV算法的语音信号编解码实验。实验结果表明,在保证译码恢复声音质量良好的条件下,增加2维PV编码算法的量化矢量维数,可以减小码率,其中8维PV编码算法的码率最小为5.94 Kb/s,小于采用ADPCM编码算法的波形编码标准G.721的码率32 Kb/s(波形编码的最小码率),甚至小于采用LD-CELP编码算法的混合编码G.728的码率16 Kb/s。文中提出的编码算法在语言压缩编码方面将具有较高的研究价值和很好的应用前景。     

一种适于硬件实现的算术编码算法

本文提出了一种改进的Q-coder算术编码算法。这种算法的主要特点包括：使用Q表进行概率估计;采用Witten等人提出的重整化方法;用移位加来代替原算法中的乘法。采用移位中加方法,可以在硬件花费较少的情况下显著提高算法的编码效率;重整化方法可以用解决硬件实现中的进行翻转问题,本文还对算法的编码效率提高情况作了定量分析,同时对Q解码器进行了逻辑综合,结果表明了算法硬件实现的复杂度。     

基于MPC860T的实时视频传输系统设计

提出并实现了一种基于MPC860T的实时视频传输系统,从系统的硬件架构和软件设计上讨论了系统的关键技术和实现步骤,详述了系统的硬件设计、软件平台组成,给出了系统平台运行过程分析。实验结果表明,本系统具有较好的稳定性和实用性,能够满足实时视频传输的需求。     

基于运动矢量插值的运动补偿算法

本文首先研究了相关性约束运动估值算法，然后提出了基于运动矢量插值的运动估值算法，实验表明新算法的预测性能明显一比传统块匹配运动估值算法（ＢＭＡ）好，而且预测图象的主观质量得到显著改善。     

Estimation of frequency-selective CDMA channels with large possible delay and Doppler spreads

The problem of estimating channels with a large number of unknown coefficients is considered. A matching pursuit (MP) followed by cancellation (MPC) algorithm is presented. The algorithm consists of two steps. In the first step, a basic MP algorithm that identifies the strongest channel taps and successively cancels them is used. The second step of the algorithm uses the already identified channel taps to estimate the channel coefficients more accurately. The algorithm has several benefits: low complexity, significantly improved performance over conventional least squares (LS) in sparse channels, and handling of time-varying channels including carrier offsets. Methods to successfully terminate the MP step of the algorithm are presented and are shown to perform well. The statistical behavior of MPC is studied. The MPC estimator is found to achieve a performance close to the Cramer-Rao lower bound. Further, MPC is found to outperform conventional LS in terms of bit error rate when low training overhead is used.     

Model predictive control of bidirectional isolated DC–DC converter for energy conversion system

Model predictive control (MPC) is a powerful and emerging control algorithm in the field of power converters and energy conversion systems. This paper proposes a model predictive algorithm to control the power flow between the high-voltage and low-voltage DC buses of a bidirectional isolated full-bridge DC–DC converter. The predictive control algorithm utilises the discrete nature of the power converters and predicts the future nature of the system, which are compared with the references to calculate the cost function. The switching state that minimises the cost function is selected for firing the converter in the next sampling time period. The proposed MPC bidirectional DC–DC converter is simulated with MATLAB/Simulink and further verified with a 2.5 kW experimental configuration. Both the simulation and experimental results confirm that the proposed MPC algorithm of the DC–DC converter reduces reactive power by avoiding the phase shift between primary and secondary sides of the high-frequency transformer and allow power transfer with unity power factor. Finally, an efficiency comparison is performed between the MPC and dual-phase-shift-based pulse-width modulation controlled DC–DC converter which ensures the effectiveness of the MPC controller.     

一类新型的MPC脉压码

本文提出了以长度Ｎ＝４的Ｐ４（或Ｐ３）码为核的多相互补码（简称ＭＰＣ码）。并对６４位ＭＰＣ码在存在多普勒频移，强杂波及低信噪比的条件下作了仿真研究，并与Ｐ４码作了对比。文末还给出了实现ＭＰＣ脉压码的方法。     

Robust Model Predictive Control for Piecewise Affine Systems

In this paper, we study a robust model predictive control (MPC) strategy for piecewise affine (PWA) systems with uncertainty that is described as a set of polytopic parameter-varying models in a polytope corresponding to each partition of the PWA systems. First, an infinite horizon MPC technique for guaranteeing robust stability is developed for uncertain PWA systems. According to the condition of the PWA system states, the sequence of piecewise linear feedback controller at each sampling time is derived on-line by solving a convex optimization problem involving linear matrix inequalities. The feasible PWA control law design can robustly stabilize the uncertain PWA systems. However, the on-line optimization problems may lead to a computational burden. Then we further propose an improved robust MPC algorithm. When the current state is outside of the region of PWA systems containing the origin, the proposed on-line robust MPC algorithm is utilized; once the current state enters the region with the origin, sequence attraction domains where the origin is included are constructed off-line one within another, and the explicit control laws corresponding to different attraction domains can drive the state to the origin. The two algorithms are illustrated with a numerical example. The simulation results show that both controller design methods can stabilize the PWA systems with polytopic uncertainty, and the improved algorithm can reduce the on-line computation cost.     

Two-Dimensional Metallic Photonic Crystal with Point Defect Analysis Using Modified Finite-Difference Frequency-Domain Method

We have derived a modified finite-difference frequency-domain (FDFD) algorithm for two-dimensional (2-D) metallic photonic crystal (MPC) analysis. Using this method, the numerical results for the transverse-electric (TE) and transverse-magnetic (TM) modes in square and triangular lattices are in excellent agreements with those from other method. Then the correspondence of the band gaps between a unit cell and a supercell is demonstrated. Furthermore, by comparing the field distributions of the defect modes in a point defected MPC and a point defected dielectric photonic crystal (DPC), it is found that the defect MPC has a higher degree of localization, which means that MPC is preponderant for resonator and waveguide applications in millimeter wave and sub-millimeter wave bands.      

Model Predictive Control for Linear Parameter Varying Systems Using Parameter Dependent Lyapunov Function

In this brief, we propose a method of synthesizing a model predictive control (MPC) law for linear parameter varying systems. The proposed method is derived by using the parameter dependent Lyapunov function. The proposed MPC algorithm is reduced to the linear matrix inequality problem. It is shown that the proposed control method achieves less conservative results as compared with the several existing methods. A numerical example is provided to illustrate effectiveness of the proposed method     

A novel AQM algorithm based on feedforward model predictive control

Developing feedforward model predictive controller as an active queue management (AQM) scheme is studied in this paper. MPC is an advanced control strategy for AQM. However, the conventional MPC is usually an implementable form of feedback MPC. In this paper, a feedforward and feedback optimal control law is presented. It is a clean, easily implementable, version of model predictive control that incorporates feedforward. Firstly, we use the nominal fluid model to design the feedforward control input so that the output tracks the given queue length with small error. Furthermore, in order to achieve robust performance and to reject the (unmeasured) disturbance, the feedback component is designed. In particular, a disturbance observer is incorporated into the prediction output in standard feedback MPC. This framework can significantly improve performance in the presence of measurement noise and certain types of model uncertainty. Finally, the simulation results show the effectiveness of FF‐AQM algorithm.     

基于预测控制方法的UAV视觉编队飞行控制律设计

传统的无人飞行器(UAV)视觉编队控制律考虑约束的能力不足,制约了其工程实际应用。针对不足,基于预测控制方法设计了一种能够显式考虑约束的视觉编队控制律,该控制律通过滚动求解有限时域优化问题得到跟随飞行器(follower)的控制输入。利用相对距离变化率和视线方位角变化率预测值与实测值的偏差信息,提出了领航飞行器(leader)加速度的在线估计算法。仿真结果表明,所设计的编队控制律能够控制follower飞行器快速跟随leader飞行器形成期望的编队,所提出的leader飞行器加速度估计方法可行,具有较小的估计误差。     

Robust model predictive current control strategy for three-phase voltage source PWM rectifiers

Traditional model predictive control (MPC) strategy is highly dependent on the model and has poor robustness. To solve the problems, this paper proposes a robust model predictive current control strategy based on a disturbance observer. According to the current predictive model of three-phase voltage source PWM rectifiers (VSR), voltage vectors were selected by minimizing current errors in a fixed time interval. The operating procedure of the MPC scheme and the cause of errors were analysed when errors existed in the model. A disturbance observer was employed to eliminate the disturbance generated by model parameters mismatch via feed-forward compensation, which strengthened the robustness of the control system. To solve the problem caused by filter delay in MPC control, an improved compensation algorithm for the observer was presented. Simulation and experimental results indicate that the proposed robust model predictive current control scheme presents a better dynamic response and has stronger robustness compared with the traditional MPC.