Inducing sustained oscillations in feedback-linearizable single-input nonlinear systems

The present paper concerns the induction of stable sustained oscillation in feedback-linearizable single-input affine nonlinear dynamical systems via continuous-time state feedback control. The proposed application-oriented control approach is based on the conception of a state feedback controller that ensures the tracking of a limit cycle characterized in terms of the feedback-linearized system. Boundedness and convergence of the closed-loop trajectories are established following the Lyapunov theoretical framework and applying LaSalle׳s stability principle. The proposed approach is demonstrated with computer-simulated control experiments, showing that it ensures the convergence of the state trajectories of the controlled system to a designed limit cycle and that the methodology can, in principle, be applied to any single input feedback linearizable system.     

Improved average consensus algorithm based distributed cost optimization for loading shedding of autonomous microgrids

This paper addresses a new distributed cost optimization (DCO) method for load shedding (LS) of an islanded microgrid considering cost. A two-layer improved average consensus algorithm (IACA) of multi-agent system (MAS) is proposed, and the consensus characteristic of which is analyzed in detail. With the global information discovered in the first layer of the IACA, the DCO of LS can be solved by using the synchronization processing of the IACA in the second layer. PSCAD/EMTDC-based simulation models are built to study the value settings of consensus constants and the performances of the proposed DCO method. Simulation results verified the convergence improvement of the IACA and the effectiveness of the proposed DCO.     

A precision CNC turn-mill machining center with gear hobbing capability

With ever increasing demand for small parts with complex shapes and high dimensional accuracy, many traditional machine tools have become ineffective for machining these miniature components. Typical examples include dental implants, parts used in mechanical watch movements, and parts used in medical endoscopes. This paper introduces our PC-controlled CNC turn-mill machining center. It has 5 axes, an automatic bar feeder, an automatic part collection tray, and a tool changer. It features a special control algorithm for the synchronization of its axes that produces not only higher accuracy but also makes the machine easier to use. In addition, a volumetric error compensation algorithm is implemented to improve accuracy. Based on experiments, the machining error is ±3 μm for turning, ±7 μm for milling and the maximum profile error is less than ±7.5 μm for gear hobbing.     

Distributed-observer-based cooperative control for synchronization of linear discrete-time multi-agent systems

This paper considers output synchronization of discrete-time multi-agent systems with directed communication topologies. The directed communication graph contains a spanning tree and the exosystem as its root. Distributed observer-based consensus protocols are proposed, based on the relative outputs of neighboring agents. A multi-step algorithm is presented to construct the observer-based protocols. In light of the discrete-time algebraic Riccati equation and internal model principle, synchronization problem is completed. At last, numerical simulation is provided to verify the effectiveness of the theoretical results.     

压力机齿轮齿条同步机构的设计方法

简要介绍了压力机常用的同步机构;在比较多种同步机构的基础上,着重介绍了齿轮齿条同步机构同步的工作原理,阐述了该类同步机构的常用机械结构设计方法和强度刚度校核理论,并给出一个同步机构设计实例。此方法有效解决了齿轮齿条同步机构的设计问题。     

基于ARM&FPGA的玻璃刻花机控制器的设计

在分析玻璃刻花工艺的基础上,研究了以嵌入式微处理器ARM和FPGA为核心架构的玻璃刻花机控制器硬件平台,以及以Linux和Xenomai构建的实时操作系统为软件框架的软件平台。针对玻璃刻花加工对同步控制、误差补偿和加工工艺的要求,研究了相关的功能模块,完成玻璃刻花机控制器的设计开发。     

一种新型OFDM前导符号频域结构设计及其接收算法

文章对OFDM广播系统中前导符号的频域结构进行了研究,提出了一种固定序列和信令序列奇偶交错排列的新结构,其中固定序列可用于整数倍频偏估计和信道估计,信令序列用于承载信令内容。基于该结构,给出了一个前导符号频域的具体方案与参数。还介绍了适用于该种结构的接收算法,并基于上述参数与算法进行了仿真试验。仿真结果表明,该种前导符号频域结构具有优异的检测与解码性能,能够适用于各类固定及移动场景。     

某型车载雷达天线同步举升系统仿真研究

雷达天线快速、稳定的架设和撤收是举升系统最基本的要求之一,为提高车载雷达机动性,对其举升系统的研究十分重要。通过对天线举升液压系统的分析,建立系统的数学模型,采用交叉耦合控制方式,利用AMESim和Simulink联合仿真技术对系统进行仿真研究,分析比较举升系统在有、无偏载情况下的同步特性。仿真结果表明:交叉耦合控制方式下该举升系统具有工作平稳、可靠性好以及同步精度高等优点。     

Distributed self-tuning consensus and synchronization

The problem of self-tuning of coupling parameters in multi-agent systems is considered. Agent dynamics are described by a discrete-time double integrator with unknown input gain. Each agent locally tunes the strength of interaction with neighboring agents by using a normalized gradient algorithm (NGA). The tuning algorithm minimizes the square of the error between an individual agent’s state (velocity) and the one step delayed average of its own state and the states of its neighbors. Assuming that the network graph is strongly connected, it is proved that the sequence of coupling parameters is convergent and all velocities converge toward the same constant value.     

Analysis of an EMST-based path for 3D meshes

For several 3D data applications such as data-hiding or compression, data ordering is a major problem. We need to know how to achieve the same 3D mesh path between the coding and decoding stages. Various algorithms have been proposed in recent years, but we focus on methods based on Euclidean Minimum Spanning Trees (EMST). In this paper, we analyse the sensitivity of the EMST structure to obtain a more robust synchronization. We present a new theoretical analysis and a way to visualize EMST robustness. Moreover, this analysis can be useful in 3D data-hiding in order to detect fragile area and to predict the 3D object robustness during transmission on a noisy channel.