超高速水下航行器横滚控制研究

超高速水下航行器航行时由于被超空泡包裹着,使得其工况变得更为复杂,控制难度进一步加大;为了抑制或消除横滚,文章通过分析超高速水下航行器的运动特点,建立了航行器横滚运动模型方程,并进行特性分析和控制规律综合设计,最后提出使用配置控制面的方法来实现它的横滚控制;此方法的使用既为系统提供控制力又解决了系统弱阻尼的问题,同时还提高了系统的响应速度;最后运用PD算法,分析它的动态特性和幅频特性,仿真结果表明此方案简单,容易实现,且鲁棒性好,满足系统的要求。     

基于图像检测的发动机缸体探伤系统设计及应用

为了实现某型号航空发动机缸体的自动化检测,设计了一套全自动荧光磁粉探伤系统。介绍了系统的结构和实现方式、重点介绍了图像采集和图像处理部分,系统采用Laplacian算子对原始图像进行锐化处理,然后采用Prewitt算子进行边缘提取,最后采用面积和周长两个物理量作为判断产品合格与否的特征值;实际测量显示,系统的测量精度可达0.01 mm,满足发动机缸体检测的要求。     

最小化调整时间策略在PCB组装生产中的应用

研究和分析了少量多样生产环境下的PCB组装生产效率优化问题,并针对该问题建立了基于最小化调整时间策略的数学模型;优化问题的目标是确定批量生产时不同类型PCB板的最佳组装顺序以最小化调整时间,可近似描述为一个非对称旅行商问题(ATSP);提出了基于最近邻算法和2-opt算法的混合启发式算法求解该问题:先采用最近邻算法快速产生初始解,再用2-opt算法对初始解进行改良,最终得到问题的近似最优解;仿真数据表明,该算法具有优化效果好、性能稳定的优点。     

基于总线技术的网络智能传感器研究

针对当前工业领域中传感器小型化、智能化和网络化的发展趋势,在分析网络化智能传感器特点的基础上,开发了一种基于CAN总线的网络化智能传感器节点,详细论述了系统的硬件和软件设计,其中软件分别介绍了总线通讯模块和温度补偿模块。最后,通过三个传感器节点试验验证,该网络化智能传感器测量精度明显提高,克服了传统传感器在精确测量、数字化和组网等方面的不足,可以在工业领域推广和应用。其研究方法和技术还可推广到其它传感器应用系统中。     

超高速水下航行器航向控制研究

超高速水下航行器在水下航行时,表面大部分被超空泡所包覆,其运动特性发生显著变化,使得其工况变得更为复杂、控制难度加大;通过分析它的运动特点,建立了系统模型方程,并提出把空化器作为控制面,通过操纵其舵角改变量来控制航行器航向;最后运用PI极限舵控制算法进行仿真分析,结果表明此控制方法简单易实现,产生的偏差小,同时还提高了系统的响应速度,较好地满足了系统要求,分析结论可为超高速水下航行器控制系统设计提供参考。     

Memetic Algorithm With Extended Neighborhood Search for Capacitated Arc Routing Problems

The capacitated arc routing problem (CARP) has attracted much attention during the last few years due to its wide applications in real life. Since CARP is NP-hard and exact methods are only applicable to small instances, heuristic and metaheuristic methods are widely adopted when solving CARP. In this paper, we propose a memetic algorithm, namely memetic algorithm with extended neighborhood search (MAENS), for CARP. MAENS is distinct from existing approaches in the utilization of a novel local search operator, namely Merge-Split (MS). The MS operator is capable of searching using large step sizes, and thus has the potential to search the solution space more efficiently and is less likely to be trapped in local optima. Experimental results show that MAENS is superior to a number of state-of-the-art algorithms, and the advanced performance of MAENS is mainly due to the MS operator. The application of the MS operator is not limited to MAENS. It can be easily generalized to other approaches.     

Analysis of kinematics/statics and workspace of a 2(SP+SPR+SPU) serial–parallel manipulator

The kinematics/statics and workspace of a 2(SP+SPR+SPU) serial–parallel manipulator are studied systematically. First, a 2(SP+SPR+SPU) manipulator including an upper and a lower SP+SPR+SPU parallel manipulators is constructed, and the inverse/forward displacements, velocity, acceleration and statics of the lower/upper parallel manipulators are studied, respectively. Second, the kinematics and statics of the lower/upper manipulators are combined and the displacement, velocity, acceleration, statics, and workspace of a 2(SP+SPR+SPU) manipulator are analyzed systematically. Third, the analytic solutions’ examples are given and verified by the simulation mechanism. This manipulator has some potential applications for the robot’s arm, leg, and twist, the serial–parallel machine tools, the sensor, the surgical manipulator, the tunnel borer, the barbette of warship, and the satellite surveillance platform.     

Design and analysis of a self-tuning feedback controller for the Internet

Active queue management (AQM) is an effective method used in Internet routers for congestion avoidance, and to achieve a tradeoff between link utilization and delay. The de facto standard, the random early detection (RED) AQM scheme, and most of its variants use average queue length as a congestion indicator to trigger packet dropping. This paper proposes a novel packet dropping scheme, called self-tuning proportional and integral RED (SPI-RED), as an extension of RED. SPI-RED is based on a self-tuning proportional and Integral feedback controller, which considers not only the average queue length at the current time point, but also the past queue lengths during a round-trip time to smooth the impact caused by short-lived traffic dynamics. Furthermore, we give theoretical analysis of the system stability and give guidelines for selection of feedback gains for the TCP/RED system to stabilize the average queue length at a desirable level. The proposed method can also be applied to the other variants of RED. Extensive simulations have been conducted with ns2. The simulation results have demonstrated that the proposed SPI-RED algorithm outperforms the existing AQM schemes in terms of drop probability and stability.     

Kinematic Modeling and Analysis of Skid-Steered Mobile Robots With Applications to Low-Cost Inertial-Measurement-Unit-Based Motion Estimation

Skid-steered mobile robots are widely used because of their simple mechanism and high reliability. Understanding the kinematics and dynamics of such a robotic platform is, however, challenging due to the complex wheel/ground interactions and kinematic constraints. In this paper, we develop a kinematic modeling scheme to analyze the skid-steered mobile robot. Based on the analysis of the kinematics of the skid-steered mobile robot, we reveal the underlying geometric and kinematic relationships between the wheel slips and locations of the instantaneous rotation centers. As an application example, we also present how to utilize the modeling and analysis for robot positioning and wheel slip estimation using only low-cost strapdown inertial measurement units. The robot positioning and wheel slip-estimation scheme is based on an extended Kalman filter (EKF) design that incorporates the kinematic constraints for accuracy enhancement. The performance of the EKF-based positioning and wheel slip-estimation scheme are also presented. The estimation methodology is tested and validated experimentally on a robotic test bed.     

A research on social network-based personalized semantic retrieval model

Personalized semantic retrieval extends the query process and optimizes query results by mapping user preference of information to ontology. It can fetch different results according to the same queries from different users. This paper proposes a personalized semantic retrieval model based on social network. It implements the organization, presentation, acquisition and maintenance of user preference data. Finally, it uses these personalization data in the process of information retrieval.