A Lyapunov‐based small‐gain approach on design of triggering conditions in event‐triggered control systems

This paper studies a Lyapunov‐based small‐gain approach on design of triggering conditions in event‐triggered control systems. The event‐triggered control closed‐loop system is formulated as a hybrid system model. Firstly, by viewing the event‐triggered control closed‐loop system as a feedback connection of two smaller hybrid subsystems, the Lyapunov‐based small‐gain theorems for hybrid systems are applied to design triggering conditions. Then, a new class of triggering condition, the safe, adjustable‐type triggering condition, is proposed to tune the parameters of triggering conditions by practical regulations. This is conducive to break the restriction of the conservation of theoretical results and improve the practicability of event‐triggered control strategy. Finally, a numerical example is given to illustrate the efficiency and the feasibility of the proposed results. Copyright © 2015 John Wiley & Sons, Ltd.     

High‐precision formation control of nonlinear multi‐agent systems with switching topologies: A learning approach

Arbitrary high precision is considered one of the most desirable control objectives in the relative formation for many networked industrial applications, such as flying spacecrafts and mobile robots. The main purpose of this paper is to present design guidelines of applying the iterative schemes to develop distributed formation algorithms in order to achieve this control objective. If certain conditions are met, then the control input signals can be learned by the developed algorithms to accomplish the desired formations with arbitrary high precision. The systems under consideration are a class of multi‐agent systems under directed networks with switching topologies. The agents have discrete‐time affine nonlinear dynamics, but their state functions do not need to be identical. It is shown that the learning processes resulting from the relative output formation of multi‐agent systems can converge exponentially fast with the increase of the iteration number. In particular, this work induces a distributed algorithm that can simultaneously achieve the desired relative output formation between agents and regulate the movement of multi‐agent formations as desired along the time axis. The illustrative numerical simulations are finally performed to demonstrate the effectiveness and performance of the proposed distributed formation algorithms. Copyright © 2014 John Wiley & Sons, Ltd.     

Morphological image fusion using the extracted image regions and details based on multi-scale top-hat transform and toggle contrast operator

Remaining useful information of the original images in the fusion image is very important in image fusion. To be effective for image fusion, a multi-scale top-hat transform and toggle contrast operator based algorithm using the extracted image regions and details is proposed in this paper. Top-hat transform could extract image regions, and operations constructed from toggle contrast operator could extract image details. Moreover, multi-scale top-hat transform and toggle contrast operator could be used to extract the effective image regions and details at multi-scales of the original images. Then, the extracted image regions and details are imported into the final fusion image to form the effective fusion result. Thus, the proposed multi-scale top-hat transform and toggle contrast operator based algorithm is an effective image fusion algorithm to keep more useful image information. The combination of the top-hat transform and toggle contrast operator for effective image fusion is the main contribution of this paper, which is the extension of the previous work using only the toggle contrast operator for edge preserved image fusion. Experimental results on multi-modal and multi-focus images show that the proposed algorithm performs very well for image fusion.     

公路施工压力试验机网络监测系统设计与实现

针对目前公路施工领域力学试验过程中数据可靠性低、不便于监测的缺点,设计了压力试验机网络监测系统;在论述了系统的总体结构的基础上,完成了试验数据采集与网络传输系统的软硬件设计、样品条形码信息管理系统设计,以及试验数据与信息查询系统设计;基于文章方法设计的网络监测系统已经在云南某高速公路工地试验室得到应用,实际运行情况表明,系统工作高效稳定,实现了对工地试验室试验过程的远程监督和管理,以及对样品的过程跟踪,可以有效保证工程项目的施工质量。     

变精度粗糙集模型及其应用研究

介绍了广义粗糙集模型和Ziarko变精度粗糙集模型,找出了它们的不足;借助引入的误差参数β(0≤β<0.5),给出了基于后继邻域的一般二元关系下变精度粗糙集模型的β上近似、β下近似、3边界和β负域的定义以及β近似质量和β粗糙性测度定义;详细讨论了β上、下近似算子的性质、该模型与其他粗糙集模型的关系以及一般二元关系下两种变精度粗糙集模型的关系;最后,举例说明了该模型在信息处理中的应用。     

Design and realization of hybrid ACO-based PID and LuGre friction compensation controller for three degree-of-freedom high precision flight simulator

Three degree-of-freedom (3-DOF) high precision flight simulator is a type of key hardware-in-loop equipment in the fields of aeronautics and astronautics. The conventional Proportional–Integral–Derivative (PID) is a widely used industrial controller that uses a combination of proportional, integral and derivative action on the control error to form the output of the controller. It is well known that the undesired phenomena caused by friction can lead to overall flight simulator performance degradation or instability. This paper presents a novel kind of hybrid Ant Colony Optimization (ACO)-based PID and LuGre friction compensation controller for 3-DOF high precision flight simulator. On the basis of introduction of the basic principles of ACO, the controlling scheme design for the 3-DOF high precision flight simulator is presented. Based on the popular LuGre friction model, a novel nonlinear friction compensation controller for 3-DOF high precision flight simulator is also developed. The proposed Lyapunov function proves the robust global convergence of the tracking error. The parameters tuning of PID can be summed up as the typical continual spatial optimization problem, grid-based searching strategy is adopted in the improved ACO algorithm, and self-adaptive control strategy for the pheromone decay parameter is also adopted. Modularization design is adopted in the 3-DOF high precision flight simulator. This software can process the position and status signals, and display them on the friendly interface. Double buffer mechanism is adopted in the communication protocol between lower Industrial Personal Computer (IPC) and upper IPC. The series experimental results have verified the feasibility and effectiveness of the proposed hybrid ACO-based PID and LuGre friction compensation controller.     

A stick-slip piezoelectric actuator with an integrated sensing unit for the measurement and active control of the contact force

Output characteristics of the stick-slip piezoelectric actuators are intrinsically affected by the contact force between the driving foot and the mover. Therefore, it would be quite meaningful to measure and control the contact force. In this study, by integrating a group of strain gauges into the driving compliant mechanism, a stick-slip piezoelectric actuator with measured contact force was proposed. The main structural parameters of the driving compliant mechanism were designed and analyzed. Through experiments, the sensing unit was calibrated, and the results showed that it had good linearity, and the noise level was 3.5 mN. The contact force was measured by the sensing unit, and accordingly, the relationship between the contact force and the stepping characteristic was explored. It was shown that the change in contact force would lead to the evolution in stepping characteristic, which finally resulted in the motion nonlinearity of the actuator in large stroke output. Accordingly, by actively controlling the contact force, a method was proposed to tune the stepping characteristic. The comparative results demonstrated that this method could significantly improve the motion linearity of the actuator in large stroke output under various preloads and even very rough surface.     

Parameter identification and position control for helical hydraulic rotary actuators based on particle swarm optimization

It is difficult to obtain an accurate mathematical model in electro-hydraulic servo control system, due to the nonlinear factors such as dead zone, saturation, flow coefficient, and friction. Hence, a parameter identification algorithm, combining recursive least squares (RLS) with modified nonlinear particle swarm optimization (NPSO) algorithm, is proposed. On this basis, another improved NPSO algorithm is also put forward, aiming at searching for the optimal proportional–integral (PI) controller gain of the nonlinear hydraulic system while giving comprehensive consideration to the system performance indexes. The system identification experiments and position tracking control are conducted, respectively. As indicated by the comparison with the least squares (LS), RLS, PSO, and RLS–LPSO results, the proposed method shows higher identification and control accuracy.     

HELOP: Multi-target tracking based on heuristic empirical learning algorithm and occlusion processing

Multi-target tracking is one of the important fields in computer vision, which aims to solve the problem of matching and correlating targets between adjacent frames. In this paper, we propose a fine-grained track recoverable (FGTR) matching strategy and a heuristic empirical learning (HEL) algorithm. The FGTR matching strategy divides the detected targets into two different sets according to the distance between them, and adopts different matching strategies respectively, in order to reduce false matching, we evaluated the trust degree of the target’s appearance feature information and location feature information, adjusted the proportion of the two reasonably, and improved the accuracy of target matching. In order to solve the problem of trajectory drift caused by the cumulative increase of Kalman filter error during the occlusion process, the HEL algorithm predicts the position information of the target in the next few frames based on the effective information of other previous target trajectories and the motion characteristics of related targets. Make the predicted trajectory closer to the real trajectory. Our proposed method is tested on MOT16 and MOT17, and the experimental results verify the effectiveness of each module, which can effectively solve the occlusion problem and make the tracking more accurate and stable.