Multi-UAVs collaborative tracking of moving target with maximized visibility in urban environment

Unmanned aerial vehicles (UAVs) with limited field of view are utilized to track a moving ground target continuously in urban environment. In urban environment, the sight lines of UAVs to the target are easily blocked by dense obstacles. To overcome this difficulty, the model predictive control (MPC) based collaborative tracking control is proposed with the goal of the maximum visibility of target. First, a visible probability based performance index is proposed, and the flight planning strategy of maximum the phase difference is obtained as a consequence. Then a centralized MPC based collaborative control problem is solved to obtain the optimal control signals. The joint cost function consists of four parts which aims at tracking target, avoiding collision, avoiding the blind area and maintaining the maximum visibility, respectively. The effectiveness of the proposed collaborative strategy is verified by simulation. Compared with the traditional MPC-based collaborative method, the proposed maximum visible probability index provides an optimal dynamic formation structure for multi UAVs to guarantee the tracking of the moving ground target in urban environment.     

Quadcopter formation flight control combining MPC and robust feedback linearization

This paper presents an integrated and practical control strategy to solve the leader–follower quadcopter formation flight control problem. To be specific, this control strategy is designed for the follower quadcopter to keep the specified formation shape and avoid the obstacles during flight. The proposed control scheme uses a hierarchical approach consisting of model predictive controller (MPC) in the upper layer with a robust feedback linearization controller in the bottom layer. The MPC controller generates the optimized collision-free state reference trajectory which satisfies all relevant constraints and robust to the input disturbances, while the robust feedback linearization controller tracks the optimal state reference and suppresses any tracking errors during the MPC update interval. In the top-layer MPC, two modifications, i.e. the control input hold and variable prediction horizon, are made and combined to allow for the practical online formation flight implementation. Furthermore, the existing MPC obstacle avoidance scheme has been extended to account for small non-apriorily known obstacles. The whole system is proved to be stable, computationally feasible and able to reach the desired formation configuration in finite time. Formation flight experiments are set up in Vicon motion-capture environment and the flight results demonstrate the effectiveness of the proposed formation flight architecture.     

Model predictive tracking control with disturbance compensation for wheeled mobile robots in an environment with obstacles

This paper explores the trajectory tracking control problem for a wheeled mobile robot (WMR) in an environment with obstacles and unknown disturbances. A fixed-time extended state observer is presented, which is utilized to estimate unknown disturbances and improve the convergence speed of estimation errors. By introducing the obstacle avoidance cost, a model predictive controller with disturbance compensation is proposed to guarantee desired tracking performance in the presence of obstacles. The proposed method is analyzed for recursive feasibility and closed-loop system stability subject to unknown disturbances and obstacles. Finally, both simulation and experiment are conducted to express the satisfactory tracking effect of the developed approach.     

DP-based path planning of a spherical mobile robot in an environment with obstacles

A direct approach to path planning of a 2-DOFs (Degrees of Freedom) spherical robot based on Bellman?s dynamic programming (DP) is introduced. The robot moves in an environment with obstacles and employs DP to find optimal trajectory by minimizing energy and preventing obstacle collision. While other path planning schemes rely on pre-planned optimal trajectories and/or feedback control techniques, in this approach there is no need to design a control system because DP yields the optimal control inputs in a closed loop (feedback) form. In other words, after completing the DP table, the optimal control inputs are known for every state in the admissible region and the robot can move toward the final position without colliding with obstacles. This enables the robot to function well in semi- or even non-observable environments. Results from several simulated experiments show that the proposed approach is capable of finding an optimal path from any given position/orientation towards a predefined target in an environment with obstacles within the admissible region. The method is very promising compared to other path planning schemes.     

当前烟草企业培训问题浅析

随着国家烟草行业改革的不断深入,烟草行业培训也从培训内容、培训形式、培训资源、培训队伍等方面逐步转变。行业培训工作是提高员工素质的基础,也是实现卷烟上水平的重要保障。从当前烟草企业培训重视程度、培训形式和内容、培训队伍、培训效果评估和激励机制等问题出发,提出了解决问题的相应对策,为中国烟草企业教育培训提出一些思路。     

三本院校学生记者队伍建设探索——以宿迁学院为例

三本院校的学生记者队伍存在许多阻碍其发展的现实问题。我院以规章制度建设为工作基础,以文化内涵建设为核心任务,以人才队伍培养为目标关键,将对外交流学习作为重要途径,走出了一条大学生记者队伍建设的可喜路子。     

基于心理契约的企业中层管理者激励体系研究

在企业的日常管理活动中,中层管理者是承上启下的关键所在,企业的战略实施、员工激励、团队建设等管理问题无不与之密切相关。但是,对中层管理者的激励却成为企业持续经营过程中面临的一个难题,集中表现在中层管理者离职率上升、工作积极性下降等现象上。从契约理论的角度审视此问题,心理契约破裂是问题产生的关键,以此为基础建立柔性化的人力资源激励体系是解决问题的路径选择。     

基于偏序集的微信公众号传播力评价研究

[目的/意义]对微信公众号推送信息传播力进行客观、科学的评价,促进自媒体团队更加高效地利用微信公众平台传播信息.[方法/过程]利用可加偏序集理论,建立了蕴含权重的偏序集评价方法.首先,选定评价目标集,收集20个科技类微信公众号原始数据;其次,通过给定权重顺序,构造新的偏序集;最后,得到Hasse矩阵,由Hasse矩阵绘...     

科研团队隐性知识共享的结构性要素——一个社会网络分析案例

在回顾显、隐性知识管理文献的基础上总结了科研团队隐性知识共享的特点.利用社会网络分析,结合案例重点,研究了影响科研团队隐性知识共享的结构性要素.针对这些要素可能产生的障碍提出了相应的解决措施.     

中国导游人才发展的主要障碍与解决思路

从中国导游人才队伍的现状出发,分析了当前导游人才发展的主要障碍,并结合我国旅游业发展的实际,探讨了导游人才发展所面临问题的解决思路。     

科学基金制度对基础科研合作的引导效用分析

摘要：本文首先简要分析了合作研究在基础科学发展中的重要作用,在此基础上分析了基础科研合作所面临的主要阻碍是基础科研领域的“市场失效性”及基础科研团队的“专业单一性”;进而分析了科学基金制度在推进基础科研合作和营造合作良好环境方面的突出效用,分析了基金制度对于基础科研合作的促进机理。     

Optimal formation control and collision avoidance in environment with multiple rectangle obstacles

This paper addresses formation control problem with collision avoidance for general linear multi-agent systems via an optimal control strategy. In the proposed optimal control strategy, a novel potential function is designed to accomplish formation of multi-agent systems (MASs) with obstacle/collision avoidance capability, which can avoid rectangle obstacles accurately. In this potential function, a novel relative velocity based self-adaptive detection region is proposed to avoid collisions with adjacent agents. Moreover, a non-quadratic avoidance performance index is constructed based on inverse optimal control approach. Then, the optimal control strategy is designed to guarantee the asymptotic stability of the closed-loop system and optimality of the proposed performance index. Finally, a simulation example is given to illustrate the efficiency of the proposed approach.     

科研项目从经费管理向成果管理的改革

科研项目经费管理制度在实施中不同程度地存在的项目经费开支不符合规定的问题,项目经费管理制度本身的不合理,缺乏对项目承担人的劳动补偿机制是造成问题的重要原因。建立以科研项目成果管理为内容的新机制是解决问题的关键。政府方面,以科研项目的成果管理为目标,确立政府花钱购买科研成果的观念,确立科研项目主体双方平等的法律地位。政府把科研项目管理作为政府采购合同来管理,通过控制科研经费的支付,监督科研项目的进展情况,保障科研成果的质量。项目承担人在保证交付合格的科研成果的前提下,享有科研经费的支配权和所有权。     

探索高级英语教学中“产出导向法”的应用

针对外语教学中学用分离的状况,文秋芳团队创建了“产出导向法”理论体系。为改善课堂教学效果,提高学生语言产出水平,高级英语课基于“产出导向法”的“驱出-促成-评价”流程设计语言活动,进行单元教学实践。“产出导向法”明确了教与学的目标,为学生完成产出任务搭建了脚手架。     

Distributed RISE control for spacecraft formation reconfiguration with collision avoidance

In this paper, we investigate the distributed formation reconfiguration problem of multiple spacecraft with collision avoidance in the presence of external disturbances. Artificial potential function (APF) based virtual velocity controllers for the spacecraft are firstly constructed, which overcome the local minima problem through introducing auxiliary inputs weighted by bump functions. Then, based on the robust integral of the sign of the error (RISE) control methodology, a distributed continuous asymptotic tracking control protocol is proposed, accomplishing both formation reconfiguration and the collision avoidance among spacecraft and with obstacles. Furthermore, using tools from graph theory, Lyapunov analysis and backstepping technique, we show the stability and collision avoidance performance of the closed-loop multiple spacecraft system. Numerical simulations for a spacecraft formation are finally provided to validate the effectiveness of the proposed algorithm.     

虚拟R&D团队成员间知识共享障碍与利益协调方案

虚拟R&D团队是成员跨越时间、空间和关系的界限,通过技术的使用以完成相互依赖的R&D任务的团队,它的特征是"虚拟性".依据虚拟R&D团队的内涵和特征,揭示出团队成员之间的知识共享存在共享激励、囚徒困境、道德风险、合作关系不确定、共享效率等障碍,并提出了促进虚拟R&D团队成员间知识共享的五个相关对策.     

团队反思对创新项目团队绩效的作用研究

对项目团队的有效管理是创新项目的成功关键因素,我国在这方面的研究尚显不足。回顾了国外关于团队反思的研究,分析和总结团队反思对创新项目绩效的影响机制,并结合团队反思的前置变量和中介变量,归纳成一个较为全面、综合的概念模型。最后,结合我国的文化背景特征与创新项目的特点和要求,对进一步的研究提出了建议。     

海尔全球化品牌战略:人单合一

“人单合一”是海尔在未来的全球化品牌战略阶段取胜全球市场的发展模式。分析了海尔“人单合一”的基础、本质和实践，“人单合一”是流程再造创新与SBU战略目标一致的结合，“人单合一”的客户经理、产品经理和型号经理三种经营单元，是流程化的经营单元PBU。通过具体分析海尔在快速响应市场需求，客户经理、产品经理、型号经理相互咬合实现订单的市场链机制指出：“人单合一”激励了企业从研发到生产过程每个职位每个员工的创新，为海尔参与并赢得国际市场竞争、成为真正的国际名牌提供了有力的保障。     

土壤学理论和技术创新促进区域农业持续发展和地方经济建设

黄淮海地区是我国第二大平原,在国家粮食安全和国民经济发展中有不可替代的战略地位。黄淮海平原主要由黄河、淮河、海河等多沙性河流冲积而成,历史上长期面临旱、涝、盐碱、风沙等农业生产问题。在此背景下,以中科院南京土壤所熊毅院士为首的研究队伍,于1963年进驻黄淮海平原,创建了"井灌井排"治理盐碱的核心技术。20世纪80年代初,以中科院南京土壤所为主的研究队伍再次会聚封丘,开展治理旱涝灾害和改良低产土壤工作,并由此建立了中科院封丘农业生态实验站(简称"封丘站")。自建站以来,尤其是近10年来,在国家科技部、国家自然科学基金委、农业部和中科院等大力支持下,以封丘站为野外基地,国内科研人员联合开展了系统研究和技术研发,取得了一系列研究成果。在基础理论研究方面,揭示了潮土障碍形成机制和土壤质量演变规律,解析了土壤有机质的周转规律和土壤结构的形成机制,提出了土壤地力定向培育的对策;在技术研发和应用方面,创建了土壤地力培育和大面积均衡增产栽培技术,并在河南省20多个粮食生产重点县示范推广。通过与地方政府和企业合作,研发了道地金银花和树莓规范化、标准化高效栽培技术,建立了"企业+科研+基地+农户"的发展模式,为国家粮食安全保障体系建设和地方经济发展做出了重要的贡献。     

团队绩效衡量模型研究

团队对于企业的发展日益重要,绩效衡量是团队取得成功的重要因素。从团队性质和团队绩效影响因素出发,介绍了西方管理理论中一系列针对团队绩效衡量、具有代表性的研究成果,在此基础上,分析了相关的整合模型,从个人与团队这两个层次和团队过程的角度提出了概念模型分析框架。