【作者】 张峥炜；

【导师】 李贻斌；

【作者基本信息】 山东大学 ， 控制理论与控制工程， 2012， 博士

【摘要】 群机器人系统是一类特殊的多机器人系统,由许多相对简单的个体组成,主要研究如何设计个体,使得通过个体之间或者个体与环境之间的局部交互涌现出期望的系统行为。群机器人系统研究的兴起源于生物学,尤其是社会性昆虫的启发,因此具有典型的分布式系统特征。相比于传统的个体机器人系统,群机器人系统在灵活性、鲁棒性、分散性以及自组织性等方面表现出特有的优势,潜在应用领域非常广阔。群机器入学的研究注重个体机器人的物理实现以及个体交互、个体与环境交互的物理实现,目前已成为研究的热点,但是该方向是一门崭新的学科,尚未形成系统的理论,仍有很多问题亟待研究与解决。例如对于给定的系统行为,该如何设计底层的交互机器人,使得系统行为在底层个体的交互中涌现出来,是群机器人学研究中一个尚未解决的问题。群机器人学是一门应用性的学科,对该学科的研究往往通过结合具体任务深入探究其内在机理。本文通过结合群体搭建任务,研究一群相对简单的机器人如何以分散控制的方式并行搭建出具有几何形状的结构。该任务特别要求搭建过程时空的协调,本文针对群体搭建过程中若干协调机制问题进行了相关探讨与研究,内容如下：(1)针对现有模板机制在群体搭建任务中存在的不足,受蜜蜂视觉导航机制的启发,提出了群体搭建机器人以环境中自然存在的一些显著特征为模板,实现了机器人搭建过程的视觉导航与定位,完成了砖块指定地点的搁放,并实现了群体搭建过程的协调,建立起视觉模板机制。直线墙搭建实验结果表明视觉模板机制是可行的。该机制的优点是无需事先对环境进行布置,无需机器人之问通讯,并对多机器人的控制有很好的扩展性,适应于未知环境中的群体搭建工作。(2)在视觉模板机制的基础上,提出了基于自身的时空可变模板机制,使模板从环境的固定地标中解脱出来,为群机器人搭建更为复杂的结构提供了可能。同时作为模板的机器人并不是固定不变的,所有机器人都可以充当模板,这就降低了系统中因为个体失效导致整个系统失效的风险,提高了系统的鲁棒性,使之成为更为一般化的搭建方法。(3)针对现有的基于Stigmergy的机制在群体搭建任务中存在的不足,提出了基于机器人评估能力的群体搭建时空协调机制。该机制可通过赋予机器人感知环境、评估系统当前状态的能力,简化对搭建规则的依赖,即机器人利用简单的搭建规则即可完成群体搭建任务,实现群体搭建过程时空的协调。(4)针对基于信息素的群体搭建机制,探讨了群体搭建过程中出现的涌现行为。通过研究白蚁王族巢室的搭建过程,抽象并建立了基于智能体的环境动力学模型以及个体行为模型,针对不同的目标结构,设计出机器人不同的行为模型,分析并探讨了简单规则产生复杂全局模式的原因等问题。更多还原

【Abstract】 A swarm robotic system is a special type of multiple robot system, which focuses on the study of how a large number of relatively simple physically embodiment agents can be designed such that the global pattern of the system emerges from the local interactions among agents and between agents and the environment. Swarm robotics takes its inspiration from biology, in particular social insects, therefore, it exhibits many functional properties including flexibility, robustness, decentralization, self-organization, etc., which are desirable properties required in many wide-ranging potential applications.Swarm robotics is a novel approach to the coordination of large number of robots. Researchers typically focus on one problem domain to study the underlying properties of system. This dissertation focuses on the problem of collective construction which is concerned with the building of a geometric structure with a collection of robots working in parallel, without centralized control. Robots in the swarm have to coordinate their building activities both in space and time such that a consistent structure can be achieved. For a given structure, how the robot can be designed such that the given structure can be built is still an open question in swarm robotics. Although it has drawn increasing attention over the last decade and many achievements have been made, swarm robotics is still a brand new research field and no systematic theoretical methodology has been established. This dissertation focuses on the coordination mechanisms involved in collective construction. The main works and contributions are summarized as follows:(1) Inspired by honeybee visual navigation behavior, a visual template mechanism is proposed in which a natural landmark serves as a visual reference or template for distance determination as well as for navigation during collective construction. This mechanism can make use of an interesting landmark, reference point or salient object in the construction environment which allows for robots manipulating homogeneous bricks in a non-communicative way. Therefore, such a mechanism has an obvious appeal to those researching collective construction for applications in unknown environments.(2) The visual template mechanism allows the robots to finish simple construction tasks. But when it comes to a more complicated task, robots would become complex. Complexity refers to the hardware and software complexity of the robots. Aiming at the drawbacks of the visual template mechanism, a spatio-temporal varying template mechanism is proposed which uses the robot itself as a template without referring to the outside world. This self-generated template varies spatially and temporally when the robot varies in position. This means the various moving pattern of the robot makes a variety of template patterns. This mechanism is a more general mechanism because it is possible for robots to build complex structures. Furthermore, the robot serving as a template is not fixed, and all the other robots could possibly become a template. This role-changing mechanism makes the system less prone to system failure when the individual malfunctions such that the robustness of the system can be increased.(3) A new spatio-temporal coordination mechanism is proposed in the case of stigmergy-based collective construction. The originality of the work lies in the increase in the capabilities of the construction robot. Endowed with the system state assessment capability, construction robots can collective build the desired structure using only a simple rule set.(4) A preliminary study of the emergence behavior in collective construction is given in a pheromone-based collective construction system. First the termite’s royal chamber construction is studied and then agent-based collective construction model is abstracted and established. This model consists of two parts:one is a dynamic model of the environment and the other is an individual behavior model. Based on this model, several different objective structures are studied and how simple rules give rise to a complex global pattern is also discussed.更多还原