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蛇形机器人的动力学模型与其蜿蜒运动控制方法研究
Alternative TitleDynamic Model of a Snake-like Robot and Its Serpentine Locomotion Control
王智锋1,2
Department机器人学研究室
Thesis Advisor马书根 ; 王越超
ClassificationTP242
Keyword蛇形机器人 蜿蜒运动 动力学模型 基于能量的控制 连续体模型
Call NumberTP242/W39/2011
Pages115页
Degree Discipline机械电子工程
Degree Name博士
2011-05-25
Degree Grantor中国科学院沈阳自动化研究所
Place of Conferral沈阳
Abstract模仿生物蛇的无肢运动方式进行运动的蛇形机器人,因其诸多潜在的优点,如具有良好的环境适应性、运动稳定性、狭小空间可通过性、功能多样性等,越来越受到世界各国研究学者的关注。国内外几十家研究机构都已设计制造了各自的蛇形机器人,随着研究的深入进行,科研人员不可避免地需要解决“如何有效地控制蛇形机器人”这一问题。 生物蛇在各种环境中都能高效运动是在自然界中漫长进化的结果,而蛇形机器人因其复杂的运动动力学,如欠驱动、高维非线性、环境不确定性等,使得让蛇形机器人也获得高效的运动能力和环境适应性成为摆在研究人员面前的难题。由于蜿蜒运动作为生物蛇最典型的一种运动步态,对蜿蜒步态控制的研究一直是蛇形机器人控制研究的核心问题。所以本研究针对蛇形机器人动力学与控制中的问题,围绕蛇形机器人蜿蜒运动机理这一科学问题进行如下方面的研究: 1.对蛇形机器人动力学模型进行深入严格的理论分析 通过类比蛇形机器人与冗余度操作臂的机构、构形、运动学、动力学,建立蛇形机器人移动与操作的统一动力学模型。由移动与操作这两种状态动力学的统一关系,把蛇形机器人移动状态下的动力学模型解耦为与环境相关的外部动力学和与机器人本体机构相关的内部动力学。通过移动与操作统一动力学的建立与分析,揭示了蛇形机器人特殊的动力学结构,提供一个统一的视角理解链式机构移动与操作状态的动力学模型。统一模型研究过程中,引入微分几何方法将蛇形机器人的动力学建模转化为几何计算,并且把移动与操作的统一动力学模型问题归结为子流形问题。赋予了蛇形机器人动力学模型以几何意义,为深入研究蛇形机器人移动与操作统一动力学模型提供了数学分析的手段。 2.提出一种基于能量的蛇形机器人蜿蜒运动控制方法 蛇形机器人的运动最大的特性是环境与机器人本体相互作用,研究者无法孤立地去解决蛇形机器人运动机理中的个别问题,必须综合地考虑“环境-机器人”系统的动力学特征。而运动能量可以联系或描述蛇形机器人蜿蜒运动的各个方面,能量耗散描述蜿蜒运动中机器人与环境的交互作用,能量转换描述蜿蜒运动中机器人的动力学过程,能量平衡描述蜿蜒运动中机器人诸多关节之间的协调运动。从蛇形机器人蜿蜒运动中能量“耗散-转换-平衡”的角度去理解蜿蜒运动的机理,提出一种基于能量的蜿蜒运动控制方法——被动蜿蜒。通过输出关节力矩控制机器人蜿蜒运动, 由机器人的能量状态调整力矩的大小。蛇形机器人的蜿蜒运动控制既可实现对外部环境的适应、又可实现对内部机构本体的机械特性的适应。仿真和实验验证了蛇形机器人被动蜿蜒控制的有效性和适应性。 3.研究蛇形机器人的机械特性与蜿蜒运动控制参数之间的耦合关系 在蛇形机器人被动蜿蜒控制研究的基础上,通过蛇形机器人蜿蜒运动摆动频率的推导与计算,进一步研究机器人机构特性与蜿蜒运动控制律之间的耦合关系,以根据机器人的内部机构特征优化蜿蜒运动的控制参数。建立蛇形机器人自由摆动的连续体动力学模型,将被动蜿蜒控制方法的控制参数或控制量等效为机器人的机械参数(机构/结构参数),推导计算等效机器人系统的特征频率函数式。受自然界共振现象的启发,将随控制量变化的特征频率作为被动蜿蜒的控制频率,使得蛇形机器人的蜿蜒运动按照耦合系统的自然频率摆动。结果显示使用固有频率控制的蛇形机器人的蜿蜒运动在运动稳定性、启动时间等方面具有优势。由此实现了蜿蜒运动控制系统参数(即摆动频率)的选择由蛇形机器人的“控制-机构”耦合系统的特征决定。 总而言之,本文关于蛇形机器人动力学模型与蜿蜒运动控制的研究工作的目的为:更深入地理解蛇形机器人的运动机理,提高蛇形机器人的运动能力与环境适应性,使得仿生蛇形机器人的运动性能更接近于生物蛇的运动性能。
Other AbstractA snake-like robot, which can implement the snake motion, has many potential advantages, such as, the environment adaptability, the motion stability, the terrain trafficability, and the diverse functions. Many researchers focus their interests on the snake-like robot. Some dozens of institutes have developed their own snake-like robots. With the researches gradually deepened, the researchers inevitably meet a new problem, how to control the snake-like robots efficiently. Snakes can soundly adapt to different environments after long-time evolution in nature. Because of the complex dynamics of the snake-like robot, e.g., the underactuated degrees of freedom, the nonlinearity in higher dimensions, and the uncertainty of the environments, it becomes a challenging issue to construct an effective control method for the snake-like robots in order to exploit potential merits of the snake motion. Serpentine locomotion is the most representative and prevalent movement in the several locomotion modes of snakes, so researches on the locomotion control of the snake-like robot are almost concentrated on the serpentine locomotion. In the research, according to the problems of the model and control of the snake-like robot, we study the key points of the snake-like robots as follows: First, we analyze the dynamic model of a snake-like robot in theory strictly. By comparing the mechanism, configuration, kinematics, and dynamics of a snake-like robot with those of a manipulator, we establish an unified dynamic model for locomotion and manipulation of a snake-like robot. Based on the unified dynamic relationship between locomotion and manipulation, the dynamic model for locomotion of a snake-like is decoupled into the exterior dynamics relating to the environments and the interior dynamics relating to the mechanism of the robot. Through establishing and analyzing the unified model, the particular dynamic structure of the snake-like robot is revealed insightfully to some extent. In addition, a unified point of view to apprehend the dynamics of the locomotion and manipulation states of the articulated chain mechanism is offered. By using the geometric method, the dynamic modeling is transformed into the geometric calculation, and the unified dynamic model for locomotion and manipulation is considered as a submanifold problem. The dynamic model of snake-like robots is endowed with geometric meaning. The geometric point of view brings many mathematic methods into the analysis of the dynamic model of snake-like robots. Second, we propose an energy based control method for the serpentine locomotion of a snake-like robot. The locomotion of the snake-like robot relates to the following coupled aspects: the robot dynamics, environment interaction, and serpentine gait. The researchers should comprehensively consider the robot-environment dynamic system to solve the control problem, rather than be partial to whichever part. Energy plays an important role in the serpentine locomotion of a snake-like robot. The energy dissipation describes the environmental interaction; the energy transformation reflects the locomotion dynamics; the energy balance relates to the locomotion coordination. According to the principle of “dissipation-transformation- balance” of energy, we study the serpentine locomotion of a snake-like robot. An energy-based control method, named passive creeping, is proposed. This method controls the robot by using torque inputs, which are adjusted by the robot's energy state. Under the control of the passive creeping, the snake-like robot can adapt to various exterior environments and different interior dynamics through using the energy state. The simulations and experiments demonstrate the validity and adaptability of the passive creeping. Third, we study the coupling relationship between the mechanism characteristic of a snake-like and the control parameter of the serpentine locomotion. Inspired by the resonance in nature, we study the coupling relationship between the mechanism characteristic of the snake-like robot and the control law of the serpentine locomotion, through deducing and computing of the oscillation frequency of the serpentine locomotion of a snake-like robot. The continuum model of the snake-like robot in free oscillation is established. The control parameters and variables of the passive creeping control method are equivalently considered as the mechanism parameters, and then the characteristic frequency of the equivalent system of the snake-like robot is calculated. The natural frequency, which varies with the control variables, is chosen as the controlled frequency of the serpentine locomotion, so that the robot can wiggle at the characteristic frequency. The simulation results reveal the advantages of the method in the movement stability and the rise time. As a result, we can determine the parameter of the control system (i.e., wiggle frequency) based on the characteristic of the “control-mechanism” coupling system of the snake-like robot. In short, the objectives of the research on the dynamic model of a snake-like and the control method of the serpentine locomotion are as follows: 1) offering an insight into the locomotion mechanism of a snake-like, 2) improving the locomotion capability and the environment adaptability. As a result, the locomotion performance of snake-like robots can approach that of biologic snakes.
Language中文
Contribution Rank1
Document Type学位论文
Identifierhttp://ir.sia.cn/handle/173321/9403
Collection机器人学研究室
Affiliation1.中国科学院沈阳自动化研究所
2.中国科学院研究生院
Recommended Citation
GB/T 7714
王智锋. 蛇形机器人的动力学模型与其蜿蜒运动控制方法研究[D]. 沈阳. 中国科学院沈阳自动化研究所,2011.
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