【作者】 臧克江；

【导师】 郭艳玲； 马岩；

【作者基本信息】 东北林业大学 ， 机械设计及理论， 2012， 博士

【摘要】 编织型气动人工肌肉是气动人工肌肉的基本型和核心型,其基本特点是结构简单、功能特性优良。但是,编织型气动人工肌肉工作过程中受橡胶弹性变形、端盖的径向约束、橡胶与编织丝以及编织丝间摩擦等影响,导致精确建模十分困难,在此方面的理论研究还有待完善。编织型气动人工肌肉理论建模方法有两种：基于理想状态的能量守恒方法和基于理想状态的力平衡方法。这两种方法均假设编织型气动人工肌肉在工作过程中始终保持理想圆柱状态,而实际上,编织型气动人工肌肉两端受到端盖的径向约束作用,使其在工作过程中的几何形状为非理想圆柱,在两端部为回转曲面,因此,提高编织型气动人工肌肉几何形状的表达精度是建立其更加精确数学模型的关键。本文以编织型气动人工肌肉为对象进行了工作机理研究、理论建模研究以及设计研究。从编织型气动人工肌肉的功能实现和构成其关键部件的材料特性两个方面对编织型气动人工肌肉的工作机理进行研究。一方面,编织型气动人工肌肉实现其功能的基本原理是具有可变形的封闭容腔,在压缩空气的作用下封闭容腔变化,从而产生位移效应；位移变化的范围受气动人工肌肉结构的限制,输出力的大小与压缩空气压力大小和气动人工肌肉结构有关。另一方面,以层合理论、复合材料理论及薄壳理论等为基础,分析了编织型气动人工肌肉的柔性材料的特性。编织网对柔性件的变形起着决定性的作用,柔性件的平面刚度为零,它在不均衡外力作用下会产生“机构式”的变形,同时,编织型气动人工肌肉的每个稳定状态下编织网应该处于力的均衡状态,从而编织型气动人工肌肉工作机理得到了理论上的表达。利用缠绕理论、复合材料力学、薄壳理论以及微分几何等作为理论基础,对编织型气动人工肌肉端部进行了理论建模研究。编织纤维丝在编织型气动人工肌肉端部应为测地线缠绕。由于理论上端部曲线曲率发生了方向的变化,因此本论文建立的编织型气动人工肌肉端部数学模型由两部分构成：一部分是由最大直径到曲线曲率方向发生的变化点(拐点),此部分由理论分析得到；另一部分为拐点到端盖,这一部分用球面替代。尽管本文所建模型不是完全的理论解析,但在理论上使端部形状更接近精确解。同时,本文推导的编织角公式可以证明约束对编织型气动人工肌肉几何变形的影响作用。从设计的角度给出了编织型气动人工肌肉的各结构参数的设计计算公式,以及各几何参数间的关系。着重研究了影响编织型气动人工肌肉工作范围的重要参数——编织角,建立其计算公式,确定了编织角极值。给出了橡胶弹性和厚度对编织型气动人工肌肉工作特性的影响公式,研究了纤维丝间的摩擦对编织型气动人工肌肉工作特性的影响,给出了摩擦力的计算公式。利用ABAQUS软件从编织型气动人工肌肉结构出发对编织型气动人工肌肉进行了几何建模,通过分析计算得到了编织型气动人工肌肉的输出力、充气压力和长度之间的关系。同时,提取了编织型气动人工肌肉在工作状态下的外形尺寸、编织角、体积等几何参数。利用此模型模拟分析了约束对编织型气动人工肌肉工作特性的影响。设计制造编织型气动人工肌肉实验台,并进行了实验研究。通过编织型气动人工肌肉的静态工作特性实验结果与圆柱理想模型及有限元分析的对比,有限元分析得到的结果与实验结果更接近,这是由于在有限元分析过程中考虑了橡胶特性和端部约束对编织型气动人工肌肉输出特性的影响。同时,开展了约束对编织型气动人工肌肉输出特性的影响的研究,从有限元仿真和实验两个方面证明了约束使编织型气动人工肌肉输出特性降低的结论。更多还原

【Abstract】 Braided type pneumatic artificial muscle is the basic and core of pneumatic artificial muscle. The basic characteristic is simple structure and perfect performance. But the braided type pneumatic artificial muscle is under the influences of elastic deformation, friction and cover radial constraint in the work process of the pneumatic artificial muscle, the precise modeling is very difficult, the theory study remains to be perfect. There are two modeling methods for braided type pneumatic artificial muscle:the energy conservation law under ideal condition and the force balance law under ideal condition. The two laws are all assuming that braided type pneumatic artificial muscle always remaining in the ideal cylindrical state. In fact, there are constraints on both ends of pneumatic artificial muscle, the geometry in the process of the working is not the ideal column, the turning curved surfaces occur at the two ends. Therefore, the improvement of the geometry expression accuracy of braided type pneumatic artificial muscle is the key to establish the more precision mathematical model. This paper will study on the working mechanism, theory modeling and design research of braided pneumatic artificial muscle as the object.The working mechanism research is from two aspects including the function realization and the material characteristics of the key components. On one hand, pneumatic artificial muscle can realize its functions, its basic principle is the deformable closed chamber, under the compressed function, the air closed chamber change, causing the displacement effect; the displacement change ranges are restricted by the pneumatic artificial muscle structure, the output force is related to the pressure of compressed air and the structure of pneumatic artificial muscle.On the other hand, base on laminated theory, composite materials mechanics and thin shell theory, starting with the flexible characteristics mechanism of braided type pneumatic artificial muscle, the flexible material properties of braided type pneumatic artificial muscle has been analyzed. The weaving network has played a decisive role on the deformation of flexible pieces, the plane stiffness of flexible pieces is zero, it will produce "institution type" deformation in the balanced external force. At the same time, weaving network will be in the forces balance state under each stable state of braided type pneumatic artificial muscle. The theoretical expression of the mechanism of pneumatic artificial muscle has been got.Based on the work principle of braided type pneumatic artificial muscle, using winding theory, composite material mechanics, thin shell theory and differential geometry as theoretical basis, the theoretical modeling of the ends of braided type pneumatic artificial muscle has been studied. Braided fibers at the end of braided type pneumatic artificial muscle should be geodesics winding, because of the directional changes of the curvature will happen in theory, so the established mathematical model at the end of braided type pneumatic artificial muscle consists of two parts:one part is from the biggest diameter to the change point of the curvature direction (inflection point), the model of this part can be got by the theoretical analysis; The other part is from the inflexion point to the end cover, this part can be substituted for the spherical surface. Although the built model is not the completely theory solution in this paper, but the end shape is more close to the exact solution, at the same time, the constraints effect on the geometry deformation of braided type pneumatic artificial muscle can be proved.The design calculation formula of structural parameters of braided type pneumatic artificial muscle and the relationship between the various geometric parameters have been provided from the design view. The important parameter-the braiding angle which can influence the work scope of braided type pneumatic artificial muscle, has been focused on. The braiding angle calculation formula has been provided, the extreme value has been determined. The influence formula of rubber elasticity and thickness on the work characteristics of braided type pneumatic artificial muscle have been given; the friction influence between the fibers on the work characteristics of braided type pneumatic artificial muscle has been studied, and the calculation method of friction force has been provided.The geometry modeling of braided type pneumatic artificial muscle has been made from the structure of braided type pneumatic artificial muscle with ABAQUS. By analyzing and calculating, the relationship of output force, inflation pressure and length of braided type pneumatic artificial muscle has been obtained. At the same time, the contour dimension, braided angles and volume of braided type pneumatic artificial muscle in the working state also have been drawn. By using this model, the work characteristics influence of constraints on braided type pneumatic artificial muscle can be simulated.The test bench of braided type pneumatic artificial muscle has been designed and manufactured, and the experimental research has been done. Through the comparisons of the static working characteristics experimental results of braided style pneumatic artificial muscle, the ideal cylindrical model and the finite element analysis, the results of finite element analysis are more close to the experimental results, this is because rubber characteristics and end constraints have been considered in the process of finite element analysis of braided type pneumatic artificial muscle. At the same time, the constraint influence research of the output characteristic of braided style pneumatic artificial muscle has been developed. From two aspects of the finite element simulation and experiments, the conclusion that constraints can reduce the output characteristic of braided style pneumatic artificial muscle has been proved.更多还原