节点文献
攀爬蛇形机器人的研究
Study on Climbing Snakelike Robot
【作者】 孙洪;
【导师】 马培荪;
【作者基本信息】 上海交通大学 , 机械电子工程, 2007, 博士
【摘要】 蛇形机器人是仿生机器人研究中很活跃的一支,至今已有数十台蛇形机器人样机问世。这些样机能实现蜿蜒爬行、侧滑、翻滚、避障等二维平面运动,大部分已经具备抬头、爬台阶、翻越较低障碍等在三维空间中的运动能力。尤其近几年研制的一些蛇形机器人样机,其功能更加地具有针对性和多样化,有的已经能够垂直攀爬到数米的高度。目前实现的攀爬分为两种,内攀爬和外攀爬。内攀爬是在攀爬对象内部进行的,如管道内部、两面墙之间,蛇形机器人通过将竖直的身体横向变形成支架状撑住攀爬对象内壁,然后采用在平面中的履带传动、蠕动、翻滚等运动方式上下移动。外攀爬是沿攀爬对象外壁进行的,蛇形机器人通过缠绕附着在攀爬对象外表面,然后采用一定的步态上下攀爬。内攀爬对于大部分蛇形机器人比较容易实现,而外攀爬与蛇形机器人的结构和外形设计有很大关系,既要求其具备灵活的三维运动能力,又要求能够附着在攀爬对象上而不下落。国内外目前仅见有一个实现外攀爬的实验,而关于外攀爬的理论研究,更是一片空白。本论文即面向这一课题进行初步探讨,针对研发在垂直外攀爬方面有较大优势的攀爬蛇形机器人,提出一种新的构架模式,基于此种构架模式的攀爬蛇形机器人结构简单、便于控制,能够更为轻松和灵活地附着于攀爬对象外壁。接着对攀爬蛇形机器人爬树的基本姿态进行静态平衡机理分析,为攀爬蛇形机器人样机的研制和攀爬对象的选择提供理论依据。然后以平面蠕动步态为基础为其规划一种空间中的蠕动步态,并对这一步态进行运动机理分析,给出运动波传递的运动方程,基于此运动方程,攀爬蛇形机器人能够实现在树干上的攀爬。本文主要研究内容如下:(1)提出一种新型的、具备较大三维灵活性的、模块化的执行单元的结构设计。针对目前相关领域研究蛇形机器人样机所存在的问题,以平行连接和正交连接为基础,提出一种P-R模块设计,其结构与平行或正交连接相似,而一个P-R模块与一个万向节的工作空间相当。以P-R模块方式连接的蛇形机器人,既可以作为平行连接的蛇形机器人,又可以作为正交连接的蛇形机器人,在功能上,又相当于万向节连接的蛇形机器人,但是,其结构与控制却很简单,比真正的万向节更容易实现。因此基于此种构架模式的攀爬蛇形机器人结构简单、便于控制,能够更为轻松和灵活地附着于攀爬对象外壁,在垂直攀爬方面有独特优势。(2)对攀爬蛇形机器人在树干上的缠绕攀爬动作进行静态平衡机理研究。基于P-R模块的攀爬蛇形机器人CSR,具有较好的三维灵活性,能够实现爬树功能。CSR静止缠绕在树干上所形成的等距螺旋姿态是其爬树动作的最基本姿态。针对等距螺旋轨迹进行分析,得到该轨迹的螺旋倾角与P、R各关节转角之间的关系,这样,在实际应用时,只要知道CSR在特定圆柱上静止缠绕形成的螺旋线的倾角θ,则通过控制各关节的转角,可令CSR形成相应的形状静止附着于圆柱表面。针对CSR静止缠绕在树干上所达到的力学平衡进行研究,得到CSR和树干的所有参数之间的函数关系,并分别进行两两关系的分析,得到各参数的边界值,为攀爬蛇形机器人样机的制作和攀爬对象的选择提供了理论依据。(3)对缠绕攀爬动作进行步态规划。采用三连杆组成的蠕动步态作为CSR爬树时的步态,攀爬中仅P关节参与运动波的传递,本文规划了整个三连杆运动波的传递过程,并给出运动过程中各关节位置和转角的状态。在运动波传递过程中,CSR将从一个等距螺旋位置到达下一个等距螺旋位置,二者倾角相同,但不重合,CSR既是通过一个个位置变换实现向上攀爬。三连杆蠕动步态对于攀爬蛇形机器人CSR来讲,是一种动作简单、便于控制、稳定性强、适用环境广泛以及节能的步态。(4)对缠绕攀爬动作进行运动机理研究。针对CSR在空间中的三连杆蠕动步态,采用四连杆机构对波形传递过程进行研究,给出组成运动波形的各连杆间空间夹角之角位移间的关系、各角位移相对变化率、运动波初始角的确定以及步长。通过仿真图形分析得知在攀爬过程中,各空间角角速度变化平稳,是适合CSR攀爬的步态,但由于缠绕形成的是空间角,且参与运动波传递的只有P关节,其运动波形成的四连杆机构中各夹角不能像在平面中一样任意取值,各角度只有在某个特定的区域内变化,才能保证三连杆运动波的顺利传递。(5)仿真与样机实验。通过ADAMS的仿真和蛇形机器人样机的实验,验证上述研究结果的正确性。本文针对能够实现外攀爬的攀爬蛇形机器人从结构设计的优化到攀爬行为的实现进行了较为全面和深入的研究,为该课题更深更广层次的研究提供了有利的参考。
【Abstract】 The research of snakelike robots is a branch of bionic robots’research. There are a good many of prototypes in the world till present. The locomotion modes of the prototypes are serpentine crawl, sideslip, side roll, et al on a plane. And most of them have the abilities of raising their heads, climb up steps, crossing low obstacles, et al in the three-dimensional space. Especially in recent years, the new developed snakelike robots have more aimed and versatile functions. Some of them can climb up to a level of several meters in the vertical direction. The climbing that realized till now includes inner-climbing and outer-climbing. The inner-climbing refers to the climbing that proceeds in the inner space or surface of climbing object, such as in a pipe or between two walls. The snakelike robots stake on the inner surface of the climbing object by shaping as brackets, then they can move up and down by track driving, inchworm locomotion, rolling et al. The outer-climbing refers to the climbing that proceeds on the outer surface of the climbing object. The snakelike robots twist on the climbing object and climbing up and down by certain locomotion gait. The inner-climbing is much easier to be realized for most of snakelike robots while the outer-climbing is not. The realizing of outer-climbing mostly depends on the structure and the appearance design of the snakelike robot. It is strongly required that the snakelike robot has agility locomotion ability in three-dimension space and it can attach on the surface of the climbing object steadily and will not drop.Only one experiment of snakelike robot realized outer-climbing in the world. And theoretical study on it is blank. This paper will focus on the outer-climbing of snakelike snake. To develop a kind of climbing snakelike robot that has great advantage in vertical outer-climbing, it presents a new mode of structure. A climbing snakelike robot that based this structure mode has simple structure, is easy to be controlled and could steadily attach on the surface of the climbing object more agility and easier. Then it analyzes the mechanism of the static balance of the basic pose while climbing snakelike robot climbing a tree, which provides theoretical rules for developing a climbing snakelike robot or choose climbing object. Following is planning a spatial inchworm locomotion gait for it to climb a trunk which bases the inchworm locomotion gait on a plane. Then it analyzes the kinematics mechanism of the gait, presents the locomotion equations of the wave. Base on the locomotion equations, the snakelike robot could realize the climbing on a trunk.The studies in this paper mainly focus on followings.(1) Presents a new and modular structure design of execution unit, which has rather great agility in three-dimension space.against the problems that exist in the study of climbing snakelike robots at present, this paper presents a design named P-R module, who is similar to parallel and orthogonal link ways, but the operating space of the module is similar to a universal joint. So a snakelike robot that links by P-R modules both can act as a parallel linked one or a orthogonal linked one. But on the other hand, it nearly equal to a universal joint linked one in function. And it has simple structure and is easy controllable, so it is much easy to be made than universal joints linked one. A climbing snakelike robot based P-R modules has simple structure and is easy to be controlled, it could steadily attach on the surface of the climbing object more agility and easier, so it has unique dominance on vertical climbing.(2) Study on the mechanism of static balance of climbing snakelike robot climbing a trunk.CSR that based on P-R modules has good agility. It can climb trees. The pose that it twists on a trunk steadily and forms an isometric spiral is the basic pose of climbing trees. Analyzing the helical track, it gains the relationship of the obliquity of helical curve and each P, R joints’rotation. Then in the course of practise, only to know the obliquity of the helical curve that CSR rolling on the trunk, by controlling the rotation of each joints, CSR will form the corresponding shape and attach on the surface of the trunk.Studing on the mechanical equilibrium that CSR on the trunk, it gain the function relationship between the parameters of CSR and the trunk, analyzing the soecufuc relationships between every two parameters, it gained the border value of each parameters, which provide theoretical rules for developing a climbing snakelike robot or choose climbing object.(3) Gait plan.It is planed a three-link formed motion wave inchworm locomotion gait for CSR climbing trees. In the procession of climbing, only P-joints engage in the delivery procession of locomotion wave. It plans the full procession of motion wave deliver, and gives the position and rotation of each joint. In the procession of motion wave pass, CSR will arrive to another isometric spiral position from a former one. The two isometric spiral have the same obliquity, but they are not coincidence. CSR moves from one to another to realize climbing.For CSR, the three-link formed motion wave inchworm locomotion gait is a kind of simple action, strong stability, wide suitable use and energy conservation gait.(4) Study on the mechanics of climbing locomotion.It analyzes the inchworm locomotion in three-dimension space whose motion wave is formed with three links by four-link mechanism. The relationship of angular displacement of relative angles between two adjacent links, the relative change rate of the angular displacement, the equations of initial angular of the motion wave and the length of one step are presented.By analyzing the figures of simulation, it is gained that the spatial inchworm locomotion gait is suitable for the snakelike robot to adopt while climbing trees because of the smooth change of the spatial angulars’rotational velocity. But because these are spatial angulars that formed by twisting, and only P-joints engage in the delivery procession of locomotion wave, the relative angles between two adjacent links that form the locomotion wave could not sampling as arbitrary as they are just on a plane. The three-link locomotion wave can transfer continuously only when each of the relative angles varies in its specific range.(5) Simulations and prototype experiments.Simulations by software ADAMS and prototype experiments are presented to demonstrate and validate the concepts and the modeling assumptions.This paper studies on the climbing snakelike robot. From the optimization of the structure design to the realization of the behavior of climbing a tree, it gives rather full and deep studies. These studies provide valuable preferences for wider and deeper climbing snakelike robot research.
【Key words】 climbing snakelike robot; outer-climbing; P-R module; static balance; gait plan; mechanics of locomotion;