一种可变构两栖蛇形机器人设计研究

目前国内外研发的两栖蛇形机器人大多水下和陆地结构为同一形态,这种结构往往保证了在陆地运动的灵活性,其水下结构较为简单,不能进行复杂的水下作业。针对这一情况,设计了一种适用于仿生蛇的可自主拆卸式外壳,实现仿生蛇形机器人的两栖变构要求,在适应水下复杂工况的前提下能够加装不同的机构和装置以实现不同的工作要求;在陆地运动时外壳及安装在外壳上的装置会影响仿生蛇的运动,通过仿生蛇类的蜕皮运动将外壳蜕去保证了仿生蛇在陆地运动的灵活性。仿生蛇的相邻关节之间通过滑槽连杆机构连接,使关节之间具有较高的自由度,能够实现蛇类的复杂运动,如攀爬、抬头等动作。仿生蛇头部设置有摄像头,能够实现画面的实时回传,并通过蓝牙遥控实现避障、管道巡检。     

一种蛇形机器人的结构设计与研制

蛇形机器人(以下简称机器蛇)因其身体细长和环境适应能力强的优点被广泛应用于不适宜人类工作的领域.介绍了一种仿生机器蛇的设计与制作.设计时选用体积小、动力足的P0090舵机作为机器蛇驱动,Atmega128和Atmega8单片机作为控制器.HPD8506A作为无线数据发射模块,完成PC与机器蛇的数据传输.根据舵机尺寸逆向设计关节、蛇头和蛇尾,采用正交关节连接方式装配,实现机器蛇蜿蜒、蠕动等多步态的移动,加载的红外避障传感器保障了机器蛇能安全躲避障碍物.此系统的研究为今后机器蛇在狭小管道或高空缆绳上攀爬并完成检测任务奠定基础.     

蛇形机器人的波形能量控制

蛇形机器人的步态控制理论大部分基于波的传递形式,借助自制蛇形机器人的结构对波传递过程中能量传递的过程进行了研究。根据蛇体三维运动特性,蛇游行时有前行、侧行两种基本形态,其他的运动模式均基于此两种形态。对蛇体运动形态进行控制,主要是在波形类型中采用波形正负交替（等峰值、差峰值）和行波（正弦波、三角衰减波）等进行蛇体运动控制,实现了机械蛇的蜿蜒游动控制。     

机器蛇的行波运动控制分析与研究

针对仿生机器蛇的行波运动控制,分析了其运动机理,在移动机器人仿真软件Webots中建立了其三维虚拟运动模型;基于机器蛇的行波运动控制函数,采用建立的三维虚拟模型对实现行波运动的控制参数进行了分析和实验验证,得到了控制参数与行波运动形状之间的关系;机器蛇行波运动控制的实验结果表明,基于上述分析的控制参数对机器蛇运动形状影响的结论,可以实现机器蛇任意期望形状的行波运动控制,并且具有较快的收敛速度。     

基于乐理的蛇形机器人控制方法研究

根据生物蛇和蛇形机器人的结构及运动特点,提出了基于乐理的蛇形机器人控制方法,定义了乐理的符号、规则与蛇形机器人控制过程的对应关系,编写了蜿蜒运动步态谱.“勘查者—I”蛇形机器人上实现了蜿蜒运动的控制. 给出了今后的研究方向．     

一个微小型仿蛇机器人样机的研究

本文从仿生机械学的角度出发,阐述了仿蛇机器人的 运动原理,给出了仿蛇机器人的结构和基本运动模式,在此基础上研制成微小型仿蛇机器人 样机,对样机进行了实验,结果表明,该样机能在平面上实现驱动运动并完成各项设定操作 ．     

蛇形机器人蜿蜒游动性能动力学仿真分析

模仿蛇在水中游动,设计了蛇形机器人仿真模型.通过蛇形曲线控制该机器人在动力学仿真水环境中实现蜿蜒游动.实验分析了蛇形曲线公式中起始弯角、S波个数、弧长变化率对蜿蜒游动性能的影响.实验结果表明:在一定范围内,增大蛇形曲线公式中起始弯角、S波个数、弧长变化率等参数的值,蛇形机器人的蜿蜒游动速率也随着增加.     

不同工况下仿生叶轮水上推进性能数值分析

研究采用蛇怪蜥甥踏水机理设计的轮-叶复合式仿生推进装置,针对实现推进性能最大化的仿生叶轮装置设计的难点,从减少叶片能量损失的角度设计了一种压水防溅型仿生叶轮结构,如何有效获取新型叶轮结构的水上推进性能,应用计算流体力学数值方法,通过构建不可压缩非稳态的N-S主控制方程,采用欧拉网格有限体积法的离散化处理方式,综合应用VOF模型和动网格技术,实现对新型仿生叶轮水上推进性能的数值模拟,着重讨论了不同转速ω和负载P下的仿生叶轮水平速度v1和水平位移s1的变化规律,研究仿生叶轮运动中压力场、速度场和气液相的分布特点,获得了转速ω和负载P对仿生叶轮水上推进性能的影响规律.仿真分析结果表明转速ω和负载P均存在一合理区间范围,使得新型仿生叶轮推进性能最优,仿真结果可为实现仿生叶轮模型水上推进性能最优提供了理论基础.     

色彩仿生设计方法及其应用研究

文章从仿生设计的相关概念入手,研究色彩仿生设计的方法与技术路径。从工业设计角度探索色彩仿生设计的要素、基本原理,进而研究色彩仿生设计的流程及方法,分析了色彩仿生设计中的色彩提取、色彩移植与优化、色彩优化后的演变等方法,并以案例分析进行相关观点及理论的论证。文章根据前期的研究提出色彩仿生设计应用的技术路径,并对技术路径在设计应用过程中的要求提出了具体的说明。     

六足救援机器人结构设计与步态分析

分析甲虫生物的原型特点和运动方式,对仿生甲虫六足救援机器人进行结构设计和样机设计,对甲虫生物原型设计了六足救援机器人。通过对仿生甲虫机器人三足运动步态,给出了直线行走时6条腿的末端位置矢量的表达式,结果证明仿生甲虫六足救援机器人的稳定性较强。     

Upper-body haptic system for snake robot teleoperation in pipelines

Snake robots have shown a great potential for operations in confined workplaces that are less accessible or dangerous to human workers, such as the in-pipe inspection. However, the snake robot teleoperation remains a nontrivial task due to the unique locomotion mechanism (e.g., helical motion) and the constraints of the workplaces including the low visibility and indistinguishable features. Most snake robot feedback systems are based on the live camera view only. It is hard for the human operator to develop a correct spatial understanding of the remote workplace, leading to problems such as disorientation and motion sickness in snake robot teleoperation. This study designs and evaluates an innovative haptic assistant system for snake robot teleoperation in the in-pipe inspection. An upper-body haptic suit with 40 vibrators on both the front and back sides of the human operator was developed to generate haptic feedback corresponding to the bottom and up sides of the snake robot, transferring the egocentric sensation of the snake robot to the human operator. A human-subject experiment (n = 31) was performed to evaluate the efficacy of the developed system. The results indicate that the proposed haptic assistant system outperformed other feedback systems in terms of both task performance and subjective workload and motion sickness evaluations. It inspires new control and feedback designs for the future snake robot in industrial operations.     

Snake terrestrial locomotion synthesis in 3D virtual environments

We present a method for a 3D snake model construction and terrestrial snake locomotion synthesis in 3D virtual environments using image sequences. The snake skeleton is extracted and partitioned into equal segments using a new iterative algorithm for solving the equipartition problem. This method is applied to 3D model construction and at the motion analysis stage. Concerning the snake motion, the snake orientation is controlled by a path planning method. An animation synthesis algorithm, based on a physical motion model and tracking data from image sequences, describes the snake’s velocity and skeleton shape transitions. Moreover, the proposed motion planning algorithm allows a large number of skeleton shapes, providing a general method for aperiodic motion sequences synthesis in any motion graph. Finally, the snake locomotion is adapted to the 3D local ground, while its behavior can be easily controlled by the model parameters yielding the appropriate realistic animations.     

Modeling and Control of Head Raising Snake Robots by Using Kinematic Redundancy

In this paper, we consider trajectory tracking control of a head raising snake robot on a flat plane by using kinematic redundancy. We discuss the motion control requirements to accomplish trajectory tracking and other tasks, such as singular configuration avoidance and obstacle avoidance, for the snake robot. The features of the internal motion caused by kinematic redundancy are considered, and a kinematic model and a dynamic model of the snake robot are derived by introducing two types of shape controllable point. The first is the head shape controllable point, and the other is the base shape controllable point. We analyzed the features of the two kinds of shape controllable point and proposed a controller to accomplish the trajectory tracking of the robot’s head as its main task along with several sub-tasks by using redundancy. The proposed method to accomplish several sub-tasks is useful for both the kinematic model and the dynamic model. Experimental results using a head raising snake robot which can control the angular velocity of its joints show the effectiveness of the proposed controller.     

Snake-like robots [Tutorial]

I (Hirose) started the biomechanical study using actual snakes and the design of snake-like robots in 1971. There were two reasons for the interest in this snake research: one is the scientific interest in the mechanism of the snake's motion and another is the engineering interest in the future applications of snake-like robots. There were already several studies on the motion of the snake; however, these were not satisfactory. The analytical method was not always consistent, and the analysis was done in somewhat artificial conditions, such as the motion of the snake in a maze with multiple pegs. So, I decided to perform a more precise analysis on standard serpentine motion. I was especially interested in the simplicity of its shape and the versatility of its function, because of its expected future applications. The simple cord-like body of the snake becomes a leg when it moves among rocks, a body when it moves from branch to branch, and a hand when it coils around a prey. From these features of the snake, I could imagine multiple applications in future. Figure 1 shows the expected applications I dreamed in those days. I used them in the oral defense of my doctor's degree dissertation in 1976. Figure 1(a) shows a downsized snake-like robot that can be utilized as an active endoscope to go into intestines. Figure 1(b) shows an active rope for a crane that automatically wraps around an object. Figure 1(c) is a polar exploration vehicle. It will glide on ice using ski blades, and the long body will enable it to cross over a crevasse. Figure 1(d) is an active hose that will approach a fire automatically using hydraulically actuated joints driven by the high-pressure water inside the hose. Figure 1(e) was drawn later for a children?s book, which shows a snake-like robot that does amphibious work.     

Video object tracking based on improved gradient vector flow snake and intra-frame centroids tracking method

Accurately tracking the video object in video sequence is a crucial stage for video object processing which has wide applications in different fields. In this paper, a novel video object tracking algorithm based on the improved gradient vector flow (GVF) snake model and intra-frame centroids tracking algorithm is proposed. Unlike traditional gradient vector flow snake, the improved gradient vector flow snake adopts anisotropic diffusion and a four directions edge operator to solve the blurry boundary and edge shifting problem. Then the improved gradient vector flow snake is employed to extract the object contour in each frame of the video sequence. To set the initial contour of the gradient vector flow snake automatically, we design an intra-frame centroids tracking algorithm. Splitting the original video sequence into segments, for each segment, the initial contours of first two frames are set by change detection based on t-distribution significance test. Then, utilizing the redundancy between the consecutive frames, the subsequent frames’ initial contours are obtained by intra-frame motion vectors. Experimental results with several test video sequences indicate the validity and accuracy of the video object tracking.     

Helical wave propagation motion for a snake robot on a vertical pipe containing a branch

Snake robots could be utilized in many fields because of their hyper-redundant properties, although there are still control problems when they are operated in complex environments. For example, a helical rolling motion has been used to climb a pipe. By using this kind of motion, a snake robot can move along the inside or outside of a pipe. However, this motion has limitations when the robot moves along a pipe containing a high gap or a branch point. In this study, we propose a type of motion for snake robots that involves wrapping around the outside of a pipe to overcome a branch point on it. This new motion uses a hyperbolic function to make a helical wave curve, which is then propagated by shifting the shape of the hyperbolic function along the body of the snake robot. The joint angles of the snake robot are derived by calculating the curvature and torsion of the curve on the basis of the formula of the continuous curve model. Finally, the results of simulations performed using the Robot Operating System and Gazebo programs are shown to validate the effectiveness of the new motion.     

The “Djedi” Robot Exploration of the Southern Shaft of the Queen's Chamber in the Great Pyramid of Giza,Egypt

There are many unanswered questions regarding the construction and purpose of the Great Pyramid of Giza, Egypt. A climbing robot called “Djedi” has been designed, constructed, and deployed to explore shafts of the queen's chamber within the Great Pyramid. The Djedi robot is based on the concept of inchworm motion and is capable of carrying a long reach drill or snake camera. The robot successfully climbed the southern shaft of the Great Pyramid, deployed its snake camera, and revealed writing not seen for thousands of years. This paper details the design of the robot, including climbing steps in the shaft and lessons learned from experimental deployment. © 2013 Wiley Periodicals, Inc.     

Dynamics and Motion Planning of Trident Snake Robot

The trident snake robot is a mechanical device that serves as a demanding testbed for motion planning and control algorithms of constrained non-holonomic systems. This paper provides the equations of motion and addresses the motion planning problem of the trident snake with dynamics, equipped with either active joints (undulatory locomotion) or active wheels (wheeled locomotion). Thanks to a partial feedback linearization of the dynamics model, the motion planning problem basically reduces to a constrained kinematic motion planning. Two kinds of constraints have been taken into account, ensuring the regularity of the feedback and the collision avoidance between the robot’s arms and body. Following the guidelines of the endogenous configuration space approach, two Jacobian motion planning algorithms have been designed: the singularity robust Jacobian algorithm and the imbalanced Jacobian algorithm. Performance of these algorithms have been illustrated by computer simulations.     

基于动态Snake模型的机械手运动轨迹视觉跟踪

针对机械手运动在图像序列空间的轨迹分布，提出一种基于时空轨迹线的动态Snake跟踪模型.定义相应的能量函数，可使其在机械手轨迹分布上取得极小，通过Snake能量的轨迹收敛实现对机械手运动点的跟踪定位.利用轨迹能量系数的动态调节，可避免Snake搜索过程陷入局部极小．使用平方轨迹最小二乘预测器对轨迹点位置进行预测，可提高Snake搜索的实时性和准确性．微装配机械手运动实验证明了该模型及跟踪算法的有效性.