基于Webots的蛇形机器人翻滚运动仿真及实现

针对蛇形机器人的侧向翻滚运动,给出一种建立正交关节蛇形机器人三维空间运动模型的方法,提出了一种更为简单的实现蛇形机器人侧向翻滚运动的舵机输入函数.通过选择不同的控制参数,可以实现蛇形机器人"U"字形和"V"字形侧向翻滚运动.在Webots移动机器人仿真软件上进行正交关节蛇形机器人翻滚运动仿真,并在蛇形机器人本体上进行试验,验证了所提控制规律的有效性.     

基于Hopf振荡器实现的蛇形机器人的步态控制

针对生物蛇不同步态的运动特点,提出了一种基于Hopf振荡器实现的蛇形机器人的中枢模式发生器(CPG)运动控制方法.首先,利用具有非线性极限环特性的耦合的Hopf振荡器构建出能够实现蜿蜒运动和侧向蜿蜒运动两种步态的链式网络模型.然后,根据动力学仿真软件建立机器人的虚拟样机,利用模型中振荡器的输出作为蛇形机器人分布式多冗余度关节的控制信号来驱动前进,成功实现了以上两种运动方式,并讨论了CPG的模型参数与机器人前进速度的关系.最后,在实物样机上的实验进一步验证了所提出的方法在实现蛇形机器人多种步态控制方面的有效性.     

蛇形机器人在缆索检测中螺旋滚动步态的研究

提出了一种检测桥梁缆索的方式,利用蛇形机器人在缆索上螺旋滚动步态的优点,检测缆索表面和内部损伤,克服传统的桥梁缆索检测方法的不足。研究了蛇形机器在缆索上螺旋滚动步态的实现,确定了螺旋滚动曲线的参数与蛇形机器人螺旋滚动姿态的关系。通过参数的调整和优化,使蛇形机器人既不会抱得过紧而损伤缆索,而降低蛇形机器人的运行速度和消耗蛇形机器人更多能量,又不会抱得太松而使蛇形机器人从缆索上滑落,而降低蛇形机器人在缆索上运动的安全性。最后通过Webots仿真软件的模拟真实环境,表明了蛇形机器人可以在桥梁缆索上实现螺旋运动,且螺旋运动可以适应不同直径的缆索,通过改变参数,可优化和调整蛇形机器人的螺旋形状,使蛇形机器人模块选择灵活、运动的安全和高效。     

蛇形机器人蜿蜒运动控制分析

针对蛇形机器人的蜿蜒运动控制,首先分析了关节角度约束对运动控制函数参数取值的限制,确定了满足机械结构的运动控制参数范围;之后在Adams仿真环境下,建立蛇形机器人的三维虚拟运动模型,进行蜿蜒运动仿真,通过分析幅值控制参数对蛇形机器人弯曲度、运动速度和运动轨迹偏移的影响,提出了调整幅值参数的方法;实验结果表明,调整方法的有效性,从而实现蛇形机器人蜿蜒运动控制的优化。     

一种基于空间连杆机构的蛇形机器人

提出了一种基于空间连杆机构的蛇形机器人模型．该蛇形机器人各骨节间通过万向铰链连接，每节安装两个微型伺服电机，电机带动曲柄转动，曲柄经两端为球铰的连杆驱动另一骨节运动．通过两个电机的耦合驱动，该蛇形机器人能实现蜿蜒爬行、转向、抬头等多种运动方式．文中给出了该空间连杆机构的运动学解，基于Serpenoid曲线计算得到了实际控制所需的关节转角和步数，并编程实现了上述运动方式．     

基于控制函数的蛇形机器人攀爬运动分析

为实现对正交关节蛇形机器人多种运动形式的简单、统一控制,从研究蛇形机器人控制函数出发,提出了一种简单的并可同时实现正交关节蛇形机器人蜿蜒运动、行波运动、侧向翻滚运动和螺旋攀爬运动等多种运动形式的控制函数.对蛇形机器人实现螺旋攀爬运动的控制参数进行了分析,并用粒子群优化算法(PSO)对控制参数进行了优化拟合,给出了控制参...     

仿蛇变体机器人运动机理研究

本文设计了一种蛇形机器人，分析了蛇形机器人的结构，详细讨论了蛇形机器人的运 动机理和几何结构关系，并推导出蛇形机器人的控制算法和相应的控制程序，蛇形机器人在 程序控制下能够向前、向后运动，在一定程度上实现了蛇的运动．     

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。     

欠驱动两足步行机器人侧向稳定控制方法研究

以欠驱动两足步行机器人为对象研究其侧向运动稳定控制问题。首先分析引起机器人侧向运动不稳定的原因,然后提出步宽控制和侧向力矩补偿两种控制策略。步宽控制通过控制机器人侧向落脚位置,使其侧向运动周期与前向周期趋于一致实现侧向运动稳定。力矩补偿控制通过在踝关节引入侧向控制力矩,使侧向运动与前向运动协调一致实现侧向运动稳定。仿真实验表明,机器人实现了稳定的3D动态行走,达到了预期的控制效果。     

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.     

AmphiBot I: an amphibious snake-like robot

This article presents a project that aims at constructing a biologically inspired amphibious snake-like robot. The robot is designed to be capable of anguilliform swimming like sea-snakes and lampreys in water and lateral undulatory locomotion like a snake on ground. Both the structure and the controller of the robot are inspired by elongate vertebrates. In particular, the locomotion of the robot is controlled by a central pattern generator (a system of coupled oscillators) that produces travelling waves of oscillations as limit cycle behavior. We present the design considerations behind the robot and its controller. Experiments are carried out to identify the types of travelling waves that optimize speed during lateral undulatory locomotion on ground. In particular, the optimal frequency, amplitude and wavelength are thus identified when the robot is crawling on a particular surface.     

Development of a separable search-and-rescue robot composed of a mobile robot and a snake robot

Abstract

In this study, we propose a new robot system consisting of a mobile robot and a snake robot. The system works not only as a mobile manipulator but also as a multi-agent system by using the snake robot's ability to separate from the mobile robot. Initially, the snake robot is mounted on the mobile robot in the carrying mode. When an operator uses the snake robot as a manipulator, the robot changes to the manipulator mode. The operator can detach the snake robot from the mobile robot and command the snake robot to conduct lateral rolling motions. In this paper, we present the details of our robot and its performance in the World Robot Summit.     

SnakeSIM: a ROS-based control and simulation framework for perception-driven obstacle-aided locomotion of snake robots

Biological snakes are capable of exploiting roughness in the terrain for locomotion. This feature allows them to adapt to different types of environments. Snake robots that can mimic this behaviour could be fitted with sensors and used for transporting tools to hazardous or confined areas that other robots and humans are unable to access. Snake robot locomotion in a cluttered environment where the snake robot utilises a sensory–perceptual system to perceive the surrounding operational environment for means of propulsion can be defined as perception-driven obstacle-aided locomotion (POAL). The initial testing of new control methods for POAL in a physical environment using a real snake robot imposes challenging requirements on both the robot and the test environment in terms of robustness and predictability. This paper introduces SnakeSIM, a virtual rapid-prototyping framework that allows researchers for the design and simulation of POAL more safely, rapidly and efficiently. SnakeSIM is based on the robot operating system (ROS) and it allows for simulating the snake robot model in a virtual environment cluttered with obstacles. The simulated robot can be equipped with different sensors. Tactile perception can be achieved using contact sensors to retrieve forces, torques, contact positions and contact normals. A depth camera can be attached to the snake robot head for visual perception purposes. Furthermore, SnakeSIM allows for exploiting the large variety of robotics sensors that are supported by ROS. The framework can be transparently integrated with a real robot. To demonstrate the potential of SnakeSIM, a possible control approach for POAL is considered as a case study.     

基于ROS的蛇形机器人基本仿生运动与自主爬台阶控制

设计了一种带正交关节和主动轮组合的蛇形机器人。该机器人不仅能够实现基本的蜿蜒运动、纵向行波运动、横向翻滚运动和横向行波运动,且针对台阶式障碍物提出了一种自主爬越台阶的控制策略。机器人通过激光测距传感器与头部关节的仰角得到台阶高度,抬起相应高度的关节将头关节搭在台阶上,控制主动轮的推进速度与关节抬起的角速度相结合的方式达到上台阶的目的,并且在运动过程中将头部俯仰关节舵机的负载反馈作为判别下台阶的条件。基于ROS （robot operating system）构建了蛇形机器人仿真模型,并通过仿真与实验验证了机器人的基本运动控制和自主爬台阶控制策略的有效性。     

蛇形机器人控制系统的设计与实现

以蛇为模型的蛇形机器人的研究，扩大了机器人的应用领域．本文基于CAN总线技术完成了蛇形机器人控制系统的设计及研制，有效地实现了机器人的运动控制．在此基础上完成了蛇形机器人的集中式控制和分布式控制方式．     

3-D Snake Robot Motion: Nonsmooth Modeling, Simulations, and Experiments

A nonsmooth (hybrid) 3-D mathematical model of a snake robot (without wheels) is developed and experimentally validated in this paper. The model is based on the framework of nonsmooth dynamics and convex analysis that allows us to easily and systematically incorporate unilateral contact forces (i.e., between the snake robot and the ground surface) and friction forces based on Coulomb's law of dry friction. Conventional numerical solvers cannot be employed directly due to set-valued force laws and possible instantaneous velocity changes. Therefore, we show how to implement the model for numerical treatment with a numerical integrator called the time-stepping method. This method helps to avoid explicit changes between equations during simulation even though the system is hybrid. Simulation results for the serpentine motion pattern lateral undulation and sidewinding are presented. In addition, experiments are performed with the snake robot ldquoAikordquo for locomotion by lateral undulation and sidewinding, both with isotropic friction. For these cases, back-to-back comparisons between numerical results and experimental results are given.     

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.     

Control of snake robots with switching constraints: trajectory tracking with moving obstacle

We propose control of a snake robot that can switch lifting parts dynamically according to kinematics. Snakes lift parts of their body and dynamically switch lifting parts during locomotion: e.g. sinus-lifting and sidewinding motions. These characteristic types of snake locomotion are used for rapid and efficient movement across a sandy surface. However, optimal motion of a robot would not necessarily be the same as that of a real snake as the features of a robot’s body are different from those of a real snake. We derived a mathematical model and designed a controller for the three-dimensional motion of a snake robot on a two-dimensional plane. Our aim was to accomplish effective locomotion by selecting parts of the body to be lifted and parts to remain in contact with the ground. We derived the kinematic model with switching constraints by introducing a discrete mode number. Next, we proposed a control strategy for trajectory tracking with switching constraints to decrease cost function, and to satisfy the conditions of static stability. In this paper, we introduced a cost function related to avoidance of the singularity and the moving obstacle. Simulations and experiments demonstrated the effectiveness of the proposed controller and switching constraints.     

Obstacle avoidance of snake robot by switching control constraint

In this paper, we propose an obstacle avoidance method for autonomous locomotion control of a snake robot. The snake robot consists of rigid links, active joints and passive wheels, and can move only by varying its shape. The pass planning for the obstacle avoidance is a complicated problem because the snake robot has many states, control inputs and the under-actuated property. In our proposed method, the snake motion is restricted to a periodic undulate curve (called a serpenoid curve) by an additional control constraint and the undulate curve is tuned by switching the control constraint in order that the snake robot avoids the obstacle. Therefore, the path planning is simplified and the snake robot will achieve the obstacle avoidance with an efficient path. In this paper, we denote the details of our method and investigate the effectiveness of our strategy by numerical simulations.