管道机器人研究及样机开发

本文对管道机器人的各种行走方式进行了研究、分析和比较,着重讨论了轮式行走机构,并根据其轮子的配置方式进一步分为空间轮式、平面轮式和直线轮式,就其受力及运动特性进行了深入的分析、比较。     

全方位移动机器人结构和运动分析

全方位移动机器人具有平面运动的全部3个自由度，机动性好．本文介绍了全方位移动机器人的几种典型结构，进行了运动学分析．最后介绍了我们所研制的全方位移动机器人．     

在球面运行的万向轮式移动机器人运动学模型的建立

爬壁机器人技术的不断发展,使研制可以吸附在大 型球面工作的轮式移动机器人成为可能．本文采用坐标变换方法,针对工作在球面的万向轮 式移动机器人建立运动学模型．其建模方法对于其它类型的在球面工作的轮式移动机器人也 同样适用．     

四轮全方位移动机器人各向相异性研究

由于全方位轮的特殊构造，使得全方位移动机器人沿不同方向运动时具有的最大速度不同，以及在不同方向上的加速性能也不同，称之为各向相异性（anisotropy）．为了充分发挥全方位移动机器人的优越性，通过对4轮全方位移动机器人进行运动学、动力学建模，分析了机器人各向相异性，确定了轮系布置与最大速度曲线的相关规律，以及当机器人沿某一方向以一定加速度运动时，不同轮子上驱动电机所需提供的转矩，从而使得机器人加速运动时更好地避免轮子打滑．并且通过Matlab-ADAMS联合仿真以及实际实验，验证了分析结果的正确性．对机器人的各向相异性作了全面系统的研究，从而更清楚地表述了模型特性，为更好地控制全方位移动机器人提供了基础．     

具有MY轮的全方位移动机器人运动学研究

根据MY轮的结构特点建立了由MY轮组成的全方位移动机器人的运动学模型.分析了由于轮结构带来的运动学特性.对全方位移动机器人在运动过程中的振动、控制及误差进行了深入研究.提出了通过优化接触距离及MY轮转速来减小机器人运动误差的控制方法.为获得优化结构,比较了三轮结构和四轮结构的运动学特性.同时应用正弦控制规律来合理控制MY轮的转动,改善了机器人的运动稳定性.仿真结果充分证明了分析的正确性.     

基于阿克曼原理的车式移动机器人运动学建模

基于阿克曼原理的轮式移动机器人运动学模型对于无人驾驶车辆的研究有着重要的意义.对轮式移动机器人的运动学特性进行了分析,建立了不考虑滑行、刹车等的轮式移动机器人的运动学模型.对该运动学模型引入了阿克曼约束,给出了描述机器人运动状态的转向角、航向角和转弯半径等物理量的数学公式.最后对该运动学模型进行仿真实验,验证了所建立的运动学模型的正确性,为进一步研究轮式移动机器人提供了理论分析的基础.     

一种全方位移动机器人

研制了一种新型全方位轮式移动机器人,该机器人主要由三个特殊的轮式结构—MY轮组成.MY轮利用球体的运动原理,将球体分为接触区和非接触区,利用两球体的接触区与非接触区的相互补充实现了万向轮的功能.两部分球体的被动旋转轴成45度交叉布置,实现了与地面的连续接触;同时该结构也增加了万向轮的强度.对轮式移动机构的运动学分析和仿真证明了该机构能够实现全方位移动.机器人的运动实验也证明了该万向轮机构不仅能够实现全方位运动,而且还能够跨越障碍物.     

电动并联六轮足机器人的运动驱动与多模态控制方法

提出一种并联六轮足移动机器人．该机器人设有多模式Stewart型腿结构,其负载能力大,集成了轮式运动和足式运动的优点,可实现足式、轮式、轮足复合式运动．首先,阐述了机器人设计思路,对电动并联六轮足机器人的硬件系统和控制系统进行设计．其次,针对足式运动模式,设计了一套完整的足式“三角”步态和稳定行走算法,该算法可降低足端与地面之间的垂直方向冲击,防止足式运动拖腿或打滑;针对轮式运动模式,设计并介绍了6轮协同控制和轮式协同转向原理;针对轮足复合式运动模式,介绍了变高度、变支撑面、变轮距、主动隔振控制原理,重点分析了主动隔振控制和变轮距控制,可实现主动隔振及姿态平稳控制,提高了机器人在崎岖颠簸地形下的轮足复合式运动的稳定性．最后,对电动并联六轮足机器人的足式、轮式、轮足复合式运动模式进行实验,实验结果验证了本文提出的并联六轮足移动机器人设计的可行性和各运动模式下驱动与控制算法的有效性．     

非完整轮试移动机器人的轨迹跟踪滑模控制

由于轮式移动机器人的非完整性质和运动受限性质,它的轨迹跟踪已经成为一类具有挑战性的控制问题.针对一个可以在医院环境中执行护理任务的室内移动机器人-护士助手机器人,提出一种轮式移动机器人的轨迹跟踪滑模控制方法.由移动机器人在极坐标系中的运动学方程出发设计一个滑模控制器,进而提出了一种新的滑模控制方法,解决了在极坐标系中关于运动学的跟踪问题.分析了此方法的稳定性和执行性能,并且通过仿真证明这个控制方法的实际应用的有效性.     

基于动力学模型的轮式移动机器人电机控制

针对移动机器人两路电机协同控制问题,提出基于动力学模型的轮式移动机器人电机控制律 （DMMC）．首先推导出质心位置不一定在几何中心的移动机器人运动学模型和动力学模型,并求解出两轮速 度与力矩之间的非线性微分方程．然后,基于两轮速度与力矩间非线性微分方程、电机电气方程和电机机电 方程,推导出移动机器人系统状态方程．最后采用极点配置得到I 型状态反馈控制律．仿真显示,DMMC 法实 现了对输入指令的零稳态误差快速响应．     

Kinematic modeling of wheeled mobile robots

We formulate the kinematic equations of motion of wheeled mobile robots incorporating conventional, omnidirectional, and ball wheels.¹ We extend the kinematic modeling of stationary manipulators to accommodate such special characteristics of wheeled mobile robots as multiple closed-link chains, higher-pair contact points between a wheel and a surface, and unactuated and unsensed wheel degrees of freedom. We apply the Sheth-Uicker convention to assign coordinate axes and develop a matrix coordinate transformation algebra to derive the equations of motion. We introduce a wheel Jacobian matrix to relate the motions of each wheel to the motions of the robot. We then combine the individual wheel equations to obtain the composite robot equation of motion. We interpret the properties of the composite robot equation to characterize the mobility of a wheeled mobile robot according to a mobility characterization tree. Similarly, we apply actuation and sensing characterization trees to delineate the robot motions producible by the wheel actuators and discernible by the wheel sensors, respectively. We calculate the sensed forward and actuated inverse solutions and interpret the physical conditions which guarantee their existence. To illustrate the development, we formulate and interpret the kinematic equations of motion of Uranus, a wheeled mobile robot being constructed in the CMU Mobile Robot Laboratory.     

Kinematic modeling of wheeled mobile robots with slip

This work presents a kinematic modeling method for wheeled mobile robots with slip based on physical principles. First, we present the kinematic modeling of a mobile robot with no-slip considering four types of wheels: fixed, centered orientable, off-centered orientable (castor) and Swedish (also called Mecanum, Ilon or universal). Then, the dynamics of a wheeled mobile robot based on Lagrange formulation are derived and discussed. Next, a quasi-static motion is considered to obtain the kinematic conditions that provide the slip modeling equations. Several types of traction models for the slip between the wheel and the floor are indicated. In particular, for a frictional force linearly dependent on the sliding velocity, the no-slip kinematic equation of the wheeled mobile robot is related, through the weighted least-squares algorithm, with the slip modeling equations. To illustrate the applications of the proposed approach a tricycle vehicle is considered in a real situation. The experimental results obtained for the slip kinematic model are compared with the ones obtained for the well-known Kalman filter.     

Kinematic modeling and singularity of wheeled mobile robots

This paper presents a global singularity analysis for wheeled mobile robots (WMRs). First, a kinematic model of a generic wheel is obtained using a recursive kinematics formulation. This novel and efficient approach is valid for all the common types of wheels: fixed, centered orientable, off-centered orientable (caster or castor) and Swedish or Mecanum. Then, a procedure for generating robot kinematic models is presented based on the set of wheel equations and the null space concept. Next, the singularity of kinematic models is discussed: first, the kinematic singularity condition in forward models is obtained, and then the singularity condition in inverse, or even mixed, models. A generic and practical geometric approach is established to characterize the singularity of any kinematic model of any WMR with the mentioned wheels. To illustrate the applications of the proposed approach, the singular configurations for many types of WMRs are depicted. Finally, the singularity characterization is extended to include other specialized wheels: dual-wheel, dual-wheel castor, ball-type and orthogonal.     

存在滑移和侧滑的轮式移动机器人轨迹跟踪

轮式移动机器人由于存在非完整性约束,其轨迹跟踪有一定挑战性.实际机器人运动中由于轮胎变形或其他原因,往往存在侧滑和滑移,对存在滑移的轮式移动机器人进行了研究,对其建立运动学模型,对存在滑移的轮式移动机器人的轨迹跟踪进行研究.基于Iyapunov函数,提出了轨迹跟踪控制算法,最后使用Matlab进行仿真,证明该控制算法具有快速,精确,全局稳定的良好特性.     

Attitude-based dynamic and kinematic models for wheels of mobile robot on deformable slope

Deformable slope is a type of terrain that wheeled mobile robots (WMRs) and ground unmanned vehicles (GUVs) may have to traverse to accomplish their mission tasks. However, the associated terramechanics for wheels with arbitrary posture is rarely studied. In this paper, based on wheel attitude, dynamics of the wheel–terrain interaction for a rigid wheel on deformable slope is investigated. Through introducing the angular geometry of wheel attitude into terramechanics theory, a generalized dynamic model is developed, involving two inclination angles of slope and three attitude angles of wheel steering axis. Two representative cases are studied: the wheel runs straight forward and perpendicular to the slope, and the wheel is in a steering maneuver with an inclined steering axis. A generalized kinematic model for wheel–terrain contact point and wheel center is also provided, which analytically explicates that trajectory of wheel motion is coupled with wheel attitude while driven by angular rates. The proposed attitude-based models are valid for arbitrary wheel–terrain geometry and can lead to control purpose directly. Effectiveness of the models is confirmed by simulating the influences from attitude to wheel mechanics and motion.     

A model-based fault diagnosis scheme for wheeled mobile robots

In this paper, a fault diagnosis scheme for wheeled mobile robots is presented. In the fault detection module, a nonlinear observer is designed based on the mobile robot dynamic model. A fault is detected when at least one of the residuals exceeds its corresponding threshold. After the fault is detected, the fault isolation module is activated to isolate three types of fault: right wheel fault, left wheel fault, and other changing dynamic parameter faults. Three simulation examples are performed to show the effect of each fault to the tracking performance of mobile robot in a real situation. The simulation results demonstrate the effectiveness of our proposed approach for fault detection and isolation in wheeled mobile robots.     

移动机器人滑动参数定界及鲁棒镇定控制

本文针对带运动学参数不确定性的野外轮式移动机器人模型的在线辨识、定界和点镇定控制问题展开了研究.考虑了移动机器人二维平面运动过程中所存在的滑动效应和自身几何参数未知等不确定性,并将其建模为运动学模型中所包含的未知时变参数.通过引入基于有界误差假设的非线性集员滤波方法,对移动机器人运动学模型中存在的不确定性参数进行了辨识和定界.在此基础上结合backstepping控制思想和Lyapunov分析方法解决了移动机器人的鲁棒镇定问题,在存在滑动参数干扰的情况下实现了移动机器人的全局指数收敛点镇定控制,提高了整体控制系统的稳定性和鲁棒性.仿真结果证明了本方法的有效性和鲁棒性.     

Switched Modeling and Task–Priority Motion Planning of Wheeled Mobile Robots Subject to Slipping

This study is devoted to the modelling and control of Wheeled Mobile Robots moving with longitudinal and lateral slips of all wheels. Due to wheel slippage we have to deal with systems with changing dynamics. Wheeled Mobile Robots can be thus modeled as switched systems with both autonomous switches (due to wheel slippage) and smooth controls (due to control algorithm). It is assumed that the slipping is counteracted by the slip reaction forces acting at contact points of the wheels with the ground. A model of these reaction forces, borrowed from the theory of automotive systems, has been adopted and included into the Lagrangian dynamic equations of the robot. A framework for designing motion planning schemes devoid of chattering effects for systems with changing dynamics is presented. A task–priority motion planning problem for wheeled mobile robots subject to slipping is addressed and solved by means of Jacobian motion planning algorithm based on the Endogenous Configuration Space Approach. Performance of the algorithm is presented in simulations of the Pioneer 2DX mobile platform. The robot dynamics equations are derived and 4 variants of motion are distinguished. The motion planning problem is composed of two sub-tasks: robot has to reach a desired point in the task space (proper motion planning) and the motion should minimize either the control energy expendinture or the wheel slippage. Performance of the motion planning algorithm is illustrated by a sort of the parking maneuver problem.     

基于神经网络的不确定移动机器人鲁棒自适应跟踪控制

针对含运动学未知参数以及动力学模型不确定的非完整轮式移动机器人轨迹跟踪问题,基于Radical Basis Function（径向基函数）神经网络,提出了一种鲁棒自适应控制器.首先,考虑移动机器人运动学参数未知的情况,提出了一种含自适应参数的运动学控制器,用以补偿参数不确定性导致的系统误差;其次,利用神经网络控制技术,对于机器人在移动中动力学模型不确定问题,提出了一种具有鲁棒性的动力学控制器,使得移动机器人可以在不知道具体动力学模型的情况下跟踪到目标轨迹;最后利用Lyapunov稳定性理论证明了整个系统的稳定性.通过数值仿真验证了所设计的控制器的可行性.     

Control of wheel system under uncertainty

Consideration was given to the nonholonomic mechanical systems with rolling or the wheel systems such as mobile robot, car, or wheeled tractor. Analysis was confined to the kinematic models with regard for the dynamics of the controlling drives. Control of system motion along a given trajectory (planar smooth curve) was studied. The designed control law stabilizes this motion in large in the basic variables. The main result lies in solution of the problem of control under uncertainty when only sufficiently general dynamic characteristics of the wheel system drive are known.