爬壁机器人全方位移动机构的研究

所谓全方位移动机构，它是由Ｎ个（Ｎ≥３）定向滑移轮组成的车体，无需绕垂直于车辆平面的轴作任何转动，仅造轮子的转向与转速的不同组全，便可实现沿任意方向直线前进的功能，并能在原地旋转任意角度，这种机构在爬壁机器人上使用有其突出优点，运动灵活，能行走到任意位置，本文对全方位移动机构进行研究及设计。     

轮式移动机器人在圆形管道中的运动学建模与分析

为解决圆形管道中轮式移动机器人的运动控制问题,分析了轮式移动机器人在圆形管道中的运动学特性．借助接触点的切平面,单个轮子在平面上的位置和运动描述方法被应用在圆管的柱面上．推导了单个轮子在柱面上纯滚动时轮心的轨迹和速度．运用刚体运动瞬时螺旋理论,对由两个固定轮和一个舵轮组成的(1,1)型三轮机器人在圆形管道中的运动进行了建模分析,并对此运动学模型进行了仿真．     

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.     

四轮全方位移动机器人的建模和最优控制

本文研究实时动态环境中四轮全方位移动机器人的运动控制和轨迹规划.通过对机器人运动学和动力学特性的分析,给出了四轮全方位移动机器人的控制模型,并根据方程特性对其进行了合理的简化,使得计算量有效减少.同时采用Bang-Bang控制规划出时间最优的机器人运动轨迹.通过轨迹规划和控制模型的结合达到了实时控制的效果.实验证明了模型的正确性和算法的有效性.     

一种基于拟全方位视觉的移动机器人自运动融合估计方法

基于地平面假设的移动机器人单路视觉运动估计存在鲁棒性和环境适应性较差、精度较低等缺 点,针对这一问题,本文首先介绍了拟全方位视觉系统的构成,并结合该视觉系统的特点给出了一种基于两 步运动的摄像头平行位姿参数标定方法．然后据此提出了一种基于拟全方位视觉的自主移动机器人自运动融 合估计方法．该方法能够借助机器人的非完整运动约束、地平面运行假设以及运动估计参数之间的相容性测 度等多种因素,对拟全方位视觉系统中的各路视觉估计进行性能综合评价;最终依据评价结果融合确定出具 有较高可信度和较强鲁棒性的运动估计参数．实验结果从鲁棒性、精度以及实时性等方面验证了本算法的有 效性．     

基于模糊神经网络的移动机器人沿墙导航控制

移动机器人沿墙导航控制包含了追踪和避障两种情况,是移动机器人研究中的常见问题。它是指机器人在一定方向上沿墙运动,或者更一般意义上的沿着物体轮廓运动,并与墙保持一定距离。移动机器人利用声纳采集机器人与墙体的距离和角度信息,通过模糊神经网络将输入数据进行融合,从而判断移动机器人的位姿信息,输出左右轮速度控制其动作。实验证明此方法可以有效地保证移动机器人在安全距离内沿墙体运动。对比采用模糊神经网络前后的实验,采用后的移动机器人沿墙导航控制轨迹优于采用前,均方误差大大减小。     

一类全方位移动机器人的不确定扰动数学模型

本文针对一类正交轮全方位移动机器人的机构特点，分析了运行中由于其结构因素引起机器人运动不稳定的主要原因．针对此类结构运动过程存在的不确定扰动问题，分析了它的产生机理及其变化规律，并推导出在该种不确定性扰动影响下的移动机器人动力学模型．该模型可为正交轮全方位移动机器人运动控制提供理论依据，具有较强的理论意义和应用价值．     

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.     

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．     

三轮全方位移动机器人运动模型及其控制方法研究

全方位移动机器人在二维空间具有完整性约束条件,能够灵活地任意方向移动,受到了广泛的关注。针对三轮全方位机器人的运动控制问题,建立其运动学模型。采用输入变换解耦及状态反馈法实现对坐标位置、方位角等位姿状态的控制,通过仿真实验验证了算法的有效性。最后给出了一种三轮全方位移动机器人硬件设计方案及控制算法软件实现,实际样机运动实验验证了控制方法的可行性与有效性。     

Design and Control of a Four‐Wheeled Omnidirectional Mobile Robot with Steerable Omnidirectional Wheels

Omnidirectional mobile robots are capable of arbitrary motion in an arbitrary direction without changing the direction of wheels, because they can perform 3 degree‐of‐freedom (DOF) motion on a two‐dimensional plane. In this research, a new class of omnidirectional mobile robot is proposed. Since it has synchronously steerable omnidirectional wheels, it is called an omnidirectional mobile robot with steerable omnidirectional wheels (OMR‐SOW). It has 3 DOFs in motion and one DOF in steering. One steering DOF can function as a continuously variable transmission (CVT). CVT of the OMR‐SOW increases the range of velocity ratio from the wheel velocities to robot velocity, which may improve performance of the mobile robot. The OMR‐SOW with four omnidirectional wheels has been developed in this research. Kinematics and dynamics of this robot will be analyzed in detail. Various tests have been conducted to demonstrate the validity and feasibility of the proposed mechanism and control algorithm. © 2004 Wiley Periodicals, Inc.     

Dynamic Model and Control for a Holonomic Omnidirectional Mobile Robot

In the recent past, mobile robots with high mobility have been developed actively. We have already proposed a holonomic and omnidirectional mobile robot using two active dual-wheel caster assemblies and also derived the kinematic models for the assembly and the mobile robot. This paper presents dynamic analysis and control for the mobile robot. The dynamic model has been derived based on the forces acting on the steering axis. Then a model-based resolved acceleration controller is constructed. The validity of the model and the effectiveness of the control system are confirmed by experiments using a prototype robot as well as simulations.     

The kinematics for redundantly actuated omnidirectional mobile robots

Omnidirectional mobile robots have been popularly employed in several application areas. However, the kinematics and singularity analysis for these systems have not been clearly identified, especially for the redundantly actuated case, which is common in current omnidirectional mobile robots. In light of this fact, this article introduces two different kinematic approaches for a typical omnidirectional mobile robot having three caster wheels, and examines singularity configurations of such systems. Then, a singularity‐free load‐distribution scheme for a redundantly actuated three‐wheeled omnidirectional mobile robot is proposed. Through simulation, several advantages of the redundantly actuated mobile robot (singularity avoidance, input‐load saving, and exploiting several subtasks) are presented. © 2002 Wiley Periodicals, Inc.     

Robust and real-time self-localization based on omnidirectional vision for soccer robots

Self-localization is the basis to realize autonomous ability such as motion planning and decision-making for mobile robots, and omnidirectional vision is one of the most important sensors for RoboCup Middle Size League (MSL) soccer robots. According to the characteristic that RoboCup competition is highly dynamic and the deficiency of the current self-localization methods, a robust and real-time self-localization algorithm based on omnidirectional vision is proposed for MSL soccer robots. Monte Carlo localization and matching optimization localization, two most popular approaches used in MSL, are combined in our algorithm. The advantages of these two approaches are maintained, while the disadvantages are avoided. A camera parameters auto-adjusting method based on image entropy is also integrated to adapt the output of omnidirectional vision to dynamic lighting conditions. The experimental results show that global localization can be realized effectively while highly accurate localization is achieved in real-time, and robot self-localization is robust to the highly dynamic environment with occlusions and changing lighting conditions.     

INTELLIGENT MOTION CONTROL FOR OMNIDIRECTIONAL MOBILE ROBOTS USING ANT COLONY OPTIMIZATION

This article presents an intelligent system-on-a-programmable-chip-based (SoPC) ant colony optimization (ACO) motion controller for embedded omnidirectional mobile robots with three independent driving wheels equally spaced at 120 degrees from one another. Both ACO parameter autotuner and kinematic motion controller are integrated in one field-programmable gate array (FPGA) chip to efficiently construct an experimental mobile robot. The optimal parameters of the motion controller are obtained by minimizing the performance index using the proposed SoPC-based ACO computing method. These optimal parameters are then employed in the ACO-based embedded kinematic controller in order to obtain better performance for omnidirectional mobile robots to achieve trajectory tracking and stabilization. Experimental results are conducted to show the effectiveness and merit of the proposed intelligent ACO-based embedded controller for omnidirectional mobile robots. These results indicate that the proposed ACO-based embedded optimal controller outperforms the nonoptimal controllers and the conventional genetic algorithm (GA) optimal controllers.     

基于模糊自适应控制的全向移动机器人的运动控制研究

由于四轮驱动全向移动机器人轮系分布的特点,四轮之间存在耦合关系,在运行过程中,机器人整体运动的稳定性及控制精度都不佳。针对此问题,本文设计一种基于模糊自适应控制器的误差修正方法,结合模糊控制和PD控制,在线对机器人体进行误差修正,并将整体误差按轮系结构分布合理分配到单个轮子上,从而将整体的误差修正转化为单个轮子的误差修正。通过在Matlab-Simulink环境下仿真实验表明,在使用模糊自适应控制器进行误差修正后,机器人对线速度及角速度的跟随性明显提高,改善了机器人运动控制的精度。     

Holonomy in mobile robots

The search for a simple and accurate odometry is a main concern when working with mobile robots. This article presents a general analysis of the problem and proposes a particular solution to improve the odometry. The three crucial kinematical aspects of mobile robots (mobility, control, and positioning) are reviewed in detail for vehicles based both in conventional and in omnidirectional wheels. The latter case is more suitable from a maneuvering point of view as it provides the robot frame with the three Degrees Of Freedom (DOF) of plane motion without singular configurations. Moreover, a suitable design of the omnidirectional wheels leads to a strictly invariant Jacobian matrix and thus to a linear control equation with constant coefficients. It is shown that such vehicles may have a holonomic behavior when moving under suitable kinematical restrictions without constraining their trajectory. In that case, the odometry is algebraic (instead of integrative) and thus more accurate. An application case is presented.     

Design,Development, and Mobility Evaluation of an Omnidirectional Mobile Robot for Rough Terrain

Omnidirectional vehicles have been widely applied in several areas, but most of them are designed for the case of motion on flat, smooth terrain, and are not feasible for outdoor usage. This paper presents the design and development of an omnidirectional mobile robot that possesses high mobility in rough terrain. The omnidirectional robot consists of a main body with four sets of mobility modules, called an active split offset caster (ASOC). The ASOC module has independently driven dual wheels that produce arbitrary planar translational velocity, enabling the robot to achieve its omnidirectional motion. Each module is connected to the main body via a parallel link with shock absorbers, allowing the robot to conform to uneven terrain. In this paper, the design and development of the ASOC‐driven omnidirectional mobile robot for rough terrain are described. A control scheme that considers the kinematics of the omnidirectional mobile robot is presented. The mobility of the robot is also evaluated experimentally based on a metric called the ASOC mobility index. The mobility evaluation test clarifies a design tradeoff between terrain adaptability and omnidirectional mobility due to the shock absorbers. In addition, an odometry improvement technique that can reduce position estimation error due to wheel slippage is proposed. Experimental odometry tests confirmed that the proposed technique is able to improve the odometry accuracy for sharp‐turning maneuvers.     

Independent traction control for uneven terrain using stick-slip phenomenon: application to a stair climbing robot

Mobile robots are being developed for building inspection and security, military reconnaissance, and planetary exploration. In such applications, the robot is expected to encounter rough terrain. In rough terrain, it is important for mobile robots to maintain adequate traction as excessive wheel slip causes the robot to lose mobility or even be trapped. This paper proposes a traction control algorithm that can be independently implemented to each wheel without requiring extra sensors and devices compared with standard velocity control methods. The algorithm estimates the stick-slip of the wheels based on estimation of angular acceleration. Thus, the traction force induced by torque of wheel converses between the maximum static friction and kinetic friction. Simulations and experiments are performed to validate the algorithm. The proposed traction control algorithm yielded a 40.5% reduction of total slip distance and 25.6% reduction of power consumption compared with the standard velocity control method. Furthermore, the algorithm does not require a complex wheel-soil interaction model or optimization of robot kinematics.