Receding horizon tracking control for wheeled mobile robots with time-delay

In this paper, a receding horizon (RH) controller is developed for tracking control of wheeled mobile robots (WMRs) subject to nonholonomic constraint in the environments without obstacles. The problem is simplified by neglecting the vehicle dynamics and considering only the steering system. First, the tracking-error kinematic model is linearized at the equilibrium point. And then, it is transferred to an exact discrete form considering the time-delay. The control policy is derived from the optimization of a quadratic cost function, which penalizes the tracking error and control variables in each sampling time. The minimizing problem is solved by using the QP (quadratic programming) method taking the current error state as the initial value and including the velocity constraints. The performance of the control algorithm is verified via the computer simulations with several different predefined trajectories showing that the strategy is feasible. This paper was recommended for publication in revised form by Associate Editor Doo Yong Lee Kil To Chong (M’96) received the Ph.D. degree in mechanical engineering from Texas A&M University, College Station, in 1995. Currently, he is a Professor at the School of Electronics and Information Engineering, Chonbuk National University, Jeonju, Korea, and Head of the Mechatronics Research Center granted from the Korea Science Foundation. His research interests are in the areas of motor fault detection, network system control, time-delay systems, and neural networks. Chang Goo Lee was born in Chonju, South Korea on Dec., 1958. He received the B.S. and M.S., and Dr.Eng. degrees in Electrical Engineering from Chonbuk National University, South Korea, 1981, 1983 and 1990 respectively. He had been with ETRI as a senior researcher from 1983 to 1991. Since 1992, He has been with the School of Electronic and Information Engineering, Chonbuk National University where he is presently a Professor. His research interests include intelligent control, nonlinear control, and home network control. Yu Gao received the master’s degree in Electronics and Information from Chonbuk National University, Korea, in 2008. He got his bachelor’s degree in Physics from Soochow University, China, in 2005. Currently, he is a Ph.D. candidate in the School of Electronics and Information, Chonbuk National University, Korea. His research interests are in the area of the receding horizon control.     

Research on algorithm of wheeled mobile robot's trajectory tracking control

为解决轮式移动机器人平面运动控制问题,将平面几何理论应用于轨迹跟踪控制中.建立了机器人平面运动模型,并以此为基础研究了直线和圆弧的轨迹跟踪控制算法;提出了导航圆方法,将机器人实时位置信息和目标轨迹之间的角度偏差及位置偏差综合成一个角度,然后对该角度进行了PID调节;在实验中,将直线、圆弧轨迹跟踪算法实际运用于机器人的运动控制.研究结果表明,该算法能将机器人轨迹的偏差有效地控制在±1 cm以内.     

轮式移动机器人的模糊轨迹跟踪控制

文章针对实际的轮式移动机器人轨迹跟踪控制问题提出了一种解决方法。利用模糊控制器实现对移动机器人的轨迹控制,并进行了计算机仿真和实际的轮式移动机器人的轨迹控制实验,将控制效果与传统的PID控制器的控制结果进行比较,结果表明了模糊控制在机器人轨迹跟踪问题上具有很好的性能。     

模糊控制在移动机器人路径跟踪控制中的应用

对含不确定性的移动机器人系统设计了自适应模糊路径跟踪控制方法,此方法采用模糊逻辑系统逼近控制器中的不确定函数,基于时变死区函数对模糊逻辑系统中的未知参数进行自适应调节,并对时变死区设计了自适应律。文中证明了此方法可使跟踪误差收敛到原点的小邻域内。仿真算例验证了此方法的有效性。     

Kinematics of wheeled mobile robots on uneven terrain

This paper deals with the kinematic analysis of a wheeled mobile robot (WMR) moving on uneven terrain. It is known in literature that a wheeled mobile robot, with a fixed length axle and wheels modeled as thin disk, will undergo slip when it negotiates an uneven terrain. To overcome slip, variable length axle (VLA) has been proposed in literature. In this paper, we model the wheels as a torus and propose the use of a passive joint allowing a lateral degree of freedom. Furthermore, we model the mobile robot, instantaneously, as a hybrid-parallel mechanism with the wheel–ground contact described by differential equations which take into account the geometry of the wheel, the ground and the non-holonomic constraints of no slip. We present an algorithm to solve the direct and inverse kinematics problem of the hybrid-parallel mechanism involving numerical solution of a system of differential-algebraic equations. Simulation results show that the three-wheeled WMR with torus shaped wheels and passive joints can negotiate uneven terrain without slipping. Our proposed approach presents an alternative to variable length axle approach.     

移动机器人在线实时路径规划

研究了不确定环境下移动机器人的路径规划问题。采用全局规划和局部规划相结合的方法，提出了一种基于极坐标空间，以期望方向角为优化性能指标的在线实日寸路径规划方法。该法利用机器人的传感器系统，实时探测局部环境信息，在每次的局部规划窗口，确定机器人的期望方向角，以机器人的实际运动方向角与期望方向角之间的差异来驱动机器人避开障碍物和朝向目标点运动。该法不仅简单灵活，而且克服了全局规划和局部规划的缺陷。仿真实验表明其有效可行性、实时性、优化性、精度高、稳定性好。     

A path tracking control algorithm for underwater mining vehicles

In this paper, a path tracking control algorithm is formulated for the use of tracked underwater mining vehicles. The algorithm consists of two parts, the forward velocity control and the heading angle control. The control algorithm is designed based on kinematics, and it considers the track slips and the longitudinal and yaw dynamic models of the tracked vehicle including the soil-track interaction force model. The desired heading angle is obtained by the so-called “Line of Sight” method. The suggested algorithm is tested by numerical simulations using the TRACSIM software developed by MOERO/KORDI, Korea. After the control gains are tuned by a series of numerical simulations, the algorithm is verified on a scale vehicle on air on a soil bin test bed containing the cohesive soil of the Bentonite-water mixture. This paper was recommended for publication in revised form by Associate Editor Kyongsu Yi Sup Hong received the B.Sc. and the M.sc. degree in the department of naval architecture and ocean engineering from Seoul National University, Korea, and the Doctor of Engineering degree in mechanical engineering from the Technical university of Aachen, Germany. Currently, he is the principal researcher at MOERI (Maritime and Ocean Engineering Research Institute), Korea. His main research areas include dynamics of marine structure, and development of marine mineral resources. Especially, he is focusing on the development of deep seabed mining technologies since 1994. Mooncheol Won received the B.Sc. and the M.sc. degree in the department of naval architecture and ocean engineering from Seoul National University, Korea, and the Ph.D. degree in mechanical engineering from the University of California at Berkeley, USA. Currently, he is a professor in the department of mechatronics engineering of Chungnam national university, Korea. His research interests include control of maritime and mechatronics systems, and machine learning applications of robotic systems.     

Design, modelling and errors measurement of wheeled mobile robots

This paper presents the mechanical design process of an omni-directional mobile robot. In addition, the kinematics equations of the final design are derived, and the inverse Jacobian matrix of the robot is presented. The dynamic equations of motion for the final design are derived in a symbolic form, assuming that no slip occurs on the wheel in the spin direction. In order to validate the kinematics and dynamic equation, we carried out consequences of simulation using two pieces of software, Maple and Working Model. Finally, the mobile robot is moved in given trajectories and the systematic errors of the robot are determined. To overcome the problems, a new method was introduced in which the robot was programmed to move in the direction of each wheel shaft.     

移动机器人路径规划方法研究

本文介绍了几种路径规划方法的优缺点以及改进方法。针对人工势场法的不足提出改进算法,并对该方法进行仿真分析。展示利用模糊神经网络法避障实例,应用结果表明该方法可以有效地避开障碍物到达目标位置。     

障碍环境下轮式移动操作机随机路径规划方法

针对移动操作机系统的高度冗余性和受非完整约束的特点,将随机路径规划方法应用于移动操作机系统的避障路径规划,首先求出移动平台的一条满足非完整约束的简单路径,然后以此路径作为位置约束,以操作臂的位形空问为采样空间进行随机无碰路径规划,最终实现了移动操作机在满足路径规划约束条件下的无碰操作运动。最后以平面移动操作机为例,通过计算机仿真说明了该方法的有效性。     

考虑参数不确定性和外界干扰的移动机器人轨迹跟踪控制

针对具有参数不确定性和外界干扰的移动机器人轨迹跟踪问题,提出一种运动学跟踪控制器和动力学跟踪控制器相结合的控制方法。基于反演方法,应用自适应控制技术设计速度控制率的同时,对运动学模型中的未知参数进行了估计。在此基础上,引入动力学回归矩阵和单层神经网络以使机器人实际速度接近理论速度,并减弱系统参数不确定和外界干扰对于跟踪控制效果的影响。设计过程中,根据Lyapunov稳定性定律和Barbalat引理对控制系统的稳定性和收敛性进行了分析。对于典型曲线的仿真结果表明了所提出控制方法的有效性。     

一种差动轮式竞赛机器人的路径跟踪方法

两个编码器作为唯一的传感器对称地安装在差速轮式机器人的底盘上,通过采集编码器随机器人运动产生的脉冲可以换算出机器人的里程值。根据两个对称安装的编码器计算出机器人的实时角度,结合经典PID控制算法,对事先规划好的路径进行跟踪和准确停车定位。依据里程和角度进行直线跟踪和弧线跟踪就可以组成复杂的路径跟踪。测试结果表明控制方法简单实用,成本低,具有很好的使用价值。     

Sliding mode control of two-wheeled welding mobile robot for tracking smooth curved welding path

In this paper, a nonlinear controller based on sliding mode control is applied to a two-wheeled Welding Mobile Robot (WMR) to track a smooth curved welding path at a constant velocity of the welding point. The mobile robot is considered in terms of dynamics model in Cartesian coordinates under the presence of external disturbance, and its parameters are exactly known. It is assumed that the disturbance satisfies the matching condition with a known boundary. To obtain the controller, the tracking errors are defined, and the two sliding surfaces are chosen to guarantee that the errors converge to zero asymptotically. Two cases are to be considered : fixed torch and controllable torch. In addition, a simple way of measuring the errors is introduced using two potentiometers. The simulation and experiment on a two-wheeled welding mobile robot are provided to show the effectiveness of the proposed controller.     

全方位移动机器人编队控制研究

针对多机器人系统编队的控制问题,将编队行为分为了任务执行行为、队形保持行为、安全运行行为,并分别对各行为进行了研究,对各种传统编队方法进行了总结和比较,通过建立移动机器人的运动学模型,得到了车体运动的控制参数,提出了针对基于麦克纳姆轮的全方位移动机器人编队的基于行为的融合编队控制算法,利用Matlab软件对编队的各种行为进行了仿真。研究结果表明,该基于行为的融合编队控制算法能使全方位机器人完成编队行为,能够实现队形形成、队形保持、躲避静态障碍物、躲避机器人及驶向目标点等行为,编队基于该方法,实现迅速、可靠性高。     

基于改进直接模糊自适应反馈控制的多移动机器人编队算法

针对多移动机器人控制系统适应性差、控制精度低的问题,提出一种改进直接模糊自适应反馈控制方法.利用模糊数学理论分别对机器人的理想输入状态量进行逼近,通过模糊逻辑推理得到输出反馈量并实时调整状态量,应用Lyapunov理论保证系统误差的收敛性和系统的稳定性,最后在MATLAB中对所设计的WMR动力学和运动学相结合的控制系统...     

Adaptive tracking control of two-wheeled welding mobile robot with smooth curved welding path

This paper proposes an adaptive controller for partially known system and applies to a two-wheeled Welding Mobile Robot (WMR) to track a reference welding path at a constant velocity of the welding point. To design the tracking controller, the errors from WMR to steel wall is defined, and the controller is designed to drive the errors to zero as fast as desired. Additionally, a scheme of error measurement is implemented on the WMR to meet the need of the controller. In this paper, the system moments of inertia are considered to be partially unknown parameters which are estimated using update laws in adaptive control scheme. The simulations and experiments on a welding mobile robot show the effectiveness of the proposed controller.     

轮式移动机器人遥控系统控制方案设计

本文试结合轮式移动机器人论述了一种轮式移动机器人遥控系统控制方案和原理的设计和论证,在该方案中,采用了一种阻抗控制结构结合超声波传感器获取的外部信息实现移动机器人躲避行走路径上的障碍物;采用了Microsoft sidewinder 力反馈能手操纵杆对远程机器人实现本地人工操纵。本文给出了该设计案例的设计任务、运动方程、总体控制方案、控制结构原理、关键部件分析等。通过具体分析,该遥控系统控制方案是切实有效的,可以在工业远程机器人的具体应用中设计采用。     

改进MMAS算法的移动机器人的路径规划

移动机器人路径规划是机器人研究领域的重要内容之一,具有非线性、约束性和复杂性等特点。MMAS算法是近年来发展起来的一种智能优化算法,该算法在解决许多复杂问题方面已经展现出其良好的性能和巨大的发展潜力,但在应用上还存在一定的缺点。通过对MMAS算法的改进对移动机器人在复杂地图中全局路径规划问题进行了研究。     

基于方向选择的移动机器人路径规划方法

针对快速行进树算法(FMT*)在逐层递归扩展中产生的冗余探索问题,提出一种基于方向选择的快速行进树算法(DS-FMT*).该算法首先对拟扩展样本的四周产生均匀分布的方向选择线,判断周围的障碍物情况并选择有利于扩展的方向作为候选探索方向.随后将拟扩展到下一样本的实际探索方向与候选探索方向做比对,若实际探索方向与候选探索方...     

Decentralized control of mobile robots in formation

A control scheme for mobile robot formation in the leader following mode is proposed. It enables to track the target and is based on using a sliding mode along the desired trajectory in the state space. Results of modeling using MATLAB/SIMULINK environment are presented. They confirm efficiency of the proposed algorithm.