移动机械手的跟踪控制

讨论一类不确定非完整移动机械手的跟踪控制问题。在系统惯性参数不精确知道的情况下,提出一种鲁棒控制器。为提高跟踪性能,进一步设计出使跟踪误差指数收敛的控制器。计算机仿真验证了所提出控制律的有效性。     

移动机械手的鲁棒控制

讨论了受摩擦力、外界扰动及参数不确定的移动机械手控制问题. 基于Barbalat引理、系统的结构性质和定义的跟踪误差, 提出了鲁棒控制器. 该控制器能使系统的状态在参数不确定情况下全部渐进趋于给定的期望轨迹. 仿真结果验证了本文所提出控制方法的有效性.     

移动机械手运动/力鲁棒自适应轨迹跟踪

针对移动机械手控制器设计中用隐函数定理进行模型降阶时存在的一些问题,把完整和非完整约束的统一形式引入到系统的动力学模型降阶中．基于该降阶模型设计了不确定移动机械手稳定的运动／力鲁棒自适应线性参数模糊控制器．理论分析和仿真结果表明,设计的控制器简单有效．     

多机械手系统协调控制技术

本文重点介绍存在运动学约束和动力学约束条件下多机械手闭合链系统协调操作的主要技术问题。具体针对两机械手系统的协调控制问题,讨论了动力学建模方法,运动规划和控制问题。较为详细地归纳出两种基本控制方法,并对负载共享和应用软件及人工智能的应用等问题进行了介绍。     

移动机械手控制研究进展

我国在移动机械手方面所作的工作相对较少，本文针对移动机械手，重点从运动规划、协调控制和多移动机械手三个方面综述了近年来的发展状况，介绍了涉及的各种问题及相应的处理方法，同时探讨了这一研究领域的发展方向和需要解决的问题。     

移动双臂机械手系统协调操作的视觉伺服技术

本文利用双目泛倾斜变焦摄像机(pan-tilt-zoom,PTZ)像机,实现移动双臂机械手系统的视觉伺服协调操作,重点研究室内复杂环境和光照变化情况下目标物体的检测、识别和定位问题.首先,提出了色调、饱和度、亮度颜色模型(hue-saturation-value,HSV)空间下图像分割的改进算法,通过阈值更新和外接矩形改善分割结果,提高检测算法对环境光照变化的适应性;然后,基于Hu不变矩,利用物体形状特征,对检测得到的物体加以识别:在此基础上,利用摄像机投影矩阵,计算目标物体的空间坐标,实现其定位测量:最后,在实验室平台上,通过模拟双臂倒水操作,验证提出的图像处理和分析算法以及视觉伺服协调操作方案的有效性.实验结果表明移动双臂机械手系统能够成功完成倒水动作的协调操作.     

基于神经网络的内模控制在机械手控制中的研究

采用内模控制与神经网络相结合的方法来解决机械手的控制问题,使机械手沿着一定的期望轨迹运行。神经网络对机械手建模,使其作为内模控制中的模型,训练方法采用前馈网络的BP学习算法。单个神经元使用静态模型,输入神经元之间的延迟引入系统的动态。仿真结果表明,该方法具有有效性和实用性。     

非完整移动机械手鲁棒自适应模糊控制

考虑系统存在的参数、外界扰动和未建模动态等不确定性,研究非完整移动机械手的鲁棒自适应控制器设计方法.基于用旋量理论建立的非完整移动机械手的动力学模型,设计了移动平台子系统的运动控制器,然后应用非线性反步控制技术和模糊逻辑系统的通用逼近性,用参数化线性模糊逻辑系统逼近非完整移动机械手动力学模型中的不确定项,基于Lyapu...     

一种全方位移动机械手的体系结构设计与分析

首先介绍了我们设计和开发的一种全方位移动机械手系统的硬件体系结构,然后根据硬件平台、应用 环境和任务,设计了全方位移动机械手系统的基于行为的混合式软件体系结构,并通过两个实例进一步分析说明所 设计的体系结构的合理性和可行性,同时指出了下一步研究的方向.􀁱     

移动机械手鲁棒自适应模糊控制

基于旋量理论建立了非完整移动机械手系统的动力学模型,通过反步控制技术,应用非线性参数化模糊逻辑系统设计了移动机械手的鲁棒自适应模糊控制器.该控制器放松了移动机械手控制器设计中斜对称性的要求,对移动机械手系统中存在的参数或外界扰动等不确定性具有较强的鲁棒性和自适应能力.理论证明和仿真结果表明,所设计的控制器是有效的.     

Intelligent tracking control of a dual‐arm wheeled mobile manipulator with dynamic uncertainties

This paper presents an intelligent control approach that incorporates sliding mode control (SMC) and fuzzy neural network (FNN) into the implementation of back‐stepping control for a path tracking problem of a dual‐arm wheeled mobile manipulator subject to dynamic uncertainties and nonholonomic constraints. By using the back‐stepping technique, the system equations are reformulated into two levels: the kinematic level and the dynamic level. A sliding manifold is constructed by considering the disturbance free kinematic level equations only. With all the system uncertainties concentrated in the dynamic level, an FNN controller associated with a switching type of control law is employed to enforce sliding mode on the prescribed manifold. All parameter adjustment rules for the proposed controller are derived from the Lyapunov theory such that uniform ultimate boundedness for both the tracking error and the FNN weighting updates is ensured. A simulation study, which compares different control design approaches, is included to illustrate the promise of the proposed SMC–FNN method. Copyright © 2012 John Wiley & Sons, Ltd.     

Adaptive recurrent neural network control of uncertain constrained nonholonomic mobile manipulators

In this article, motion/force control problem of a class of constrained mobile manipulators with unknown dynamics is considered. The system is subject to both holonomic and nonholonomic constraints. An adaptive recurrent neural network controller is proposed to deal with the unmodelled system dynamics. The proposed control strategy guarantees that the system motion asymptotically converges to the desired manifold while the constraint force remains bounded. In addition, an adaptive method is proposed to identify the contact surface. Simulation studies are carried out to verify the validation of the proposed approach.     

移动机械手的T-S模糊控制系统

对移动机械手进行动力学分析,给出了统一的移动机械手整体动力学建模方法;针对移动机械手的非线性特点,提出T-S模糊控制算法,将复杂的非线性强耦合系统转化为若干线性问题的组合;利用线性矩阵不等式方法为该系统设计了状态反馈控制器,并给出了整体系统的稳定性证明。仿真实验证明该控制器具有良好的控制效果和稳定性。     

The VFO state-constrained stabilisation of the nonholonomic manipulator with limited control input

This article considers the state-constrained set-point feedback control problem for a configuration of the 3-link nonholonomic manipulator kinematics with amplitude-limited control inputs. The proposed solution results from applying the original, geometrical in nature, Vector-field-orientation (VFO) control strategy, which makes use of the intrinsic features of the manipulator kinematics. The concept does not involve any state transformation in contrast to the commonly applied solutions based on a chained-form conversion of the original model. The general formulation of the VFO approach makes it possible to derive a family of VFO controllers guaranteeing convergence of the configuration error to the assumed neighbourhood of zero. The VFO concept together with an additional switching strategy and input scaling procedure preserves both the state constraints and the control limitations. The effectiveness of the control scheme is illustrated by simulations.     

Robust tracking control of a unicycle-type wheeled mobile manipulator using a hybrid sliding mode fuzzy neural network

This article presents a robust tracking controller for an uncertain mobile manipulator system. A rigid robotic arm is mounted on a wheeled mobile platform whose motion is subject to nonholonomic constraints. The sliding mode control (SMC) method is associated with the fuzzy neural network (FNN) to constitute a robust control scheme to cope with three types of system uncertainties; namely, external disturbances, modelling errors, and strong couplings in between the mobile platform and the onboard arm subsystems. All parameter adjustment rules for the proposed controller are derived from the Lyapunov theory such that the tracking error dynamics and the FNN weighting updates are ensured to be stable with uniform ultimate boundedness (UUB).     

基于自适应动态规划的移动装弹机械臂轨迹控制

针对移动装弹机械臂系统非线性、强耦合、受多种不确定因素影响的问题,本文基于自适应动态规划方法,提出了仅包含评价网络结构的轨迹跟踪控制方法,有效减小了系统跟踪误差.首先,考虑到系统非线性特性、变量间强耦合作用及重力因素的影响,通过拉格朗日方程建立了移动装弹机械臂的动力学模型.其次,针对系统存在不确定性上界未知的问题,建立...     

Neuro-fuzzy and model-based motion control for mobile manipulator among dynamic obstacles

This paper focuses on autonomous motion control of a nonholonomic platform with a robotic arm, which is called mobile manipulator. It serves in transportation of loads in imperfectly known industrial environments with unknown dynamic obstacles. A union of both procedures is used to solve the general problems of collision-free motion. The problem of collision-free motion for mobile manipulators has been approached from two directions, Planning and Reactive Control. The dynamic path planning can be used to solve the problem of locomotion of mobile platform, and reactive approaches can be employed to solve the motion planning of the arm. The execution can generate the commands for the servo-systems of the robot so as to follow a given nominal trajectory while reacting in real-time to unexpected events. The execution can be designed as an Adaptive Fuzzy Neural Controller. In real world systems, sensor-based motion control becomes essential to deal with model uncertainties and unexpected obstacles.     

Robust tracking control for wheeled mobile robot based on extended state observer

This paper presents a new control scheme on trajectory tracking of wheeled mobile robot with nonholonomic constraints. Extended state observer is introduced to estimate unknown disturbances and velocity information. A robust tracking controller is designed to implement the accurate trajectory tracking and disturbance compensation. By theoretical, position and velocity tracking errors of wheeled mobile robot are proven uniformly ultimately asymptotically stable. Simulation results are given to illustrate the effectiveness of the developed technique.     

Switched visual servo control of nonholonomic mobile robots with field-of-view constraints based on homography

This paper presents a novel scheme for visual servoing of a nonholonomic mobile robot equipped with a monocular camera in consideration of field-of-view (FOV) constraints. In order to loosen the FOV constraints, the system states are expressed by the homography between the current frame and the key frame so that the target is not necessarily to be always visible in the control process. A switched visual controller is designed to deal with the nonholonomic constraints. Moreover, an iteration strategy is used to eliminate errors caused by the parameter uncertainty. The stablity and robustness of the proposed scheme are guaranteed by theoretical analysis. Compared to conventional schemes, the proposed approach has the following advantages: 1) a better path in Cartesian space can be achieved owing to the loosening of FOV constraints; 2) the iteration strategy ensures the robustness to parameter uncertainty; 3) when used in landmark-based navigation, it needs much sparser and simpler landmarks than those localization-based approaches need. Simulation results demonstrate the effectiveness of the proposed method.     

三连杆移动机械臂模型与运动规划

采用拉格朗日动力学方法和非完整动力学罗兹方程建立了三连杆移动机器臂运动学和动力学模型,并且利用该模型采用了人工势函数方法来驱动移动机械臂系统绕过障碍物到达目标位置.仿真的结果证明了该模型的正确性及其规划方法是有效的.