基于观测器的轮式移动机器人路径跟踪控制

研究基于状态观测器的轮式移动机器人的路径跟踪控制问题.首先简要回顾了基于状态反馈的移动机器人的路径跟踪控制问题;进而通过适当的状态变换将移动机器人模型转换为合适的形式,并在移动机器人的位置可以测量的情况下设计了一种可保证状态观测误差指数收敛的状态观测器;最后结合状态反馈路径跟踪控制器和所设计的观测器得到了一种基于观测器的路径跟踪控制器,该控制器可以保证移动机器人的运动轨迹指数收敛到期望路径上.仿真结果证实了所提出的基于观测器的路径跟踪控制器的有效性.     

基于Backstepping方法的移动机器人路径跟踪问题研究

针对轮式移动机器人的路径跟踪问题以及其非完整特性,引入一种新的虚拟反馈量,使用反演法设计了路径跟踪控制器.首先通过移动机器人的运动学模型得出其运动学位姿误差微分方程,然后基于Backstepping(逐步后推)方法设计控制器,通过构造的Lyapunov函数证明了所设计的控制器的稳定性;最后用Matlab进行仿真以及SM35机器人进行实验,结果表明,所设计的控制器能使移动机器人以任意小的误差跟踪任意给定的参考路径.     

基于自适应和神经动力学的轮式移动机器人路径跟踪控制(英文)

本文提出一种自适应和神经动力学相结合的轮式移动机器人路径跟踪控制方法.首先,设计运动学控制器用来获得机器人期望速度;其次,考虑机器人动力学模型参数的不确定性,利用模型参考自适应方法来设计动力学控制规律,使得机器人实际速度渐近逼近期望值;再次,为克服速度和力矩的跳变,加入神经动力学模型对控制器进行优化,并且通过Lypunov理论来证明整个控制系统的稳定性;最后仿真结果表明该控制方法的有效性.     

基于T-S模型的轮式移动机器人轨迹跟踪控制

针对带有执行机构饱和约束与外部干扰的轮式移动机器人,提出了一种基于T-S模糊模型的轨迹跟踪方法.利用机器人运动特性和参考轨迹建立轨迹跟踪的误差系统并将其作T-S模型描述.通过求解具有LMI约束的半定规划问题,对每个线性子系统单独设计满足控制约束与H∞性能约束的状态反馈控制器,并在PDC(动态平行分配补偿)设计框架下构建全局控制器,最后证明闭环系统的李雅普诺夫稳定性.仿真结果验证了该方法的有效性和可行性.     

农业轮式移动机器人反演自适应滑模轨迹跟踪控制

为提高农业轮式移动机器人路径跟踪控制的鲁棒性,提出一种基于农业轮式移动机器人反演自适应滑模控制策略。运用反演控制设计其运动学控制律,保证位置跟踪误差渐进收敛到零;根据动力学模型,设计自适应滑模动力学控制律,实现农业轮式移动机器人左右轮平稳的运行;运用李雅普诺夫定理保证闭环系统的最终一致稳定性。仿真实验验证了该方法的有效性和优越性,能够实现正弦型曲线路径跟踪。     

基于RBF神经网络的轮式移动机器人轨迹跟踪控制

针对一类非完整移动机器人的轨迹跟踪控制系统,提出一种基于RBF神经网络的滑模控制与转矩控制相结合的智能控制方法。该方法同时考虑机器人运动学和动力学模型,通过RBF神经网络进行移动机器人运动过程学习,与速度误差结合构成力矩控制器,可保证闭环误差系统一致最终渐进稳定。采用基于李亚普诺夫(Lyapunov)稳定性理论的判稳方法,证明整个闭环控制系统的稳定性。仿真结果表明,该控制方案具有较强的鲁棒性。     

轮式移动机器人航向跟踪预估控制算法

本文提出了一种轮式移动机器人航向跟踪预估控制算法,航向预估量根据机器人前 轮偏角和纵向速度实时得出,预估量与机器人实际航向之和作为控制反馈航向.仿真和实验 时用PID控制器和航向预估算法结合进行航向跟踪,结果表明该算法与常规PID算法相比,对 机器人纵向速度适应范围较宽,能有效地改善控制器的动态特性,表现出了较好的自适应能 力.     

基于Haar小波分解的轮式移动机器人轨迹跟踪控制

利用Haar小波在满足机器人动力学约束的前提下 ,对期望轨迹进行曲线分解 ,得到所需的一系列参考点 ,并由这些参考点构造出虚拟小车的运动轨迹 .基于控制Lyapunov函数设计了速度跟踪控制律 ,驱动机器人跟随虚拟小车实现对期望轨迹的跟踪 .该方法的突出特点是可实现对任意复杂轨迹的跟踪控制 ,且不存在速度跳跃点 .仿真实验结果表明它的有效性 .     

轮式移动机器人轨迹跟踪控制研究

针对轮式移动机器人参数摄动和内外部扰动等问题,提出一种新型的基于自适应扩张状态观测器的滑模控制算法。采用自适应虚拟速度控制器估计系统未知参数,滑模控制器抑制参数摄动和内外部扰动,非线性扩张状态观测器观测系统扰动并减小控制输入的抖振,实现了轨迹跟踪误差的快速收敛。利用Lyapunov稳定性理论证明了控制算法的稳定收敛性。将所提算法与传统自适应反演滑模算法进行对比,对比结果表明了所提算法的有效性和鲁棒性。     

Nonlinear model predictive control for path following problems

This paper presents a general nonlinear model predictive control scheme for path following problems. Path following problem of nonlinear systems is transformed into a parameter‐dependent regulation problem. Sufficient conditions for recursive feasibility and asymptotic convergence of the given scheme are presented. Furthermore, a polytopic linear differential inclusion‐based method of choosing a suitable terminal penalty and the corresponding terminal constraint are proposed. To illustrate the implementation of the nonlinear model predictive control scheme, the path following problem of a car‐like mobile robot is discussed, and the control performance is confirmed by simulation results. Copyright © 2014 John Wiley & Sons, Ltd.     

Adaptive sliding mode trajectory tracking control for wheeled mobile robots

This paper discusses the problem of adaptive sliding mode trajectory tracking control for wheeled mobile robots in the presence of external disturbances and inertia uncertainties. A new fast nonsingular terminal sliding mode surface without any constraint is proposed, which not only avoids singularity, but also retains the advantages of sliding mode control. In order to implement the trajectory tracking mission, the error dynamic system is divided into a second-order subsystem and a third-order one. First, an adaptive fast nonsingular terminal sliding mode control law of the angular velocity is constructed for stabilising the second-order subsystem in finite time. Then, another adaptive fast nonsingular terminal sliding mode control law of the linear velocity is designed to guarantee the stability of the third-order subsystem. Finally, a simulation example is provided to demonstrate the validity of the proposed control scheme.     

Control of wheeled mobile robots not satisfying ideal velocity constraints: A singular perturbation approach

We propose in this paper a singular perturbation formulation for mechanical systems not exactly satisfying velocity constraints. We particularize to ‘wheeled mobile robots’ which do not satisfy ideal pure rolling and nonslipping constraints. We study the robustness of static-state linearizing feedback laws which have been obtained to solve a point tracking problem in the ideal case when constraints were satisfied.     

Quasi-min-max MPC for visual servoing stabilization of omnidirectional wheeled mobile robots

This paper proposes a new visual servoing quasi-min-max MPC algorithm for stabilization control of an omnidirectional wheeled mobile robot subject to physical and visual constraints. The visual servoing dynamics of the robot are modeled as the state-dependent linear error system with nonlinear control inputs of rotation and deflection velocities of wheels. The state-dependent linear error system is covered as linear parameters-varying models which is used to design the visual servoing quasi-min-max MPC controller. The actual control inputs of the robot are then computed by the solution of an inverse algebraic equation of the MPC actions. The recursive feasibility and stability of the new visual servoing MPC are ensured by some LMIs conditions. The performance and practicability of the visual servoing MPC are verified by some simulation and experiment results.     

A novel saturated PID-type observer-based controller for wheeled mobile robots with a guaranteed performance considering path curvature

This article proposes a novel saturated PID-type formation controller for a class of nonholonomic wheeled mobile robots (WMRs) of type (m, s) with mobility m and steerability s. Since the path curvature causes a severe deviation of the followers from the leaders' trajectory in the corners, a new definition of output equations is suggested to construct the coordinates of a virtual reference point in the front of each follower based on the concept of the extended look-ahead control that utilizes a corrective angle to compensate the trajectory curvature efficiently. A nonlinear transformation and the robot's kinematic and dynamic equations are heuristically combined to develop a novel second-order Euler–Lagrange formulation of unconstrained errors from constrained errors. Then, a novel saturated PID-type controller is proposed for WMRs to build a desirable formation with a prescribed performance. An innovative nonlinear observer is presented to estimate followers' velocities. An efficient mixture of a radial basis function neural network (RBFNN) and an adaptive mechanism is proposed to compensate for model uncertainties, external disturbances, and network approximation errors. Lyapunov's direct method verifies semi-global uniform ultimate boundedness stability by estimating a gain-dependent region of attraction. Numerical simulations finally show the efficiency of the proposed controller.     

Nonsingular path following control of a unicycle in the presence of parametric modelling uncertainties

A new type of control law is derived to steer the dynamic model of a wheeled robot of unicycle type along a desired path. The methodology adopted for path following control deals explicitly with vehicle dynamics and plant parameter uncertainty. Furthermore, it overcomes stringent initial condition constraints that are present in a number of path following control strategies described in the literature. This is done by controlling explicitly the rate of progression of a ‘virtual target’ to be tracked along the path, thus bypassing the problems that arise when the position of the virtual target is simply defined by the projection of the actual vehicle on that path. In the paper, a nonlinear adaptive control law is derived that yields convergence of the (closed‐loop system) path following error trajectories to zero. Controller design relies on Lyapunov theory and backstepping techniques. Simulation results illustrate the performance of the control system proposed. Copyright © 2006 John Wiley & Sons, Ltd.     

非完整轮式机器人的鲁棒同步编队跟踪及镇定控制

本文研究了受到建模不确定性影响和输入限制的非完整轮式机器人的同步编队跟踪和编队镇定问题.首先,基于领航–跟随策略,确定了编队构型的数学表达形式.其次,通过定义含有辅助控制量的跟踪误差,设计了一种具有统一结构的分布式运动学控制器,可使跟随者实现对复杂期望轨迹的跟踪,包括时变轨迹和固定点等.然后,针对建模不确定性影响和输入限制,基于反步法、模糊控制方法和Lyapunov控制理论,设计了一种饱和动力学控制器,使得系统的闭环跟踪误差全局收敛至零点附近有界领域内.最后,通过对比仿真实验,验证了本文控制方法的有效性.     

Robust discontinuous exponential regulation of dynamic nonholonomic wheeled mobile robots with parameter uncertainties

For regulating a dynamic nonholonomic WMR (wheeled mobile robot) with parameter uncertainties, we derive a simple robust discontinuous control law, yielding a global exponential convergence of position and orientation to the desired set point despite parameter uncertainties. The controller design relies on separating the error dynamics into two subsystems, followed by robust feedback control laws to stabilize the subsystems. The effectiveness of the proposed control laws is verified by simulation. Copyright © 2007 John Wiley & Sons, Ltd.     

轮式移动机器人的位置量测输出反馈轨迹跟踪控制

针对机器人的姿态角难以精确测量的困难,本文研究基于位置测量的轮式移动机器人的轨迹跟踪问题.首先提出一种利用机器人的位置信息估计其姿态角的降维状态观测器,当机器人的线速度严格大于零时,可保证姿态角观测误差的指数收敛.然后给出一种新的状态反馈轨迹跟踪控制律,当参考轨迹满足一定的激励条件时,可以保证机器人的线速度严格大于零且跟踪误差全局渐近收敛.进一步结合姿态角观测器和状态反馈控制律,得到一种输出反馈轨迹跟踪控制算法.理论分析表明,当参考轨迹满足一定的激励条件时,所提出的输出反馈控制算法可以保证跟踪误差的全局渐近收敛.最后对所提出的姿态角观测器、状态反馈和输出反馈轨迹跟踪控制算法进行了仿真验证,证实了算法的有效性,并且当存在位置测量误差时,所提出的输出反馈轨迹跟踪控制算法仍可以保证机器人对参考轨迹的实际跟踪.