Nonlinear tracking control of trailer systems using the Lyapunov direct method

This article concerns the nonlinear tracking control of trailer systems that consist of a steering tractor and a passive trailer, linked together with rigid joint and having nonholonomic velocity constraints. We propose a globally asymptotically stable (GAS) tracking control law using the Lyapunov direct method. The GAS tracking control law is completed by considering the posture term of the trailer systems. We selected two types of trailer systems for examples: the two‐wheeled trailer system and the car‐like trailer system. The simulation results represent the effectiveness of our proposed method. In addition, there is a plan to test the path following ability of the trailer system. ©1999 John Wiley & Sons, Inc.     

Backward movement control with two-trailer truck system using genetic programming

In this paper, we propose a control system using genetic programming (GP) for backward movement control of a two-trailer truck, known as a nonholonomic system. We have already achieved the control of a single trailer using GP. In this study, we aim to design a control system for complex problem of two trailers. In order to verify the effectiveness of the proposed method, it is compared to neuro controller (NC) system evolved by genetic algorithm (GA). This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Dyamic modelig ad trackig cotrol of a car with $$ trailers

Tractor–trailer systems as multibody modular robotic systems have been widely used to increase load transportation capacity. Control of these systems started from motion aid facilities in human-driven vehicles to fully autonomous mobile robots in recent years. The mobility of these systems is restricted due to the presence of nonholonomic constraints of wheels and also to the system severe underactuated nature. Several control problems are under research for autonomous navigation of such systems. Trajectory tracking is one of the main problems in the context of autonomous nonholonomic systems. In this paper, dynamic modeling and control of a car with \(n\) trailers have been developed. First, a dynamic model of the system is obtained. Next, an output feedback kinematic controller and a feedback linearization kinetic controller have been used for tracking control of the system. Finally, experimental results are presented to show the merits of the proposed method.     

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).     

移动机器人的全局轨迹跟踪控制

考察了移动机器人的轨迹跟踪问题,针对以前沿袭线性化的思路设计的控制律带来 的局部稳定特性,基于后退(backstepplng)方法的思想设计了具有全局渐近稳定的跟踪控制 器.该方法将系统分解为低阶子系统来处理,利用中间虚拟控制量和部分Lyapunov函数简 化了控制器的设计并具有直观的稳定性分析.仿真结果验证了所设计控制器的有效性.     

Adaptive output feedback tracking control of a nonholonomic mobile robot

An adaptive output feedback tracking controller for nonholonomic mobile robots is proposed to guarantee that the tracking errors are confined to an arbitrarily small ball. The major difficulties are caused by simultaneous existence of nonholonomic constraints, unknown system parameters and a quadratic term of unmeasurable states in the mobile robot dynamic system as well as their couplings. To overcome these difficulties, we propose a new adaptive control scheme including designing a new adaptive state feedback controller and two high-gain observers to estimate the unknown linear and angular velocities respectively. It is shown that the closed loop adaptive system is stable and the tracking errors are guaranteed to be within the pre-specified bounds which can be arbitrarily small. Simulation results also verify the effectiveness of the proposed scheme.     

基于输出反馈的非完整链式系统跟踪控制研究

针对非完整链式系统设计了基于输出反馈的全局跟踪控制律. 首先, 利用时变坐标变换和非自治系统的级联控制方法构造了状态观测器;然后对于时变坐标变换以后的误差系统继续利用非自治系统的级联控制方法设计了输出跟踪控制律. 区别于已有文献对于非完整链式系统跟踪控制问题的研究, 设计得到的输出跟踪控制律放松了参考轨迹所必需满足的不趋于零条件或持续激励条件. 结论表明在非完整链式系统跟踪控制问题 的研究中, 参考轨迹所必须满足的不趋于零的条件或者持续激励条件是不必要的. 最后的仿真结果验证了所给控制方法的有效性.     

带有未知参数和有界干扰的移动机器人轨迹跟踪控

针对模型参数未知和存在有界干扰的非完整移动机器人的轨迹跟踪控制问题,本文提出了一种鲁棒自适应轨迹跟踪控制器方法.非完整移动机器人的控制难点在于它的运动学系统是欠驱动的.针对这一难点,本文利用横截函数的思想,引入新的辅助控制器,使得非完整移动机器人系统不再是一个欠驱动系统,缩减了控制器设计的难度,进而利用非线性自适应算法和参数映射方法构造李雅谱诺夫函数.通过李雅普诺夫方法设计控制器和参数自适应器,从而使得非完整移动机器人的跟随误差任意小,即可以任意小的误差来跟随任意给定的参考轨迹.仿真结果证明了方法的有效性.     

基于模糊控制的移动机器人视觉反馈跟踪

探讨视觉空间下非完整移动机器人的跟踪问题。在不校准摄像机视觉参数的前提下,提出一种利用视觉反馈信息设计非完整移动机器人轨迹跟踪的模糊控制方法。其模糊控制使用Mamdani推理机,包含if-then规则和重心法,对线速度和角速度进行控制。仿真结果证明了该方法的有效性。     

An ESO-based integrated trajectory tracking control for tractor–trailer vehicles with various constraints and physical limitations

This paper develops an effective integrated control strategy for the trajectory tracking control of a tractor–trailer vehicle which suffers from inaccessible system states and uncertain disturbance for practical implementation. In addition, diverse problems, such as nonholonomic constraints, underactuated dynamics, physical limitations, etc, can be resolved favourably all together. Aiming to the vehicle trajectory tracking, a constrained model predictive control (MPC) is introduced as a trajectory tracking module, by which the underactuated dynamics, various constraints and physical limitations, can be tackled at the same time. For the desired velocity tracking, a robust global terminal sliding mode control (GTSMC) is employed to guarantee the finite-time convergence of the velocity tracking process, which will improve the transient performance to a great extent. Particularly, in the absence of velocity information, an extended state observer (ESO) is developed to estimate the vehicle velocity in addition to simultaneously obtaining the uncertain disturbance information, which offers prerequisite for the previous control approaches. The simulation results confirm that the presented control strategy can synthesise varied control techniques effectively and deal with diverse problems for the trajectory tracking of tractor–trailer vehicles successfully.     

控制受限的移动机器人鲁棒跟踪控制器设计

研究了非完整移动机器人动力学模型中带有参数不确定和控制受限的鲁棒轨迹跟踪控 制器的设计问题.在建立移动机器人的全动态误差模型的基础上,应用滚动时域控制(RHC)和线 性矩阵不等式(LMIs)方法,设计了鲁棒跟踪控制器,在满足非完整和控制约束的条件下,实现了 机器人位置,导向角以及速度的同时渐近跟踪.系统稳定性的充分条件以LMI的形式给出.仿真 结果验证了提出方法的可行性和有效性.     

基于高增益观测器的AUV水平面轨迹跟踪控制

通过研究欠驱动自治水下机器人（AUV）在水平面的运动规律,针对欠驱动AUV水平面轨迹跟踪控制中的非完整约束、模型中的耦合性和非线性、海流干扰、跟踪精度问题进行了深入的研究,运用高增益观测器结合反步控制方法对欠驱动AUV轨迹跟踪进行有效控制。定义了AUV的地面坐标系和船体坐标系,并完成了地面坐标系向船体坐标系的转换,建立了欠驱动AUV的水平面运动学模型和动力学模型。为欠驱动AUV所提出的高增益观测器结合反步控制方案,在保证跟踪系统稳定性的前提下,可以有效地提高跟踪精度,能够消除外界干扰对控制效果的影响,并使得控制输入满足实际工程的应用约束条件。控制方法的稳定性均采用Lyapunov稳定性理论加以证明,并通过数值仿真验证了所设计控制器的有效性。     

Cooperative adaptive consensus tracking for multiple nonholonomic mobile robots

This paper addresses the cooperative adaptive consensus tracking for a group of multiple nonholonomic mobile robots, where the nonholonomic robot model is assumed to be a canonical vehicle having two actuated wheels and one passive wheel. By integrating a kinematic controller and a torque controller for the nonholonomic robotic system, a cooperative adaptive consensus tracking strategy is developed for the uncertain dynamic models using Lyapunov-like analysis in combination with backstepping approach and sliding mode technique. A key feature of the developed adaptive consensus tracking algorithm is the introduction of a directed network topology into the control constraints based on algebraic graph theory to characterise the communication interaction among robots, which plays an important role in realising the cooperative consensus tracking with respect to a specific common reference trajectory. Furthermore, a novel framework is proposed for developing a unified methodology for the convergence analysis of the closed-loop control systems, which can fully ensure the desired adaptive consensus tracking for multiple nonholonomic mobile robots. Subsequently, illustrative examples and numerical simulations are provided to demonstrate and visualise the theoretical results.     

非完整移动机器人道路跟踪控制器设计及应用

讨论一类非完整约束条件下的移动机器人道路跟踪控制问题，综合后推方法与模糊滑模控制方法设计非完整移动机器人的状态反馈控制系统，并根据Lyapunov稳定性定理后推设计时变光滑反馈控制律，当存在较大侧向误差时，模糊滑模控制器确保移动机器人沿稳定的工作区域减小误差；当误差比较小时，时变光滑状态反馈控制实现对移动机器人的平稳镇定，采用移动机器人Amigobot作为实验平台，验证了控制器设计的有效性。     

轮式移动机械臂的建模与仿真研究

移动机械臂系统一般由移动平台和机器臂组成,它既具有机器臂的操作灵活性,又具有移动机器人的可移动性,因此其应用范围要比单个系统宽得多。这篇文章主要研究了由非完整移动平台和完整机械臂组成的轮式移动机械臂系统的建模、跟踪控制及仿真问题。首先。利用拉格朗日动力学方程和非完整动力学罗兹方程建立了移动机械臂系统的精确数学模型;然后。利用非线性反馈将系统解耦。采用类PD控制器进行控制。在考虑了非完整约束及移动平台和机械臂的动态交互影响情况下,该控制算法保证系统同时跟踪给定的终端执行器和平台轨迹;最后,使用Maflah6．5对系统进行了仿真研究,仿真结果表明了其数学模型及控制方法的正确有效性。     

基于自适应Backstepping的欠驱动AUV三维航迹跟踪控制

为了实现欠驱动自治水下机器人（AUV）三维航迹跟踪控制,基于非完整系统理论分析了AUV缺少横向推进器时的欠驱动控制系统特性,并验证了欠驱动AUV存在加速度约束不可积性.基于李亚普诺夫稳定性理论,利用自适应Backstepping设计连续时变的航迹点跟踪控制器,以抑制外界海流的干扰.仿真实验表明,所设计的控制器能实现欠驱动AUV对一序列三维航迹点的渐近镇定,并且航迹跟踪的精确性和鲁棒性明显优于PID控制.     

Dynamic Modeling and Tracking Control of a Nonholonomic Wheeled Mobile Manipulator with Dual Arms

This paper presents methodologies for dynamic modeling and trajectory tracking of a nonholonomic wheeled mobile manipulator (WMM) with dual arms. The complete dynamic model of such a manipulator is easily established using the Lagrange’s equation and MATHEMATICA. The structural properties of the overall system along with its subsystems are also well investigated and then exploited in further controller synthesis. The derived model is shown valid by reducing it to agree well with the mobile platform model. In order to solve the path tracking control problem of the wheeled mobile manipulator, a novel kinematic control scheme is proposed to deal with the nonholonomic constraints. With the backstepping technique and the filtered-error method, the nonlinear tracking control laws for the mobile manipulator system are constructed based on the Lyapunov stability theory. The proposed control scheme not only achieves simultaneous trajectory and velocity tracking, but also compensates for the dynamic interactions caused by the motions of the mobile platform and the two onboard manipulators. Simulation results are performed to illustrate the efficacy of the proposed control strategy.     

Motion/force tracking control of nonholonomic mechanical systems via combining cascaded design and backstepping

This paper considers motion/force tracking control of a class of Lagrange mechanical systems with classical nonholonomic constraints. A tracking control method is proposed by combining cascaded methods and backstepping techniques. The main results of this paper include three parts: (1) error dynamics between the kinematic system and the desired paths are transformed into a cascaded system consisting of two subsystems and an interconnection function; (2) under the framework of cascaded methods, virtual controllers for the subsystems are designed to stabilize the error dynamics; (3) the tracking controller is designed for the overall mechanical systems using backstepping techniques.     

Global uniform asymptotical stability of a class of nonlinear cascaded systems with application to a nonholonomic wheeled mobile robot

In this article, we consider the stability analysis problem for a class of nonlinear cascaded systems by using homogeneous properties. Assume that the driving subsystem and the driven subsystem are both homogeneous and locally uniformly asymptotically stable. If the cascaded term satisfies a given inequality, then the cascaded system is globally uniformly asymptotically stable. Furthermore, in the case that both degrees of homogeneity are negative, the cascaded system is globally uniformly finite-time stable. Compared with the existing methods, the conditions given in this article are much easier to verify. These stability results are applied to the global tracking control problem of a nonholonomic wheeled mobile robot. Simulation results are provided to show the effectiveness of the methods.     

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.