链式系统轨迹跟踪控制:一种新方案

研究了链式系统的轨迹跟踪控制问题,提出了一种新的跟踪方案,设计出能实现全避轨迹跟踪的静态控制器。它克服了用动态反馈线性化方法设计出控制器的两个缺点;控制器维数高和闭环系统有奇异点,将其用于一类轮式机器人的控制中,仿真结果表明了所提出方法的有效性。     

一类欠驱动机械系统的模糊与变结构控制

针对体操机器人这类欠驱动机械系统,提出一种模糊与变结构控制策略.首先用逻辑模糊控制实现快速平滑的摇起;然后用模糊变结构控制确保从摇起区快速进入平衡区;最后用基于Takagi-Sugeno模糊模型的模糊控制达到较大范围内的平衡控制.     

基于Lyapunov稳定性理论的移动机器人轨迹跟踪控制

针对非完整轮式移动机器人的高度强耦合、欠驱动非线性动力学模型,设计了运动学控制器以及动力学力矩控制器,使得移动机器人轨迹能够跟踪理想轨迹。这种方法的实质是首先设计虚拟速度控制器,输出速度的期望值,然后设计基于模型的力矩控制器。最后通过simulink软件对所设计的系统进行仿真,结果表明对于非完整机器人的轨迹跟踪这种控制方法效果较好。     

Global Adaptive Neural Network Control of Underactuated Autonomous Underwater Vehicles with Parametric Modeling Uncertainty

This paper focuses on global adaptive neural network control for a class of underactuated autonomous underwater vehicles in the presence of possibly large modeling parametric uncertainty. As the control inputs cannot directly act in the sway and heave directions, two virtual velocities defined here, plus three actual control actions provided by the thrusters and rudders, are used to achieve the convergence of the system errors to around zero. Motivated by real‐time characteristics in the trajectory tracking, the proposed controller presents a significant advantage because it contains only one adaptive parameter to be updated online rather than the neural network weights. In addition, we also consider the practical situation that the velocities of the vehicle may experience sharp speed jumps when the position tracking errors initially change suddenly, which always results in thruster saturation. The biologically inspired model is introduced to smooth the virtual velocity commands such that the vehicle satisfies the control input and velocity constraints. Finally, comparison simulations are given to show the effectiveness of the proposed scheme.     

一类欠驱动机械系统的动态及其稳定控制

Abstract The control of underactuated mechanical systems is very complex for the loss of its control inputs. The model of underactuated mechanical systems in a potential field is built with Lagrangian method and its structural properties are analyzed in detail. A stable control approach is proposed for the class of underactuated mechanical systems. This approach is applied to an unde ractuated double-pendulum-type overhead crane and the simulation results illustrate the correctness of dynamics analysis and validity of the proposed control algorithm.     

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 .     

一类欠驱动机械系统的非线性控制

针对一类欠驱动机械系统．分析了其数学模型,提出了一种基于部分反馈线性化的非线性控制方案．该方案利用精确线性化的方法将欠驱动系统直接激励部分线性化,将被动部分作为系统的内部动态考虑;并选择直接激励的自由度作为系统输出．进行系统的轨迹跟踪控制;通过分析系统的内部动态,证明了零动态的稳定性能保证控制系统的稳定性．最后通过对吊车的负载防摆控制的研究．验证了该方案的可行性．     

Adaptive Control for Simultaneous Stabilization and Tracking of Unicycle Mobile Robots

A novel time‐varying adaptive controller at the torque level is proposed to simultaneously solve the stabilization and the tracking problem of unicycle mobile robots with unknown dynamic parameters. The idea underlying the controller is intuitively simple: rather than switching between two different types of controllers according to the a priori knowledge of the reference velocities being persistently exciting or not, a new time‐varying signal is introduced to make the single controller capable of adaptively, smoothly, and gradually converting between stabilizer and tracker depending on the instantaneous and past information of the reference velocities. Our control development is based on Lyapunov's direct method and the backstepping technique. Adaptive control techniques are used to deal with parametric uncertainties. The outstanding feature of our controller is computationally simple due to its full use of the existing results on stabilization and tracking control for unicycle robots. With our approach, robots can globally follow a large class of paths including a straight line, a circle, a path approaching a set‐point, or just a set‐point using a single controller. Simulation results for a unicycle‐type mobile robot are provided to illustrate the effectiveness of the proposed controller.     

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.     

基于自适应滑模的欠驱动无人艇轨迹跟踪控制算法

针对欠驱动水面无人艇在航行过程中存在的海洋环境干扰、数学模型参数不确定、执行器故障等问题,提出了一种基于扰动观测器与神经网络技术的自适应滑模轨迹跟踪策略。在无人艇三自由度模型的基础上,结合视线制导率,提出了一种新的轨迹跟踪制导策略。采用自适应滑模控制技术设计了欠驱动无人艇轨迹跟踪控制器,有效地抑制了执行器衰减故障对无人艇控制系统的影响;同时运用了非线性扰动观测器和自适应径向基函数神经网络分别对无人艇受到的外界干扰和模型参数不确定性进行补偿和拟合,提高了控制系统的抗干扰能力。基于Lyapunov定理证明了所设计的控制系统的稳定性,并在MATLAB中进行了仿真测试。仿真结果表明,所提出的轨迹跟踪控制算法可以在较为复杂的环境下实现对欠驱动无人艇的精准控制;相较于对比算法,位置的平均跟踪误差减小了80%以上,具备较高的稳定性和鲁棒性。     

无人驾驶车路径跟踪控制研究

研究被控对象无人驾驶车,基于预瞄控制思想,设计一种无人驾驶车路径跟踪控制器,将控制器分为预瞄控制和补偿控制两部分,预瞄控制模拟驾驶员在驾驶车辆过程中对前方的道路环境信息进行预瞄,根据道路曲率程度决定方向盘转向,补偿控制是对车辆遇到干扰偏离原车道的纠正。仿真实验结果表明,该控制器能够保证无人驾驶车准确跟踪各种参考路径,且具有较好的鲁棒性。     

基于迭代学习的农业车辆路径跟踪控制

由于农作物的播种、收获、除草和农药化肥喷洒具有周期性的特点,农业车辆在执行农田作业时具有较强的重复性. 基于迭代学习控制（Iterative learning control,ILC）方法研究农业车辆的路径跟踪问题,建立了农业车辆的两轮移动机器人运动学模型,设计了车辆路径跟踪的迭代学习控制算法,并基于压缩 映射方法理论上证明了算法的收敛性. 研究表明,迭代学习控制可有效利用农业车辆运行的重复信息,实现车辆期望路径有限区间内的高精度完全跟踪控制. 仿真示例验证了本文方法的有效性.     

网络控制系统跟踪问题的研究

基于实际应用和学术发展的需要,研究了网络控制系统的跟踪问题。将时变时延转化为固定时延,并进行一个等价变换;对于等价变换后的网络控制系统,设计最优跟踪控制律。证明了该变换不改变系统的能控性和能观性;推导了最优控制律存在的条件。在最优控制律存在的条件下,证明了此最优控制律能使系统最后的跟踪误差为零。仿真试验表明,该方法设计的控制律可以使系统实现跟踪控制。     

智能车辆的滑模轨迹跟踪控制

智能车辆是集各种机械装置、传感器、计算机于一体的复杂非线性系统,其轨迹跟踪控制器是研究的关键技术之一。针对高速自主导航智能车辆轨迹跟踪控制器鲁棒性、精确性和实时性的高要求,在智能车辆结构组成与运动模型基础上,设计了一种滑模变结构控制器。通过控制智能车辆的线速度和角速度实现智能车辆对任意路径的跟踪,并用Matlab进行了仿真实验。结果验证了该方法的有效性和可靠性。     

Finite‐Time Sliding Mode Trajectory Tracking Control of Uncertain Mechanical Systems

The problem of finite‐time tracking control is studied for uncertain nonlinear mechanical systems. To achieve finite‐time convergence of tracking errors, a simple linear sliding surface based on polynomial reference trajectory is proposed to enable the trajectory tracking errors to converge to zero in a finite time, which is assigned arbitrarily in advance. The sliding mode control technique is employed in the development of the finite‐time controller to guarantee the excellent robustness of the closed‐loop system. The proposed sliding mode scheme eliminates the reaching phase problem, so that the closed‐loop system always holds the invariance property to parametric uncertainties and external disturbances. Lyapunov stability analysis is performed to show the global finite‐time convergence of the tracking errors. A numerical example of a rigid spacecraft attitude tracking problem demonstrates the effectiveness of the proposed controller.     

Three‐Dimensional Constrained Tracking Control Via Exact Differentiation Estimator of a Quadrotor Helicopter

In this paper, a constructive method is presented to design a three dimensional trajectory tracking controller that forces a quadrotor helicopter to track a bounded and sufficiently smooth reference trajectory asymptotically in the presence of constant force disturbances. The quadrotor helicopter under consideration has fewer independent thrusters than degrees of freedom to be controlled. Motivated by the vehicle's steering practices, the roll and pitch angles are regarded as virtual controls along with four control forces to fulfill the task of position and yaw angle reference tracking. To prevent position constraint violation, the barrier Lyapunov function (BLF) is employed in the vectorial backstepping procedure to guarantee that the position and attitude constraints are not violated. The backstepping procedure employs an exact and robust sliding mode differentiator of order two to facilitate the implementation of the attitude command signal without calculating the virtual control signal derivative analytically.     

Time‐varying linear controllers for exponential tracking of non‐holonomic systems in chained form

In this paper, the authors address the tracking problem for non‐holonomic systems in chained form with target signals that may exponentially decay to zero. By introducing a time‐varying co‐ordinate transformation and using the cascade‐design approach, smooth time‐varying controllers are constructed, which render the tracking‐error dynamics globally ??‐exponentially stable. The result shows that the popular condition of persistent excitation or not converging to zero for the reference signals is not necessary even for the globally ??‐exponential tracking of the chained‐form system. The effectiveness of the proposed controller is validated by simulation of two benchmark mechanical systems under non‐holonomic constraints. Copyright © 2006 John Wiley & Sons, Ltd.     

车载惯性平台随动系统的自抗扰控制

针对车载惯性随动平台的扰动特性,提出了随动伺服回路的自抗扰控制算法。该方法不需要精确的系统数学模型,具有强鲁棒性、快速性、高精度、方法简单等特点。仿真和实验结果表明,该方法调转时间短,抗干扰能力强,是一种应用在实际平台系统中的理想的控制器。     

Nonlinear Control of a Robot Manipulator with a Nonholonomic Jerk Constraint

We study the control of a prismatic‐prismatic‐revolute (PPR) robot manipulator subject to a nonholonomic jerk constraint, i.e., a third‐order nonintegrable design constraint. The mathematical model is obtained using the method of Lagrange multipliers. The control inputs are two forces and a torque applied to the prismatic joints and the revolute joint, respectively. The control objective is to control the robot end‐effector movement while keeping the transverse jerk component as zero. The main result of the paper is the construction of a feedback control algorithm that transfers the manipulator from any initial equilibrium configuration to the zero equilibrium configuration in finite time. The effectiveness of the algorithm is illustrated through a simulation example.