一类不确定非完整动力学系统的时变镇定

对于一类具有未知惯性参数的非完整动力学系统,提出了新的时变自适应镇定律,将其用于一类移动机器人的位姿镇定中．仿真结果验证了所提控制方法的有效性．     

Adaptive/robust time‐varying stabilization of second‐order non‐holonomic chained form with input uncertainties

Adaptive and robust time‐varying control schemes are constructed to stabilize second‐order non‐holonomic chained form in the presence of input uncertainties. The proposed control schemes guarantee that all the state variables converge to zero asymptotically in spite of input uncertainties, and are applied to the stabilization of a planar rigid body driven by active force and torque with unknown inertia and geometric parameters. The basic idea of the proposed stabilization schemes is to first convert the non‐holonomic system into a linear time‐varying form by time‐varying co‐ordinate transformation, and then design control laws to stabilize the converted linear time‐varying system. Copyright © 2002 John Wiley & Sons, Ltd.     

非完整链式系统的时变光滑指数镇定

针对非完整链式系统,导出了一种时变光滑反馈控制律,该控制律可以保证系统状态 全局指数收敛到原点,克服了以往控制律非光滑或虽光滑但却只能渐近镇定系统的缺陷.所得 控制律应用于移动机器人系统的镇定.     

一类不确定非完整动力学系统的鲁棒镇定*

研究了一类不确定非完整动力系统的鲁棒镇定问题,设计了时变镇定律,仿真表明了该镇定律有效性。     

不校准视觉参数的非完整运动学系统的鲁棒指数镇定

基于视觉反馈和非完整（1,2）型移动机器人的标准链式形式,探讨了具有不校准视觉参数的机器人的鲁棒镇定问题,得到了这种机器人在图像平面内新的非完整运动学系统的不确定链式模型.借助于状态缩放和切换技术,对非完整不确定链式模型提出了新的指数镇定的时变反馈控制器,并给出了指数镇定的严格证明.仿真结果验证了控制器设计的有效性.     

Variable structure exponential stabilization of chained systems based on the extended nonholonomic integrator

In this paper, a new variable structure control strategy for exponentially stabilizing chained systems is presented based on the extended nonholonomic integrator model, the discontinuous coordinate transformation and the “reaching law method” in variable structure control design. The proposed approach converts the stabilization problem of an n-dimensional chained system into the pole-assignment problem of an (n−3)-dimensional linear time-invariant system and consequently simplifies the stabilization controller design of nonholonomic chained systems.     

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.     

Tracking control of second‐order chained form systems by cascaded backstepping

A design methodology is presented for tracking control of second‐order chained form systems. The methodology separates the tracking‐error dynamics, which are in cascade form, into two parts: a linear subsystem and a linear time‐varying subsystem. The linear time‐varying subsystem, after the first subsystem has converged, can be treated as a chain of integrators for the purposes of a backstepping controller. The two controllers are designed separately and the proof of stability is given by using a result for cascade systems. The method consists of three steps. In the first step we apply a stabilizing linear state feedback to the linear subsystem. In the second step the second subsystem is exponentially stabilized by applying a backstepping procedure. In the final step it is shown that the closed‐loop tracking dynamics of the second‐order chained form system are globally exponentially stable under a persistence of excitation condition on the reference trajectory. The control design methodology is illustrated by application to a second‐order non‐holonomic system. This planar manipulator with two translational and one rotational joint (PPR) is a special case of a second‐order non‐holonomic system. The simulation results show the effectiveness of our approach. Copyright © 2002 John Wiley & Sons, Ltd.     

Stabilization of nonholonomic chained systems via nonregular feedback linearization

This paper addresses the problem of feedback stabilization of nonholonomic chained systems within the framework of nonregular feedback linearization. Firstly, the nonsmooth version of nonregular feedback linearization is formulated, and a criterion for nonregular feedback linearization is provided. Then, it is proved that the chained form is linearizable via nonregular feedback control, thus enable us to design feedback control laws using standard techniques for linear systems. The obtained discontinuous control laws guarantee convergence of the closed-loop system with exponential rates. Finally, simulation results are presented to show the effectiveness of the approach.     

一类不确定非完整动力学系统的时变镇定

对于一类具有未知惯性参数的非完整动力学系统,提出了新的时变自适应镇定律、 将其用于一类移动机器人的位姿镇定中.仿真结果验证了所提控制方法的有效性.     

离轴式拖车移动机器人的反馈镇定

由于离轴式拖车移动机器人的模型不能转化为非完整链式模型, 因而无法采用针对非完整链式模型的控制方法. 针对有多节离轴式拖车的移动机器人, 给出了一种基于时间–状态能控形的反馈镇定控制算法. 首先推导出系统的线性化时间–状态模型, 并证明了其能控性; 进而设计了一种线性切换反馈镇定控制律, 该控制律可以保证系统的状态在有限时间内收敛到原点的任意小邻域内. 仿真结果证实了所提控制算法的有效性.     

Stabilization of uncertain chained form systems within finite settling time

This note considers finite time stabilization of uncertain chained form systems. The objective is to design a nonsmooth state feedback law such that the controlled chained form system is both Lyapunov stable and finite-time convergent within any given settling time. We propose a novel switching control strategy with help of homogeneity, time-rescaling, and Lyapunov-based method. Also, the simulation results show the effectiveness of the proposed control design approach.     

非完整链式系统的输出跟踪控制——动态扩展线性化方法

针对非完整单链和多链系统,利用动态反馈线性化技术设计了输出跟踪控制器.证 明了当满足一定的条件时,通过选择适当的输出变量并利用动态反馈可使非完整链式系统实 现输入-输出完全线性化,从而可设计线性控制器跟踪期望的运动轨迹.最后以移动小车的跟 踪控制为例,通过仿真验证了文中方法的有效性.     

一类二阶非完整系统的镇定

研究一类二阶非完整系统的镇定问题. 通过状态和输入反馈变换将系统模型转换为二阶链式标准型, 并对标准型给出一种时变光滑指数镇定控制律. 所得结果应用于欠驱动平面刚体的镇定.     

车辆避障驾驶控制方法研究

受机器人基于人工势场的路径控制方法的启发,在吴镜开等提出方法的基础上,提出了车辆避障控制机制。定义了基于停车视距的车辆行驶动态目标位置;依据人工势场建模原理构建道路和障碍物势场;为了平滑车辆行驶路线,采用了贝塞尔（Bezier）曲线车辆轨迹拟合的方法;针对车辆系统是典型的非完整控制系统,将车辆运动学模型转换为链式系统模型,实现相对简化系统控制设计目的。仿真控制实验说明这种方法对车辆避障控制具有较好的轨迹跟踪效果和全局稳定性。     

变体飞行器链式平滑切换控制

针对变体飞行器在连续变形过程中的高度保持和姿态稳定问题,提出了一种平滑切换状态反馈控制器设计方法.建立了纵向运动的链式平滑切换系统模型,相比于传统的任意切换律和硬切换方案,所提出的模型能够更准确的反映变形过程的运动特性,且降低了设计的保守性.推导了链式平滑切换系统有限时间有界且具有鲁棒性能指标的充分条件,将增稳控制器设计转化为具有线性矩阵不等式组约束的优化问题.所设计的控制器虽然放宽了对系统渐近稳定性的要求,但能够保证系统状态在变形时间段内有界稳定,且兼顾了实际的舵偏响应.控制算例和非线性仿真验证了所提方法的有效性.     

Global stabilization and asymptotic tracking for a class of nonlinear systems by means of time‐varying feedback

A simple backstepping design scheme is proposed and sufficient conditions for non‐uniform in time global stabilization for parameterized systems by means of time‐varying feedback are established. Our methodology is applicable to a special class of systems that in general cannot be stabilized by static feedback and includes non‐holonomic systems in chained form. For this class of systems the main results on feedback stabilization enable us to derive sufficient conditions for the solvability of the tracking problem. Copyright © 2003 John Wiley & Sons, Ltd.     

Adaptive stabilization of uncertain nonholonomic systems by output feedback

The adaptive output feedback control strategy is presented for a class of nonholonomic systems in chained form with nonlinearity uncertainties. A new observer and a filter are introduced for the states and parameter estimation. The proposed control strategies guarantee the convergence of the closed-loop system. The simulation example demonstrates the efficiency of the proposed method.     

不确定非完整动力学系统的指数镇定

研究具有未知惯性参数非完整动力学系统的镇定问题,基于非连续变换和动力学方程的性质,设计出两类非线地指数镇定律－鲁棒控制和自适应控制律。将其用于一类移动机器人的位姿镇定,仿真结果验证了所提出控制方法的有效性。     

Robust adaptive neuro-fuzzy control of uncertain nonholonomic systems

In this paper, we present an adaptive neuro-fuzzy controller design for a class of uncertain nonholonomic systems in the perturbed chained form with unknown virtual control coefficients and strong drift nonlinearities. The robust adaptive neuro-fuzzy control laws are developed using state scaling and backstepping. Semiglobal uniform ultimate bound-edness of all the signals in the closed-loop are guaranteed, and the system states are proven to converge to a small neigh-borhood of zero. The control performance of the closed-loop system is guaranteed by appropriately choosing the design parameters. By using fuzzy logic approximation, the proposed control is free of control singularity problem. An adaptive control-based switching strategy is proposed to overcome the uncontrollability problem associated with x 0 (t 0 ) = 0.