一类关于不确定性机器人的鲁棒控制策略1)

基于计算力矩结构,研究参数和结构不确定的机器人轨迹跟踪的鲁棒控制策略.其特点是利用了机器人不确定动力学的集中包络函数,在该包络函数已知的情况下,设计的非线性连续补偿控制律能够有效消除系统的不确定性影响,保证系统达到三种不同的稳定性结果.另外,在该包络函数参数未知时,还设计了一个新颖的在线辨识器,可保证系统指数意义下的渐近收敛或一致有界.     

基于滑模变结构的空间机器人神经网络跟踪控制

研究了在无需模型估计值的情况下不确定空间机器人轨迹跟踪问题,提出了滑模变结构的神经网络控制方案.首先基于Lyapunov理论设计了一种径向基函数（RBF）神经网络控制器来补偿系统中的未知非线性,该神经控制器能够保证闭环系统的稳定性,而通过利用饱和函数把神经网络和滑模控制结合起来的控制器来不仅可以进一步削弱滑模控制输入的抖振,且当神经网络控制器无效时仍能保证系统鲁棒性.仿真结果证明了该控制器能在初期及强干扰情况下均能达到较好的控制效果.     

基于广义双曲正切模型的机器人鲁棒模糊自适应控制

利用广义模糊双曲正切模型的全局逼近特点,设计一种模糊自适应控制器用于机器人轨迹跟踪控制.广义双曲正切模型利用输入变量的平移能以任意精度逼近系统的不确定动态.对于系统不确定外界干扰和模糊系统的逼近误差,通过求解一个线性矩阵不等式来保证闭环系统的鲁棒稳定性.对比传统的模糊基函数,在保证系统跟踪精度的前提下,双曲正切模糊基函数的自适应调整参数大大减少,仿真表明该控制算法具有较强的鲁棒性能和较好的跟踪性能.     

不确定机器人的神经网络轨迹控制

针对不确定机器人的轨迹跟踪问题,提出了一种基于自适应神经网络的控制方案.对于系统中的各种未知非线性,通过RBF神经网络和变结构光滑集成的控制器来自适应学习并且补偿,这种控制器克服了局部泛化网络的不足,提高了控制精度及其收敛速度.而且在考虑神经网络失效的情况下,仍能保证系统具有良好的鲁棒性.网络权重的自适应修正规则基于Lyapunov函数方法得到,它保证了跟踪误差的全局渐进稳定性.试验结果证明了这种控制算法的有效性.     

水下机器人姿态H∞/H2鲁棒控制实验研究

设计安装自动平衡装置作为物理仿真系统对水下机器人姿态控制进行实验研究.给出了实验系统的结构.结合具体系统设计了H∞/H2鲁棒控制器,分析了调节设计参数对系统性能的影响;结合实际参数不确定范围确定了合理的设计参数范围;进一步结合实际调试中的具体问题确定了适当的参数选取.研究表明采用H∞/H2鲁棒控制可以保证系统在较大范围的参数变化时,保持稳定并对随机干扰有较强的抑制.研究结果可供实际水下机器人控制系统研制作参考.     

自行车机器人系统的稳定滑模控制

基于拉格朗日方法建立自行车机器人动力学模型,针对自行车机器人这一非线性欠驱动系统,利用稳定滑模控制算法实现系统的稳定.该方法首先从各个子系统中取出一个变量组合成一个中间变量;然后从该中间变量出发构造滑模函数,从滑模控制器设计的角度求取控制量,保证中间变量在有限时间内收敛到平衡点,从而保证系统状态收敛到收敛域内.该方法能够保证自行车机器人系统的稳定性,并在仿真实验中得到了验证.     

空间机器人分布式滑模变结构控制方法

针对空间机器人的动力学特性和星载控制系统的结构特点,分别基于干扰上确界和比例切换,设计了2种分布式滑模变结构控制方法,以实现在存在不确定干扰和关节摩擦力矩情况下基座姿态和关节运动的综合控制.首先给出了空间机器人的动力学模型和关节低速摩擦力矩模型,并以两自由度空间机器人为例,介绍了2种分布式滑模变结构控制方法的推导过程.通过仿真实验,对2种控制方法进行了对比,结果表明分布式变结构控制方法在简化算法的同时,能够保证系统控制性能,并对干扰和参数变化具有较强的鲁棒性.     

执行器受限机器人的鲁棒输出调节

针对实际的控制系统中执行器受限的问题,研究了机器人存在不确定结构参数及外界干扰时的输出调节问题.基于李雅普诺夫稳定性理论,通过在构造存储函数的过程中引入双曲正切函数和适当的辅助函数,设计了一种有界的鲁棒控制器.所提出的控制器不保证了闭环系统的鲁棒稳定性,同时也达到了从干扰信号到跟踪误差评价信号所定义的L2增益性能指标γ,即保证了干扰抑制的有效性.最后,由两连杆机器人进行的仿真结果验证了该控制器的可行性.     

柔性结构机器人优化设计

本文提出了柔性结构机器人优化设计问题.将机器人结构重量函数和弹性变形能函数采用线性加权组合成多目标函数,并取精度、应力、驱动力矩等限制条件作为约束方程进行优化.其优化解确定了具有一定结构柔性和最轻结构重量的柔性结构机器人各臂的最佳横截面相对几何尺寸参数.     

一种高效能的机器人模糊控制方案

本文提出一种高效能的模糊控制方案,来提高机器人当存在摩擦力和负载等不确定因素 时以及动力学参数变化时的系统响应特性.该控制方案是由一个模糊逻辑(FL)控制器(主 控制器)和一个传统的微分(D)控制器(辅助控制器)所构成.FL控制器用来提高系统的瞬 态特性和稳态精度,D控制器用来保证系统的稳定性.在这一控制方案基础上,获得理想控 制特性的主要思想是研究和调整语言变量的隶属度函数.模拟结果表明了这一控制方案的 有效性和鲁棒性.此外,这一控制方案具有结构简单且易于实现的优点.     

新一类的机器人鲁棒跟踪控制策略

本文提出了一类基于计算力矩结构的变增益鲁棒控制策略，用于参数不确定性机器人的轨迹跟踪．其特点是利用了机器人动力学的一种特殊的参数变量分离方法，只需知道一个集中的系统不确定性参数，能够有效的消除参数误差带来的不确定性影响，最后保证系统达到３种不同的稳定性结果．另外，在该参数未知时，我们还设计了一个简单的在线辨识器，可保证系统全局的收敛．理论和仿真，均证明了其可靠性和有效性．     

Robust control of nonlinear systems in the presence of unknown exogenous dynamics

A robust control is designed for a class of uncertain systems, the proposed control is distinct and novel in that it does not require any information of a bounding function on nonlinear uncertainties in the system. Instead, the uncertainties to be compensated for are generated by an exogenous system whose dynamics are either completely unknown or partially unknown. The only requirements on the exogenous system are that its unknown dynamics are bounded by a known function and that its output is bounded. The proposed robust control is based on a nonlinear observer that estimates the uncertainties. It is shown that, under different sets of conditions, local, semiglobal, or global stability of uniform ultimate boundedness or asymptotic stability can be achieved.     

不依赖模型的机器人鲁棒自适应跟踪控制(英)

提出了一种新颖的鲁棒自适应控制策略，用于不确定性机器人的轨迹跟踪．它不需要任何模型知识，唯一需了解的是系统的阶数和输出的位置及速度状态。理论和仿真均证明，系统的不确定性诸如摩擦力、外部扰动及未建模动力学带来的不确定性影响，均可被设计的控制律补偿，最后可保证全局指数收敛或全局一致最后有界的结果．另外，本文还给出了跟踪误差的暂态测量．     

Robot robust path tracking

A new discontinuous robust control law for a rigid manipulator with bounded parameter uncertainties to track a desired trajectory, is presented. Global exponential stability is proved by the use of a natural Lyapunov function based on a transformation of the manipulator's differential equation due to Slotine and Li [2]. Convergence is to a sliding mode along which the tracking error is reduced at an arbitrary exponential rate. It is also shown how adaptation of bounds on uncertainties, and parameter adaptation, can be incorporated. For a continuous approximation of the discontinuous control law,practical stability (essentially, global uniform ultimate boundedness) of the tracking error is proved. Simulation results for the continuous control law exhibit excellent robust tracking.     

ON THE LYAPUNOV APPROACH TO ROBUST STABILIZATION OF UNCERTAIN NONLINEAR SYSTEMS

In the Lyapunov approach employed in this paper, known in the literature as Lyapunov control, or min-max control, robust, global uniform asymptotic stability is achieved by a discontinuous control law which ensures that the Lyapunov derivative is negative despite bounded uncertainty. For that, it is assumed that the uncertainties satisfy certain matching conditions, and that a Lyapunov function for the nominal plant is available. To obtain lower control magnitudes, this paper develops control laws which counter the uncertainties on a component-wise basis, rather than the usual normic one. Both the basic discontinuous control law, which is proved to provide robust global uniform asymptotic stability, and a continuous app roximation, which is proved to ensure global uniform ultimate boundedness, are derived. Application to model following is given. We adapt recent results on robust quadratic stabilization of nominally linear time-invariant plants subjected to nonlinear, bo unded and unmatched uncertain perturbations, to extend our results to this important class of systems; this is illustrated by two examples.     

Robust adaptive control for interval time-delay systems

1 Introduction The problem of time-delay is commonly encountered in various engineering systems, such as electric, pneumatic and hydraulic networks, long transmission lines, etc., and it is also a great source of systems instability and poor perfor- mance. During the last decades, we have seen an increasing interest for the control of this class of systems and many results have reported in the literature [1～5]. On the other hand, it has been recognized that nonlinear uncertainties are unavoid…     

Robust dynamic surface trajectory tracking control for a quadrotor UAV via extended state observer

In this paper, we present an extended state observer–based robust dynamic surface trajectory tracking controller for a quadrotor unmanned aerial vehicle subject to parametric uncertainties and external disturbances. First, the original cascaded dynamics of a quadrotor unmanned aerial vehicle is formulated in a strict form with lumped disturbances to facilitate the backstepping design. Second, based on the separate outer‐ and inner‐loop control methodologies, the extended state observers are constructed to online estimate the unmeasurable velocity states and lumped disturbances existed in translational and rotational dynamics, respectively. Third, to overcome the problem of “explosion of complexity” inherent in backstepping control, the technique of dynamic surface control is utilized for trajectory tracking and attitude stabilization, and with the velocity and disturbance estimates incorporated into the dynamic surface control, a robust dynamic surface flight controller that guarantees asymptotic tracking in the presence of lumped disturbances is synthesized. In addition, the stability analysis is given, showing that the present robust controller can ensure the ultimate boundedness of all signals in the closed‐loop system and make the tracking errors arbitrarily small. Finally, comparisons and extensive simulations under different flight scenarios are performed to validate the effectiveness and superiority of the proposed scheme in accurate tracking performance and enhanced antidisturbance capability.     

Exponential ultimate boundedness and stability of stochastic differential equations with impulese

The paper mainly studies globally pth moment exponentially ultimate boundedness and pth moment exponential stability of impulsive stochastic functional differential equations. By using the Lyapunov direct method of Razumikhin-type condition and the principle of comparison, some sufficient conditions for globally pth moment exponentially ultimate boundedness and globally pth moment exponential stability are presented. Theorems require the linear coefficients of the upper bound of Lyapunov differential operators are time-varying functions; this generalizes the previous results. When the time delay is not considered in the system, a unified criterion is given to achieve boundedness and stability when the system is disturbed by stabilizing impulse and destabilizing impulse. It shows that the stochastic differential equation may be unbounded or unstable, and it can be bounded or stable by adding appropriate impulsive perturbation. Finally, we use two examples to illustrate the validity of our results.     

Boundedness and stability analysis for impulsive stochastic differential equations driven by G-Brownian motion

In this article, the pth moment globally exponential ultimate boundedness, pth moment globally exponential stability, quasi sure globally exponential boundedness and quasi sure globally exponential stability are investigated for impulsive stochastic differential equations driven by G-Brownian motion. Using G-Lyapunov function methods and inequality techniques, some sufficient conditions are derived for the boundedness and stability. Comparing with the existing methods, the obtained results allow the corresponding impulse-free systems to be unstable and unbounded. An example is provided to show the effectiveness of the theoretical results.