Uniting Local and Global Controllers with Robustness to Vanishing Noise

We consider control systems for which we know two stabilizing controllers. One is globally asymptotically stabilizing, the other one is only locally asymptotically stabilizing but for some reason we insist on using it in a neighborhood of the origin. We look for a uniting control law being equal to the local feedback on a neighborhood of the origin, equal to the global one outside of a larger neighborhood and being a globally stabilizing controller. We study several solutions based on continuous, discontinuous, hybrid, time-varying controllers. One criterion of the selection of a controller is the robustness of the stability to vanishing noise. This leads us in particular to consider a kind of generalization of Krasovskii trajectories for hybrid systems. Date received: November 29, 1999. Date revised: August 7, 2000.     

一类具有不确定性的相似组合系统的鲁棒输出反馈镇定

讨论受非线性扰动的线性相似子系统经非线性互联而形成的组合大系统（相似组合系统）的鲁棒输出反馈镇定问题,这类相似组合系统可以用结构类似于“砰砰”控制的分散输出反馈控制器鲁棒渐近镇定。     

具有有界摄动的非线性系统鲁棒控制

针对不确定性由增益有界的摄动函数表示的非线性系统,讨论了状态反馈鲁棒镇定问题,结果表明,如果所讨论的系统具有鲁棒最小相位特性,且其标称系统相对阶为1,则反馈控制可以通过构造满足本文引理条件的正定函数得到。     

一类具有有界控制器的多重时变滞后系统的指数稳定性

考虑了一类具有多重时变滞后和有界控制器的不确定动力系统的鲁棒指数稳定性问题.匹配一个无记忆的控制器,确保存在一个吸收域.我们所考虑的这类系统的解收敛于一个给定的球.球的半径和指数收敛率可以任意选择.     

Limitations of nonlinear discrete periodic control for disturbance attenuation and robust stabilization

This paper presents a performance analysis of nonlinear periodically time-varying discrete controllers acting upon a linear time-invariant discrete plant. Time-invariant controllers are distinguished from strictly periodically time-varying controllers. For a given nonlinear periodic controller, a time-invariant controller is constructed. Necessary and sufficient conditions are given under which the time-invariant controller gives strictly better control performance than the time-invariant controller from which it was obtained, for the attenuation of l_p exogenous disturbances and the robust stabilization of l_p unstructured perturbations, for all p[1,∞].     

A functional equations approach to nonlinear discrete-time feedback stabilization through pole-placement

The present work proposes a new approach to the nonlinear discrete-time feedback stabilization problem with pole-placement. The problem's formulation is realized through a system of nonlinear functional equations and a rather general set of necessary and sufficient conditions for solvability is derived. Using tools from functional equations theory, one can prove that the solution to the above system of nonlinear functional equations is locally analytic, and an easily programmable series solution method can be developed. Under a simultaneous implementation of a nonlinear coordinate transformation and a nonlinear discrete-time state feedback control law that are both computed through the solution of the system of nonlinear functional equations, the feedback stabilization with pole-placement design objective can be attained under rather general conditions. The key idea of the proposed single-step design approach is to bypass the intermediate step of transforming the original system into a linear controllable one with an external reference input associated with the classical exact feedback linearization approach. However, since the proposed method does not involve an external reference input, it cannot meet other control objectives such as trajectory tracking and model matching.     

STABILIZATION OF A CLASS OF NONLINEAR NON‐MINIMUM PHASE SYSTEMS

This paper tackles the problem of stabilization of a class of non‐minimum phase nonlinear systems which have zero dynamics with an eigenvalue zero of multiplicity 2. By adding some new terms, called cross terms, we are able to generalize the concept of the Lyapunov function with a homogeneous derivative along the trajectory, which was introduced in [4], to produce a suitable Lyapunov function. The Lyapunov function assures that the stability of an approximate system, which consists of some lower order terms of a nonlinear system with an eigenvalue zero of multiplicity 2, implies the stability of the whole system. Applying these to non‐minimum phase zero dynamics of nonlinear systems with such a center, a sufficient condition and a design method of state feedback control are obtained for stabilizing the systems.     

南水北调东线工程沿线城市尾水处理方案比选

以洪泽县为例,综合运用水文学和生态学等理论和方法,研究南水北调东线工程沿线城市尾水处理方案的选择,最终确定蓄水塘-廊道-兼性塘-表面流湿地组合的尾水处理方案,并建议将处理工艺与景观建设相结合,建成集生态、景观、休闲、科教等功能于一体的综合性示范工程。     

机载雷达天线空域稳定测试系统的设计

为确保空域稳定回路稳定工作,使机载雷达天线锁定的空域不随飞机空中姿态变化而变化,需要设计一个地面测试系统,检测回路是否处于稳定工作状态。在分析了空域稳定回路功能和性能测试基本要求基础上,设计了天线空域稳定测试系统,给出了测试系统硬件、软件实现方案。采用计算机控制及自动测试技术,实现了测试自动化,并能对故障精准定位。实际应用结果表明,测试系统技术先进、操作简单、易于维护、运行稳定,取得了显著的军事和经济效益。