Finite-time optimal tracking control for a class of nonlinear systems with prescribed performance

In this paper, a finite-time optimal tracking control scheme based on integral reinforcement learning is developed for partially unknown nonlinear systems. In order to realize the prescribed performance, the original system is transformed into an equivalent unconstrained system so as to a composite system is constructed. Subsequently, a modified nonlinear quadratic performance function containing the auxiliary tracking error is designed. Furthermore, the technique of experience replay is used to update the critic neural network, which eliminates the persistent of excitation condition in traditional optimal methods. By combining the prescribed performance control with the finite-time optimization control technique, the tracking error is driven to a desired performance in finite time. Consequently, it has been shown that all signals in the partially unknown nonlinear system are semiglobally practical finite-time stable by stability analysis. Finally, the provided comparative simulation results verify the effectiveness of the developed control scheme.     

The Effect of the Rotary Steerable Spindle Structure Parameters on the Characteristics of Cantilever Bearing

Journal of Failure Analysis and Prevention - In point-the-bit rotary steerable drilling system, the internal and outer diameter of the spindles and the fillet radius of the shaft shoulder have a...     

Synthesis of ultrathin semicircle-shaped copper nanowires in ethanol solution for low haze flexible transparent conductors

Nano Research - Copper nanowires (CuNWs) are becoming an indispensable item for next-generation transparent optical devices due to their excellent conductivity and transparency. In this work,...     

智能车竞赛中道路的视频识别方案

视频信号的的采集和处理是一个复杂的过程,这需要程序设计者了解视频信号的构成,充分利用复合视频信号中的各种同步信息作为视频信号采集的控制信号,从而完成信号的采集。     

基于罚函数的解析目标分流法计算特性分析

为了在复杂产品早期开发阶段更好的使用解析目标分流法(ATC),分析了基于不同罚函数的ATC方法的计算特性.给出了ATC方法的一般公式,比较了3种ATC方法的优缺点,以常用的几何规划算例为例,研究了初值、初始罚参数、收敛准则等因素对计算精度和计算花费的影响.计算结果表明,ATC是一种稳定性好、计算效率高的多学科设计优化(MDO)方法,并且基于增广拉格拉日函数的ATC方法的总体性能比其它两种方法要好一些.     

单磁悬浮系统的纵向解耦控制研究

磁悬浮系统是复杂的强耦合系统,研究中未充分考虑轨道的弹性形变,会造成磁浮列车和轨道之间产生耦合振动的现象,而考虑这一因素对系统的影响无疑增加了研究的难度;为了便于问题的求解,采用非线性系统理论解耦的方法,对单电磁铁悬浮系统进行纵向解耦控制,并对解耦后的子系统进行极点配置使其满足要求的性能指标;仿真结果表明该方法有效地使复杂问题简单化,并且能够实现系统的全局稳定和良好的动态性能.     

一种可行的可用性测试过程

文章综述用户模型法、用户调查法、专家评审法和观察法4类可用性测试方法,根据可用性测试的经验,总结出一套合理实用的可用性测试过程,使得可用性测试的效率高、代价低,尽可能发现更多的可用性问题;提出在程序设计类课程的教学中,应适当向学生介绍可用性测试的方法和过程,以培养学生对自己开发的软件系统进行可用性测试的能力。