New results for delay-dependent stability of linear systems with time-varying delay

The asymptotic stability problem for a class of linear systems with time-varying delays is studied using a generalized discretized Lyapunov functional approach. The kernel of the functional, which is a function of two variables, is chosen as piecewise linear. The conditions of the Lyapunov functional and its derivative are written in terms of linear matrix inequalities (LMIs). New delay-dependent stability criteria are proposed by simplifying the derived LMIs. Numerical examples show that the results obtained by these new criteria significantly improve the estimate of stability limit over the existing results in the literature.     

Dynamic Friction Control Using Dynamic Structured RFNN and Friction Parameter Estimator

A nonlinear dynamic friction control is dealt with using dynamic friction observer and intelligent control.The adaptive dynamic friction observer based on the LuGre friction is proposed to estimate the friction parameters and a directly immeasurable friction state variable.The dynamic structured Recurrent Fuzzy Neural Network(RFNN)is designed to give additional robustness to the control system under the presence of the friction model uncertainty.A proposed composite control scheme is applied to the position tracking control of the servo system.The performances of the proposed friction observer and the friction controller are demonstrated by simulation.     

Wind-induced coupled motion of tall buildings with varying square plan with height

One characteristic of many tall buildings is that their building shapes vary with height, implying that the distribution of their structural components may also vary with height. Response analyses have been conducted for tall buildings with square plans with height variations using high-frequency force balance data, focusing on comparing the total accelerations of the various building shapes based on the shapes themselves, and not on different natural frequencies. The variation trends of total accelerations are different between mass and rigidity center eccentricity, and the acceleration of the square model is the largest, and the differences among models increase with eccentricity. For the setback and tapered models, although the across-wind acceleration is larger than that of the square model, the along-wind and torsional accelerations are smaller than those of the square model, resulting in smaller total rms acceleration response. However, the increase in torsional response for the tapered and setback buildings when the offsets lie in the windward diagonal direction may enhance building occupants' awareness of the motion even if the total rms accelerations become small.     

基于FDO非线性预测方法的翼伞航迹跟踪控制

在翼伞系统的状态空间模型的基础上,分析了翼伞的归航轨迹,给出翼伞轨迹跟踪控制问题的数学描述.针对翼伞归航飞行过程中,受到较大的外干扰及不确定性影响,提出基于模糊干扰观测器(FDO)的非线性预测控制策略,设计了翼伞归航系统航迹跟踪控制器.通过仿真试验,表明该飞控系统具有良好鲁棒特性和抗干扰特性.     

直线加减速优化算法在陶瓷施釉机械手中的应用

控制系统的位置精度和运行时间是衡量施釉机器手好坏的主要性能指标,加减速模式特别是减速模式对其性能有着重要的影响。本文针对在施釉机械手运动过程的最后减速阶段仍会出现低速运行的＂尾巴＂现象,提出了一种新的实时加减速优化算法,并给出了试验结果。结果表明,该算法可有效消除减速过程中的低速运行时间段,从而提高施釉机械手的加工精度和效率。     

Target Tracking Algorithm Using Finite-time Convergence Smooth Second-order Sliding Mode Controller for Mobile Robots

Target tracking control for wheeled mobile robot (WMR) need resolve the problems of kinematics model and tracking algorithm.High-order sliding mode control is a valid method used in the nonlinear tracking control system,which can eliminate the chattering of sliding mode control.Currently there lacks the research of robustness and uncertain factors for high-order sliding mode control.To address the fast convergence and robustness problems of tracking target,the tracking mathematical model of WMR and the target is derived.Based on the finite-time convergence theory and second order sliding mode method,a nonlinear tracking algorithm is designed which guarantees that WMR can catch the target in finite time.At the same time an observer is applied to substitute the uncertain acceleration of the target,then a smooth nonlinear tracking algorithm is proposed.Based on Lyapunov stability theory and finite-time convergence,a finite time convergent smooth second order sliding mode controller and a target tracking algorithm are designed by using second order sliding mode method.The simulation results verified that WMR can catch up the target quickly and reduce the control discontinuity of the velocity of WMR.     

Luenberger速度观测器在同步运动控制中的应用

根据Luenberger观测器原理,在运动控制系统中建立速度观测器,并使用观测速度作为同步运动运动控制系统的闭环控制反馈信号,有效解决由传感器引入的相位延迟和噪声对系统性能产生的影响.通过在Simulink中对系统建模仿真,验证了此同步运动控制系统具有更高的信号响应能力和抗扰动性能.最后,在以TI公司DSP6722为核心的硬件平台上实现速度观测器算法.实验结果表明,Luenberger观测器可以较为精确地观测速度信号,为同步运动控制系统性能提供可靠保障.     

一种二阶系统最优Q滤波器DOB设计方法研究

对一种新的系统化的最优Q滤波器干扰观测器(Disturbance Observer DOB)的参数设计方法进行研究,它用来校正二阶系统的外界干扰输入和一定范围内的系统不确定性.基于控制系统结构的变形、Q滤波器特性的分析和综合、最优参数和偏好参数的选取以及超前补偿器的设计,这种方法可以直接设计出一组相对于干扰-输出传递函数特性的最接近理论最优解的实际最优控制器参数.应用这种最优Q滤波器DOB,对于系统不确定性的适应和对外界干扰的抑制的要求都能很好的满足,并且通过系统仿真更验证了这一设计方法.     

基于发动机四参数的轮式越野车换挡加速时间计算

在只有发动机最大功率、最大扭矩及其对应转速等四大参数的情况下,引入限定车速系数,以可能的最短总加速时间为原则确定换挡车速点;以基于发动机四参数的外特性模型为基础建立轮式越野车加速度模型,进而确定等加速度车速;由加速度模型建立不含积分运算的各档加速时间计算公式;考虑每次换挡所耗时间,推导换挡加速时间计算模型。利用Matlab对某轮式越野车等加速度车速、换挡车速、加速度和换挡加速时间进行设计计算,实例结果表明,该方法易于在Matlab中用程序实现,计算精度也有所提高。     

交流伺服系统的鲁棒性研究

干扰是影响系统性能的主要因素,利用干扰观测器可对交流伺服系统中由负载改变、工作环境变化和建模误差等产生的干扰进行补偿。工作时先在线辨识出系统的模型参数,将干扰观测器的名义模型自动调整为辨识值,再进行所需的控制。研究结果表明,采用干扰观测器结合模型参数在线辨识的交流伺服系统具有较强的鲁棒性。