液压机械传动多领域虚拟样机加速性仿真研究

液压机械无级传动是一种新型的无级传动形式,对这种传动形式的研究是非常有价值的.本文建立了液压机械无级传动系统的多领域虚拟样机仿真模型,对其加速性进行了仿真分析,得到了液压元件排量变化速率对车辆加速性的影响规律.仿真研究结果为液压机械无级传动系统控制策略的制定和工程应用提供了重要的理论参考.     

Variable structure controllers for unstable processes

A variable structure control (VSC) method for unstable industrial processes is proposed. The proposed control method is able to provide a highly satisfactory system performance and to tackle with robustness issues of the processes in the presence of uncertainties. An ITAE-based numerical tuning algorithm for acquiring optimal control parameters, and a direct auto-tuning mechanism for the proposed controller are also provided. The performance of the proposed VSC method is illustrated on some unstable process models including a continuous stirred tank reactor (CSTR), in order to show its effectiveness, validity and feasibility.     

Variable Structure Control with chattering elimination and guaranteed stability for a generalized T-S model

In this paper, a fuzzy based Variable Structure Control (VSC) with guaranteed stability is presented. The main objective is to obtain an improved performance of highly non-linear unstable systems. The main contribution of this work is that, firstly, new functions for chattering reduction and error convergence without sacrificing invariant properties are proposed, which is considered the main drawback of the VSC control. Secondly, the global stability of the controlled system is guaranteed.The well known weighting parameters approach, is used in this paper to optimize local and global approximation and modeling capability of T-S fuzzy model.A one link robot is chosen as a nonlinear unstable system to evaluate the robustness, effectiveness and remarkable performance of optimization approach and the high accuracy obtained in approximating nonlinear systems in comparison with the original T-S model. Simulation results indicate the potential and generality of the algorithm. The application of the proposed FLC-VSC shows that both alleviation of chattering and robust performance are achieved with the proposed FLC-VSC controller. The effectiveness of the proposed controller is proven infront of disturbances and noise effects.     

基于全可变气门汽油机进气量测量和控制问题研究

基于全可变气门运动机构的气门参数控制燃烧技术是改善传统SI汽油机燃油经济性,提高动力性和降低排放的最为有效的途径之。但是这也对发动机进气量的测量和控制提出了更高的要求。本文通过仿真和试验相结合的方法,对基于全可变气门机构汽油机进气量测量和控制问题进行了探讨和研究。     

宏程序在数控车削加工中的应用

用户宏指令编程是FANUC系统所提供的一种先进的编程方法,它使用变量代替程序中的功能代码或地址值进行编程,使数控程序具有通用性和灵活性并简化了数控编程。本文以FANUC0i系统为例,给出了常用的非圆曲线的宏程序编制方法。     

再入飞行器变结构姿态控制律设计与仿真

研究飞行器再入问题,以美国X-34技术验证机为对象,提出了一种再入飞行器变结构姿态控制算法。为提高姿态控制的精度,通过设计内外双环控制器,并选择适当的趋近律和符号函数连续化方法来解决由于变结构控制带来的抖振问题。同时基于X-34反作用控制系统(RCS)配置方案给出了一种RCS控制模式。由于RLV存在两套姿态控制执行机构与气动舵面,提出了一种基于动压调节的混合控制策略。最后通过Matlab/Simulink仿真计算验证了在标称状态与加入扰动时的控制算法的有效性,具有良好的跟踪性能和强鲁棒性。     

Neural networks in process life cycle profit modelling

Changes in operational environment of the process industry such as decreasing selling prices, increased competition between companies and new legislation, set requirements for performance and effectiveness of the industrial production lines and processes. For the basis of this study, a life cycle profit (LCP) model of a pulp process was constructed using different kind of process information including chemical consumptions and production levels of material and energy flows in unit processes. However, all the information needed in the creation of relevant LCP model was not directly provided by information systems of the plant. In this study, neural networks was used to model pulp bleaching process and fill out missing information and furthermore to create estimators for the alkaline chemical consumption. A data-based modelling approach was applied using an example, where factors affecting the sodium hydroxide consumption in the bleaching stage were solved. The results showed that raw process data can be refined into new valuable information using computational methods and moreover to improve the accuracy of life cycle profit models.     

Design of variable structure control for fuzzy nonlinear systems

In this paper, the variable structure control problem is presented for Takagi–Sugeno fuzzy systems with uncertainties and external disturbances. The sliding surfaces for the T–S fuzzy system are proposed by using a Lyapunov function and a fuzzy Lyapunov function, respectively. And we design the variable structure controllers such that the global T–S fuzzy system confined on the sliding surfaces is asymptotically stable. Two examples are given to illustrate the effectiveness of our proposed methods.     

变精度模糊粗糙集的一种定义

模糊粗糙集模型同经典粗糙集模型类似,容易受到噪音数据的影响.针对该问题,受变精度粗糙集模型的启发,提出了变精度模糊粗糙集的概念.针对现有变精度模糊粗糙集模型尚不能满足一些基本性质的缺陷,重新定义了模糊近似空间中某一模糊集的β-下近似和β-上近似,该定义方式能够满足上述的基本性质.     

一种离散时间系统变结构控制的新方法

研究离散时间系统变结构控制问题,提出一种新的离散变结构趋近律.利用该趋近律设计的离散变结构控制器,不仅能大幅度削弱抖振,使系统运动最终趋干原点不存在稳态振荡,而且可使系统的准滑动模态保持步步穿越切换面的基本属性,有效地改善了控制品质,提高了系统的鲁棒性.仿真结果验证了该方法的有效性与合理性.