增益衰减对预失真算法的性能优化

在放大器功率增益对预失真线性化性能的影响问题的研究中,线性化技术需要更大的线性工作区域和更高的线性化性能.为提高变压器的性能,提出一种新的预失真算法优化方法,调整预失真器的应用模式,通过衰减输出功率增益扩展线性工作区域,并能实现较好的线性化性能.实验验证了上述优化方法的有效性.合理选择实际输出功率增益,利用增益衰减优化预失真算法,可以增大预失真放大器的线性工作区域,提升变压器的线性化性能.改进的优化方法为预失真技术的研究和应用提供了科学依据.     

空间电磁对接控制问题

航天器空间电磁对接能避免诸如推进剂消耗、羽流污染和对接冲击等现有基于推力器对接所固有的缺陷,应用前景广阔.空间电磁对接控制目前国内外还没有有效研究,论文主要针对此问题开展初步研究工作.论文首先重点分析空间电磁对接特性及其主要控制问题,然后采用反馈线性化方法对地面二维电磁对接控制模型进行线性化处理、以及基于线性化模型应用Kalman滤波方法估计电磁对接运动状态,最后采用二阶稳定性方法设计控制律并进行仿真分析.理论研究和仿真分析表明:航天器空间电磁对接是可行的,电磁对接非线性模型可以采用反馈线性化方法实现精确线性化,基于线性化模型的二阶稳定性方法满足控制律设计要求.     

三自由度直升机模型跟踪控制

针对三自由度直升机模型中存在的轴间强耦合和非线性的特性,采用系统分解与输入-状态反馈的线性化方法,对非线性耦合模型进行精确线性化处理,实现了系统解耦与线性化,并简化了控制器设计结构.首先应用拉格朗日方法对系统进行力学仿真分析.通过建立直升机的精确模型,将模型分解为两个子系统,利用状态线性化,得到简单的线性系统.分别采用无静差跟踪方法与伺服控制方法设计子系统控制器,改善了系统性能,实现了对参考输入的无静差跟踪.仿真表明,方法提高了系统稳定性,轨迹跟踪效果好.     

牛顿迭代法在智能仪表线性化中的应用

利用现有的解析式,采用牛顿选代法可以实现线性化处理.详细介绍温度、压力线性化的具体算法及实现步骤.     

基于逆系统方法的广义非线性系统控制及电力系统应用

对一般广义非线性系统的反馈线性化问题,通过将代数变量视为虚拟输入,给出了构造性递归求逆算法,实现了系统的精确反馈线性化.作为该算法的应用,讨论了带有非线性负荷的三节点电力系统的励磁控制问题,设计了非线性励磁控制器.仿真结果表明了方法的有效性.     

多功能转换器在气敏传感器线性化电路中的应用

介绍一种利用多功能转换器实现气敏传感器非线性特性的线性化补偿的原理电路及实验结果.该线性化电路具有测量范围宽,线性精度高且易于实现等优点.     

混合励磁电机系统输入输出解耦和线性化

讨论混合励磁电机系统的输入输出解耦和线性化问题.根据机电动力学原理,导出了混合励磁电机系统在与转子同步旋转的d-q坐标系中的动态方程.应用非线性系统几何理论,通过非线性状态反馈和坐标变换,实现了混合励磁电机系统的输入输出解耦控制和完全线性化.将原系统分解为3个线性子系统：d轴磁链子系统、q轴磁链子系统和转速子系统.仿真结果表明,基于输入输出线性化控制设计的混合励磁电机控制系统具有良好的动态性能.     

基于加权最小二乘的卡尔曼滤波算法

为了将卡尔曼滤波(KF)应用于非线性系统中,利用了离散采样点将非线性模型线性化.通过加权最小二乘原理.得到近似的线性化模型,再将KF算法应用于这个线性模型中.结果表明,加权最小二乘与KF结合的方法在非线性模型中的计算结果同扩展卡尔曼滤波(EKF)算法接近,且不需要EKF那样求偏导就能很容易地应用到非线性系统中.这种方法实现容易,预测可靠,具有实际应用的价值.     

基于微分几何的风力发电机组恒功率控制

当风速超过额定值时, 可以通过降低风力机的转速实现恒功率控制从而避免使用复杂的变桨距机构, 本文基于微分几何理论设计了非线性控制器, 实现了变速风力发电机组的恒功率控制. 首先, 分析了风力机的空气动力学特性, 这是所提出的恒功率控制方法的理论依据; 然后, 通过微分几何反馈线性化变换, 将风力机的非线性模型全局线性化; 最后, 基于新的线性化模型设计了非线性控制器, 实现了变速风力机的全局精确线性化控制. 仿真结果表明, 所提出的控制方法在风速大范围变化的情况下能有效的实现变速风力发电机组额定风速以上的恒功率控制.     

用微机技术解决测温用热敏电阻线性化与互换性方法的讨论

众所周知,妨碍热敏电阻在测温中大量使用的主要问题是热敏电阻特性的非线性,其次是互换性差。本文重点讨论如何应用微机技术实现热敏电阻特性线性化的二方面工作。一是实现特性数字化所常用的线路和转换器,二是实现线性化的程序,介绍了常用的二种方法。     

Comparative study on linearized robot models

For representing the input—output behaviour of a robot manipulator by a linear time-invariant model, four direct linearization schemes are: (i) state linearization, (ii) linearization based on an identification method, (iii) linearization based on neglecting velocity-dependent and gravity terms and (iv) linearization based on neglecting the velocity-dependent term only (rate linearization). In order to make an appropriate choice of linear model for the development of real-time control, these schemes are extensively studied in this paper. It is shown that the rate linearization method leads to a satisfactory tradeoff between computation, accuracy, and stability. In the case of high velocity motions, a combination of state linearization and rate linearization is proposed.     

A neural approach for control of nonlinear systems with feedback linearization.

Several schemes for feedback linearization using neural networks have been investigated and compared. Then an approach to design a neurocontroller in the sense of feedback linearization is introduced. The contents include: (1) full input-output linearization when a system has relative degree n; (2) partial input-output linearization when a system has relative degree r (r相似文献   

New results on non-regular linearization of non-linear systems

This paper presents some new results on non-regular linearization of non-linear systems. Based on a normal form and a non-regular linearization technique developed recently, the paper first provides a set of calculating formulas for the linearization procedure. As an application, the linearization of bilinear systems is investigated. Then, it presents easily verifiable sufficient conditions for the global (semi-global) (approximate) linearization. Finally, an estimate of the region of attraction for the kth degree approximately linearized systems with state feedback control is given, which illustrates one of the advantages of the approximate linearization.     

近似线性化方法综述

回顾了精确线性化方法及目前存在的主要问题,讨论了基于平衡流型和工作点邻域的状态方程近似线性化问题,研究了输入输出近似线性化在自理非最小相位或不可控非线性问题时的作用。最后对未来的研究方向进行了探讨。     

Cascaded feedback linearization and its application to stabilization of nonholonomic systems

In this paper, a new cascaded feedback linearization problem is formulated and a set of conditions on the cascaded feedback linearizability are established for a class of two-input affine nonlinear systems. The proposed cascaded feedback linearization method enlarges the classes of nonlinear systems which can be dealt with using the feedback linearization technique. In particular, the proposed design can be applied to address the feedback stabilization problem for a few classes of nonlinear systems which have uncontrollable linearization and do not satisfy the standard feedback linearization conditions. As an illustrative application, the proposed cascade feedback linearization concept is used to solve the feedback stabilization problem of nonholonomic systems within the framework of continuously differentiable state feedback control. Simulation results are provided to illustrate the proposed method.     

An equivalent linearization method for nonlinear Van der Pol oscillator subjected to random vibration using orthogonal functions

This paper deals with the idea of the orthogonal functions in the equivalent linearization of the nonlinear systems. Block Pulse (BP) function gives effective tools to approximate complex problems. The aim of this work is on using properties of the BP function as an orthogonal function in process of linearization. The BP functions have been used to propose an equivalent linearization method in the time domain to determine the unknown linearization coefficients. The accuracy of the proposed method compared with the other equivalent linearization approaches, including the regulation linearization and the dual criterion linearization methods. This study exploited the nonlinear Van der Pol oscillator system under stationary random excitation to demonstrate the feasibility of the proposed method. The validity of the analytical method is verified by applying different values of nonlinearity and intensity of excitation. Besides, by comparing the mean square responses and frequency response functions of the linearized systems for a wide range of nonlinearity depicted the present method is in agreement with other methods.     

Linearized dynamic models for trajectory control of robot manipulators

To make an appropriate choice of linear model for the development of real-time control of robot manipulators, four direct linearization schemes have been studied here on the basis of computation and accuracy. Accuracy is assured in the state linearization method, whereas the rate linearization method leads to a satisfactory trade-off between computational effort and accuracy. In the case of high-velocity motions, a combination of state and rate linearization is proposed.     

Necessary and sufficient conditions for quadratic linearization of a linearly controllable system

The existence of a canonical form for quadratic linearization of a linearly controllable system has been shown. However, if a linearly controllable system is amenable to quadratic linearization, it is not clear how to derive the transformation leading to quadratic linearization. Our approach to the derivation of necessary and sufficient conditions for quadratic linearization is constructive in nature in the sense that once the conditions are satisfied, the normalizing and input transformations are derived leading to quadratic linearization. We use state feedback to make the system eigenvalues non-resonant allowing the closed-form solution of the generalized homological equations which leads to the transformation solution. The proposed technique is illustrated with an example.     

Feedback linearizing control of vehicle longitudinal acceleration

The application of recently developed feedback linearization techniques to controlling the powertrain of an automobile is discussed. The objective of powertrain control is to regulate the output torque of the engine and transmission system to achieve a desired longitudinal acceleration of the vehicle. With higher model order and increasing system complexity, the design process for feedback linearization becomes harder and more tedious. However, the design process can be simplified for a class of nonlinear systems including the automobile powertrain. Simplification of the design process is accomplished by incorporating the single perturbation technique into the input-output linearization technique. Furthermore, the controller obtained by the simplified linearization technique is computationally simpler than the one obtained by the conventional linearization technique. Nonetheless, it provides good dynamic performance for the powertrain system