EXACT NULL CONTROLLABILITY OF NON-AUTONOMOUS FUNCTIONAL EVOLUTION SYSTEMS WITH NONLOCAL CONDITIONS

In this article, by using theory of linear evolution system and Schauder fixed point theorem, we establish a sufficient result of exact null controllability for a non-autonomous functional evolution system with nonlocal conditions. In particular, the compactness condition or Lipschitz condition for the function g in the nonlocal conditions appearing in various literatures is not required here. An example is also provided to show an application of the obtained result.

Minimal Time of Null Controllability for the 1D Heat Equation by a Strategic Zone Profile

The aim of this work is to improve the minimum time of null controllability of the 1D heat equation by using the notion of strategic zone actuators. In fact, motivated by the work of Khodja on the null controllability of the heat equation and of El Jai on the controllability by the use of strategic zone actuators, we managed, in this work, to improve the minimal time of null controllability to the 1D heat equation. However, the restrictions and difficulties to establish the inequality of coercivity of the parabolic operator, require to seek other methods of internal control. Thus in this paper, a mixed method combining the method of moments and the notion of strategic profile was used to find a better minimal time of null controllability of the 1D heat equation.

Exact controllability of rational expectations model with multiplicative noise and input delay

This paper considers the rational expectations model with multiplicative noise and input delay,where the system dynamics rely on the conditional expectations of future states.The main contribution is to obtain a sufficient condition for the exact controllability of the rational expectations model.In particular,we derive a sufficient Gramian matrix condition and a rank condition for the delay-free case.The key is the solvability of the backward stochastic difference equations with input delay which is derived from the forward and backward stochastic system.

Bang-Bang Principle of Time Optimal Controls and Null Controllability of Fractional Order Parabolic Equations

In this paper, we establish a bang-bang principle of time optimal controls for a controlled parabolic equation of fractional order evolved in a bounded domain Ω of R^n, with a controller w to be any given nonempty open subset of Ω. The problem is reduced to a new controllability property for this equation, i.e. the null controllability of the system at any given time T 〉 0 when the control is restricted to be active in ω× E, where E is any given subset of [0, T] with positive （Legesgue） measure. The desired controllability result is established by means of a sharp observability estimate on the eigenfunctions of the Dirichlet Laplacian due to Lebeau and Robbiano, and a delicate result in the measure theory due to Lions.

On null Controllability of fractional stochastic differential system with fractional Brownian motion

In this paper,we are dealing with the null controllability of fractional stochastic differential system with fractional Brownian motion.The null controllability for Sobolev-type Hilfer fractional stochastic differential system with fractional Brownian motion of Clarke’s subdifferential type is studied.The sufficient conditions for null controllability of fractional stochastic differential system with fractional Brownian motion and control on the boundary are established.Finally,an example is given to illustrate the obtained results.

Null Controllability of Some Reaction-Diffusion Systems with Only One Control Force in Moving Domains

In this article, the authors establish the local null controllability property for semilinear parabolic systems in a domain whose boundary moves in time by a single control force acting on a prescribed subdomain. The proof is based on Kakutani＇s fixed point theorem combined with observability estimates for the associated lineaxized system.

One-Sided Exact Boundary Null Controllability of Entropy Solutions to a Class of Hyperbolic Systems of Conservation Laws with Characteristics with Constant Multiplicity

This paper proves the local exact one-sided boundary null controllability of entropy solutions to a class of hyperbolic systems of conservation laws with characteristics with constant multiplicity. This generalizes the results in [Li, T. and Yu, L., One-sided exact boundary null controllability of entropy solutions to a class of hyperbolic systems of conservation laws, To appear in Journal de Mathematiques Pures et Appliquees, 2016.] for a class of strictly hyperbolic systems of conservation laws.

Null controllability for a fourth order parabolic equation

In the paper, the null interior controllability for a fourth order parabolic equation is obtained. The method is based on Lebeau-Rabbiano inequality which is a quantitative unique continuation property for the sum of eigenfunctions of the Laplacian.

Null Controllability for Some Systems of Two Backward Stochastic Heat Equations with One Control Force

Abstract The authors establish the null controllability for some systems coupled by two backward stochastic heat equations. The desired controllability result is obtained by means of proving a suitable observability estimate for the dual system of the controlled system.

Balance recovery control for biped robot based on reaction null space method

A biped walking robot should be able to keep balance even in the presence of disturbing forces. This paper presents a step strategy concept of biped walking robot that is stabilized by using reaction null space method. The called ＂step strategy＂ can be modeled by means of the reaction null space method that introduced earlier to tackle dynamic interaction problems of free-floating robots, or moving base robots in general. 6-DOF biped robot model simulations are used to confirm the validity.

基于零空间的船舶自主靠泊自抗扰控制分配

[目的]针对船舶自主靠泊过程中遇到的环境载荷、岸壁效应、模型不确定以及控制分配误差等多源干扰的影响,提出一种基于零空间的自抗扰控制(ADRC)分配方法。[方法]首先,建立船舶靠泊运动数学模型、多源干扰模型和控制分配模型,并据此设计神经网络扩张状态观测器(NNESO)实时估计船舶运动及其所受到的多源干扰;然后,引入零空间技术设计控制分配算法,并基于该方法实现先泊位外镇定再平行靠泊方案;最后,证明船舶自主靠泊系统在所提方法下所有误差信号一致最终有界,保证船舶自主靠泊过程的安全性。[结果]仿真对比结果表明,所提方法在轨迹跟踪效果与二次规划(QP)法近似的情况下,求解所需时间为其1.3%,艏向最大分配误差为伪逆法(PI)的36.51%。[结论]所提方法在满足靠泊运动控制精度的同时,求解所需时间明显缩短,最大分配误差显著降低,保证了控制分配的实时性与精确性。

改进哈里斯鹰算法用于阵列天线方向图赋形

由于目前群智能优化算法在解决直线阵列天线方向图的旁瓣电平抑制和零陷控制问题时容易陷入局部最优以及收敛速度较慢的问题,提出了一种改进哈里斯鹰优化算法。该算法首先引入单鹰探索策略来扩大算法的全局搜索范围,然后引入自适应控制理论,用以提高算法的搜索精度并加快算法的收敛。仿真结果表明,与粒子群算法、布谷鸟搜索算法、蚁群优化算法以及标准哈里斯鹰优化算法相比,所提算法在压低直线形阵列天线方向图的旁瓣电平和控制零陷方面更具优越性。

基于零空间行为融合的多智能体编队控制综述

针对单智能体在民用和军用领域无法完成现实场景下复杂任务的问题,本文综述了零空间行为融合算法。阐述零空间行为融合算法的设计思想与数学模型,介绍零空间行为融合算法的文献计量分析。综述了零空间算法的研究进展,包括编队速度饱和、行为转换不连续、行为优先级分配和多种算法结合方面的改进工作,并分析当前研究存在的问题。研究表明:零空间行为融合算法在多智能体编队控制领域,提高算法的自适应性、考虑动力学特性、异构编队和行为函数优化是该算法未来的发展方向。

全空间中带位势热方程的采样时间最优控制

该文考虑全空间中带常值位势的热方程的采样时间最优控制问题,给出了一定条件下时间最优控制的存在性和最小范数时间最优控制满足的Pontryagin最大值原理.为得到时间最优控制的存在性,该文建立了新的能观不等式,通过该不等式得到控制系统的采样渐近零能控,并结合Fenchel对偶理论对实现渐近零能控的控制的最小代价进行了刻画.

过驱动卫星姿态动态控制分配研究

针对受干扰、飞轮故障、安装偏差和饱和影响的过驱动卫星的姿态控制问题提出了一种控制器设计方法。首先建立了过驱动卫星的姿态方程,给出了飞轮安装偏差、故障和饱和的数学描述。随后设计了存在外界不确定干扰和飞轮安装偏差时的滑模控制律,再应用动态控制分配解决过驱动卫星飞轮故障问题,最后考虑飞轮存在饱和时,使用零空间法使飞轮力矩指令保持在可行区间之内。设计的控制方法避免了复杂的控制器设计过程,控制器更为简单,适应性更广,更容易理解且更易于工程应用。

一种辐射零点可控的紧凑型滤波贴片天线

提出了一种辐射零点可控的紧凑型滤波贴片天线。该滤波天线以基本的微带贴片天线为原型,主要由一个简单的金属辐射贴片和两个对称的分割形槽组成。两个分割形槽蚀刻在金属贴片上,使得高/低频段分别产生两个宽边辐射零点,从而引入滤波选频功能。该结构未引入额外滤波电路和其他寄生单元,节省了空间尺寸,结构更加紧凑;两个辐射零点独立可控,提高了设计的灵活度。且在实现滤波选频功能的同时,对天线增益的影响很小。利用HFSS仿真软件优化滤波天线结构,制作了一个实物模型并进行了测试。测试结果与仿真结果基本一致。测试结果表明,提出的滤波天线工作在2.40 GHz,两个独立可控的辐射零点分别位于1.96 GHz和2.66 GHz,平均实际增益约为7.0 dBi,带外抑制水平超过39 dB。

基于零空间方法的四旋翼无人机避障与协同编队控制

针对四旋翼无人机在编队飞行执行任务时可能遭遇障碍物问题,考虑多无人机避障及机间避撞的需求,提出1种基于零空间方法的四旋翼无人机避障与协同编队控制算法。首先,建立四旋翼无人机动力学模型,并建立虚拟控制量简化控制模型;其次,基于零空间方法进行避障与协同编队控制算法研究,将无人机任务执行分解为目标趋向任务、避障避撞任务和协同编队任务,并根据优先级进行任务融合得到期望速度;再次,基于PID方法设计控制律;最后,通过仿真验证所提控制算法的有效性。所提方法可保证四旋翼无人机在编队飞行中遭遇障碍物时的飞行安全。

空间站宏微机械臂动力学建模与零反作用控制

为满足空间站宏微机械臂级联在一起运动的任务需求,文章提出一种简化的动力学建模方法。首先利用雅克比矩阵将柔性关节宏机械臂等效为柔性基座,根据柔性基座、刚性微机械臂以及两者之间的耦合作用推导出柔性基座机械臂动力学模型。基于机械臂系统的动力学冗余特性,采用零反作用运动控制法使柔性基座与微机械臂之间运动解耦。文中数学模型的仿真结果与商业软件一致,表明了柔性基座机械臂模型的正确性。另外,将零反作用轨迹跟踪控制法成功应用于该模型,使得微机械臂末端在跟踪期望轨迹的同时完全不会激起基座的弹性变形。

欠驱动无人艇集群协同编队路径规划仿真

针对欠驱动无人艇集群协同编队路径规划问题,在零空间行为法的基础上引入虚拟结构法,解决了零空间行为法存在的编队稳定性不足的问题。通过将欠驱动无人艇集群编队任务分解成三个优先级不同的子任务,分别求解每个子任务的任务输出函数,最后将所有子任务的任务输出函数进行综合,得到综合的任务输出函数。在MATLAB环境与基于QT Creat环境的无人艇仿真控制平台进行了仿真验证,仿真结果证明,上述算法的有效性与可行性,欠驱动无人艇集群能够达到编队路径规划目的。

吸气式高超声速飞行器考虑控制约束的设计优化

为了能够获得性能卓越,可靠的吸气式高超声速飞行器(AHSV)设计,需要考虑其特殊动力学特性及控制系统的性能约束,研究面向控制系统设计的系统设计优化策略.首先,简要介绍了AHSV第1原理建模与参数化建模相关的问题与方法;其次,分析了AHSV系统模型与控制系统性能之间的约束耦合特性:系统模型的不稳定极点及其左特征向量与控制信号的饱和约束确定了反馈控制系统的零可控区域;系统模型右半平面(RHP)零极点对于反馈闭环系统灵敏度函数与补灵敏度函数具有峰值约束与带宽限制;最后,考虑系统模型与控制系统约束耦合的特性,根据选取的总体优化设计目标,介绍了系统本体与控制系统组合优化的相关策略.并简要分析了各优化策略的实用性及适用范围.对于AHSV考虑控制系统性能约束的优化设计提供了一种研究方法和设计思路.