Model reference adaptive control with smooth switching scheme for piecewise linear systems and its application in turbofan engine control

A model reference adaptive control (MRAC) with smooth switching scheme was proposed for piecewise linear systems, and the method was utilized in turbofan engine control to avoid the discontinuity of control input. In this scheme, each sub-region of the operating envelope had its own MRAC controller, and smooth indicator function based smooth switching scheme was introduced to switch multiple controllers smoothly at the boundary of adjacent sub-regions. The Lyapunov stability analysis indicated that the proposed smooth switching scheme can guarantee the convergence of the closed-loop system during the controllers switching. The tracking error system was converted into a switched system to analyze the global stability of the closed-loop system. The advantage of the method was that the chattering of system output and instability caused by asynchronous switching can be eliminated. The simulation illustrates the effectiveness of the proposed control scheme in comparison with the existing MRAC controller with gain scheduling for turbofan engine.      

Nonlinear adaptive flight control system: Performance enhancement and validation

The problem of decreasing stability margins in L₁ adaptive control systems is discussed and an out-of-loop L₁ adaptive control scheme based on Lyapunov’s stability theorem is proposed. This scheme enhances the effectiveness of the adaptation, which ensures that the system has sufficient stability margins to achieve the desired performance under parametric uncertainty, additional delays, and actuator faults. The stability of the developed control system is demonstrated through a series of simulations. Compared with an existing control scheme, the constant adjustment of the stability margins by the proposed adaptive scheme allows their range to be extended by a factor of 4–5, bringing the stability margin close to that of variable gain PD control with adaptively scheduled gains. The engineered practicability of adaptive technology is verified. A series of flight tests verify the practicability of the designed adaptive technology. The results of these tests demonstrate the enhanced performance of the proposed control scheme with nonlinear parameter estimations under insufficient stability margins and validate its robustness in the event of actuator failures.     

Adaptive control for feedback-linearized missiles withuncertainties

A robust adaptive control scheme is proposed that can be applied to a practical autopilot design for feedback-linearized skid-to-turn (STT) missiles with aerodynamic uncertainties. The approach is to add a robust adaptive controller to a feedback-linearizing controller in order to reduce the influence of the aerodynamic uncertainties. The proposed robust adaptive control scheme is based on a sliding mode control technique with an adaptive law for estimating the unknown upper bounds of uncertain parameters. A feature of the proposed scheme is that missile systems with aerodynamic uncertainties can be controlled effectively over a wide operating range of flight conditions. It is shown, using Lyapunov stability theory, that the proposed scheme can give sufficient tracking capability and stability for a feedback-linearized STT missile with aerodynamic uncertainties. The six-degree-of-freedom nonlinear simulation results also show that good performance for several uncertainty models and engagement scenarios can be achieved by the proposed scheme in practical night conditions     

基于自适应滑模与模糊控制的导弹直接力/气动力复合控制系统优化设计

 针对导弹直接力/气动力复合控制问题,提出了一种基于自适应滑模控制(ASMC)与模糊逻辑的自动驾驶仪设计方法。该方法将整个导弹控制系统分为气动力控制子系统(ACS)和直接力控制子系统(RCS)两部分。前者采用自适应滑模控制理论进行设计,利用其所具有的强鲁棒性优点,克服了包括参数摄动与外界扰动在内的各类不确定性因素的影响。后者通过基于规则的模糊推理来确定不同条件下直接力作用的大小,以辅助提高气动力子系统的性能。在控制系统结构确定的条件下,利用遗传算法(GA)对各参数进行优化,实现了两个子系统之间的协调工作。仿真结果表明,所提出的控制方案对机动指令具有较好的跟踪效果,适用于直接力/气动力复合控制导弹的控制系统设计。     

基于自适应模糊系统的空天飞行器非线性预测控制

 针对一类多输入多输出非线性不确定系统,提出了基于自适应模糊系统的非线性预测控制方法。控制器由基于模糊系统的非线性预测控制器和鲁棒自适应控制器两个部分组成。根据系统的跟踪误差在线调整模糊系统的权值,使得模糊系统一致逼近被控对象中的非线性函数,通过泰勒展开设计出基于模糊系统的非线性预测控制律,避免了预测控制在线优化带来的繁重的计算负担。鲁棒自适应控制器则用于减少不确定和模糊逼近误差对系统的影响。所设计的控制器保证了闭环系统的最终一致有界稳定。基于Lyapunov稳定原理,给出了理论证明和分析。最后利用提出的控制方案设计了空天飞行器高超声速飞行姿态的控制系统,仿真结果表明了控制方案的有效性。     

基于瞬时无功功率理论和模糊PID控制的三相不平衡补偿算法

为满足三相不平衡飞机电网的无功功率实时补偿要求,设计了一种新型的静止无功补偿器（SVC）控制系统。该系统采用瞬时无功功率理论来精确检测基波正序和负序电压、电流,并推导出补偿导纳的表达式;SVC的整体控制采用了开环和闭环控制相结合的控制算法,并在闭环控制算法中,提出了自适应非线性模糊控制器在无功补偿控制系统中的应用方案。该方案结合了模糊控制和PID控制2种方法的优点,根据系统状况改变PID控制器的参数,以达到更好的动态控制效果。仿真研究结果表明,该新型SVC控制系统对于提高功率因数和补偿三相不平衡,具有响应快、精度高的控制效果。     

航空发动机自适应神经网络PID控制

本文提出了一种航空发动机多变量自适应神经网络 PID控制方法, 采用基于共轭梯度的神经网络学习算法在线整定控制器参数。该控制器的设计无需知道发动机精确模型, 具有响应速度快、抗干扰能力强和鲁棒性好等优点。控制器不仅算法简单, 实现容易, 而且适用范围广。      

基于径向基神经网络干扰观测器的空天飞行器自适应轨迹线性化控制

 研究了一种自适应轨迹线性化控制策略并应用于空天飞行器(ASV)飞行控制系统设计。通过理论分析指明当前轨迹线性化控制方法(TLC)对系统中的不确定存在鲁棒性不足的问题。为了解决这一问题,首先研究了一种径向基神经网络干扰观测器(RDO)技术,严格证明了RDO对于系统中不确定因素具有良好的逼近能力。然后利用RDO输出得到一种新的基于RDO的自适应TLC控制策略。神经网络自适应律采用Lyapunov方法设计,保证了闭环系统所有信号有界。最后采用新方案实现了ASV飞控系统,仿真结果表明整个闭环系统在鲁棒性能方面得到很大提高。     

非线性大系统直接自适应分散控制的神经网络逆系统方法

针对一类带有不确知关联的非线性大系统,提出了一种新型分散控制方案:以隔离子系统取代原子系统并求其逆系统,从而产生原子系统控制量的一部分;控制量的另一部分由用于补偿误差的在线神经网络形成。此方案的收敛性得到了论证,并在双倒立摆所形成的大系统中得到成功应用。     

非合作体附着下的组合体航天器自适应控制

空间中非合作体附着航天器本体后,新组合体惯量参数未知、系统引入的动量变化未知,容易造成航天器姿态控制失稳.针对此问题,提出了一种基于非合作组合体整体惯量估计的自适应控制方案,实现不同情形附着下新组合体姿态的快速和高精度恢复.通过构造李雅普诺夫函数,对自适应控制方案稳定性进行了证明.搭建的某卫星被非合作组合体附着后的姿控仿真平台表明,在非合作体惯量参数未知、引入动量未知以及附着前系统状态不定等恶劣情况下,采用该算法的组合体姿控误差可收敛到一个极小的领域内,可以实现对非合作组合体系统快速而有效的控制.     

一类非仿射型系统的神经网络自适应控制

针对一类未知控制方向的非仿射型系统的神经网络自适应控制问题进行了研究,提出了一种基于隐函数定理、反演设计技术、Nussbaum-型函数和神经网络理论相结合的新颖的自适应控制策略,成功地解决了该类系统控制器设计问题,为该类控制问题提出了一种解决思路。最后给出的数字仿真算例证明了该设计方法的有效性。     

基于相似理论的航空发动机转速自适应PID控制

根据航空发动机在相似坐标系中特性不变的特点，提出一种基于相似理论的航空发动机转速自适应PID控制。该方案采用衰减曲线法进行换算PID参数整定，获得自适应调节律。仿真结果表明控制器具有良好的动静态性能，自适应性和鲁俸性。所得参数变化规律对数控系统全包线内PID控制器的参数选择具有一定的指导意义。     

Attitude tracking control for variable structure near space vehicles based on switched nonlinear systems

An adaptive robust attitude tracking control law based on switched nonlinear systems is presented for a variable structure near space vehicle (VSNSV) in the presence of uncertainties and disturbances. The adaptive fuzzy systems are employed for approximating unknown functions in the flight dynamic model and their parameters are updated online. To improve the flight robust performance, robust controllers with adaptive gains are designed to compensate for the approximation errors and thus they have less design conservation. Moreover, a systematic procedure is developed for the synthesis of adaptive fuzzy dynamic surface control (DSC) approach. According to the common Lyapunov function theory, it is proved that all signals of the closed-loop system are uniformly ultimately bounded by the continuous controller. The simulation results demonstrate the effectiveness and robustness of the proposed control scheme.     

基于神经网络的MIMO非线性最小相位系统鲁棒自适应控制

 针对一类模型未知的具有不确定性和外部干扰的多输入多输出（MIMO）非线性最小相位系统提出了鲁棒自适应输出反馈跟踪控制方案。用高斯径向基函数（RBF）神经网络逼近对象未知非线性,用高增益观测器估计系统不可测量状态。所设计的鲁棒自适应控制器不仅能使闭环系统稳定,所有状态有界,而且跟踪误差一致最终有界,并保证最终边界足够小。仿真结果表明了所提出方法的有效性。     

Adaptive controller design for satellite attached by non-cooperative object

When non-cooperative body attachment occurs in space, the inertia of the new combination and the change of the system’s momentum are unknown. This uncertainty may lead to the instability of the spacecraft’s attitude control. In order to solve this problem, we propose an adaptive control scheme based on the inertia estimation of the new, combined system of non-cooperative body and satellite. This method can allow the new combination of different situations to reach a stable state with a high level of precision and speed. In this paper, the stability of the adaptive control scheme is proven by constructing a Lyapunov function. A simulation environment in which a non-cooperative body attaches to a satellite attaches to is constructed. The simulation shows that the attitude error converges to a small field when using the control scheme, regardless of unfavorable cases, including unknown inertia parameters, added momentum. In addition, the simulation results show the strong robustness of the control scheme for the new combination.     

参数不确定空间机械臂系统的增广自适应控制

讨论了载体位置与姿态均不受控制的漂浮基两杆空间机械臂系统的控制问题,为此对系统的运动学、动力学作了分析。结果表明 :结合系统动量守恒及动量矩守恒关系得到的系统广义Jacobi关系、以及系统的动力学方程将为系统惯性参数的非线性函数。证明了借助于增广变量法可以将增广广义Jacobi矩阵以及系统动力学方程表示为一组适当选择的惯性参数的线性函数。在此基础上,给出了系统参数未知时,空间机械臂末端抓手跟踪惯性空间期望轨迹的增广自适应控制方案。通过仿真运算,证实了方法的有效性。     

基于自适应Kalman滤波的导引头随动系统设计

主要研究导引头随动系统中探测器信号处理延迟的影响及其补偿控制算法。提出了一种自适应Kalman滤波延迟补偿方案,利用Kalman滤波的预测能力得到当前时刻视线角的估计值,进而得到此时的跟踪误差的估计值,取代被延迟的探测器输出进行闭环控制。考虑到导引头探测器的低更新频率、非等间隔量测等工程特点,又对上述滤波算法进行了一系列改进。仿真表明方法可以明显提高导引头在弹体扰动情况下的跟踪精度。     

卫星MEMS热控系统的动态特性及自主控制策略

在卫星热控系统中将高效冷却技术与系统层次的智能控制策略相结合是完成航天热控任务的理想候选方案。针对一种基于微机电系统(MEMS)的微槽道换热器和微百叶窗在卫星主动热控系统中应用的方案,应用集总参数法建立了受控对象的系统动态响应模型;提出了一种引入外热流协调因子和专家智能整定比例-积分-微分(PID)控制相结合的自主温度控制策略;完成了其在纳卫星上应用效果的仿真研究。仿真结果表明:自主温度控制策略能够根据当前的控制局势及变化趋势对多个被控量进行自主协调,不但能够有效满足星载电子设备的苛刻温控要求,同时也是实现卫星高度自主飞行的关键技术之一;该温度控制策略同样适用于其他控制场合。     

基于数据驱动的变循环发动机多变量自适应控制算法研究

本文针对变循环发动机包线范围大,自适应控制需求高的问题,在增广线性二次型调节器(ALQR)基础上,提出一种基于数据驱动的自适应ALQR(DA-ALQR)控制算法。构建了多变量系统自适应控制准则函数,以梯度下降法对控制器参数进行调整,借助基于数据驱动的动态线性化建模方法,递推进行输出对输入梯度的近似计算,实现了对ALQR控制参数的自适应调整。仿真结果表明,所设计的DA-ALQR控制器参数随发动机状态变化得到了有效调整,相较于ALQR控制算法,闭环系统动态性能得到了大幅度提升,推力在单外涵模式表现出较快的响应速度,在双外涵模式表现出更小的超调,转速同样表现出了超调减小和响应速度加快特性,验证了所提出方法的有效性。     

Further studies on efficient AFEC schemes for Ka-bandsatellite systems

Adaptive fade margin is required to counter the severe but varying rain attenuation in Ka satellite communications. In searching for a suitable rain countermeasure, the effectiveness of the adaptive forward error control (AFEC) scheme is studied. Two AFEC schemes using convolutional codes and concatenated codes are proposed and their performance analyzed. The schemes can provide a progressively adaptive fade margin of 10.1 and 10.4 dB, respectively, in excess of the systems fixed fade margin. To improve the efficient use of shared resources of the system, an AFEC scheme using double coding is introduced, and its performance is analyzed. In this scheme a single codec is used repeatedly, and as a result the hardware cost is reduced and the utilization increased. The effective usable capacity of a conceptual AFEC resource sharing scheme using Golay double coding is also analyzed