Attitude Control of Multiple Rigid Bodies with Uncertainties and Disturbances

Decentralized attitude synchronization and tracking control for multiple rigid bodies are investigated in this paper. In the presence of inertia uncertainties and environmental disturbances, we propose a class of decentralized adaptive sliding mode control laws. An adaptive control strategy is adopted to reject the uncertainties and disturbances. Using the Lyapunov approach and graph theory, it is shown that the control laws can guarantee a group of rigid bodies to track the desired time-varying attitude and angular velocity while maintaining attitude synchronization with other rigid bodies in the formation. Simulation examples are provided to illustrate the feasibility and advantage of the control algorithm.      

约束分段仿射系统的鲁棒最小时间控制

针对一类有界附加扰动的分段仿射系统,提出了一种离线低复杂性的鲁棒预测控制方法-鲁棒最小时间控制.首先计算系统的最大鲁棒正不变集和相关的局部稳定控制律,然后基于最大鲁棒正不变集通过多参数规划离线迭代计算系统的鲁棒一步集,得到的最小时间控制器覆盖最大鲁棒可稳定集.提出的鲁棒最小时间控制确保系统状态在最小时间内进入鲁棒正不变...     

四旋翼无人机鲁棒自适应姿态控制

 四旋翼无人机的姿态控制是自主飞行控制的核心,针对四旋翼姿态易受外界环境干扰和内部参数摄动等不确定性影响的问题,设计了一种鲁棒自适应反步控制器,以提高四旋翼的鲁棒性。建立了四旋翼完整的姿态运动模型,并将其转化为含有广义不确定性的多输入多输出非线性系统。根据该系统满足严格反馈的结构特点,设计了反步控制器; 针对系统中存在的外部干扰和内部参数摄动等不确定性,引入了一类鲁棒自适应函数来抵消该不确定性对系统的影响; 采用非线性跟踪微分器估计虚拟控制量的微分信号,减小了反步控制器设计中普遍存在的“计算膨胀”问题; 通过构造Lyapunov 函数证明闭环系统是稳定且指数收敛的。仿真结果表明,所设计控制器具有良好的控制效果和鲁棒性。     

考虑有执行器故障和有界扰动的鲁棒自适应容错补偿控制

考虑在执行器故障和外界干扰下, 用直接自适应状态反馈控制策略解决线性时不变连续时间系统的鲁棒容错补偿控制问题. 提出更一般且更实际的执行器故障模型. 在执行器故障和扰动的上界都未知下, 提出自适应律在线估计未知控制器参数. 然后基于自适应策略的信息, 构造一类鲁棒自适应状态反馈控制器自动补偿故障和扰动的影响. 基于李亚普诺夫定理, 在执行器故障和干扰下, 所得的自适应闭环系统可以被保证渐进稳定. 最后给出一个火箭整流罩模型的例子和它的仿真结果.     

一类中立时滞系统的一种改进的鲁棒自适应控制设计

The problem of adaptive robust control is addressed for a class of neutral delay systems. All uncertainties are assumed to be bounded by unknown constants. An improved adaptation law is proposed to estimate the square of these unknown bounds. Then, by making use of the updated values of the squared unknown bounds, an adaptive controller is designed to make the solution of the resultant closed-loop system uniformly ultimately bounded. Furthermore, this method avoids chattering and improves the performance. An example is given to illustrate the effectiveness of this method.     

一类不确定奇异摄动系统的鲁棒控制

本文研究了一类不确定奇异摄动系统，给出了亲折鲁棒控制器的设计方法，仿真结果表明，对这里研究的系统类型，本文所给控制具有更好的抗干扰能力。     

Practical Output Regulation of Uncertain Strict‐Feedback Form Systems

In this paper, an output feedback control is proposed to solve the practical output regulation problem of a class of nonlinear systems. In the first step of the design procedure, two sets of coordinate transformations are used to convert the output regulation problem of the system in the strict‐feedback form into the regulation problem of the transformed system in the uncertain normal form. Then, for the resulting system, a state feedback in the cast of nested sliding mode control is designed. Finally, by using the nonlinear separation principle, the output feedback controller is achieved by substituting the estimated states, resulting from the high‐gain observer, instead of real states. It can be shown that the states of the closed‐loop system are ultimately bounded. Copyright © 2011 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

具有鲁棒调节性能的H-鲁棒次优控制系统设计

本文研究的问题如下，对于具有构造型不确定性的被控对象，设计一动态反馈控制器，使得闭环系统满足Ｈ∞鲁棒次优性能要求。同时，对于满足给定微分方程的参考输入信号，具有鲁棒调节性能。研究结果表明，通过解一适当的Ｈ∞标准设计问题可以得到理想的控制器。基于黎卡提不等式的正定解，给出了控制器的具体设计方法。最后，还给出了该设计方法在二自由度机械手上应用的实验结果。     

运动目标姿态参数的一种CCD测量方法

结合计算机视觉技术和CCD测量原理。给出了一种运动目标姿态参数的测量方法,并推导了目标姿态测量的数学模型。对可能存在的误差源进行了分析,并提出了解决方法。该方法通过三个与CCD相匹配的标定点测量,采用四元法描述姿态,使得系统结构简单、速度快;仿真结果表明,系统角测量精度可达到1’,系统可以广泛应用于运动目标姿态的近距离测量。     

Continuous Robust Control for Series ElasticActuator With Unknown Payload Parametersand External Disturbances

In this paper, the torque tracking control problem for a class of series elastic actuators (SEAs) in the presence of unknown payload parameters and external disturbances is investigated. The uncertainties/disturbances rejection problem for SEAs is addressed from the view of a continuous nonlinear robust control development. Specifically, based on the analysis of a nonlinear SEA, the generic dynamics of SEA systems is described and a novel nonlinear control framework for SEAs is constructed. Then a RISE (robust integral of the sign of the error)-based second-order filter is introduced to synthesize the control law. Moreover, the control performance is theoretically ensured by Lyapunov analysis. Finally, some experimental results are included to demonstrate the superior performance of the proposed control method, in terms of transient response and robustness.      

Robust Adaptive Attitude Control for Non-rigid Spacecraft With Quantized Control Input

In this paper,an adaptive backstepping control scheme is proposed for attitude tracking of non-rigid spacecraft in the presence of input quantization,inertial uncertainty and external disturbance.TThe control signal for each actuator is quantized by sector-bounded quantizers,including the logarithmic quantizer and the hysteresis quantizer.By describing the impact of quantization in a new affine model and introducing a smooth function and a novel form of the control signal,the influence caused by input quantization and external disturbance is properly compensated for.Moreover,with the aid of the adaptive control technique,our approach can achieve attitude tracking without the explicit knowledge of inertial parameters.Unlike existing attitude control schemes for spacecraft,in this paper,the quantization parameters can be unknown,and the bounds of inertial parameters and disturbance are also not needed.In addition to proving the stability of the closed-loop system,the relationship between the control performance and design parameters is analyzed.Simulation results are presented to illustrate the effectiveness of the proposed scheme.     

持续有界扰动系统的嵌套不变椭圆集鲁棒控制

为了抑制外部持续有界扰动和模型不确定性对系统稳定性控制的影响,通过不变集理论,采用嵌套不变椭圆集鲁棒控制算法实现系统的快速稳定控制。控制算法分为离线算法和在线算法两部分。离线时根据公式得到一维状态变量序列,通过线性矩阵不等式方法优化得到嵌套不变椭圆集。在线时,根据系统状态变量在嵌套不变椭圆集的位置,构建新的不变椭圆集并计算得到系统的控制律。给出新的不变椭圆集满足系统控制要求的理论证明。通过与不变单椭圆集控制算法进行仿真比较,结果验证了上述算法的有效性,为持续有界扰动下模型不确定性系统的稳定控制,提供一种有效的控制方法。     

Robust Mrac Of A Nonautonomous Parabolic System With Spatiotemporally Varying Coefficients And Bounded Disturbance

In this paper, a robust model reference adaptive control of a parabolic system with unknown spatiotemporally varying coefficients and disturbance is investigated. In the adaptive control of time‐varying plants, the derivative of a Lyapunov function candidate, which allows the derivation of adaptation laws, is not negative semi‐definite in general. Under the assumption that the disturbance is uniformly bounded, the proposed robust adaptive scheme guarantees the boundedness of all signals in the closed loop system and the asymptotic convergence of the state error near to zero. With an additional persistence of excitation condition, the parameter estimation errors are shown to converge near to zero as well. Simulation results are provided.     

Suboptimal on Average Satellite Attitude Control in the Presence of Discrete Inaccurate Measurements

The problem of the active stabilization of the oscillations of an artificial satellite by thrusters is considered. The satellite moves in a circular orbit and oscillates around the center of mass in the plane of the orbit. Relay control is used to minimize fuel consumption. The state of the plant is not known with certainty, but it is refined by discrete inaccurate measurements. Therefore, the problem of the optimal on average control of a bundle of trajectories is investigated. The stability error is characterized by the average value of the energy integral. Taking into account the practical accuracy of executing the thruster firing and shutdown commands, the constrained minimization problem to be solved becomes discrete. The optimal control of one trajectory is used to control the bundle. This approach based on the principle of separation leads to the suboptimal control of the bundle, which, however, proves to be acceptable in practice.     

具结构不确定性的卫星姿态控制问题探讨

本文对弱阻尼特性的卫星姿态的鲁棒控制问题进行了研究。先采用加权办法将对象参数不确定性转化成未建模动态,然后用 H~∞方法进行设计,最后编制了 Safonov 鲁棒稳定裕度k_m 的软件,并对所设计控制系统的鲁棒性能进行了检验和分析。     

具有状态和控制约束的受扰离散线性切换系统的反馈控制

本文的主要贡献是针对一类具有重置函数及由外部不能控事件决定动态的离散时间线性切换系统,给出一些稳定性综合结论. 当系统受到外部有界扰动, 及状态和控制量约束时, 在输入到状态稳定性理论框架下, 研究使得系统镇定的线性状态反馈控制器设计方法. 针对这类混杂系统, 本文引入了受控D不变性的概念, 并给出检测某一混杂区域具有受控D不变性的充要条件. 进而, 提出一种能够使得受扰的线性切换系统镇定, 同时保证状态和控制量满足其约束的反馈矩阵的计算方法. 最后, 通过一个由两个子系统构成的数值例子来说明本文技术的应用性.     

有界扰动下约束非线性系统鲁棒经济模型预测控制EI北大核心CSCD

针对未知但有界扰动下约束非线性系统,提出一种新的鲁棒经济模型预测控制(Economic model predictive control,EMPC)策略,保证闭环系统对扰动输入具有输入到状态稳定性(Input-to-state stability,ISS).基于微分对策原理,分别优化经济目标函数和关于最优经济平衡点的鲁棒稳定性目标函数,其中经济最优性与鲁棒稳定性是具有冲突的两个控制目标.利用鲁棒稳定性目标最优值函数构造EMPC优化的隐式收缩约束,建立鲁棒EMPC的递推可行性和闭环系统关于最优经济平衡点相对于有界扰动输入到状态稳定性结果.最后以连续搅拌反应器为例,对比仿真验证本文策略的有效性.     

A New Robust Adaptive Neural Network Backstepping Control for Single Machine Infinite Power System With TCSC

For a single machine infinite power system with thyristor controlled series compensation (TCSC) device, which is affected by system model uncertainties, nonlinear time-delays and external unknown disturbances, we present a robust adaptive backstepping control scheme based on the radial basis function neural network (RBFNN). The RBFNN is introduced to approximate the complex nonlinear function involving uncertainties and external unknown disturbances, and meanwhile a new robust term is constructed to further estimate the system residual error, which removes the requirement of knowing the upper bound of the disturbances and uncertainty terms. The stability analysis of the power system is presented based on the Lyapunov function, which can guarantee the uniform ultimate boundedness (UUB) of all parameters and states of the whole closed-loop system. A comparison is made between the RBFNN-based robust adaptive control and the general backstepping control in the simulation part to verify the effectiveness of the proposed control scheme.      

虚拟环境中运动车辆行为仿真的程序方法研究

研究了具有自然起伏地形特征的虚拟环境中,运动车辆行为姿态变化的三维仿真问题。设计出一种根据车辆的支撑平面计算姿态显示参数,从而实现车体状态实时自动调节的算法。给出了算法的具体描述和实现结果,并对其中的关键技术进行了比较详细的讨论。该算法对车轮轮子个数没有限制,对于履带式车辆也是适用的。仿真显示了视觉上的逼真性,证明了该方法在虚拟仿真及虚拟现实其他领域的可应用价值。     

Adaptive Regulation Against Unknown Narrow Band Disturbances Applied to the Flying Height Control in Data Storage Systems

This paper presents an adaptive regulation approach in linear systems against exogenous narrow band inputs such as disturbances or reference signals consisting of a linear combination of biased sinusoids with unknown amplitudes, frequencies, and phases. The design of the regulator is based on considering a Q‐parameterized set of stabilizing controllers for the linear system, where an adaptive FIR filter with fixed IIR filtering is adopted as the Q parameter. The goal of the adaptation is to search within the set of stabilizing controllers for a controller, or equivalently a Q parameter, that yields regulation in the closed loop system. The proposed adaptive regulation algorithm is applied to an active suspension beam system, which is motivated by the flying height control problem in data storage systems. The experimental result of the closed loop system shows the effectiveness of the proposed adaptive regulator in achieving the desired tracking performance under unknown exogenous disturbances.