基于TS模糊区域模型的航天器姿态控制

由于燃料消耗和柔性部件展开等原因,挠性航天器的姿态动力学方程存在着参数的不确定性,因此,研究参数不确定TS模糊系统的鲁棒控制器设计方法,并将其应用到平面机动挠性航天器的姿态机动控制问题.将参数不确定TS模糊系统描述为TS模糊区域模型,根据PDC原理设计了模糊区域控制器,并用分段Lyapunov法证明了模糊控制系统的全局...     

挠性航天器的非线性PID和PI姿态控制器设计

针对存在模型不确性和常值干扰的挠性航天器, 提出一种不依赖于模型参数的非线性PID姿态控制器. 该控制器在小姿态偏差的情况下近似经典的线性PID控制器. 另外, 考虑到航天器上陀螺失效情况, 设计了一种仅需姿态测量信息的非线性PI控制器. 这两种控制器在局部均对常值干扰有抑制作用, 并能使无干扰作用的姿态控制系统半全局渐近稳定. 闭环系统的稳定性证明采用了奇异扰动理论, 以解决积分项的存在带来的稳定性分析问题. 文章最后用数学仿真验证了控制器的性能.     

Robust attitude tracking control of flexible spacecraft for achieving globally asymptotic stability

The three‐axis attitude tracking control problem in the presence of parameter uncertainties and external disturbances for a spacecraft with flexible appendages is investigated in this paper. Novel simple robust Lyapunov‐based controllers that require only the attitude and angular velocity measurement are proposed. The first controller is a discontinuous one composed of a nonlinear PD part plus a sign function, whereas the second one is continuous or even smooth by modifying the discontinuous part of the first one. For a general desired trajectory, both controllers can achieve globally asymptotic stability of the attitude and angular velocity tracking errors instead of ultimate boundedness. By using a two‐step proof technique, the partial stability of the proposed controllers for the resulting closed‐loop systems in the face of model uncertainties and unexpected disturbances is proven theoretically. To further enhance the control performance, a continuous controller is presented that utilizes the tracking errors for estimating the external disturbances. In addition, stability analysis is done. For all the developed controllers, numerical simulation results are provided to demonstrate their performance. Copyright © 2008 John Wiley & Sons, Ltd.     

转动惯量存在不确定性的挠性航天器滑模姿态控制

在转动惯量存在不确定性时,采用滑动模态控制方法对挠性航天器设计了姿态镇定控制律.由于挠性模态是不可量测的,首先设计了部分状态观测器对挠性模态进行估计.进而结合滑模控制方法,提出了基于观测器的滑模姿态控制律.采用Lyapunov方法证明了在存在转动惯量不确定性时,所设计的滑模姿态控制律能使闭环航天器姿态系统稳定.最后,通过数值仿真例子验证了所提出方法的有效性.     

Multilevel stabilization of large-scale systems: A spinning flexible spacecraft

Multilevel stabilization schemes for high order linear systems are proposed in the framework of the decomposition-aggregation method used so far for stability analysis of large-scale systems by vector Liapunov functions. In one scheme, the output feedback is applied and the control parameters are determined for low order subsystems to produce a stable aggregate model for the overall system. When system inputs are decentralized such that each subsystem has a distinct input, and states are available for control, another scheme is proposed which has a multilevel structure with local and global controllers. Both stabilization schemes are aimed at the maximization of structural parameters which couple the subsystems.An 11th-order linear model of a spinning flexible spacecraft is stabilized by the proposed decomposition-aggregation method using both the passive and the active stabilization devices. The method can take advantage of the special structural features of the model to provide the best estimate of the stability region for a salient parameter which couples the wobble and the spin motion of the spacecraft.     

Output attitude tracking for flexible spacecraft

In this work a class of nonlinear controllers has been derived for spacecraft with flexible appendages. The control aim is to track a given desired attitude. First, a static controller based on the measure of the whole state is determined. Then, a dynamic controller is designed; this controller does not use measures from the modal variables, and the variables measured are the parameters describing the attitude and the spacecraft angular velocity. Finally, it is shown that a relaxed version of the tracking problem can be solved when the only measured variable is the spacecraft angular velocity. Simulations show the performances of such control schemes.     

一类挠性航天器大角度快速机动的模型跟踪控制

研究一类构形为中心刚体带挠性梁的航天器的平面大角度快速机动控制问题.推导 了系统的非线性无穷维模型,设计了一种只利用中心刚体旋转角和角速度测量数据的模型跟 踪控制方案,基于无穷维空间的LaSalle不变原理,证明了相应闭环系统的渐近稳定性,并给 出了物理实验结果验证所设计的控制算法的有效性.     

Adaptive Dynamic Surface Control for Spacecraft Terminal Safe Approach with Input Saturation Based on Tracking Differentiator

This thesis studies the spacecraft terminal safe approach control problem considering input saturation. Based on the spacecraft relative motion model and sphere collision avoidance potential function, an anti-saturation controller and an adaptive finite-time anti-saturation controller using dynamic surface control(DSC) are presented for the situations of known and unknown upper bound of external disturbances respectively, which can guarantee that no collisions happen in the tracking process. The second-order tracking differentiator is introduced to design the controllers, which avoids the differential of the virtual control signal and ensures the tracking performance of system output signals. Meanwhile, the auxiliary system is introduced to handle input saturation. Lyapunov stability theory is adopted to prove that the states of system under the designed controllers are uniformly ultimately bounded and practical finite-time stable respectively, and the chaser spacecraft can approach to the desired position without collision. The numerical simulation results demonstrate that the chaser spacecraft using the designed controllers can realize terminal safe approach to target spacecraft, which further illustrate the effectiveness of the proposed controllers.     

On the coupled dynamics of small spacecraft and elastic deployable appendages

A thorough investigation of the dynamics of finite-mass satellites with a deployable elastic arm is presented. This work is focused on the interaction between spacecraft rigid body motion and its flexible arm dynamics during the deployment process. The classical Newton–Euler formulation and the Lagrangian approach are applied to the study of the dynamics of spacecraft and its deploying arm. Utilizing a non-Newtonian floating frame to define the arm elastic deformation field, the interactions between the spacecraft and its moving arm have been simulated. Complete equations of motion show that the spacecraft motion induces dynamical stiffness on the arm; in addition, axial and lateral motions of the deploying elastic arm change the spacecraft mass-characteristics and thus influence the spacecraft’s rigid body motions. The overall dynamic behavior is highly dependent on spacecraft mass characteristics in addition to the “arm deployment time (ADT)”. The results of case studies clearly indicate that some assumptions previously applied in appendage dynamic analysis are not conservative and produce erroneous results. This study realistically investigates the dynamics of elastic deploying appendages by considering finite-mass characteristics for small and massy spacecraft. The results reveal that for massive spacecraft the arm’s flexible dynamics is mainly excited through deployment, while for small spacecraft the energy transfers to the arm base and the spacecraft rigid body motion is considerably stimulated. Moreover, this work has further highlighted the effects of ADT in the overall system response. The findings of this work show that the energy distribution between arm’s elastic dynamics and spacecraft rigid body motions is an important factor in the design of any control system to limit unwanted arm-tip motions.     

Using the method of phase biplane to study dynamics of interactions of the elastic structural oscillations of the flexible spacecraft with the control system

A modal-physical representation of the mathematical model of flexible spacecraft enabling one to specify a diversity of the distinctions of the dynamics of controllable motion of the flexible objects was determined. The method of phase biplane enabling strict analysis of the dynamics of relay control of orientation of a flexible object with one dominating mode was described and extended to the method of the fuzzy phase biplane for approximate study of the dynamics of the multifrequency flexible spacecraft. Consideration was given to some important questions concerning the impact of structural flexibility on stability and performance of the control system of orientation of flexible spacecraft.     

Robust attitude and vibration control of a nonlinear flexible spacecraft

In this paper, the problem of attitude control of a three dimension nonlinear flexible spacecraft is investigated. Two nonlinear controllers are presented. The first controller is based on dynamic inversion, while the second approach is composed of dynamic inversion and µ‐synthesis schemes. It is assumed that only three torques in three directions on the hub are used. Actuator saturation is also considered in the design of controllers. To evaluate the performance of the proposed controllers, an extensive number of simulations on a nonlinear model of the spacecraft are performed. The performances of the proposed controllers are compared in terms of nominal performance, robustness to uncertainties, vibration suppression of panel, sensitivity to measurement noise, environmental disturbance and nonlinearity in large maneuvers. Simulation results confirm the ability of the proposed controller in tracking the attitude trajectory while suppressing the panel vibration. It is also verified that the perturbations, environment disturbances and measurement errors have only slight effects on the tracking and suppression performances. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

基于动态滑模控制的挠性航天器姿态控制

本文采用滑动模态控制方法对挠性航天器设计了姿态镇定控制律.首先,建立了挠性航天器的数学模型.其中,挠性航天器的运动学方程采用姿态四元数描述.然后,通过引入动态切换函数,设计挠性航天器的动态滑模姿态控制律.该控制律能对滑模姿态控制律中由符号函数项引起的抖振进行抑制.采用Lyapunov方法证明了所设计的动态滑模姿态控制律能使闭环航天器姿态系统稳定.最后,通过数值仿真例子验证了所提出方法的有效性.     

Synthesis of stabilizing spacecraft control based on generalized Ackermann’s formula

Problem of modal synthesis of controllers and observers using the generalized Ackermann’s formula is solved for a spacecraft as a complex dynamic system with high interconnections. All possible controller matrices (the whole set of controllers) are obtained for solution of the problem of stabilization of orbital orientation of the spacecraft in inseparable channels of bank and yaw angles.     

Heteroclinic bifurcations in attitude maneuver of coupled slosh-spacecraft with flexible appendage

In this paper, the chaotic dynamics in an attitude transition maneuver of a slosh-spacecraft coupled with flexible appendage in going from minor axis to major axis spin under the influence of dissipative effects due to fuel slosh and a small flexible appendage constrained to only torsional vibration is investigated. The slosh-spacecraft coupled with flexible appendage in attitude maneuver carrying a sloshing liquid is considered as multi-body system with the sloshing motion modeled as a spherical pendulum. ...     

考虑航天器舱体—附件耦合效应的热颤振准则

考虑具有端部附加质量的柔性附件及其和舱体的耦合效应,本文系统地推导出了一个带柔性附件的航天器热颤振准则,并用有限元程序进行了模拟校验.该准则揭示了柔性附件和舱体的质量特性和系统热诱发振动稳定性之间的关系.当舱体的质量特性远大于柔性附件的质量特性时,该准则就退化为悬臂柔性附件的热颤振准则.     

Attitude manoeuvre of spacecraft with long cantilever beam appendage by momentum wheel

Attitude manoeuvre of spacecraft with a long cantilever beam appendage by momentum wheel is studied. The dynamics equation of the main body is derived by conservation of angular momentum. The dynamics equation of the appendage is derived by force equilibrium principle. Two feedback control strategies of the momentum wheel are applied for the attitude manoeuvre of the main body. The lateral vibration of the appendage is suppressed by active control in proportion to its lateral displacement and velocity. The variation of residual nutation angle of the spacecraft or the residual transversal angular velocity of the main body in the manoeuvre process is researched with changes of steady state time of the manoeuvre, appendage parameters, control parameters on the appendage and appendage location. In addition, spacecraft response is researched when there are no active controls on the appendage.     

Global stabilisation of a class of generalised cascaded systems by homogeneous method

This paper considers the problem of global stabilisation of a class of generalised cascaded systems. By using the extended adding a power integrator technique, a global controller is first constructed for the driving subsystem. Then based on the homogeneous properties and polynomial assumption, it is shown that the stabilisation of the driving subsystem implies the stabilisation of the overall cascaded system. Meanwhile, by properly choosing some control parameters, the global finite-time stability of the closed-loop cascaded system is also established. The proposed control method has several new features. First, the nonlinear cascaded systems considered in the paper are more general than the conventional ones, since the powers in the nominal part of the driving subsystem are not required to be restricted to ratios of positive odd numbers. Second, the proposed method has some flexible parameters which provide the possibility for designing continuously differentiable controllers for cascaded systems, while the existing designed controllers for such kind of cascaded systems are only continuous. Third, the homogenous and polynomial conditions adopted for the driven subsystem are easier to verify when compared with the matching conditions that are widely used previously. Furthermore, the efficiency of the proposed control method is validated by its application to finite-time tracking control of non-holonomic wheeled mobile robot.     

挠性航天器姿态机动的变结构主动振动抑制

针对挠性航天器大角度姿态机动的振动抑制问题, 提出了一种双回路鲁棒主动振动控制方法. 首先, 对各低阶振动模态设计正位置反馈补偿器, 增加挠性模态的阻尼, 使其振动能够快速衰减; 然后, 基于变结构输出反馈控制理论, 给出控制器的设计方法. 最后, 将该方法应用于挠性航天器姿态机动控制, 仿真结果表明, 所提出的方法是可行而有效的.     

交会对接模拟系统姿态跟踪有限时间抗干扰控制

针对交会对接模拟系统的姿态同步问题,在存在扰动和系统不确定性的情况下,利用改进的快速非奇异终端滑模面和改进的自适应律设计两个有限时间抗干扰控制器.改进的自适应律保证了两个控制器的连续性和对干扰的鲁棒性,且第2个控制器能解决边界层理论存在的边界层内有限时间稳定性丢失的问题.李雅普诺夫理论推导和仿真结果表明,提出的两个控制器能保证系统的有限时间稳定性,系统能快速收敛到平衡点.     

Output feedback control for attitude tracking

In this paper the problem of attitude tracking control for a rigid spacecraft is addressed. It is assumed that only attitude measurements are available, and thus spacecraft's angular velocity has to be properly estimated. Two alternative schemes are proposed in which the unit quaternion is adopted to represent the orientation. In the first scheme, a second-order model-based observer is adopted to estimate the angular velocity used in the control law. In the second scheme, an estimate of the angular velocity error is obtained through a lead filter. Sufficient conditions ensuring local exponential stability of the two controllers are derived via Lyapunov analysis.