Coupled Dynamics and Integrated Control for Position and Attitude Motions of Spacecraft:A Survey

Inspired by the integrated guidance and control design for endo-atmospheric aircraft,the integrated position and attitude control of spacecraft has attracted increasing attention and gradually induced a wide variety of study results in last over two decades,fully incorporating control requirements and actuator characteristics of space missions.This paper presents a novel and comprehensive survey to the coupled position and attitude motions of spacecraft from the perspective of dynamics and control.To this end,a systematic analysis is firstly conducted in details to show the position and attitude mutual couplings of spacecraft.Particularly,in terms of the time discrepancy between spacecraft position and attitude motions,space missions can be categorized into two types:space proximity operation and space orbital maneuver.Based on this classification,the studies on the coupled dynamic modeling and the integrated control design for position and attitude motions of spacecraft are sequentially summarized and analyzed.On the one hand,various coupled position and dynamic formulations of spacecraft based on various mathematical tools are reviewed and compared from five aspects,including mission applicability,modeling simplicity,physical clearance,information matching and expansibility.On the other hand,the development of the integrated position and attitude control of spacecraft is analyzed for two space missions,and especially,five distinctive development trends are captured for space operation missions.Finally,insightful prospects on future development of the integrated position and attitude control technology of spacecraft are proposed,pointing out current primary technical issues and possible feasible solutions.

Classification of solar sail attitude dynamics with and without angular momentum

This paper describes attitude dynamics properties of spinning,momentum-biased and zero-momentum solar sail spacecraft.The model called“Generalized Sail Dynamics Model”(GSDM)is introduced,which can deal with general and practical sail configurations,such as arbitrary optical property distribution,shape and surface wrinkles.Attitude stability criteria and other key dynamical characteristics are derived and compared by compact analytical equations induced from the GSDM.The newly derived zero-momentum sail dynamics is compared with that of spinning and momentum-biased sails.It is shown that the spinning and momentum sails have an advantage in terms of dynamical stability whereas zero-momentum sails are only statically stable.With this special property,angular momentum-stabilized sails can realize a sun-pointing stable attitude with almost zero-fuel,which are discussed with actual space flight experience of the JAXA’s two interplanetary missions,IKAROS and Hayabusa2.

Chaotic attitude and reorientation maneuver for completely liquid-filled spacecraft with flexible appendage

The present paper investigates the chaotic attitude dynamics and reorientation maneuver for completely viscous liquid-filled spacecraft with flexible appendage. All of the equations of motion are derived by using Lagrangian mechanics and then transformed into a form consisting of an unperturbed part plus perturbed terms so that the system＇s nonlinear characteristics can be exploited in phase space. Emphases are laid on the chaotic attitude dynamics produced from certain sets of physical parameter values of the spacecraft when energy dissipation acts to derive the body from minor to major axis spin. Numerical solutions of these equations show that the attitude dynamics of liquid-filled flexible spacecraft possesses characteristics common to random, non- periodic solutions and chaos, and it is demonstrated that the desired reorientation maneuver is guaranteed by using a pair of thruster impulses. The control strategy for reorientation maneuver is designed and the numerical simulation results are presented for both the uncontrolled and controlled spins transition.

CHAOTIC ATTITUDE MOTION OF A MAGNETIC RIGID SPACECRAFT

Chaotic attitude motion of a magnetic rigid spacecraft in a circular orbit of the earth is treated. The dynamical model of the problem was derived from the law of moment of momentum. The Melnikov analysis was carried out to prove the existence of a complicated nonwandering Cantor set. The dynamical behaviors were numerically investigated by means of time history, Poincar map, power spectrum and Liapunov exponents. Numerical simulations indicate that the onset of chaos is characterized by break of torus as the increase of the torque of the magnetic forces.

New-type of flying control for spinning TVC vehicle

A new kind of problem for TVC vehicle spinning in the boost stage had been researched. The study of non-linear flying dynamics modeling and dynamic properties of TVC vehicles reveal dominant coupled factors that affect the attitude stability and attitude precision of the pitch channel and yaw channel. The paper emphasizes the inertial delay coupled effects between vehicle＇s pitch servo system and yaw servo system, which have always been neglected. An uncoupled plan and control algorithm are put forward from the standpoint of engineering implementation to provide theoretical guidance and reference for further research on this complicated flying control.

Flatness-Based Control in Successive Loops for Unmanned Aerial Vehicles and Micro-Satellites

The control problem for the multivariable and nonlinear dynamics of unmanned aerial vehicles and micro-satellites is solved with the use of a flatness-based control approach which is implemented in successive loops.The state-space model of(i)unmanned aerial vehicles and(ii)micro-satellites is separated into two subsystems,which are connected between them in cascading loops.Each one of these subsystems can be viewed independently as a differentially flat system and control about it can be performed with inversion of its dynamics as in the case of input–output linearized flat systems.The state variables of the second subsystem become virtual control inputs for the first subsystem.In turn,exogenous control inputs are applied to the first subsystem.The whole control method is implemented in two successive loops and its global stability properties are also proven through Lyapunov stability analysis.The validity of the control method is confirmed in two case studies:(a)control and trajectories tracking for the autonomous octocopter,(ii)control of the attitude dynamics of micro-satellites.

Observer-based control for the platform of a tethered space robot

This paper addresses the attitude control problem of a space tethered robot platform in the presence of unknown external disturbance caused by a connecting elastic tether. The tethergenerated unknown disturbance leads to tremendous challenges for attitude control of the platform.In this work, the perturbed attitude dynamics of the platform are derived with a consideration of the libration of the elastic tether, and then with the purpose of compensating the unknown disturbance, major attention is dedicated to develop a nonlinear disturbance observer based on gyros measurements, after which, an adaptive attitude scheme is proposed by combining the disturbance observer with a sliding mode controller. Finally, benefits from the observer based on an adaptive controller are validated by series of numerical simulations.

Minimum-torque Earth Off-nadir Pointing Control of Gravity-gradient Stabilized Small Satellites

Earth off\|nadir pointing technology can be used on a small satellite to provide larger nadir earth surface imaging coverage. In this paper, the satellite attitude dynamics equations including the gravity\|gradient torque and wheel motor torque are derived using Euler parameters. The necessary conditions for optimum solutions subject to the performance index are obtained via Pontryagin's principle. The resulting two\|point boundary value problem is solved numerically with an optimal slew illustrated by example.

Spacecraft Dynamic Characteristics While Deploying Flexible Beams

The attitude dynamic equations of a spacecraft while deploying two flexible beams and the beam equations were developed from momentum theory. The dynamic equations were solved numerically using the Runge-Kutta method to calculate the vibration amplitudes of the flexible beams and the attitude angular velocity. The results show that the vibration amplitudes increase as the beam length increases or as the initial attitude angular velocity increases. The results also show that the vibration amplitudes decrease as the deployment velocity increases.

Super twisting controller for on-orbit servicing to non-cooperative target

A relative position and attitude coupled controller is proposed for rendezvous and docking between two docking ports located in different spacecraft. It is concerned with servicing to a tumbling non-cooperative target spacecraft in arbitrary orbit subjected to external disturbances.By considering both kinematic and dynamical coupled effects of relative rotation on relative translation, a coupled dynamic model is established to represent the relative motion of docking port on target spacecraft with respect to another on the service spacecraft. The spacecraft control is based on the second order sliding mode algorithm of super twisting（ST）. It is schemed to manipulate the relative position and attitude synchronously. A formal proof of the finite time convergence property of the closed-loop system is derived theoretically by the second method of Lyapunov. Numerical simulations with the designed ST controller are presented to validate the analytic analysis by contrast with the twisting control algorithm. Simulation results demonstrate that the proposed relative position and attitude integrated controller is characterized by high precision, strong robustness and high reliability.