Adaptive output feedback tracking control of multiple spacecraft (original) (raw)

Nonlinear dynamics and output feedback control of multiple spacecraft in elliptical orbits

Proceedings of the 2000 American Control Conference. ACC (IEEE Cat. No.00CH36334), 2000

This paper considers the problem of relative position control for multiple spacecraft formation flying. Specifically, the nonlinear dynamics describing the motion of a follower spacecraft relative to a leader spacecraft are developed for the case where the leader spacecraft is in an elliptical orbit. Next, a Lyapunov-based, nonlinear, output feedback control law is designed which guarantees global uniform ultimate boundedness of the position and velocity tracking errors in the presence of unknown, spacecraft masses and disturbance force parameters. Simulation results are provided to illustrate the performance of the output feedback control design methodology for formation maintenance in ideal, naturally attractive, orbits.

Output feedback control of relative translation in a leader-follower spacecraft formation

2006

We present a solution to the problem of tracking relative translation in a leader-follower spacecraft formation using feedback from relative position only. Three controller configurations are presented which enables the follower spacecraft to track a desired reference trajectory relative to the leader. The controller design is performed for different levels of knowledge about the leader spacecraft and its orbit. The first controller assumes perfect knowledge of the leader and its orbital parameters, and renders the equilibrium points of the closed-loop system uniformly globally asymptotically stable (UGAS). The second controller uses the framework of the first to render the closed-loop system uniformly globally practically asymptotically stable (UGPAS), with knowledge of bounds on some orbital parameters, only. That is, the state errors in the closed-loop system are proved to converge from any initial conditions to a ball in close vicinity of the origin in a stable way, and this ball can be diminished arbitrarily by increasing the gains in the control law. The third controller, based on the design of the second, utilizes adaptation to estimate the bounds that were previously assumed to be known. The resulting closed-loop system is proved to be uniformly semiglobally practically asymptotically stable (US-PAS). The last two controllers assume boundedness only of orbital perturbations and the leader control force. Simulation results of a leader-follower spacecraft formation using the proposed controllers are presented.

Spacecraft formation flying: a review and new results on state feedback control

Acta Astronautica, 2009

This paper presents a review of previous work within the field of spacecraft formation flying, including modeling approaches and controller design. In addition, five new approaches for tracking control of relative translational motion between two spacecraft in a leader-follower formation are derived. One PD controller with feedback linearisation is derived and shown to result in an exponentially stable equilibrium point of the closed loop system. Four nonlinear controllers are derived and proved by using Lyapunov theory and Matrosov's theorem to leave the closed loop system uniformly globally asymptotically stable. Results from the simulation of the system with the derived controllers are presented, and compared with respect to power consumption and tracking performance.

Output Attitude Tracking of a Formation of Spacecraft

Proceedings of the 17th IFAC World Congress, 2008, 2008

In this paper we will consider the control of spacecraft in a leader-follower formation using attitude measurements only. To analyze the formation under nonvanishing disturbances, we make use of the concept of uniform semiglobal practical exponential stability. To ease the Lyapunov analysis a new theorem is provided, giving sufficient conditions for systems presenting a cascaded structure to satisfy this definition. Finally, output control is applied to both the leader and follower spacecraft and the stability of the overall system is analyzed by applying this new result.

Asymptotic Tracking Control for Spacecraft Formation Flying with Decentralized Collision Avoidance

This paper presents a tracking control scheme for spacecraft formation flying with a decentralized collisionavoidance scheme, using a virtual leader state trajectory. The configuration space for a spacecraft is the Lie group SE3, which is the set of positions and orientations in three-dimensional Euclidean space. A virtual leader trajectory, in the form of attitude and orbital motion of a virtual satellite, is generated offline. Each spacecraft tracks a desired relative configuration with respect to the virtual leader in an autonomous manner, to achieve the desired formation. The relative configuration between a spacecraft and the virtual leader is described in terms of exponential coordinates on SE3. A continuous-time feedback tracking control scheme is designed using these exponential coordinates and the relative velocities. A Lyapunov analysis guarantees that the spacecraft asymptotically converge to their desired state trajectories. This tracking control scheme is combined with a decentralized collision-avoidance control scheme generated from artificial potentials for each spacecraft, which includes information of relative positions of other spacecraft within communications range. Asymptotic convergence to the desired trajectory with this combined control law is demonstrated using a Lyapunov analysis. Numerical simulation results verify the successful application of this tracking control scheme to a formation maneuver with decentralized collision avoidance.

Adaptive Control Methods in Satellite Formation Flying

2017

In order to face numerous challenges in the autonomous control of relative position in space, this work proposes an introduction and critical comparison of three different approaches to adaptive control. Uncertainties coming from unknown orbital perturbations and system errors, together with the need of a high precision control, i.e. during docking maneuvers, make adaptive algorithms particularly attractive. Adaptive control allows real-time estimation of unknown parameters such as drag coefficient, thrust misalignment and magnitude error, spacecraft mass variation, and their inclusion in the control law. Apart from parameters estimation, this paper describes three ways of dealing with system nonlinearities: backstepping algorithm, sliding mode technique and the use of a fuzzy method. A final comparison between the three control techniques is provided, including comments regarding the respective applicability on actual space missions.

Adaptive control for satellite formation flying under thrust misalignment

Acta Astronautica, 2009

Satellite formation flying requires precise control of relative positioning under external disturbances and parameter uncertainties. Since thrust magnitude error and misalignment are not negligible in the electric propulsion system, they should be considered in satellite formation flying to meet mission requirements. In this paper, an adaptive control approach combined with backstepping technique is developed by using Lyapunov control design approach for the relative position tracking problem of satellite formation flying in the presence of thrust misalignment uncertainty and disturbances. The proposed controller guarantees global asymptotic convergence for position and velocity tracking error to ensure desired performance during the satellite formation flying mission.

Adaptive Learning Control For Spacecraft Formation Flying

Advances in Dynamics and Control, 2004

This chapter considers the problem of spacecraft formation flying in the presence of periodic disturbances. In particular, the nonlinear position dynamics of a follower spacecraft relative to a leader spacecraft are utilized to develop a learning controller that accounts for the periodic disturbances entering the system model. Using a Lyapunov-based approach, a full-state feedback control law, a parameter update algorithm, and a disturbance estimate rule are designed that facilitate the tracking of given reference trajectories in the presence of unknown spacecraft masses. Illustrative simulations are included to demonstrate the efficacy of the proposed controller.

Output control of spacecraft in leader follower formation

2008

In this paper we will consider the control of spacecraft in a leader-follower formation using position measurements only. To analyze the formation under non vanishing disturbances, new definitions of practical exponential stability are given together with sufficient conditions for systems to satisfy these properties.

Linearizing Assumptions and Control Design for Spacecraft Formation Flying Maneuvers

2004

In this paper the validity of neglecting the relative effect of the gravitational force of the Earth on a formation of spacecraft is studied. This relative effect is treated as an unknown disturbance acting on the system and all control laws are designed using a linear model that neglects this effect. A previously designed simple linear feedback controller is tested under different conditions using the linear model and the full nonlinear model that includes the gravitational force. All tests are carried out in the presence of saturation limits. The results show that the linear controller exhibits oscillations in the transient response and poor robustness under certain conditions. It also exhibits a high saturation tendency, thereby leading to increased fuel consumption. This controller also causes a high rise in the velocity errors at ordinary values of the gains. Based on the behavior of this controller, new controllers are proposed that overcome these drawbacks without any need fo...