Formation Flight of Micro-Satellite Clusters

Richard M. Murray (PI)
Jerry Marsden
California Institute of Technology

Meir Pachter
Air Force Institute of Technology

Last updated: 03-Sep-2001

Overview Information Publications People

Project Overview

One of the significant challenges to successful formation flight of spacecraft is maintenance of the formation, i.e., control of the motion of the individual spacecraft to maintain the overall formation.  This includes both stabilization of a given formation and reconfiguring of the formation. While the dynamics and control a single spacecraft is well understood, a formation of spacecraft effectively acts a deformable body due to control forces which restore it to its desired formation. As a deformable body, the formation is capable of exhibit complex dynamic behavior. Effective control strategies must exploit this behavior as well as the natural dynamics of the system to achieve goals such as formation error minimization and minimal fuel consumption during formation reconfiguration. An additional concern is the impact a decentralized control structure would have control algorithm design and formation controllability.

Spacecraft dynamics are mechanical, meaning they admit a Lagrangian or Hamiltonian formulation. We are investigating the dynamics and control of formation flight by exploiting the mechanical structure of the dynamical system in conjunction with proven methods of linearization and structured uncertainty. At Caltech, we have developed analytical tools such as the energy-momentum method for assessing the stability of a mechanical system, as well as methodologies for control of mechanical systems. One important property of mechanical systems is the ability of small changes in the internal shape of the system to effect global motion of the system. Exploiting this phenomenon, termed geometric phase, in conjunction with the inherent nonlinear instability of a formation in certain regimes of its cluster of orbits, may yield methods for reconfiguring the formation which rely solely on internal motions of the formation, and hence are simple algorithmically and are amenable to a decentralized control architecture. Another relevant area of research at Caltech is in trajectory generation for mechanical systems. We are also developing approaches to solving optimal control problems for mechanical systems which exploit the mechanical structure and which are computationally tractable.

Project Information


J2 Dynamics and Formation Flight
W. S. Koon, J. E. Marsden, J. Masdemont and R. M. Murray
2001 AIAA Guidance, Navigation and Control Conference
Constrained Trajectory Generation for Microsatellite Formation Flying
Mark B. Milam, Nicolas Petit and Richard M. Murray
2001 AIAA Guidance, Navigation and Control Conference
Optimal Control of Affine Connection Control Systems: A Variational Approach
Alex Fax and Richard Murray
2000 Conference on Decision and Control
Finite-Horizon Optimal Control and Stabilization of Time-Scalable Systems
Alex Fax and Richard Murray
Submitted, 2000 Conference on Decision and Control
Optimal Control for Halo Orbit Missions
Serban, R., W. S. Koon, M. Lo, J. E. Marsden, L. R. Petzold, S. D. Ross and R. S. Wilson
IFAC Proceedings, March 16-18, 2000


The following individuals are supported under this project:


Richard M. Murray (