A Relayed Formation Flying Control with Analogy Discussion to Traffic System
- Paper number
IAC-06-C1.8.02
- Author
Dr. Junichiro Kawaguchi, Japan Aerospace Exploration Agency (JAXA)/ISAS, Japan
- Coauthor
Mr. Hiroya Mizuta, University of Tokyo, Japan
- Year
2006
- Abstract
The formation flying control on orbit, especially in the constellation, is usually implicitly assumed to maintain the relative position to each other by measuring the distance between the neighbors. However, theoretically, against the expectation, this control scheme easily fails and the distance motion shows divergent resonant behavior. This phenomenon is analogous to that appears in the traffic control on the ground. The essence lies in the fact that local stability does not guarantee the entire stability in such decentralized control. This paper presents the strategy, by which this resonant motion is suppressed and maintained automatically. The method proposed here does not assume and does not necessarily rely on the measurement of the mutual distance but on the relayed information structure making the acceleration command flow to the neighbors. The system comprises two layers, upper part of which leaves the distance control to each spacecraft (driver) responsibility, while the stabilizing input is accumulated and relayed to other spacecraft (cars). An object of the paper is to provide a method for improving a stuck phenomenon. The paper presents first a formation stuck is caused by a kind of resonance whose characteristic frequency is common among the spacecraft (car drivers). The stuck or traffic congestion could occur even if there is no particular obstacles existing in space (or on the highway). A stuck appears in the formation control between the spacecraft that constitute the constellation in space, when a priori distance control is introduced. This paper provides a method and a device, which is, in one hand, implemented as a individual (or man-machine) system in which the operations are shared such that a spacecraft (a driver) takes in charge of an interval distance and speed control, while on the other hand a quantity of control for stabilizing the formation is calculated automatically and additionally incorporated in respective spacecraft (vehicles). The stabilization of the interval can be realized by employing the distributed control method in which a set of acceleration and deceleration information from a spacecraft (a vehicle) traveling ahead is appropriately integrated and transmitted in relay to a following spacecraft (vehicle). This enables the stabilization of the interval without requiring the interval measurement in itself and leads to the easy installation of equipment. The proposed control provides an interval control as well as a stabilization control of a traffic volume in double layered structure, including a solution for eliminating the formation stuck (traffic congestion). The paper theoretically derives the phenomenon and presents a new control law. And the presentation gives an actual experiment result showing the usefulness of the proposed strategy. Most of the flight mechanics engineers tend to believe the interval distance will maintain the formation. However, it is not true in such decentralized control systems. Local stability does not guarantee the entire stability. The significance of this paper stresses the layered or relayed control mechanism should appear to stabilize the formation.
- Abstract document
- Manuscript document
IAC-06-C1.8.02.pdf (🔒 authorized access only).
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