Accession Number:

ADA048965

Title:

Station Keeping at the L4 Libration Point: A Three-Dimensional Study

Descriptive Note:

Master's thesis

Corporate Author:

AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING

Personal Author(s):

Report Date:

1977-12-01

Pagination or Media Count:

117.0

Abstract:

In this work, the station keeping parameters at the earth-moon libration point, L4, were studied. These equations of motion for the three- dimensional, four body system with elliptical orbits were derived. These equations were then linearized about the L4 point and optimal control theory was applied to obtain a linear feedback controller. The major computations of the controller were associated with the gain matrix, which is the solution to the time varying Riccati equation. Because of the periodic nature of the time varying gains, it was felt that a modified fixed gain control could be used. The modified controller was found by computing the steady-state average of the time varying gains. Several observations were made in studying the performance of the satellite in the vicinity of the L4 point. First, it was found that the modified controller was computationally much simpler than the optimum controller while providing near optimal performance. Second, there is approximately a linear relationship, up to a point, between station keeping cost and distance from the L4 point. Third, there are initial solar configurations which minimize station keeping costs.

Subject Categories:

  • Operations Research
  • Unmanned Spacecraft

Distribution Statement:

APPROVED FOR PUBLIC RELEASE