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guidance, flight mechanics and trajectory optimization

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the measurement errors could bdd to the fuel cost but under these<br />

conditions would not hinder the eventually successful rendezvous.<br />

The motion analysis in this monograph (Section 2.1) will not go<br />

beyond that of linear terms in the relative coordinates, since these<br />

terms are believed to be adequate for the ranges of relative motions<br />

to be considered. A brief discussion of the possible effects of<br />

perturbations due to air drag, earth oblateness, <strong>and</strong> solar-lunar<br />

gravitation is included in the last portion of Section 2.1.<br />

C. The <strong>trajectory</strong> control problem - Having determined the future course<br />

<strong>and</strong> set up the capability of determining the velocity requirements to<br />

effect rendezvous, a philosophy <strong>and</strong> a procedure to obtain it must be<br />

generated, described, <strong>and</strong> shown to be successful. This development<br />

of the <strong>guidance</strong> scheme is the heart of the problem. Thus, a series<br />

of techniques which have been suggested for this purpose are described<br />

in Section 2.2 (Guidance Equations). The rendezvous which is effected<br />

with any given <strong>guidance</strong> scheme, however, may not be as close as<br />

desired because of errors in the data <strong>and</strong> in the engine performance.<br />

Further, rendezvous will not be optimal unless allowance is made for<br />

the stochastic nature of the problem. Optimization techniques <strong>and</strong><br />

data filtering procedures will thus be important phases of the prob-<br />

lem, <strong>and</strong> these will be described as found in the literature in<br />

Sections 2.3 <strong>and</strong> 2.4, respectively.<br />

For evaluation of the various schemes <strong>and</strong> for assistance in choosing<br />

the state determination process, error analyses are required. The<br />

work that is available in this area will be described in Section 2.4<br />

Finally, in Section 3 suggestions for choosing the specific approaches<br />

for a number of types of systems <strong>and</strong> the definition of interface<br />

problems associated with mid-course orbital transfer or with the<br />

final docking will be discussed.<br />

3

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