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guidance, flight mechanics and trajectory optimization

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But from (2.4.155B) it follows that the quantity~(x,L()+C~~~(;t,u)c-<br />

has a minimum of u=uopt <strong>and</strong> that this minimum value is‘lero. IFU<br />

is held fixed at its optimum value which. corresponds to some point(z,2)<br />

{ia +t = u,,t (*,,!I] then this bracketed quantity, considered as a function<br />

of x,t, will have a minimum at the point f, z . Hence,<br />

Z=x^<br />

=0 f=/,n<br />

<strong>and</strong> substituting this expression into (2.4.157), yields the desired result;<br />

namely,<br />

d'=-<br />

df<br />

The fourth condition follows directly from the original assumption on the<br />

R function needed to develop the Bellman equation. This assumption [see<br />

(2.4.W)] re q uired that the second derivatives of R be bounded; hence,<br />

the first derivatives must be continuous. Thus,<br />

<strong>and</strong> condition (4) is satisfied. As discussed at the start of this section,<br />

this requirement in the second derivative s is not always satisfied, a point<br />

which will be treated later on.<br />

The conditions of the Maximum Principle as developed from the Bellman<br />

equation <strong>and</strong> represented in (2.4.152) to (2.4.155) will now be used to<br />

solve the first example problem in Section (2.4.8).<br />

The <strong>guidance</strong> problem of Section (2.4.8) is represented by the equations<br />

101<br />

ae<br />

(2.4.160)

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