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From: bruck@actcom.co.il (Uri Bruck)
Subject: Re: Interception Code
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Date: Mon, 24 Jun 1996 08:08:00 GMT
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nak@gwe486.cb.att.com () wrote:


>>Reasoning:
>[correct reasoning for this limited case deleted]

>Note that we have not in that reasoning addresed the general case of the
>problem where viewing angle is an input, not a known.

The inital viewing angle is input by whatever mechanism you use to
detect the enemy. I see little difference there, unlesss you meant
something else.


>>Note, that in all of the above, the intercept point itself need not be
>>calculated, we can rely entirely on the viewing-angle.

>But it would be cheap once you have the angles settled.  It's the
>intersection point of two lines.  (No trig or sqrt required)

There is no certainty that this would happen until very late in the
chase, or at all.


>>A further (although rather weaker ) result, is that a variation on
>>this method provides a way to add evasive behavior. While the pursuing
>>unit's goal is to lower the rate of change of the viewing angle, the
>>pursued unit's goal is to increase the rate of change of the viewing
>>angle. 

>Sorry, that's not the case always.  A unit would then attempt to inward
>spiral orbit pursuer rather than run away from it.   Highest rate of angle
>change is available at very close range orbit.  The correct response
>would be to turn towards best rate of range increase.

Right. 
Increasing the range is, or course, the best thing to do, althought,
by itself, it does not ensure successful evasion, and, depending on
the relative performance of the two units, may not be always possible.
I  did mention the result as being weaker, but I stand corrected.

So the best response would be to increase the range, and, if possible,
increase the change-rate-of viewing angle as well.
Uri


