Tradiotional MEA proof

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Tradiotional MEA proof

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Return to Thread:User talk:Xor/Better MEA formula/Tradiotional MEA proof.

excellent proof! I traped myself in polar coordination and forgot the most important cartesian coordinates;)

Xor (talk)05:09, 25 September 2017
 

I really like this proof!

There is another that you can do, with calculus, so find the escape angle that maximises theta. But that one is more complicated =)

Skilgannon (talk)06:51, 25 September 2017
 

Anyway, the less assumptions you made, the better ;) Do not assume constant speed & direction — use integral instead.

Assume the firing robot sits at the origin, and the target robot sits on the positive x-axis.

Since when hit, <math>y_{bullet} = y_{robot}</math>, we have

<math>\int_{0}^{t_1} v_{bullet} sin(\theta) dt = \int_{0}^{t_1} v_{robot} cos(\alpha) dt</math> where <math>\theta</math> is escape angle, <math>\alpha</math> is retreat angle (the heading of the target robot relating to the y-axis, the direction from y-axis to x-axis is positive).


Since <math>v_{bullet}</math> and <math>\theta</math> is constant, we have

<math>v_{bullet} sin(\theta) t_1 = \int_{0}^{t_1} v_{robot} cos(\alpha) dt</math>


assume <math>v_{robot}</math> is always the max — 8, therefore constant, we have

<math>v_{bullet} sin(\theta) t_1 = v_{robot} \int_{0}^{t_1} cos(\alpha) dt</math>


let <math>\alpha_{0}, \alpha_{2}</math> s.t. <math>cos(\alpha_{0}) \leqslant cos(\alpha) \leqslant cos(\alpha_{2})</math>

there exists <math>\alpha_{1}</math>, <math>cos(\alpha_{0}) \leqslant cos(\alpha_{1}) \leqslant cos(\alpha_{2})</math> s.t. <math>cos(\alpha_{1}) t_1 = \int_{0}^{t_1} cos(\alpha) dt</math>


then we have

<math>v_{bullet} sin(\theta) t_1 = v_{robot} cos(\alpha_1) t_1</math>

<math>v_{bullet} sin(\theta) = v_{robot} cos(\alpha_1)</math>

<math>sin(\theta) = \frac{v_{robot}}{v_{bullet} } cos(\alpha_1)</math>

then we have

<math>\theta_{max} = asin(\frac{v_{robot}}{v_{bullet} })</math>, which can be reached when <math>\alpha_1</math> = 0.

since <math>cos(\alpha) \leqslant cos(0) = 1</math>, <math>\alpha</math> must be always 0, which proved that retreat angle must be always 0.

And we proved that <math>\theta_{max} = asin(\frac{v_{robot}}{v_{bullet} })</math> is true.

Xor (talk)11:24, 25 September 2017
 

I'm still sure that getting slightly away is better both with orbital and traditional one.

Dsekercioglu (talk)08:08, 26 September 2017

Better for what? It does not increase your MEA. Though it decreases the target angular size, so it reduces the probability to be hit. Calculating probability to be hit is yet another beast, which we probably should attempt to solve analytically.

There is another issue, the traditional MEA is good only for a single isolated wave, the real question is how to increase the MEA in a stream of constantly fired bullets.

Beaming (talk)18:59, 26 September 2017

For wave surfers, I think my work is useful — User:Xor/Better_MEA_formula, as the movement is constant with time, it is naturally suitable for multiple waves ;)

Xor (talk)02:15, 27 September 2017

The problem with your formula is that it does not match traditional MEA in the border cases.

The second problem that I not fully understand it. It looks like you are integrating angular velocity to an undefined time t.

Beaming (talk)03:11, 27 September 2017

it matches orbital MEA in border cases though, as always moving perpendicular is impossible, so you have to fallback to orbital ;)

I'm integrating angular velocity from fire time to hit time, which is obviously the escape angle ;) sorry for not saying that clearly in advance, the article is still not finished ;)

Xor (talk)05:49, 27 September 2017
 
 

It increases also. If the formula below is correct, it is true.

asin(sin(a) / (v / 8 - cos(a) / 2))

You can try brute forcing.

Dsekercioglu (talk)10:42, 28 September 2017