Admin: import from robotika.sk

2006-11-30T04:52:28Z

import from robotika.sk

New page

TODO
<ul>
<li>Add friction into Propeller joint - force against momentum</li>
<li>Replace SetMassBox with SetMassSphere with position in correct centre of mass of blade and with radius proportional to area of all triangles multiplied by thickness or blade - constant 0.01</li>
<li>Use triangulation function from openCV</li>
<li></li>
<li>Install OpenCV on WinXP</li>
<li></li>
<li>Start particles only in 2 quadrants - not good... change back or use other model</li>
<li>Other model: create particles in place of collision (see below)</li>
<li>Genom:height of vertices (float string) - enabled/disabled vertices (bitstring)</li>
<li>Make EO alg for rotor shape evolution</li>
<li></li>
<li>Make ParadisEO alg for rotor shape evolution</li>
<li>Test PradisEO alg on at least 2 nodes with pvm</li>
<li>...</li>
</ul>

<h2>Towards speeding up simulation and using correct mass distribution</h2>
''Particles are not flying, just 'hitting' the blades of propeller ''
''Precalculating all needed information before simulation''
----
Random particle creation point
<ol>
<li>Select random triangle from the 3Mesh - proportionally to its size of in-xz-plane-projected area ''probability of selecting particular triangle can be precalculated before simulation loop starts</li>
<li>Project selected triangle into xz plane - <math>\triangle</math> ABC</li>
<li>Calculate coordinates of centre of gravity X of <math>\triangle</math> ABC</li>
<li>Choose 1 triangle out of <math>\triangle</math> ABX, <math>\triangle</math> AXC, <math>\triangle</math> XBC</li>
<li>Calculate another centre of gravity of selected triangle</li>
<li>Repeat 3 previous steps until distance from center of gravity to nearest vertex is less than some epsilon</li>
<li>The final point - translate back to 3D and to relative coordinates of the whole body - rotor</li>
</ol>
----
Centre of Mass of blade
<ol>
<li>Calculate coordinates of centre of gravity and area of each triangle</li>
<li>Repeat until only 1 point - center of gravity of all triangles remains in set </li>
<li>Take 2 triangles (centers of gravity) and calculate their composite center of gravity and respective force (in area units)</li>
</ol>
----
Summary 
Before simulation starts, create following structures and fill it with information
<ul>
<li>Area of projection of each triangle</li>
<li>Centre of gravity of each triangle</li>
<li>Recursively all centres of gravity of all mini-triangles - Estimated count of points = 3depth of recursion x (count of Δ)</li>
<li>anything else?</li>
</ul>
In every simulation step, with roullete wheel /or SUS/<ref>SUS</ref> select one or more triangles and then select random integers from [0, 3depth of recursion) and create sphere objects in that point with velocity vector [0.0, SPEED, 0.0].

After each step destroy all particles

Advantages of above method:
<ul>
<li>Particles are used only for collisions, so they don't live outside of collision</li>
<li>Particles don't hit edges of triangles</li>
<li>Particles are not hit by blade "from the back", thus blade is not slowed down by unwanted collisions</li>
<li>Mass distribution in blade participates in shape evaluation (together with momentum and added joint friction)</li>
<li>Overall speed up</li>
</ul>
Disadvantages of above methof:
<ul>
<li>some extra memory required and precomputation time</li>
</ul>
== Notes ==
<references/>

Issues.../en - Revision history

Admin: import from robotika.sk