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Changes for page Ball Physics

Last modified by Soeren Domroes on 2025/01/30 12:18
From version 12.1
edited by stu104225
on 2020/03/09 11:13
Change comment: There is no comment for this version
To version 5.1
edited by stu104225
on 2020/03/04 17:18
Change comment: There is no comment for this version

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1 -The **ball physics model**'s main objective is to provide a point in time to the controller, when the ball is predicted to be hittable, in order to not let the ball fall into the drain.
2 -The code for what is described in this section can be found in the files "physics.cpp" and "physics.h".
1 +The **ball physics model** is meant to do things ... [TODO]
3 3  
3 +\\
4 4  
5 5  
6 +
6 6  {{toc/}}
7 7  
8 8  == Ball trajectory ==
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9 9  
10 10  ----
11 11  
12 -The trajectory of a ball can be modeled to be parabolic. From two point //p// and //p_old// with corresponding timestamps, the velocity //v// is computed.
13 -For a future point in time //t//, with //t=0 //being the timestamp of// p//, we can then approximately approximately predict the corresponding ball position using the following formulas.
13 +The trajectory of a ball can be modeled to be parabolic.
14 +\\\\\\like so: .... [TODO]
14 14  
15 -[[image:attach:Bildschirmfoto von 2020-03-07 12-21-22.png]]
16 -
17 -The incline of the playfield causes a vertical acceleration, which is modeled via a graviatational pull with the factor //g = sin(6°) * 9.81 m/s²//.
18 -The value of 6° is the incline of the playfield  measured on the physical device.
19 -
20 -== Prediction ==
21 -
22 -----
23 -
24 -The controller calls the function //full_prediction// passing it two subsequent ball positions with timestamps. From these a ball trajectory is infered as described above.
25 -Along the trajectory future times  are stepwisetested for whether the corresponding predicted position is in the flipper range.
26 -Once a position inside the flipper range is found the search is contiunued both forwards and backwards in smaller steps in order to find a good enough estimate of the first and last possible time to hit the ball.
27 -If the trajectory does not intersect the flipper range within a certain prediction frame (see below "**Prediction parameters**") a value far enough into the future is returned, that will be overwritten by subsequent predictions.
28 -
29 -With the current configuration the controller uses the middle point in time between the first and last possible time in order to be most positive to hit the ball.
30 -The computed velocity is also passed to the controller and used is some more advanced  tactical decisions like catching balls.
31 -
32 32  == Configuration ==
33 33  
34 34  ----
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35 35  
36 36  === Prediction parameters ===
37 37  
38 -(% class="wrapped" %)
39 39  |=(((
40 40  Parameter
41 41  )))|=(((
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68 68  10
69 69  )))
70 70  
71 -When setting the PREDICTION_FRAME keep in mind, that predictions, that reach multiple frames into the future, are likely to be overwritten, when new frames arrive and new predictions are calculated.
72 -Nevertheless it is reasonable to calculate predictions beyond the next frame in case a ball is not recognized on the next frame.
54 +with the default values up to 7 predictions are calculated if the ball is not predicted to be in flipper range roughly within the next two frames.
73 73  
74 -With the default values up to 7 predictions are calculated if the ball is not predicted to be in flipper range roughly within the next two frames.
56 +\\
75 75  
76 -The REFINEMENT_FACTOR is also the worst case number of predictions calculated during the reverse search part of the prediction process.
58 +So this number is also the worst case number of predictions calculated during the reverse search part of the prediction process.
77 77  
78 78  \\
79 79  
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134 134  A ball is considered to be in an inlane, when it is in a rectangualar area, with one edge given by the begin of the flipper
135 135  and the other by a point at highest, outermost position of the angled part of the inlane.
136 136  
137 -In this area the vertical accelleration is deactivated in the prediction, since it would cause the prediction to assume the would slide into the wall.
138 -Though in reality the still is some accelleration, a simple linear prediction has shown to be practical in this less critical area.
139 -
140 140  [[image:attach:physics_inlane.png]]
Confluence.Code.ConfluencePageClass[0]
Id
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1 -73072930
1 +71401643
URL
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1 -https://rtsys.informatik.uni-kiel.de/confluence//wiki/spaces/PP18/pages/73072930/Ball Physics
1 +https://rtsys.informatik.uni-kiel.de/confluence//wiki/spaces/PP18/pages/71401643/Ball Physics