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Changes for page Ball Physics

Last modified by Soeren Domroes on 2025/01/30 12:18
From version 9.1
edited by stu104225
on 2020/03/07 12:25
Change comment: There is no comment for this version
To version 4.1
edited by stu104225
on 2020/03/04 16:26
Change comment: There is no comment for this version

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Content
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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 -
3 3  \\
4 4  
5 -\\
3 +== Task ==
6 6  
5 +The ball physics model is meant to do things ...
7 7  
8 -
9 -{{toc/}}
10 -
11 11  == Ball trajectory ==
12 12  
13 -----
9 +The trajectory of a ball can be modeled to be parabolic.
14 14  
15 -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.
16 -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.
17 -
18 -[[image:attach:Bildschirmfoto von 2020-03-07 12-21-22.png]]
19 -
20 -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//.
21 -The value of 6° is the incline of the playfield  measured on the physical device.
22 -
23 23  == Configuration ==
24 24  
25 -----
13 +=== Points of interest ===
26 26  
27 -=== Prediction parameters ===
28 -
29 -(% class="wrapped" %)
30 -|=(((
31 -Parameter
32 -)))|=(((
33 -Description
34 -)))|=(((
35 -Default value
36 -)))
37 -|(((
38 -PREDICTION_FRAME
39 -)))|(((
40 -window size for prediction - How far
41 -
42 -into the future are predctions calculated at most.
43 -)))|(((
44 -70ms
45 -)))
46 -|(((
47 -PREDICTION_STEP_SIZE
48 -)))|(((
49 -size of the steps for the forward search
50 -)))|(((
51 -10ms
52 -)))
53 -|(((
54 -REFINEMENT_FACTOR
55 -)))|(((
56 -The prediction step size for the reverse search is
57 -PREDICTION_STEP_SIZE divided by REFINEMENT_FACTOR.
58 -)))|(((
59 -10
60 -)))
61 -
62 -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.
63 -Nevertheless it is reasonable to calculate predictions beyond the next frame in case a ball is not recognized on the next frame.
64 -
65 -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.
66 -
67 -The REFINEMENT_FACTOR is also the worst case number of predictions calculated during the reverse search part of the prediction process.
68 -
69 -\\
70 -
71 -=== Flipper range ===
72 -
73 73  The model of the area, where the the flippers can hit a ball is computed from a set of five points. These points are set to real world coordinates in meter
74 74  
75 75  and should not need further adjustment after the camera is correctly calibrated (see [[doc:World Coordinate System]]).
76 76  
77 -The values for the left flipper are set to be symmetrical.
78 -
79 79  [[image:attach:physics_points.png]]
80 80  
81 -(% class="wrapped" %)
82 82  |=(((
83 83  Point#
84 84  )))|=(((
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112 112  
113 113  \\
114 114  
115 -From these points an area, where the ball is deemed to be hittable, is computed.
54 +=== Flipper range ===
116 116  
56 +From the aforementioned points
57 +
58 +\\
59 +
60 +\\
61 +
62 +\\
63 +
117 117  [[image:attach:physics2.png]]
118 118  
119 119  \\
... ... @@ -120,12 +120,32 @@
120 120  
121 121  === Inlane Area ===
122 122  
123 -Since the trajectory prediction does not consider collisions in general, we need a different kind of predictions for the inlanes,
124 -i.e. the path feeding a falling ball from the playfield to the flippers, behind the slingshot.
125 -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
126 -and the other by a point at highest, outermost position of the angled part of the inlane.
70 +\\
127 127  
128 -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.
129 -Though in reality the still is some accelleration, a simple linear prediction has shown to be practical in this less critical area.
130 -
131 131  [[image:attach:physics_inlane.png]]
73 +
74 +\\
75 +
76 +=== Prediction parameters ===
77 +
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79 +
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81 +
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Confluence.Code.ConfluencePageClass[0]
Id
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1 -71401661
1 +71401641
URL
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1 -https://rtsys.informatik.uni-kiel.de/confluence//wiki/spaces/PP18/pages/71401661/Ball Physics
1 +https://rtsys.informatik.uni-kiel.de/confluence//wiki/spaces/PP18/pages/71401641/Ball Physics