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Changes for page Ball Physics

Last modified by Soeren Domroes on 2025/01/30 12:18
From version 3.1
edited by stu104225
on 2020/03/03 18:55
Change comment: There is no comment for this version
To version 8.1
edited by stu104225
on 2020/03/07 11:40
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 +
1 1  \\
2 2  
3 -== Task ==
4 -
5 -The ball physics model is meant to do things ...
6 -
7 7  \\
8 8  
9 -== Configuration ==
10 10  
11 -=== Points of interest ===
12 12  
13 -\\
9 +{{toc/}}
14 14  
15 -[[image:attach:physics_points.png]]
11 +== Ball trajectory ==
16 16  
17 -=== Flipper range ===
13 +----
18 18  
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
19 19  \\
20 20  
21 21  \\
22 22  
23 -\\
21 +[[image:attach:Bildschirmfoto von 2020-03-07 12-21-22.png]]
22 +\\\\like so: .... [TODO]
24 24  
25 -\\
24 +== Configuration ==
26 26  
27 -[[image:attach:physics2.png]]
26 +----
28 28  
29 -\\
28 +=== Prediction parameters ===
30 30  
31 -=== Inlane Area ===
30 +(% class="wrapped" %)
31 +|=(((
32 +Parameter
33 +)))|=(((
34 +Description
35 +)))|=(((
36 +Default value
37 +)))
38 +|(((
39 +PREDICTION_FRAME
40 +)))|(((
41 +window size for prediction - How far
32 32  
33 -[[image:attach:physics_inlane.png]]
43 +into the future are predctions calculated at most.
44 +)))|(((
45 +70ms
46 +)))
47 +|(((
48 +PREDICTION_STEP_SIZE
49 +)))|(((
50 +size of the steps for the forward search
51 +)))|(((
52 +10ms
53 +)))
54 +|(((
55 +REFINEMENT_FACTOR
56 +)))|(((
57 +The prediction step size for the reverse search is
58 +PREDICTION_STEP_SIZE divided by REFINEMENT_FACTOR.
59 +)))|(((
60 +10
61 +)))
34 34  
35 -\\
63 +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.
64 +Nevertheless it is reasonable to calculate predictions beyond the next frame in case a ball is not recognized on the next frame.
36 36  
37 -=== Prediction parameters ===
66 +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.
38 38  
39 -\\
68 +The REFINEMENT_FACTOR is also the worst case number of predictions calculated during the reverse search part of the prediction process.
40 40  
41 41  \\
42 42  
43 -\\
72 +=== Flipper range ===
44 44  
45 -\\
74 +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
46 46  
47 -\\
76 +and should not need further adjustment after the camera is correctly calibrated (see [[doc:World Coordinate System]]).
48 48  
49 -\\
78 +The values for the left flipper are set to be symmetrical.
50 50  
51 -\\
80 +[[image:attach:physics_points.png]]
52 52  
82 +(% class="wrapped" %)
83 +|=(((
84 +Point#
85 +)))|=(((
86 +Description
87 +)))
88 +|(((
89 +1
90 +)))|(((
91 +center point of the circle that the flippers tip moves o
92 +)))
93 +|(((
94 +2
95 +)))|(((
96 +highest point a ball can be at when it hits the resting flipper
97 +)))
98 +|(((
99 +3
100 +)))|(((
101 +lowest point a ball can be at when it hits the resting flipper
102 +)))
103 +|(((
104 +4
105 +)))|(((
106 +lowest point a ball can be at when it hits the fully triggered flipper
107 +)))
108 +|(((
109 +5
110 +)))|(((
111 +highest point a ball can be at when it hits the fully triggered flipper
112 +)))
113 +
53 53  \\
54 54  
116 +From these points an area, where the ball is deemed to be hittable, is computed.
117 +
118 +[[image:attach:physics2.png]]
119 +
55 55  \\
121 +
122 +=== Inlane Area ===
123 +
124 +Since the trajectory prediction does not consider collisions in general, we need a different kind of predictions for the inlanes,
125 +i.e. the path feeding a falling ball from the playfield to the flippers, behind the slingshot.
126 +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
127 +and the other by a point at highest, outermost position of the angled part of the inlane.
128 +
129 +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.
130 +Though in reality the still is some accelleration, a simple linear prediction has shown to be practical in this less critical area.
131 +
132 +[[image:attach:physics_inlane.png]]
Confluence.Code.ConfluencePageClass[0]
Id
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1 -71401639
1 +71401659
URL
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1 -https://rtsys.informatik.uni-kiel.de/confluence//wiki/spaces/PP18/pages/71401639/Ball Physics
1 +https://rtsys.informatik.uni-kiel.de/confluence//wiki/spaces/PP18/pages/71401659/Ball Physics