Proxy Robot Model¶
The proxy robot model is a simplification of the wobbly two-wheeled
robot intended for displaying the position of a remote robot using the
delegate robot model. The body has no actuators, sensors, or physics. It
does participate in collisions, acting like a fixed rigid body.
This model is demonstrated in the network-party.wbt world.
Screenshot of Webots model of a diff-drive ‘proxy’ robot.¶
proxy.proto¶
The robot model has been encapsulated in a .proto file for easy reuse. The model includes user-accessible scaling and color parameters.
1#VRML_SIM R2022a utf8
2# Proxy robot body to represent a remote robot, based on the wobbly robot body.
3# This robot has no physics but is positioned by a delegate in response to
4# position data reported over the network.
5# documentation url: https://courses.ideate.cmu.edu/16-375
6# license: No copyright, 2020-2022 Garth Zeglin. This file is explicitly placed in the public domain.
7PROTO proxy [
8 field SFVec3f translation 0 0 0
9 field SFRotation rotation 0 1 0 0
10 field SFString controller ""
11 field SFString name "proxy"
12 field SFFloat wheelRadius 0.1
13 field SFFloat axleLength 0.14
14 field SFColor bodyColor 0.8 0.8 0.8
15 field SFColor wheelColor 0.3 0.3 0.3
16 field SFString customData ""
17]
18{
19 Robot {
20 # connect properties to user-visible data fields
21 translation IS translation
22 rotation IS rotation
23 controller IS controller
24 name IS name
25 customData IS customData
26
27 # calculate derived parameters
28 %{
29 local counterweightHeight = fields.wheelRadius.value
30 local counterweightOffset = 0.75*fields.wheelRadius.value
31 local counterweightTop = 1.25*fields.wheelRadius.value
32 local sensorHeight = 3*fields.wheelRadius.value
33 local stalkHeight = sensorHeight - counterweightTop
34 local stalkOffset = counterweightTop + 0.5*stalkHeight
35 }%
36
37 children [
38 # The body group contains three cylinders: the massive counterweight at
39 # bottom, a thin stalk rising above it, topped by the sensor disc.
40 # All these shapes participate in collision; the axle is kept separate
41 # as it is just for rendering.
42 DEF bodyShape Group {
43 children [
44 # counterweight
45 Transform {
46 translation 0 0 %{= counterweightOffset }%
47 rotation 1 0 0 0
48 children [
49 Shape {
50 appearance DEF bodyAppearance PBRAppearance {
51 baseColor IS bodyColor
52 roughness 0.5
53 metalness 0.5
54 }
55
56 geometry Cylinder {
57 height %{= counterweightHeight }%
58 radius 0.05
59 }
60 }
61 ]
62 }
63 # sensor disc
64 Transform {
65 translation 0 0 %{= sensorHeight }%
66 rotation 1 0 0 0
67 children [
68 Shape {
69 appearance USE bodyAppearance
70 geometry Cylinder {
71 height 0.01
72 radius 0.025
73 }
74 }
75 ]
76 }
77 # stalk
78 Transform {
79 translation 0 0 %{= stalkOffset }%
80 rotation 1 0 0 0
81 children [
82 Shape {
83 appearance USE bodyAppearance
84 geometry Cylinder {
85 height %{= stalkHeight }%
86 radius 0.01
87 }
88 }
89 ]
90 }
91 ]
92 }
93 # Visible axle shape, not part of the boundingObject.
94 DEF axleShape Transform {
95 translation 0 0 %{= fields.wheelRadius.value }%
96 rotation 1 0 0 1.5707963267948966
97 children [
98 Shape {
99 appearance USE bodyAppearance
100 geometry Cylinder {
101 height %{= fields.axleLength.value + 0.02 }%
102 radius 0.005
103 }
104 }
105 ]
106 }
107 # Define the left wheel axis, pointing in the +Y direction along the axle.
108 HingeJoint {
109 jointParameters HingeJointParameters {
110 axis 0 1 0
111 anchor 0 0 %{= fields.wheelRadius.value }%
112 }
113 # Define the left wheel solid, offset along +Y along the axle.
114 endPoint DEF leftWheel Solid {
115 translation 0 %{= 0.5*fields.axleLength.value }% %{= fields.wheelRadius.value }%
116 rotation -1 0 0 1.5707963267948966
117 children [
118 # Define the left wheel shape and appearance, which is used by the right wheel solid.
119 DEF wheelShape Transform {
120 rotation 0 0 1 0
121 children [
122 Shape {
123 appearance PBRAppearance {
124 baseColor IS wheelColor
125 roughness 0.5
126 metalness 0.5
127 }
128 geometry Cylinder {
129 height 0.01
130 radius %{= fields.wheelRadius.value }%
131 }
132 }
133 ]
134 }
135 ]
136 name "left wheel"
137 boundingObject USE wheelShape
138 }
139 }
140 # Define the right wheel axis, also pointing in the +Y direction along the axle
141 # so positive wheel rotations will move forward.
142 HingeJoint {
143 jointParameters HingeJointParameters {
144 axis 0 1 0
145 anchor 0 0 %{= fields.wheelRadius.value }%
146 }
147 # Define the right wheel solid, offset along -Y along the axle.
148 # The wheel shape is inherited from the left wheel.
149 endPoint DEF rightWheel Solid {
150 translation 0 %{= -0.5*fields.axleLength.value }% %{= fields.wheelRadius.value }%
151 rotation 1 0 0 1.5707963267948966
152 children [
153 USE wheelShape
154 ]
155 name "right wheel"
156 boundingObject USE wheelShape
157 }
158 }
159 ] # close children list of Robot
160 boundingObject USE bodyShape
161 } # close Robot
162}