Dynamically creating objects

Objects

The objects are models including basic and custom forms that can be spawned in the simulation.

from pcg_gazebo.simulation import create_object

# If there is a Gazebo instance running, you can spawn the box into the simulation
from pcg_gazebo.task_manager import Server
# First create a simulation server
server = Server()
# Create a simulation manager named default
server.create_simulation('default')
simulation = server.get_simulation('default')
# Run an instance of the empty.world scenario
# This is equivalent to run
#      roslaunch gazebo_ros empty_world.launch
# with all default parameters
simulation.create_gazebo_empty_world_task()
# A task named 'gazebo' the added to the tasks list
print(simulation.get_task_list())
# But it is still not running
print('Is Gazebo running: {}'.format(simulation.is_task_running('gazebo')))
# Run Gazebo
simulation.run_all_tasks()

['gazebo']
Is Gazebo running: False

from pcg_gazebo.generators import WorldGenerator
import random
# Create a Gazebo proxy
gazebo_proxy = simulation.get_gazebo_proxy()

# Use the generator to spawn the model to the Gazebo instance running at the moment
generator = WorldGenerator(gazebo_proxy=gazebo_proxy)

Geometries

Box

box = create_object('box')
# A box object comes initially with no inertial information and null size.
print('Size:')
print(box.size)
print('Inertial:')
print(box.inertial)

Size:
[1, 1, 1]
Inertial:
None

# When generating the SDF elements for the box, a few options can be used
print(box.to_sdf('box'))

<box>
  <size>1 1 1</size>
</box>

print(box.to_sdf('geometry'))

<geometry>
  <box>
    <size>1 1 1</size>
  </box>
</geometry>

print(box.to_sdf('collision'))

<collision name="collision">
  <max_contacts>10</max_contacts>
  <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
  <geometry>
    <box>
      <size>1 1 1</size>
    </box>
  </geometry>
</collision>

print(box.to_sdf('visual'))

<visual name="visual">
  <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
  <geometry>
    <box>
      <size>1 1 1</size>
    </box>
  </geometry>
  <transparency>0.0</transparency>
  <cast_shadows>1</cast_shadows>
</visual>

print(box.to_sdf('link'))

<link name="box">
  <collision name="collision">
    <max_contacts>10</max_contacts>
    <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
    <geometry>
      <box>
        <size>1 1 1</size>
      </box>
    </geometry>
  </collision>
  <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
  <visual name="visual">
    <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
    <geometry>
      <box>
        <size>1 1 1</size>
      </box>
    </geometry>
    <transparency>0.0</transparency>
    <cast_shadows>1</cast_shadows>
  </visual>
</link>

print(box.to_sdf('model'))

<model name="box">
  <link name="box">
    <collision name="collision">
      <max_contacts>10</max_contacts>
      <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
      <geometry>
        <box>
          <size>1 1 1</size>
        </box>
      </geometry>
    </collision>
    <visual name="visual">
      <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
      <geometry>
        <box>
          <size>1 1 1</size>
        </box>
      </geometry>
      <transparency>0.0</transparency>
      <cast_shadows>1</cast_shadows>
    </visual>
  </link>
  <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
  <allow_auto_disable>0</allow_auto_disable>
  <static>0</static>
</model>

# To set the inertial, use the function add_inertial giving the mass of the box,
# the moments of inertia will be computed from the box's dimensions
box.size = [0.3, 0.6, 0.2]
box.add_inertial(mass=20)
print(box.inertial)

Mass [Kg]=20
Pose=[0. 0. 0.]
I =
    Ixx=0.6666666666666666
    Iyy=0.21666666666666665
    Izz=0.7499999999999999
    Ixy=0
    Ixz=0
    Iyz=0

# The inertial information will be added to the SDF description in link and model modes
print(box.to_sdf('link'))
print(box.to_sdf('model'))

<link name="box">
  <collision name="collision">
    <max_contacts>10</max_contacts>
    <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
    <geometry>
      <box>
        <size>0.3 0.6 0.2</size>
      </box>
    </geometry>
  </collision>
  <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
  <inertial>
    <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
    <mass>20.0</mass>
    <inertia>
      <iyz>0.0</iyz>
      <ixy>0.0</ixy>
      <ixz>0.0</ixz>
      <izz>0.7499999999999999</izz>
      <ixx>0.6666666666666666</ixx>
      <iyy>0.21666666666666665</iyy>
    </inertia>
  </inertial>
  <visual name="visual">
    <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
    <geometry>
      <box>
        <size>0.3 0.6 0.2</size>
      </box>
    </geometry>
    <transparency>0.0</transparency>
    <cast_shadows>1</cast_shadows>
  </visual>
</link>

<model name="box">
  <link name="box">
    <collision name="collision">
      <max_contacts>10</max_contacts>
      <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
      <geometry>
        <box>
          <size>0.3 0.6 0.2</size>
        </box>
      </geometry>
    </collision>
    <visual name="visual">
      <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
      <geometry>
        <box>
          <size>0.3 0.6 0.2</size>
        </box>
      </geometry>
      <transparency>0.0</transparency>
      <cast_shadows>1</cast_shadows>
    </visual>
    <inertial>
      <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
      <inertia>
        <iyz>0.0</iyz>
        <ixy>0.0</ixy>
        <ixz>0.0</ixz>
        <izz>0.7499999999999999</izz>
        <ixx>0.6666666666666666</ixx>
        <iyy>0.21666666666666665</iyy>
      </inertia>
      <mass>20.0</mass>
    </inertial>
  </link>
  <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
  <allow_auto_disable>0</allow_auto_disable>
  <static>0</static>
</model>

model_counter = 0
for x in [-5, 0, 5]:
    for y in [-5, 0, 5]:
        box.visual.enable_property('material')
        box.visual.set_xkcd_color()
        generator.spawn_model(
            model=box, 
            robot_namespace='box_{}'.format(model_counter),
            pos=[x, y, 10])
        model_counter += 1

# Using the Gazebo proxy created by the generator's constructor
# it is possible to see that all models were created
print(generator.gazebo_proxy.get_model_names())

['ground_plane', 'box_0', 'box_1', 'box_2', 'box_3', 'box_4', 'box_5', 'box_6', 'box_7', 'box_8']

# End the simulation by killing the Gazebo task
# simulation.kill_task('gazebo')

Sphere

sphere = create_object('sphere')
# A sphere object comes initially with no inertial information and radius equal to 1.
print('Radius:')
print(sphere.radius)
print('Inertial:')
print(sphere.inertial)

Radius:
1
Inertial:
None

# When generating the SDF elements for the box, a few options can be used
print(sphere.to_sdf('sphere'))

<sphere>
  <radius>1.0</radius>
</sphere>

print(sphere.to_sdf('geometry'))

<geometry>
  <sphere>
    <radius>1.0</radius>
  </sphere>
</geometry>

print(sphere.to_sdf('collision'))

<collision name="collision">
  <max_contacts>10</max_contacts>
  <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
  <geometry>
    <sphere>
      <radius>1.0</radius>
    </sphere>
  </geometry>
</collision>

print(sphere.to_sdf('visual'))

<visual name="visual">
  <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
  <geometry>
    <sphere>
      <radius>1.0</radius>
    </sphere>
  </geometry>
  <transparency>0.0</transparency>
  <cast_shadows>1</cast_shadows>
</visual>

print(sphere.to_sdf('link'))

<link name="sphere">
  <collision name="collision">
    <max_contacts>10</max_contacts>
    <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
    <geometry>
      <sphere>
        <radius>1.0</radius>
      </sphere>
    </geometry>
  </collision>
  <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
  <visual name="visual">
    <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
    <geometry>
      <sphere>
        <radius>1.0</radius>
      </sphere>
    </geometry>
    <transparency>0.0</transparency>
    <cast_shadows>1</cast_shadows>
  </visual>
</link>

print(sphere.to_sdf('model'))

<model name="sphere">
  <link name="sphere">
    <collision name="collision">
      <max_contacts>10</max_contacts>
      <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
      <geometry>
        <sphere>
          <radius>1.0</radius>
        </sphere>
      </geometry>
    </collision>
    <visual name="visual">
      <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
      <geometry>
        <sphere>
          <radius>1.0</radius>
        </sphere>
      </geometry>
      <transparency>0.0</transparency>
      <cast_shadows>1</cast_shadows>
    </visual>
  </link>
  <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
  <allow_auto_disable>0</allow_auto_disable>
  <static>0</static>
</model>

# To set the inertial, use the function add_inertial giving the mass of the sphere,
# the moments of inertia will be computed from the sphere's dimensions
sphere.radius = 0.3
sphere.add_inertial(20)
print(sphere.inertial)

Mass [Kg]=20
Pose=[0. 0. 0.]
I =
    Ixx=0.72
    Iyy=0.72
    Izz=0.72
    Ixy=0
    Ixz=0
    Iyz=0

# The inertial information will be added to the SDF description in link and model modes
print(sphere.to_sdf('link'))
print(sphere.to_sdf('model'))

<link name="sphere">
  <collision name="collision">
    <max_contacts>10</max_contacts>
    <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
    <geometry>
      <sphere>
        <radius>0.3</radius>
      </sphere>
    </geometry>
  </collision>
  <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
  <inertial>
    <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
    <mass>20.0</mass>
    <inertia>
      <iyz>0.0</iyz>
      <ixy>0.0</ixy>
      <ixz>0.0</ixz>
      <izz>0.72</izz>
      <ixx>0.72</ixx>
      <iyy>0.72</iyy>
    </inertia>
  </inertial>
  <visual name="visual">
    <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
    <geometry>
      <sphere>
        <radius>0.3</radius>
      </sphere>
    </geometry>
    <transparency>0.0</transparency>
    <cast_shadows>1</cast_shadows>
  </visual>
</link>

<model name="sphere">
  <link name="sphere">
    <collision name="collision">
      <max_contacts>10</max_contacts>
      <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
      <geometry>
        <sphere>
          <radius>0.3</radius>
        </sphere>
      </geometry>
    </collision>
    <visual name="visual">
      <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
      <geometry>
        <sphere>
          <radius>0.3</radius>
        </sphere>
      </geometry>
      <transparency>0.0</transparency>
      <cast_shadows>1</cast_shadows>
    </visual>
    <inertial>
      <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
      <inertia>
        <iyz>0.0</iyz>
        <ixy>0.0</ixy>
        <ixz>0.0</ixz>
        <izz>0.72</izz>
        <ixx>0.72</ixx>
        <iyy>0.72</iyy>
      </inertia>
      <mass>20.0</mass>
    </inertial>
  </link>
  <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
  <allow_auto_disable>0</allow_auto_disable>
  <static>0</static>
</model>

# Run Gazebo again, if not already running
simulation.run_task('gazebo')

# Spawn sphere of different values for radius
model_counter = 0
for _ in range(3):
    for _ in range(3):
        sphere.radius = random.random() * 2
        sphere.add_inertial(random.random() * 30)
        sphere.visual.enable_property('material')
        sphere.visual.set_xkcd_color()
        generator.spawn_model(
            model=sphere, 
            robot_namespace='sphere_{}'.format(model_counter),
            pos=[(random.random() - 0.5) * 10, (random.random() - 0.5) * 10, (random.random() - 0.5) * 5 + 3])
        model_counter += 1

# End the simulation by killing the Gazebo task
# simulation.kill_all_tasks()

Cylinder

cylinder = create_object('cylinder')
# A sphere object comes initially with no inertial information, and length and radius equal to 1.
print('Radius:')
print(cylinder.radius)
print('Length:')
print(cylinder.length)

Radius:
1
Length:
1

# When generating the SDF elements for the cylinder, a few options can be used
print(cylinder.to_sdf('cylinder'))

<cylinder>
  <length>1.0</length>
  <radius>1.0</radius>
</cylinder>

print(cylinder.to_sdf('geometry'))

<geometry>
  <cylinder>
    <length>1.0</length>
    <radius>1.0</radius>
  </cylinder>
</geometry>

print(cylinder.to_sdf('collision'))

<collision name="collision">
  <max_contacts>10</max_contacts>
  <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
  <geometry>
    <cylinder>
      <length>1.0</length>
      <radius>1.0</radius>
    </cylinder>
  </geometry>
</collision>

print(cylinder.to_sdf('visual'))

<visual name="visual">
  <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
  <geometry>
    <cylinder>
      <length>1.0</length>
      <radius>1.0</radius>
    </cylinder>
  </geometry>
  <transparency>0.0</transparency>
  <cast_shadows>1</cast_shadows>
</visual>

print(cylinder.to_sdf('link'))

<link name="cylinder">
  <collision name="collision">
    <max_contacts>10</max_contacts>
    <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
    <geometry>
      <cylinder>
        <length>1.0</length>
        <radius>1.0</radius>
      </cylinder>
    </geometry>
  </collision>
  <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
  <visual name="visual">
    <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
    <geometry>
      <cylinder>
        <length>1.0</length>
        <radius>1.0</radius>
      </cylinder>
    </geometry>
    <transparency>0.0</transparency>
    <cast_shadows>1</cast_shadows>
  </visual>
</link>

print(cylinder.to_sdf('model'))

<model name="cylinder">
  <link name="cylinder">
    <collision name="collision">
      <max_contacts>10</max_contacts>
      <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
      <geometry>
        <cylinder>
          <length>1.0</length>
          <radius>1.0</radius>
        </cylinder>
      </geometry>
    </collision>
    <visual name="visual">
      <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
      <geometry>
        <cylinder>
          <length>1.0</length>
          <radius>1.0</radius>
        </cylinder>
      </geometry>
      <transparency>0.0</transparency>
      <cast_shadows>1</cast_shadows>
    </visual>
  </link>
  <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
  <allow_auto_disable>0</allow_auto_disable>
  <static>0</static>
</model>

# To set the inertial, use the function add_inertial giving the mass of the cylinder,
# the moments of inertia will be computed from the cylinder's dimensions
cylinder.radius = 0.3
cylinder.length = 0.8
cylinder.add_inertial(20)
print(cylinder.inertial)

Mass [Kg]=20
Pose=[0. 0. 0.]
I =
    Ixx=1.5166666666666668
    Iyy=1.5166666666666668
    Izz=0.8999999999999999
    Ixy=0
    Ixz=0
    Iyz=0

# The inertial information will be added to the SDF description in link and model modes
print(cylinder.to_sdf('link'))
print(cylinder.to_sdf('model'))

<link name="cylinder">
  <collision name="collision">
    <max_contacts>10</max_contacts>
    <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
    <geometry>
      <cylinder>
        <length>0.8</length>
        <radius>0.3</radius>
      </cylinder>
    </geometry>
  </collision>
  <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
  <inertial>
    <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
    <mass>20.0</mass>
    <inertia>
      <iyz>0.0</iyz>
      <ixy>0.0</ixy>
      <ixz>0.0</ixz>
      <izz>0.8999999999999999</izz>
      <ixx>1.5166666666666668</ixx>
      <iyy>1.5166666666666668</iyy>
    </inertia>
  </inertial>
  <visual name="visual">
    <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
    <geometry>
      <cylinder>
        <length>0.8</length>
        <radius>0.3</radius>
      </cylinder>
    </geometry>
    <transparency>0.0</transparency>
    <cast_shadows>1</cast_shadows>
  </visual>
</link>

<model name="cylinder">
  <link name="cylinder">
    <collision name="collision">
      <max_contacts>10</max_contacts>
      <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
      <geometry>
        <cylinder>
          <length>0.8</length>
          <radius>0.3</radius>
        </cylinder>
      </geometry>
    </collision>
    <visual name="visual">
      <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
      <geometry>
        <cylinder>
          <length>0.8</length>
          <radius>0.3</radius>
        </cylinder>
      </geometry>
      <transparency>0.0</transparency>
      <cast_shadows>1</cast_shadows>
    </visual>
    <inertial>
      <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
      <inertia>
        <iyz>0.0</iyz>
        <ixy>0.0</ixy>
        <ixz>0.0</ixz>
        <izz>0.8999999999999999</izz>
        <ixx>1.5166666666666668</ixx>
        <iyy>1.5166666666666668</iyy>
      </inertia>
      <mass>20.0</mass>
    </inertial>
  </link>
  <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
  <allow_auto_disable>0</allow_auto_disable>
  <static>0</static>
</model>

# Run Gazebo again, if not already running
simulation.run_task('gazebo')

# Spawn sphere of different values for radius
model_counter = 0
for _ in range(3):
    for _ in range(3):
        cylinder.length = random.random() * 3
        cylinder.radius = random.random() * 0.5
        cylinder.add_inertial(random.random() * 30)
        cylinder.visual.enable_property('material')
        cylinder.visual.set_xkcd_color()
        generator.spawn_model(
            model=cylinder, 
            robot_namespace='cylinder_{}'.format(model_counter),
            pos=[(random.random() - 0.5) * 10, (random.random() - 0.5) * 10, (random.random() - 0.5) * 5 + 10])
        model_counter += 1

Plane

plane = create_object('plane')
# A plane per default has normal [0, 0, 1] and size = [1, 1]
print('Normal:')
print(plane.normal)
print('Size:')
print(plane.size)

Normal:
[0, 0, 1]
Size:
[1, 1]

# When generating the SDF elements for the plane, a few options can be used
print(plane.to_sdf('plane'))

<plane>
  <normal>0 0 1</normal>
  <size>1 1</size>
</plane>

print(plane.to_sdf('geometry'))

<geometry>
  <plane>
    <normal>0 0 1</normal>
    <size>1 1</size>
  </plane>
</geometry>

print(plane.to_sdf('visual'))

<visual name="visual">
  <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
  <geometry>
    <plane>
      <normal>0 0 1</normal>
      <size>1 1</size>
    </plane>
  </geometry>
  <transparency>0.0</transparency>
  <cast_shadows>1</cast_shadows>
</visual>

print(plane.to_sdf('collision'))

<collision name="collision">
  <max_contacts>10</max_contacts>
  <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
  <geometry>
    <plane>
      <normal>0 0 1</normal>
      <size>1 1</size>
    </plane>
  </geometry>
</collision>

print(plane.to_sdf('link'))

<link name="plane">
  <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
  <visual name="visual">
    <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
    <geometry>
      <plane>
        <normal>0 0 1</normal>
        <size>1 1</size>
      </plane>
    </geometry>
    <transparency>0.0</transparency>
    <cast_shadows>1</cast_shadows>
  </visual>
</link>

print(plane.to_sdf('model'))

<model name="plane">
  <link name="plane">
    <visual name="visual">
      <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
      <geometry>
        <plane>
          <normal>0 0 1</normal>
          <size>1 1</size>
        </plane>
      </geometry>
      <transparency>0.0</transparency>
      <cast_shadows>1</cast_shadows>
    </visual>
  </link>
  <pose frame="">0 0 0 0.0 -0.0 0.0</pose>
  <allow_auto_disable>0</allow_auto_disable>
  <static>1</static>
</model>

# Run Gazebo again, if not already running
simulation.run_task('gazebo')

# Spawning the plane
# When there are other models in the simulation, 
# the spawning of a new plane with [0, 0, 1] and a plane as 
# collision geometry  leads to 
# the new plane becoming the ground plane
# To set the collision geometry, use
#    plane.generate_collision = True
plane = create_object('plane')
plane.size = [random.random() * 5, random.random() * 5]
p = random.random()
plane.normal = [0, 0, 1]
plane.visual.enable_property('material')
plane.visual.set_xkcd_color()
generator.spawn_model(
    model=plane, 
    robot_namespace='new_plane',
    pos=[(random.random() - 0.5) * 10, (random.random() - 0.5) * 10, (random.random() - 0.5) * 2 + 5])

True

The output should look like this