Buoyancy engine

examples/worlds/buoyancy_engine.sdf

@@ -0,0 +1,142 @@
+<?xml version="1.0" ?>
+<!--
+This example shows you how to use the BuoyancyEngine system to
+control the buoyancy of an underwater glider. It uses Archimedes'
+principle to apply an upward force based on the volume of the bladder. It
+listens to the topic `buoyancy_engine` or
+/model/{namespace}/buoyancy_engine` topic for the volume of the bladder in
+*cubicmeters*.
+## Parameters
+<link_name> - The link which the plugin is attached to [required, string]
+<namespace> - The namespace for the topic. If empty the plugin will listen
+  on `buoyancy_engine` otherwise it listens on
+  `/model/{namespace}/buoyancy_engine` [optional, string]
+<min_volume> - Minimum volume of the engine [optional, float,
+  default=0.00003m^3]
+<neutral_volume> - At this volume the engine has neutral buoyancy. Used to
+  estimate the weight of the engine [optional, float, default=0.0003m^3]
+<default_volume> - The volume which the engine starts at [optional, float,
+  default=0.0003m^3]
+<max_volume> - Maximum volume of the engine [optional, float,
+  default=0.00099m^3]
+<max_inflation_rate> - Maximum inflation rate for bladder [optional,
+  float, default=0.000003m^3/s]
+<fluid_density> - The fluid density of the liquid its suspended in kgm^-3.
+  [optional, float, default=1000kgm^-3]
+## Topics
+* Subscribes to a ignition::msgs::Double on `buoyancy_engine` or
+ `/model/{namespace}/buoyancy_engine`. This is the set point for the
+ engine.
+* Publishes a ignition::msgs::Double on `buoyancy_engine` or
+ `/model/{namespace}/buoyancy_engine/current_volume` on the current volume
+## Examples
+To get started run:
+```
+ign gazebo buoyancy_engine.sdf
+```
+Enter the following in a separate terminal:
+```
+ign topic -t  /model/buoyant_box/buoyancy_engine/ -m ignition.msgs.Double
+   -p "data: 0.003"
+```
+To see the box float up.
+```
+ign topic -t  /model/buoyant_box/buoyancy_engine/ -m ignition.msgs.Double
+   -p "data: 0.001"
+```
+To see the box go down.
+To see the current volume enter:
+```
+ign topic -t  /model/buoyant_box/buoyancy_engine/current_volume -e
+```
+-->
+<sdf version="1.6">
+  <world name="buoyant_tethys">
+    <scene>
+      <!-- For turquoise ambient -->
+      <ambient>0.0 1.0 1.0</ambient>
+      <background>0.0 0.7 0.8</background>
+    </scene>
+
+    <physics name="1ms" type="ode">
+      <max_step_size>0.001</max_step_size>
+      <real_time_factor>1.0</real_time_factor>
+    </physics>
+    <plugin
+      filename="ignition-gazebo-physics-system"
+      name="ignition::gazebo::systems::Physics">
+    </plugin>
+    <plugin
+      filename="ignition-gazebo-user-commands-system"
+      name="ignition::gazebo::systems::UserCommands">
+    </plugin>
+    <plugin
+      filename="ignition-gazebo-scene-broadcaster-system"
+      name="ignition::gazebo::systems::SceneBroadcaster">
+    </plugin>
+    <plugin
+      filename="ignition-gazebo-contact-system"
+      name="ignition::gazebo::systems::Contact">
+    </plugin>
+
+    <plugin
+      filename="ignition-gazebo-buoyancy-system"
+      name="ignition::gazebo::systems::Buoyancy">
+      <uniform_fluid_density>1000</uniform_fluid_density>
+    </plugin>
+
+    <light type="directional" name="sun">
+      <cast_shadows>true</cast_shadows>
+      <pose>0 0 10 0 0 0</pose>
+      <diffuse>1 1 1 1</diffuse>
+      <specular>0.5 0.5 0.5 1</specular>
+      <attenuation>
+        <range>1000</range>
+        <constant>0.9</constant>
+        <linear>0.01</linear>
+        <quadratic>0.001</quadratic>
+      </attenuation>
+      <direction>-0.5 0.1 -0.9</direction>
+    </light>
+
+    <model name="buoyant_box">
+      <pose>0 0 0 0 0 0</pose>
+      <link name='body'>
+        <inertial>
+          <mass>1000</mass>
+          <inertia>
+            <ixx>133.3333</ixx>
+            <iyy>133.3333</iyy>
+            <izz>133.3333</izz>
+          </inertia>
+        </inertial>
+        <visual name='body_visual'>
+          <geometry>
+            <box>
+              <size>1 1 1</size>
+            </box>
+          </geometry>
+        </visual>
+        <collision name='body_collision'>
+          <geometry>
+            <box>
+              <size>1 1 1</size>
+            </box>
+          </geometry>
+        </collision>
+      </link>
+      <plugin
+        filename="libignition-gazebo-buoyancy-engine-system.so"
+        name="ignition::gazebo::systems::BuoyancyEngine">
+        <link_name>body</link_name>
+        <namespace>buoyant_box</namespace>
+        <min_volume>0.0</min_volume>
+        <neutral_volume>0.002</neutral_volume>
+        <default_volume>0.002</default_volume>
+        <max_volume>0.003</max_volume>
+        <max_inflation_rate>0.0003</max_inflation_rate>
+      </plugin>
+
+    </model>
+  </world>
+</sdf>

src/systems/CMakeLists.txt

@@ -92,6 +92,7 @@ add_subdirectory(apply_joint_force)
 add_subdirectory(battery_plugin)
 add_subdirectory(breadcrumbs)
 add_subdirectory(buoyancy)
+add_subdirectory(buoyancy_engine)
 add_subdirectory(collada_world_exporter)
 add_subdirectory(contact)
 add_subdirectory(camera_video_recorder)