add ROS middleware examples

examples/middlewares/bullet_ros_control_gazebo.py

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+# -*- coding: utf-8 -*-
 #!/usr/bin/env python
 """Test the publisher using Gazebo with ROS control and Pybullet
 

examples/middlewares/bullet_ros_publisher.py

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+# -*- coding: utf-8 -*-
+#!/usr/bin/env python
+"""Example on how to use the Bullet-ROS simulator (the publisher version) in PRL.
+
+The publisher version publish the various data on the corresponding topics every time the joints are set. If the
+:attr:`teleoperate` is set to True, it will also publish every time we call a `get_*()` method.
+
+Before running this file, run in the terminal:
+```bash
+$ roscore               # note that roscore is launched automatically by this file if has not already been launched
+$ rostopic list         # to show the list of published topics
+```
+
+The last command should print the following:
+```bash
+/rosout
+/rosout_agg
+```
+
+Now, run this file and check the published topics again:
+```bash
+$ rostopic list
+```
+
+This time, you should get as well:
+```bash
+/rosout
+/rosout_agg
+/rrbot/joint_states
+```
+
+You can print the output of the topic with:
+```bash
+$ rostopic echo /rrbot/joint_states
+```
+
+Try to move the robot with the mouse, and see that the published joint position values changed as well.
+
+You can run this code in parallel with `bullet_ros_subscriber.py`, which implements the subscriber version, that is,
+it listens to the topics and set them in the bullet simulator. So by moving the robot in this simulator, you should
+see that it also moves in the other simulator.
+
+Note: this code also works with other robots.
+"""
+
+from itertools import count
+import pyrobolearn as prl
+
+
+# create middleware and simulator (roscore will automatically be launched if it has not already been launched)
+ros = prl.middlewares.ROS(publish=True, teleoperate=True)
+sim = prl.simulators.Bullet(middleware=ros)
+
+# load world
+world = prl.worlds.BasicWorld(sim)
+
+# load robot
+robot = world.load_robot('rrbot')
+
+# run simulation
+for t in count():
+    # get the joint positions from the Bullet simulator (because :attr:`teleoperate` has been set to True,
+    # it will publish these read positions on the corresponding topic)
+    q = robot.get_joint_positions()
+
+    # perform a step in the simulator (and sleep for `sim.dt`)
+    world.step(sim.dt)
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examples/middlewares/bullet_ros_rqt.py

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+# -*- coding: utf-8 -*-
+#!/usr/bin/env python
+"""Test the publisher using PyBullet, ROS, and RQT.
+"""
+
+import pyrobolearn as prl
+
+# create middleware and simulator
+ros = prl.middlewares.ROS(publish=True, teleoperate=True)
+sim = prl.simulators.Bullet(middleware=ros)
+
+# launch RQT
+ros.launch_gui()
+
+# load world
+world = prl.worlds.BasicWorld(sim)
+
+# load robot
+robot = world.load_robot('rrbot')
+
+# run simulation
+for t in prl.count():
+    # get the joint positions from the Bullet simulator (because :attr:`teleoperate` has been set to True,
+    # it will publish these read positions on the corresponding topic)
+    q = robot.get_joint_positions()
+
+    # perform a step in the simulator (and sleep for `sim.dt`)
+    world.step(sim.dt)

examples/middlewares/bullet_ros_subscriber.py

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+# -*- coding: utf-8 -*-
+#!/usr/bin/env python
+"""Example on how to use the Bullet-ROS simulator (the subscriber version) in PRL.
+
+The subscriber version subscribe to various topics related to the loaded robot.
+
+This code works in parallel with the `bullet_ros_publisher.py`, which implements the publisher version, that is,
+it publish to the topics the various data. By moving the robot in the publisher version of the simulator, you should
+see that the robot in this simulator should move in accordance.
+
+Note: this code also works with other robots.
+"""
+
+from itertools import count
+import pyrobolearn as prl
+
+
+# create simulator (ros core will automatically be launched if it has not already been launched)
+ros = prl.middlewares.ROS(subscribe=True, teleoperate=True)
+sim = prl.simulators.Bullet(middleware=ros)
+
+# load world
+world = prl.worlds.BasicWorld(sim)
+
+# load robot
+robot = world.load_robot('rrbot')
+
+# run simulation
+for t in count():
+    # get the joint positions from the ROS subscribers (if possible)
+    robot.get_joint_positions()
+
+    # perform a step in the world, and sleep for `sim.dt`
+    world.step(sim.dt)
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