The rsm_additions package includes plugins for the Robot Statemachine and exemplary launch files
- Maintainer status: maintained
- Maintainer: Marco Steinbrink <marco.stb1993 AT gmail DOT com>
- Author: Marco Steinbrink <marco.stb1993 AT gmail DOT com>
- License: BSD
- Bug / feature tracker: https://github.com/MarcoStb1993/robot_statemachine/issues
- Source: git https://github.com/MarcoStb1993/robot_statemachine.git (branch: master)
Additions to the RSM including all mandatory plugin states and a plugin routine state. Also an additional service provider is included
This package implements plugins for the Calculate Goal State, the Navigation State and the Mapping State. Furthermore, the Reversing Routine State is an optional routine state plugin. The Additions Service Provider handles the data to be transferred between these plugins.
Calculate Goal State
The Calculate Goal State interfaces the ROS package explore_lite, subscribes to its visualization topic that shows frontiers on a 2D map and extracts the closest frontier center point to the robot as navigation goal. Therefore, it retrieves the robot's pose and calculates its distance to each of the frontier's center points. Also, previously failed goals are disregarded as potential navigation goals. If it fails to find a suitable goal for exploration, it returns an error message and transitions back to the Idle State
To have explore_lite running without directly sending commands to the navigation stack, a mock action server is constructed in the Additions Service Provider that leads the exploration to believe the goals are accepted. Otherwise it does not start to to calculate frontiers. Furthermore, explore_lite is launched with progress_timeout set to 3600 seconds which gives the robot ten hours to move, otherwise the exploration stops and needs to be relaunched.
The Navigation State realizes an interface to the navigation ROS package. It forwards received goals to the navigation stack and also gets feedback from it regarding the progress. If it fails, the goal is added to the failed goals list. If it succeeds, the failed goal list will be reset.
When standing still for too long, it transitions to the Idle State. Reaching the goal will initiate a transition to the Mapping State or the particular routine state if there is one available. If not, Waypoint Following State is called. After reaching a navigation goal provided by RViz and if waypoint following has ended, it transitions to Idle State.
Reverse driving is realised by running two navigation stacks, one for forward driving and one for reverse driving. This is explained in more detail later. For reverse driving the robot also features a transform to a reverse base frame. When driving in reverse, all output command velocities are negated by the Additions Service Provider. If the reverse mode is activated or deactivated, the goal is cancelled and sent to the reverse navigation.
There are two mapping plugins included. The first state is just a dummy state while the latter is swiveling a simulated kinect camera from left to right around a revoluting joint.
Mapping Dummy State
The Mapping Dummy State is just transitioning back to the Calculate Goal State as specific mapping procedures are only relevant for the particular robot.
Kinect Mapping State
Swivels a kinect camera mounted on a joint revoluting around the z-axis from left to right and back to its centered position to map the surrounding area. This only works for the implemented Gazebo simulation as it publishes commands to the joint the kinect is mounted on.
Reversing Routine State
A Routine State called Reversing Routine is also include and toggles the reverse mode when the routine is executed. This means the robot is driving in reverse when it was going forward before and vice versa.
Additions Service Provider
This data handler class retrieved the frontiers published by explore_lite for visualization, extracts each frontier's center and republishes them as possible exploration goals.
For driving in reverse mode, the velocity commands issued by the reverse navigation stack are also subscribed to and republished with negated linear velocities. It also provides a service that is called when reverse mode should be activated. Since nothing needs to be changed in the configuration to change to reverse mode, this service just replies that it was successful.
If the kinect mapping is interrupted, a service is provided that moves the camera back to its centered position while the RSM is continuing.
Reverse Robot Movement with the Navigation Stack
The following code needs to be included in your launch file (or the nodes launched respectively) to allow the robot to navigate in forward and reverse depending on the set mode:
<node pkg="move_base" type="move_base" respawn="false" name="move_base" output="screen"> ... <param name="global_costmap/robot_base_frame" value="$(arg robot_frame)" /> <param name="local_costmap/robot_base_frame" value="$(arg robot_frame)" /> <remap from="/cmd_vel" to="$(arg autonomy_cmd_vel_topic)" /> </node> <node pkg="move_base" type="move_base" respawn="false" name="move_base_reverse" output="screen"> ... <param name="global_costmap/robot_base_frame" value="$(arg robot_frame)_reverse" /> <param name="local_costmap/robot_base_frame" value="$(arg robot_frame)_reverse" /> <remap from="/cmd_vel" to="$(arg autonomy_cmd_vel_topic)_reverse" /> <remap from="move_base/goal" to="move_base_reverse/goal" /> <remap from="move_base/cancel" to="move_base_reverse/cancel" /> <remap from="move_base/feedback" to="move_base_reverse/feedback" /> <remap from="move_base/status" to="move_base_reverse/status" /> <remap from="move_base/result" to="move_base_reverse/result" /> </node> <node pkg="tf" type="static_transform_publisher" name="base_footprint_reverse" args="0 0 0 3.1415 0 0 (arg robot_frame) $(arg robot_frame)_reverse 10" />
Replace the dots with the usual parameters for the navigation stack. Both packages share the same parameters but for the robot base frame. To use a particular navigation stack, initiate it like in this tutorial and call the action for forward movement with "move_base" and for reverse movement with "move_base_reverse".
additionalServiceProviderNodeAn additional data handler class that adds services to interface the exploration lite and navigation packages.
Subscribed Topics<autonomy_cmd_vel_top>_reverse (std_msgs/String)
- Topic name for the autonomy command velocity in reverse mode
- All frontier grid cells as points and closest frontier points as spheres
Published Topics<_autonomy_cmd_vel_topic> (std_msgs/String)
- Topic name for the autonomy command velocity
- List of all currently available exploration goals
- Position the kinect revolute joint will move to
- Needs to be implemented for reverse mode, just returns success
Parameters~update_frequency (float, default: 20)
- Update rate in Hz
- Topic name for the autonomy command velocity
- Sets the plugin's name for the navigation state
- Sets the plugin's name for the mapping state.