pioneer_mrs

1. Introduction

A ROS package for Pioneer 3-AT Multi-Robot Systems.

This is a flexible experimental platform for multi-robot systems (MRS). Should there be any problem, please feel free to contact maintainer @hanzheteng or open a new issue in this repository.

ROS package	Description (Features)	Platform
pioneer_mrs	Support scientific computing library (numpy, scipy, etc.) for your algorithms Support two kinds of localization methods (odometry, VICON) Support two kinds of robot-level simulators (MobileSim, Gazebo) Visualization is under developing	Pioneer 3-AT Ubuntu 16.04.3 LTS Robot Operating System (kinetic) ROSARIA package (git-commit-aa8d5f7) ARIA lib (2.9.1a-ubuntu16-i386)

2. Usage

2.1 Running on Robots

System Configuration

Before using this package to drive your robots, you may configure your platform following the steps:

1. All machines (5 robots + 1 laptop) are installed Ubuntu 16.04 and ROS Kinetic
2. All robots (onboard computer, actually) are installed and catkin_make-ed ARIA lib and ROSARIA package
3. All machines need a static IP address and are able to automatically connect to your local WiFi
4. Write the IP and hostname information into /etc/hosts file on all the machines
5. Your commander (laptop) is able to SSH to all robots via public key (instead of password)
6. Onboard computers are able to get access to the microcontroller via serial post (add user to dialout group)

For detailed information regarding how to set up the whole system, please refer to the wiki page.

Moreover, there are two suggestions which is not necessary for this system but may be useful for your development.

• You may install a teamviewer software on your laptop and robots so that you can remote login into your onboard computers.
• For IDE, I recommend RoboWare Studio, which is especially designed for ROS developers. Another alternative is KDevelop, which is a cross-platform IDE.

Package Dependencies

Before git clone this repository, you need to install ARIA lib and git clone ROSARIA package first. After that, catkin_make your ROSARIA package with ARIA library. Then, you can clone this repository by git clone https://github.com/hanzheteng/pioneer_mrs.git and catkin_make this package in your workspace.

Notice:

1. You must catkin_make the ROSARIA package first before you clone and make this package, otherwise it may report errors.
2. Sometimes you need to catkin_make pioneer_mrs_generate_messages first before catkin_make this package, because the compiler may not be able to find the header file of our messages.

Optional package:

• If you want to use VICON motion capture system, you also need to git clone and catkin_make vicon_bridge package.

Sample Usage

Basically there are several steps:

1. launch nodes on all five robots
   roslaunch pioneer_mrs multi-robot.launch
2. launch nodes on commander
   roslaunch pioneer_mrs commander.launch

If using Vicon:

1. launch nodes on all five robots
   roslaunch pioneer_mrs multi-robot.launch pose:=vicon
2. launch nodes on commander
   roslaunch pioneer_mrs commander.launch

2.2 Running on MobileSim Simulator

You also need ROSARIA package to connect to MobileSim simulator. Moreover, you need to install MobileSim on your laptop.

Basically there are several steps:

1. run a MobileSim simulator and spawn five robots
   roslaunch pioneer_mrs mobilesim.launch
2. launch nodes on all five robots
   roslaunch pioneer_mrs multi-robot.launch machine:=mobilesim
3. launch nodes on commander
   roslaunch pioneer_mrs commander.launch

2.3 Running on Gazebo Simulator

You do not need ROSARIA package here, since Gazebo will take charge of publishing odom information and dealing with cmd_vel commands. Gazebo is installed by default along with ROS if choosing desktop-full install. Moreover, for simulations of Pioneer 3-AT robots, you also need models and URDF files supplied by Mobile Robots Inc. by git clone amr-ros-config meta-package.

Basically there are several steps:

1. run a Gazebo simulator and spawn five robots
   roslaunch pioneer_mrs gazebo.launch
2. launch nodes on all five robots
   roslaunch pioneer_mrs multi-robot.launch pose:=gazebo machine:=gazebo
3. launch nodes on commander
   roslaunch pioneer_mrs commander.launch

Notice: On real robots, movement commands only execute for 600ms because of WatchDog timeout mechanism; but in gazebo simulator, robots will keep moving towards the last direction. You may press space bar (stop command) to stop it.

2.4 Single Robot Recoverary

Optional launch file (e.g. robot1):

• launch one robot
  roslaunch pioneer_mrs single-robot.launch hostname:=robot1
• launch one robot with Vicon
  roslaunch pioneer_mrs single-robot.launch hostname:=robot1 pose:=vicon
• launch one robot on MobileSim simulator
  roslaunch pioneer_mrs single-robot.launch hostname:=robot1 machine:=mobilesim
• launch one robot on Gazebo simulator
  roslaunch pioneer_mrs single-robot.launch hostname:=robot1 pose:=gazebo machine:=gazebo

3. Robot Operating System

3.1 ROS Node Info

Note: robot# represents any robot label from 1 to 5.

Node Name	Sub Topic / Srv Client	Pub Topic / Srv Server	Description
/vicon (vicon_bridge package)	---	/vicon/robot#/robot#	publish translation and rotation info
/robot#/RosAria (rosaria package)	/robot#/RosAria/cmd_vel	/robot#/RosAria/pose	SDK bridge to communicate with microcontrollers
/robot#/pioneer_server	/robot#/cmd_vel_hp /robot#/RosAria/pose /robot#/gazebo/odom /vicon/robot#/robot#	/robot#/RosAria/cmd_vel /robot#/get_pose	pose server for pioneer robots
/robot#/algorithm_node	/robot#/comm_state /robot#/get_pose	/robot#/cmd_vel_hp /robot#/Formation	execute pre-designed algorithm
/commander/teleop	/robot#/Formation	/robot#/mission_state /robot#/cmd_vel_hp	commander & teleoperation node
/commander/comm_state_cmd	---	/robot#/comm_state	publish communication graph info

3.2 Message Definition

Topic Name	Format	Message File	Description
vicon/robot#/robot#	std_msgs/Header header string child_frame_id geometry_msgs/Transform transform	TransformStamped.msg	see wiki
/robot#/RosAria/pose	std_msgs/Header header string child_frame_id geometry_msgs/PoseWithCovariance pose geometry_msgs/TwistWithCovariance twist	Odometry.msg	see wiki
/robot#/RosAria/cmd_vel	geometry_msgs/Vector3 linear geometry_msgs/Vector3 angular	Twist.msg	see wiki
/robot#/cmd_vel_hp	float64 x float64 y float64 z	Vector3.msg	only use 2D velocity (z=0)
/robot#/comm_state	bool[5] state	CommunicationState.msg	one row of the communication graph

3.3 Service Definition

Graph Resource Name	Format	Srv File Name	Description
/robot#/get_pose	--- bool success float64 x float64 y float64 theta	Pose2D.srv	same format to geometry_msgs::Pose2D.msg

3.4 Action Definition

Graph Resource Name	Format	Action File Name	Description
/robot#/Formation	uint32 order --- string name float32 x float32 y --- string name float32 x float32 y	Formation.action	set a goal of total steps get feedbacks of positions in each step

4. Update Log

• V1.0 (Jan 4, 2018) Basic multi-robot control framework
• V1.1 (Jan 15, 2018) The MRS control framework works well with new features, but the algorithm node need to be updated.
• V1.1.4 (Feb 5, 2018) The algorithm node works well on both MobileSim simulator and empirical experiments. The Gazebo simulator still has problems to be resolved.
• V1.2 (Feb 18, 2018) The multi-robot system works well on MobileSim simulator, Gazebo simulator and empirical experiments (localization done by either odometry, Vicon system, or Gazebo simulator.)
• V1.3 (Mar 17, 2018) Add offset adjestment to the existing formation based on optimal-point algorithm; Launch files may have some problems because of improper launch sequence. (Senior Design project done in this version)
• V1.4 (Apr 4, 2018) Make this framework more concise and efficient. (Rewrite communication mechanism by client-server RPC; rewrite algorithm node by python and support scientific computing library; apply actionlib for desired missions; add dynamic reconfigure)

5. Debug FAQ

Most of the time, you can use roswtf command to diagnose your problem.

1. If roslaunch or rosrun cannot autocomplete by Tab key, first check if your search path covers the package by env | grep ROS. If it already exist in the path, try rospack profile or reboot your system.
2. If prompt process has died, exit code -11, you may access data in the code which was not initialized.
3. If prompt The following roslaunch remote processes failed to register: * xxxx (timeout 10.0s), your network may have a problem, including hosts file, ROS_MASTER_URI, env loader, etc. (e.g. the hostname of your laptop was not exactly the same as you set in /etc/hosts file)
4. Launch sequence problem: service servers need to start earlier than clients. (C++ only, python solved this problem by wait_for_service function)
5. If prompt cannot launch node of type [some python file], you need to add execute permission to that python file.
6. Getting input and printing output in the same command line window will result in a kind of shifting of output lines.
7. If prompt Unable to establish ssh connection to [user@robot:22]: Server u'robot' not found in known_hosts, make sure you do ssh connection to your robot via RSA key. Then just remove the ~/.ssh/known_hosts file and ssh again to your robot.
8. If Gazebo crashed with segmentation fault right after waitForService: Service [/gazebo/set_physics_properties] has not been advertised, waiting... , turn off 3D Accleration in VirtualBox display settings.