/rt2_assignment1

Primary LanguageCMake

Research Track 2 - first assignment

OverView

the robot movement

  • the robot moves to the random position when user demand the robot to move.
    • when the user type 1 in the shell, the robot starts to move
    • when the user type 0 in the shell, the robot try to stop (in the action branch, the robot stops immediately. Otherwise, the robot can be stopped only when it reaches a target)

nodes

There are four main nodes

  • GotoPoint node
    • drive the robot towards the random position in space (x,y) and with a certain angle (theta)
  • User interface node
    • receive the user request
    • ask the state_machine to send the command to the robot
  • Position server node
    • reply with random values for x, y, and theta, where x and y should be limited between some min and max values
  • State machine node
    • give the possibility to start or stop the robot behaviour when the user requests

Requirements of assignment

Q1) Action branch

  • state machine node should now implement mechanisms for possibly canceling the goal, when user type stop (0) command in the shell

Q2) ROS2 branch

  • cpp nodes are written for ROS as components
  • by using the ros1_bridge, they can be interfaces with the ROS nodes and with simulation in Gazebo.

Q3) Main branch

  • use Vrep in stead of Gazebo

  • Vrep communicate with ROS (not ROS2)

Description of the content of the package

  • go_to_point.py
    • receive the goal position (/go_to_point)
    • control the velocity depending on the position
    • send the velocity (/cmd_vel)
  • user_interface.py
    • user interface (command line)
    • when the user put "start", the robot starts to move
    • when the user put "stop", the robot stops
  • position_service.cpp
    • when service is received from state machine, it returns the random position
  • state_machine.cpp
    • when service is recived from user interface, it sends the service to position_service.
    • it sends the random position as the goal to go_to_point

Topic

  • /cmd_vel
    • Type: gemetry_msgs/Twist
    • Publisher Node: /go_to_point
    • Subscriber Node: /gazebo or /vrep
  • /odom
    • Type: nav_msgs/Odometry
    • Publisher Node: /gazebo or /vrep
    • Subscriber Node: /go_to_point

Service

  • /go_to_point
    • Client Node: go_to_point
    • Server Node: state_machine
    • Type : Position
  • /position_server
    • Client Node: state_machine
    • Server Node: random_position_server
    • Type: RandomPosition
  • /user_interface
    • Client Node: user_interface
    • Server Node: state_machine
    • Type : Command

custom service

  • rt2_assignment1/RandomPosition

    • request

  • float32 x_max

    • float32 x_min
    • float32 y_max
    • float32 y_min
    • response
    • float32 x
      • float32 y
      • float32 theta

  • rt2_assignment1/Position

  • request

    • float32 x
    • float32 y
    • float32 theta
    • response
      • bool ok

  • rt2_assignment1/Position

    • request
      • string command
    • response
      • bool ok

Q2

Dependencies

his software is built on the Robotic Operating System ([ROS]), which needs to be install first and create the workspace.

  • Ubuntu 20.04
  • ROS noetic
  • gazebo

Compiling and Running

Build catkin_workspace

cd cakin_workspace
catkin_make

launch go_to_point.py and user_interface.py with gazebo

roslaunch rt2_assignment1 sim_python.launch

Q 3

Dependencies

This software is built on the Robotic Operating System ([ROS]), which needs to be install first and create the workspace.

  • Ubuntu 20.04
  • ROS noetic
  • CoppeliaSim V 4.2.0

Setting of CoppeliaSim

download

URI

http://www.coppeliarobotics.com/downloads.html

ROS integration

Vrep should be already6 integrated with ROS. You just need to launch the ROS master before running the V-REP (CoppeliaSim) software.

If there is any problem in building the plugin, you will need to recompile it by yourself: you can download it from here

# install xsltproc
Run apt-get install xsltproc

# install xmlschema
pip3 install xmlschema

git clone https://github.com/CoppeliaRobotics/simExtROS.git

In order to build the packages, navigate to the catkin_ws folder and type:

export COPPELIASIM_ROOT_DIR=~/path/to/coppeliaSim/folder
catkin_make --cmake-args -DCMAKE_BUILD_TYPE=Release

Vrep should be executed when the ROS master is already running

roscore

cd /install folder of Coppeliasim
./coppeliasim.sh

Copy the devel/lib/libsimExtROS.so file to the CoppeliaSim installation folder.

Compiling and Running

Build catkin_workspace

cd cakin_workspace
catkin_make

launch all the nodes without gazebo simulator

roslaunch rt2_assignment1 sim_vrep.launch

start CoppeliaSim

cd /install folder of Coppeliasim
./coppeliasim.sh

file->open scene->go to the vrep folder of rt2_assignment package-> pioneerROS_rt2.ttt

and run the simulator