ohm_mecanum_sim

This package comprises a pygame-based robot simulation for mecanum-driven kinematic concepts.

Tests have been performed with ROS melodic, albeit the used python versions differ. While ROS melodic uses python2.x, the simulator need python3. The reason is, that ROS noetic will require python3. In order to make the simulator work with ROS melodic, you can follow the installation hints below.

Prerequisites on Ubuntu 18.04

Installing python3 aside python2 can be done with pip:

user@machine:~$ sudo apt install python3 python-pip python3-pip python-catkin-tools
user@machine:~$ sudo update-alternatives --install /usr/bin/python python /usr/bin/python2.7 1
user@machine:~$ sudo update-alternatives --install /usr/bin/python python /usr/bin/python3.6 2
user@machine:~$ pip install -U defusedxml rospkg pygame pycryptodomex gnupg pyside2 pydot numpy

Starting the simulator

Go to your catkin workspace / execute the following commands (replace the path to your catkin workspace accordingly):

user@machine:~$ roscore &
user@machine:~$ cd workspace/catkin_ws
user@machine:~/workspace/catkin_ws$ catkin_make
user@machine:~/workspace/catkin_ws$ source devel/setup.bash
user@machine:~/workspace/catkin_ws$ python3 src/ohm_mecanum_sim/scripts/ohm_mecanum_sim_node.py

Moving around the robots

One can use different tools to make the robot move:

• Publish joy messages to a certain robot instance (if you have a joystick)

user@machine:~$ rosrun joy joy_node joy:=/robot1/joy

• Publish a twist message manually by using rostopic pub

user@machine:~$ rostopic pub -r 10 /robot1/cmd_vel geometry_msgs/Twist ...

• Use a keyboard tool, like teleop_twist_keyboard (install ros-melodic-teleop-twist-keyboard first)

user@machine:~$ rosrun teleop_twist_keyboard teleop_twist_keyboard.py cmd_vel:=/robot1/cmd_vel

• Publish wheel speed messages (individual angular velocity for each wheel)

user@machine:~$ rostopic pub -r 10 /robot1/wheel_speed ohm_mecanum_sim/WheelSpeed ...

• ... or write your own node.