prsg2_robot

ROS launch files and configuration for the PRSG rev 2 robot.

Configuration for Your Robot

IR Sensor Frames and Locations

The YAML parameters in launch/prsg2_controller.launch and the URDF file in urdf/prsg2_description.xacro both define and use frame names for the IR sensors and the sensor locations. You will need to modify both of these files depending on how many sensors you have installed.

Wheel Size and Separation

Some of us are using 60mm wheels and some 70mm. In addition, the wheel separation may vary a little depending on the chassis. You will need to edit the YAML parameters in the launch file. Both of these values are in meters.

For the robot using Darron’s chassis:

wheel_diameter: 0.070
wheel_track: 0.200

The wheel_track value for the wheel separation may vary a little, so measure it on your robot. I’ve found it’s best to measure from the centers of the tires, rather than the inside or outside edges.

ros_arduino_bridge Communication Style

Some of us are using the Arduino UART and some are using the built-in I2C communication between the A-Star and the RPi. These parameters will need to change if you use I2C:

For UART communication:

port: /dev/ttyAMA0
baud: 115200

For I2C communication:

port: 1
baud: 57600

Packages you may need

On the robot host machine:

sudo apt-get install liburdfdom-tools.
sudo apt-get install ros-indigo-urdf
sudo apt-get install ros-indigo-xacro
sudo apt-get install ros-indigo-robot-state-publisher
sudo apt-get install ros-indigo-joint-state-publisher

On RVIZ machine, you may need to install the packages listed just prior. You will also need:

sudo apt-get install ros-indigo-effort-controllers
sudo apt-get install ros-indigo-rviz

Building and Installing the Files

You must run catkin_make once in order to install the package files into the proper places.

cd ~/catkin_ws
catkin_make

Using the Launch Files

One way to launch the robot controller for teleop is to run the prsg2_controller.launch file like this:

roslaunch prsg2_robot prsg2_controller.launch

This sets up ros_arduino_bridge and publishes the frame transformations from the URDF. Any teleop node should be able to send /cmd_vel messages to drive the robot. In addition, all the IR sensors will publish Range messages.

One possible teleop node is the virtual_joystick.py node in the differential_drive package.

Or, if you want to send movement commands by-hand, the following command causes the robot to drive in a circle to the right.

rostopic pub -r 10 /cmd_vel geometry_msgs/Twist '{linear: {x: 0.2}, angular: {z: -0.1}}'