ROS Control x Jetracer

Installation

Setup for the Waveshare Jetracer

Bill of Materials

Part	Description
Waveshare Jetracer AI Kit	Autonomous Car with a Jetson Nano 4GB (Description on Waveshare Webpage)
Arduino Uno	Microcontroller board based on the ATmega328P
12V DC Encoder Motor	Replaces the standard DC Motors in the back of the Jetracer (Description on the Robotshop Website)
Base Plate	Replaces the standard aluminium base plate of the Jetracer to make room for the encoder motors (.stl file found in /construction folder)
Gearmotor Bracket	Needed to mount the new motors to the new base plate
RPLIDAR A1M8	360° Laser Scanner Description on Slamtec Website
M2.5 & M3 Hex Spacer and Bolts	To mount the LIDAR on top of the Jetson

Hardware Wiring

To wire up the Arduino to the Rear Motors correctly the 6 Pins have to be connected correctly.

Encoder Pinout


Connections to Arduino


Software Setup

1. Follow the steps laid out in the Waveshare Jetracer Wiki

2. Install ROS Melodic Full on both the Jetson and your Workstation as described on the ROS.org Website

3. Create a new catkin workspace with:

   mkdir catkin_ws
   cd catkin_ws 
   mkdir src
   

4. Clone this repo into the src folder

   cd src
   git clone https://gitlab.rz.htw-berlin.de/s0570976/ros-control-x-jetracer.git
   git submodule init
   git submodule update
   cd ros_control_boilerplate
   git fetch
   git checkout melodic-devel
   cd ~/catkin_ws
   

5. Install all needed dependencies with rosdep

   sudo apt-get install python-rosdep
   sudo rosdep init
   rosdep update
   rosdep install --from-paths src --ignore-src -r -y
   

6. Install all needed ROS functionalities on the workstation (ROS master)

   sudo apt-get install ros-melodic-navigation
   sudo apt-get install ros-melodic-gmapping
   

7. Install all needed ROS functionalities on the Jetson

   sudo apt-get install ros-melodic-ackermann-steering-controller
   sudo apt-get install ros-melodic-ackermann-steering-msgs
   sudo apt-get install ros-melodic-rplidar-ros
   sudo apt-get install ros-melodic-joint-state-controller
   sudo apt-get install ros-melodic-robot-state-publisher 
   

8. Build the workspace and source (Workspace and Jetson)

   cd ~/catkin_ws
   catkin_make
   source devel/setup.bash
   

9. To make the nodes visible in the ROS network the IP adress of the host device has to be added to the environment variables. This is best done via an export statement in the terminal. To find the IP adress "ifconfig" Adding the statement to the .bashrc both on the Host and Client makes sense, e.g.

   For the host:

   export ROS_MASTER_URI=http://192.168.178.53:11311
   export ROS_HOSTNAME=192.168.178.53
   

   For the client:

   export ROS_MASTER_URI=http://192.168.178.53:11311
   export ROS_HOSTNAME=192.168.178.31
   

Usage

Jetson

• Launch the required nodes and parameters (each in a new and sourced terminal) with:

  roslaunch fennec_bringup fennec_bringup.launch
  rosrun rosserial_python serial_node.py  _port:=/dev/ttyACM0 _baud:=115200
  

Workstation

• Launch the required nodes and parameters (each in a new and sourced terminal) with:

  roscore
  roslaunch fennec_bringup laptop_bringup.launch
  

• You can then see the robot representation and the generated map in Rviz and send navigation goals to let the robot drive there