tractor_sim

Package for simulating the Autonomous Tractor. For further project information, see the GRAVL main repository wiki: (link)

Setup

Dependencies:

• GRAVL - for teleop and testing code
• Follow setup instructions on the GRAVL wiki if you haven't already (reference)
• tractor_sim_packages - packages for simulated localization and odometry
• velodyne_simulator - packages for simulated 3D lidar

Installation:

cd ~/catkin_ws/src
git clone https://github.com/SNU-SF4/tractor_sim
git clone https://github.com/SNU-SF4/gravl.git
git clone https://github.com/SNU-SF4/state_controller.git

# install essential packages
rosdep install --from-paths src --ignore-src -r -y --os=ubuntu:focal
sudo apt install ros-noetic-ackermann-msgs ros-noetic-mavros-msgs ros-noetic-gps-common

# install velodyne related packages
sudo apt install ros-noetic-velodyne-description ros-noetic-velodyne-gazebo-plugins ros-noetic-velodyne-simulator

cd ~/catkin_ws/
catkin build

To use the models included in this repo, copy the contents of the folder to ~/.gazebo/models

cd ~/catkin_ws/src/tractor_sim/tractor_sim_gazebo/models
cp -R . ~/.gazebo/models

Usage

To run simulation:

• roslaunch tractor_sim_gazebo bringup.launch

ROS Topics

• /cmd_vel - twist command for driving the tractor
• /cmd_hitch - pose command for setting height of box blade (reference)

Sensor Topics

• /camera/image_raw - camera feed
• /gps/fix - rtk gps data
• /imu/data - imu data
• /scan - downward facing LiDar data

Other Topics

• /odometry/filtered - tractor odometry
• /laser_pointcloud - generated pointcloud

Troubleshooting

If using the main launch file doesn't work for you, you can just run individual launch files to suit your needs To run simulation without external dependencies:

• roslaunch tractor_sim_gazebo bringup_min.launch

To run rviz:

• roslaunch tractor_sim_description tractor_sim_rviz.launch

To test code:

• rosrun gravl yourscript.py (ex: rosrun gravl LidarFollower.py)

To run simulation (without teleop, hitch controls, localization, or any extra code running)

• roslaunch tractor_sim_gazebo tractor_sim.launch

To run teleop (following https://github.com/olinrobotics/gravl/wiki/Kubo:-Overview):

• roslaunch gravl teleop.launch
• roslaunch gravl mainstate.launch

To setup localization:

• roslaunch gravl localization.launch

To setup hitch commands:

• roslaunch tractor_sim_gazebo hitch.launch

Parameters

• tractor_delay - either 0 or 1. If set to 1, then tractor will react instantaneously to commands. If set to 1, the tractor will simulate the delayed response time of the real tractor (Default: 1)
• max_acceleration - maximum acceleration for the tractor Note: only works when tractor_delay is 0 (Default: 0.4)
• max_steering_angle_velocity - maximum steering velocity Note: only works when tractor_delay is set to 0 (Default: 1)

Known Issues

• Running the launch file will throw the warning

[WARN] [1590601461.920958, 0.000000]: Controller Spawner couldn't find the expected controller_manager ROS interface.

if the controller spawner loads before gazebo loads, which is likely. To get around this, in the launch file the controller spawner's node has respawn="true". Ideally, this should wait for gazebo to finish loading before starting the node so that the warning doesn't pop up, but this works for now.