README.md

Gazebo Simulation

This directory contains the code for simulating the Viper quadcopter in Gazebo Fortress. This version was selected as development was on an Ubuntu 22.04 machine.

If you wish to launch the model directly from command line without ROS 2 bridge, then cd into gazebo directory and run:

ign gazebo worlds/world.sdf

This will run with the sdf files you see in the gazebo dev directory. If simulation launched with viper-sim.py, it's actually running from the install/viper/share directory. Make sure to colcon build to copy it over.

Then in another terminal, run the following to make drone fly:

ign topic -t /X3/gazebo/command/motor_speed --msgtype ignition.msgs.Actuators -p 'velocity:[700, 700, 700, 700]'

Flight controller has a safety check for enable button, so above command will not work directly when flight controller running. Without the enable button held down, the flight controller sends a [0, 0, 0, 0] motor speed command immediately. If want to try out, launch this world by itself without flight controller code running. Will lose joystick support though.

Reset pose:

ign service -s /world/quadcopter_teleop/set_pose \
    --reqtype ignition.msgs.Pose \
    --reptype ignition.msgs.Boolean \
    --req "name: 'viper', position: {x: 0, y: 0, z: 3}, orientation: {x: 0, y: 0, z: 0, w: 1}" \
    --timeout 2000

PID Tuning

Within the model.sdf file, at the very bottom, we can change the joint type to lock the quadopter along certain axis or in certain positions in space, allowing for easier PID tuning. Use the ball joint for rotation about all three axes, and the roll joint for tuning along a certain axis.

Directory Structure

gazebo
├── config
│   └── bridge.yaml  # Config options for ros_gz_bridge
├── env-hooks
│   └── viper.dsv.in  # Defines the IGN_GAZEBO_RESOURCE_PATH
├── models
│   └── viper
│       ├── model.config  # Needed for loading model file correctly using the models/viper directory
│       └── model.sdf
├── README.md
└── worlds
    └── world.sdf

IGN_GAZEBO_RESOURCE_PATH currently points to gazebo directory. This allows launching of Gazebo simulation independently by just calling ign gazebo worlds/world.sdf from gazebo directory.

See original quadcopter example here.