Simulating Syskit Systems with Gazebo

• File Organization
• First step: running Gazebo and linking it to Syskit
• Caveats

Gazebo is fully integrated in Rock&Syskit systems to support system development. Syskit's support for Gazebo includes:

• control and status of any links
• control and status of any joints
• interface with Gazebo sensors
• support for recursive models
• using SDF as a representation of a system's kinematic configuration (i.e. as a source of configuration for the transformer). This support is also usable in live systems, without Gazebo, allowing to use the SDF representation as a common source of truth

This documentation chapter will cover first the link between the SDF model kinematics (links and joints) and Syskit, that is how to control and/or get information about a system that is running in Gazebo. We will then talk about extending gazebo with plugins, and adding support for them at the boundary with Rock and Syskit. We will then finally talk about the relationship between the SDF models in your simulation and the transformer - that is, Rock's system to handle geometric transformations system-wide

File Organization

By convention, a Gazebo world named foobar is saved within the scenes/foobar/foobar.world file in the bundles. SDF models are saved in the models/sdf/ subfolder of the bundles.

First step: running Gazebo and linking it to Syskit

The Gazebo-based workflow within Syskit assumes that gazebo is started externally. This is to avoid "resetting" the world when Syskit itself is restarted, a workflow that gets closer to the "real" development process.

To have gazebo and Syskit together, you have to:

• run your world using the rock-gazebo tool (instead of gzserver / gazebo). Apart from injecting our plugin, the tool also takes care of some preprocessing necessary to run oroGen task contexts within the gazebo context.

• add the following snippet at the beginning of your robot config's init block:

  require "rock_gazebo/syskit
  

• add the following snippet at the beginning of your robot config's requires block:

  Syskit.conf.use_gazebo_world(world_name)
  

  where world_name is the name of the world without the .world

Because rock-gazebo performs preprocessing, one may want to inspect the generated world. This can be done with --parse-sdf-only

The world name passed to use_gazebo_world ends up being your "default world", i.e. should be the world you use most of the time. If you want to switch to a different world, you may pass --set sdf.world_name=another_world to syskit ide or syskit run

Caveats

The vizkit3d visualization does not support 100% of the same formats that Gazebo supports. For instance, the collada (.dae) format is not supported by gazebo itself. If you choose a 3D model that is not supported by both, either one or the other won't be able to visualize the model properly.