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Note: This tutorial assumes that you have completed the previous tutorials: Chatter Concert.
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Turtle Concert

Description: An example concert demonstration, turtlesim style.

Keywords: concert

Tutorial Level: BEGINNER

Installation

Follow the rocon installation instructions.

Demo

Bootstrapping

Let's bootstrap all the robots as well as the centralised concert master. Source your setup.bash and rocon_launch the concert, e.g. for a source install:

> cd ~/concert/devel
> source setup.bash
> rocon_launch turtle_concert turtle.concert

rocon_launch is a utility used to multi-launch and manage several launchers running under independant ros masters. It has the same effect as running the following in four new setup.bash'd terminals:

# The concert master
> roslaunch --port=11311 turtle_concert concert.launch
# Two pseudo-turtle concert clients
> roslaunch --port=11312 turtle_concert kobuki.launch
> roslaunch --port=11313 turtle_concert guimul.launch
# A pc software client
> roslaunch --port=11314 turtle_concert turtlesim.launch

At this point, the concert master recognises all the concert clients have been loaded (it is pre-configured via the orchestra node) and is ready to run, but first, let's look around.

Looking Around

The concert system is essentially a centralised workspace. You can find all the topics and services landing there, allowing you to introspect and interact with the concert without having to delve into each robot (concert client). A quick look at the concert workspace (selectively filtering a bit here):

> rosservice list
/concert/conductor/invite_concert_clients
/concert/gateway/advertise
/concert/gateway/advertise_all
/concert/gateway/connect_hub
/concert/gateway/flip
/concert/gateway/flip_all
/concert/gateway/gateway_info
/concert/gateway/pull
/concert/gateway/pull_all
/concert/gateway/remote_gateway_info
/concert/start_solution
/concert/stop_solution
/concert/zeroconf/add_listener
/concert/zeroconf/add_service
/concert/zeroconf/list_discovered_services
/concert/zeroconf/list_published_services
/concert/zeroconf/remove_listener
/concert/zeroconf/remove_service
/guimul/invitation                                                                                  
/guimul/list_apps                                                                                   
/guimul/platform_info                                                                               
/guimul/start_app                                                                                   
/guimul/status                                                                                      
/guimul/stop_app                                                                                    
/kobuki/invitation
/kobuki/list_apps
/kobuki/platform_info
/kobuki/start_app
/kobuki/status
/kobuki/stop_app
/turtlesim/invitation
/turtlesim/list_apps
/turtlesim/platform_info
/turtlesim/start_app
/turtlesim/status
/turtlesim/stop_app

Starting the Solution

The orchestration component of the concert master is pre-loaded with a solution. Think of this as a multimaster launch file which launches apps (launchers) on each robot instead of nodes.

From the concert workspace (ROS_MASTER_URI=http://localhost:11311)

> rosservice call /concert/start_solution

Viewing the Gateway Graph

Have a gander and see what topics and services are getting the love (i.e. shared around):

> rosrun rocon_gateway_graph rqt_gateway_graph

Wrapping Up

Put the turtles to sleep. Again, from the concert workspace (ROS_MASTER_URI=http://localhost:11311)

> rosservice call /concert/stop_solution

Screenshot

Turtle Concert


2019-12-07 13:13