Gazebo topic subscribe

Gazebo communicates on TCP/IP sockets Messages are sent on named channels called topics via publishers. On the other side of a topic are subscribers, which receive callbacks when messages arrive.

gz topic -l list the topic on running system

Subscriber

Demo code subscribe to /gazebo/default/world_stats

• topic list

gz topic -l

....
/gazebo/default/world_control

/gazebo/default/world_stats

/gazebo/motor_failure_num
/gazebo/server/control
/gazebo/world/modify

• topic info

gz topic -i /gazebo/default/world_stats
Type: gazebo.msgs.WorldStatistics

Publishers:
 192.168.2.200:39165

Subscribers:

• topic message view

# gz topic -e (echo)
gz topic -v /gazebo/default/world_stats

Write code

• Reference

• My GIT

• cmake file (not include project name and minimum_required)

find_package(gazebo REQUIRED)

include_directories(${GAZEBO_INCLUDE_DIRS})
link_directories(${GAZEBO_LIBRARY_DIRS})
list(APPEND CMAKE_CXX_FLAGS "${GAZEBO_CXX_FLAGS}")

add_executable(sub_demo sub_demo.cpp)
target_link_libraries(sub_demo ${GAZEBO_LIBRARIES} pthread)

• sub_demo source

#include <gazebo-7/gazebo/transport/TransportIface.hh>
#include <gazebo-7/gazebo/msgs/msgs.hh>
#include <gazebo-7/gazebo/gazebo_client.hh>

#include <iostream>
#include <csignal>

const std::string TOPIC = "/gazebo/default/world_stats";

void my_shutdown(int signal){
    std::cout<<"shutdown gazebo client" << std::endl;
    gazebo::client::shutdown();
    exit(0);
}

void cb(ConstWorldStatisticsPtr &_msg){
    std::cout << _msg->DebugString() << std::endl;
}

int main(int argc, char **argv){
    signal (SIGINT, my_shutdown);
    gazebo::client::setup(argc, argv);

    //create node for communication
    gazebo::transport::NodePtr node(new gazebo::transport::Node());
    node->Init();

    //subscribe to topic
    gazebo::transport::SubscriberPtr sub = node->Subscribe(TOPIC, cb);

    while(true){
        gazebo::common::Time::MSleep(100);
    }
    
    return 0;
}