Hello there,

I created a light sensor plugin with the topic called : /lightsensorplugin/light. When I launch one robot I do not find any issue. However, as this is a constant topic name, when launching several robots in their respective tags, there is only one topic for the light sensor for all of them. This leads to make all of them to publish in that topic.

How can I change the topic name in my plugin so that it takes the prefix/name of each robot creating a different light sensor topic for each robot?

Here is my code: PLUGINS:

HEADER: enter code here

#ifndef GAZEBO_ROS_LIGHT_SENSOR_HH
#define GAZEBO_ROS_LIGHT_SENSOR_HH

#include <string>
#include <iostream>
#include <stdio.h>
// library for processing camera data for gazebo / ros conversions
#include <gazebo/plugins/CameraPlugin.hh>

#include <gazebo_plugins/gazebo_ros_camera_utils.h>

namespace gazebo
{
  class GazeboRosLight : public CameraPlugin, GazeboRosCameraUtils
  {
    /// \brief Constructor
    /// \param parent The parent entity, must be a Model or a Sensor
    public: GazeboRosLight();

    /// \brief Destructor
    public: ~GazeboRosLight();


    /// \brief Load the plugin
    /// \param take in SDF root element
    public: void Load(sensors::SensorPtr _parent, sdf::ElementPtr _sdf);

    /// \brief Update the controller
    protected: virtual void OnNewFrame(const unsigned char *_image,
    unsigned int _width, unsigned int _height,
    unsigned int _depth, const std::string &_format);

    ros::NodeHandle _nh;
    ros::Publisher _sensorPublisher;

    double _fov;
    double _range;
  };
}
#endif

MAIN enter code here

#include <gazebo/common/Plugin.hh>
#include <ros/ros.h>
#include <gazebo_light_sensor_plugin/light_sensor_plugin.h>

#include <gazebo_plugins/gazebo_ros_camera.h>

#include <string>
#include <iostream>
#include <stdio.h>
#include <gazebo/sensors/Sensor.hh>
#include <gazebo/sensors/CameraSensor.hh>
#include <gazebo/sensors/SensorTypes.hh>

#include <sensor_msgs/Illuminance.h>

namespace gazebo
{
  // Register this plugin with the simulator
  GZ_REGISTER_SENSOR_PLUGIN(GazeboRosLight)


  ////////////////////////////////////////////////////////////////////////////////
  // Constructor
  GazeboRosLight::GazeboRosLight():
  _nh("light_sensor_plugin"),
  _fov(6),
  _range(10)
  {

    _sensorPublisher = _nh.advertise<sensor_msgs::Illuminance>("light", 1);
  }

  ////////////////////////////////////////////////////////////////////////////////
  // Destructor
  GazeboRosLight::~GazeboRosLight()
  {
    ROS_DEBUG_STREAM_NAMED("camera","Unloaded");
  }

  void GazeboRosLight::Load(sensors::SensorPtr _parent, sdf::ElementPtr _sdf)
  {
    // Make sure the ROS node for Gazebo has already been initialized
    if (!ros::isInitialized())
    {
      ROS_FATAL_STREAM("A ROS node for Gazebo has not been initialized, unable to load plugin. "
        << "Load the Gazebo system plugin 'libgazebo_ros_api_plugin.so' in the gazebo_ros package)");
      return;
    }

    CameraPlugin::Load(_parent, _sdf);
    // copying from CameraPlugin into GazeboRosCameraUtils
    this->parentSensor_ = this->parentSensor;
    this->width_ = this->width;
    this->height_ = this->height;
    this->depth_ = this->depth;
    this->format_ = this->format;
    this->camera_ = this->camera;

    GazeboRosCameraUtils::Load(_parent, _sdf);

  }

  ////////////////////////////////////////////////////////////////////////////////

  // Update the controller
  void GazeboRosLight::OnNewFrame(const unsigned char *_image,
    unsigned int _width, unsigned int _height, unsigned int _depth,
    const std::string &_format)
  {
    static int seq=0;

    this->sensor_update_time_ = this->parentSensor_->LastUpdateTime();

    if (!this->parentSensor->IsActive())
    {
      if ((*this->image_connect_count_) > 0)
      // do this first so there's chance for sensor to run once after activated
        this->parentSensor->SetActive(true);
    }
    else
    {
      if ((*this->image_connect_count_) > 0)
      {
        common::Time cur_time = this->world_->SimTime();
        if (cur_time - this->last_update_time_ >= this->update_period_)
        {
          this->PutCameraData(_image);
          this->PublishCameraInfo();
          this->last_update_time_ = cur_time;

          sensor_msgs::Illuminance msg;
          msg.header.stamp = ros::Time::now();
          msg.header.frame_id = "";
          msg.header.seq = seq;

          int startingPix = _width * ( (int)(_height/2) - (int)( _fov/2)) - (int)(_fov/2);

          double illum = 0;
          for (int i=0; i<_fov ; ++i)
          {
            int index = startingPix + i*_width;
            for (int j=0; j<_fov ; ++j)
              illum += _image[index+j];
          }

          msg.illuminance = illum/(_fov*_fov);
          msg.variance = 0.0;

          _sensorPublisher.publish(msg);

          seq++;
        }
      }
    }
  }
}

MYBOT.GAZEBO This is where I implement my plugin:

<gazebo reference="light_sensor">
<robotNamespace>/$(arg nsp)</robotNamespace>
     <sensor name='camera' type='camera'>
       <camera name='__default__'>
         <horizontal_fov>1.047</horizontal_fov>
         <image>
           <width>320</width>
           <height>240</height>
         </image>
         <clip>
           <near>0.1</near>
           <far>100</far>
         </clip>
       </camera>
       <plugin name="gazebo_light_sensor_plugin" filename="libgazebo_light_sensor_plugin.so">
         <cameraName>camera</cameraName>
         <alwaysOn>true</alwaysOn>
         <updateRate>10</updateRate>
         <imageTopicName>rgb/image_raw</imageTopicName>
         <depthImageTopicName>depth/image_raw</depthImageTopicName>
         <pointCloudTopicName>depth/points</pointCloudTopicName>
         <cameraInfoTopicName>rgb/camera_info</cameraInfoTopicName>
         <depthImageCameraInfoTopicName>depth/camera_info</depthImageCameraInfoTopicName>
         <frameName>camera_depth_optical_frame</frameName>
         <baseline>0.1</baseline>
         <distortion_k1>0.0</distortion_k1>
         <distortion_k2>0.0</distortion_k2>
         <distortion_k3>0.0</distortion_k3>
         <distortion_t1>0.0</distortion_t1>
         <distortion_t2>0.0</distortion_t2>
         <pointCloudCutoff>0.4</pointCloudCutoff>
       </plugin>
     </sensor>
  </gazebo>