Added frame_id parameter to lidar sensor

Signed-off-by: ahcorde <ahcorde@gmail.com>

src/Lidar.cc

@@ -45,6 +45,9 @@ class ignition::sensors::LidarPrivate
 
   /// \brief Sdf sensor.
   public: sdf::Lidar sdfLidar;
+
+  /// \brief frame id
+  public: std::string frame_id;
 };
 
 //////////////////////////////////////////////////
@@ -166,6 +169,17 @@ bool Lidar::Load(const sdf::Sensor &_sdf)
     }
   }
 
+  sdf::ElementPtr element = _sdf.Element();
+  // Get the background color, if specified.
+  if (element->HasElement("frame_id"))
+  {
+    this->dataPtr->frame_id = element->Get<std::string>("frame_id");
+  }
+  else
+  {
+    this->dataPtr->frame_id = this->Name();
+  }
+
   this->initialized = true;
   return true;
 }
@@ -232,7 +246,7 @@ bool Lidar::PublishLidarScan(const ignition::common::Time &_now)
   auto frame = this->dataPtr->laserMsg.mutable_header()->add_data();
   frame->set_key("frame_id");
   frame->add_value(this->Name());
-  this->dataPtr->laserMsg.set_frame(this->Name());
+  this->dataPtr->laserMsg.set_frame(this->dataPtr->frame_id);
 
   // Store the latest laser scans into laserMsg
   msgs::Set(this->dataPtr->laserMsg.mutable_world_pose(),