1. MPI_Allgatherv, version 0.6.2

2. a little modification in MPI_Gazebo_launch.sh and mygzserver
3. reduce link::update in worldUpdateBegin
4. modify time computing method in world.cc

Gazebo_Distributed_MPI/gazebo/common/Event.hh

@@ -35,6 +35,9 @@
 #include <gazebo/math/Helpers.hh>
 #include "gazebo/util/system.hh"
 
+#include <iomanip> //Added by zhangshuai 2019.09.09
+#include <sys/time.h> //Added by zhangshuai 2019.09.09
+
 namespace gazebo
 {
   /// \ingroup gazebo_event
@@ -381,8 +384,26 @@ namespace gazebo
         this->myDataPtr->signaled = true;
         for (auto iter: this->myDataPtr->connections)
         {
+          //std::cout << iter.first << std::endl; //zhangshuai test 2019.09.10
+
+          //struct timespec ts;
+          //clock_gettime(CLOCK_REALTIME, &ts);
+          //long cur_time;
+          //long update_time;
+
+          //cur_time = (double)ts.tv_sec + (double)ts.tv_nsec / 1.e9;<< std::scientific
+      
+          //cur_time = ts.tv_nsec;
+
           if (iter.second->on)
             (*iter.second->callback)(_p);
+
+          //clock_gettime(CLOCK_REALTIME, &ts);
+          //update_time = ts.tv_nsec - cur_time;
+      
+          //std::cout << "===== time1 : " << cur_time << std::endl; //zhangshuai test 2019.09.10
+          //std::cout << "===== time2 : " << ts.tv_nsec << std::endl; //zhangshuai test 2019.09.10
+          //std::cout << "===== OnUpdate time : " << update_time << std::endl; //zhangshuai test 2019.09.10
         }
       }
 

Gazebo_Distributed_MPI/gazebo/physics/Link.cc

@@ -246,8 +246,32 @@ void Link::Load(sdf::ElementPtr _sdf)
     }
   }
 
-  this->connections.push_back(event::Events::ConnectWorldUpdateBegin(
+  //this->connections.push_back(event::Events::ConnectWorldUpdateBegin(
-      boost::bind(&Link::Update, this, _1)));
+  //    boost::bind(&Link::Update, this, _1)));
+
+  // Modified by zhangshuai 2019.09.10 ----Begin
+  if (this->GetWorld()->GetFlag() == 1)
+  {
+    // Judge if the model to load is simulated in this gazebo
+    for (unsigned int i = 0; i < this->GetWorld()->GetDistribution()->GetGazeboIDPtr(this->GetWorld()->GetGazeboLocalID())->GetModelCount(); i++)
+    {
+      if (this->GetModel()->GetName() == this->GetWorld()->GetDistribution()->GetGazeboIDPtr(this->GetWorld()->GetGazeboLocalID())->GetModelName(i))
+      {
+        // Original part
+        this->connections.push_back(event::Events::ConnectWorldUpdateBegin(
+            boost::bind(&Link::Update, this, _1)));
+        // Original part
+      }
+    }
+  }
+  else
+  {
+    // Original part
+    this->connections.push_back(event::Events::ConnectWorldUpdateBegin(
+        boost::bind(&Link::Update, this, _1)));
+    // Original part
+  }
+  // Modified by zhangshuai 2019.09.10 ----End
 
   std::string topicName = "~/" + this->GetScopedName() + "/wrench";
   boost::replace_all(topicName, "::", "/");

Gazebo_Distributed_MPI/gazebo/physics/World.cc

@@ -107,6 +107,21 @@ double before_mpiTime = 0;
 double mpiTime = 0;
 double after_mpiTime = 0;
 double wholeUpdataTime = 0;
+
+double before_worldUpdateBeginTime2 = 0;
+double worldUpdateBeginTime2 = 0;
+double modelUpdateFuncTime2 = 0;
+double updateCollisionTime2 = 0;
+double loggingTime2 = 0;
+double before_updatePhysicsTime2 = 0;
+double updatePhysicsTime2 = 0;
+double before_mpiTime2 = 0;
+double mpiTime2 = 0;
+double after_mpiTime2 = 0;
+double wholeUpdataTime2 = 0;
+double simtime = 0;
+double realtime = 0;
+uint64_t start_iterations = 0;
 #endif
 // Added by zhangshuai 2019.04.03 for count time ----End
 
@@ -271,7 +286,13 @@ void World::Load(sdf::ElementPtr _sdf)
   this->dataPtr->lightFactoryPub = this->dataPtr->node->Advertise<msgs::Light>(
       "~/factory/light");
 
-  // Added by zhangshuai based on zenglei 2019.04.23 ----Begin
+  // Added by zhangshuai based on zenglei 2019.09.23 ----Begin
+  std::cout << " ____________________________________________________________" << std::endl;
+  std::cout << "|              This is Gazebo-Exercise-MPI 0.6               |" << std::endl;
+  std::cout << "|                         by AIRC-01                         |" << std::endl;
+  std::cout << "|____________________________________________________________|" << std::endl;
+  // Added by zhangshuai based on zenglei 2019.04.23 ----End
+
   if (this->dataPtr->sdf->HasElement("distribution"))
   {
     sdf::ElementPtr distributionElem = this->dataPtr->sdf->GetElement("distribution");
@@ -1048,26 +1069,44 @@ void World::Update()
 
 #ifdef USE_COUNT_TIME
   // std::cout << "===== end iterations:\t" << this->dataPtr->iterations << std::endl;
+  if (this->dataPtr->iterations == 0)
+  {
+    before_worldUpdateBeginTime2 = before_worldUpdateBeginTime;
+    worldUpdateBeginTime2 = worldUpdateBeginTime;
+    modelUpdateFuncTime2 = modelUpdateFuncTime;
+    updateCollisionTime2 = updateCollisionTime;
+    loggingTime2 = loggingTime;
+    before_updatePhysicsTime2 = before_updatePhysicsTime;
+    updatePhysicsTime2 = updatePhysicsTime;
+    before_mpiTime2 = before_mpiTime;
+    mpiTime2 = mpiTime;
+    after_mpiTime2 = after_mpiTime;
+    wholeUpdataTime2 = wholeUpdataTime;
+    simtime = this->GetSimTime().Double();
+    realtime = this->GetRealTime().Double();
+    start_iterations = this->dataPtr->iterations;
+  }
+
   if (this->dataPtr->iterations == 100000)
   {
     // if (this->gazeboLocalID == 0)
     // {
-    std::cout << "===== average before_worldUpdateBeginTime:\t" << before_worldUpdateBeginTime * 1000.0 / this->dataPtr->iterations << "\tms =====\t" << this->gazeboLocalID << std::endl;
+    std::cout << "===== average before_worldUpdateBeginTime:\t" << (before_worldUpdateBeginTime - before_worldUpdateBeginTime2) * 1000.0 / (this->dataPtr->iterations - start_iterations) << "\tms =====\t" << this->gazeboLocalID << std::endl;
-    std::cout << "===== average worldUpdateBeginTime:\t" << worldUpdateBeginTime * 1000.0 / this->dataPtr->iterations << "\tms =====\t" << this->gazeboLocalID << std::endl;
+    std::cout << "===== average worldUpdateBeginTime:\t" << (worldUpdateBeginTime - worldUpdateBeginTime2) * 1000.0 / (this->dataPtr->iterations - start_iterations) << "\tms =====\t" << this->gazeboLocalID << std::endl;
-    std::cout << "===== average modelUpdateFuncTime:\t" << modelUpdateFuncTime * 1000.0 / this->dataPtr->iterations << "\tms =====\t" << this->gazeboLocalID << std::endl;
+    std::cout << "===== average modelUpdateFuncTime:\t" << (modelUpdateFuncTime - modelUpdateFuncTime2) * 1000.0 / (this->dataPtr->iterations - start_iterations) << "\tms =====\t" << this->gazeboLocalID << std::endl;
-    std::cout << "===== average updateCollisionTime:\t" << updateCollisionTime * 1000.0 / this->dataPtr->iterations << "\tms =====\t" << this->gazeboLocalID << std::endl;
+    std::cout << "===== average updateCollisionTime:\t" << (updateCollisionTime - updateCollisionTime2) * 1000.0 / (this->dataPtr->iterations - start_iterations) << "\tms =====\t" << this->gazeboLocalID << std::endl;
-    std::cout << "===== average loggingTime:\t" << loggingTime * 1000.0 / this->dataPtr->iterations << "\tms =====\t" << this->gazeboLocalID << std::endl;
+    std::cout << "===== average loggingTime:\t" << (loggingTime - loggingTime2) * 1000.0 / (this->dataPtr->iterations - start_iterations) << "\tms =====\t" << this->gazeboLocalID << std::endl;
-    std::cout << "===== average before_updatePhysicsTime:\t" << before_updatePhysicsTime * 1000.0 / this->dataPtr->iterations << "\tms =====\t" << this->gazeboLocalID << std::endl;
+    std::cout << "===== average before_updatePhysicsTime:\t" << (before_updatePhysicsTime - before_updatePhysicsTime2) * 1000.0 / (this->dataPtr->iterations - start_iterations) << "\tms =====\t" << this->gazeboLocalID << std::endl;
-    std::cout << "===== average updatePhysicsTime:\t" << updatePhysicsTime * 1000.0 / this->dataPtr->iterations << "\tms =====\t" << this->gazeboLocalID << std::endl;
+    std::cout << "===== average updatePhysicsTime:\t" << (updatePhysicsTime - updatePhysicsTime2) * 1000.0 / (this->dataPtr->iterations - start_iterations) << "\tms =====\t" << this->gazeboLocalID << std::endl;
-    std::cout << "===== average before_mpiTime:\t" << before_mpiTime * 1000.0 / this->dataPtr->iterations << "\tms =====\t" << this->gazeboLocalID << std::endl;
+    std::cout << "===== average before_mpiTime:\t" << (before_mpiTime - before_mpiTime2) * 1000.0 / (this->dataPtr->iterations - start_iterations) << "\tms =====\t" << this->gazeboLocalID << std::endl;
-    std::cout << "===== average mpiTime:\t" << mpiTime * 1000.0 / this->dataPtr->iterations << "\tms =====\t" << this->gazeboLocalID << std::endl;
+    std::cout << "===== average mpiTime:\t" << (mpiTime - mpiTime2) * 1000.0 / (this->dataPtr->iterations - start_iterations) << "\tms =====\t" << this->gazeboLocalID << std::endl;
-    std::cout << "===== average after_mpiTime:\t" << after_mpiTime * 1000.0 / this->dataPtr->iterations << "\tms =====\t" << this->gazeboLocalID << std::endl;
+    std::cout << "===== average after_mpiTime:\t" << (after_mpiTime - after_mpiTime2) * 1000.0 / (this->dataPtr->iterations - start_iterations) << "\tms =====\t" << this->gazeboLocalID << std::endl;
-    double wholeMpiTime = before_mpiTime + mpiTime + after_mpiTime;
+    double wholeMpiTime = before_mpiTime + mpiTime + after_mpiTime - (before_mpiTime2 + mpiTime2 + after_mpiTime2);
-    std::cout << "===== average wholeMpiTime:\t" << wholeMpiTime * 1000.0 / this->dataPtr->iterations << "\tms =====\t" << this->gazeboLocalID << std::endl;
+    std::cout << "===== average wholeMpiTime:\t" << wholeMpiTime * 1000.0 / (this->dataPtr->iterations - start_iterations) << "\tms =====\t" << this->gazeboLocalID << std::endl;
-    double wholeAddTime = before_worldUpdateBeginTime + worldUpdateBeginTime + modelUpdateFuncTime + updateCollisionTime + loggingTime + before_updatePhysicsTime + updatePhysicsTime + before_mpiTime + mpiTime + after_mpiTime;
+    double wholeAddTime = before_worldUpdateBeginTime + worldUpdateBeginTime + modelUpdateFuncTime + updateCollisionTime + loggingTime + before_updatePhysicsTime + updatePhysicsTime + before_mpiTime + mpiTime + after_mpiTime - (before_worldUpdateBeginTime2 + worldUpdateBeginTime2 + modelUpdateFuncTime2 + updateCollisionTime2 + loggingTime2 + before_updatePhysicsTime2 + updatePhysicsTime2 + before_mpiTime2 + mpiTime2 + after_mpiTime2);
-    std::cout << "===== average wholeAddTime:\t" << wholeAddTime * 1000.0 / this->dataPtr->iterations << "\tms =====\t" << this->gazeboLocalID << std::endl;
+    std::cout << "===== average wholeAddTime:\t" << wholeAddTime * 1000.0 / (this->dataPtr->iterations - start_iterations) << "\tms =====\t" << this->gazeboLocalID << std::endl;
-    std::cout << "===== average wholeUpdateTime:\t" << wholeUpdataTime * 1000.0 / this->dataPtr->iterations << "\tms =====\t" << this->gazeboLocalID << std::endl;
+    std::cout << "===== average wholeUpdateTime:\t" << (wholeUpdataTime - wholeUpdataTime2) * 1000.0 / (this->dataPtr->iterations - start_iterations) << "\tms =====\t" << this->gazeboLocalID << std::endl;
-    std::cout << "===== average RTF:\t" << this->GetSimTime().Double() / this->GetRealTime().Double() << "\t =====\t" << this->gazeboLocalID << std::endl;
+    std::cout << "===== average RTF:\t" << (this->GetSimTime().Double() - simtime) / (this->GetRealTime().Double() - realtime) << "\t =====\t" << this->gazeboLocalID << std::endl;
     // }
   }
 #endif

Gazebo_Distributed_MPI/mpi_run/MPI_Gazebo_end.sh

@@ -3,10 +3,12 @@
 #   Author: Zhang Shuai                                                                                                             #
 #   Date:   2019-08-26                                                                                                              #
 #   Description:    End a MPI Gazebo simulation task                                                                                #
-#   Usage:  ./MPI_Gazebo_end.sh [hostfile]                                                                                          #
+#   Usage:  ./MPI_Gazebo_end.sh [hostfile] [shell's path]                                                                           #
+#   Example:    ./MPI_Gazebo_launch.sh hostfile ~/Git/Gazebo_Distributed_MPI/mpi_run                                                #
 #####################################################################################################################################
 
 host_file=$1
+shell_path=$2
 
 host_count=0
 hosts=()
@@ -29,10 +31,10 @@ do
     echo "host_name:${hosts[$i]}"
 done
 
-#登入各节点kill相关进程以结束仿真（1.目前方式比较暴力，后续改进；2.cd ~/Git/Gazebo_Distributed_MPI/mpi_run 还要进行灵活性优化）
+#登入各节点kill相关进程以结束仿真（1.目前方式比较暴力，后续改进。）
 for((i=0;i<host_count;i++))
 do
-    ssh -f -n ${hosts[$i]} > /dev/null 2>&1 "cd ~/Git/Gazebo_Distributed_MPI/mpi_run;
+    ssh -f -n ${hosts[$i]} > /dev/null 2>&1 "cd $shell_path;
     ./kill.sh;
     ./kill.sh;
     ./kill.sh;

Gazebo_Distributed_MPI/mpi_run/MPI_Gazebo_launch.sh

@@ -1,22 +1,26 @@
 #!/bin/bash
-#####################################################################################################################################
+###################################################################################################################################################
-#   Author: Zhang Shuai                                                                                                             #
+#   Author: Zhang Shuai                                                                                                                           #
-#   Date:   2019-05-23                                                                                                              #
+#   Date:   2019-05-23                                                                                                                            #
-#   Description:    launch a MPI Gazebo simulation task                                                                             #
+#   Description:    launch a MPI Gazebo simulation task                                                                                           #
-#   Usage:  ./MPI_Gazebo_launch.sh [ros packdge's name] [launch file's name] [workspace's path] [world's path and name] [hostfile]  #
+#   Usage:  ./MPI_Gazebo_launch.sh [ros packdge's name] [launch file's name] [workspace's path] [world's path and name] [hostfile] [shell's path] #
-#####################################################################################################################################
+#   Example:    ./MPI_Gazebo_launch.sh rosplane_sim fixedwing_text_three_100_withoutfast_mpi.launch ~/zhangshuai/DA                               #
+#               ~/zhangshuai/DA/src/da/rosplane/rosplane_sim/worlds/flying_mpi_100.world hostfile ~/Git/Gazebo_Distributed_MPI/mpi_run            #
+###################################################################################################################################################
 
 packdge_name=$1
 launch_file_name=$2
 workspace_path=$3
 world_file=$4
 host_file=$5
+shell_path=$6
 
 echo $packdge_name
 echo $launch_file_name
 echo $workspace_path
 echo $world_file
 echo $host_file
+echo $shell_path
 
 host_count=0
 hosts=()
@@ -39,26 +43,29 @@ do
     echo "host_name:${hosts[$i]}"
 done
 
-#登入各节点启动roscore    （source还有改进空间，ROS运行的工作目录应该作为参数传进来）
+#登入各节点启动roscore
 for((i=0;i<host_count;i++))
 do
     ssh -f -n ${hosts[$i]} "source $workspace_path/devel/setup.bash;
+    export ROS_HOSTNAME=localhost;
     roscore;
-    echo roscore_done!"
+    echo roscore_done!;
+    rosparam set /use_sim_time true;
+    rosparam get /use_sim_time"
     echo "${hosts[$i]}:roscore_good"
 done
 
 sleep 5s
 
-#登入第一个节点启动MPI的gzserver，并成为各自节点上的ROS node
+#登入第一个节点启动MPI的gzserver，并成为各自节点上的ROS node     ##  btl_tcp_if_exclude / btl_tcp_if_include
 ssh -f -n ${hosts[0]} "cd ~/Git/Gazebo_Distributed_MPI/mpi_run;
-mpiexec --mca btl_tcp_if_exclude docker0 -hostfile $host_file -np 1 mygzserver $world_file $workspace_path : -np 1 mygzserver $world_file $workspace_path;
+mpiexec --mca btl_tcp_if_include eno2d1 -hostfile $host_file -np 1 mygzserver $world_file $workspace_path : -np 1 mygzserver $world_file $workspace_path;
 echo mpiexec_done!"
 echo "${hosts[0]}:mpiexec_good"
 
 sleep 10s
 
-#登入各节点roslaunch加载模型（source还有改进空间，ROS运行的工作目录应该作为参数传进来）
+#登入各节点roslaunch加载模型
 for((i=0;i<host_count;i++))
 do
     ssh -f -n ${hosts[$i]} "source $workspace_path/devel/setup.bash;
@@ -70,7 +77,7 @@ do
     echo "${hosts[$i]}:roslaunch_good"
 done
 
-sleep 20s
+sleep 100s
 
 #登入各节点开始仿真
 for((i=0;i<host_count;i++))
@@ -83,10 +90,10 @@ done
 
 sleep 5m
 
-#登入各节点kill相关进程以结束仿真（1.目前方式比较暴力，后续改进；2.cd ~/Git/Gazebo_Distributed_MPI/mpi_run 还要进行灵活性优化）
+#登入各节点kill相关进程以结束仿真（1.目前方式比较暴力，后续改进。）
 for((i=0;i<host_count;i++))
 do
-    ssh -f -n ${hosts[$i]} > /dev/null 2>&1 "cd ~/Git/Gazebo_Distributed_MPI/mpi_run;
+    ssh -f -n ${hosts[$i]} > /dev/null 2>&1 "cd $shell_path;
     ./kill.sh;
     ./kill.sh;
     ./kill.sh;

Gazebo_Distributed_MPI/mpi_run/mygzserver

@@ -5,5 +5,6 @@ source /opt/ros/kinetic/setup.bash
 source $2/devel/setup.bash
 
 export DISPLAY=:0.0
+export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/lib:/usr/local/lib/gazebo-7/plugins:/opt/ros/kinetic/lib:/opt/ros/kinetic/lib/x86_64-linux-gnu
 
 /usr/local/bin/gzserver -u -e ode --verbose $1 -s /opt/ros/kinetic/lib/libgazebo_ros_paths_plugin.so -s /opt/ros/kinetic/lib/libgazebo_ros_api_plugin.so

Gazebo_Hector_Test/src/hector_quadrotor/hector_quadrotor_gazebo/launch/hector_10_single_gazebo_mpi_spawn_test_seperate_takeoff.launch

@@ -0,0 +1,128 @@
+<!-- This is a launch file that runs the bare minimum requirements to get -->
+<!-- gazebo running for a fixed-wing aircraft -->
+
+<launch>
+
+  <group ns="bebop_0">
+    <include file="$(find hector_quadrotor_gazebo)/launch/spawn_quadrotor.launch">
+      <arg name="name" value="bebop_0" />
+      <arg name="model" value="$(find hector_quadrotor_description)/urdf/quadrotor_with_downward_cam.gazebo.xacro"/>
+      <arg name="tf_prefix" value="bebop_0" />
+      <arg name="x" value="0.0" />
+      <arg name="y" value="0.0" />
+      <arg name="z" value="0.186" />
+    </include>
+    <node name="simple_takeoff" pkg="hector" type="hector_simple_takeoff"/>
+  </group>
+
+  <group ns="bebop_1">
+    <include file="$(find hector_quadrotor_gazebo)/launch/spawn_quadrotor.launch">
+      <arg name="name" value="bebop_1" />
+      <arg name="model" value="$(find hector_quadrotor_description)/urdf/quadrotor_with_downward_cam.gazebo.xacro"/>
+      <arg name="tf_prefix" value="bebop_1" />
+      <arg name="x" value="0.0" />
+      <arg name="y" value="5.0" />
+      <arg name="z" value="0.186" />
+    </include>
+    <node name="simple_takeoff" pkg="hector" type="hector_simple_takeoff"/>
+  </group>
+
+  <group ns="bebop_2">
+    <include file="$(find hector_quadrotor_gazebo)/launch/spawn_quadrotor.launch">
+      <arg name="name" value="bebop_2" />
+      <arg name="model" value="$(find hector_quadrotor_description)/urdf/quadrotor_with_downward_cam.gazebo.xacro"/>
+      <arg name="tf_prefix" value="bebop_2" />
+      <arg name="x" value="0.0" />
+      <arg name="y" value="10.0" />
+      <arg name="z" value="0.186" />
+    </include>
+    <node name="simple_takeoff" pkg="hector" type="hector_simple_takeoff"/>
+  </group>
+
+  <group ns="bebop_3">
+    <include file="$(find hector_quadrotor_gazebo)/launch/spawn_quadrotor.launch">
+      <arg name="name" value="bebop_3" />
+      <arg name="model" value="$(find hector_quadrotor_description)/urdf/quadrotor_with_downward_cam.gazebo.xacro"/>
+      <arg name="tf_prefix" value="bebop_3" />
+      <arg name="x" value="0.0" />
+      <arg name="y" value="15.0" />
+      <arg name="z" value="0.186" />
+    </include>
+    <node name="simple_takeoff" pkg="hector" type="hector_simple_takeoff"/>
+  </group>
+
+  <group ns="bebop_4">
+    <include file="$(find hector_quadrotor_gazebo)/launch/spawn_quadrotor.launch">
+      <arg name="name" value="bebop_4" />
+      <arg name="model" value="$(find hector_quadrotor_description)/urdf/quadrotor_with_downward_cam.gazebo.xacro"/>
+      <arg name="tf_prefix" value="bebop_4" />
+      <arg name="x" value="0.0" />
+      <arg name="y" value="20.0" />
+      <arg name="z" value="0.186" />
+    </include>
+    <node name="simple_takeoff" pkg="hector" type="hector_simple_takeoff"/>
+  </group>
+
+  <group ns="bebop_5">
+    <include file="$(find hector_quadrotor_gazebo)/launch/spawn_quadrotor.launch">
+      <arg name="name" value="bebop_5" />
+      <arg name="model" value="$(find hector_quadrotor_description)/urdf/quadrotor_with_downward_cam.gazebo.xacro"/>
+      <arg name="tf_prefix" value="bebop_5" />
+      <arg name="x" value="0.0" />
+      <arg name="y" value="25.0" />
+      <arg name="z" value="0.186" />
+    </include>
+    <node name="simple_takeoff" pkg="hector" type="hector_simple_takeoff"/>
+  </group>
+
+  <group ns="bebop_6">
+    <include file="$(find hector_quadrotor_gazebo)/launch/spawn_quadrotor.launch">
+      <arg name="name" value="bebop_6" />
+      <arg name="model" value="$(find hector_quadrotor_description)/urdf/quadrotor_with_downward_cam.gazebo.xacro"/>
+      <arg name="tf_prefix" value="bebop_6" />
+      <arg name="x" value="0.0" />
+      <arg name="y" value="30.0" />
+      <arg name="z" value="0.186" />
+    </include>
+    <node name="simple_takeoff" pkg="hector" type="hector_simple_takeoff"/>
+  </group>
+
+  <group ns="bebop_7">
+    <include file="$(find hector_quadrotor_gazebo)/launch/spawn_quadrotor.launch">
+      <arg name="name" value="bebop_7" />
+      <arg name="model" value="$(find hector_quadrotor_description)/urdf/quadrotor_with_downward_cam.gazebo.xacro"/>
+      <arg name="tf_prefix" value="bebop_7" />
+      <arg name="x" value="0.0" />
+      <arg name="y" value="35.0" />
+      <arg name="z" value="0.186" />
+    </include>
+    <node name="simple_takeoff" pkg="hector" type="hector_simple_takeoff"/>
+  </group>
+
+  <group ns="bebop_8">
+    <include file="$(find hector_quadrotor_gazebo)/launch/spawn_quadrotor.launch">
+      <arg name="name" value="bebop_8" />
+      <arg name="model" value="$(find hector_quadrotor_description)/urdf/quadrotor_with_downward_cam.gazebo.xacro"/>
+      <arg name="tf_prefix" value="bebop_8" />
+      <arg name="x" value="0.0" />
+      <arg name="y" value="40.0" />
+      <arg name="z" value="0.186" />
+    </include>
+    <node name="simple_takeoff" pkg="hector" type="hector_simple_takeoff"/>
+  </group>
+
+  <group ns="bebop_9">
+    <include file="$(find hector_quadrotor_gazebo)/launch/spawn_quadrotor.launch">
+      <arg name="name" value="bebop_9" />
+      <arg name="model" value="$(find hector_quadrotor_description)/urdf/quadrotor_with_downward_cam.gazebo.xacro"/>
+      <arg name="tf_prefix" value="bebop_9" />
+      <arg name="x" value="0.0" />
+      <arg name="y" value="45.0" />
+      <arg name="z" value="0.186" />
+    </include>
+    <node name="simple_takeoff" pkg="hector" type="hector_simple_takeoff"/>
+  </group>
+
+  <!-- <node name="simple_takeoff" pkg="hector" type="hector_simple_takeoff"/> -->
+
+</launch>