Hi,
I’m trying to create a coaxial octocopter for a research project. I’m trying start start out with creating a very simple model to fly in a Gazebo simulation, but I have some problems, since I’m not that experienced with either PX4 or Gazebo. I have managed to load the simple model into Gazebo and have 8 motors that all spins, but as soon as I try to takeoff the drone will flip over. I’m using version 1.13.0 of PX4.
I’m using the following files to try and create the drone, if somebody wants to replicate it. Let me know if anything is missing. Most of them was modified from other code I have found, so any help in improvements in them are appreciated 
The mixer file
# Octo coaxial
R: 8c
The geometry file located in init.d-posix being used.
#!/bin/sh
#
# @name Generic 10" Octo coaxial geometry
#
# @type Octorotor Coaxial
# @class Copter
#
# @output MAIN1 motor 1
# @output MAIN2 motor 2
# @output MAIN3 motor 3
# @output MAIN4 motor 4
# @output MAIN5 motor 5
# @output MAIN6 motor 6
# @output MAIN7 motor 7
# @output MAIN8 motor 8
#
# @maintainer Lorenz Meier <lorenz@px4.io>
#
# @board bitcraze_crazyflie exclude
#
. ${R}etc/init.d/rc.mc_defaults
set MIXER octo_cox
set PWM_OUT 12345678
The SDF file being used:
<?xml version='1.0'?>
<sdf version='1.6'>
<model name='octo_cox'>
<!--Drone body -->
<link name='base_link'>
<pose>0 0 0 0 -0 0</pose>
<inertial>
<pose>0 0 0 0 -0 0</pose>
<mass>6</mass>
<inertia>
<ixx>0.762625</ixx>
<ixy>0</ixy>
<ixz>0</ixz>
<iyy>0.762625</iyy>
<iyz>0</iyz>
<izz>1.369</izz>
</inertia>
</inertial>
<collision name='base_link_inertia_collision'>
<pose>0 0 0 0 -0 0</pose>
<geometry>
<box>
<size>0.74 0.74 0.25</size>
</box>
</geometry>
<surface>
<contact>
<ode>
<min_depth>0.001</min_depth>
<max_vel>0</max_vel>
</ode>
</contact>
<friction>
<ode/>
</friction>
</surface>
</collision>
<visual name='base_link_inertia_visual'>
<pose>0 0 0.125 1.57 0 0</pose>
<geometry>
<mesh>
<scale>0.3 0.3 0.3</scale>
<uri>model://octo_cox/meshes/Part1.dae</uri>
</mesh>
</geometry>
</visual>
<gravity>1</gravity>
<velocity_decay/>
</link>
<link name='/imu_link'>
<pose>0 0 0 0 -0 0</pose>
<inertial>
<pose>0 0 0 0 -0 0</pose>
<mass>0.015</mass>
<inertia>
<ixx>1e-05</ixx>
<ixy>0</ixy>
<ixz>0</ixz>
<iyy>1e-05</iyy>
<iyz>0</iyz>
<izz>1e-05</izz>
</inertia>
</inertial>
</link>
<joint name='/imu_joint' type='revolute'>
<child>/imu_link</child>
<parent>base_link</parent>
<axis>
<xyz>1 0 0</xyz>
<limit>
<lower>0</lower>
<upper>0</upper>
<effort>0</effort>
<velocity>0</velocity>
</limit>
<dynamics>
<spring_reference>0</spring_reference>
<spring_stiffness>0</spring_stiffness>
</dynamics>
<use_parent_model_frame>1</use_parent_model_frame>
</axis>
</joint>
<!-- Rotor 0 (CCW) -->
<link name='rotor_0'>
<pose>0.520429 -0.435000 0.220 0 -0 0</pose>
<inertial>
<pose>0 0 0 0 -0 0</pose>
<mass>0.05</mass>
<inertia>
<ixx>9.75e-07</ixx>
<ixy>0</ixy>
<ixz>0</ixz>
<iyy>0.000273104</iyy>
<iyz>0</iyz>
<izz>0.000274004</izz>
</inertia>
</inertial>
<collision name='rotor_0_collision'>
<pose>0 0 0 0 -0 0</pose>
<geometry>
<cylinder>
<length>0.005</length>
<radius>0.128</radius>
</cylinder>
</geometry>
<surface>
<contact>
<ode/>
</contact>
<friction>
<ode/>
</friction>
</surface>
</collision>
<visual name='rotor_0_visual'>
<pose>0 0 0 0 -0 0</pose>
<geometry>
<mesh>
<scale>1.5 1.5 1.5</scale>
<uri>model://sdu_description/meshes/prop_ccw.dae</uri>
</mesh>
</geometry>
<material>
<script>
<name>Gazebo/DarkGrey</name>
<uri>file://media/materials/scripts/gazebo.material</uri>
</script>
</material>
</visual>
<gravity>1</gravity>
<velocity_decay/>
</link>
<joint name='rotor_0_joint' type='revolute'>
<child>rotor_0</child>
<parent>base_link</parent>
<axis>
<xyz>0 0 1</xyz>
<limit>
<lower>-1e+16</lower>
<upper>1e+16</upper>
</limit>
<dynamics>
<spring_reference>0</spring_reference>
<spring_stiffness>0</spring_stiffness>
</dynamics>
<use_parent_model_frame>1</use_parent_model_frame>
</axis>
</joint>
<!-- Rotor 1 (CW) -->
<link name='rotor_1'>
<pose>0.550429 0.535000 0.220 0 -0 0</pose>
<inertial>
<pose>0 0 0 0 -0 0</pose>
<mass>0.05</mass>
<inertia>
<ixx>9.75e-07</ixx>
<ixy>0</ixy>
<ixz>0</ixz>
<iyy>0.000273104</iyy>
<iyz>0</iyz>
<izz>0.000274004</izz>
</inertia>
</inertial>
<collision name='rotor_1_collision'>
<pose>0 0 0 0 -0 0</pose>
<geometry>
<cylinder>
<length>0.005</length>
<radius>0.128</radius>
</cylinder>
</geometry>
<surface>
<contact>
<ode/>
</contact>
<friction>
<ode/>
</friction>
</surface>
</collision>
<visual name='rotor_1_visual'>
<pose>0 0 0 0 -0 0</pose>
<geometry>
<mesh>
<scale>1.5 1.5 1.5</scale>
<uri>model://sdu_description/meshes/prop_cw.dae</uri>
</mesh>
</geometry>
<material>
<script>
<name>Gazebo/Blue</name>
<uri>file://media/materials/scripts/gazebo.material</uri>
</script>
</material>
</visual>
<gravity>1</gravity>
<velocity_decay/>
</link>
<joint name='rotor_1_joint' type='revolute'>
<child>rotor_1</child>
<parent>base_link</parent>
<axis>
<xyz>0 0 1</xyz>
<limit>
<lower>-1e+16</lower>
<upper>1e+16</upper>
</limit>
<dynamics>
<spring_reference>0</spring_reference>
<spring_stiffness>0</spring_stiffness>
</dynamics>
<use_parent_model_frame>1</use_parent_model_frame>
</axis>
</joint>
<!-- Rotor 2 (CCW) -->
<link name='rotor_2'>
<pose>-0.40 0.535000 0.220 0 -0 0</pose>
<inertial>
<pose>0 0 0 0 -0 0</pose>
<mass>0.05</mass>
<inertia>
<ixx>9.75e-07</ixx>
<ixy>0</ixy>
<ixz>0</ixz>
<iyy>0.000273104</iyy>
<iyz>0</iyz>
<izz>0.000274004</izz>
</inertia>
</inertial>
<collision name='rotor_2_collision'>
<pose>0 0 0 0 -0 0</pose>
<geometry>
<cylinder>
<length>0.005</length>
<radius>0.128</radius>
</cylinder>
</geometry>
<surface>
<contact>
<ode/>
</contact>
<friction>
<ode/>
</friction>
</surface>
</collision>
<visual name='rotor_2_visual'>
<pose>0 0 0 0 -0 0</pose>
<geometry>
<mesh>
<scale>1.5 1.5 1.5</scale>
<uri>model://sdu_description/meshes/prop_ccw.dae</uri>
</mesh>
</geometry>
<material>
<script>
<name>Gazebo/DarkGrey</name>
<uri>file://media/materials/scripts/gazebo.material</uri>
</script>
</material>
</visual>
<gravity>1</gravity>
<velocity_decay/>
</link>
<joint name='rotor_2_joint' type='revolute'>
<child>rotor_2</child>
<parent>base_link</parent>
<axis>
<xyz>0 0 1</xyz>
<limit>
<lower>-1e+16</lower>
<upper>1e+16</upper>
</limit>
<dynamics>
<spring_reference>0</spring_reference>
<spring_stiffness>0</spring_stiffness>
</dynamics>
<use_parent_model_frame>1</use_parent_model_frame>
</axis>
</joint>
<!-- Rotor 3 (CW) -->
<link name='rotor_3'>
<pose>-0.350429 -0.405000 0.220 0 -0 0</pose>
<inertial>
<pose>0 0 0 0 -0 0</pose>
<mass>0.05</mass>
<inertia>
<ixx>9.75e-07</ixx>
<ixy>0</ixy>
<ixz>0</ixz>
<iyy>0.000273104</iyy>
<iyz>0</iyz>
<izz>0.000274004</izz>
</inertia>
</inertial>
<collision name='rotor_3_collision'>
<pose>0 0 0 0 -0 0</pose>
<geometry>
<cylinder>
<length>0.005</length>
<radius>0.128</radius>
</cylinder>
</geometry>
<surface>
<contact>
<ode/>
</contact>
<friction>
<ode/>
</friction>
</surface>
</collision>
<visual name='rotor_3_visual'>
<pose>0 0 0 0 -0 0</pose>
<geometry>
<mesh>
<scale>1.5 1.5 1.5</scale>
<uri>model://sdu_description/meshes/prop_cw.dae</uri>
</mesh>
</geometry>
<material>
<script>
<name>Gazebo/Blue</name>
<uri>file://media/materials/scripts/gazebo.material</uri>
</script>
</material>
</visual>
<gravity>1</gravity>
<velocity_decay/>
</link>
<joint name='rotor_3_joint' type='revolute'>
<child>rotor_3</child>
<parent>base_link</parent>
<axis>
<xyz>0 0 1</xyz>
<limit>
<lower>-1e+16</lower>
<upper>1e+16</upper>
</limit>
<dynamics>
<spring_reference>0</spring_reference>
<spring_stiffness>0</spring_stiffness>
</dynamics>
<use_parent_model_frame>1</use_parent_model_frame>
</axis>
</joint>
<!-- Rotor 4 (CCW) -->
<link name='rotor_4'>
<pose>0.550429 0.535000 0.120 0 -0 0</pose>
<inertial>
<pose>0 0 0 0 -0 0</pose>
<mass>0.05</mass>
<inertia>
<ixx>9.75e-07</ixx>
<ixy>0</ixy>
<ixz>0</ixz>
<iyy>0.000273104</iyy>
<iyz>0</iyz>
<izz>0.000274004</izz>
</inertia>
</inertial>
<collision name='rotor_4_collision'>
<pose>0 0 0 0 -0 0</pose>
<geometry>
<cylinder>
<length>0.005</length>
<radius>0.128</radius>
</cylinder>
</geometry>
<surface>
<contact>
<ode/>
</contact>
<friction>
<ode/>
</friction>
</surface>
</collision>
<visual name='rotor_4_visual'>
<pose>0 0 0 0 -0 0</pose>
<geometry>
<mesh>
<scale>1.5 1.5 1.5</scale>
<uri>model://sdu_description/meshes/prop_ccw.dae</uri>
</mesh>
</geometry>
<material>
<script>
<name>Gazebo/DarkGrey</name>
<uri>file://media/materials/scripts/gazebo.material</uri>
</script>
</material>
</visual>
<gravity>1</gravity>
<velocity_decay/>
</link>
<joint name='rotor_4_joint' type='revolute'>
<child>rotor_4</child>
<parent>base_link</parent>
<axis>
<xyz>0 0 1</xyz>
<limit>
<lower>-1e+16</lower>
<upper>1e+16</upper>
</limit>
<dynamics>
<spring_reference>0</spring_reference>
<spring_stiffness>0</spring_stiffness>
</dynamics>
<use_parent_model_frame>1</use_parent_model_frame>
</axis>
</joint>
<!-- Rotor 5 (CW) -->
<link name='rotor_5'>
<pose>0.520429 -0.435000 0.120 0 -0 0</pose>
<inertial>
<pose>0 0 0 0 -0 0</pose>
<mass>0.05</mass>
<inertia>
<ixx>9.75e-07</ixx>
<ixy>0</ixy>
<ixz>0</ixz>
<iyy>0.000273104</iyy>
<iyz>0</iyz>
<izz>0.000274004</izz>
</inertia>
</inertial>
<collision name='rotor_5_collision'>
<pose>0 0 0 0 -0 0</pose>
<geometry>
<cylinder>
<length>0.005</length>
<radius>0.128</radius>
</cylinder>
</geometry>
<surface>
<contact>
<ode/>
</contact>
<friction>
<ode/>
</friction>
</surface>
</collision>
<visual name='rotor_5_visual'>
<pose>0 0 0 0 -0 0</pose>
<geometry>
<mesh>
<scale>1.5 1.5 1.5</scale>
<uri>model://sdu_description/meshes/prop_cw.dae</uri>
</mesh>
</geometry>
<material>
<script>
<name>Gazebo/Blue</name>
<uri>file://media/materials/scripts/gazebo.material</uri>
</script>
</material>
</visual>
<gravity>1</gravity>
<velocity_decay/>
</link>
<joint name='rotor_5_joint' type='revolute'>
<child>rotor_5</child>
<parent>base_link</parent>
<axis>
<xyz>0 0 1</xyz>
<limit>
<lower>-1e+16</lower>
<upper>1e+16</upper>
</limit>
<dynamics>
<spring_reference>0</spring_reference>
<spring_stiffness>0</spring_stiffness>
</dynamics>
<use_parent_model_frame>1</use_parent_model_frame>
</axis>
</joint>
<!-- Rotor 6 (CCW) -->
<link name='rotor_6'>
<pose>-0.350429 -0.405000 0.120 0 -0 0</pose>
<inertial>
<pose>0 0 0 0 -0 0</pose>
<mass>0.05</mass>
<inertia>
<ixx>9.75e-07</ixx>
<ixy>0</ixy>
<ixz>0</ixz>
<iyy>0.000273104</iyy>
<iyz>0</iyz>
<izz>0.000274004</izz>
</inertia>
</inertial>
<collision name='rotor_6_collision'>
<pose>0 0 0 0 -0 0</pose>
<geometry>
<cylinder>
<length>0.005</length>
<radius>0.128</radius>
</cylinder>
</geometry>
<surface>
<contact>
<ode/>
</contact>
<friction>
<ode/>
</friction>
</surface>
</collision>
<visual name='rotor_6_visual'>
<pose>0 0 0 0 -0 0</pose>
<geometry>
<mesh>
<scale>1.5 1.5 1.5</scale>
<uri>model://sdu_description/meshes/prop_ccw.dae</uri>
</mesh>
</geometry>
<material>
<script>
<name>Gazebo/DarkGrey</name>
<uri>file://media/materials/scripts/gazebo.material</uri>
</script>
</material>
</visual>
<gravity>1</gravity>
<velocity_decay/>
</link>
<joint name='rotor_6_joint' type='revolute'>
<child>rotor_6</child>
<parent>base_link</parent>
<axis>
<xyz>0 0 1</xyz>
<limit>
<lower>-1e+16</lower>
<upper>1e+16</upper>
</limit>
<dynamics>
<spring_reference>0</spring_reference>
<spring_stiffness>0</spring_stiffness>
</dynamics>
<use_parent_model_frame>1</use_parent_model_frame>
</axis>
</joint>
<!-- Rotor 7 (CW) -->
<link name='rotor_7'>
<pose>-0.40 0.535000 0.120 0 -0 0</pose>
<inertial>
<pose>0 0 0 0 -0 0</pose>
<mass>0.05</mass>
<inertia>
<ixx>9.75e-07</ixx>
<ixy>0</ixy>
<ixz>0</ixz>
<iyy>0.000273104</iyy>
<iyz>0</iyz>
<izz>0.000274004</izz>
</inertia>
</inertial>
<collision name='rotor_7_collision'>
<pose>0 0 0 0 -0 0</pose>
<geometry>
<cylinder>
<length>0.005</length>
<radius>0.128</radius>
</cylinder>
</geometry>
<surface>
<contact>
<ode/>
</contact>
<friction>
<ode/>
</friction>
</surface>
</collision>
<visual name='rotor_7_visual'>
<pose>0 0 0 0 -0 0</pose>
<geometry>
<mesh>
<scale>1.5 1.5 1.5</scale>
<uri>model://sdu_description/meshes/prop_cw.dae</uri>
</mesh>
</geometry>
<material>
<script>
<name>Gazebo/Blue</name>
<uri>file://media/materials/scripts/gazebo.material</uri>
</script>
</material>
</visual>
<gravity>1</gravity>
<velocity_decay/>
</link>
<joint name='rotor_7_joint' type='revolute'>
<child>rotor_7</child>
<parent>base_link</parent>
<axis>
<xyz>0 0 1</xyz>
<limit>
<lower>-1e+16</lower>
<upper>1e+16</upper>
</limit>
<dynamics>
<spring_reference>0</spring_reference>
<spring_stiffness>0</spring_stiffness>
</dynamics>
<use_parent_model_frame>1</use_parent_model_frame>
</axis>
</joint>
<plugin name='rosbag' filename='libgazebo_multirotor_base_plugin.so'>
<robotNamespace/>
<linkName>base_link</linkName>
<rotorVelocitySlowdownSim>10</rotorVelocitySlowdownSim>
</plugin>
<plugin name='motor_model_0' filename='libgazebo_motor_model.so'>
<robotNamespace/>
<jointName>rotor_0_joint</jointName>
<linkName>rotor_0</linkName>
<turningDirection>ccw</turningDirection>
<timeConstantUp>0.0125</timeConstantUp>
<timeConstantDown>0.025</timeConstantDown>
<maxRotVelocity>1100</maxRotVelocity>
<motorConstant>8.54858e-06</motorConstant>
<momentConstant>0.06</momentConstant>
<commandSubTopic>/gazebo/command/motor_speed</commandSubTopic>
<motorNumber>0</motorNumber>
<rotorDragCoefficient>0.000806428</rotorDragCoefficient>
<rollingMomentCoefficient>1e-06</rollingMomentCoefficient>
<motorSpeedPubTopic>/motor_speed/0</motorSpeedPubTopic>
<rotorVelocitySlowdownSim>10</rotorVelocitySlowdownSim>
</plugin>
<plugin name='motor_model_1' filename='libgazebo_motor_model.so'>
<robotNamespace/>
<jointName>rotor_1_joint</jointName>
<linkName>rotor_1</linkName>
<turningDirection>cw</turningDirection>
<timeConstantUp>0.0125</timeConstantUp>
<timeConstantDown>0.025</timeConstantDown>
<maxRotVelocity>1100</maxRotVelocity>
<motorConstant>8.54858e-06</motorConstant>
<momentConstant>0.06</momentConstant>
<commandSubTopic>/gazebo/command/motor_speed</commandSubTopic>
<motorNumber>1</motorNumber>
<rotorDragCoefficient>0.000806428</rotorDragCoefficient>
<rollingMomentCoefficient>1e-06</rollingMomentCoefficient>
<motorSpeedPubTopic>/motor_speed/1</motorSpeedPubTopic>
<rotorVelocitySlowdownSim>10</rotorVelocitySlowdownSim>
</plugin>
<plugin name='motor_model_2' filename='libgazebo_motor_model.so'>
<robotNamespace/>
<jointName>rotor_2_joint</jointName>
<linkName>rotor_2</linkName>
<turningDirection>ccw</turningDirection>
<timeConstantUp>0.0125</timeConstantUp>
<timeConstantDown>0.025</timeConstantDown>
<maxRotVelocity>1100</maxRotVelocity>
<motorConstant>8.54858e-06</motorConstant>
<momentConstant>0.06</momentConstant>
<commandSubTopic>/gazebo/command/motor_speed</commandSubTopic>
<motorNumber>2</motorNumber>
<rotorDragCoefficient>0.000806428</rotorDragCoefficient>
<rollingMomentCoefficient>1e-06</rollingMomentCoefficient>
<motorSpeedPubTopic>/motor_speed/2</motorSpeedPubTopic>
<rotorVelocitySlowdownSim>10</rotorVelocitySlowdownSim>
</plugin>
<plugin name='motor_model_3' filename='libgazebo_motor_model.so'>
<robotNamespace/>
<jointName>rotor_3_joint</jointName>
<linkName>rotor_3</linkName>
<turningDirection>cw</turningDirection>
<timeConstantUp>0.0125</timeConstantUp>
<timeConstantDown>0.025</timeConstantDown>
<maxRotVelocity>1100</maxRotVelocity>
<motorConstant>8.54858e-06</motorConstant>
<momentConstant>0.06</momentConstant>
<commandSubTopic>/gazebo/command/motor_speed</commandSubTopic>
<motorNumber>3</motorNumber>
<rotorDragCoefficient>0.000806428</rotorDragCoefficient>
<rollingMomentCoefficient>1e-06</rollingMomentCoefficient>
<motorSpeedPubTopic>/motor_speed/3</motorSpeedPubTopic>
<rotorVelocitySlowdownSim>10</rotorVelocitySlowdownSim>
</plugin>
<plugin name='motor_model_4' filename='libgazebo_motor_model.so'>
<robotNamespace/>
<jointName>rotor_4_joint</jointName>
<linkName>rotor_4</linkName>
<turningDirection>ccw</turningDirection>
<timeConstantUp>0.0125</timeConstantUp>
<timeConstantDown>0.025</timeConstantDown>
<maxRotVelocity>1100</maxRotVelocity>
<motorConstant>8.54858e-06</motorConstant>
<momentConstant>0.06</momentConstant>
<commandSubTopic>/gazebo/command/motor_speed</commandSubTopic>
<motorNumber>4</motorNumber>
<rotorDragCoefficient>0.000806428</rotorDragCoefficient>
<rollingMomentCoefficient>1e-06</rollingMomentCoefficient>
<motorSpeedPubTopic>/motor_speed/4</motorSpeedPubTopic>
<rotorVelocitySlowdownSim>10</rotorVelocitySlowdownSim>
</plugin>
<plugin name='motor_model_5' filename='libgazebo_motor_model.so'>
<robotNamespace/>
<jointName>rotor_5_joint</jointName>
<linkName>rotor_5</linkName>
<turningDirection>cw</turningDirection>
<timeConstantUp>0.0125</timeConstantUp>
<timeConstantDown>0.025</timeConstantDown>
<maxRotVelocity>1100</maxRotVelocity>
<motorConstant>8.54858e-06</motorConstant>
<momentConstant>0.06</momentConstant>
<commandSubTopic>/gazebo/command/motor_speed</commandSubTopic>
<motorNumber>5</motorNumber>
<rotorDragCoefficient>0.000806428</rotorDragCoefficient>
<rollingMomentCoefficient>1e-06</rollingMomentCoefficient>
<motorSpeedPubTopic>/motor_speed/5</motorSpeedPubTopic>
<rotorVelocitySlowdownSim>10</rotorVelocitySlowdownSim>
</plugin>
<plugin name='motor_model_6' filename='libgazebo_motor_model.so'>
<robotNamespace/>
<jointName>rotor_6_joint</jointName>
<linkName>rotor_6</linkName>
<turningDirection>ccw</turningDirection>
<timeConstantUp>0.0125</timeConstantUp>
<timeConstantDown>0.025</timeConstantDown>
<maxRotVelocity>1100</maxRotVelocity>
<motorConstant>8.54858e-06</motorConstant>
<momentConstant>0.06</momentConstant>
<commandSubTopic>/gazebo/command/motor_speed</commandSubTopic>
<motorNumber>6</motorNumber>
<rotorDragCoefficient>0.000806428</rotorDragCoefficient>
<rollingMomentCoefficient>1e-06</rollingMomentCoefficient>
<motorSpeedPubTopic>/motor_speed/6</motorSpeedPubTopic>
<rotorVelocitySlowdownSim>10</rotorVelocitySlowdownSim>
</plugin>
<plugin name='motor_model_7' filename='libgazebo_motor_model.so'>
<robotNamespace/>
<jointName>rotor_7_joint</jointName>
<linkName>rotor_7</linkName>
<turningDirection>cw</turningDirection>
<timeConstantUp>0.0125</timeConstantUp>
<timeConstantDown>0.025</timeConstantDown>
<maxRotVelocity>1100</maxRotVelocity>
<motorConstant>8.54858e-06</motorConstant>
<momentConstant>0.06</momentConstant>
<commandSubTopic>/gazebo/command/motor_speed</commandSubTopic>
<motorNumber>7</motorNumber>
<rotorDragCoefficient>0.000806428</rotorDragCoefficient>
<rollingMomentCoefficient>1e-06</rollingMomentCoefficient>
<motorSpeedPubTopic>/motor_speed/7</motorSpeedPubTopic>
<rotorVelocitySlowdownSim>10</rotorVelocitySlowdownSim>
</plugin>
<model name='gps0'>
<link name='link'>
<pose>0 0 0.125 0 -0 0</pose>
<inertial>
<pose>0 0 0 0 -0 0</pose>
<mass>0.01</mass>
<inertia>
<ixx>2.1733e-06</ixx>
<ixy>0</ixy>
<ixz>0</ixz>
<iyy>2.1733e-06</iyy>
<iyz>0</iyz>
<izz>1.8e-07</izz>
</inertia>
</inertial>
<visual name='visual'>
<geometry>
<cylinder>
<radius>0.01</radius>
<length>0.002</length>
</cylinder>
</geometry>
<material>
<script>
<name>Gazebo/Black</name>
<uri>__default__</uri>
</script>
</material>
</visual>
<sensor name='gps' type='gps'>
<pose>0 0 0 0 -0 0</pose>
<plugin name='gps_plugin' filename='libgazebo_gps_plugin.so'>
<robotNamespace/>
<gpsNoise>1</gpsNoise>
<gpsXYRandomWalk>2.0</gpsXYRandomWalk>
<gpsZRandomWalk>4.0</gpsZRandomWalk>
<gpsXYNoiseDensity>0.0002</gpsXYNoiseDensity>
<gpsZNoiseDensity>0.0004</gpsZNoiseDensity>
<gpsVXYNoiseDensity>0.2</gpsVXYNoiseDensity>
<gpsVZNoiseDensity>0.4</gpsVZNoiseDensity>
</plugin>
</sensor>
</link>
</model>
<joint name='gps0_joint' type='fixed'>
<parent>base_link</parent>
<child>gps0::link</child>
</joint>
<plugin name='groundtruth_plugin' filename='libgazebo_groundtruth_plugin.so'>
<robotNamespace/>
</plugin>
<plugin name='magnetometer_plugin' filename='libgazebo_magnetometer_plugin.so'>
<robotNamespace/>
<pubRate>20</pubRate>
<noiseDensity>0.0004</noiseDensity>
<randomWalk>6.4e-06</randomWalk>
<biasCorrelationTime>600</biasCorrelationTime>
<magTopic>/mag</magTopic>
</plugin>
<plugin name='barometer_plugin' filename='libgazebo_barometer_plugin.so'>
<robotNamespace/>
<pubRate>10</pubRate>
<baroTopic>/baro</baroTopic>
</plugin>
<plugin name='parachute_plugin' filename='libgazebo_parachute_plugin.so'>
<robotNamespace/>
<commandSubTopic>/gazebo/command/motor_speed</commandSubTopic>
<motorNumber>6</motorNumber>
</plugin>
<plugin name='mavlink_interface' filename='libgazebo_mavlink_interface.so'>
<robotNamespace></robotNamespace>
<imuSubTopic>/imu</imuSubTopic>
<magSubTopic>/mag</magSubTopic>
<baroSubTopic>/baro</baroSubTopic>
<mavlink_addr>INADDR_ANY</mavlink_addr>
<mavlink_udp_port>14560</mavlink_udp_port>
<mavlink_tcp_port>4560</mavlink_tcp_port>
<serialEnabled>false</serialEnabled>
<serialDevice>/dev/ttyACM0</serialDevice>
<baudRate>921600</baudRate>
<qgc_addr>INADDR_ANY</qgc_addr>
<qgc_udp_port>14550</qgc_udp_port>
<sdk_addr>INADDR_ANY</sdk_addr>
<sdk_udp_port>14540</sdk_udp_port>
<hil_mode>0</hil_mode>
<hil_state_level>0</hil_state_level>
<vehicle_is_tailsitter>0</vehicle_is_tailsitter>
<send_vision_estimation>1</send_vision_estimation>
<send_odometry>0</send_odometry>
<enable_lockstep>1</enable_lockstep>
<use_tcp>1</use_tcp>
<motorSpeedCommandPubTopic>/gazebo/command/motor_speed</motorSpeedCommandPubTopic>
<control_channels>
<channel name="rotor0">
<input_index>0</input_index>
<input_offset>0</input_offset>
<input_scaling>1500</input_scaling>
<zero_position_disarmed>0</zero_position_disarmed>
<zero_position_armed>100</zero_position_armed>
<joint_control_type>velocity</joint_control_type>
<joint_name>rotor_0_joint</joint_name>
</channel>
<channel name="rotor1">
<input_index>1</input_index>
<input_offset>0</input_offset>
<input_scaling>1500</input_scaling>
<zero_position_disarmed>0</zero_position_disarmed>
<zero_position_armed>100</zero_position_armed>
<joint_control_type>velocity</joint_control_type>
<joint_name>rotor_1_joint</joint_name>
</channel>
<channel name="rotor2">
<input_index>2</input_index>
<input_offset>0</input_offset>
<input_scaling>1500</input_scaling>
<zero_position_disarmed>0</zero_position_disarmed>
<zero_position_armed>100</zero_position_armed>
<joint_control_type>velocity</joint_control_type>
<joint_name>rotor_2_joint</joint_name>
</channel>
<channel name="rotor3">
<input_index>3</input_index>
<input_offset>0</input_offset>
<input_scaling>1500</input_scaling>
<zero_position_disarmed>0</zero_position_disarmed>
<zero_position_armed>100</zero_position_armed>
<joint_control_type>velocity</joint_control_type>
<joint_name>rotor_3_joint</joint_name>
</channel>
<channel name="rotor4">
<input_index>4</input_index>
<input_offset>0</input_offset>
<input_scaling>1500</input_scaling>
<zero_position_disarmed>0</zero_position_disarmed>
<zero_position_armed>100</zero_position_armed>
<joint_control_type>velocity</joint_control_type>
<joint_name>rotor_4_joint</joint_name>
</channel>
<channel name="rotor5">
<input_index>5</input_index>
<input_offset>0</input_offset>
<input_scaling>1500</input_scaling>
<zero_position_disarmed>0</zero_position_disarmed>
<zero_position_armed>100</zero_position_armed>
<joint_control_type>velocity</joint_control_type>
<joint_name>rotor_5_joint</joint_name>
</channel>
<channel name="rotor6">
<input_index>6</input_index>
<input_offset>0</input_offset>
<input_scaling>1500</input_scaling>
<zero_position_disarmed>0</zero_position_disarmed>
<zero_position_armed>100</zero_position_armed>
<joint_control_type>velocity</joint_control_type>
<joint_name>rotor_6_joint</joint_name>
</channel>
<channel name="rotor7">
<input_index>7</input_index>
<input_offset>0</input_offset>
<input_scaling>1500</input_scaling>
<zero_position_disarmed>0</zero_position_disarmed>
<zero_position_armed>100</zero_position_armed>
<joint_control_type>velocity</joint_control_type>
<joint_name>rotor_7_joint</joint_name>
</channel>
<channel name='aux1'>
<input_index>8</input_index>
<input_offset>0</input_offset>
<input_scaling>1000</input_scaling>
<zero_position_disarmed>0</zero_position_disarmed>
<zero_position_armed>100</zero_position_armed>
<joint_control_type>velocity</joint_control_type>
</channel>
</control_channels>
</plugin>
<static>0</static>
<plugin name='gazebo_imu_plugin' filename='libgazebo_imu_plugin.so'>
<robotNamespace></robotNamespace>
<linkName>/imu_link</linkName>
<imuTopic>/imu</imuTopic>
<gyroscopeNoiseDensity>0.0003394</gyroscopeNoiseDensity>
<gyroscopeRandomWalk>3.8785e-05</gyroscopeRandomWalk>
<gyroscopeBiasCorrelationTime>1000.0</gyroscopeBiasCorrelationTime>
<gyroscopeTurnOnBiasSigma>0.0087</gyroscopeTurnOnBiasSigma>
<accelerometerNoiseDensity>0.004</accelerometerNoiseDensity>
<accelerometerRandomWalk>0.006</accelerometerRandomWalk>
<accelerometerBiasCorrelationTime>300.0</accelerometerBiasCorrelationTime>
<accelerometerTurnOnBiasSigma>0.196</accelerometerTurnOnBiasSigma>
</plugin>
</model>
</sdf>
Managed to solve it simply by moving the propellers further away from the center. The reason for this is that the geometry file says the propellers is located 0.7 meters away from the center, so moving the that far out made it fly.
