Stability-based Scale Estimation for Monocular SLAM

1. Supplementary materials for the paper

[1] First, read supplementary_materials/Supplementary_Material.pdf for the full derivations ommited in the paper.

[2] Run the MATLAB script supplementary_materials/evaluate_alpha.m for the numerial computation of alpha.

2. Source code

- Prerequisites:

[1] Logitech Extreme 3D Pro joystick. Calibration instruction is available at https://wiki.paparazziuav.org/wiki/Joystick#Joystick_Calibration

[2] If you want to run simulations, you need to install Gazebo (see http://gazebosim.org/tutorials?tut=ros_installing)

[3] If you want to run on a real AR drone 2.0, you need to calibrate its camera. An example is provided in ORB_SLAM2/Examples/Monocular/ardrone_calib.yaml. You can use this file, but I recommend that you do your own calibration to make sure. Calibration instruction is at https://docs.opencv.org/2.4/doc/tutorials/calib3d/camera_calibration/camera_calibration.html

- How to build (Ubuntu 14.04, ROS Indigo):

[1] Clone this repository first:

git clone https://github.com/sunghoon031/stability_scale.git

[2] Clone the AR.Drone ROS driver repository in catkin_ws/src directory, and build:

cd stability_scale/catkin_ws/src
git clone https://github.com/sunghoon031/ardrone_autonomy.git -b indigo-devel
cd ..
rosdep install --from-paths src --ignore-src --rosdistro indigo -y
catkin_make

[3] Clone and build the ORB-SLAM2 from https://github.com/sunghoon031/ORB_SLAM2.git. Please follow the build instructions there

- How to run:

1. Specify the mode

Take a look at the setting file stability_scale/catkin_ws/src/tum_simulator/cvg_sim_gazebo/seong_param.yaml

You need to specify the test_mode to choose between:

• Simulation (1-7) or Real drone (8-12)
• Velocity control using thrust (test_mode 1-2) or Height control using velocity commands (test mode 3-12)
• Please look at seong_param.yaml for more details.

2. Start joystick:

rosparam set joy_node/dev "/dev/input/js0" 
rosrun joy joy_node

- For Gazebo simulation:
cd ~/stability_scale/catkin_ws && source devel/setup.bash
rosrun ardrone_joystick ardrone_teleop

- For real AR drone.
rosparam load ~/stability_scale/catkin_ws/src/tum_simulator/cvg_sim_gazebo/seong_param.yaml /seong_ns
cd ~/stability_scale/catkin_ws && source devel/setup.bash 
rosrun ardrone_joystick ardrone_teleop

3. [Optional] Start dynamic_reconfigure:

cd ~/stability_scale/catkin_ws && source devel/setup.bash
rosrun dynamic_reconfig dynamic_reconfig_node 
rosrun rqt_reconfigure rqt_reconfigure

4. Run ORB-SLAM2

Note that the monocular node subscribes to a topic /camera/image_raw to run node ORB_SLAM2/Mono. So you need to relay the rostopic

rosrun topic_tools relay ardrone/front/image_raw camera/image_raw

- For Gazebo simulation:
cd ~/ORB_SLAM2 && rosrun ORB_SLAM2 Mono Vocabulary/ORBvoc.txt Examples/Monocular/gazebo_calib.yaml 

- For real AR drone. You may want to change the calib.yaml to your own calibration file:
cd ~/ORB_SLAM2 && rosrun ORB_SLAM2 Mono Vocabulary/ORBvoc.txt Examples/Monocular/ardrone_calib.yaml

5. Run the system:

- For Gazebo simulation:
cd ~/stability_scale/catkin_ws && source devel/setup.bash 
roslaunch cvg_sim_gazebo brick_wall.launch 
 	
- For real AR drone. (200Hz real-time update):
cd ~/stability_scale/catkin_ws && source devel/setup.bash 
rosrun ardrone_autonomy ardrone_driver _realtime_navdata:=False _navdata_demo:=0

6. Using the joystick:

• Take off: Button 3
• Land: Button 4
• Start/Stop the adaptive scale estimation: Button 7
• Set the current position as the ground level: Button 8
• Write the scale estimation results to a file: Button 9
• Set the current position as the reference (for scalefree navigation): Button 10
• Increase alpha parameter (only for vertical/horizontal waypoint flight): Button 11
• Decrease alpha parameter (only for vertical/horizontal waypoint flight): Button 12