C++ Ros2-based implementation of the Simultaneous Localization and Mapping (SLAM) approach described in the paper:
"UAV Navigation Using EKF-MonoSLAM Aided by Range-to-Base Measurements" (https://doi.org/10.3390/drones9080570)
The Hybrid VSLAM is composed of the following ROS 2 components and nodes (See https://docs.ros.org/en/galactic/Concepts/About-Composition.html):
ROS 2 components:
- Local SLAM The local SLAM component implements a filter-based, visual SLAM system with a state vector size constrained to ensure real-time operation. On its own, this component generates up-to-metric-scale (world-referenced) estimates of both the robot's state and a local feature map. However, because older features are removed from the state vector to maintain real-time performance, previously visited areas of the environment cannot be recognized. Consequently, the accumulated positional drift cannot be corrected by this process alone.
- Global SLAM Not used.
- Control The control component implements the following high-level control strategies as described in the paper: (i) waypoint control, (ii) visual marker-based control, (iii) area exploration, and (iv) return-to-home.
- Webot package Defines the virtual environment (world) used for experiments, including the UAV (robot) and its low-level controller, simulated using the Webots platform.
- Webot bridge This component interfaces certain sensor readings from the virtual robot with the format required by the SCLAM system.
- Plot (Deprecated) Based on OpenCV-VIZ, the plot component implements a 3d scene of the robot's pose and trajectory as well as a map of visual features.
- Plot2 The plot component implements a 3d scene of the robot's pose and trajectory as well as a map of visual features.
ROS 2 nodes:
- Keyboard Implements a simple command-line interface to interact with the Hybrid VSLAM application.
Dependencies (Tested in: Ubuntu 20.04):
1.- ROS 2 (Galactic), https://docs.ros.org/en/galactic/index.html
2.- Armadillo C++ library (tested with version 11.0.1), http://arma.sourceforge.net/ . Armadillo requires BLAS/OPENBLAS and LAPACK libraries installed
3.- OpenCV with extra modules installed (opencv_contrib) (tested with OpenCV version 4.2.0), https://opencv.org/ The following OpenCV contrib modules are also required or recommended: - VIZ (Required for old Plot module). VIZ requires VTK support (tested with version 8.1.0). - SFM (Recommended). For SFM dependencies check: https://docs.opencv.org/4.x/db/db8/tutorial_sfm_installation.html Note. For compilling OpenCV with SFM, Ceres solver library http://ceres-solver.org/ version < 2.0 is required (tested with 1.14).
4.- GTSAM c++ library (tested with version 4.1.1) https://gtsam.org/
5.- Webots Simulator (tested with version R2023a) https://cyberbotics.com/
6.- ImGui (tested with version v1.92.0) https://github.com/ocornut/imgui
Usage:
1.- Use colcon for compiling the project (in the root project folder):
source /opt/ros/galactic/setup.bash
colcon build --packages-select interfaces
. install/setup.bash
colcon build
colcon build
2.- After successfully compiling, launch the components using:
./launch2.sh
At this point, the following elements must be launched: (i) the Webots virtual world, (ii) Viz-viewer, (iii) a terminal displaying the state of the Webots component, and (iv) a terminal showing the following menu:
| 'q' to quit.
| 's'-> Start/Stop SLAM w-> Reset Control-SLAM
| 'a'-> Start/Stop Control Plan
| '-'-> zoom out '+' -> zoom in '1'-> x-y view '2' -> x-z view '3'->y-z view
| '8'-> view up '5' -> view down '4'-> view left '6' -> view right '7'-> clear plot
| '9'-> save screenshot '0' -> log statistics
| 't'-> TakeOff / landing
| r (forward) i (up)
| d (left) g(right) j(turn L) l (turn R)
| f (back) k(down)
3.- In the last terminal, press the "a" key to start the control plan (the control plan can be modified in the control_plan.txt file).
Notes: The system parameters can be modified in the configuration file /config/quad_params.yaml to adjust the method's results and performance.