| High level objectives|
The objective of this project is the development of a new concept of completely autonomous flying robot equipped with monitoring sensors. In order to survey small size area or non-moving scene the flying robot must be able to perform stationary flight. In addition, it must be rapidly deployable. The project will therefore concern rotary wing unmanned aerial vehicle (UAV).This machine will be a small size VTOL (Vertical take Off and Landing) UAV designed for autonomous inspection and survey task in urban area or more generally in constrained outside environment (known and unknown environment with moving obstacles). Using the autonomy faculty of the robot, users will be able to devote their attention to the exploitation of the data coming from the mission sensors, and not on the navigation of the vector.
The heart of the project is the development of software and hardware modules for the autonomy of small size drones in term of navigation, localization and robustness to unexpected events. To reach this goal, different scientific fields will be addressed: mission planning, collision avoidance, trajectory and localization algorithms and drone hardware.
In addition to the sensors used for the flight autonomy, the drone will be able to carry specific sensors for the survey mission (Video, temperature, others …). However the research activities will not be axed on efficiency of the mission sensors, for which the technologies are already well mastered. They will instead focus on the decisional autonomy of a flying robot able to carry such sensors.
The flying robot will evolve in a constrained urban environment with human presence. For safety reasons, we will therefore demonstrate the efficiency of the decisional autonomy feature by developing an innovative an secure small size robot (it is also a more safe way to use it on crowded urban area). However, it is important to note that all the results of the project (and more specifically that relative to autonomy) will be easily adaptable to bigger VTOL or other kind of flying mobile robots.
| Technical objectives and expected results|
To reach the ultimate goal of setting up an autonomous UAV, the project is divided into different fields of research :
- Improvement of expected behaviour of a flying robot with development of perception and command strategies to add more autonomy to the flight, even in urban environment.
- Mission Control System (MCS) with intuitive MMI for mission preparation and control
- µUAV development for deployment efficiency and security
| Perception and command for autonomous drone|
* Attitude stabilization
The attitude stabilization of the UAV is performed using an inertial sensor (Gyrometer and accelerometer MEMS) to have a safe flight, even with moderated wind or aerologic perturbation.
Because the propellers generate acceleration and torques forces, it is essential to control closely the speed of each electric propeller according to the desired attitude. Wind perturbation will offset this attitude. Using inertial measurements will allow the control loop to counteract these external forces and will prevent the drone to flip over.
* Localization and navigation
The localization of the drone is performed by different sensors modalities, including Global positioning (GPS) , vision, inertial sensors. This redundancy increases the reliability of the system in case of momentary loss of information from one of the sensors. (GPS loss, bad vision feedback or too poor video contents).
The localization of the drone resulting from this sensor fusion will be shown to the user in order to supervise the mission. It will allow the drone to be autonomous, especially when it is not visible or too far from the user, and will compensate the deviation due to moderated wind or aerologic perturbations.
* Obstacle avoidance
Obstacle avoidance and track of a goal will be achieved initially in a behavior-based way, without explicit object recognition. Rather, movement alternatives generated from goal attraction and obstacle repellence will be combined in a dynamical systems approach. Obstacle detection will be based on optic flow, resulting in implicit measure of obstacle relevance (time-to-collision). This algorithm will be suitable for on-board implementation in later versions of the robot.
| Mission Control System (MCS) with intuitive MMI for mission preparation and control|
The users will use a dedicated Mission Control System (MCS) with Man Machine Interface to define the trajectory that the drone will follow autonomously and the target areas to focus on.
This MMI is the main link between the drone system and the user. This MMI will :
-- display a map of the area to explore as a 2D or 3D view of the environment. It may be connected to a Geographical Information System.
-- enable the user to define trajectories with sequences of waypoints which will be followed by the drone on request. It may provide automatic waypoints based on the geographic map.
-- enable the user at any time to switch between different control modes : autonomous navigation on one of the defined trajectories, manual control, standby and other modes if necessary
-- display the estimated position of the drone and the data coming from the mission sensors (video, IR, …) and the estimated battery autonomy.
| µUAV development for deployment efficiency and security|
Concerning the mechanical design of the drone, the consortium will work on a well known mechanical structure allowing stationary flight: the X4-flyer. It is made of four electric propellers at the end of a X structure. If the two-propeller helicopter is the most famous VTOL vehicle, the main advantages of this design are to offer a very simply mechanical structure, very robust and low cost, with a dynamic model easy to identify.
The drone will have a small size (less than 50 cm of diameter) and short weight (less than 1 kg) in order to be easily deployed and to be as safe as possible for people inside the survey area.
A study will be done to design the propeller group (blade / motor) taking into account the useful payload of the drone and its energetic autonomy. A careenage will include the entire machine in order to forbid the access to the moving part (blades) for the security of users and people around. This careenage will be also designed to reduce the effects of aerologic perturbations.
Finally this careenage will also protect the drone against shocks at low speed in order to rebound on undetected (or non avoided) obstacles, without breaking the blades or the entire machine and continue the mission.