Guillaume Sanahuja

Quad Rotorcraft Switching Control: An Application for the Task of Path Following

This paper addresses the problem of road following using a quad rotorcraft equipped with an onboard image processing system. The main objective consists of estimating and tracking the road without a priori knowledge of the path to be tracked. Special interest is also given to the development of efficient estimation and control strategies for dealing with situations when the road is not detected in the camera image. Aiming at this goal, two operational regions are defined: one for the case when the road is detected and another for the case when it is not. A switching between the measurements of imaging and inertial sensors enables estimation of the required vehicle parameters in both operational regions. In addition, for dealing with both aforementioned cases, a switching control strategy for stabilizing the vehicle lateral position is proposed. The system stability is verified not only in the two operational regions, but also in the switching boundaries between them. The performance of the switching estimation and control strategies is tested in numerical simulations and real-time experiments, successfully validating the effectiveness of the proposed approaches.

Optical flow-based controller for reactive and relative navigation dedicated to a four rotor rotorcraft

Autonomous navigation of an unmanned aerial vehicle (UAV) can be achieved with a reactive system which allows the robot to overcome all the unexpected changes in its environment. In this article, we propose a new approach to avoid frontal obstacles using known properties of the optical flow and by taking advantage of the capability of stationary flight of the rotorcraft. A state machine is proposed as a solution to equip the UAV with all reactions necessary for indoor navigation. We show how smooth transitions can be achieved by decreasing the speed of the vehicle proportional to the distance to an obstacle and by brief instants of hovering flight. Each stage of our algorithm has been tested in a mobile robot.

Finite-time observer-based output-feedback control for the global stabilisation of the PVTOL aircraft with bounded inputs

In this work, an output-feedback scheme for the global stabilisation of the planar vertical take-off and landing aircraft with bounded inputs is developed taking into account the positive nature of the thrust. The global stabilisation objective is proven to be achieved avoiding input saturation and by exclusively considering the system positions in the feedback. To cope with the lack of velocity measurements, the proposed algorithm involves a finite-time observer. The generalised versions of the involved finite-time stabilisers have not only permitted to solve the output-feedback stabilisation problem avoiding input saturation, but also provide additional flexibility in the control design that may be used in aid of performance improvements. With respect to previous approaches, the developed finite-time observer-based scheme guarantees the global stabilisation objective disregarding velocity measurements in a bounded input context. Simulation tests corroborate the analytical developments. The study includes further experimental results on an actual flying device.

Embedded robust nonlinear control for a four-rotor rotorcraft: Validation in real-time with wind disturbances

An embedded robust nonlinear controller to stabilize a four-rotor rotorcraft in presence of crosswind is developed in this paper. A previous dynamical system of the aircraft taking in account aerodynamical effects induced by lateral wind is conceived using the Newton-Euler approach. The stability analysis and robustness with respect disturbances is proved using the Lyapunov theory. Simulations have been accomplished to validate the performance of the proposed control schema. Additionally, a prototype with an embedded control system was created to prove, in real-time, the effectiveness and robustness of the proposed algorithm. Experimental results have illustrated the good behavior of the closed-loop system even in presence of several disturbances.

Test bed for applications of heterogeneous unmanned vehicles

This article addresses the development and implementation of a test bed for applications of heterogeneous unmanned vehicle systems. The test bed consists of unmanned aerial vehicles (Parrot AR.Drones versions 1 or 2, Parrot SA, Paris, France, and Bebop Drones 1.0 and 2.0, Parrot SA, Paris, France), ground vehicles (WowWee Rovio, WowWee Group Limited, Hong Kong, China), and the motion capture systems VICON and OptiTrack. Such test bed allows the user to choose between two different options of development environments, to perform aerial and ground vehicles applications. On the one hand, it is possible to select an environment based on the VICON system and LabVIEW (National Instruments) or robotics operating system platforms, which make use the Parrot AR.Drone software development kit or the Bebop_autonomy Driver to communicate with the unmanned vehicles. On the other hand, it is possible to employ a platform that uses the OptiTrack system and that allows users to develop their own applications, replacing AR.Drone’s original firmware with original code. We have developed four experimental setups to illustrate the use of the Parrot software development kit, the Bebop Driver (AutonomyLab, Simon Fraser University, British Columbia, Canada), and the original firmware replacement for performing a strategy that involves both ground and aerial vehicle tracking. Finally, in order to illustrate the effectiveness of the developed test bed for the implementation of advanced controllers, we present experimental results of the implementation of three consensus algorithms: static, adaptive, and neural network, in order to accomplish that a team of multiagents systems move together to track a target.

Micro-Helicopter for Long-Distance Missions: Description and Attitude Stabilization

This paper presents the development of a micro coaxial helicopter (MCR UAV) whose main characteristic is that it should be carried by an air shuttle transporter and then released in a desired place far away from the launching site, to develop surveillance missions in hover flight. A real-time embedded system is built in order to validate the proposed aerodynamic prototype, and a classic control law based on a classical backstepping procedure for the dynamic system is implemented to test this vehicle in autonomous flight. Finally, simulation and practical results are presented for hover flight.

Embedded Laser Vision System for Indoor Aerial Autonomous Navigation

An embedded laser vision system for indoor autonomous navigation of an Unmanned Aerial Vehicle (UAV) is presented. The vision system is composed of a camera, a classical laser line and vision algorithms and it estimates its distance and its heading with respect to a wall placed in front of the camera frame. The image processing is executed onboard and the obtained measures are sent to the microprocessor to compute the control algorithms. A flight simulator is developed in order to validate the control strategy. Additionally, flight tests are carried out in order to prove the efficiency of the closed-loop system.

Optic Flow-Based Control and Navigation of Mini Aerial Vehicles

This paper concerns recent work on the application of optic flow for control and navigation of small unmanned aerial vehicles. Bio-inspired strategies, such as the use of optic flow, have always motivated researchers in the control community. Recent methodologies for active and passive navigation of aerial vehicles using optic flow, such as obstacle detection or terrain following, are presented. Applications to path following that have been achieved at Heudiasyc Laboratory (CNRS-UTC) in Compiegne are described, in order to illustrate the strength of the concept.