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en:localisation_et_commande_embarquee_d_un_drone_en_utilisant_la_vision_stereoscopique [2016/04/07 17:22] – castilloen:localisation_et_commande_embarquee_d_un_drone_en_utilisant_la_vision_stereoscopique [2016/04/07 17:24] – castillo
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 Date PhD finished: November, 2011 \\ Date PhD finished: November, 2011 \\
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-__Current position__: **MdC at GIPSA Lab**\\+__Current position__: **MdC at GIPSA Lab since 2013**\\
  
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 == Abstract == == Abstract ==
  
-The present document addresses, theoretically and experimentally, the most relevant topics +Visual servoing is a control approach based on visual information. In this thesis, 
-for Unmanned Aerial Vehicles (UAVs) in autonomous and semi-autonomous navigation. +visual servoing schemes are proposed to control a quadrotor and an octarotor applied 
-According with the multidisciplinary nature of the studied problems, a wide range of +to positioning and navigation task. Concerning the quadrotor we use a hierarchical 
-techniques and theories are covered in the fields of robotics, automatic control, computer +control scheme whose inner-loop (fast dynamic) focuses on attitude dynamics, while 
-science, computer vision and embedded systems, among others.\\ +outer-loop (slow dynamics) deals with translational dynamics.\\
-  +
-As part of this thesis, two different experimental platforms were developed in order to +
-explore and evaluate various theories and techniques of interest for autonomous navigation. +
-The first prototype is a quadrotor specially designed for outdoor applications and was fully +
-developed in our lab. The second testbed is composed by a non expensive commercial +
-quadrotor kind AR. Drone, wireless connected to a ground station equipped with the Robot +
-Operating System (ROS), and specially intended to test computer vision algorithms and +
-automatic control strategies in an easy, fast and safe way.\\+
  
-In addition, this work provides an study of data fusion techniques looking to enhance +Also, a nonlinear controller based on separated saturations for a quadrotor is 
-the UAVs pose estimation provided by commonly used sensors. Two strategies are evaluated +proposed to stabilize it attitude. The linear position and velocity of the rotorcraft are 
-in particular, an Extended Kalman Filter (EKF) and a Particle Filter (PF). Both estimators +obtained by using a vision-based algorithm via a monocular caméra. The dynamic 
-are adapted for the system under consideration, taking into account noisy measurements +model of the quadrotor is presented using the Newton-Euler formalism. 
-of the UAV position, velocity and orientation. Simulations show the performance of +In other vision system, two cameras are used to estimate the translational position 
-the developed algorithms while adding noise from real GPS (Global Positioning System) +and velocity of the vehicle. Position was obtained using a frontal camera looking 
-measurements.\\+at a target placed on a wall. Quadrotor velocity was estimated using a camera pointing 
 +vertically downwards running an optical flow algorithm. Experimental tests 
 +showed that the quadrotor performed well at hover flight using the proposed vision 
 +based control system.\\
  
-Safe and accurate navigation for either autonomous trajectory tracking or haptic teleoperation +– **Quadrotor vision-based**\\
-of quadrotors is presented as well. A second order Sliding Mode (2-SM) control +
-algorithm is used to track trajectories while avoiding frontal collisions in autonomous flight. +
-The time-scale separation of the translational and rotational dynamics allows to design position +
-controllers by giving desired references in the roll and pitch angles, which is suitable +
-for quadrotors equipped with an internal attitude controller. The 2-SM control allows to +
-add robustness to the closed-loop system and attenuates the chattering effect. A Lyapunov +
-based analysis probes the system stability. Vision algorithms are employed to estimate the +
-pose of the vehicle using only a monocular SLAM (Simultaneous Localization and Mapping) +
-fused with inertial measurements. Distance to potential obstacles is detected and +
-computed using the sparse depth map from the vision algorithm. For teleoperation tests, +
-a haptic device is employed to feedback information to the pilot about possible collisions, +
-by exerting opposite forces. The proposed strategies are successfully tested in real-time +
-experiments, using a low-cost commercial quadrotor. \\+
  
-Also, conception and development of a Micro Aerial Vehicle (MAV) able to safely +The same system was used to estimate the 3D position of the quadrotor over 
-interact with human users by following them autonomously, is achieved in the present +a trajectory using vanishing points. The performance of the vision and control 
-work. Once a face is detected by means of a Haar cascade classifier, it is tracked applying +algorithms has been tested in a real application by a quadrotor tracking a line 
-a Kalman Filter (KF), and an estimation of the relative position with respect to the face +painted in a wall. Similarly the velocity estimation is obtained using an optic 
-is obtained at a high rate. A linear Proportional Derivative (PD) controller regulates the +flow algorithm. The estimated position and velocity information obtained 
-UAV’s position in order to keep a constant distance to the face, employing as well the extra +from the vision system is combined with the angular rates and displacements 
-available information from the embedded UAV’s sensors. Several experiments were carried +of the inertial measurement unit to compute the control inputs. It has been 
-out through different conditions, showing good performance even under disadvantageous +shown that the proposed control scheme achieves the tracking objective of 
-scenarios like outdoor flight, being robust against illumination changes, wind perturbations, +the visual reference.\\ 
-image noise and the presence of several faces on the same image. + 
-\\+– **Octarotor vision-based** \\ 
 + 
 +In this thesis, it is presented a visual feedback a control of an octarotor 
 +using image-based visual servoing (IBVS) with stereo vision. Autonomous 
 +control of an UAV requires a precise measurements and/or estimation of the 
 +vehicle’s pose and also the knowledge of its surrounding environment. In 
 +order to control the orientation and the position of flying robot with respect 
 +to a target, we propose to use a navigation system based on binocular vision 
 +system combined with inertial sensors. This combination of sensors, allows 
 +us to get a complete characterization of the state of aerial vehicle. In other 
 +words, using the stereo vision system we are able to estimate the UAV’s 
 +3D position, while from the inertial sensors we obtain the orientation of 
 +rotorcraft. A semi-embedded navigation system combining stereo vision with 
 +inertial information is proposed.\\ 
 + 
 +The hierarchical control approach is appropriate to stabilize the 6DOF dynamics 
 +of the quadrotor, it takes advantage of the time scale separation between rotational 
 +(fast) and translational (slow) dynamics. For this reason, despite the lower frequency 
 +rate of vision-based measurements is able to stabilize in real-time the quadrotor 
 +translational dynamics. This combination of measurement strategies has many advantages 
 +because one works very well at low speeds (vision system) and the other at 
 +high speeds (inertial sensors). Both work at different sample rate. Taking advantage 
 +of this property we have obtained a simplified dynamical model of the rotorcraft. 
 +This model is given by six independent double integrators which have been stabilized 
 +using proportional-derivative (PD) control. The real-time experiments have 
 +shown an acceptable performance of the flying machine applying the control law 
 +and sensing system proposed.\\
  
-Finally, this thesis deals with the problem of implementing a safe and fast transportation +An embedded control system for the mini rotorcraft is implemented. The control 
-system using an UAV kind quadrotor with a cable suspended load. The objective consists +is validated by experimental tests. Experimental results show that the implementation 
-in transporting the load from one place to another, in a fast way and with minimum +of the control law on an embedded control system is satisfactory for autonomous 
-swing in the cable. An Interconnection and Damping Assignment-Passivity Based Control +hovering in indoors and outdoors with light or no wind. Real time experiences are 
-(IDA-PBC) for the system of interest is successfully implemented and tested in real time +developed to validate the performance of navigation systems proposed. This work 
-experiments. The use of this control technique avoids the use of an extra sensor for the +highlights the potential of the computer vision based position control strategies for 
-swing angle measurement. An experimental platform composed by a quadrotor equipped +UAV.
-with a rigid rod with two degrees of freedom in the joint, is developed. UAV navigation is +
-achieved via monocular vision.+
  
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