A visual guided quadrotor for IMAV 2012 indoor autonomy competition and visual control of a quadrotor for the IMAV 2012 indoor dynamics competition

Scientific Conference (2012, July)

A Hierarchical Strategy for Real-Time Tracking On-Board UAVs

in ICUAS 2012 : 2012 International Conference on Unmanned Aircraft Systems (2012, June)

In this paper, we present a real-time tracking strategy based on direct methods for tracking tasks on-board UAVs, that is able to overcome problems posed by the challenging conditions of the task: e.g ... [more ▼]

In this paper, we present a real-time tracking strategy based on direct methods for tracking tasks on-board UAVs, that is able to overcome problems posed by the challenging conditions of the task: e.g. constant vibrations, fast 3D changes, and limited capacity on-board. The vast majority of approaches make use of feature-based methods to track objects. Nonetheless, in this paper we show that although some of these feature-based solutions are faster, direct methods can be more robust under fast 3D motions (fast changes in position), some changes in appearance, constant vibrations (without requiring any specific hardware or software for video stabilization), and situations where part of the object to track is out the field of view of the camera. The performance of the proposed strategy is evaluated with images from real-flight tests using different evaluation mechanisms (e.g. accurate position estimation using a Vicon sytem). Results show that our tracking strategy performs better than well known feature-based algorithms and well known configurations of direct methods, and that the recovered data is robust enough for vision-in-the-loop tasks. [less ▲]

See-and-Avoid Quadcopter using Fuzzy Control Optimized by Cross-Entropy

in See-and-Avoid Quadcopter using Fuzzy Control Optimized by Cross-Entropy (2012)

In this work we present an optimized fuzzy visual servoing system for obstacle avoidance using an unmanned aerial vehicle. The cross-entropy theory is used to optimise the gains of our controllers. The ... [more ▼]

In this work we present an optimized fuzzy visual servoing system for obstacle avoidance using an unmanned aerial vehicle. The cross-entropy theory is used to optimise the gains of our controllers. The optimization process was made using the ROS-Gazebo 3D simulation with purposeful extensions developed for our experiments. Visual servoing is achieved through an image processing front-end that uses the Camshift algorithm to detect and track objects in the scene. Experimental flight trials using a small quadrotor were performed to validate the parameters estimated from simulation. The integration of cross-entropy methods is a straightforward way to estimate optimal gains achieving excellent results when tested in real flights. [less ▲]

Adaptive Control System based on Lineal Control Theory for the Path-Following Problem of a Car-Like Mobile Robot

in IFAC Conference on Advances in PID Control PID'12 (2012)

The objective of this paper is to design a path following control system for a car-like mobile robot using classical linear control techniques, so that it adapts on-line to varying conditions during the ... [more ▼]

The objective of this paper is to design a path following control system for a car-like mobile robot using classical linear control techniques, so that it adapts on-line to varying conditions during the trajectory following task. The main advantages of the proposed control structure is that well known linear control theory can be applied in calculating the PID controllers to ful l control requirements, while at the same time it is exible to be applied in non-linear changing conditions of the path following task. For this purpose the Frenet frame kinematic model of the robot is linearised at a varying working point that is calculated as a function of the actual velocity, the path curvature and kinematic parameters of the robot, yielding a transfer function that varies during the trajectory. The proposed controller is formed by a combination of an adaptive PID and a feed-forward controller, which varies accordingly with the working conditions and compensates the non-linearity of the system. The good features and exibility of the proposed control structure have been demonstrated through realistic simulations that include both kinematics and dynamics of the car-like robot. [less ▲]

On-board and ground visual pose estimation techniques for UAV control

in Journal of Intelligent and Robotic Systems (2011), 61(1), 301--320

Aerial object following using visual fuzzy servoing

in First Workshop on Research, Development and Education on Unmanned Aerial Systems (RED-UAS 2011) (2011)

This article presents a visual servoing system to follow a 3D moving object by a Micro Unmanned Aerial Vehicle (MUAV). The presented control strategy is based only on the visual information given by an ... [more ▼]

This article presents a visual servoing system to follow a 3D moving object by a Micro Unmanned Aerial Vehicle (MUAV). The presented control strategy is based only on the visual information given by an adaptive tracking method based on the color information. A visual fuzzy system has been developed for servoing the camera situated on a rotary wing MAUV, that also considers its own dynamics. This system is focused on continuously following of an aerial moving target object, maintaining it with a fixed safe distance and centered on the image plane. The algorithm is validated on real flights on outdoors scenarios, showing the robustness of the proposed systems against winds perturbations, illumination and weather changes among others. The obtained results indicate that the proposed algorithms is suitable for complex controls task, such object following and pursuit, flying in formation, as well as their use for indoor navigation [less ▲]

Fuzzy-4D/RCS for Unmanned Aerial Vehicles

in BICS 2010 Conference on Brain-Inspired Cognitive Systems (2010, July)

Abstract This paper presents an improvement of the cognitive architecture, 4D/RCS, developed by the NIST. This improvement consist of the insertion of Fuzzy Logic cells (FLCs), in different parts and ... [more ▼]

Abstract This paper presents an improvement of the cognitive architecture, 4D/RCS, developed by the NIST. This improvement consist of the insertion of Fuzzy Logic cells (FLCs), in different parts and hierarchy levels of the architecture, and the adaptation of this architecture for Unmanned Aerial Vehicles (UAVs). This advance provides an improvement in the functionality of the system based on the uses of the Miguel Olivares’ Fuzzy Software for the definition of the FLCs and its adaptative learning algorithm. These adaptative-FLCs contribute with the reduction of the uncertainty in the data sensor adquisition, a more adaptative behavior of the system to the real world and the reduction of the computational cost in the decision making. [less ▲]

3D pose estimation based on planar object tracking for UAVs control

in Proccedings of IEEE International Conference on Robotics and Automation (ICRA) (2010)

This article presents a real time Unmanned Aerial Vehicles UAVs 3D pose estimation method using planar object tracking, in order to be used on the control system of a UAV. The method explodes the rich ... [more ▼]

This article presents a real time Unmanned Aerial Vehicles UAVs 3D pose estimation method using planar object tracking, in order to be used on the control system of a UAV. The method explodes the rich information obtained by a projective transformation of planar objects on a calibrated camera. The algorithm obtains the metric and projective components of a reference object (landmark or helipad) with respect to the UAV camera coordinate system, using a robust real time object tracking based on homographies. The algorithm is validated on real flights that compare the estimated data against that obtained by the inertial measurement unit IMU, showing that the proposed method robustly estimates the helicopter's 3D position with respect to a reference landmark, with a high quality on the position and orientation estimation when the aircraft is flying at low altitudes, a situation in which the GPS information is often inaccurate. The obtained results indicate that the proposed algorithm is suitable for complex control tasks, such as autonomous landing, accurate low altitude positioning and dropping of payloads. [less ▲]

Omnidirectional vision applied to Unmanned Aerial Vehicles (UAVs) attitude and heading estimation

in Robotics and Autonomous Systems (2010), 58(6), 809-819

This paper presents an aircraft attitude and heading estimator using catadioptric images as a principal sensor for UAV or as a redundant system for IMU (Inertial Measure Unit) and gyro sensors. First, we ... [more ▼]

This paper presents an aircraft attitude and heading estimator using catadioptric images as a principal sensor for UAV or as a redundant system for IMU (Inertial Measure Unit) and gyro sensors. First, we explain how the unified theory for central catadioptric cameras is used for attitude and heading estimation, explaining how the skyline is projected on the catadioptric image and how it is segmented and used to calculate the UAV's attitude. Then, we use appearance images to obtain a visual compass, and we calculate the relative rotation and heading of the aerial vehicle. Finally the tests and results using the UAV COLIBRI platform and the validation of them in real flights are presented, comparing the estimated data with the inertial values measured on board. (C) 2010 Elsevier B.V. All rights reserved. [less ▲]

Visual servoing using fuzzy controllers on an unmanned aerial vehicle

in EUROFUSE 2009. workshop on on preference modelling and decision analysis (2009, September)

This paper presents an implementa- tion of three Fuzzy Logic controllers working in parallel onboard a UAV, two for a pan-tilt camera platform and the third for control the yaw of the helicopter. This ... [more ▼]

This paper presents an implementa- tion of three Fuzzy Logic controllers working in parallel onboard a UAV, two for a pan-tilt camera platform and the third for control the yaw of the helicopter. This implementation uses a Lucas-Kanade tracker algo- rithm with a pyramidal optical ow implementation, which gives infor- mation to follow statics and moving objects, besides the UAV vibrations and movements. The platform con- troller is helped by the heading con- troller, in order to make smooth the big movements to the platform, re- ducing the risk of lost the warp selec- tion of the object to track. Also, the heading control remove the physic limit of the platform at the yaw axis. Some laboratory and UAV tests are presented in order to show the differ- ent behaviors and the good response of the presented controllers. [less ▲]