On-board velocity estimation and closed-loop control of a quadrotor UAV based on optical flow

Grabe, Volker; Bülthoff, Heinrich H.; Giordano, Paolo Robuffo

doi:10.1109/icra.2012.6225328

Cited by 77 publications

(58 citation statements)

References 17 publications

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“…Part of the work presented in this paper is based on [19]- [21]. In this paper, we nevertheless provide a more comprehensive overview with additional details and several extensions.…”

Section: A Summary Of Contributionsmentioning

confidence: 99%

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Nonlinear ego-motion estimation from optical flow for online control of a quadrotor UAV

Grabe

Bülthoff

Scaramuzza

et al. 2015

The International Journal of Robotics Research

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Abstract-For the control of Unmanned Aerial Vehicles (UAVs) in GPS-denied environments, cameras have been widely exploited as main sensory modality for addressing the UAV state estimation problem. However, the use of visual information for ego-motion estimation presents several theoretical and practical difficulties, such as data association, occlusions, and lack of direct metric information when exploiting monocular cameras. In this paper, we address these issues by considering a quadrotor UAV equipped with an onboard monocular camera and an Inertial Measurement Unit (IMU). First, we propose a robust ego-motion estimation algorithm for recovering the UAV scaled linear velocity and angular velocity from optical flow by exploiting the so-called continuous homography constraint in presence of planar scenes. Then, we address the problem of retrieving the (unknown) metric scale by fusing the visual information with measurements from the onboard IMU. To this end, two different estimation strategies are proposed and critically compared: a first one exploiting the classical Extended Kalman Filter (EKF) formulation, and a second one based on a novel nonlinear estimation framework. The main advantage of the latter scheme lies in the possibility of imposing a desired transient response to the estimation error when the camera moves with a constant acceleration norm w.r.t. the observed plane. We indeed show that, when compared against the EKF on the same trajectory and sensory data, the nonlinear scheme yields considerably superior performance in terms of convergence rate and predictability of the estimation. The paper is then concluded by an extensive experimental validation, including an onboard closed-loop control of a real quadrotor UAV meant to demonstrate the robustness of our approach in real-world conditions.

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“…Part of the work presented in this paper is based on [19]- [21]. In this paper, we nevertheless provide a more comprehensive overview with additional details and several extensions.…”

Section: A Summary Of Contributionsmentioning

confidence: 99%

“…In the following we summarize, for the reader's convenience, the main features of the employed ego-motion estimation method whose full details can be found in [19], [20].…”

Section: Ego-motion Estimation From Optical Flowmentioning

confidence: 99%

Nonlinear ego-motion estimation from optical flow for online control of a quadrotor UAV

Grabe

Bülthoff

Scaramuzza

et al. 2015

The International Journal of Robotics Research

Self Cite

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“…We further used an external optical tracking system 7 in order to only retrieve the quadrotor body-frame velocity since, again, no additional global position measurements were needed. This velocity information could also be obtained exploiting vision/optical flow [47] or range finders.…”

Section: Experimental Testbedmentioning

confidence: 99%

Modeling and Control of UAV Bearing Formations with Bilateral High-level Steering

Franchi

Masone

Grabe

et al. 2012

The International Journal of Robotics Research

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Abstract-In this paper we address the problem of controlling the motion of a group of UAVs bound to keep a formation defined in terms of only relative angles (i.e., a bearing-formation). This problem can naturally arise within the context of several multi-robot applications such as, e.g., exploration, coverage, and surveillance. First, we introduce and thoroughly analyze the concept and properties of bearing-formations, and provide a class of minimally linear sets of bearings sufficient to uniquely define such formations. We then propose a bearing-only formation controller requiring only bearing measurements, converging almost globally, and maintaining bounded inter-agent distances despite the lack of direct metric information.The controller still leaves the possibility to impose group motions tangent to the current bearing-formation. These can be either autonomously chosen by the robots because of any additional task (e.g., exploration), or exploited by an assisting human co-operator. For this latter 'human-in-the-loop' case, we propose a multi-master/multi-slave bilateral shared control system providing the co-operator with some suitable force cues informative of the UAV performance. The proposed theoretical framework is extensively validated by means of simulations and experiments with quadrotor UAVs equipped with onboard cameras. Practical limitations, e.g., limited field-of-view, are also considered.

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“…El algoritmo de procesamiento de imágenes se implementó haciendo uso de las librerías de OpenCV [13]. En primer lugar se realiza un algoritmo filtrado basado en color para conservar solamente los pixeles similares al color del patrón (en este caso círculos de color rojo), posteriormente se elimina el ruido con un filtro Gaussiano y se aplica la transformada de Hough [14] para la detección del patrón (Fig.…”

Section: Detección Y Localización De Los Patronesunclassified

Sistema de inspección y vigilancia utilizando un robot aéreo guiado mediante visión artificial

Bohórquez¹,

Mendoza²,

Cortés³

2014

Iteckne

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Resumen-Este artículo presenta el desarrollo de un sistema de inspección y vigilancia el cual procesa las imágenes de las cámaras abordo con el fin de realizar una navegación autónoma o semiautónoma, según como el usuario lo especifique. El dispositivo aéreo utilizado es un cuadrotor, al que se le implementaron varias estrategias de control servo-visual para determinar la orientación, la posición del mismo y así seguir una trayectoria demarcada. Las imágenes de la segunda cámara del robot aéreo son transmitidas por la red permitiendo la inspección remota del lugar que se desea confrontar. Se realizaron las verificaciones correspondientes a los controladores, demostrando que el robot aéreo sigue diversos tipos de trayectorias satisfactoriamente. Palabras clave-Autónomo, inspección, navegación, robot aéreo, visiónAbstract-This paper presents the development of an inspection system and monitoring which processes the onboard camera images in order to perform an autonomous or semi-autonomous navigation, depending on how the user specified. The aerial device used is a quadrotor, which is implemented several strategies servovisual control to determine the orientation, the position thereof and thus follow a path demarcated. The images of the second aerial robot camera are transmitted over the network allowing remote inspection of the place you want to confront. Checks were made corresponding to the controllers, showing that the robot follows diverse types of air paths satisfactorily.

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On-board velocity estimation and closed-loop control of a quadrotor UAV based on optical flow

Cited by 77 publications

References 17 publications

Nonlinear ego-motion estimation from optical flow for online control of a quadrotor UAV

Nonlinear ego-motion estimation from optical flow for online control of a quadrotor UAV

Modeling and Control of UAV Bearing Formations with Bilateral High-level Steering

Sistema de inspección y vigilancia utilizando un robot aéreo guiado mediante visión artificial

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