scholarly journals Distance and velocity estimation using optical flow from a monocular camera

2017 ◽  
Vol 9 (3) ◽  
pp. 198-208 ◽  
Author(s):  
Hann Woei Ho ◽  
Guido CHE de Croon ◽  
Qiping Chu
Keyword(s):  
Optical Flow ◽  
Micro Air Vehicles ◽  
Velocity Estimation ◽  
Flight Tests ◽  
Monocular Camera ◽  
Flying Insects ◽  
Outdoor Environments ◽  
Landing Control ◽  
Vehicle Movement ◽  
Air Vehicles

Monocular vision is increasingly used in micro air vehicles for navigation. In particular, optical flow, inspired by flying insects, is used to perceive vehicle movement with respect to the surroundings or sense changes in the environment. However, optical flow does not directly provide us the distance to an object or velocity, but the ratio of them. Thus, using optical flow in control involves nonlinearity problems which add complexity to the controller. To deal with that, we propose an algorithm that estimates distance and velocity of the vehicle based on optical flow measured from a monocular camera and the knowledge of control inputs. This algorithm applies an extended Kalman filter to state estimation and uses the estimates for landing control. We implement and test our algorithm in computer simulation and on board a Parrot AR.Drone 2.0 to demonstrate its feasibility for micro air vehicles landings. Results of the simulation and multiple flight tests show that the algorithm is able to estimate height and velocity of the micro air vehicles accurately, and achieves smooth landings with these estimates, even in windy outdoor environments.

scholarly journals Insect-like flapping wing mechanism based on a double spherical Scotch yoke

2005 ◽  
Vol 2 (3) ◽  
pp. 223-235 ◽  
Author(s):  
Cezary Galiński ◽  
Rafał Żbikowski
Keyword(s):  
Insect Flight ◽  
Micro Air Vehicles ◽  
Flapping Wing ◽  
Controlled Study ◽  
Concept Design ◽  
Test Bed ◽  
Insect Wing ◽  
Flying Insects ◽  
Adjustable Mechanism ◽  
Air Vehicles

We describe the rationale, concept, design and implementation of a fixed-motion (non-adjustable) mechanism for insect-like flapping wing micro air vehicles in hover, inspired by two-winged flies (Diptera). This spatial (as opposed to planar) mechanism is based on the novel idea of a double spherical Scotch yoke. The mechanism was constructed for two main purposes: (i) as a test bed for aeromechanical research on hover in flapping flight, and (ii) as a precursor design for a future flapping wing micro air vehicle. Insects fly by oscillating (plunging) and rotating (pitching) their wings through large angles, while sweeping them forwards and backwards. During this motion the wing tip approximately traces a ‘figure-of-eight’ or a ‘banana’ and the wing changes the angle of attack (pitching) significantly. The kinematic and aerodynamic data from free-flying insects are sparse and uncertain, and it is not clear what aerodynamic consequences different wing motions have. Since acquiring the necessary kinematic and dynamic data from biological experiments remains a challenge, a synthetic, controlled study of insect-like flapping is not only of engineering value, but also of biological relevance. Micro air vehicles are defined as flying vehicles approximately 150 mm in size (hand-held), weighing 50–100 g, and are developed to reconnoitre in confined spaces (inside buildings, tunnels, etc.). For this application, insect-like flapping wings are an attractive solution and hence the need to realize the functionality of insect flight by engineering means. Since the semi-span of the insect wing is constant, the kinematics are spatial; in fact, an approximate figure-of-eight/banana is traced on a sphere. Hence a natural mechanism implementing such kinematics should be (i) spherical and (ii) generate mathematically convenient curves expressing the figure-of-eight/banana shape. The double spherical Scotch yoke design has property (i) by definition and achieves (ii) by tracing spherical Lissajous curves.

scholarly journals Vertical landing for micro air vehicles using event-based optical flow

2017 ◽  
Vol 35 (1) ◽  
pp. 69-90 ◽  
Author(s):  
Bas J. Pijnacker Hordijk ◽  
Kirk Y. W. Scheper ◽  
Guido C. H. E. de Croon
Keyword(s):  
Optical Flow ◽  
Micro Air Vehicles ◽  
Vertical Landing ◽  
Event Based ◽  
Air Vehicles

scholarly journals A Velocity Estimation Technique for a Monocular Camera Using mmWave FMCW Radars

Electronics ◽  
2021 ◽  
Vol 10 (19) ◽  
pp. 2397
Author(s):  
Aarav Pandya ◽  
Ajit Jha ◽  
Linga Reddy Cenkeramaddi
Keyword(s):  
Optical Flow ◽  
Autonomous Agents ◽  
Feature Fusion ◽  
Target Object ◽  
Velocity Estimation ◽  
Machine Learning Techniques ◽  
Design Data ◽  
Monocular Camera ◽  
Dynamic Estimation ◽  
Radar Calibration

Perception in terms of object detection, classification, and dynamic estimation (position and velocity) are fundamental functionalities that autonomous agents (unmanned ground vehicles, unmanned aerial vehicles, or robots) have to navigate safely and autonomously. To date, various sensors have been used individually or in combination to achieve this goal. In this paper, we present a novel method for leveraging millimeter wave radar’s (mmW radar’s) ability to accurately measure position and velocity in order to improve and optimize velocity estimation using a monocular camera (using optical flow) and machine learning techniques. The proposed method eliminates ambiguity in optical flow velocity estimation when the object of interest is at the edge of the frame or far away from the camera without requiring camera–radar calibration. Moreover, algorithms of various complexity were implemented using custom dataset, and each of them successfully detected the object and estimated its velocity accurately and independently of the object’s distance and location in frame. Here, we present a complete implementation of camera–mmW radar late feature fusion to improve the camera’s velocity estimation performance. It includes setup design, data acquisition, dataset development, and finally, implementing a lightweight ML model that successfully maps the mmW radar features to the camera, allowing it to perceive and estimate the dynamics of a target object without any calibration.

scholarly journals Micro air vehicle local pose estimation with a two-dimensional laser scanner: A case study for electric tower inspection

2017 ◽  
Vol 10 (2) ◽  
pp. 127-156
Author(s):  
Carlos Viña ◽  
Pascal Morin
Keyword(s):  
Inertial Measurement Unit ◽  
Position Control ◽  
Micro Air Vehicles ◽  
Indoor Navigation ◽  
Velocity Estimation ◽  
Measurement Unit ◽  
Two Dimensional ◽  
Inertial Measurement ◽  
Inspection Tasks ◽  
Air Vehicles

Automation of inspection tasks is crucial for the development of the power industry, where micro air vehicles have shown a great potential. Self-localization in this context remains a key issue and is the main subject of this work. This article presents a methodology to obtain complete three-dimensional local pose estimates in electric tower inspection tasks with micro air vehicles, using an on-board sensor set-up consisting of a two-dimensional light detection and ranging, a barometer sensor and an inertial measurement unit. First, we present a method to track the tower’s cross-sections in the laser scans and give insights on how this can be used to model electric towers. Then, we show how the popular iterative closest point algorithm, that is typically limited to indoor navigation, can be adapted to this scenario and propose two different implementations to retrieve pose information. This is complemented with attitude estimates from the inertial measurement unit measurements, based on a gain-scheduled non-linear observer formulation. An altitude observer to compensate for barometer drift is also presented. Finally, we address velocity estimation with views to feedback position control. Validations based on simulations and experimental data are presented.

Inertial Optical Flow for Throw-and-Go Micro Air Vehicles

2015 ◽  
Author(s):  
Stephan Weiss ◽  
Roland Brockers ◽  
Sigurd Albrektsen ◽  
Larry Matthies
Keyword(s):  
Optical Flow ◽  
Micro Air Vehicles ◽  
Air Vehicles

Use of MEMS For Micro Air Vehicles

2000 ◽  
Author(s):  
Bruce Carroll ◽  
Norman Fitz-Coy ◽  
Wel Shyy ◽  
Toshikazu Nishida
Keyword(s):  
Micro Air Vehicles ◽  
Air Vehicles
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