scholarly journals Indoor Mapping Guidance Algorithm of Rotary-Wing UAV Including Dead-End Situations

Sensors ◽  
2019 ◽  
Vol 19 (22) ◽  
pp. 4854
Author(s):  
Jongho Park ◽  
Jaehyun Yoo
Keyword(s):  
Velocity Vector ◽  
Distance Transform ◽  
Indoor Environments ◽  
Safe Distance ◽  
Transform Method ◽  
Dead End ◽  
Data Points ◽  
Guidance Algorithm ◽  
Limited Sensing ◽  
Rotary Wing

A mapping guidance algorithm of a quadrotor for unknown indoor environments is proposed. A sensor with limited sensing range is assumed to be mounted on the quadrotor to obtain object data points. With obtained data, the quadrotor computes velocity vector and yaw commands to move around the object while maintaining a safe distance. The magnitude of the velocity vector is also controlled to prevent a collision. The distance transform method is applied to establish dead-end situation logic as well as exploration completion logic. When a dead-end situation occurs, the guidance algorithm of the quadrotor is switched to a particular maneuver. The proposed maneuver enables the quadrotor not only to escape from the dead-end situation, but also to find undiscovered area to continue mapping. Various numerical simulations are performed to verify the performance of the proposed mapping guidance algorithm.

scholarly journals Autonomous and Safe Navigation of Mobile Robots in Vineyard with Smooth Collision Avoidance

Agriculture ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 954
Author(s):  
Abhijeet Ravankar ◽  
Ankit A. Ravankar ◽  
Arpit Rawankar ◽  
Yohei Hoshino
Keyword(s):  
Mobile Robots ◽  
Real Time ◽  
Collision Avoidance ◽  
Autonomous Navigation ◽  
Autonomous Robots ◽  
Robot Navigation ◽  
Indoor Environments ◽  
Safe Distance ◽  
Field Robots ◽  
Safe Navigation

In recent years, autonomous robots have extensively been used to automate several vineyard tasks. Autonomous navigation is an indispensable component of such field robots. Autonomous and safe navigation has been well studied in indoor environments and many algorithms have been proposed. However, unlike structured indoor environments, vineyards pose special challenges for robot navigation. Particularly, safe robot navigation is crucial to avoid damaging the grapes. In this regard, we propose an algorithm that enables autonomous and safe robot navigation in vineyards. The proposed algorithm relies on data from a Lidar sensor and does not require a GPS. In addition, the proposed algorithm can avoid dynamic obstacles in the vineyard while smoothing the robot’s trajectories. The curvature of the trajectories can be controlled, keeping a safe distance from both the crop and the dynamic obstacles. We have tested the algorithm in both a simulation and with robots in an actual vineyard. The results show that the robot can safely navigate the lanes of the vineyard and smoothly avoid dynamic obstacles such as moving people without abruptly stopping or executing sharp turns. The algorithm performs in real-time and can easily be integrated into robots deployed in vineyards.

scholarly journals Monocular Vision SLAM for Indoor Aerial Vehicles

2013 ◽  
Vol 2013 ◽  
pp. 1-15 ◽  
Author(s):  
Koray Çelik ◽  
Arun K. Somani
Keyword(s):  
Indoor Navigation ◽  
Monocular Vision ◽  
Indoor Environments ◽  
Feature Points ◽  
Monocular Camera ◽  
Aerial Vehicles ◽  
Navigation Strategy ◽  
Aerial Vehicle ◽  
Technological Challenge ◽  
Limited Sensing

This paper presents a novel indoor navigation and ranging strategy via monocular camera. By exploiting the architectural orthogonality of the indoor environments, we introduce a new method to estimate range and vehicle states from a monocular camera for vision-based SLAM. The navigation strategy assumes an indoor or indoor-like manmade environment whose layout is previously unknown, GPS-denied, representable via energy based feature points, and straight architectural lines. We experimentally validate the proposed algorithms on a fully self-contained microaerial vehicle (MAV) with sophisticated on-board image processing and SLAM capabilities. Building and enabling such a small aerial vehicle to fly in tight corridors is a significant technological challenge, especially in the absence of GPS signals and with limited sensing options. Experimental results show that the system is only limited by the capabilities of the camera and environmental entropy.

scholarly journals Characterizing Fiber Diameter Variability in Nonwovens

1999 ◽  
Vol os-8 (1) ◽  
pp. 1558925099OS-80
Author(s):  
B. Pourdeyhemi
Keyword(s):  
Image Analysis ◽  
Fiber Orientation ◽  
Fiber Diameter ◽  
Field Analysis ◽  
Distance Transform ◽  
Simulation Methods ◽  
Direct Measure ◽  
Transform Method ◽  
Tracking Method ◽  
Flow Field Analysis

This paper reports on the application of the image analysis methods for characterizing fiber orientation in nonwovens. In our earlier work in this area, we reported on simulation methods as well as three methods (chord tracking, Fourier transform and Flow Field Analysis) for the measurement of fiber orientation. The chord tracking was found to be the method of choice when a direct measure of orientation was desired. This paper outlines the steps necessary to apply the chord tracking method to real fabrics. In order to deal with real webs, it was found necessary to develop a lighting scheme that resulted in images with sufficient contrast suitable for processing as well as to develop an appropriate thresholding method to obtain data suitable for analysis. Further, it is demonstrated that fiber diameter variation can be determined easily by using a “distance transform” method.

Pipe Route Design Using Variable Topography Distance Transforms

2005 ◽  
Author(s):  
Hlynur Kristinsson ◽  
Magnus Thor Jonsson ◽  
Fjola Jonsdottir
Keyword(s):  
Selection Process ◽  
Distance Transform ◽  
Two Phase ◽  
Transform Method ◽  
Geothermal Fluid ◽  
Route Design ◽  
Computationally Intensive ◽  
Land Surfaces ◽  
D Model ◽  
Variable Topography

In this paper the Variable Topography Distance Transform method (VTDT) is used to find optimal paths across physical landscapes for pipelines carrying a two-phase geothermal fluid. The method incorporates constraints such as obstacles, land costs, building costs, variable gradients, height, and environmental issues in the route selection process. The method is an expanded form of Distance Transform algorithms that are used in image processing. It offers a way to look at land surfaces as a slope-adjusted 2-D model rather than as a more complex and computationally intensive 3-D model. The VTDT method works with a digital representation, called a Digital Elevation Model (DEM), of the landscape in question. The method is then tested on the route design for pipelines carrying a two-phase geothermal fluid at the Hellisheidi Power Plant in Iceland, which is currently (early 2005) in the design and construction phase.

Galactic orbits of stars

1966 ◽  
Vol 25 ◽  
pp. 93-97
Author(s):  
Richard Woolley
Keyword(s):  
Globular Cluster ◽  
Potential Field ◽  
High Velocity ◽  
Velocity Vector ◽  
Variable Stars ◽  
The Sun ◽  
Proper Motions ◽  
Rr Lyrae ◽  
The Galaxy

It is now possible to determine proper motions of high-velocity objects in such a way as to obtain with some accuracy the velocity vector relevant to the Sun. If a potential field of the Galaxy is assumed, one can compute an actual orbit. A determination of the velocity of the globular clusterωCentauri has recently been completed at Greenwich, and it is found that the orbit is strongly retrograde in the Galaxy. Similar calculations may be made, though with less certainty, in the case of RR Lyrae variable stars.

point-Analysis Using the Extrapolation Method in the Analytical Electron microscope

1990 ◽  
Vol 48 (2) ◽  
pp. 430-431
Author(s):  
Zenji Horita ◽  
Ryuzo Nishimachi ◽  
Takeshi Sano ◽  
Minoru Nemoto
Keyword(s):  
Electron Microscope ◽  
Extrapolation Method ◽  
X Ray ◽  
Absorption Correction ◽  
Point Analysis ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Data Points ◽  
Identical Composition ◽  
X Ray Absorption

Absorption correction is often required in quantitative x-ray microanalysis of thin specimens using the analytical electron microscope. For such correction, it is convenient to use the extrapolation method[l] because the thickness, density and mass absorption coefficient are not necessary in the method. The characteristic x-ray intensities measured for the analysis are only requirement for the absorption correction. However, to achieve extrapolation, it is imperative to obtain data points more than two at different thicknesses in the identical composition. Thus, the method encounters difficulty in analyzing a region equivalent to beam size or the specimen with uniform thickness. The purpose of this study is to modify the method so that extrapolation becomes feasible in such limited conditions. Applicability of the new form is examined by using a standard sample and then it is applied to quantification of phases in a Ni-Al-W ternary alloy.The earlier equation for the extrapolation method was formulated based on the facts that the magnitude of x-ray absorption increases with increasing thickness and that the intensity of a characteristic x-ray exhibiting negligible absorption in the specimen is used as a measure of thickness.

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