scholarly journals A K Nearest Neighborhood-Based Wind Estimation for Rotary-Wing VTOL UAVs

Drones ◽  
2019 ◽  
Vol 3 (2) ◽  
pp. 31 ◽  
Author(s):  
Liyang Wang ◽  
Gaurav Misra ◽  
Xiaoli Bai

Wind speed estimation for rotary-wing vertical take-off and landing (VTOL) UAVs is challenging due to the low accuracy of airspeed sensors, which can be severely affected by the rotor’s down-wash effect. Unlike traditional aerodynamic modeling solutions, in this paper, we present a K Nearest Neighborhood learning-based method which does not require the details of the aerodynamic information. The proposed method includes two stages: an off-line training stage and an on-line wind estimation stage. Only flight data is used for the on-line estimation stage, without direct airspeed measurements. We use Parrot AR.Drone as the testing quadrotor, and a commercial fan is used to generate wind disturbance. Experimental results demonstrate the accuracy and robustness of the developed wind estimation algorithms under hovering conditions.

2019 ◽  
Vol 124 ◽  
pp. 05002
Author(s):  
A M-N Alzakkar ◽  
I.M. Valeev ◽  
N.P. Mestnikov ◽  
E.G. Nurullin

In the present work, the electric voltage stability at Muharda station in Syria was studied during the normal and up to normal loading states. The results were obtained using artificial neural network, which consists of three layers (input-hidden-output). This network is characterized by the speed and accuracy in processing before failure and supply turn-off, which may lead to economical problems. This study was carried out using two different generating schemes in this station (single double). The performance of this network consists of two stages: training stage (off-line) and testing stage (on-line), and a comparison between these stages is carried out, which leads to optimization the load in testing cases depending on the training data.


Author(s):  
Claudia Ruiz-Mercado ◽  
Arturo Pacheco-Vega ◽  
Kevin Peters

We develop a fuzzy rule based controller to perform on-line temperature control of a concentric-tubes heat exchanger facility. The rules were derived from dynamical values of the mass flow rates and fluid temperatures in the heat exchanger. The controller was embedded in a closed-loop single-input single-output system to control the outlet temperature of the cold fluid. The controller was constructed in two stages, the difference between them being the amount of information provided to the controller. To validate the fuzzy controller two sets of tests were carried out for maintaining a constant value of the outlet temperature under different perturbations. Results from this analysis demonstrate that the fuzzy-based controller is able to achieve control of the system, and that the information about the system provided to it is important in terms of accuracy and efficiency.


Author(s):  
Tiantian Liu ◽  
Shiyang Bai ◽  
Bin Tu ◽  
Minxin Chen ◽  
Benzhuo Lu

AbstractWe present a method of constructing the volume meshes of the membrane-channel protein system for finite element simulation of ion channels. The membrane channel system consists of the solvent region and the membrane-protein region. Our method focuses on labeling the tetrahedra in the solvent and membrane-protein regions and collecting the interface triangles between different regions. It contains two stages. Firstly, a volume mesh conforming the surface of the channel protein is generated by the surface and volume mesh generation tools: TMSmesh and TetGen. Then a walk-and-detect algorithm is used to identify the pore region to embed the membrane correctly. This method is shown to be robust because of its independence of the pore structure of the ion channels. In addition, we can also get the information of whether the ion channel is open or closed by the walk-and-detect algorithm. An on-line meshing procedure will be available at our website www.continuummodel.org.


1987 ◽  
Vol 109 (2) ◽  
pp. 88-96 ◽  
Author(s):  
S. Singh ◽  
M. C. Leu

The problem of optimal control of robotic manipulators is dealt with in two stages: (1) optimal trajectory planning, which is performed off-line and results in the prescription of the position and velocity of each link as a function of time along a “given” path and (2) on-line trajectory tracking, during which the manipulator is guided along the planned trajectory using a feedback control algorithm. In order to obtain a general trajectory planning algorithm which could account for various constraints and performance indices, the technique of dynamic programming is adopted. It is shown that for a given path, this problem is reduced to a search over the velocity of one moving manipulator link. The design of the algorithm for optimal trajectory planning and the relevant computational issues are discussed. Simulations are performed to test the effectiveness of this method. The use of this algorithm in conjunction with an on-line controller is also presented.


2014 ◽  
Vol 26 (5) ◽  
pp. 395-411
Author(s):  
Liu Jiongzhou ◽  
Li Jituo ◽  
Lu Guodong

Purpose – The 3D dynamic clothing simulation is widely used in computer-added garment design. Collision detection and response are the essential component and also the efficiency bottleneck in the simulation. The purpose of this paper is to propose a high efficient collision detection algorithm for 3D clothing-human dynamic simulation to achieve both real-time and virtually real simulation effects. Design/methodology/approach – The authors approach utilizes the offline data learning results to simplify the online collision detection complexity. The approach includes two stages. In the off-line stage, model triangles with most similar deformations are first, partitioned into several near-rigid-clusters. Clusters from the clothing model and the human model are matched as pairs according to the fact that they hold the potential to intersect. For each cluster, a hierarchical bounding box tree is then constructed. In the on-line stage, collision detection is checked and treated parallelly inside each cluster pairs. A multiple task allocation strategy is proposed in parallel computation to ensure efficiency. Findings – Reasonably partitioning the 3D clothing and human model surfaces into several clusters and implementing collision detection on these cluster pairs can efficiently reduce the model primitive amounts that need be detected, consequently both improving the detection efficiency and remaining the simulation virtual effect. Originality/value – The current methods only utilize the dynamic clothing-human status; the authors algorithm furthermore combines the intrinsic correspondence relationship between clothing and human clusters to efficiently shrink the detection query scope to accelerate the detection speed. Moreover, partitioning the model into several independent clusters as detection units is much more profitable for parallel computation than current methods those treat the model entirety as the unit.


1973 ◽  
Vol 2 (4) ◽  
pp. 195-197
Author(s):  
J. V. Wall

Observations for the Parkes 2700 MHz catalogue are carried out in two stages: (i), a relatively fast finding survey, followed by (ii), accurate measurement (at 2700 MHz) of flux densities and positions of the sources on the survey scans. For the first six parts of the catalogue intervals of several weeks between the stages resulted from the necessity to reduce the (analogue) survey scans manually. This communication describes a computer program which records and reduces these scans, and which produces an on-line map and source listing for the survey region. Thus the measurements of the second stage may be carried out immediately after the survey; additional advantages provided by the technique are discussed later in the paper.


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