scholarly journals Analysis of the Impact of the Target Illumination Time on the Effectiveness of the Flight Trajectory Correction System

2019 ◽  
Vol 49 (1) ◽  
pp. 229-253
Author(s):  
Grzegorz Kowaleczko ◽  
Mariusz Pietraszek ◽  
Łukasz Słonkiewicz
Keyword(s):  
Degrees Of Freedom ◽  
Flight Trajectory ◽  
Control Laws ◽  
Illumination Time ◽  
Six Degrees Of Freedom ◽  
Laser Sensors ◽  
Main Factors ◽  
The Impact ◽  
Flight Simulations ◽  
Correction System

Abstract This paper presents method of flight simulations for released laser guided bomb. Calculations were performed using six-degrees-of-freedom mathematical model of a bomb motion. Aerodynamics of the bomb was calculated using commercial software. Control laws were determined on the basis of signals detected by two pairs of laser sensors. Exemplary results of numerical calculations are submitted and conclusions focused on the main factors influencing on bombing accuracy are shown.

scholarly journals Near-Field Measurement of Six Degrees of Freedom Mining-Induced Tremors in Lower Silesian Copper Basin

Sensors ◽  
2020 ◽  
Vol 20 (23) ◽  
pp. 6801
Author(s):  
Krzysztof Fuławka ◽  
Witold Pytel ◽  
Bogumiła Pałac-Walko
Keyword(s):  
Seismic Wave ◽  
Degrees Of Freedom ◽  
Seismic Waves ◽  
Near Field ◽  
High Energy ◽  
Rotational Component ◽  
Empirical Formulas ◽  
Six Degrees Of Freedom ◽  
The Impact

The impact of seismicity on structures is one of the key problems of civil engineering. According to recent knowledge, the reliable analysis should be based on both rotational and translational components of the seismic wave. To determine the six degrees of freedom (6-DoF) characteristic of mining-induced seismicity, two sets of seismic posts were installed in the Lower Silesian Copper Basin, Poland. Long-term continuous 6-DoF measurements were conducted with the use of the R-1 rotational seismometer and EP-300 translational seismometer. In result data collection, the waveforms generated by 39 high-energy seismic events were recorded. The characteristic of the rotational component of the seismic waves were described in terms of their amplitude and frequency characteristics and were compared with translational measurements. The analysis indicated that the characteristic of the rotational component of the seismic wave differs significantly in comparison to translational ones, both in terms of their amplitude and frequency distribution. Also, attenuation of rotational and translational components was qualitatively compared. Finally, the empirical formulas for seismic rotation prediction in the Lower Silesian Copper Basin were developed and validated.

Experiments on Linear and Nonlinear Control of a Multi-DOF Parallel Mechanism

2003 ◽  
Author(s):  
Sandor Riebe ◽  
Heinz Ulbrich
Keyword(s):  
Degrees Of Freedom ◽  
Motion Tracking ◽  
Parallel Robot ◽  
Parallel Kinematics ◽  
Control Laws ◽  
Six Degrees Of Freedom ◽  
Position Accuracy ◽  
Nonlinear Approach ◽  
Linear Approach ◽  
Measurement Results

Parallel kinematics with multi degrees-of-freedom (DOF), like hexapod-systems, are mostly used in applications where high demands on position accuracy are required and/or high accelerations are needed. Adequate control concepts are essential in order to achieve the desired dynamic response. This paper deals with a comparative study of two structural different control concepts applied on a parallel robot with six degrees-of-freedom. The first one is a decentral linear approach and the second one is a multivariable nonlinear approach. The two concepts are presented and implemented on an experimental hexapod-system. In order to verify the used dynamic model comparisons between simulation and measurement results are shown. Finally, experiments have been carried out to compare the control laws with respect to their motion tracking performance.

Trajectory Tracking of 3D Autonomous Vehicles Using Backstepping Control

2019 ◽  
Author(s):  
Karl Ludwig Fetzer ◽  
Sergey G. Nersesov ◽  
Hashem Ashrafiuon
Keyword(s):  
Autonomous Vehicles ◽  
Degrees Of Freedom ◽  
3D Model ◽  
Autonomous Vehicle ◽  
Backstepping Control ◽  
Reference Trajectory ◽  
Control Laws ◽  
Six Degrees Of Freedom ◽  
Error Dynamics ◽  
Dynamics Stability

Abstract In this paper, the authors derive backstepping control laws for tracking a time-based reference trajectory for a 3D model of an autonomous vehicle with two degrees of underactuation. Tracking all six degrees of freedom is made possible by a transformation that reduces the order of the error dynamics. Stability of the resulting error dynamics is proven and demonstrated in simulations.

Numerical Simulation of Ship-Ship Interactions in Waves

2019 ◽  
Author(s):  
Xueshen Xie ◽  
Yuxiang Wan ◽  
Qing Wang ◽  
Hao Liu ◽  
Dakui Feng
Keyword(s):  
Numerical Simulation ◽  
Degrees Of Freedom ◽  
Simulation Analysis ◽  
Turbulence Models ◽  
Body Motion ◽  
Structured Grid ◽  
Six Degrees Of Freedom ◽  
Unsteady Rans ◽  
Small Ship ◽  
The Impact

Abstract A numerical simulation of the hydrodynamic interaction and attitude of a ship and two ships of different sizes navigating in parallel in waves were carried out in this paper. The study of the two ships navigating in parallel is of great significance in marine replenishment. This paper used in house computational fluid dynamics (CFD) code to solve unsteady RANS equation coupled with six degrees of freedom (6DOF) solid body motion equations. URANS equations are solved by finite difference method and PISO algorithm. Structured grid with overset technology have been used to make computations. Turbulence models used the Shear Stress Transport (SST) k-ω model. The method used for free surface simulation is single phase level set. In this paper, two DTMB 5415 with different scales are selected for simulation analysis. This paper analyzed the impact of the big ship on the small ship when the two ships were navigating in parallel. This paper also analyzed the relationship between interaction and velocity between hulls, which has certain guiding significance for the ship’s encounter on the sea.

Coupling in-flight trajectory planning and flocking for multiple autonomous parafoils

2012 ◽  
Vol 226 (6) ◽  
pp. 691-720 ◽  
Author(s):  
A Rosich ◽  
P Gurfil
Keyword(s):  
Global Positioning System ◽  
Autonomous Navigation ◽  
Degrees Of Freedom ◽  
Reference Trajectory ◽  
Flight Trajectory ◽  
Multiagent Simulation ◽  
Six Degrees Of Freedom ◽  
Wide Range ◽  
Global Positioning ◽  
Simple Rules

Much effort has been invested during the past decades in design of parafoils for a wide range of payloads and in development of means for their guidance. Existing parafoils are capable of autonomous navigation using the global positioning system and other onboard sensors. The purpose of this study is to explore the advantages of coordination among multiple autonomous parafoils. Each parafoil is able to navigate to the target on its own by following a real-time-generated reference trajectory. A new method for trajectory generation is presented and behaviour-based rules are developed that control the relative motion of the descending parafoils. The set of simple rules results in an emergent behaviour known as flocking. The coupling between trajectory following and flocking is studied in a multiagent simulation. The simulation uses a realistic six-degrees-of-freedom model of a heavy cargo parafoil. The obtained results demonstrate the possibility of flocking behaviour for guided parafoils. The flocking rules ensure safe separation between the vehicles headed for the same target and allow the parafoils to follow a reference trajectory as a group.

scholarly journals Study of soccer ball flight trajectory

2018 ◽  
Vol 145 ◽  
pp. 01002 ◽  
Author(s):  
Juliana Javorova ◽  
Anastas Ivanov
Keyword(s):  
Differential Equations ◽  
Degrees Of Freedom ◽  
Spherical Body ◽  
Flight Trajectory ◽  
Aerodynamic Forces ◽  
Soccer Ball ◽  
Six Degrees Of Freedom ◽  
Football Game ◽  
Ball Flight ◽  
General Motion

In this paper the trajectories of a soccer ball for the most important kicks in the football game - a corner kick and a direct free kick are studied. The soccer ball is modelled as an ideal rigid hollow spherical body with six degrees of freedom, which performs a general motion in an immovable air environment with constant parameters. The ball 3D orientation is determined by the three Cardan angles. The aerodynamic forces and moments with which the air environment acts to the ball are taken into account. Two of the most dangerous areas of the football goal are defined. Differential equations which describe the motion of the soccer ball are solved numerically by MatLab-Simulink.

Control Laws synthesis of multi-arm cooperating robots with elastic interconnection at the contacts

Robotica ◽  
2000 ◽  
Vol 18 (2) ◽  
pp. 183-193 ◽  
Author(s):  
Milovan Zˇivanović ◽  
Miomir Vukobratović
Keyword(s):  
Theoretical Analysis ◽  
Degrees Of Freedom ◽  
Closed Loop ◽  
Cooperative System ◽  
Controlled System ◽  
Control Laws ◽  
Cooperative Manipulation ◽  
Six Degrees Of Freedom ◽  
Cooperating Robots

The problem of the control of the object cooperative manipulation during the work of multiple non-redundant six degrees-of-freedom manipulators is considered in this paper. The problem of the cooperative manipulation control is, like all its problems, solvable only if the system is considered as the elastic one, taking into account all existing constraints. The controlled system is with the output number greater than the available number of inputs, therefore, in the first stage the desired motions are selected from the set of the possible nominal ones, containing the trajectories of the manipulated object mass centre and slave manipulators contacts. Afterward, the classification of control tasks is performed. The procedure for the calculation of the driving torques introduced into the joints of the manipulators, necessary to obtain the nominal trajectory tracking, is proposed. The theoretical analysis of cooperative system closed loop behaviour is exposed, particular attention being paid to the uncontrolled variables. The procedure is illustrated on the example of the simple closed loop cooperative system, consisting of the manipulated object and two one degree-of-freedom manipulators. For this system, the behaviour is determined and the driving torques are calculated.

scholarly journals Image Processing Techniques to Improve Deep 6DoF Detection in RGB Images

2019 ◽  
Author(s):  
Heitor Felix ◽  
Francisco Simões ◽  
Kelvin Cunha ◽  
Veronica Teichrieb
Keyword(s):  
Object Detection ◽  
Degrees Of Freedom ◽  
Single Channel ◽  
Local Binary Patterns ◽  
Six Degrees Of Freedom ◽  
Learning Techniques ◽  
Great Relevance ◽  
Art Research ◽  
Processing Techniques ◽  
The Impact

Six degrees of freedom (6DoF) Object Detection has great relevance in computer vision due to its use in applications on several areas, such as augmented reality and robotics. Even with the improved results provided by deep learning techniques, object detection of textured and non-textured objects is still a challenge. The objective of this work was to seek improvements in the six degrees of freedom detection of non-textured objects using a Convolutional Neural Network (CNN) approach through the preprocessing of the images that were used for training the network. A State of the art research was carried out on techniques that use CNN to detect objects in six degrees of freedom. We also searched for filters with enhancement factors for detection. Finally, a detection technique based on a CNN was selected and adapted to use single-channel images (grayscale) as input, instead of using three-channel images (RGB) as in the original proposition, aiming to increase its robustness while reducing the complexity of the input images. The technique was also tested with the application of two different preprocessing filters to enhance the objects’ contours on the single-channel images, one being the ”pencil effect”, and the other based on local binary patterns (LBP). With this study, it was possible to evaluate the impact on the CNN detection performance due to the application of both of the filters. The proposed technique used with one channel images and the filters on the images still could not surpass the results of the technique with the three-channel image (RGB), although it indicated paths for improvement. The pencil filter also proved to be more robust than the LBP filter, as expected.

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