Determining the Trajectory of the Crane Block Using the Finite Element Method

The paper discusses determining crane block trajectories using the finite element method (FEM). The mathematical formulation for air resistance of hooks’ block is presented with kinematic analysis of the block. The three crane blocks are considered: without wind deflector, with a spherical deflector and a cylindrical fairing. The hook block was assumed as a physical pendulum. The FEM analysis is provided with the hook block movement consideration. Movement trajectories of hook blocks for different wind speeds is depicted and the results are. At the end of the paper, the conclusions are provided with the directions of future research

The impact of the magnetization direction on the static and dynamic parameters of an electromagnetic linear actuator

This paper presents a simulation analysis of the impact of magnetization direction on the static and dynamic parameters of an electromagnetic linear actuator. The simulation analysis computations were completed for three different magnetization configurations of permanent magnets (i.e. axial, radial, and a Halbach array). The finite element method (FEM) was applied which provided a good representation of the properties of actual physical objects. The computations enabled an investigation into and an assessment of the impact of the runner magnetization method on the static and dynamic properties of the drive. Keywords: modelling and simulation, electromagnetic actuator, finite element method, field analysis, Halbach arra

Analiza układu napędowego z wykorzystaniem metody PIV w biomimetycznym bezzałogowym pojeździe podwodnym

The article presents a laboratory stand for direct measurement of the thrust generated by the undulating propulsion system of a biomimetic underwater vehicle. The laboratory water tunnel enables research and comparison of the generated thrust with the results of the fin and fluid interaction analysis using the Particle Image Velocimetry method. The water tunnel is equipped with an industrial camera for recording changes in the position of markers highlighted with a line laser in the area of analysis. The comparison of the results obtained by the PIV method with the industrial force sensor allows for the analysis of the efficiency of the biomimetic propulsion system as a function of both design and control parameters.W artykule przedstawiono stanowisko laboratoryjne do bezpośredniego pomiaru naporu generowanego przez napęd falowy biomimetycznego pojazdu podwodnego. Stanowisko umożliwia przeprowadzenie badań i porównanie generowanego naporu z wynikami analizy interakcji płetwy i płynu z wykorzystaniem metody PIV. Stanowisko wyposażone jest w kamerę przemysłową do rejestrowania zmiany położenia markerów podświetlonych liniowym laserem w obszarze analizy. Porównanie wyników uzyskanych metodą PIV z przemysłowym czujnikiem siły pozwala na analizę sprawności biomimetycznego układu napędowego w funkcji zarówno parametrów konstrukcyjnych jak i sterujących

Side Fins Performance in Biomimetic Unmanned Underwater Vehicle

This paper presents the experimental research conducted for the Biomimetic Unmanned Underwater Vehicle (BUUV). The study’s major goal is to create a single, flexible side fin with adequate proportions and stiffness for an energy-efficient propulsion system. The experiments were carried out in a laboratory water tunnel equipped with a sensor for direct thrust measurement for various fin dimensions. Further, the particle image velocimetry (PIV) approach was used for a more in-depth examination of fluid–structure interaction (FSI) phenomena. The given experiments indicate the region of superior propulsion system performance and explain the main aspects that have influenced thrust generation using image processing and the PIV approach

Strouhal Number Measurement for Novel Biomimetic Folding Fins Using an Image Processing Method

The aim of the paper is to present the parameters of new biomimetic folding fins measured using image processing. Tests were carried out for different types of folding biomimetic fins and compared to the most popular fins on the market. A noninvasive image processing method was used to estimate divers’ velocities in the vertical and horizontal directions and the frequency and the amplitude of the fin trailing edge, and as a result, the Strouhal number was calculated. These tests are a continuation of studies conducted in a water tunnel, where fin efficiency was measured as the ratio of generated thrust to electrical energy consumption, taking into account the mechanical efficiency of the leg manipulator as well as the water velocity. The Strouhal number helped us to analyse the parameters of the fin–diver–water system taking into account the properties of the fins, in particular the newly designed biomimetic folding fins

Applying the Geodetic Adjustment Method for Positioning in Relation to the Swarm Leader of Underwater Vehicles Based on Course, Speed, and Distance Measurements

The research consisted of simulating the movement of a single vehicle in relation to the swarm leader on a square-shaped path, taking into account measurement errors characteristic of typical cheap navigation devices and the hydroacoustic system. The research showed that these methods allow for estimating position coordinates with an accuracy of about 0.5 m (RMS) in the case of a calibrated navigation system and about 3.6 m (RMS) in the case of a non-calibrated navigation system. It also showed that it can provide a higher accuracy of estimating position coordinates in terms of abeam angles of the swarm leader (relative bearing equal to approximately ±90°), as well as while ensuring minimizing systematic errors values and proper estimation of mean errors values concerning course and speed measurements

Applying the Geodetic Adjustment Method for Positioning in Relation to the Swarm Leader of Underwater Vehicles Based on Course, Speed, and Distance Measurements

The research consisted of simulating the movement of a single vehicle in relation to the swarm leader on a square-shaped path, taking into account measurement errors characteristic of typical cheap navigation devices and the hydroacoustic system. The research showed that these methods allow for estimating position coordinates with an accuracy of about 0.5 m (RMS) in the case of a calibrated navigation system and about 3.6 m (RMS) in the case of a non-calibrated navigation system. It also showed that it can provide a higher accuracy of estimating position coordinates in terms of abeam angles of the swarm leader (relative bearing equal to approximately ±90°), as well as while ensuring minimizing systematic errors values and proper estimation of mean errors values concerning course and speed measurements

Analysis of the impact of changes in the stator magnetic circuit on static properties of the electromagnetic linear motor model

In this paper, the static characteristics as a function of changes in geometric dimensions of the stator magnetic circuit of the linear stepper actuator with permanent magnets is presented. The stator is built from a series of cylindrical coils encapsulated with ferromagnetic case. The runner is made of permanent magnet rings connected with ferromagnetic spacers. The electromagnetic interac-tion between the stator and the runner for the sequential supply of coils was analyzed. The electro-magnetic force as a function of the geometry of the coils and the ferromagnetic housing for the con-stant graduation of the runner was determined. The maximum, minimum, and average values of the electromagnetic force as a function of the geometric independent variable were determined. The ratio of the mean force to the maximum, and mechanical work calculated as the integral of the force on the path of the runner was adopted as the evaluation criteria. A comparison between the maximum, average and relative values of forces as a function of the geometric dimensions of the stator was made. Keywords: modelling and simulation, linear actuator, finite element method, field calculations, cogging force, magnetic force

Dual Quaternions for the Kinematic Description of a Fish–Like Propulsion System

This study discusses the use of quaternions and dual quaternions in the description of artificial fish kinematics. The investigation offered here illustrates quaternion and dual quaternion algebra, as well as its implementation in the software chosen. When it comes to numerical stability, quaternions are better than matrices because a normalised quaternion always shows the correct rotation, while a matrix more easily loses its orthogonality due to rounding errors and oversizing. Although quaternions are more compact than rotation matrices, using quaternions does not always provide less numerical computation and the amount of memory needed. In this paper, an algebraic form of quaternion representation is provided which is less memory-demanding than the matrix representation. All the functions that were used to prepare this work are presented, and they can be employed to conduct more research on how well quaternions work in a specific assignment

The Compass Error Comparison of an Onboard Standard Gyrocompass, Fiber-Optic Gyrocompass (FOG) and Satellite Compass

The aim of the presented research was to analyze the accuracy indications of three types of compass systems for the purposes of meeting warship modernization requirements. The authors of this paper have made an attempt to compare the accuracy of an onboard standard gyrocompass, a fiber-optic gyrocompass (FOG) and a satellite compass in real shipping circumstances. The research was carried out in the Gulf of Gdansk area, during the preparation of hydrographic surveys on stable courses. Three heading recordings have been taken into consideration. The helmsman’s operation and vessel inertia were analyzed and removed according to a spectrum analysis. Transient characteristics and the spectrum analysis (based on the Fourier transform theory and headings descriptions in the frequency domain) are presented. Data, processed using a band-stop finite impulse response (FIR) filter to reduce low-frequency heading distortions, are presented for further analyses. The statistics of errors of the compasses investigated, as well as the spectrum of these errors, are also presented. Based on accuracy measurements, the possibility of using the most accurate heading data as the input signal to the automatic ship control system was considered