Controlled inertia tensor of a transformable spacecraft

2021 ◽  
Author(s):  
R.P. Simonyants ◽  
N.A. Alekhin ◽  
V.A. Tarasov
Keyword(s):  
Attitude Control ◽  
Dynamic Properties ◽  
Operating Conditions ◽  
Inertia Tensor ◽  
Simplified Model ◽  
Diagonal Form ◽  
Transformation Mechanism ◽  
External Disturbances ◽  
Type Transformation ◽  
Gravitational Moment

A simplified model of a transformable spacecraft is considered, including a rod-type transformation mechanism with movable weights. The mechanism can be used to adapt the dynamic properties of the spacecraft to the environment or the operating conditions of on-board systems, for example, to counter the moments of external disturbances during attitude control and angular stabilization. By changing the position of the transformation mechanism, the spacecraft inertia tensor can be put in diagonal form, which makes it possible to exclude the force interconnections between the channels and to eliminate the constant component of the gravitational moment. For a simplified model of the transformation mechanism, we establish the analytical dependence of the components of the inertia tensor on the parameters determining the position of the transformation mechanism. It is shown that by adjusting the moving mass, which is 0.5% of the entire spacecraft mass, we obtain the spacecraft configuration that ensures the diagonality of the inertia tensor.

Managing Flow Induced Vibration in Subsea Jumpers

2021 ◽  
Author(s):  
Rakshith Naik ◽  
Yetzirah Urthaler ◽  
Scot McNeill ◽  
Rafik Boubenider
Keyword(s):  
Dynamic Properties ◽  
Fatigue Analysis ◽  
Management Program ◽  
Measured Data ◽  
Operating Conditions ◽  
Valuable Insight ◽  
Fe Model ◽  
Flow Induced Vibration ◽  
Vibration Measurements

Abstract Certain subsea jumper design features coupled with operating conditions can lead to Flow Induced Vibration (FIV) of subsea jumpers. Excessive FIV can result in accumulation of allowable fatigue damage prior to the end of jumper service life. For this reason, an extensive FIV management program was instated for a large development in the Gulf of Mexico (GOM) where FIV had been observed. The program consisted of in-situ measurement, modeling and analysis. Selected well and flowline jumpers were outfitted with subsea instrumentation for dedicated vibration testing. Finite Element (FE) models were developed for each jumper and refined to match the dynamic properties extracted from the measured data. Fatigue analysis was then carried out using the refined FE model and measured response data. If warranted by the analysis results, action was taken to mitigate the deleterious effects of FIV. Details on modeling and data analysis were published in [5]. Herein, we focus on the overall findings and lessons learned over the duration of the program. The following topics from the program are discussed in detail: 1. In-situ vibration measurement 2. Overall vibration trends with flow rate and lack of correlation of FIV to flow intensity (rho-v-squared); 3. Vibration and fatigue performance of flowline jumpers vs. well jumpers 4. Fatigue analysis conservatism Reliance on screening calculations or predictive FE analysis could lead to overly conservative operational limits or a high degree of fatigue life uncertainty in conditions vulnerable to FIV. It is proposed that in-situ vibration measurements followed by analysis of the measured data in alignment with operating conditions is the best practice to obtain a realistic understanding of subsea jumper integrity to ensure safe and reliable operation of the subsea system. The findings from the FIV management program provide valuable insight for the subsea industry, particularly in the areas of integrity management of in-service subsea jumpers; in-situ instrumentation and vibration measurements and limitations associated with predictive analysis of jumper FIV. If learnings, such as those discussed here, are fed back into design, analysis and monitoring guidelines for subsea equipment, the understanding and management of FIV could be dramatically enhanced compared to the current industry practice.

Damping Behavior of Blades From Small Radial Turbines

2015 ◽  
Author(s):  
David Hemberger ◽  
Dietmar Filsinger ◽  
Hans-Jörg Bauer
Keyword(s):  
Numerical Analysis ◽  
Dynamic Properties ◽  
Forced Response ◽  
Operating Conditions ◽  
Fe Model ◽  
Structural Damping ◽  
Aerodynamic Damping ◽  
Damping Behavior ◽  
Aerodynamic Properties ◽  
Radial Turbines

Next to excitation forces and the dynamic properties of mistuned structures the damping behavior is a key feature to evaluate the dynamic turbine blade response and thus the HCF life of a bladed disk (blisk). Just as the determination of the mistuning properties and the assessment of the vibration excitation, the evaluation of damping is also subject to uncertainty especially considering the wide operating range of a small radial turbine of a turbocharger. Since the total damping is composed of material damping, structural damping and aerodynamic damping, which are affected by parameters, like the eigenform of the vibration, the magnitude of the vibration amplitude and aerodynamic properties, the total damping can be strongly dependent on the operating conditions. The study at hand provides results from investigations that allow estimating the contribution of aerodynamic damping on the total damping. Experimental and numerical analysis of radial turbines from turbochargers for vehicular engines with variable turbine inlet vanes were performed. Measurements under different environmental conditions such as at rest and during operation, as well as unsteady CFD calculations and, coupled flow and structural calculations were carried out. A change in total damping could be found depending on the density of the surrounding gas by vibration measurements in operation on the hot gas test bench. But it was also shown that the total damping is decisively influenced by the mistuning of the structure. On one side the structural damping is varied by the variation in mistuned blade vibration amplitudes and otherwise the aerodynamic damping is influenced by the different inter blade phase angles (IBPA ) due to the mistuning, which is a symptom of geometric differences and material inhomogeneity in the wheels. Finally, the estimated total damping values were utilized in forced response calculations using a mistuned FE-model of a real turbine and excitation forces from unsteady CFD calculation. The magnitudes of the measured vibration amplitudes were compared with results from numerical analysis to validate the numerical model with focus on the investigation about the total damping. The deviation between the results was ±10% for different eigenforms and excitation orders.

Angular Rate Sensor Based on a Solid-State Wave Gyroscope with a Metal Resonator for Attitude Control, Stabilization and Navigation Systems

2021 ◽  
Vol 22 (7) ◽  
pp. 374-382
Author(s):  
V. Ya. Raspopov ◽  
V. V. Likhosherst
Keyword(s):  
Attitude Control ◽  
Angular Rate ◽  
Operating Conditions ◽  
Simultaneous Action ◽  
Navigation Systems ◽  
Angular Rate Sensor ◽  
Manufacturing Defects ◽  
Vibration Localization ◽  
Resonance Frequencies ◽  
Rate Sensor

The article describes the methods and test results of a solid-wave gyroscope (SVG) — an angular rate sensor (ARS), developed at the Department of Control Devices, Tula State University and manufactured by the serial plant of JSC "Michurinsky Plant" Progress "according to the technology it worked out. The metal resonator SVG-ARS is made of an elinvar alloy and has a cylindrical structure of different thickness, the lower part of which, with a smaller wall thickness, acts as a suspension for the upper cylinder, the resonator itself, which has a conical shape, providing better vibration localization at its end edge. Technological manufacturing defects, different frequencies and variability, are eliminated by balancing " by mass" based on the removal of excess metal at certain points on the end edge of the resonator. The electronic module provides the second mode of primary and secondary oscillations of the resonator edge arising during rotation and creates a signal to compensate for the Coriolis and quadrature components of the output signal at the nodes. The maximum amplitudes of the excitation and compensation signals do not exceed 10 V. Therefore, at large values of mechanical influences, the compensation circuit may not work out the increased signal and the SVG-ARS loses its operability. The total processing time of the compensation signal does not exceed 1 μs. The maximum power consumption of the electronic module is not more than 4 W. When testing for mechanical and temperature effects, the norms were used that are typical for similar devices (angular rate sensors) used on board aircraft. The tests were carried out on the bench equipment of a specialized enterprise. The stability of the zero signal and the scale factor was determined under the simultaneous action of the measured speed and temperature on the SVG-ARS. The values of the random walk and the instability of the zero signal were obtained from the Allan deviation plots. Their values provide a basis for the conclusion about the possibility of using the developed SVG for several hours on board dynamic aircraft in orientation, stabilization and navigation systems. It was found that SVG-ARS possesses impact strength and restores its measuring ability after impact. Tests for vibration resistance revealed resonance frequencies and frequency rangesin which the tested VTG-DUS sample can be used without significant modification. The results of vibration tests can be used to refine the design and control electronics for the operating conditions of a particular aircraft.

PLUG AND PLAY INNOSAT ACS SIMULATOR

2015 ◽  
Vol 76 (8) ◽  
Author(s):  
S. M. Sharun ◽  
M. Y. Mashor ◽  
Fadzilah Hashim
Keyword(s):  
Attitude Control ◽  
Operating Conditions ◽  
Matlab Simulation ◽  
Dynamics Model ◽  
Attitude Control System ◽  
Close Match ◽  
Novel Approach ◽  
Simulator Design ◽  
Hardware In Loop ◽  
Hardware In Loop Simulation

This research proposes a novel approach of satellite simulator design where the simulator will be in the form of both software and hardware. A software simulator will represent the satellite dynamics model, incorporating all the operating conditions of the satellite in orbit. The control algorithm for Attitude Control System (ACS) will be implemented on Rabbit Micro Controller (RCM4100) and the dynamics model of Innovative Satellite (InnoSAT) plant in PC have been tested using real-time hardware-in-loop-simulation (HILS) technique. The results that have been obtained show that the InnoSAT ACS simulator can produce as good result as MATLAB simulation for the InnoSAT plants. The MSE values that have been calculated also show that there are a close match between HILS and MATLAB simulation where the MSEs different value are small. From both results, it is enough to verify that the developed protocol working satisfyingly and seems to be possible to be implemented on the actual flight.

ROBUST HOVERING CONTROLLER FOR UNCERTAIN MULTIROTOR MICRO AERIAL VEHICLES (MAVS) IN GPS-DENIED ENVIRONMENTS: IMAGE-BASED

2016 ◽  
Vol 78 (6-13) ◽  
Author(s):  
Dafizal Derawi ◽  
Nurul Dayana Salim ◽  
Hairi Zamzuri ◽  
Mohd Azizi Abdul Rahman ◽  
Kenzo Nonami
Keyword(s):  
Flight Control ◽  
Attitude Control ◽  
Visual Servoing ◽  
Micro Aerial Vehicles ◽  
Fixed Target ◽  
External Disturbances ◽  
Control Loops ◽  
Aerial Vehicles ◽  
Multiple Uncertainties ◽  
Robust Flight Control

This paper proposes an image-based robust hovering controller for multirotor micro aerial vehicles (MAVs) in GPS-denied environments.  The proposed controller is robust against the effects of multiple uncertainties in angular dynamics of vehicle which contain external disturbances, nonlinear dynamics, coupling, and parametric uncertainties. Based on visual features extracted from the image, the proposed controller is capable of controlling the pose (position and orientation) of the multirotor relative to the fixed-target. The proposed controller scheme consists of two parts: a spherical image-based visual servoing (IBVS) and a robust flight controller for velocity and attitude control loops. A robust compensator based on a second order robust filter is utilized in the robust flight control design to improve the robustness of the multirotor when subject to multiple uncertainties. Compared to other methods, the proposed method is robust against multiple uncertainties and does not need to keep the features in the field of view. The simulation results prove the effectiveness and robustness of the proposed controller. 

Model-based model predictive control for a direct-driven permanent magnet synchronous generator with internal and external disturbances

2019 ◽  
Vol 42 (3) ◽  
pp. 586-597 ◽  
Author(s):  
Li Shengquan ◽  
Li Juan ◽  
Tang Yongwei ◽  
Shi Yanqiu ◽  
Cao Wei
Keyword(s):  
Permanent Magnet ◽  
Control Method ◽  
Synchronous Generator ◽  
Critical Issue ◽  
Operating Conditions ◽  
Maximum Power ◽  
External Disturbances ◽  
Permanent Magnet Synchronous Generator ◽  
Model Based ◽  
Wide Range

This paper deals with the critical issue in a direct-driven permanent magnet synchronous generator (PMSG)-based wind energy conversion system (WECS): the rejection of internal and external disturbances, including the uncertainties of external environment, rapid wind speed changes in the original parameters of the generator caused by mutative operating conditions. To track the maximum power, a maximum power point tracking strategy based on model predictive controller (MPC) is proposed with extended state observer (ESO) to attenuate the disturbances and uncertainties. In real application, system inertia and the system parameters vary in a wide range with variations of wind speeds and disturbances, which substantially degrade the maximum power tracking performance of wind turbine. The MPC design should incorporate the available model information into the ESO to improve the control efficiency. Based on this principle, a model-based MPC with ESO control structure is proposed in this paper. Simulation study is conducted to evaluate the performance of the proposed control strategy. It is shown that the effect of internal and external disturbances is compensated in a more effective way compared with the ESO-based MPC approach and traditional proportional integral differential (PID) control method.

scholarly journals Modelling Properties of an Alkaline Electrolyser

Energies ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 3073
Author(s):  
Krzysztof Górecki ◽  
Małgorzata Górecka ◽  
Paweł Górecki
Keyword(s):  
Potassium Hydroxide ◽  
Dynamic Properties ◽  
Operating Conditions ◽  
High Productivity ◽  
Electrolysis Process ◽  
Average Value ◽  
Current Voltage ◽  
Wide Range ◽  
Current Voltage Characteristics ◽  
Parameter Values

This paper proposes a model of an electrolyser in the form of a subcircuit dedicated for SPICE. It takes into account both the electric static and dynamic properties of the considered device and is devoted to the optimisation of the parameters of the signal feeding this electrolyser, making it possible to obtain a high productivity and efficiency of the electrolysis process. Parameter values the describing current-voltage characteristics of the electrolyser take into account the influence of the concentration of the potassium hydroxide (KOH) solution. A detailed description of the structure and all the components of this model is included in the paper. The correctness of the elaborated model is verified experimentally in a wide range of changes in the value of the feeding current and concentration of the KOH solution. Some computations illustrating the influence of the amplitude, average value, duty factor, and frequency of feeding current on the productivity and efficiency of the electrolysis process are performed. On the basis of the obtained results of the investigations, some recommendations for the operating conditions of electrolysers are formulated.

Energy Consumption Discussions of Porcelain Produce with Operating Conditions in a Simplified Model

2014 ◽  
Vol 936 ◽  
pp. 1775-1779
Author(s):  
Jun Liang Yu
Keyword(s):  
Energy Consumption ◽  
High Energy ◽  
Operating Conditions ◽  
Simplified Model ◽  
Net Energy ◽  
Mass Ratio ◽  
Solid Mass ◽  
Fuel Distribution ◽  
Total Energy Balance ◽  
Excess Number

Porcelain produce is a very high energy consumption process. According to total energy balance analysis, a variety of operating conditions are analyzed for effect of net energy consumption. One real porcelain plate produce process is introduced as the reference case. Operating conditions are defined in three parameters, which are air excess number, fuel distribution and solid mass ratio. A simplified model based on finite difference method (FDM) is solved to calculate axial gas and solid temperature profiles and net energy consumption. The net energy consumption in porcelain produce is calculated and discussed in quantity with three operating conditions above separately. Finally, it is concluded that net energy consumption is higher with bigger air excess number and solid mass ratio, while fuel distribution will have no influence on net energy consumption.

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