Algorithm for Spacecraft Angular and Translational Motion Control with use of Orientation Thrusters

2019 ◽  
pp. 30-40
Author(s):  
A.V. Sumarokov ◽  
P.A. Tyrnov
Keyword(s):  
Mathematical Modelling ◽  
Phase Plane ◽  
Translational Motion ◽  
Control Parameters ◽  
Control Vector ◽  
Method Of Least Squares ◽  
Solution Vector ◽  
Angular Velocities ◽  
Spacecraft Stabilization ◽  
Elastic Characteristics

The paper discusses the algorithm of spacecraft orientation and docking thrusters control for simultaneous spatial and angular motion. The solution of control velocity formation problem and the problem of required engines configuration determination along with the optimization of control vector execution accuracy are considered. The formation of control velocity is carried out using a phase plane with switching lines and a zone of inactivity. The calculation of thrusters working duration time is based on the method of least squares with non-negative resulting solution vector and additional boundary conditions. In the paper, the necessary control parameters were chosen to ensure the necessary accuracy of spacecraft stabilization. To demonstrate the developed algorithm, mathematical modelling of various considered spacecraft's orbital flight stages was executed, including damping of initial angular velocities, spatial motion, and stabilization under the influence of continuous perturbations. The simulation took into account the disturbing moments acting on the spacecraft, thrusters mounting errors and the characteristics of the angular velocity meter. The elastic characteristics of the structure were not taken into account. The results of mathematical modelling showed that the proposed algorithm coped well with the task, and was able to ensure the movement of the spacecraft center of masses in a given direction and simultaneous angular stabilization with required accuracy.

Nonlinear Dynamic Analysis of a Polydyne Cam With Translated Roller Follower Mechanism With Clearance

2018 ◽  
Author(s):  
Louay S. Yousuf ◽  
Anis Drira
Keyword(s):  
Fourier Transform ◽  
Lyapunov Exponent ◽  
Power Spectrum ◽  
Phase Plane ◽  
Nonlinear Dynamic Analysis ◽  
Power Spectrum Analysis ◽  
Largest Lyapunov Exponent ◽  
Experimental Setup ◽  
Angular Velocities ◽  
The Impact

In this paper, a polydyne cam with translated roller follower over a range of speeds are analyzed. There is a clearance between the follower and the guide. The dynamic simulation is investigated taking into account the impact and the friction. The simulation has been done by using Solidworks program. The effect of follower guides’ clearances on roller follower non-periodicity is considered based on Lyapunov exponent technique. Rosenstein method is used to calculate largest Lyapunov exponent for different angular velocities of the cam. The experimental setup has been implemented by using OPTOTRAK/3020 through a 3-D infrared markers to track follower motion. The power spectrum analysis of Fast Fourier Transform and phase plane contour are examined roller follower non-periodicity.

scholarly journals Identification and Stochastic Optimizing the UAV Motion Control in Turbulent Atmosphere

2021 ◽  
Vol vm02 (is02) ◽  
pp. 57-63
Author(s):  
Yevgeny Somov ◽  
Nikolay Rodnishchev ◽  
Tatyana Somova
Keyword(s):  
Stochastic Systems ◽  
Time Moment ◽  
Translational Motion ◽  
Stochastic Dynamic ◽  
Random Parameters ◽  
Nonlinear Stochastic Systems ◽  
Control Functions ◽  
Angular Velocities ◽  
Aerial Vehicle ◽  
Stochastic Dynamic Systems

In a class of diffusion Markov processes, we formulate a problem of identification of nonlinear stochastic dynamic systems with random parameters, multiplicative and additive noises, control functions, and the state vector at a final time moment. For such systems, the identifiability conditions are being studied, and necessary conditions are formulated in terms of the general theory of extreme problems. The developed engineering methods for identification and optimizing nonlinear stochastic systems are presented as well as their application for unmanned aerial vehicles under wind disturbances caused by atmospheric turbulence, namely, for optimizing the autopilot parameters during a rotary maneuver of an unmanned aerial vehicle in translational motion, taking into account the identification of its angular velocities.

Algorithms for estimating the motion of a spacecraft from its state data

2017 ◽  
Vol 13 (3) ◽  
pp. 3-13
Author(s):  
E. M. Abbasov
Keyword(s):  
Orbital Motion ◽  
Initial Conditions ◽  
Translational Motion ◽  
Extremal Point ◽  
Control Loop ◽  
Complex Dynamic ◽  
Method Of Least Squares ◽  
State Data ◽  
Object Based ◽  
Invariant Control

Control of processing processes on the state of the spacecraft (SC) is represented by schemes of the invariant control loop of a complex dynamic object. Based on the analysis of the algorithms for estimating the parameters of the translational motion of an aircraft (LA), based on the results of external trajectory measurements, an iterative Gauss-Newton procedure is formulated that implements the approach of directly finding the extremal point of the response surface described by a multidimensional function. Applied to the problem of estimating the initial conditions of motion of an aircraft. The features of the implementation of the algorithm for estimating the initial conditions of the orbital motion of the apparatus based on the method of least squares are investigated.

scholarly journals Analysis of a differential equation occurring in the theory of flame fronts

1994 ◽  
Vol 36 (1) ◽  
pp. 1-16 ◽  
Author(s):  
R. Grimshaw ◽  
J. Gan
Keyword(s):  
Differential Equation ◽  
Flame Front ◽  
Phase Plane ◽  
Front Propagation ◽  
Rapid Expansion ◽  
Control Parameters ◽  
Order Ordinary Differential Equation ◽  
Numerical Work ◽  
First Order ◽  
Crucial Component

AbstractRonney and Sivashinsky [2] and Buckmaster and Lee [1] have proposed a certain non-autonomous first order ordinary differential equation as a simple model for an expanding spherical flame front in a zero-gravity environment. Here we supplement their preliminary numerical calculations with some analysis and further numerical work. The results show that the solutions either correspond to quenching, or to steady flame front propagation, or to rapid expansion of the flame front, depending on two control parameters. A crucial component of our analysis is the construction of a barrier orbit which divides the phase plane into two parts. The location of this barrier orbit then determines the fate of orbits in the phase plane.

scholarly journals Optimal damping of deviations of angular speeds of an eightsymetric space aircraft

2021 ◽  
Vol 27 (4) ◽  
pp. 21-31
Author(s):  
А.A. Stenin ◽  
◽  
V.P. Pasko ◽  
I.G. Drozdovych ◽  
M.O. Soldatova ◽  
...  
Keyword(s):  
Fuel Consumption ◽  
Optimization Problem ◽  
Phase Plane ◽  
Initial Conditions ◽  
Artificial Gravity ◽  
Technical Equipment ◽  
Onboard Computer ◽  
Optimal Damping ◽  
Angular Velocities ◽  
Optimal Fuel Consumption

This paper considers the problem of optimal fuel consumption damping of sudden deviations of angular velocities of an axisymmetric spacecraft with a constant speed of rotation around the main axis of symmetry. This assumption has some practical significance and may be due to the creation of artificial gravity on the spacecraft. The idea of artificial gravity due to the rotation of an axisymmetric cylindrical spacecraft is based on the principle of equivalence of the force of gravity and the force of inertia. The urgency of the fuel consumption optimization problem is due to the presence of its limited stock onboard the spacecraft. The optimization problem is solved based on the maximum principle and the phase plane method. The authors of the article determine the structure of optimal fuel consumption processes with three levels of control, and the number of their switches depends on the initial conditions. Synthesized on the phase plane, the optimal switching curves divide the phase plane into eight curvilinear quadrants, which uniquely determine the values of the optimal control effects by the current values of the deviations of the angular velocities of the spacecraft. The problem of the possible presence of a delay in the control loop is proposed to be solved based on the Bess compensation method. To do this, the corresponding optimal curves of switching and disabling the controls are built as geometric locations of points remoted for the time of delay from the found curves of switching and the beginning of coordinates accordingly. It allows us to avoid the emergence of steady self-oscillations in a control contour and to provide a condition of keeping the spacecraft in a given final state after the completion of the stabilization process. Depending on the technical equipment of the spacecraft, two variants of the optimal damping algorithm are offered, namely: an autonomous device in the onboard control system of the spacecraft in the absence of a sufficiently powerful onboard computer, or the optimal damping algorithm, implemented entirely in the onboard computer of the spacecraft in case of its sufficient power.

Numerical Simulation and Neural Network Study Using an Upstream Cylinder for Flow Control of an Airfoil

2019 ◽  
Author(s):  
Meihua Zhang ◽  
Zhongquan Charlie Zheng ◽  
Yangliu Liu ◽  
Xiaoyu Jiang
Keyword(s):  
Neural Network ◽  
Numerical Simulation ◽  
Flow Control ◽  
Translational Motion ◽  
Back Propagation ◽  
Test Method ◽  
Immersed Boundary ◽  
Control Parameters ◽  
Reference Case ◽  
Drag Ratio

Abstract Flow behaviors of a downstream object can be affected significantly by an upstream object in close proximity. This concept is used for flow control in this study to maximize the lift/drag ratio on a NACA0012 airfoil. A cylinder with cross-flow translational motion is placed upstream of the airfoil. Numerical simulations are carried out with an immersed-boundary method to solve the incompressible, viscous flow at the Reynolds number of 2000. Control parameters that influence the dynamics of flow around the airfoil are systematically investigated, including the oscillating frequency and amplitude of the upstream cylinder, the distances between the cylinder and the airfoil, and the diameter of the cylinder. To obtain sample data properly and efficiently for carrying out the neural network study, the idea of the orthogonal test method is used to set the control parameters in the numerical simulation. The combination of the back-propagation neural network algorithm and the genetic algorithm is applied to find the optimal value of the lift/drag ratio and the corresponding control parameters. The results show that when the cylinder oscillating frequency increases, the ratio increases until negative coefficients occur; when the distance between the cylinder and the airfoil increases or the amplitude of oscillating cylinder increases, the ratio decreases first and then increases; and when the cylinder diameter increases, the ratio increases. Compared to the reference case, the optimized lift/drag ratio increases 178%.

Methods for Restricting Maximum Exposure Rate in Computerized Adaptative Testing

Methodology ◽  
2007 ◽  
Vol 3 (1) ◽  
pp. 14-23 ◽  
Author(s):  
Juan Ramon Barrada ◽  
Julio Olea ◽  
Vicente Ponsoda
Keyword(s):  
Measurement Accuracy ◽  
Computerized Adaptive Testing ◽  
Computation Time ◽  
Adaptive Testing ◽  
Exposure Rate ◽  
Control Parameters ◽  
The Impact ◽  
Two Alternatives ◽  
Selection Of ◽  
Maximum Exposure

Abstract. The Sympson-Hetter (1985) method provides a means of controlling maximum exposure rate of items in Computerized Adaptive Testing. Through a series of simulations, control parameters are set that mark the probability of administration of an item on being selected. This method presents two main problems: it requires a long computation time for calculating the parameters and the maximum exposure rate is slightly above the fixed limit. Van der Linden (2003) presented two alternatives which appear to solve both of the problems. The impact of these methods in the measurement accuracy has not been tested yet. We show how these methods over-restrict the exposure of some highly discriminating items and, thus, the accuracy is decreased. It also shown that, when the desired maximum exposure rate is near the minimum possible value, these methods offer an empirical maximum exposure rate clearly above the goal. A new method, based on the initial estimation of the probability of administration and the probability of selection of the items with the restricted method ( Revuelta & Ponsoda, 1998 ), is presented in this paper. It can be used with the Sympson-Hetter method and with the two van der Linden's methods. This option, when used with Sympson-Hetter, speeds the convergence of the control parameters without decreasing the accuracy.

Mathematical modelling of compatibility of normative and criteria evaluations

2012 ◽  
Author(s):  
Aleksandras Krylovas ◽  
Natalja Kosareva ◽  
Olga Navickiene
Keyword(s):  
Mathematical Modelling
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