scholarly journals CONTROL WITH REDUCING OF DISTURBING FACTORS

2019 ◽  
Vol 27 (4) ◽  
pp. 109-118
Author(s):  
Yuri Dmitrievich Sheptun ◽  
Sergey Viktorovich Spirkin
Keyword(s):  
Operating Time ◽  
Longitudinal Axis ◽  
Dynamic Features ◽  
Mass Asymmetry ◽  
Modeling Methods ◽  
Engine Thrust ◽  
Space Rocket ◽  
Thrust Vector ◽  
External Forces ◽  
Disturbed Motion

The structural and dynamic features of the space (moving outside the dense layers of the atmosphere) stages of rockets - carriers of spacecraft as control objects are analyzed. The reasons are investigated - disturbing factors that generate external forces and moments that determine the disturbed motion of space rocket stages. For space rocket stages, disturbing factors are: mass asymmetry of the stage relative to its longitudinal axis and angle of mismatch of the line of action of the thrust vector of the propulsion system of the stage with the longitudinal axis of the stage. It is shown that when using the stage control deviating in the hinge of the marching engine as the executive organs of the control system, the effect of auto-reduction of the mentioned disturbing factors arises. The consequence of the autocompensation of disturbing factors is the reduction of disturbing forces and moments that violate the programmed motion of the step in the pitch and yaw planes. Mass asymmetry and the angle of mismatch of the line of action of the thrust vector of its engine and the longitudinal axis of magnitude are constant. Therefore, a decrease in perturbing forces and moments is accompanied by a decrease in the amount of energy (fuel) spent on processing (zeroing) perturbations of the parameters of the perturbed motion of the stage. It is shown that if the thrust of a space-stage engine is 8000 kgf, the engine operating time (flight time of the stage) is 500 sec, the specific engine thrust is 330 sec, the mass asymmetry is 0.05 m, the angle of mismatch is 0.25 degrees, then fuel economy can reach 200 kgf. The studies were performed using mathematical modeling methods.

scholarly journals Thrust Vector Control of an Upper-Stage Rocket with Multiple Propellant Slosh Modes

2012 ◽  
Vol 2012 ◽  
pp. 1-18 ◽  
Author(s):  
Jaime Rubio Hervas ◽  
Mahmut Reyhanoglu
Keyword(s):  
Vector Control ◽  
Center Of Mass ◽  
Nonlinear Feedback ◽  
Thrust Vector Control ◽  
Engine Thrust ◽  
Mass Spring Model ◽  
Upper Stage ◽  
Thrust Vector ◽  
Mass Spring ◽  
Main Engine

The thrust vector control problem for an upper-stage rocket with propellant slosh dynamics is considered. The control inputs are defined by the gimbal deflection angle of a main engine and a pitching moment about the center of mass of the spacecraft. The rocket acceleration due to the main engine thrust is assumed to be large enough so that surface tension forces do not significantly affect the propellant motion during main engine burns. A multi-mass-spring model of the sloshing fuel is introduced to represent the prominent sloshing modes. A nonlinear feedback controller is designed to control the translational velocity vector and the attitude of the spacecraft, while suppressing the sloshing modes. The effectiveness of the controller is illustrated through a simulation example.

Energetics of constant height level bounding in quadruped robots

Robotica ◽  
2014 ◽  
Vol 34 (2) ◽  
pp. 403-422 ◽  
Author(s):  
Murali Krishna P. ◽  
Prasanth Kumar R.
Keyword(s):  
Body Mass ◽  
Mass Distribution ◽  
Specific Resistance ◽  
Ground Level ◽  
Longitudinal Axis ◽  
Mass Asymmetry ◽  
Quadruped Robots ◽  
First Case ◽  
Constant Height ◽  
Analytical Expressions

SUMMARYIn this paper, we investigate the energetics of constant height level bounding gaits in quadruped robots with asymmetric body-mass distribution along the longitudinal axis. Analytical expressions for mechanical specific resistance for two cases of bounding are derived: bounding with equal front and rear leg step lengths, and bounding with unequal front and rear leg step lengths. Specific resistance is found to be independent of mass distribution in the first case, and dependent in the second case. The quadruped robot has average nonzero acceleration/deceleration due to unsymmetric distribution of mass when front and rear leg step lengths are equal. Results show that lower body lengths, lower step lengths, and higher heights from the ground level give lower specific resistance. The effect of body-mass asymmetry is to accelerate in the first case, and to reduce specific resistance in the second case. This result provides some insight into why certain quadrupedal animals in nature evolved to have body-mass asymmetry.

Geometric Modeling Based on Class and Shape Function Transformation Technique for Hypersonic Vehicles

2016 ◽  
Vol 17 (3-4) ◽  
pp. 149-158
Author(s):  
Yanbin Liu ◽  
Bing Hua ◽  
Dibo Xiao
Keyword(s):  
Geometric Modeling ◽  
Shape Function ◽  
Hypersonic Vehicle ◽  
Hypersonic Vehicles ◽  
Dynamic Features ◽  
Aerodynamic Forces ◽  
Transformation Technique ◽  
Modeling Methods ◽  
Function Transformation ◽  
Simulation Results

AbstractThis paper presents the geometric modeling methods based on the class and shape function transformation (CST) technique for the hypersonic vehicle. First, the typical waverider configuration is considered to be the basic shape for the hypersonic vehicle, and then the CST method is applied to describe and build the improved geometric shape. On this basis, the aerodynamic forces and thrust are estimated according to the shock wave and Rayleigh flow theory. Furthermore, the model dynamic features using the CST method are analyzed in comparison to the basic shape. Finally, the simulation results show the effectiveness of this method for the hypersonic vehicle.

scholarly journals Development of a structural schematic of a bifunctional system for rocket engine thrust vector control

2018 ◽  
Vol 2018 (4) ◽  
pp. 57-67 ◽  
Author(s):  
G.A. Strelnykov ◽  
◽  
E.L. Tokareva ◽  
N.S. Pryadko ◽  
A.D. Yhnatev ◽  
...  
Keyword(s):  
Vector Control ◽  
Rocket Engine ◽  
Thrust Vector Control ◽  
Engine Thrust ◽  
Thrust Vector

scholarly journals Increasing the efficiency of an interceptor system for rocket engine thrust vector control

2020 ◽  
Vol 2020 (4) ◽  
pp. 13-28
Author(s):  
H.O. Strelnykov ◽  
◽  
O.L. Tokareva ◽  
O.D. Ihnatiev ◽  
N.S. Pryadko ◽  
...  
Keyword(s):  
Supersonic Flow ◽  
Vector Control ◽  
Rocket Engine ◽  
Control Force ◽  
Thrust Vector Control ◽  
Engine Thrust ◽  
Gas Dynamic ◽  
Working Medium ◽  
Combined Control ◽  
Thrust Vector

This work is concerned with studying the static and dynamic characteristics of the gas-dynamic (interceptor) subsystem of a combined system for thrust vector control and identifying ways to increase its efficiency. The combined control system includes a mechanical and a gas-dynamic subsystem. The gas-dynamic thrust vector control subsystem is the most important and reliable part of the combined control system. Consideration is given to disturbing the supersonic flow by installing a solid obstacle (interceptor) in the middle part of the rocket engine nozzle. An important advantage of this method to gas-dynamically control the rocket engine thrust vector is that the thrust vector control loss of the specific impulse is nearly absent because the control force is produced without any consumption of the working medium. Injection through the interceptor protects it against exposure to the nozzle supersonic flow and produces an additional lateral force. By now, the optimum height of the mass supply opening in the interceptor that maximizes the control force has not been determined, and the dynamic characteristics of this system have not been studied. The aim of this work is to find the optimum position of the opening for working medium supply through the interceptor that maximizes the added control force and to determine the effect of the transfer functions of the interceptor system components on the characteristics of the control force production transient. As a result of the study of the static characteristics of the supersonic flow disturbance in a nozzle with an interceptor through which a secondary working medium is injected, it is concluded that in terms of thrust vector control efficiency and interceptor protection the injection opening should be situated in the upper part of the interceptor. The transfer function of interceptor control of the liquid-propellant rocket engine thrust vector is obtained with account for the production of an additional control force by the injection of a liquid propellant component. It is found that the loss of stability of the operation of an injection interceptor unit depends on the transient of the working medium injection control valve.

Undulatory Propulsion

1953 ◽  
Vol s3-94 (28) ◽  
pp. 551-578
Author(s):  
J. GRAY
Keyword(s):  
Three Dimensional ◽  
Longitudinal Axis ◽  
Point Of View ◽  
The Body ◽  
Lateral Curvature ◽  
Tangential Forces ◽  
External Forces ◽  
Undulatory Swimming ◽  
Inclined Planes ◽  
The Waves

1. Typical undulatory progression over a rigid environment depends on three fundamental factors : (i) Internal bending couples change the lateral curvature of each region of the body to that previously characteristic of the region lying immediately anterior to itself. (ii) The phase of lateral bending varies along the length of the animal's body. (iii) The presence of external restraints prevents all regions of the body from moving along any path other than one tangential to their own circumference of curvature. 2. The magnitude of the forward tangential thrust imparted to the body depends on (a) the magnitude of the internally generated bending couples, and (b) the form of the waves. If friction operates on the surfaces of external restraint the thrust also depends on the coefficient of lateral friction and on the position of the restraints. 3. From a mechanical point of view, an undulating organism (irrespective of its size and internal structure) can be regarded either as a series of curved levers or as a series of inclined planes. 4. The general principles of undulatory swimming are the same as for a terrestrial glide, except for the fact that each element of the body must possess a component of motion normal to its surface if it is to contribute towards the propulsion of the animal; this type of motion can only occur when the waves move backwards relative to the ground. The animal cannot move forward as fast as the waves are propagated over the body. 5. The propulsive powers of three-dimensional waves are limited to the extent to which the organism is restrained by external forces from spinning about its own longitudinal axis. Otherwise the principles of progression are the same as for two-dimensional waves: the resultant of all the forces acting normally to the body is equal but opposite to that of all tangential forces.

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