scholarly journals Research on Instability Boundaries of Control Force for Trajectory Correction Projectiles

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Rupeng Li ◽  
Dongguang Li ◽  
Jieru Fan
Keyword(s):  
Coordinate System ◽  
Numerical Simulations ◽  
Stability Criterion ◽  
Feedback Loop ◽  
Control Force ◽  
Relevant Research ◽  
Force Magnitude ◽  
Roll Rate ◽  
Novel Method ◽  
Trajectory Correction

The balance of stability and maneuverability is the foundation of the trajectory correction projectile. For the terminal correction projectile without an attitude feedback loop, a larger control force is expected which may cause an instability. This paper proposes a novel method to derive instability boundaries for the control force magnitude. No additional coordinate system is needed in this method. By introducing the concept of angular compensation matrix, the exterior ballistic linearized equations considering control force are established. The necessary prerequisite for a stable flight under control is given by the Routh stability criterion. The instability boundaries for the control force magnitude are derived. The results of example flights are 13.5% more accurate compared with that in relevant research. Numerical simulations demonstrate that if the control force magnitude lies in the unstable scope derived in this paper, the projectile loses its stability. Furthermore, the effects of the projectile pitch, velocity, and roll rate on flight stability during correction are investigated using the proposed instability boundaries.

scholarly journals Tuning of a Linear-Quadratic Stabilization System for an Anti-Aircraft Missile

Aerospace ◽  
2021 ◽  
Vol 8 (2) ◽  
pp. 48
Author(s):  
Witold Bużantowicz
Keyword(s):  
Analytical Solutions ◽  
Feedback Loop ◽  
Linear Quadratic Regulator ◽  
Added Value ◽  
Tuning Parameter ◽  
Stabilization System ◽  
Linear Quadratic ◽  
Quadratic Stabilization ◽  
Novel Method ◽  
Selection Of

A description is given of an application of a linear-quadratic regulator (LQR) for stabilizing the characteristics of an anti-aircraft missile, and an analytical method of selecting the weighting elements of the gain matrix in feedback loop is proposed. A novel method of LQR tuning via a single parameter ς was proposed and tested. The article supplements and develops the topics addressed in the author’s previous work. Its added value includes the observation that the solutions obtained are symmetric pairs, and that the tuning parameter ς proposed for the designed linear-quadratic regulator enables the selection of suitable parameters for the airframe stabilizing loop for the majority of the analytical solutions of the considered Riccati equation.

scholarly journals Novel Remanence Determination for Power Transformers Based on Magnetizing Inductance Measurements

Energies ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4616
Author(s):  
Chen Wei ◽  
Xianqiang Li ◽  
Ming Yang ◽  
Zhiyuan Ma ◽  
Hui Hou
Keyword(s):  
Numerical Simulations ◽  
Laboratory Experiments ◽  
Power Transformer ◽  
Power Transformers ◽  
Inrush Current ◽  
The Core ◽  
Novel Method ◽  
Simulation Results ◽  
Electro Magnetic ◽  
The Relationship

The remanence (residual flux) in the core of power transformers needs to be determined in advance to eliminate the inrush current during the process of re-energization. In this paper, a novel method is proposed to determine the residual flux based on the relationship between residual flux and the measured magnetizing inductance. The paper shows physical, numerical, and analytical explanations on the phenomenon that the magnetizing inductance decreases with the increase of residual flux under low excitation. Numerical simulations are performed by EMTP (Electro-Magnetic Transient Program) on a 1 kVA power transformer under different amounts of residual flux. The inductance–remanence curves are nearly the same when testing current changes. Laboratory experiments conducted on the same transformer are in line with the numerical simulations. Furthermore, numerical simulation results on a 240 MVA are reported to demonstrate the effectiveness of the proposed method.

scholarly journals Investigation of a Multitasking System for Automatic Ship Berthing in Marine Practice Based on an Integrated Neural Controller

Mathematics ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 1167
Author(s):  
Van Suong Nguyen
Keyword(s):  
Neural Network ◽  
Neural Networks ◽  
Artificial Neural Networks ◽  
Coordinate System ◽  
Numerical Simulations ◽  
Neural Controller ◽  
The Neural Network ◽  
Artificial Neural ◽  
Ship Berthing

In this article, a multitasking system is investigated for automatic ship berthing in marine practices, based on artificial neural networks (ANNs). First, a neural network with separate structures in hidden layers is developed, based on a head-up coordinate system. This network is trained once with the berthing data of a ship in an original port to conduct berthing tasks in different ports. Then, on the basis of the developed network, an integrated mechanism including three negative signs is linked to achieve an integrated neural controller. This controller can bring the ship to a berth on each side of the ship in different ports. The whole system has the ability to berth for different tasks without retraining the neural network. Finally, to validate the effectiveness of the proposed system for automatic ship berthing, numerical simulations were performed for berthing tasks, such as different ports, and berthing each side of the ship. The results indicate that the proposed system shows a good performance in automatic ship berthing.

3D Curve Generation Using Spherical Polar Piecewise Interpolation in CAD and CAM

2020 ◽  
Vol 896 ◽  
pp. 224-228
Author(s):  
Mihai Dupac
Keyword(s):  
Path Planning ◽  
Coordinate System ◽  
Numerical Simulations ◽  
Trajectory Planning ◽  
Robot Arm ◽  
Polar Plane ◽  
Spherical Coordinate ◽  
Manufacturing Efficiency ◽  
Planning Approach ◽  
Design And Manufacturing

In this paper a newly 3D path planning approach and curve generation for design and manufacturing efficiency is considered. The 3D path is generated by a combination of piecewise interpolating curves - along a given number of via-points - created via a spherical coordinate system specified by the polar angles, radial distances and the associated azimuthal angles. Each piecewise interpolating curve is constructed using Hermite polar interpolation in the projective polar plane and the rotating azimuthal plane. To verify the proposed approach, numerical simulations for the generation of a helix design, a 4 and 6 leaf design and a trajectory planning of a picking robot arm are conducted.

scholarly journals Nonlinear Baroclinic Equilibration in the Presence of Ekman Friction

2012 ◽  
Vol 42 (2) ◽  
pp. 225-242 ◽  
Author(s):  
B. T. Willcocks ◽  
J. G. Esler
Keyword(s):  
Life Cycle ◽  
High Resolution ◽  
Numerical Simulations ◽  
Stability Criterion ◽  
Wave Amplitude ◽  
Ekman Number ◽  
Baroclinic Waves ◽  
Long Time ◽  
Baroclinic Adjustment ◽  
Degree Of Instability

Abstract Two theories for the nonlinear equilibration of baroclinic waves in a two-layer fluid in a β channel are tested by comparison with high-resolution numerical simulations. Predictions are tested for a range of parameters (β, κ), where the inverse criticality β measures the degree of instability and the quasigeostrophic Ekman number κ measures the strength of Ekman friction. The first theory, from Warn, Gauthier, and Pedlosky (WGP), is formally valid for marginally unstable waves at κ = 0. The second, from Romea, is formally valid for nonzero κ and for waves that are marginally stable with respect to a different criterion, which enters because of the dissipative destabilization of otherwise stable waves by Ekman friction. The predictions of the two theories are in conflict in the limit κ → 0. When κ is slightly greater than zero, it is found that the WGP accurately predicts the maximum wave amplitude attained during a baroclinic life cycle across a significant range of parameter space. By contrast, accurate predictions of the long-time asymptotic wave amplitude are obtained only from Romea’s theory, even for those cases where WGP describes the initial behavior during the life cycle accurately. The results first indicate the importance of understanding the nonlinear equilibration mechanism of dissipatively destabilized waves. Second, it follows that baroclinic adjustment theories formulated from inviscid and frictionless stability criterion make demonstrably incorrect predictions for the equilibrated state, even in the limit of vanishing Ekman friction.

Proposal and Experimental Verification of Design Guidelines for Centrifugal Compressor Impellers With Curvilinear Element Blades to Improve Compressor Performance

2014 ◽  
Author(s):  
Kiyotaka Hiradate ◽  
Kazuyuki Sugimura ◽  
Hiromi Kobayashi ◽  
Toshio Ito ◽  
Hideo Nishida
Keyword(s):  
Velocity Distribution ◽  
Coordinate System ◽  
Numerical Simulations ◽  
Centrifugal Compressor ◽  
Design Guidelines ◽  
Compressor Stage ◽  
Stall Margin ◽  
Cylindrical Coordinate ◽  
Forward Part ◽  
Stage Efficiency

This study numerically and experimentally examines the effects of applying curvilinear element blades to fully-shrouded centrifugal impellers on the performance of the centrifugal compressor stages. The design suction coefficient of the target impellers was 0.073. Our previous study confirmed that the application of curvilinear element blades could improve the stage efficiency of similar types of centrifugal compressors. However, a detailed explanation of the relation between the stall margin and the application of the curvilinear element blades remains to be given. The purpose of this study is to investigate the effects of using these blades on the impeller flow field and the stall margin in further detail. The curvilinear element blades we developed for centrifugal turbomachinery were defined by the coordinate transformations between a revolutionary flow-coordinate system and a cylindrical coordinate system. All the blade sections in the transferred cylindrical coordinate system were moved and stacked spanwise in accordance with the given “lean profile,” which meant the spanwise distribution profile of movement of the blade sections, to form a new leaned blade surface. The effects of the curvilinear element blades on the impeller flowfield were investigated by conducting numerical simulations using this method. We next considered the optimum design guidelines for impellers with curvilinear element blades. Then we designed a new impeller using these design guidelines and evaluated the performance improvement of a new compressor stage by conducting numerical simulations. As mentioned in several papers, we numerically confirmed that curvilinear element blades with a negative tangential lean profile improved the velocity distribution and stage efficiency because they help to suppress the secondary flows in the impeller. The negative tangential lean mentioned in this paper represents the lean profile in which the blade hub end leans forward in the direction of the impeller rotation compared to the blade shroud end. At the same time, we also found that the stall margin of these impellers deteriorated due to the increase in relative velocity deceleration near the suction surface of the shroud in the forward part of the impeller. Therefore, we propose new design guidelines for impellers with the curvilinear element blades by applying a negative tangential lean to line element blades in which the blade loading of the shroud side in the forward part of the impeller is reduced. We confirmed from the numerical simulation results that the performance of the new compressor stage improved compared to that in the corresponding conventional one. The new design guidelines for the curvilinear element blades were experimentally verified by comparing the performance of the new compressor stage with the corresponding conventional one. The measured efficiency of the new compressor stage was 2.4 % higher than that of the conventional stage with the stall margin kept comparable. A comparison of the measured velocity distributions at the impeller exit showed that the velocity distribution of the new impeller was much more uniform than that of the conventional one.

The Vibro-Mass Gyroscope

1983 ◽  
Vol 105 (1) ◽  
pp. 18-23 ◽  
Author(s):  
J. S. Burdess
Keyword(s):  
Control System ◽  
Sensitive Element ◽  
Feedback Loop ◽  
Control Force ◽  
Direct Measure

The paper examines the performance of a new two axis dynamically tuned gyroscope. Two types of feedback loop are described. In the first design the control force maintains the sensitive element in a near null position and provides a direct measure of the applied rate. Errors arising because of mistuning and damping are evaluated. The second design is constructed using regulator theory and the performance of the gyro is shown to be robust with respect to the parameters defining the gyro and its control system.

scholarly journals Dynamics of the Space Tug System with a Short Tether

2015 ◽  
Vol 2015 ◽  
pp. 1-16 ◽  
Author(s):  
Jiafu Liu ◽  
Naigang Cui ◽  
Fan Shen ◽  
Siyuan Rong
Keyword(s):  
Numerical Simulations ◽  
Initial Conditions ◽  
Geostationary Orbit ◽  
Euler Angles ◽  
Generalized Coordinates ◽  
Novel Method ◽  
Simulation Results

The dynamics of the space tug system with a short tether similar to the ROGER system during deorbiting is presented. The kinematical characteristic of this system is significantly different from the traditional tethered system as the tether is tensional and tensionless alternately during the deorbiting process. The dynamics obtained based on the methods for the traditional tethered system is not suitable for the space tug system. Therefore, a novel method for deriving dynamics for the deorbiting system similar to the ROGER system is proposed by adopting the orbital coordinates of the two spacecraft and the Euler angles of ROGER spacecraft as the generalized coordinates instead of in- and out-plane librations and the length of the tether and so forth. Then, the librations of the system are equivalently obtained using the orbital positions of the two spacecraft. At last, the geostationary orbit (GEO) and the orbit whose apogee is 300 km above GEO are chosen as the initial and target orbits, respectively, to perform the numerical simulations. The simulation results indicate that the dynamics can describe the characteristic of the tether-net system conveniently and accurately, and the deorbiting results are deeply affected by the initial conditions and parameters.

Numerical Simulations of Combustion and Decomposition Processes in Precalciner with Two Types of Locations of Jetting Coal Pipes

2012 ◽  
Vol 235 ◽  
pp. 428-433
Author(s):  
Shu Xia Mei ◽  
Jun Lin Xie ◽  
Feng He ◽  
Ming Fang Jin
Keyword(s):  
Calcium Carbonate ◽  
Coordinate System ◽  
Numerical Simulations ◽  
Transport Model ◽  
Solid Phase ◽  
Base Case ◽  
Discrete Phase Model ◽  
Actual Measurement ◽  
Air Inlet ◽  
Decomposition Processes

To reduce energy consumption, numerical simulations of combustion and decomposition processes in a precalciner were carried out with two types of locations of jetting coal pipes. In Euler coordinate system the gas phase is expressed with k-ε two-equation model, in Lagrange coordinate system the solid phase is expressed with discrete phase model (DPM), the chemical reaction is expressed with species transport model, and the radiation is expressed with P1 radiation model. For the base case the predicted burn-off rate of pulverized coal was 86%, and the decomposing rate of calcium carbonate was 92.9%, which are in accordance with actual measurement engineering data. The results show that when the jetting coal pipes are above the tertiary air inlet, the flow pattern of coal streams is more rational in the precalciner, being beneficial to the coal burn fully, resulting in a high temperature zone, around which the calcium carbonate decompose rapidly, than that when the jetting coal pipes are far away from the tertiary air inlet.

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