Papers by Dilmurat Azimov
Extending Explicit Guidance Methods to Higher Dimensions, Additional Conditions, and Higher Order Integration
Application of Cybenko’s Theorem and Algebraic Geometry in Solving Modified E-Guidance Equations
Vestnik Rossijskogo universiteta družby narodov, 2017
A complete analytical integration of the aircraft kinematic and dynamic equations of motion is pr... more A complete analytical integration of the aircraft kinematic and dynamic equations of motion is presented. Different applications of defined integrals to trajectory analysis are considered. The dynamic equations are obtained under the assumptions, that acceleration due to aerodynamic lift, the difference between the accelerations due to propulsive thrust and aerodynamic drag are not changed, the aircraft body rate about the velocity axis is zero and the sideslip angle is zero. The general integral of these equations consists of six independent first integrals of motion and describes a class of non-steady flight trajectories in a maneuver plane. It will be shown that the dynamic equations can be derived and completely integrated in a closed-form for more general assumptions. The problem of computing thrust for a given trajectory has been considered. The trajectory is defined by constraint equation. Constraints stabilization equations, which have asymptotically stable trivial solution, are constructed. Explicitness can make the integrals applicable to modeling the trajectories of spacecraft, re-entry vehicles and missiles, and to the design of on-board targeting and guidance. An illustrative example is presented.
Analytical approach to analysis of extremal trajectories and stability of programmed motion
Вестник Российского университета дружбы народов. Серия: Математика, информатика, физика, 2012
Hierarchical mixture of experts for autonomous unmanned aerial vehicles utilizing thrust models and acoustics
Robotics and Autonomous Systems
Semi-analytical and extremal solutions for design and synthesis of powered descent and landing trajectories
International Journal of Space Science and Engineering, 2021
New Approach to Multiple Data Association Processing for Initial Orbit Determination using Optical Observations
Real-Time Guidance, Navigation and Control Framework for Fixed-Wing Aircraft Maneuvers in a Vertical Plane
2018 International Conference on Unmanned Aircraft Systems (ICUAS), 2018
The goal of this study is to create a real-time guidance, navigation and control (GNC) framework ... more The goal of this study is to create a real-time guidance, navigation and control (GNC) framework for a fixed-wing aircraft (FWA) to perform various maneuvers in a vertical plane. This study offers a new approach for improving the FWA autonomy by enabling real-time sensor data fusion, targeting and re-targeting capabilities, new analytical/ numerical trajectory and attitude control solutions, and target-relative guidance. Existing FWA dynamical models are based on the traditional decoupling of their motion. This paper extends the utility of the concept of an instantaneous screw axis in guidance and control thereby promoting a new vision to general 6-degrees-of-freedom rigid body motion control. The existing flight vehicle guidance and control functions are mainly iterative and implicit, platform-specific, utilize pre-determined target states or way points, and executed typically utilizing the decoupled motion dynamical models. The research presented in this paper produces the GNC fra...
Mixture of Experts for Unmanned Aerial Vehicle Motor Thrust Models
ASME Letters in Dynamic Systems and Control
This study aims to analyze three unmanned aerial vehicles’ static and dynamic motor thrust models... more This study aims to analyze three unmanned aerial vehicles’ static and dynamic motor thrust models and to compare them with flight test telemetry motor angular velocity data as ground truth. This comparison determines which model is the most accurate based on the root mean square of the difference between the motor models and the telemetry data values. The Burgers and Staples models are dynamic thrust models with nonlinear drag, while the Gibiansky model is a static thrust model with linear drag. The mixture of experts (MoE) architecture assigns weights to each thrust model through a gating network such that higher weights map to the more accurate models. Flight tests include two maneuvers: triangle and shoelace loop. The triangle maneuver uses the cornering option to stop and turn at each waypoint. In contrast, the shoelace loop maneuver uses the curved option to fly smooth curves at waypoints instead of stopping and turning at each waypoint. Simulation results of the motor thrust m...
A new class of intermediate thrust arcs in the restricted three-body problem
Advances in Space Research
Extremal Control and Modified Explicit Guidance for Autonomous Unmanned Aerial Vehicles
Journal of Autonomous Vehicles and Systems
This study aims to develop and integrate guidance and control functions for applications such as ... more This study aims to develop and integrate guidance and control functions for applications such as rendezvous and docking, trajectory planning, entry descent and landing, executing maneuvers, and minimum fuel consumption. The utility of integrated nonlinear optimal control and explicit guidance functions replaces linear proportional-integral-derivative (PID) control laws. This approach leverages unmanned aerial vehicle (UAV) flight autonomy, thereby paving the way for creating an autonomous control technology with real-time target-relative guidance and re-targeting capabilities. A 360 deg roll maneuver combines extremal control and modified explicit guidance in which “explicit” means the acceleration commands are functions of time. The roll maneuver accurately reaches the desired position and velocity vectors through the proposed integration. Satisfying the first-order necessary optimality conditions demonstrates that the roll maneuver has extremal trajectories. To the best of the aut...
Motion With Constant Power and Constant Specific Impulse
Analytical Solutions for Extremal Space Trajectories, 2018
In this chapter, the thrust arcs with constant (in some cases, maximum) power and constant specif... more In this chapter, the thrust arcs with constant (in some cases, maximum) power and constant specific impulse will be studied. These arcs can be considered as the maximum or minimum thrust arcs as in both cases the power and the specific impulse are constants. In the same sense, both arcs can be related to a flight with low-thrust or high-thrust propulsion. The system of equations, which allows us to analyze various thrust arcs, including the IT arcs, have been derived. New solutions for the maximum (minimum) thrust arcs, including circular thrust arcs, in the Newtonian field have been obtained [137] .
Analytical Solutions for Extremal Space Trajectories, 2018
Aim: Anthropogenic landscape change, such as urbanization, can affect community structure and eco... more Aim: Anthropogenic landscape change, such as urbanization, can affect community structure and ecological interactions. Furthermore, changes in ambient temperature and resource availability due to urbanization may affect migratory and non-migratory species differently. However, the response of migratory species to urbanization is poorly investigated, and knowledge for invertebrates in particular is lacking. Our aim was to investigate whether there was a shift in community structure and phenology of hoverflies in urban landscapes, depending on migratory status. Methods: Using a paired design, we compared urban and rural landscapes to investigate the impact of urbanization on the abundance, diversity and phenology of hoverflies. Furthermore, we tested whether migratory and non-migratory species responded differently to urbanization. We observed a difference in the response of migratory and non-migratory hoverfly communities. Although the abundance of hoverflies was higher in the rural ecosystem, driven by a high abundance of migratory species, there was no difference in species richness between the land use types. However, the community structure of non-migratory species was significantly different between urban and rural ecosystems. The phenology of hoverflies differed between the two ecosystems, with an earlier appearance in the year of migratory species in urban landscapes. To our knowledge, this is the first study to investigate the response of migratory insect communities to urbanization. We demonstrated that migratory and non-migratory hoverflies respond differently to urbanization. This highlights the importance of differentiating between trait and mobility groups to understand community assemblage patterns in anthropogenic landscapes. The differences in phenology supports the growing evidence that urbanization not only affects the phenology of vegetation, but also affects the higher trophic levels. Changes in the phenology and community composition of species as a result of anthropogenic landscape change may have important implications for the maintenance of key ecosystem functions, such as pollination.
Motion With Variable Power and Constant Specific Impulse
Analytical Solutions for Extremal Space Trajectories, 2018
The thrust arcs with constant specific impulse can be formed by a low thrust or high thrust propu... more The thrust arcs with constant specific impulse can be formed by a low thrust or high thrust propulsion system. New analytical solutions for these arcs regardless the functional of the problem have been derived [112] , [113] , [114] . In particular, the Lawden spirals are studied in detail and the conclusions are made regarding their existence, optimality and applicability to the problems of space flight mechanics. The necessary conditions of optimality of these solutions, including the presence of conjugate points, are considered. The classification of the thrust arcs depending on the functional of the problem and given time is presented. The discussions of most of the questions considered in this chapter can be found in Ref. [61] , [67] , [68] , [148] , [149] , [150] .
Optimal and Extremal Trajectories
The purpose of this chapter is a brief description of the main elements of the calculus of variat... more The purpose of this chapter is a brief description of the main elements of the calculus of variations applicable to space flight mechanics and development of analytical approach to solving the variational problem stated in a form alternative to the Lawden's statement. First, the variation problem and existing methods of its solution are described. The first and second differentials of extended functional in the case when the extremal of the problem does not include corner points (discontinuity points of control vector), and necessary and sufficient conditions are presented. Furthermore, the variation problem, the formulation of which differs from the well known formulation of Lawden in flight dynamics is provided. Methodology of analytical determination of extremal trajectories is described.
Journal of Intelligent & Robotic Systems, 2021
Due to graduating and obtaining a job after graduation, the first author's affiliation has change... more Due to graduating and obtaining a job after graduation, the first author's affiliation has changed from the previous manuscript. Table shows the previous and current affiliation of the first author.
Derivation and integration of the 3-rd order vector differential equation of aircraft motion, and... more Derivation and integration of the 3-rd order vector differential equation of aircraft motion, and its applications to various dynamical models are presented. It is assumed that (a) acceleration due to aerodynamic lift, and the difference between the propulsive thrust and aerodynamic drag accelerations are not changed; (b) the bank angle is zero; (c) the sideslip angle is zero. The general integral and the corresponding analytical solutions for a class of non-steady flight trajectories consist of six independent integrals for heading angle, magnitude of velocity vector, time, altitude, and two components of the position vector. Explicitness with respect to the problem parameters can make these expressions useful in the design of trajectories, and the targeting and guidance schemes. Similarity in the corresponding models makes the first integrals valid for aircraft, spacecraft, re-entry vehicles and missiles. An illustrative example has shown that the general integral provides a wide ...
Enhanced Apollo Targeting for Lunar Landing
Extremal Trajectories in a Linear Central Field
This chapter presents analytical investigation of an optimal motion with maximum power and consta... more This chapter presents analytical investigation of an optimal motion with maximum power and constant specific impulse in the linear central field. Certain class of problems of space dynamics admit some simplifications based on the conditions in which a maneuver is performed. The problems of determining the trajectories in a thin spherical layer can be referred to this class of problems. These problems admit an approximation of the Newtonian field by a liner central field in the neighborhood of a reference orbit. The studies of flight trajectories show that it may be efficient to use short burns, generated by a high-thrust propulsion system when a spacecraft is in a thin spherical layer. Moreover, the low-thrust propulsion systems generate, in contrast, long arcs, which in many cases, may not also go beyond a thin layer. Therefore, this chapter addresses both high-thrust and/or low-thrust trajectories.
Some Problems of Trajectory Synthesis in the Newtonian Field
This chapter is devoted to the application of the methodology of construction of analytical extre... more This chapter is devoted to the application of the methodology of construction of analytical extremal trajectories in solving the practical problem of space flight dynamics. Each section of this chapter contains an example of a maneuver, to accomplish of which it is necessary to use one or more thrust arcs. The problems considered in this chapter illustrate the application of the method of using analytical solutions and their constants to determine the number of junction points and the sequence of thrust arcs. It has been proved that the solution of the variational problem, in general, is reduced to the solution of a certain number of algebraic equations constructed at the junction points. The possibility of synthesis of analytical extremal trajectories that satisfy the necessary optimality conditions and other conditions of the problem is demonstrated in Ref. [26] , [138] , [148] , [158] , [137] , [149] , [162] . The practical use of the analytical solutions is described in Ref. [14...
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Papers by Dilmurat Azimov