RU2708412C1 - Control method of an unmanned gliding aircraft on trajectories with changes of directions of movement in the specified reference points - Google Patents

Abstract

FIELD: aviation.

SUBSTANCE: invention relates to a method of controlling an unmanned gliding aerial vehicle (UAV). To control the UAV, formulating and solving in each guidance cycle the boundary task of guiding UAV to each reference point of the trajectory in the accompanying coordinate system with the beginning on the current radius vector of the center of mass UAV at the height equal to the height of the next reference point of the trajectory, when approaching the guidance point to a distance at which it is possible to turn in a new direction of motion, formulating and solving a boundary value problem in a rectangular target coordinate system with a start at the guidance point, horizontally located axes of which in each homing cycle are unfolded according to a certain algorithm in the horizontal plane at small angles until completion of UAV trajectory turn in the direction of movement to the next reference point.

EFFECT: reduced losses of UAV speed at change of direction of movement.

1 cl, 1 dwg

Description

The invention relates to the field of guidance of unmanned planning aerial vehicles (UAVs) and can be used in the creation and operation of such aircraft.

Closest to this invention is the "Method for controlling an unmanned glider aircraft" (RU 2654238, 2018), based on the following main points:

1. The UAV moves in high atmospheric layers, has the ability to autonomously control the magnitude and direction of aerodynamic lift by means of a targeted change in the angle of aerodynamic roll ϕ and angle of attack α.

2. UAV control consists in sequential pointing at each of the set of reference points of the trajectory M _j (j = 1, ..., N) given by the geodetic coordinates B _j , L _j , H _j and their flight directions given by azimuth angles A _j and tilt to local horizons θ _j .

3. UAV guidance is carried out using the terminal guidance method “according to the required acceleration”, which includes solving the boundary guidance problem in order to determine the required acceleration, ensuring the UAV is transferred from the current position to the desired end position, specified at each regular reference point of the trajectory.

It is assumed that the current navigation parameters of the UAV are determined in the relative geocentric Greenwich rectangular coordinate system Oξηζ, in which the Oξ axis is northward along the Earth's rotation axis, the Oη axis in the equatorial plane crosses the Greenwich meridian, the Oζ axis complements the system to the right.

от центра масс БПЛА - точки S; ось S_cz_c - по нормали к плоскости П_с, образуемой двумя радиус - векторами

и

, исходящими из центра Земли. Ось S_cx_c дополняет целевую систему координат до правой.4. As the target coordinate system in which the boundary-value problem is formulated and solved, the accompanying coordinate system S _c x _c y _c z _c is selected with the start on the radius vector of the UAV center of mass at point S _c , the height of which is constant and equal to the height of the next point guidance. The axis S _c y _{c of the} system S _c x _c y _c z _{c is} directed along the radius vector

from the center of mass of the UAV - point S; axis S _c z _c - normal to the plane П _с , formed by two radius - vectors

and

emanating from the center of the earth. The S _c x _c axis complements the target coordinate system to the right.

The UAV motion equations in the boundary guidance problem are integrated under the following boundary conditions:

on the left end:

on the right end:

In formula (1), y = H (t) -H _j , and the projections of the velocity vector on the axis of the coordinate system S _c x _c y _c z _{c are} determined by the formula:

where the matrix of directional cosines connecting the relative geocentric Greenwich coordinate system with the current accompanying coordinate system is determined in each guidance cycle in the form:

Where

- центральный угол между векторами

и

.

is the central angle between the vectors

and

.

5. The solution of the boundary value problem in an analytical form in the analogue method was obtained under the assumption that the acceleration of gravity is constant and the influence of the Earth’s rotation on a continuously decreasing guidance section is insignificant, as well as when the required apparent acceleration is presented in the form of a simple integrable function — a first-order temporary polynomial:

The projections of the apparent acceleration obtained as a result of solving the boundary value problem on the axis of the accompanying coordinate system S _c x _c y _c z _c have the form:

6. The required value of the angle of the aerodynamic roll is calculated by the formula:

с помощью таблиц, представляющих зависимость коэффициента

от высоты Н, числа Маха М и угла атаки:The required value of the angle of attack α ^mp is determined after determining the required value of the coefficient of lifting aerodynamic force from the expression

using tables representing the dependence of the coefficient

from height H, Mach number M and angle of attack:

The disadvantage of the analogue method is that when changing the direction of the UAV movement to the next reference point M _{j + 1} in the new accompanying coordinate system at the stage of turning the trajectory in the boundary guidance problem, the value of the boundary conditions at the left end of the trajectory increases significantly - the values of the parameters V _z , y , V _y (see Fig. 1) and, as a result, the values of the required accelerations increase (see formulas (6), (7)), the angles of attack α ^mp and roll ϕ ^mp increase (see formulas (8) and ( 9)), and the consequence of an increase in the angle of attack is an increase in the aerodynamic force of the forehead new resistance and loss of UAV speed.

The task of the invention is to make changes in the UAV guidance algorithm for UAVs, which will significantly reduce UAV speed loss when changing directions of movement.

The technical result is achieved by the fact that the boundary-value problem of guiding the UAV to each successive reference point of the trajectory in each guidance cycle is formulated and solved in the accompanying coordinate system with the beginning on the current radius vector of the UAV's center of mass at a height equal to the height of the next reference point of the trajectory, and when approaching with the guidance point to the distance required to turn in a new direction of movement, the boundary guidance problem is formulated and solved in a rectangular target coordinate system with a beginning at the guidance point, horizon the perfectly spaced axes of which in each guidance cycle according to a certain algorithm are deployed in a horizontal plane at small angles up to the end of the UAV trajectory turning in the direction of movement to the next reference point.

The distance required to turn in a new direction of motion is determined in an angular measure by numerical experiments for all UAV trajectories equal to 1 degree of the central angle (from the center of the Earth) between the current radius vector and the radius vector of the guidance point.

Due to the smallness of changes in the orientation of the target coordinate system M _j xyz and the relative proximity of the UAV to the point of pointing the value of the boundary conditions and, accordingly, the required transverse accelerations and angles of attack will be small. Accordingly, the loss of UAV speed from atmospheric resistance will be small.

The invention is illustrated by the description below, figure 1 and is confirmed by an example of modeling the UAV trajectory when implementing the closest method and the proposed control method in tables 1, 2.

The essence of the proposed UAV control method is that, as in the closest analogue, the UAV is guided at each reference point with the determination of control parameters in the accompanying coordinate system S _c x _c y _c z _c , and from a certain distance to the reference point from which starts turning in the direction of the trajectory to the next reference point, the calculation of the control parameters is carried out in M _j xyz target coordinate system with the origin at the reference point, and a horizontally disposed axis in each cycle guidance deploying I at small angles toward the next supporting point (Fig. 1).

The UAV guidance algorithm with turning the trajectory to the next reference point includes:

, вычисляемыми в базовой системе координат Oξηζ:1. Setting the initial orientation of the target coordinate system M _j xyz orts

calculated in the base coordinate system Oξηζ:

- радиус-вектор БПЛА на момент начала разворота t_нn.Where

- the radius vector of the UAV at the beginning of the turn t _нn .

2. The task of the rotation of the axes of the axes M _j z and M _j x relative to the vertical axis M _j y by a small angle Δλ:

a) vector calculation

- единичный вектор, определяемый выражением:Where

is the unit vector defined by the expression:

,

- радиус-векторы опорных точек M_j и M_j+l,Where

,

are the radius vectors of the reference points M _j and M _{j + l} ,

Ф _{j, j + 1} is the angular distance between the reference points;

b) determination of the number of small rotations of the axes M _j z and M _j x into which the total angle of rotation of the axes is divided:

where _{ΔТ Цн} is the duration of the guidance cycle, k is the coefficient of multiplicity;

T is the predicted UAV flight time to the reference point, determined by the approximate formula:

после поворота на угол Δλ:c) determination of the position of the unit vector

after turning through the angle Δλ:

- малое изменение вектора

, соответствующее его повороту в горизонтальной плоскости на угол Δλ;Where

- small change in vector

corresponding to its rotation in the horizontal plane by the angle Δλ;

:d) determination of the new position of the unit

:

3. The formation of the boundary conditions of the guidance problem with a turn, the point M _{j + 1} in the coordinate system M _j xyz:

,on the left end -

,

,on the right end -

,

Where

and the elements of the matrix M _{x ← ξ are} determined by the components of its unit vectors:

Where

4. The solution of the boundary value problem with the determination of the required transverse accelerations at the time t + _{ΔТ Цн} / 2 in the form:

5. The determination of the required values of the control parameters — the angle of attack α ^mp and the angle of aerodynamic roll ϕ ^mp — is carried out in the same way as when solving the boundary value problem in the accompanying coordinate system, ie by formulas (8) and (9).

дальности полета и

скорости БПЛА в конечной точке траектории.The small values of α ^mp and ϕ ^mp in the sections of the turn of the trajectory when changing directions of motion provide small speed losses from the resistance of the atmosphere,

range and

UAV speed at the end point of the trajectory.

The results of comparative modeling of UAV flight using the developed UAV control method and control method described in the analogue [1] are presented in tables 1, 2.

Table 1

The results of modeling the UAV motion with the proposed control method

Legend: D — full spherical flight range, V — UAV flight speed, B — geodetic latitude, L — geodetic longitude, N — flight altitude, α — angle of attack, ϕ — aerodynamic roll angle, N _pop — transverse overload.

Claims (1)

A method for controlling an unmanned planning aircraft (UAV) on trajectories with changes in the direction of movement at given reference points, namely, that the boundary-value problem of guiding the UAV at each successive reference point of the trajectory in each guidance cycle is formulated and solved in the accompanying coordinate system with the beginning at the current radius vector of the center of mass of the UAV at a height equal to the height of the next reference point of the trajectory, characterized in that when approaching the guidance point to the distance required to turn in the direction of motion, the boundary guidance problem is formulated and solved in a rectangular target coordinate system with a beginning at the guidance point, the horizontal axes of which in each guidance cycle according to a certain algorithm are deployed in a horizontal plane at small angles until the UAV trajectory turns in the direction of travel to the next reference point.

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