RU2059252C1 - Method of detecting vertical speed of object and apparatus for performing the method - Google Patents

Abstract

FIELD: in instrument making, namely for detection of vertical speed values of small-size movable objects, such as small-size and low-power flying vehicles of airplane type. SUBSTANCE: apparatus includes the pressure pickup 1, the differentiator 6, linear acceleration pickups 2-4, oriented along basic axis of the movable object and rigidly secured to a zone of its mass center, pickups 5 of rolling and pitching angles of the movable object, the multiplexer 7, the analog-to-digital converter 8, the adder 9, the multiplier 10, the integrator 12, the operative memory 11, the functional generator 13 and the digital-to-analog converter 14. Inputs of the multiplexer 7 are connected with outputs of the linear acceleration pickups 2-4, with an output of the pressure pickup 1, with an output of the differentiator 6. An input of the differentiator 6 is connected with an output of the pressure pickup 1, outputs of the pickups 5 of rolling and pitching angles. An output of the multiplexer 7 is connected with an input of the analog-to-digital converter 8, whose output is connected with outlet ports of the adder 9, the multiplier 10, the integrator 12, the operative memory 11, the functional generator 13, the digital-to-analog converter 14. Control inputs of above mentioned units are connected with outputs of the control unit 15. EFFECT: enhanced accuracy of detection of vertical speed value of movable objects. 3 cl, 2 dwg

Description

 The invention relates to instrumentation, and is specifically recommended for determining the vertical speed of small-sized moving objects, in particular small-sized and low-power aircraft of the aircraft circuit.

 A known device for measuring the vertical speed of an aircraft [1] In this device, the output signal is generated as the sum of the signal from the inertial vertical speed sensor and the correction, consisting of the integral of the difference between the output signal and the signal from the variometric vertical speed sensor. To this end, the output of the inertial vertical speed sensor is connected to the first input of the summing unit, and the variometric sensor output is connected to the first input of the subtracting unit, the output of the subtracting unit is connected via an integrator to the second input of the summing unit, and its output connected to the second input of the subtracting unit is the output channel .

 The known device allows you to partially compensate for the dynamic errors of the vertical speed meter due to the introduction of an acceleration signal along the vertical axis of the aircraft, which serves as an input signal for the inertial vertical speed sensor, however, due to the fact that the vertical acceleration of the aircraft in the earth's coordinate system does not coincide with its acceleration along the vertical axis in the coordinate system associated with the aircraft, when flying along a curved path, for example, at a turn, there will be errors in the measurement of vertical velocity, which can be very significant. Another source of vertical speed error is the dependence of the sensitivity of the variometric vertical speed sensor on the flight altitude. The foregoing allows us to state that for any parameters of the device circuit it is impossible to obtain a signal corresponding to the vertical velocity without amplitude and phase distortions.

The closest in technical essence is a method for determining the vertical speed of an object, implemented in a device for determining vertical speed, comprising a vertical acceleration sensor, a roll angle sensor, a variometric sensor and a computing unit [2]
The channel structure of the known device does not allow to obtain a signal corresponding to the vertical speed without dynamic distortions, since the signal of full vertical acceleration is replaced by its projection onto the vertical axis of the aircraft, and the signal corresponding to the barometric vertical speed is replaced by the signal from the variometric sensor, which depends on the flight altitude .

 The technical result of the invention improving the accuracy of measurement.

+

W_Б
(1) где W_Б K(p) ·dp/dt,

= a_xcsinν+a_усcosγcosν-a_zcsinγcosν-g, причем

где W значение вертикальной скорости объекта;

вертикальное ускорение объекта;
W_Б барометрическая вертикальная скорость;
X_c, Y_c, Z_c оси связанной системы координат подвижного объекта;
γ ν углы крена и тангажа соответственно;
a_xc, a_yc, a_zc линейные ускорения вдоль главных осей подвижного объекта;
g ускорение свободного падения;
K₁, K₂, K₃ коэффициенты передачи;
T постоянная интегрирования;
p оператор преобразования Лапласа.This is achieved by the fact that in addition to measuring the acceleration along the vertical axis and the angle of heel, accelerations are measured along the longitudinal and transverse axes of the object, the pitch angle, while the vertical speed is determined by the ratio of the form
W

+

W _B
(1) where W _B K (p) dp / dt,

= a _xc sinν + a _whisker cosγcosν-a _zc sinγcosν-g, and

where W is the vertical velocity of the object;

vertical acceleration of the object;
W _B barometric vertical speed;
X _c , Y _c , Z _c axis of the associated coordinate system of the moving object;
γ ν roll and pitch angles, respectively;
a _xc , a _yc , a _zc linear accelerations along the main axes of a moving object;
g acceleration of gravity;
K ₁ , K ₂ , K ₃ transmission ratios;
T integration constant;
p is the Laplace transform operator.

K (p) (dH / dt) (dp / dt), where dH / dt is the vertical speed of the moving object;
dp / dt rate of change of pressure of the medium.

 To implement the above method, a device is used that contains a pressure sensor, a differentiator, into which linear acceleration sensors are introduced oriented along the main axes of the moving object and rigidly fixed in the region of its center of mass, roll and pitch angle sensors of the moving object, multiplexer, analog-to-digital converter, adder , a multiplier, an integrator, random access memory (RAM), a functional converter and a digital-to-analog converter (DAC), with the inputs of the multiplexer the outputs of the linear acceleration sensors, the output of the pressure sensor, the output of the differentiator, the output of which is connected to the output of the pressure sensor, the outputs of the angle sensors of pitch and pitch are connected, the output of the multiplexer connected to the input of an analog-to-digital converter, the output of which is connected to the input-output ports of the adder, multiplier , integrator, RAM, functional converter, digital-to-analog converter, the control inputs of which are connected with the outputs of the control unit.

 Expression (1) corresponds to a procedure that can be illustrated by the block diagram shown in FIG. 1.

+

W_Б
(2)
Преобразовывая (2), получим
W

+

W_Б
(1) так как имеет место

= pW₄, (3) то, выражение (1) преобразуем к виду
W=

W₄+

W_Б
(4)
Принимая при рассмотрении работы устройства то, что погрешности определения вертикального ускорения, полученного с датчиков линейного ускорения и вертикальной скорости, полученной путем дифференцирования барометрического давления, малы (т.е. W₄ W_Б W), после преобразования выражения (4) получим
W

•

W₄
(5)
Если, коэффициенты при операторе Лапласа в числителе и знаменателе приравнять, т.е.A signal corresponding to the vertical acceleration of a moving object is fed to the input of a large-scale amplifier K1. A signal corresponding to the barometric vertical speed is applied to the input of the large-scale amplifier K2. The output signal of the device shown in FIG. 1, in the operator form is written as
W

+

W _B
(2)
Transforming (2), we obtain
W

+

W _B
(1) since it takes place

= pW ₄ , (3) then, we transform the expression (1) to the form
W =

W + ₄

W _B
(4)
Considering when considering the operation of the device that the errors in determining the vertical acceleration obtained from the linear acceleration sensors and the vertical velocity obtained by differentiating the barometric pressure are small (i.e., W ₄ W _B W), after transforming expression (4) we obtain
W

•

W ₄
(5)
If, the coefficients of the Laplace operator in the numerator and denominator are equalized, i.e.

(6) то выражение (5) преобразуется к виду
W

W₄
(7) В этом случае информация о вертикальной скорости без амплитудных и фазовых погрешностей и запаздывания передается на выход. При этом устраняется дрейф интегратора, обусловленный постоянным и медленно меняющимся смещением нуля в канале измерения вертикального ускорения, и устраняются высокочастотные помехи в канале измерения вертикальной скорости, характерные для барометрического метода, что иллюстрируется выражением (4). Выражение (6) является условием настройки фильтра.

(6) then expression (5) is transformed to
W

W ₄
(7) In this case, information about the vertical speed without amplitude and phase errors and delays is transmitted to the output. In this case, the integrator drift due to the constant and slowly changing zero offset in the vertical acceleration measurement channel is eliminated, and the high-frequency noise in the vertical velocity measurement channel, characteristic of the barometric method, is eliminated, which is illustrated by expression (4). Expression (6) is a condition for filter settings.

 In FIG. 2 shows a block diagram of a device for measuring the vertical speed of a moving object. The following designations are accepted: 1 pressure sensor; 2, 3, 4 linear acceleration sensors, oriented along the main axes of the moving object; 5 device for measuring the angle of inclination of a moving object; 6 differentiating device; 7 multiplexer; 8 analog-to-digital converter; 9 adder; 10 multiplier; 11 random access memory; 12 integrator; 13 functional converter; 14 digital-to-analog converter; 15 control unit.

 The outputs of the sensors 2, 3, 4 and the device for determining the angles of pitch and pitch 5 are connected to the inputs of the multiplexer 7, and the output of the pressure sensor 1 is also connected to the input of the differentiator 6, the output of which is connected to the input of the multiplexer 7. The output of the multiplexer 7 is connected to the analog input digital converter 8, the output of which in turn is connected to a data bus connecting the input-output ports of the adder 9, multiplier 10, random access memory 11, integrator 12, functional converter 13 and digital-to-analog the forming control unit 14. The outputs 15 through the control bus coupled to control inputs these blocks. The output signal of the device, proportional to the vertical speed, is removed from the output of the DAC.

 The device operates as follows.

 From the sensors, the signals corresponding to the mode of movement of the object will be received at the inputs of the multiplexer and the differentiator. The control unit, under the influence of an internal clock, performs a cyclic program and, at the same time, generates control signals that are fed to the control inputs of the functional units via the control bus, ensuring their operation in the following sequence.

 During the first clock cycles, the signal from the pressure sensor corresponding to the current pressure value P is received at the ADC input through the multiplexer. This signal is converted to a digital code and fed to the input of the functional converter, where it is converted to a code corresponding to the value of the coefficient K (P). During the following clock cycles, the signal from the differentiator proportional to the rate of change of pressure dp / dt will be transmitted to the ADC input through the multiplexer, converted into a digital code and fed to the first input of the multiplier, where it is stored. Then the digital code corresponding to the value of the coefficient K (p) from the output of the functional converter is fed to the second input of the multiplier, where it is multiplied with the first signal. At the output of the multiplier, a code appears corresponding to the product K (p) · dp / dt, which is fed to the RAM input, where it is stored.

Next, the signal corresponding to the current value a _{xc is} input to the ADC input through the multiplexer. This signal is converted into a digital code and fed to the first input of the multiplier, where it is stored. Then, the signal corresponding to the current value of ν is fed to the ADC input through the multiplexer and converted into a digital code. The code corresponding to the value of ν is fed to the input of the functional converter, the output of which is a digital code corresponding to the value of sin ν. From the output of the functional converter, this code is fed to the second input of the multiplier, where it is multiplied with the corresponding signal. The signal from the output of the multiplier corresponding to the value a _xc sin ν is fed to the first input of the adder, where it is stored.

Next, the multiplexer connects to the ADC input a signal corresponding to the value a _yc , where it is converted to a digital code and then fed to the first input of the multiplier, where it is stored. Then, a signal corresponding to the current value of γ is converted to a digital code and fed to the input of the functional converter through the multiplexer to the ADC input. At the output of the functional converter, a digital code appears corresponding to the value of cos γ which is then fed to the second input of the multiplier. After multiplying the signals at the first and second inputs of the multiplier, a digital code appears corresponding to the product a _yc cos γ which is again fed to the first input of the multiplier, where it is stored. Next, the multiplexer connects to the ADC input a signal corresponding to the value of ν. At the ADC output, it is converted to the corresponding digital code, which is fed to the input of the functional converter. At the output of the functional converter, a digital code is generated corresponding to the value of cosν and then fed to the second input of the multiplier. At the output of the multiplier, a signal appears corresponding to the product a _yc cosγ cosν which is then fed to the second input of the adder. The corresponding command is sent to the adder from the control unit and the above terms are added up, as a result of which the digital code corresponding to the value a _xc sinν + a _yc cosγ cosν arises at the output of the adder. This code again goes to the first input of the adder, where it is stored.

Then, through the multiplexer, the signal corresponding to the current value a _{zc is} input to the ADC input and converted into a digital code, which from the ADC output goes to the first input of the multiplier, where it is stored. Then, through the multiplexer, the signal corresponding to the γ value is converted to a digital code and fed to the input of the functional converter to the ADC input. Then, from the output of the functional converter, a digital code corresponding to the value sinγ is supplied to the second input of the multiplier. After multiplication, the digital code corresponding to the value from the output of the multiplier again goes to its input, where it is remembered.

Next, the signal corresponding to the current value of ν is converted to a digital code and fed to the input of the functional converter through the multiplexer to the ADC input. From the output of the functional converter, the digital code corresponding to the value of cosν is fed to the second input of the multiplier, and after performing the multiplication operation from the output of the multiplier, the digital code corresponding to the value of a _zc sinγ cosν is fed to the second input of the adder. By commands from the control unit, the adder is transferred to the subtraction mode and subtracts the second from the first term. As a result, a digital code appears on its output corresponding to the value a _xc sinν + a _yc cosγ cosν a _zc sinγ cosν Then this code is fed to the input of the functional converter, where the value corresponding to g is subtracted from this code and the difference is multiplied by the value K ₁ , Thus, the output generates a code corresponding to the value (a _xc sinν + a _yc cosγ cosν a _zc sinγ cosν g) K ₁ . Further, this code goes to the first input of the adder, where it is remembered. Then, by a command from the control unit, a digital code corresponding to the value of K (p) · dp / dt is supplied to the output of the RAM, and fed to the input of the functional converter, where it is multiplied by the value of K ₂ . The code corresponding to the value of [K (p) · dp / dt] · R ₂ then goes to the second input of the adder from the output of the functional converter. After the operation of summation, the code corresponding to the value (a _xc sinν + a _yc cosγ cosν a _zc sinγ cosν
g) K ₁ + + K ₂ K (p) dp / dt, which is again fed to the first input of the adder, where it is stored. Further, from the output of the integrator, the code corresponding to the value of the vertical speed is fed to the input of the functional converter. There, on command from the control unit, it is multiplied by the coefficient K ₃ and then, from the output of the functional converter, the code corresponding to the value of W · K ₃ is fed to the second input of the adder. The adder by commands from the control unit is transferred to the subtraction mode, subtracts the second signal from the first and a digital code corresponding to their difference appears at its output. The digital code from the output of the adder is fed to the input of the integrator. From the output of the integrator, a digital code corresponding to the measured value of the vertical speed is fed to the input of the DAC and then, after conversion into an analog signal, to the output of the device. Then the cycle described above is repeated.

 The advantage of the proposed method for measuring vertical velocity in comparison with the known solutions is the lack of dynamic errors in the output signal. This eliminates the integrator drift due to a constant and slowly changing zero offset in the channel for measuring vertical acceleration, and eliminates high-frequency noise in the channel for measuring vertical velocity characteristic of the barometric method.

Claims (2)

1. The method of determining the vertical speed of the object by the rate of change of the static pressure of the medium in which the object is moving, the acceleration of the movement of the object along the vertical axis and the angle of heel, characterized in that it additionally measure the acceleration along the longitudinal and transverse axes of the object, the pitch angle of the object, while vertical speed is determined by the ratio of the form

where W _{B is the} barometric vertical velocity, W _B K (P) • dP / dt;
W ₄ vertical acceleration of the object,

,

with γ, v roll and pitch angles, respectively;
a _{X c} , a _{Y c} , a _{Z c} linear accelerations along the main axes of the moving object;
g acceleration of gravity;
K ₁ , K ₂ , K ₃ transmission ratios;
T integration constant;
P Laplace transform operator;
K (P) (dH / dt) (dP / dt), where dH / dt is the vertical speed of the moving object;
dP / dt rate of change of pressure of the medium.  2. A device for determining the vertical speed of an object, comprising a linear acceleration sensor along the vertical axis of the object, a roll angle sensor and a computing unit, characterized in that a pressure sensor, a differentiator, linear acceleration sensors along the longitudinal and transverse axes of the object, a tangent angle sensor are inserted and the computing unit consists of a multiplexer, analog-to-digital converter, adder, multiplier, integrator, random access memory, functional converter, digital-to-analog the converter and the control unit, while the outputs of three accelerometers that are rigidly fixed in the vicinity of the center of mass of the object, the output of the pressure sensor, the output of the differentiator, the output of the pressure sensor, the outputs of the angle sensors of pitch and pitch are connected to the inputs of the multiplexer, and the output of the multiplexer is connected to input of an analog-to-digital converter, the output of which is connected to the input-output ports of the adder, multiplier, integrator, random access memory, functional converter, digital analog converter, the control inputs of which are connected with the outputs of the control unit.

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