RU2509692C1 - Method of control over spacecraft solar battery with protection against short-term faults of data on solar battery angular battery - Google Patents

Abstract

FIELD: transport.SUBSTANCE: invention relates to spacecraft electric power supply with the help of solar batteries. Proposed method consists in definition of preset angle of solar battery, measurement of its current angle and computation of design angle by angular velocity and spinning time. Solar battery acceleration angle (?) and deceleration angle (?) are defined. Solar battery is spinned to threshold of drop-away (?? (?) when mismatch between said preset and design angles is terminated. Before start of the control, preset angle is memorised to take initial preset angle as valid actual current angle. Mismatch threshold (?) of said angles proceeding from angles ?and ?as well as minimum tolerable currents of solar battery. Angle transducer circle is divided into equal discrete sectors by magnitude a given the condition ?+ ?< ? < ?. Discrete sector bisectors are taken to be measured magnitudes. Period of valid current angle definition is set to the order and exceeding maximum duration of transducer data fault and smaller than minimum interval of faults train. Said interval is divided to four equal interval while analysis of measured and memorised magnitudes in said intervals are reset to generate validity signal. In the latter case, solar battery is spinned to mismatch between design and preset angles ?to set new preset angle magnitude.EFFECT: higher survivability and efficiency.4 dwg

Description

The proposed method for controlling the orientation of the solar battery (SB) of a spacecraft (SC) with protection against short-term failures of information on the angular position of the solar battery relates to spacecraft power systems and can be used to control the orientation of solar panels of satellites, space stations, and other types of spacecraft.

Most modern spacecraft can function in Earth orbit for several years. For the operation of the spacecraft onboard equipment during the entire period of operation, it is necessary to provide it with electricity, which, as a rule, is generated using solar panels, with elements installed on it that convert the radiation of the sun into electric current. The magnitude of the current generated by the SB depends on the orientation of the plane of the working surface of the SB relative to the Sun. For automatic SB orientation, spacecraft control systems are used, which include on-board computers, which, in turn, implement control algorithms for spacecraft onboard equipment, including SB orientation control. The spacecraft control system manages the SB rotation device, which consists of electronic units and an electromechanical drive with a SB panel and an angle sensor rigidly fixed to its output shaft. The electronic components of the SB rotation device receive, convert commands generated from the spacecraft control system into the form necessary to control the SB electromechanical drive, and also convert information from the angle sensor into the form necessary for transmission to the spacecraft control system.

Using the algorithms of the motion control system implemented in the spacecraft control system, based on the information received from the corresponding sensors (for example, astro sensors or solar sensors), they determine the direction to the Sun and form a given angle of rotation of the SB.

SB orientation control algorithms receive information about a given angular position of the SB, as well as information about the current angular position of the SB with the SB panel fixed to it.

As a rule, the SB panel is mounted on the output shaft of the SB electromechanical drive so that the angle sensor generates a zero value when the normal to the SB working surface coincides with one of the coordinate axes associated with the spacecraft, for example, the yaw axis, and the SB rotation axis is parallel another, for example pitch axis.

Upon reaching a mismatch angle between a given angle and the SB angular position equal to the response threshold, the SB control algorithms initiate the issuance of SB rotation commands to reduce the mismatch angle, which are transmitted from the on-board automatic control system to the SB rotation device. When the mismatch angle is equal to the release angle, the SB control algorithms initiate commands to stop the rotation of the SB. The measurement of the angular position of the SB, as a rule, is carried out accurate to the discrete sector of the angle sensor. The reaction time of SB orientation control algorithms, as a rule, is a multiple of the computer cycle of the onboard computer of the spacecraft control system and amounts to several tens of milliseconds, for example, 100 ms [1].

It is known that as a result of the accumulation of electrostatic charges on the outer surface of the spacecraft's onboard equipment, including the cable network, short electrostatic discharges can occur periodically during its operation, tens of nanoseconds up to several microseconds long. Electrostatic discharges lead to the emission of electromagnetic energy and, thus, is accompanied by the generation of electromagnetic interference, which affects the operation of the spacecraft onboard equipment. In particular, this can lead to short-term malfunctions of information received from the angle sensor of the SB rotation device.

The maximum frequency of exposure to an electrostatic discharge does not exceed 2 Hz [2] and corresponds to a period of more than 500 ms, which, in turn, exceeds the mentioned period of 100 ms of operation of the spacecraft control system.

The closest technical solution adopted for the prototype is a method for controlling the orientation of the SB, which consists in determining the specified angle of the SB as the position of the projection of a unit direction vector on the Sun onto the plane of rotation of the normal to its working surface relative to the coordinate axes associated with the spacecraft, and measure the current angle SB as the angular position of the normal to the SB working surface in the plane of its rotation accurate to the discrete sector of the angle sensor, the calculated angle is calculated as the product of the SB angular velocity by time Duration of its rotation, they determine the run-up and braking angles, set the release threshold, less than which the mismatch between the set and calculated SB angles ceases, as:

α _OTP ≈α _TORM ,

where α _OTP is the release threshold,

rotate the solar battery in the direction of decreasing the mismatch between the calculated and predetermined angles and stop its rotation when the release threshold is reached [3].

The disadvantage of this method is that in the event of a malfunction in the information received from the SB angle sensor, the calculated angle may be corrected for the received erroneous value and, accordingly, the SB will be incorrectly oriented relative to the direction to the Sun. The consequence of this is a decrease in the current generated by the SB, which ultimately leads to a decrease in the survivability of the spacecraft and to the failure to fulfill the tasks assigned to it.

The technical task of the proposed method is to expand the functionality, increase the survivability and effectiveness of the control system for the orientation of the SB during short-term failures of information about the angular position of the SB coming from the angle sensor.

The specified technical result is achieved by the fact that in the known method of controlling the orientation of the solar battery of the spacecraft, which consists in determining the predetermined angle of the solar battery as the position of the projection of a unit direction vector onto the Sun on the plane of rotation of the normal to its working surface relative to the coordinate axes associated with the spacecraft , measure the current angle of the solar battery as the angular position of the normal to the working surface of the solar battery in the plane of its rotation with an accuracy of of the discrete sector of the angle sensor, calculate the calculated angle as the product of the angular velocity of the solar battery by its rotation time, determine the take-off and braking angles, set the release threshold, less than which the mismatch between the set and calculated angles of the solar battery stops:

α _OTP ≈α _TORM ,

where α _OTP is the release threshold,

they rotate the solar battery in the direction of reducing the mismatch between the calculated and predetermined angles and stop its rotation when the drop threshold is reached, additionally set the angular speed of rotation of the solar battery, which is an order of magnitude or more the angular speed of rotation of the spacecraft around the Earth, before the start of control, remember the given angle and take the initial value of the calculated angle for the reliable value of the current angle, set the mismatch threshold of the given and stored angles, as:

, $$\left({\alpha }_{R\mathrm{BUT}3G}+{\alpha }_{T\mathrm{ABOUT}RM}\right)<{\alpha }_{PR}<\arccos \frac{I_{MIN}}{I_{MAX}}$$

,

where α _RAG is the angle of acceleration of the solar battery;

α _TORM - angle of braking of the solar battery;

α _PR is the mismatch threshold of a given and stored angles;

I _MIN - minimum allowable current generated by solar

battery

I _MAX - the maximum possible current generated by the solar battery,

break the circle of the angle sensor into equal discrete sectors with the value:

(α _RAG + α _TORM ) <σ <α _PR ,

where σ is the angular value of one discrete sector of the angle sensor, take the positions of the bisectors of these discrete sectors corresponding to the values measured by the angle sensor, set the period for determining the reliable value of the current angle by an order of magnitude and more than the maximum duration of the failure of the information received from the angle sensor, and less than the minimum interval of the following failures the specified information, determine the reliable value of the current angle, while each of these periods is divided into four equal time intervals, in At the end of the first, second and third intervals, respectively, the first, second and third measured values of the current angle are stored, and at the end of the fourth interval, the first stored value when it coincides with the second or third stored values, or the second stored value coincides with the third one, and form a confidence signal, reset the confidence signal if there are no such matches or two of the three stored values do not correspond to the angular positions of the bisector from discrete sectors of the angle sensor, if the specified angle differs from the stored predetermined angle at the end of the previous rotation by more than the mismatch threshold between the specified angles, then the calculated angle is assigned the value of the valid current angle, if the difference between the calculated and valid current angles exceeds the value of the discrete sector of the sensor angle and a validity signal is generated, while the solar battery is rotated if the mismatch between the calculated and predetermined angles is greater than the release threshold, and when the release threshold is reached, the new value of the given angle is stored.

Figure 1 shows the flight of a spacecraft with SB in an orbit, figure 2 shows the position of the projection of a given direction on the Sun onto a plane formed by a circle of rotation of the normal to the working surface of the SB, as well as the positions of this normal measured by an angle sensor accurate to a discrete sector, figure 3 presents the sequence diagram of the formation of a reliable value of the angle sensor, figure 4 is a sequence _{diagram of} the change of a given α _REF , reliable α _ACCESS and the estimated α _CALCULATION values of the angles of the SB.

The proposed method of controlling the orientation of the solar battery of the spacecraft with protection from short-term failures of information about the angular position of the SB is implemented as follows.

In the process of designing the SB orientation control system, a SB rotation device with an electromechanical drive is selected that has an angular rotation speed of the output shaft with an SB mounted on it an order of magnitude or more of the angular velocity of the spacecraft rotation around the Earth, that is:

$${\omega }_{\mathrm{FROM}B}>10\cdot {\omega }_{\mathrm{TO}\mathrm{BUT}},\left(\mathrm{one}\right)$$

where ω _SB - constant angular velocity of rotation of the SB;

ω _SC - the angular velocity of rotation of the SC around the Earth.

According to the passport data, as well as the results of experiments at ground-based stands, the SB acceleration angle is determined as the angular value of the deviation of the normal to the SB working surface relative to the coordinate axes associated with the SC from the moment the SB rotation begins to reach a constant angular velocity, as well as the SB braking angle as a value the angular deviation of the indicated normal from the moment of termination of the mismatch between the given and calculated angles until the end of rotation. In addition, determine the minimum allowable current necessary to ensure the operability of the onboard equipment of the spacecraft, which should form the SB, as well as the maximum possible current, which can form the SB.

As you know, the current generated by the SB depends on the magnitude of the angle of deviation of the normal to the working surface of the SB from the direction to the Sun and can be defined as:

$$I=I_{MAX}\cdot \cos {\alpha }_P\left(2\right)$$

where α _P is the mismatch angle between the direction to the Sun and the normal to the working surface of the SB;

I is the current generated by the SB;

I _MAX - the maximum possible current that can produce SB.

During the design process, the maximum permissible deviation of the normal to the SB working surface from the direction to the Sun during the spacecraft flight in a given orbit is determined, at which the SB produces the minimum permissible current indicated above, and the mismatch threshold of the given and stored angles is set in the range:

$$\left({\alpha }_{R\mathrm{BUT}3G}+{\alpha }_{T\mathrm{ABOUT}RM}\right)<{\alpha }_{PR}<\arccos \frac{I_{MIN}}{I_{MAX}},\left(3\right)$$

where α _Razg - SB acceleration angle;

α _TORM - angle of braking SB;

α _PR is the mismatch threshold of a given and stored angles;

I _MIN is the minimum allowable current generated by the SB to ensure the functioning of the spacecraft onboard equipment;

I _MAX is the maximum possible current that the SB can generate when the spacecraft flies in a given orbit.

The angle sensor located on the output shaft of the electromechanical drive of the SB rotation device is a 360 ° circle, divided into equal discrete sectors, that is:

$$\sigma =\frac{{360}^o}{n},\left(\mathrm{four}\right)$$

where σ is the angular value of the discrete sector of the angle sensor;

n is the number of discrete angular sectors.

 The value of the discrete sector of the angle sensor is set in the range:

$$\left({\alpha }_{R\mathrm{BUT}3G}+{\alpha }_{T\mathrm{ABOUT}RM}\right)<\sigma <{\alpha }_{PR}.\left(5\right)$$

As a rule, the mismatch threshold of a given and stored angles is selected in the range of 5 ° -15 °, and the acceleration and braking angles do not exceed 1 °.

The SB angle sensor is mounted on the output shaft of the electromechanical drive of the SB rotation device in such a way that the angular value generated by it corresponds to the position of the normal to the SB working surface relative to the coordinate axes associated with the spacecraft. During the rotation of the SB, the angle sensor generates an angular value corresponding to the position of the bisector of the discrete sector, within which this normal is located.

During the flight of the spacecraft, the specified angle is determined as the position of the projection of a unit direction vector on the Sun onto the plane of rotation of the normal to its working surface relative to the coordinate axes associated with the spacecraft.

The calculated angle is calculated as the product of the angular velocity of the SB by the time of its rotation.

At the development stage, a release threshold is set, less than which the mismatch between the given and calculated angular position of the normal to the SB working surface is terminated, as:

α _OTP ≈α _TORM .

The initial value of the calculated angle is taken as the reliable value of the current angle. The determination of the reliable value of the angle sensor during the operation of the SB orientation control system is carried out for four equal time intervals into which the period for determining the reliable value of the current angle is divided, that is:

$$T_D=\mathrm{four}\cdot T_{\mathrm{AND}},\left(6\right)$$

where T _D - the period of determining the reliable value of the current angle;

T _And - the time interval equal to a quarter of the period for determining the reliable value of the current angle.

As a rule, the period for determining the reliable value of the current angle is chosen as a multiple of the computer cycle of the onboard computer of the spacecraft control system. A reliable value of the angle is formed if two of the three measured values of the angle sensor in one period coincide, while the period for determining the reliable value of the current angle is set in the range:

$$10\cdot {\tau }_{MAX}<T_D<T_{MIN},\left(7\right)$$

where τ _MAX is the maximum duration of faulty information coming from the angle sensor;

T _MIN - the minimum interval for following the failures of the information received from the angle sensor.

To determine the reliable value of the current angle at the end of the first, second and third time intervals, the first, second and third measured values of the current angle are stored respectively, and at the end of the fourth interval, the first stored value is assigned to the reliable value of the current angle if it coincides with the second or third, or the second, if it coincides with the third stored value, while generating a signal of reliability. If there are no such coincidences or the measured value does not correspond to the angular position of the bisector of one of the discrete sectors of the angle sensor, the validity signal is reset, that is, for each period:

$$\begin{array}{l}e\mathrm{from}l\mathrm{and}{\alpha }_{\mathrm{AND}3i\left(\mathrm{one}\right)}={\alpha }_{\mathrm{AND}3i\left(2\right)},t\mathrm{about}{\alpha }_{D\mathrm{ABOUT}\mathrm{FROM}Ti}={\alpha }_{\mathrm{AND}3i\left(\mathrm{one}\right)},U_{Di}=\mathrm{one,}\\ e\mathrm{from}l\mathrm{and}{\alpha }_{\mathrm{AND}3i\left(2\right)}={\alpha }_{\mathrm{AND}3i\left(3\right)},t\mathrm{about}{\alpha }_{D\mathrm{ABOUT}\mathrm{FROM}T}={\alpha }_{\mathrm{AND}3\left(2\right)},U_{Di}=\mathrm{one,}\\ e\mathrm{from}l\mathrm{and}{\alpha }_{\mathrm{AND}3i\left(\mathrm{one}\right)}\ne {\alpha }_{\mathrm{AND}3i\left(2\right)},\mathrm{and}{\alpha }_{\mathrm{AND}3i\left(2\right)}\ne {\alpha }_{\mathrm{AND}3i\left(3\right)},\mathrm{and}{\alpha }_{\mathrm{AND}3i\left(\mathrm{one}\right)}\ne {\alpha }_{\mathrm{AND}3i\left(3\right)}\mathrm{,,}{U}_{Di}=0\left(8\right)\end{array}$$

where α _{IZi (1)} , α _{Ii (2)} , α _{Ii (3)} - the current measured and stored values by the angle sensor at the end of the first, second and third intervals of determining reliability on the i-th rotation cycle;

α _DOSi - reliable value of the angle sensor on the i-th rotation cycle;

U _Di is the confidence signal on the i-th rotation cycle;

i is the rotation cycle number, i≥0.

In the presence of short-term interference caused, for example, by electrostatic discharge, faulty information is generated, which arrives from the angle sensor through the SB electronic units to the spacecraft control system. The duration of the angle sensor failure corresponds to the duration of the interference.

For example, the system in question has an angular velocity of rotation of the SB of ω _SB = 0.6 degrees / s, the discrete sector of the SB angle sensor is σ = 6 °, the maximum duration of the failure of the SB angle sensor information caused by electrostatic discharge is τ _MAX = 1.5 μs, the minimum period of the following failures T _MIN = 1 s, which corresponds to a frequency of 1 Hz.

For the considered option, if the calculation cycle of the spacecraft control system is a multiple of the computer cycle of the spacecraft control system of 100 ms and corresponds to the measurement interval T _AND = 200 ms [1], conditions (6), (7) are satisfied, since:

10 · τ _MAX = 10 · 1.5 μs = 0.000015 s;

T _D = 4 · T _I = 4-200 ms = 0.8 s;

T _MIN = 1 s.

Before starting the control, the set angle is stored and the initial value is set to the calculated angle, that is:

$${\mathrm{<figure-callout\; id="3"\; label="\alpha "\; filenames="00000017.png"\; state="\{\{state\}\}">\alpha </figure-callout>}}_{3\mathrm{BUT}D\left(i-\mathrm{one}\right)}={\mathrm{<figure-callout\; id="3"\; label="\alpha "\; filenames="00000017.png"\; state="\{\{state\}\}">\alpha </figure-callout>}}_{3\mathrm{BUT}Di},{\alpha }_{R\mathrm{BUT}\mathrm{FROM}Hi}={\alpha }_0,\left(9\right)$$

where α _ZADi is the current value of the given angle at the time of the beginning of the 1st rotation;

α _{REF (i-1)} - the stored value of the specified angle at the time of the end of the (i-1) th rotation;

α ₀ - the initial value of the calculated angle;

α _{CALCULATION (i)} is the calculated angle on the i-th rotation cycle.

SB rotation is allowed if the current set angle differs from the set at the end of the previous rotation of the set angle by more than the mismatch threshold of the set and stored angles, that is, when:

$$|\; |\; |{\alpha }_{3\mathrm{BUT}Di}-{\mathrm{<figure-callout\; id="3"\; label="\alpha "\; filenames="00000017.png"\; state="\{\{state\}\}">\alpha </figure-callout>}}_{3\mathrm{BUT}D\left(i-\mathrm{one}\right)}|\; |\; |>{\alpha }_{PR},\left(10\right)$$

in this case, before the start of rotation, the value of the current valid angle is assigned to the calculated angle, if the difference between them exceeds the value of the discrete sector of the angle sensor and at the time of obtaining permission to rotate, a confidence signal is generated, that is:

$$\begin{array}{c}{\alpha }_{R\mathrm{BUT}\mathrm{FROM}Hi}={\alpha }_{D\mathrm{ABOUT}\mathrm{FROM}Ti}\\ e\mathrm{from}l\mathrm{and}|\; |\; |{\alpha }_{3\mathrm{BUT}Di}-{\mathrm{<figure-callout\; id="3"\; label="\alpha "\; filenames="00000017.png"\; state="\{\{state\}\}">\alpha </figure-callout>}}_{3\mathrm{BUT}D\left(i-\mathrm{one}\right)}|\; |\; |>{\alpha }_{PR}\mathrm{and}|\; |\; |{\alpha }_{R\mathrm{BUT}\mathrm{FROM}Hi}-{\alpha }_{D\mathrm{ABOUT}\mathrm{FROM}Ti}|\; |\; |>\sigma \mathrm{and}{U}_{Di}=\mathrm{one.}\left(\mathrm{eleven}\right)\end{array}$$

It should be noted that in the control process, the discrepancy between the calculated and actual angular position of the SB is gradually increased, since the real angular velocity of the SB is influenced by various factors: backlash in the mechanism of the electromechanical drive, change in the friction forces of moving parts under zero gravity, vacuum and under the influence of space and solar radiation, temperature effects, vibrations of the SB panel at the moments of the beginning and end of rotation, changes in inertia forces during spacecraft turns and others. Due to these factors, a gradual divergence of the actual angular position of the SB from the calculated one is observed.

The rotation of the SB starts if the current set angle and the stored set angle differ by more than the mismatch threshold between the indicated angles, and if the mismatch between the calculated and set angles is more than the release threshold, that is, when:

$$|\; |\; |{\alpha }_{R\mathrm{BUT}\mathrm{FROM}Hi}-{\alpha }_{D\mathrm{ABOUT}\mathrm{FROM}Ti}|\; |\; |>{\alpha }_{\mathrm{ABOUT}TP}.\left(12\right)$$

During rotation of the SB, the calculated angle is calculated as:

$${\alpha }_{R\mathrm{BUT}\mathrm{FROM}H}={\alpha }_{R\mathrm{BUT}\mathrm{FROM}Hi}+{\omega }_{\mathrm{FROM}B}\cdot t_{\mathrm{FROM}Bi},\left(13\right)$$

where α _RASCHi - the calculated value of the angular position of the SB at the time of the start of rotation;

t _SBi - time of rotation of the SB. Stop the rotation of the SB when the release threshold is reached:

$$|\; |\; |{\alpha }_{R\mathrm{BUT}\mathrm{FROM}Hi}-{\mathrm{<figure-callout\; id="3"\; label="\alpha "\; filenames="00000017.png"\; state="\{\{state\}\}">\alpha </figure-callout>}}_{3\mathrm{BUT}Di}|\; |\; |\le {\alpha }_{\mathrm{ABOUT}TP}\left(\mathrm{fourteen}\right)$$

while remembering the value of the current specified angle:

$${\mathrm{<figure-callout\; id="3"\; label="\alpha "\; filenames="00000017.png"\; state="\{\{state\}\}">\alpha </figure-callout>}}_{3\mathrm{BUT}D3i}={\alpha }_{3\mathrm{BUT}Di}.\left(\mathrm{fifteen}\right)$$

Figure 1 shows the flight of the spacecraft with SB in orbit, where:

1 - Earth;

2 - spacecraft orbit;

3 - the direction of radiation from the Sun;

4 - spacecraft body;

5 - SB panel;

6 - angle sensor SB;

N is the given direction of orientation of the SB as the projection of a unit direction vector on the Sun onto the plane of rotation of the normal to the working surface of the SB;

N _SB - normal to the working surface of the SB;

X, Y, Z - the axis of the coordinate system associated with the spacecraft, and the Z axis is directed perpendicular to the plane of the drawing up;

X _SB , Y _SB , Z _SB - the axis of the coordinate system associated with the SB, the Z axis of the _SB coincides with the Z axis and is also directed perpendicular to the plane of the drawing up;

Δα is the angular mismatch between the direction to the Sun and the normal to the working surface of the SB;

ω _O is the angular velocity of the spacecraft rotation around the Earth;

ω _SB - the angular velocity of rotation of the SB around the axis Z of the _SB .

In Fig. 1, a spacecraft rotates around the Earth 1 in orbit 2 with an angular velocity ω _O. In the direction of radiation of the Sun with respect to the spacecraft 3 4 Body carried Sa orientation panel 5. The angular position of the projections normal to the working surface Sa _Sa N relative to the unit vector direction to the sun N measured with angle sensor 6. On the housing 4 spacecraft rigidly connected axes X, Y, Z coordinate system. In turn, the axes X _SB , Y _SB , Z _SB form a coordinate system associated with the SB. The SB rotates around the Z axis of the _SB , directed perpendicular upward to the plane of the drawing, the directions of the Z axes of the _SB and Z coincide, and the plane formed by the X axes of the _SB and Y of the _{SB is} parallel to the plane formed by the X and Y axes. The normal direction to the working surface of the SB N _SB coincides with the direction of the X axis _SB .

The angle sensor SB 6 generates a zero value when the directions of the axes X _SB and X coincide. In accordance with the direction of the radiation of the Sun 3, the direction of the projection of a unit direction vector onto the Sun N on the plane formed by the axes X _SB and Y _{SB is} determined.

During the spacecraft’s flight in orbit 2 with an angular velocity ω _O, the SB 5 panel is deployed in such a way as to ensure a minimum mismatch angle Δα between the projection direction of the unit direction vector onto the Sun N on the normal rotation plane to the SB working surface formed by the X _SB and Y _SB axes and the indicated normal N _SB , as a result of which the formation of the maximum possible current is ensured.

When controlling the considered method, if the mismatch angle between the current specified angle, i.e. the position of the projection N, and the stored predetermined angle at the end of the previous rotation of the SB over the mismatch threshold of the given and stored angles, as well as the mismatch between the design angle, i.e. normal position N _SB , and a given angle, i.e. projection N, more than the release threshold, the SB panel 5 is deployed with the angular velocity ω _SB until the normal position of the N _{SB is} aligned with the projection position N.

Figure 2 presents the circle of rotation of the normal to the working surface of the SB, the position of which is measured by an angle sensor, where:

7 - circle of rotation of the normal to the working surface of the SB;

8 - the center of the circle of rotation of the normal to the working surface of the SB;

N is the given direction of orientation of the SB as the projection of a unit direction vector on the Sun onto the plane of rotation of the normal to the working surface of the SB;

N _SB - normal to the working surface of the SB;

α _σ0 , α _σ1 , α _σ2 , ..., α _σj , α _{(j + 1)} ... α _{σ (n-2)} , α _{σ (n-1)} - discrete sectors of the angle sensor;

N _Bj is the bisector of the discrete sector α _σj

α _PR is the mismatch threshold of a given and stored angles;

σ is the angular value of the discrete sector of the angle sensor.

α _RAS - the angle of mismatch between the current specified direction and the position of the normal to the working surface of the SB;

α _OTP - release threshold.

In Fig.2, the SB angle sensor is made in the form of a circle of rotation of the normal to the working surface of SB 7 with center 8. The 360 ° circle is divided into n equal discrete sectors α _σ0 , α _σ1 , α _σ2 , ..., α _σj , α _{(j + 1 )} ... α _{σ (n-2)} , α _{σ (n-1)} . The specified sensor is mounted on the spacecraft body in such a way that the zero position coincides with the X axis associated with the spacecraft coordinate system. Thus, measurement of the angular position of the normal to the working surface Sa _Sa N accurate to discrete sector value σ, wherein the angle sensor generates a value corresponding to the positions of the bisectors of each sector _{α σ0, ... α σ (n} - _1).

When controlling the considered method, the SB panel starts rotation when the angles are mismatched between the current N and the predetermined direction on the Sun N _recorded at the end of the previous rotation N _ZAP more than the mismatch threshold of the given and stored angles α _PR , and if the position of the normal to the SB working surface N _SB differs from the current specified direction N at an angle α _P over the release threshold α _OTP .

Figure 3 presents the sequence diagram of the formation of a reliable value of the angle sensor, where:

U _P - interference signals;

τ _P1 , τ _P2 ,, τ _P3 , τ _P4 - the duration of the interference causing the angle sensor to fail;

τ ₁ , τ ₂ , τ ₃ , τ ₄ - the duration of the failure of the angle sensor;

T ₁ , T ₂ , T ₃ - intervals following the failure of the angle sensor;

α _ISM - measured angle SB;

U _T - measures of storing the measured values of the angles by the angle sensor SB;

T _D - the period of determining the reliable value of the measured angle;

α _ZAP1 - measured and stored values of the angle sensor at the end of the first intervals for determining reliability;

α _ZAP2 - measured and stored values of the angle sensor at the end of the second intervals for determining reliability;

α _ZAP3 - measured and stored values of the angle sensor at the end of the third intervals for determining reliability;

U _D - the signal of reliability of the measured value of the angle sensor;

α _ACCESS - values of a valid angle of the SB;

α _I1 , α _I2 - the angular values measured by the angle sensor, corresponding to the actual angular positions of the SB;

α _C1 , α _C2 , α _C3 , α _C4 - the angular values measured by the angle sensor, corresponding to the distorted angular positions of the SB;

9, 13, 17, 21, 25 — moments of storing the values of the angle sensor at the end of the first intervals for determining reliability;

α ₉ , α ₁₃ , α ₁₇ , α ₂₁ , α ₂₅ - stored values of the angle sensor at the end of the first intervals for determining reliability;

10, 14, 18, 22, 26 - moments of storing the values of the angle sensor at the end of the second intervals for determining reliability;

α ₁₀ , α ₁₄ , α ₁₈ , α ₂₂ , α ₂₆ - stored values of the angle sensor at the end of the second intervals for determining reliability;

11. 15, 19, 23, 27 - moments of storing the values of the angle sensor at the end of the third intervals of determining reliability;

α ₁₁ , α ₁₅ , α ₁₉ , α ₂₃ , α ₂₇ - stored values of the angle sensor at the end of the third intervals for determining reliability;

12. 16, 20, 24, 28 - moments of determining reliability at the end of the fourth intervals of determining reliability;

_12D α, α _16E, α _20D, α _24D, α _28d - reliable values stored angle detector at the end of the fourth interval determining authenticity.

In figure 3. the formation of a reliable value of the angle sensor α _{ACCESS is} carried out on tacts U _T with a period equal to T _D , with each period T _D divided into 4 equal parts.

At moments 9, 13, 17, 21, 25, the first α _{ZAP1 is memorized} at moments 10, 14, 18, 22, 26 of the second α _zap2 , and at moments 11, 15, 19, 23, 27 of the third α _ZAP3 angular positions of the SB measured angle sensor.

At moments 12, 16, 20, 24, 28, the first, second and third measured values of the angle sensor are compared and the formation of a reliable angle α _ACCESS .

The angular values of α _И1 , α _И2 correspond to the actual angular positions of the SB.

At intervals T ₁ , T ₂ , T ₃ , the angle sensor fails with a duration of τ ₁ , τ ₂ , τ ₃ , τ ₄ caused by interference, respectively, with a duration of τ _P1 , τ _P2 , τ _P3 , τ _P4 , different amplitudes U _P , at this:

-τ _P1 << τ ₁ <T _D , τ _P2 << τ ₂ <T _D , τ _P3 << τ ₃ <T _D , τ _P4 << τ ₄ <T _D ;

- at moments 9, 13, 18 and 23, respectively, the faulty values α _C1 , α _C2 , α _C3 , α _C4 , formed by the angle sensor, are stored;

At time 12, a reliable value of the angle sensor α _12Д = α _{И1 is formed} , since α ₁₀ = α ₁₁ = α _И1 , U _Д = 1, and the faulty value α ₉ = α _{C1 is} ignored.

At time 16, a reliable value of the angle sensor α _16Д = α _{И1 is formed,} since α ₁₀ = α ₁₁ = α _И1 , U _Д = 1, and the faulty value α ₁₃ = α _{С2 is} ignored.

At time 20, a reliable value of the angle sensor α ₀ = α _{И1 is formed,} since α ₁₇ = α ₁₉ = α _И1 , U _Д = 1, and the faulty value α ₁₈ = α _{C3 is} ignored.

At time 24, the reliable value of the angle sensor is stored from the previous cycle α _24Д = α _И1 , since α ₂₁ = α _И1 α ₂₂ = α _И2 , α ₂₃ = α _С4 , that is, α ₂₁ ≠ 022, α ₂₁ ≠ α ₂₃ , α ₂₂ ≠ α ₂₃ , with U _D = 0.

At time 28, a reliable value of the angle sensor α _28Д = α _{И2 is formed} , since α ₂₆ = α ₂₅ = α _И2 , U _Д = 1.

Figure 4 presents a graph of the control of the SB position by the proposed method with the correction of the calculated angle and the corresponding graph of the formation of the signal of reliability of the measured value of the angle sensor, where:

U _D - the signal of reliability of the measured value of the angle sensor;

α _REF - set angle SB;

α _DOS - reliable measured angle SB;

α _RASCH - estimated angle SB;

α _ZAD1 , α _ZAD3 - given angles at the moments of the end of rotation of the SB;

α _ZAD2 , α _ZAD4 - given angles at the moments of the beginning of rotation of the SB;

α _DOST1 , α _DOST2 - reliable measured angles at the moments of the end of rotation of the SB;

α _RASCH1 , α _RASCH2 - design angles at the moments of the end of rotation of the SB;

σ is the angular value of one discrete sector of the angle sensor;

29, 33 - moments of termination of rotation of the SB;

30, 34 - moments of the beginning of rotation of the SB;

31 - moments of termination of the formation of a signal of reliability;

32 - the moment of renewal of the formation of the signal of reliability;

α _PR is the mismatch threshold of a given and stored angles;

α _OTP - angle of release;

Δ ₁ , Δ ₂ - mismatch angles between the calculated and reliable values of the angles.

The diagram in Figure 4 shows changes in a predetermined sequence diagram _SETP α, α _ACCESS valid measured and calculated α _INTS Sa angles.

At the moment 29, the mismatch between the calculated α _REFC = α _REF1 and the given α _REF = α _{REF 1} angles less than the release threshold α _OTP , that is, conditions (14) are satisfied, the rotation of the SB stops.

At time 30, the mismatch between the desired angle α _REF = α _ZAD2 and the stored predetermined angle α _ZAD3 = α _ZAD1 exceeds the threshold mismatch predetermined and stored angles α _PR, i.e., the condition (10), the mismatch between the calculated α _INTS = α _RASCH1 and given α _REF = α _REF2 angles greater than the release threshold α _OTP , that is, condition (12) is satisfied. In addition, at time 30, a validity signal U _Д = 1 and a mismatch Δ ₁ between the calculated α _RASCH = α _RASCH1 and reliable α _ACCESS = α _ACCUE1 angles greater than the value of the discrete sector of the angle sensor σ are _generated , that is, condition (11) is fulfilled. Given the formed conditions at time 30, the calculated angle is corrected, while the calculated angle is corrected by the generated reliable value, that is, α _CALCULATION = α _ACCESS1 . Next, the SB is rotated, during which the calculated angle is calculated according to equation (13).

At the moment 33, a mismatch is reached between the calculated α _REFC = α _RESC2 and the given α _REF3 = α _REF3 angles less than the release threshold α _OTP , that is, conditions (14) are satisfied, the calculation of the calculated angle and the rotation of the SB stops. The absence of a reliable value of the measured angle from moment 31 to moment 32 does not affect the value of the calculated angle.

At moment 34, the value of the mismatch between the current given angle α _REF = α _{REF 4} and the stored predetermined angle α _REF = α _{REF 3} exceeds the mismatch threshold for the given and remembered angles α _OTP , that is, condition (10) is fulfilled, while the mismatch between the calculated α _REFC = α _CALCULATION2 and given α _REF = α _REF4 angles significantly more than the release threshold α _OTP , that is, condition (12) is satisfied. In addition, at time 33, a validity signal U _Д = 1 and a mismatch Δ ₁ between the calculated α _RASCH = α _RASCH2 and reliable α _ACCESS = α _ACCESS2 angles less than the value of the discrete sector of the angle sensor σ are _generated , that is, condition (11) is not satisfied. Given the formed conditions at time 33, the correction of the calculated angle is not performed. Next, the SB is rotated, during which the calculated angle is calculated according to equation (13).

The proposed control method allows us to ensure the correct orientation of the SB during short-term failures of information from the angle sensor caused, for example, by static discharges, due to a comparative analysis of information on the angular position of the SB obtained at different points in time, as well as by reducing the influence of fault values generated by the sensor SB angle by the calculated angle due to the increase in the intervals for the correction of the calculated SB angle by the actual value, and, thus, to provide a current value sufficient for the function nirovaniya airborne equipment that increases the survivability of the spacecraft as a whole.

Information sources

1. Onboard spacecraft control systems. Ed. Doctor of Technical Sciences, prof. A.S. Syrova. M., publishing house MAI-PRINT, 2010, p. 219, 243.

2. Electrostatic discharges on the surface of spacecraft and their impact on the onboard cable network. A.N. Dorofeev. The dissertation for the degree of candidate of technical sciences. M., 2007, p. 25. www.dslib.net/kondensat/jelektrostaticheskie-razrjady-na-poverhnosti-kosmicheskih-apparatov-i-ih-vozdejstvie.html.

3. RF patent 2356788, B64C 1/00, 12/28/2007

Claims (1)

A method of controlling the orientation of the solar battery of a spacecraft with protection against short-term failures of information about the angular position of the solar battery, which consists in determining the predetermined angle of the solar battery as the position of the projection of a unit direction vector onto the Sun on the plane of rotation of the normal to its working surface relative to those associated with the spacecraft coordinate axes, measure the current angle of the solar battery as the angular position of the normal to the working surface of the solar battery in the plane of its rotation Up to a discrete sector of the angle sensor, they calculate the calculated angle as the product of the angular velocity of the solar battery by the time of its rotation, determine the take-off and braking angles, set the release threshold, less than which the mismatch between the set and calculated angles of the solar battery stops, such as:
α _OTP ≈ α _TORM ,
where α _OTP is the release threshold,
they rotate the solar battery in the direction of reducing the mismatch between the calculated and predetermined angles and stop its rotation when the drop threshold is reached, characterized in that they set the angular speed of rotation of the solar battery, which is an order of magnitude or more the angular speed of rotation of the spacecraft around the Earth, remember angle and take the initial value of the calculated angle as a reliable value of the current angle, set the mismatch threshold of the given and stored angles as:
$$\left({\alpha }_{R\mathrm{BUT}3G}+{\alpha }_{T\mathrm{ABOUT}RM}\right)<{\alpha }_{PR}<\arccos \frac{I_{MIN}}{I_{MAX}}$$

,
where α _RAG is the angle of acceleration of the solar battery;
α _TORM - angle of braking of the solar battery;
α _PR is the mismatch threshold of a given and stored angles;
I _MIN - minimum allowable current generated by the solar battery;
I _MAX - the maximum possible current generated by the solar battery,
break the circle of the angle sensor into equal discrete sectors with the value:
(α _RAG + α _TORM ) <σ <α _PR ,
where σ is the angular value of one discrete sector of the angle sensor, take the positions of the bisectors of these discrete sectors corresponding to the values measured by the angle sensor, set the period for determining the reliable value of the current angle by an order of magnitude and more than the maximum duration of the failure of the information received from the angle sensor, and less than the minimum interval of the following failures the specified information, determine the reliable value of the current angle, while each of these periods is divided into four equal time intervals, in At the end of the first, second and third intervals, respectively, the first, second and third measured values of the current angle are stored, and at the end of the fourth interval, the first stored value when it coincides with the second or third stored values, or the second stored value when coincided it with the third one, and they generate a confidence signal, reset the confidence signal if there are no such matches or two of the three stored values do not correspond to the angular positions of the bisse tris of discrete sectors of the angle sensor, if the specified angle differs from the stored predetermined angle at the time of the end of the previous rotation by an amount greater than the mismatch threshold between the specified angles, then the calculated angle is assigned the value of the valid current angle, if the difference between the calculated and valid current angles exceeds the value of the discrete sector of the sensor angle and a confidence signal is generated, while the solar battery is rotated if the mismatch between the calculated and specified angles is more than the release threshold I, and at the moment of reaching the release threshold, they remember the new value of the given angle.

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