RU2465179C1 - Method of spacecraft solar battery orientation by electric current - Google Patents

Abstract

FIELD: transport.

SUBSTANCE: invention relates to electric power supply systems of spacecraft. The method includes presetting the solar battery (SB) design angular rotation velocity exceeding the angular velocity of aircraft circularisation around the Earth by an order and more. In this process, electric current generated by SB is measured, SB rotation period is determined from mismatch between its design and preset angles down in this mismatch. SB is rotated prior to control start up to the moment of starting to reduce achieved greatest amount by means of current. The design SB angle is assigned the value of preset angle, herewith, the design angle is calculated during SB rotation as product of design angular velocity by SB rotation time. Time points of maximum current generation between moments of rotation termination and starting the next rotation are stored in memory. The design angle is corrected for amount of: error correction depending on aircraft angular orbital velocity, stored in memory time values at the moment of SB rotation termination and at the moment when current generated by SB reaches maximum value, as well as on SB rotation period. Design angle is increased or decreased by error correction value when SB is rotation during time reckoning in direction of increasing or decreasing angle respectively.

EFFECT: method functionality enhancement while providing correct SB orientation by generated by it current in the absence of information about SB angular position.

5 dwg

Description

The invention relates to power supply systems for spacecraft (SC) with solar panels (SB).

Power supply of the spacecraft onboard equipment throughout the entire spacecraft operation is carried out using the SB. In the absence of sufficient current necessary for the operation of the onboard equipment, for example, in the shadow section of the orbit, the spacecraft’s onboard equipment can be supplied with electric power for a limited time from the batteries, which were recharged by the current generated by the SB in the illuminated section of the orbit.

The magnitude of the current generated by the SB depends on the orientation of the plane of its working surface relative to the Sun or other radiation source. To increase the efficiency of the SB, on-board automatic control systems (BASU) are used, which include SB rotation devices made on the basis of electromechanical drives (EMF) with sensors mounted on the output shaft.

The control algorithms of modern spacecraft are implemented in the form of software in the on-board computers included in the BASU. Using these programs, information from the corresponding sensors installed onboard the spacecraft is processed, and tasks related to determining the position of the spacecraft in space, controlling its position and movement in a given orbit, as well as controlling the onboard equipment included in it, are solved . One of the tasks solved in BASU is the management of the situation of the Security Council. Using the software of the motion control system (SUD), the direction to the Sun relative to the coordinate axes associated with the spacecraft is determined and the specified angle for the SB position control software is generated. In the event of a mismatch between the generated predetermined and the current angular position of the SB over the threshold, the SB position control software generates commands to rotate the SB in the direction of decreasing this discrepancy, which are received from the BASU output to the SB rotation device. After reducing this mismatch to the drop threshold, the SB position control software generates commands to stop the rotation of the SB.

The closest technical solution is the SB orientation method, which consists in determining the predetermined angle of the solar battery relative to the coordinate axes associated with the spacecraft as the position of the projection of a unit direction vector onto the Sun on the plane of rotation normal to the working surface of the solar battery, and determining the angular rotation speed of the solar battery calculate the calculated angle of the solar battery as the product of the angular velocity by the time of its rotation, determine the acceleration angle as the magnitude of the change the angular position of the normal from the moment of issuing the command to start the rotation when the mismatch between the set and calculated angles until the steady-state angular velocity is reached, the braking angle is determined as the change in the angular position of the normal from the moment the command was issued to stop rotation at the end of the mismatch until the rotation ceases completely, set the response threshold, upon reaching which a mismatch is formed between the specified and calculated angles, set the release threshold, upon reaching where the mismatch between the set and calculated angles of the solar battery stops, less than the threshold, take the acceleration, braking and release thresholds equal to each other, rotate the solar battery in the direction of decreasing the mismatch along the shortest path between the set and calculated angles [1].

As a rule, the position of the SB is controlled using feedback from the sensor of the angular position of the output shaft of the EMF SB. During the spacecraft flight in a given orbit, prolonged electromagnetic interference or electrostatic discharges may occur, which can lead to information malfunctions from this sensor. In addition, during operation, failures may occur in the angle sensor, as well as in BASU devices or communication lines through which the information on the angular position of the SB is transmitted. The indicated failures and failures can lead to improper orientation of the SB, which in turn leads to a decrease in the power supply of on-board equipment and, ultimately, to disruptions in the performance of tasks performed on board the spacecraft.

The technical task of the invention is to expand the functionality of the known method of orientation of the SB in order to ensure the correct orientation of the solar battery formed by its current in the absence of information about its angular position.

The specified technical result is achieved by the fact that in the known method of orientation of the solar battery of a spacecraft, which consists in determining the predetermined angle of the solar battery relative to the coordinate axes associated with the spacecraft as the position of the projection of a unit direction vector onto the Sun on the plane of rotation of the normal to the working surface of the solar battery determine the angular velocity of rotation of the solar battery, calculate the calculated angle of the solar battery as the product of the angular velocity by its time rotation, determine the acceleration angle as the change in the angular position of the normal from the moment the command was issued at the beginning of rotation when a mismatch between the set and calculated angles until the steady angular velocity is reached, the braking angle is determined as the change in the angular position of the normal from the moment the command was issued to stop rotation at the end of the mismatch until the rotation is completely stopped, the response threshold is set, upon reaching which the mismatch between the given and calculated angles, set the release threshold at which the mismatch between the set and calculated angles of the solar battery is stopped, less than the threshold, take the acceleration, braking and release thresholds equal to each other, rotate the solar battery in the direction of reducing the mismatch along the shortest path between the given and calculated angles, additionally determine the period of a full revolution, the direction and angular velocity of rotation of the spacecraft around the Earth in a circular orbit, specify the angular velocity the rotation speed of the solar battery, which exceeds the angular velocity of rotation of the spacecraft around the Earth by an order of magnitude or more, determines the maximum possible and minimum allowable currents generated by the solar battery, divide the circle of rotation of the normal to the working surface of the solar battery into equal angular sectors, greater than the sum of the acceleration angles and braking and less than the arc cosine, the ratio of the minimum allowable and maximum possible currents generated by the solar battery, and the bisector of the zero sector sensor and the angle corresponds to the zero angular position of the above projection of the unit vector, the period of rotation of the solar battery is determined as the ratio of the time of a full revolution of the spacecraft around the Earth to the number of angular sectors of the normal circle of rotation, the time of the rotation of the solar battery for one rotation period is determined as the ratio of the value of one angular sector to the angular velocity of the solar battery, set the response threshold of not more than half of one angular sector, assign values equal to the angular the position of the bisector of the angular sector, within the boundaries of which there is the angular position of the projection of the unit direction vector to the Sun, before starting control, rotate the solar battery clockwise or counterclockwise, measure the current produced by it, stop the rotation of the solar battery after it begins to reduce the achieved current of the highest value, assign the calculated the angle of the solar panel, the value of the specified angle, during control by the mismatch between the given and calculated angles in sequence, remember the moments the time of termination of rotation, when the current generated by the solar battery reaches its maximum value and the beginning of the next rotation, if the current generated by the solar battery decreases to less than the minimum allowable value, or when the maximum value of the generated current at the time of the end or beginning of the next rotation is reached, the value of the calculated angle is changed after the end of the said next rotation by

Δα = ω _O · (t _ZAP2 -t _ZAP1 -0.5 · T _SB ),

where Δα is the correction to the calculated angle, ω _О is the angular orbital velocity of the spacecraft, t _ZAP1 is the stored value of the countdown time at the moment of formation of the command to stop rotation, t _ZAP2 is the stored value of the countdown time at the moment the current generated by the solar battery reaches its maximum value, T _SB - the period of rotation of the solar battery, increase or decrease the calculated angle by the amount of correction during rotation of the solar battery during the countdown, respectively, in the direction of increasing or decreasing the angle.

Figure 1 shows the position of the spacecraft in orbit of the Earth, figure 2 - the dependence of the current generated by the SB, from the angular position of the SB relative to the direction to the Sun, figure 3 - the time dependence of the angular position of the SB and the current generated by it when the calculated and actual 4 and 5 are the time dependences of the angular position of the SB and the minimum permissible current generated by it when the calculated and actual angles are mismatched, respectively, less than and more than half of one sector of the circle of rotation of the SB.

The proposed method is implemented as follows.

At the stage of ground preparation of the spacecraft for launch, the direction of motion and the angular velocity of rotation of the spacecraft in orbit around the Earth are determined. To control the orientation of the SB, an EMF is used with a fixed at its output SB with a steady angular rotation speed of an order of magnitude and more than the angular velocity of rotation of the spacecraft around the Earth, that is

where ω _О is the angular velocity of the spacecraft rotation around the Earth;

ω _SBU is the steady angular velocity of the SB.

By passport data or by the results of experiments at the stands determine:

- the value of the steady angular velocity of rotation of the output shaft of the EMF SB;

- SB acceleration angle, as the magnitude of the change in the angular position of the normal to the SB working surface, starting from the moment the mismatch between the set and calculated angles begins, at which a rotation command is generated until the SB reaches a steady angular velocity;

- braking angle, as the magnitude of the change in the angular position of the indicated normal from the moment the mismatch between the set and calculated angles ceases, as a result of which a command is formed to stop the rotation of the SB until its rotation stops completely;

- the maximum possible value of the current that the SB can generate;

- the minimum allowable current that the SB must generate to ensure the functioning of the spacecraft onboard equipment.

The steady-state angular velocity of the SB is taken as the calculated one, i.e.

where ω _SB - the estimated angular velocity of SB.

Divide the circle of rotation of the SB into equal angular sectors, i.e.

where σ is the angular value of the sector of the circle of rotation of the SB;

n is an integer.

In this case, the angular value of the sector should be in the range

where α _Razg - SB acceleration angle;

α _TORM - angle of braking SB;

I _MAX - the maximum possible current generated by the SB;

I _MIN - minimum allowable current SB.

The bisector of the zero angular sector must correspond to the zero angular position of the projection of the unit direction vector on the Sun onto the plane of rotation of the normal to the working surface of the SB relative to the coordinate axes connected to the spacecraft.

Determine the rotation period of the SB, as

where T _O is the period of a full revolution of the SC around the Earth;

T _SB - period of rotation of the SB.

In the process of controlling the orientation of the SB determine the angle between the set and calculated angles of the SB, as

where Δ _α is the angle between the specified and calculated angles of the SB;

α _SB - estimated angle SB;

α _REF - set angle SB.

The release threshold is set as the angle between the set and calculated angles of the SB, upon reaching which the mismatch ceases and a command is formed to stop the rotation of the SB, while the release threshold, as well as the acceleration and braking angles, are taken equal to each other, i.e.

where α _OTP is the release threshold.

The response threshold is set as the angle between the set and calculated angles of the SB, upon reaching which a mismatch appears and a command is formed to start the rotation of the SB in the range

where α _СР - response threshold.

After the launch of the spacecraft into a given circular orbit, the current produced by the SB begins to be measured. At the same time, using the algorithms of the ACS, they continuously determine the angular position of the projection of a unit direction vector on the Sun onto the plane of rotation of the normal to the SB working surface relative to the coordinate axes associated with the SC.

Before starting control, an initial setting of the SB position is made, and a command is issued to rotate the SB in one direction clockwise or counterclockwise. At the moment of reaching the highest current and the beginning of its decrease, to a value, for example, ~ 90% of the achieved maximum value, a command is issued to stop the rotation of the SB. After that, the calculated angle of the SB set the value of the angular position of the projection of the unit direction vector on the Sun

where α _SB - the estimated angular position of the SB;

α _СБN is the angular position of the projection of a unit direction vector onto the Sun on the plane of rotation of the normal to the working surface of the SB relative to the coordinate axes associated with the spacecraft.

The predetermined angle is determined as the angular position of the bisector of the sector, within the boundaries of which there is the angular position of the projection α _СБN , i.e.

where α _ZAD - a given angle SB;

i is the number of the angular sector of the circle of rotation of the SB.

At the moment of the appearance of a mismatch between the set and calculated angles of the SB, at least the response threshold rotates it along the shortest path in the direction of decreasing the angle between them, giving the appropriate rotation command, i.e.

At the moment of the termination of the mismatch between the set and calculated angles of the SB, not more than the release threshold, its rotation is stopped, giving the appropriate command to stop the rotation, that is, when

During the rotation of the SB, from the beginning to the moment the mismatch ceases, the calculated angle is calculated as

where j is the step of changing a given angle (integer);

α _j - the angular position of the SB at the start of rotation at the j-th step of changing the specified angle;

α _{j + 1} is the angular position of the SB after the end of rotation at the jth step of changing the specified angle;

t _j is the SB rotation time at the jth step of changing a given angle;

ω _SB - the estimated angular velocity of rotation of the SB.

During the flight of the spacecraft in a circular orbit, the position of the normal α _СБN changes uniformly and continuously, while the specified angle in accordance with equation [10] increases or decreases discretely in increments of one sector. In the case of changing the specified angle by one sector, a mismatch appears and the SB starts rotation, and the calculated angle of the SB is calculated in accordance with equation [13].

After the termination of the mismatch, the calculated angle reaches the value of the specified angle and, thus, changes by the value of one sector.

When rotating in the direction of increasing a given angle, the position of the SB after the end of rotation can be determined as

Remember the time of the termination of rotation of the SB

where t _ZAP1 - the stored value of time at the time of termination of rotation of the SB;

t _TEK - current time.

The moment of time when the current generated by the SB is reached reaches its maximum value in the time interval from the time it stops to the moment the SB starts a new rotation

where t _ZAP2 is the stored value of time at the moment the current reaches its maximum value;

I _SB - the current value of the generated SB current;

I _NCj is the largest current value from the moment the jth terminates to the moment of the beginning of the (j + 1) th rotation of the SB.

Remember the time moment of the beginning of the new (j + 1) -th rotation of the SB

where t _ZAP3 is the stored value of time at the beginning of a new (j + 1) -th rotation of the SB.

If the current generated by the SB reaches its maximum value at the moments of the end or beginning of the next rotation, or reaches a value less than the minimum allowable at any given time, i.e.

Given that, in accordance with equation [5], the time moment of the beginning of the next (j + 1) -th rotation differs from the moment of the end of the jth rotation by the value of the rotation period of the SB

The correction to the calculated angle is calculated as

where Δα is the correction to the calculated angle.

If the angular position of the projection α _СБN and, accordingly, the rotation of the SB was carried out at the (j + 1) -th rotation in the direction of increasing the angle, then the calculated angle after the end of rotation is increased by the amount of correction, i.e.

If the angular position of the projection α _СБN and, accordingly, the rotation of the SB was carried out at the (j + 1) -th rotation in the direction of decreasing the angle, then the calculated angle after the end of rotation is reduced by the amount of correction, i.e.

The proposed method for orienting the SB of the spacecraft in current can be implemented using BASU algorithms and means of the ground control complex (GCC). At the moments of the beginning and end of the rotation of the SB, the telemetry information collected onboard the spacecraft is transmitted by means of communication to the NKU. The specified information contains time-related data on the angular position of the projection of a unit direction vector onto the Sun, the set and calculated angles of the SB, as well as information about the value of the current generated by the SB. Commands are sent from the NKU to set the SB in the initial position, as well as the values of the angle corrections to the calculated angle.

Figure 1 presents the position of the spacecraft in orbit of the Earth, where:

1 - Earth;

2 - spacecraft orbit;

3 - radiation from the sun;

4 - shadow area of the orbit;

5 - conditional image of the spacecraft at the time of the end of the rotation of the SB;

6 - the position of the spacecraft at the time of the middle of the time interval between rotations of the SB;

7 - the position of the spacecraft at the start of the next rotation of the SB;

8 - solar battery;

N ₁ , N ₂ , N ₃ - projections of unit direction vectors to the Sun on the plane of normals rotation to the working surface of the SB relative to the coordinate axes associated with the spacecraft at positions 5, 6, 7 of the spacecraft;

X, Y, Z - coordinate axes associated with the spacecraft:

X - axis of the spacecraft along the yaw channel,

Y - axis of the spacecraft along the roll channel,

Z - axis of the spacecraft along the pitch channel;

ω _О - angular velocity of rotation of the spacecraft around the earth;

ω _SB - the estimated angular velocity of rotation of the SB;

N _SB1 , N _SB2 , N _SB3 - the current normal position to the working surface of the SB at the moments of the end of rotation, the middle of the time interval between rotations and at the time of the start of the next rotation of SB, respectively;

Δα _SB1 - the angular deviation of the normal to the working surface of the SB from the direction of projection of a unit direction vector onto the Sun onto the plane of its rotation, corresponding to the position of the SB at the time of the normal lag from the projection to half the sector;

Δα _SB2 - zero deviation of the normal to the working surface of SB from the direction of projection of a single vector on the Sun;

Δα _SB3 is the angular deviation of the normal to the working surface of the SB from the direction of projection of a unit direction vector onto the Sun onto the plane of its rotation, corresponding to the position of the SB at the time of the advance of the normal direction of the projection to half the sector.

Figure 1 shows three positions 5, 6, 7 of the spacecraft, which it can occupy during a flight in a circular orbit 2 of Earth 1. At the same time, it rotates with the orbital angular velocity ω _О , counterclockwise. The X axis (yaw) of the X, Y, Z coordinate axes associated with the SC is directed from the center of the Earth. A solar battery 8 is installed onboard the spacecraft (in the spacecraft 6 position, the axis of rotation of which coincides with the Z axis (pitch), while the plane formed by the normal rotation to the working surface of SB SB N _SB1 , SB _SB2 , _SB3 N (in the CA _5,6 positions , 7), parallel to the plane formed by the X (yaw) and Y (roll) axes of the coordinate axes associated with the SC, which is parallel to the orbit plane 2. Projections of the unit direction vector on the Sun N ₁ , N ₂ , N ₃ on the plane formed by the rotation of the normal to the working surface N _SB1 , N _SB2 , N _SB3 (in the positions of the spacecraft 5, 6, 7), directed towards radiation from the Sun 3. During a flight in Earth’s orbit, the spacecraft periodically enters the shadow portion of orbit 4. During the flight, the SB rotates periodically, and when the threshold is reached, the SB starts rotation around the Z axis (pitch) with an angular velocity ω _{SB of} an order of magnitude or higher the spacecraft’s angular velocity of rotation ω _О around the Earth, when the threshold for releasing is reached, the SB stops rotation.

In the position of KA 5, the direction of the normal to the working surface of SB _{SB1 is shown} at the moment of termination of its rotation. Moreover, the mismatch between the projection N ₁ and the normal N _SB1 corresponds to the angle Δα _SB1 . In the indicated position, the normal to the working surface of SB N _{SB1 is} ahead of the projection position of a unit direction vector onto the Sun N.

In the position of spacecraft 6, the position of the normal to the working surface of SB N _{SB2 is shown} , which coincides with the position of the projection of a unit direction vector on the Sun N ₂ . Moreover, the mismatch between the projection N ₂ and the normal N _SB2 corresponds to the zero value of the angle, that is, Δα _SB2 = 0. SB in this position produces the greatest current.

In the position of the spacecraft 7 shows the direction of the normal to the working surface SB N _SB3 at the beginning of its rotation. Moreover, the mismatch between the projection N ₃ and the normal N _SB3 corresponds to the angle Δα _SB3 . In this position, the normal to the working surface of SB N _SB3 lags behind the projection position of a unit direction vector on the Sun N ₃ .

Figure 2 shows the dependence of the current generated by the SB, on the angular position of the SB relative to the direction to the Sun, where:

9 - circle of rotation of the SB;

10 - the position of the SB at the time of lagging from a given angle by half the sector;

11 - the position of the SB at the time of advancing a given angle by half the sector;

12 - SB position at the moment of deviation from the direction to the Sun by an amount corresponding to the minimum current value;

13 - the position of the SB at the time of deviation from the direction to the Sun by an amount corresponding to the current value less than the minimum acceptable to ensure the operability of onboard equipment;

N is the projection of a unit direction vector to the Sun on the plane of rotation of the normal to the working surface of the SB relative to the coordinate axes associated with the spacecraft;

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

σ is the angular value of one sector of the circle of rotation of the SB;

I _SB - current generated by SB;

Δα _SB - the magnitude of the angular mismatch between the direction of the normal to the working surface of the SB and the projection of a unit direction vector on the Sun on the plane of its rotation;

I _SB1 , I _SB3 - currents generated by the SB corresponding to deviations of the SB from the direction to the Sun by half of the sector;

I _SB2 - the highest current generated by the SB when the normal to the working surface of the SB coincides with the direction to the Sun;

I _MIN - the minimum allowable current that the SB must generate to ensure the operability of on-board equipment;

I _SB4 - current, less than the minimum permissible to ensure the on-board equipment operability;

Δα _SB1 - the angular deviation of the normal to the working surface of the SB from the direction of projection of a unit direction vector onto the Sun onto the plane of its rotation, corresponding to the position of the SB at the time of the normal lag from the projection to half the sector;

Δα _SB2 - zero deviation of the normal to the working surface of SB from the direction of projection of a single vector on the Sun;

Δα _SB3 — the angular deviation of the normal to the working surface of the SB from the direction of projection of a unit direction vector onto the Sun onto the plane of its rotation, corresponding to the position of the SB at the time of the advance of the normal direction of the projection to half the sector;

Δα _MIN is the angular deviation of the SB from the direction to the Sun, corresponding to the position of the SB at the moment of generation of the minimum allowable current;

Δα ₄ - the angular deviation of the SB from the direction to the Sun at the time of generation of the current is less than the minimum allowable.

Figure 2 shows the dependence of the current I _SB generated by the SB on the mismatch angle Δα between the normal to the SB working surface and the projection of a unit direction vector on the Sun N onto its rotation plane. During the flight of the spacecraft in a given orbit, the SB periodically rotates with an angular velocity ω _SB , while the normal to its working surface changes its position relative to the center of circle 9 by an angle equal to the value of one sector σ. At position 10, this normal lags behind the projection position N by half the sector σ, that is, Δα _SB1 = -0.5 · σ, which corresponds to the current I _SB1 generated by the SB. When the normal coincides with the projection of the direction vector on the Sun N, that is, when Δα _SB2 , SB produces the largest current I _SB2 . At position 11, the normal to the SB working surface is ahead of the position of the projection of the direction to the Sun by half the sector σ, that is, Δα _SB3 = + 0.5 · σ, which corresponds to current I _SB3 . At position 12, the normal to the SB working surface is ahead of the position of the projection of the direction to the Sun by a value corresponding to the minimum permissible current value I _MIN . In position 13, the normal to the SB working surface is ahead of the position of the projection of the direction to the Sun at an angle Δα _SB4 corresponding to the current value I _SB4 less than the minimum acceptable.

Figure 3 presents the time dependence of the angular position of the SB and the current generated by it with the coincidence of the calculated and actual angles, where:

14-20 - time instants t of a change in the state (or position ??) of the SB:

14, 16, 18, 20 - time points corresponding to deviations of the SB from the direction to the Sun by half of the sector;

15, 17, 19 - time points corresponding to the coincidence of the normal to the working surface of the SB with the direction to the Sun;

α _СБN - the angular value of the projection of a unit direction vector onto the Sun on the plane of rotation of the normal to the working surface of the SB relative to the coordinate axes associated with the SC;

α _REF - set angle SB;

α _SBP - the actual angle of SB;

α _RBU - estimated angle SB;

σ - sectors of the circle of rotation of the SB;

I _SB11 — current generated by the SB when the normal position to the SB working surface lags behind the direction to the Sun by half the angular sector σ;

I _SB12 - the highest SB current, when the normal to the SB working surface coincides with the projection of the direction to the Sun on the plane of its rotation;

I _SB13 — current generated by the SB when ahead of the normal to the working surface of the SB direction to the Sun by half the angular sector σ;

I _MIN - minimum permissible current;

T _SB - period of rotation of the SB;

Δτ is the rotation time of the SB;

α _SB11 , α _SB12 , α _SB13 , α _SB14 , α _SB15 - angles corresponding to different positions of the SB.

In the embodiment shown in FIG. 3, the calculated α _SB and the actual α _{SBF, the} angular positions of the SB approximately coincide. The angular position of 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 α _СБN changes in the direction of increase. When the projection α _{СБN reaches the} corresponding angular values of I _СБ11 and I _СБ13 , at times 14 and 18, the specified angle α _REF changes by the value of the angular sector σ. At time 14 SB generates current I _SB11 , while the specified angle α _ZAD changes its value from α _SB11 to α _SB13 . The mismatch between the given α _RH and the calculated α _{SB SB} corners at the moment of change reaches the threshold, after which SB starts moving from position α _SB11 to position α _SB13 . At the point in time corresponding to point 15, the angular position of the projection of the unit direction vector onto the Sun, α _SBN coincides with the calculated α _SB and the actual α _SBF angles, i.e., α _SBN = α _SB = α _SBF = α _SB12 , while the SB produces the highest current I _SB12 , and at time 16 - the minimum current I _SB13 . From moment 16 to moment 18, the angular position of the projection α _СБN changes by the value of the angular sector σ from angle α _СБ13 to angle α _СБ14 . At time 17, the angular position of the projection α _SBN , the estimated α _SB and the actual α _{SBP, the} angular positions of the SB coincide, while the SB produces the largest current I _SB12 . At time 18 SB begins rotation from position α _SB13 to position α _SB14 at point 20, while at point 19 at the moment of reaching angle α _SB15 SB generates the highest current I _SB12 .

Thus, the angular position of the projection α _SBN is shifted by the value of one angular sector σ for one period of rotation of the SB TSB, which can be determined as

The actual angular position of the SB α _SBP is shifted by the value of one angular sector σ during the rotation time of the SB Δτ, which can be determined as

where Δτ is the rotation time of the SB;

ω _SB - the estimated angular velocity of SB.

In accordance with inequality (1), the angular velocity of rotation of the SB SB ω _{SB is} an order of magnitude or more higher than the orbital angular velocity of the spacecraft ω _O , therefore, the time of rotation of the SB Δτ in the calculations can be ignored. Thus, during one period of rotation of the SB from moment 16 to moment 18, the highest current I _{SB12 is} generated at time 17, approximately in the middle of the rotation period of SB T _SB .

Figure 4 presents graphs of the correspondence of the angles and current generated by the SB, at which it reaches the minimum acceptable value when the calculated and actual angles are less than half of one sector of the circle of rotation of the SB.

Figure 4 presents the time dependence of the angular position of the SB and the minimum allowable current generated by it when the calculated and actual angles are less than half of one sector of the circle of rotation of the SB, where:

α _СБN - the angular position of the projection of a unit direction vector onto the Sun on the plane of rotation of the normal to the working surface of the SB;

α _REF - the specified angular position of the SB;

α _SBP - the actual angular position of the SB;

α _SB - the estimated angular position of the SB;

21-29 - moments of time t changes in the provisions of the SB;

21, 26 - time points corresponding to the principles of rotation of the SB;

23, 28 - time points corresponding to the ends of the rotation of the SB;

22, 25, 27 - time points corresponding to coincidences of the normal to the working surface of the SB with a direction to the Sun;

29 is a point in time correction of the calculated angle;

σ is the angular value of one sector of the circle of rotation of the SB;

I _SB21 - current generated by the SB at the time the rotation begins;

I _SB22 - maximum current generated by the SB, corresponding to the coincidence of the normal to the working surface of the SB with the projection of the direction to the Sun on the plane of its rotation;

I _SB23 - current generated by SB at the end of rotation;

I _MIN - minimum permissible current;

T _SB - period of rotation of the SB;

Δτ is the rotation time of the SB;

Δα _SB1 - the mismatch between the actual and estimated angular position of the SB before correction;

α _ZAD21 , α _ZAD22 , α _ZAD23 - set and calculated angular positions of the SB;

α _SB21 , α _SB22 , α _SB23 , α _SB24 , α _SB25 - the actual angular position of the SB.

Figure 4 current produced Sa reaches a value below the minimum value I _MIN at the time of stopping the rotation, the calculated angular lagging Sa _Sa α position of the actual α value Δα _{SBF SB2} at least half the angular sector σ, i.e. at _SB2 Δα < 0.5 In the given example, the angular position α _{СБN of the} projection of a unit direction vector on the Sun changes its value in the direction of increasing the angle. At time 21 Sa produces α _SB21 current, wherein the predetermined angle α _REF changes by one sector σ from the value α _ZAD21 to α _ZAD22, at the same time the angle error between the calculated α _Sa and specify α _SETP angles begins to exceed the threshold α _CP , in connection with which a team is formed and the SB starts rotation in the direction of increasing the angle. During rotation, the actual angular position of the SB α _SBF changes from α _SB21 at 21 to α _SB23 at 23, in which the SB produces a minimum current value I _SB23 , less than the minimum allowable value I _MIN . During rotation at time 22 SB, the maximum current I _{SB22 is generated} , since the given α _REF and actual α _SBF angles coincide, which corresponds to the angular position α _SB22 . After reaching at the moment 23 the actual angle α _{SBF, the} value Iα _SB23 up to the moment 26, the calculated angular position of the SB α _{SB is} behind the actual α _SBP by the discrepancy Δα _SB1 . During the time interval from moment 23 to moment 26, the angular position of the projection α _СБN changes by the value of one angular sector σ.

At the time 23 of the end of the rotation of the SB, the time value is stored, i.e.

where t _ZAP1 is the stored time at the end of the rotation of the SB;

t ₂₃ is the time corresponding to the moment of the end of rotation 23.

After that, the SB current is measured and the moment of time 25 corresponding to the achievement of the highest current value I _SB22 , which is generated at the moment of coincidence of the projection angle α _SBN and the actual angle α _SBF , is _recorded as

where t _ZAP2 is the stored value of the coincidence time of the angular position of the projection and the actual angle;

t ₂₅ is the time corresponding to the moment the current reaches its maximum value.

Given the uniform, linear nature of the change in the angular position of the projection α _SBN , the set and calculated angles coincide in the middle of the rotation period of the _{SBT SB} , while the rotation time Δτ SB in the calculations can be ignored in accordance with equations (1, 23, 24). Next, the difference Δt _{SB1 is determined}

where Δt _SB1 is the difference between the stored time values;

t ₂₅ is the time corresponding to time 25;

t ₂₃ is the time corresponding to time 23;

T _SB - period of rotation of the SB.

The angular correction Δα _SB1 , on which it is necessary to adjust the calculated angular position of SB _{SB SB} , is calculated as

where Δα _SB1 is the angular correction to the calculated angle;

ω _O is the angular orbital velocity of the spacecraft;

Δt _SB1 - the difference between the stored values of time at moments 25 and 24.

At time 29, the calculated angle α _{SB is} adjusted by the correction value Δα _SB1 , while its value becomes approximately equal to the value of the actual angle, i.e.

where α _{RRF (j)} is the value of the calculated angle before adjustment;

α _{RRF (j + 1)} - value of the calculated angle after adjustment;

Δα _SB1 - angular correction to the calculated angle;

α _SBF is the actual angle.

After correcting the calculated angle in subsequent periods of rotation of the SB, the graphs of the angles and current generated by the SB will correspond to Fig. 3.

Figure 5 presents graphs of the correspondence of the angles and current generated by the SB, at which the current reaches the minimum acceptable value when the calculated and actual angles are more than half of one sector of the circle of rotation of the SB.

Figure 5 shows the time dependences of the angular position of the SB and the minimum allowable current generated by it when the calculated and actual angles are more than half of one sector of the circle of rotation of the SB, where:

α _SBN - the angular position of the projection of a unit direction vector onto the Sun on the plane of rotation of the normal to the SB working surface;

α _REF - the specified angular position of the SB;

α _SBP - the actual angular position of the SB;

α _SB - the estimated angular position of the SB;

30-35 - moments of time t changes in the state (or position ??) SB:

30, 33 - time points corresponding to deviations of the SB from the direction to the Sun at the moments of the beginning of rotation of the SB;

31, 34 - time points corresponding to deviations of the SB from the direction to the Sun at the moments when the rotation of the SB ends;

35 - the moment of correction of the calculated angle;

σ is the angular value of one sector of the circle of rotation of the SB;

I _MAX - maximum current generated by the SB, corresponding to the coincidence of the normal to the working surface of the SB with the projection of the direction to the Sun on the plane of its rotation;

I _MIN - the minimum required current value to ensure the operability of on-board equipment;

I _SB31 - the current generated by the SB at the time of the start of rotation;

I _SB32 - current generated by the SB at the end of rotation;

T _SB - period of rotation of the SB;

Δτ is the rotation time of the SB;

Δα _SB2 - the mismatch between the actual and estimated angular position of the SB before correction;

Δα _SB3 - the mismatch between the actual and estimated angular position of the SB after correction;

α _ZAD31 , α _ZAD32 , α _ZAD33 - specified angular position of the SB;

α _SB31 , α _SB32 , α _SB33 , α _SB34 - the actual angular position of the SB.

In Fig. 2, the current generated by the SB reaches its maximum value at the start of rotation when the calculated angular position of the SB α _{SB falls behind the} actual α _SBF by Δα _SB2 more than half of the angular sector σ, i.e., when Δα _SB2 > 0.5 · σ . In this case, the minimum permissible current value is not achieved. At time 30, the specified angle α _ZAD changes from α _SB31 to α _SB32 , and at time 33, from α _SB32 to α _SB33 , there is a mismatch between the given α _ZAD and the calculated α _SB angles by more than the threshold, that is, inequality condition (12). At the same time, a command is issued, after which the SB starts rotation. Upon reaching the drop thresholds, in accordance with equation (13) at moments 31 and 34, respectively, the SB stops rotation. Prior to the start of rotation at moments 30 and 33, the value of the calculated angle α _SB approximately coincides with the given α _RH , which corresponds to the angular values α _RH31 and α _RH33 . After the rotation of the SB, at moments 31 and 33, it approximately coincides with the values of the given angle α _ZAD32 and α _ZAD33, respectively. Actual angles α _SBF at moments 30 and 33, before the start of rotation of the SB, are respectively equal to the values of α _SB31 and α _SB32 , and at moments 31 and 33, after the end of rotation, are _{equal to the} values of α _SB32 and α _SB33 . At time 32, the calculated angle α _SB coincides with the given α _RH and is equal to α _{RH 31} , while at time 33, which coincides with the beginning of rotation of the SB, the highest current value I _{SB31 is generated} , less than the maximum possible I _MAX . The mismatch between the actual and the given angles in the time range 31-33 has a fixed value Δα _{SB2 of} more than half of the angular sector σ. At the end of rotation of the SB, a current I _{SB32 is generated} that does not reach the minimum allowable value of I _MIN . Given that the value of the rotation time of the SB Δτ can be neglected, the difference Δt _SB2 between the stored values of time at moments 33 and 32 is

where Δt _SB1 is the difference between the stored values of time, t ₃₃ is the time corresponding to time 33, t ₃₂ is the time corresponding to time 32, T _SB is the rotation period of SB. At time 35, the calculated angle d _{SB is} adjusted by the correction value Δα _SB2

where α _{SB (j)} is the value of the calculated angle before adjustment;

α _{SB (j + 1)} - value of the calculated angle after adjustment;

Δα _SB2 - angular correction to the calculated angle.

If during the subsequent period of rotation of the SB there is a current value generated by the SB less than the minimum allowable value of I _MIN , or the current reaches its maximum value at the time of issuing a command to rotate or to stop rotation of the SB. Accordingly, in the event of a termination or occurrence of discrepancies between the set and calculated angles, the above steps are repeated, by memorizing the time points and adjusting the calculated angle. They stop performing the indicated actions related to the adjustment of the calculated angle if the current generated by the SB does not decrease less than the minimum acceptable value, and the maximum current value is achieved in the time interval between the rotations of the SB.

It should be noted that as a result of the impact of various external factors on the control equipment and the surface of the SB during the spacecraft’s flight on the control equipment and the surface of the SB: radiation, temperature drops, micrometeorites, static charges, and others, a decrease in the effectiveness of the SB is observed over time, the result of which is a decrease in current. In addition, the greatest current generated by the SB can change over time due to the gradual change in the position of the plane of rotation of the normal to the working surface of the SB relative to the plane of the orbit. The proposed method allows us to ensure the correct orientation of the SB of the spacecraft on the Sun in current, without using information about the angular position of the SB from the angle sensor, in case of failures or failures, as well as in the case of a change in the position of the plane of rotation of the normal to the working surface of the SB relative to the plane of the orbit with time, which increases survivability and extends the life of the control system for the position of the SB, and therefore the spacecraft as a whole.

Information sources

1. RF patent RU 2356788 C1, B64C 1/00, 12/28/2007

Claims (1)

The method of orientation of the solar battery of the spacecraft but the current, which consists in determining the specified angle of the solar battery relative to the coordinate axes associated with the spacecraft as the position of the projection of a unit direction vector onto the Sun on the plane of rotation normal to the working surface of the solar battery, determine the angular velocity of rotation of the solar battery calculate the calculated angle of the solar battery as the product of the angular velocity by the time of its rotation, determine the acceleration angle as the magnitude of the change in the normal position from the moment of issuing the command to start rotation when the mismatch between the set and calculated angles is formed until the steady angular velocity is reached, the braking angle is determined as the change in the angular position of the normal from the moment the command was issued to stop rotation at the end of the mismatch until the rotation is completely stopped, set the response threshold, upon reaching which a mismatch is formed between the specified and calculated angles, set the release threshold, upon reaching and which the mismatch between the set and calculated angles of the solar battery stops, less than the threshold, take the acceleration, braking and release thresholds equal to each other, rotate the solar battery in the direction of reducing the mismatch along the shortest path between the set and calculated angles, characterized in that the period is determined of a full revolution, the direction and angular velocity of rotation of the spacecraft around the Earth in a circular orbit, specify the angular velocity of rotation of the solar battery, exceeding by the core and the more angular velocity of rotation of the spacecraft around the Earth, determine the maximum possible and minimum allowable currents generated by the solar battery, divide the circle of rotation of the normal to the working surface of the solar battery into equal angular sectors of more than the sum of the acceleration and deceleration angles and less than the arc cosine of the ratio of the minimum and the maximum possible currents generated by the solar battery, and the bisector of the zero sector of the angle sensor corresponds to a zero angular position above shown projection of a single vector, determine the rotation period of the solar battery, as the ratio of the time of a full revolution of the spacecraft around the Earth to the number of angular sectors of the normal rotation circle, determine the rotation time of the solar battery for one rotation period, as the ratio of the value of one angular sector to the angular velocity of the solar battery, set response threshold of not more than half of one angular sector, assign values equal to the angular position of the bisector of the angular sector within the boundaries of the cat The angular position of the projection of a unit direction vector onto the Sun is found, before starting the control, rotate the solar battery clockwise or counterclockwise and measure the current produced by it, stop the rotation of the solar battery after it begins to reduce the achieved current of the greatest magnitude, assign the value of the given angle to the calculated angle of the solar panel, the control time for the mismatch between the set and calculated angles in the order in which they memorize the moments of time the rotation ceases, the current reaches, activated by the solar battery, of the largest magnitude and the beginning of the next rotation, while in case of a decrease in the current generated by the solar battery, less than the minimum allowable, or when the highest generated current is reached at the moments of the end or beginning of the next rotation - change the value of the calculated angle after the end of the next rotation by the value Δα = ω _О · (t _ZAP2 -t _ZAP1 -0.5 · T _SB ),
where Δα is the correction to the calculated angle; ω _O is the angular orbital velocity of the spacecraft; t _ZAP1 - the stored value of the countdown time at the time of formation of the command to stop rotation; t _ZAP2 is the stored value of the countdown time at the moment the current produced by the solar battery reaches its maximum value; T _SB - the period of rotation of the solar battery, increase or decrease the calculated angle by the amount of correction during rotation of the solar battery during the countdown, respectively, in the direction of increasing or decreasing the angle.

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