RU2509694C1 - Method of control over spacecraft solar battery orientation with limitation of solar battery turn angle - Google Patents

Abstract

FIELD: transport.

SUBSTANCE: invention relates to spacecraft electric power supply with the help of solar batteries. Proposed method comprises definition of preset angle of solar battery orientation to the Sun by measured angular position of normal to battery working surface and computation of design angle relative thereto. Solar battery is spinned in direction of decrease in mismatch between preset and design angles. Solar battery acceleration angle (α_AC) and deceleration angle (α_DEC) are defined. Design angle is corrected when angle transducer readings vary by discrete sector of solar battery turn. Threshold of operation and drop-away (α_T) and (α_D) are set to terminate battery spinning if mismatch between preset angle and current angle increases but not over α_T. Solar battery angular velocity is set or the order and larger than maximum angular velocity of spacecraft revolution around the Earth while discrete sector magnitude is set to smaller than α_T. Solar battery working angle (α_W) is set provided that α_T < α_W < (α_"ГОР" - 2·(α_AC + α_DEC)). Angular position of closest beam of angle α_W is assigned to preset angle if direction to the Sun in projection to the plane of spinning of said normal is located outside of α_W. Is angular position of said normal is outside α_W to vary in direction of increase of angle relative to nearest beam of angle α_W, failure warning is generated to terminate control over solar battery.

EFFECT: ruled out jamming and breakage of solar battery panels or spacecraft onboard hardware at turns from 90° to 180°.

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Description

The method for controlling the orientation of the solar battery of a spacecraft with a limitation of the angle of rotation of the solar battery relates to power supply systems for spacecraft (SC) and can be used to control satellites with circular or elliptical orbits. Electric power supply to the spacecraft onboard equipment, including the charge of its storage batteries, is carried out using solar panels (SB). The magnitude of the current generated by the SB depends on the orientation of the plane of its working surface relative to the Sun.

SB orientation is controlled by on-board automatic control systems that control SB rotation devices consisting of electronic units and electromechanical drives with panels and SB position sensors mounted on the output shaft.

The on-board automatic control systems include on-board digital computers, which implement spacecraft motion control algorithms, as well as onboard equipment control, including SB orientation control algorithms.

The on-board automatic control system, using information from appropriate sensors (astro sensors, solar position sensors, etc.), determines the position of the spacecraft in space and the direction to the sun relative to the coordinate axes associated with the spacecraft using motion control tools (orbital maneuvering engines, gas engines, and etc.) controls the position of the spacecraft in space, and with the help of rotation devices the SB controls the orientation of the SB panels.

Thus, in accordance with the algorithms laid down, the on-board automatic control system determines the current angular positions of the direction vector to the Sun and the normal to the working surface of the SB relative to the coordinate axes associated with the spacecraft. Upon reaching a mismatch between the indicated angular positions, the on-board automatic control system generates commands for rotating the SB clockwise or counterclockwise to reduce it, and the absence of a mismatch generates commands for stopping the rotation of the SB.

Depending on the purpose of the spacecraft, the features of its design, the required characteristics of power supply, the operating life and other factors, one or more SBs can be installed onboard the spacecraft. The rotation devices used in modern spacecraft allow rotation of the SB panels in a 360 ° circle. At the same time, onboard equipment installed on the spacecraft, for example for scientific research, in some angular positions may come into contact with the SB panel, as a result of which jamming or breakdown of the SB panels or onboard equipment may occur. With this limitation, the permissible angle of rotation of the SB is less than 180 °. At the same time, to perform a number of tasks, for example, to study certain areas and objects of outer space, the position of the spacecraft must change in a limited range of angles, or be fixed relative to the object under study. In this regard, the control process takes into account the parameters of the specified orbit, the required orientation of the spacecraft during long-term space exploration, as well as the location of the onboard equipment that limits the angle of rotation of the SB. At the same time, these parameters are set so that the SB panel provides the maximum possible current, and the direction to the Sun for the SB during these studies would change within or close to the boundaries of the angle of limitation. Thus, the task is to effectively control the orientation of the SB in order to ensure the maximum possible current while limiting the angle of rotation of the SB less than 180 °.

The closest technical solution adopted for the prototype is a method for controlling the position of the SB, the essence of which is that the angular velocity of the SB is determined, then the calculated angle relative to the measured angular position of the SB is calculated from the SB crossing the boundaries between the discrete sectors of the angle sensor. This angle is calculated as the product of the angular velocity of the SB by the time of its rotation. Rotate the SB in the direction of reducing the mismatch between the specified and its calculated angles. At the appropriate angles of the deviation of the normal to the working surface of the SB determine the takeoff and braking angles of the SB. Correct the calculated angle by the measured angular position of the indicated normal at the moments of change in the readings of the angle sensor by the value of one discrete sector. On the run-up and braking angles, as well as the minimum allowable and maximum possible currents generated by the SB, set the threshold. If the specified threshold is exceeded, a mismatch is formed between the specified and calculated angles of the SB. The release threshold is set, less than which the mismatch between the set and calculated angles of the SB stops. The rotation of the SB is stopped if the mismatch between the specified and calculated angles begins to increase, but does not exceed the threshold [1].

The technical task of the invention is to expand the functionality of the method of controlling the orientation of the SB in order to prevent jamming or breakage of the SB panel or on-board equipment of the spacecraft and ensuring the maximum possible current under conditions of restrictions on the rotation angles of the SB.

The specified technical result is achieved by the fact that in the known method of controlling the position 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 angular position of the normal to the working surface of the solar battery relative to the coordinate axes associated with the spacecraft in the plane rotation of the solar battery, accurate to the discrete sector of the corresponding angle sensor, determine the angular velocity of rotation of the solar battery by the time the solar battery crosses the boundary between the discrete sectors of the angle sensor, calculate the calculated angle relative to the measured angular position of the solar battery as the product of the angular velocity of the solar battery by the time of its rotation, rotate the solar battery in the direction of reducing the mismatch between the set and calculated angles, determine the angle of acceleration of the sun hydrochloric battery and the braking angle is corrected angle calculated from the measured angular position of said moments of change in the normal angle sensor values by the amount of discrete sectors, define the threshold above which formed a mismatch between the target and the calculated angles as:

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

,

where α _CP is the response threshold;

α _RAG - the angle of acceleration of the solar battery;

α _TORM - angle of braking of the solar battery;

I _MIN - minimum allowable current generated by the solar battery;

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

set the release threshold, less than which the mismatch between the set and calculated angles of the solar battery ceases, as:

α _OTP ≈α _TORM ,

where α _OPT is the release threshold,

stop the rotation of the solar battery if the mismatch between the given and current angles begins to increase, but does not exceed the threshold, additionally set the angular velocity of rotation of the solar battery by an order of magnitude and higher than the maximum angular velocity of rotation of the spacecraft around the Earth, set the angular value of the discrete sector of the angle sensor less than the threshold operation, and the angle of rotation limitation of the solar battery in the range:

90 ° ≤α _OGR <180 °,

where α _OGR - angle of rotation limitation of the solar battery, set the working angle of the solar battery, the bisector of which coincides with the bisector of the angle of limitation, as:

α _SR <α _RAB <(α _ORG -2 · ((α _RAZG + α _TORM )),

where α _RAB is the working angle of the solar battery,

assign to the given angle the value of the angular position of the beam of the working angle closest to it, if the position of the projection of the unit direction vector on the Sun above is outside the working angle, a failure signal is generated and control of the solar battery is stopped, if the angular position of the normal to the working surface of the solar battery is outside the working angle and it changes in the direction of increasing the angle relative to the nearest ray of the working angle.

Figure 1 shows the position of the spacecraft relative to the Sun and the Earth, figure 2 - angle sensor, made in the form of a circle of rotation of the SB, figure 3 - possible normal to the working surface of the SB in the circle of rotation of the SB.

The method of controlling the orientation of the solar battery of a spacecraft with a limitation of the angle of rotation of the solar battery is implemented as follows.

The SB rotation device has an electromechanical drive with an angular velocity of rotation of the output shaft an order of magnitude and more than the maximum angular velocity of rotation of the spacecraft around the Earth at the perigee of the orbit, that is:

w _SB> 10 · ω _O

where ω _SB - steady-state angular velocity of SB;

ω _О - angular velocity of rotation of the spacecraft around the Earth.

According to the passport data, as well as the results of experiments on the stands, the acceleration angle α _{RAG of the} output shaft of the electromechanical drive with the SB fixed to it is determined as the angular deviation of the normal to the SB working surface relative to the coordinate axes associated with the SC from the moment of the appearance of a mismatch between the given and current angles until SB steady-state angular velocity SB. In addition, the braking angle α _{TORM of the} output shaft of the electromechanical drive with the SB attached to it is determined as the angular deviation of the normal to the SB working surface from the moment the mismatch between the given and current SB angles ceases in the presence of a steady angular velocity until the SB rotation stops completely.

As you know, the current generated by the SB panel is determined by the equation:

$$I=I_{MAX}\cdot COS|\; |\; |{\mathrm{<figure-callout\; id="3"\; label="\alpha "\; filenames="00000010.png"\; state="\{\{state\}\}">\alpha </figure-callout>}}_{3\mathrm{BUT}D}-{\alpha }_{TE\mathrm{TO}}|\; |\; |,(\mathrm{one})$$

where I is the current generated by the SB;

I _MAX is the maximum possible current generated by the SB, when the projection of the unit direction vector onto the Sun coincides with the normal to the working surface of the SB in the normal rotation plane;

α _TEK - current angle of the SB;

α _REF - set angle SB;

| α _REQUEST -α _TEK | - the module of the difference between the given and current angles of the SB.

Given equation (1), the response threshold is set as the angle at which a mismatch signal is generated between the given and current angular position of the SB, as:

$$\left({\alpha }_{R\mathrm{BUT}3B}+{\alpha }_{T\mathrm{ABOUT}RM}\right)<{\alpha }_{CP}<\arccos \frac{I_{MIN}}{I_{MAX}},(2)$$

where α _CP is the SB threshold;

α _Razg - SB acceleration angle;

α _TORM - angle of braking SB;

I _MIN - set minimum permissible current generated by the SB to power the spacecraft onboard equipment;

I _MAX is the maximum possible current generated by the SB when the normal to the working surface of the SB coincides with the projection of a unit direction vector onto the Sun on the plane of rotation of the SB,

then set the release threshold at which the formation of the error signal between the given and the current angle of the SB stops, as:

$${\alpha }_{\mathrm{ABOUT}TP}\approx {\alpha }_{T\mathrm{ABOUT}RM},(3)$$

where α _OTP is the release threshold.

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

$$\sigma =\frac{360}{n}<{\alpha }_{CP},(\mathrm{four})$$

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

n is the number of discrete sectors in the circle of rotation of the SB.

According to the results of experiments on the stands, the angle of restriction formed by two normal positions to the working surface of the SB is determined, in which the structural elements of the spacecraft are in contact with the structural elements of the SB, and these contacts are absent inside the restriction angle, while the restriction angle is in the range:

$${90}^{\circ }<{\alpha }_{\mathrm{ABOUT}GR}<{108}^{\circ },(5)$$

where α _OGR - angle of limitation SB.

Set the working angle of the SB, the bisector of which coincides with the bisector of the angle of restriction, as:

$${\alpha }_{R\mathrm{BUT}B}<{\alpha }_{\mathrm{ABOUT}GR}-2\cdot \left({\alpha }_{R\mathrm{BUT}3G}+{\alpha }_{T\mathrm{ABOUT}RM}\right),(6)$$

where α _RAB - working angle SB.

During the spacecraft’s orbit flight using sensors (solar position sensors, astro sensors), and also by calculating the coordinate system related to the spacecraft, 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 is determined. In addition, the current SB angle is determined as the position of the normal indicated above with respect to the coordinate axes associated with the spacecraft.

If the projection of a unit direction vector onto the Sun is within the boundaries of the working angle, then if there is a mismatch between the set and the current angle of the SB more than the angle of operation, a command is formed to rotate the SB along the shortest path in the direction of decreasing the angle of mismatch. In this case, the current angle is calculated as the product of the angular velocity and the time of rotation of the SB, and at the moments of the normal crossing the SB working surface of the boundary between the discrete sectors of the angle sensor, the actual value of the crossed border is assigned to the current angle. Thus, the current angle of the SB is determined as:

$${\alpha }_{TE\mathrm{TO}}{\alpha }_{Fi}{\omega }_{\mathrm{FROM}B}{t}_i,(7)$$

where α _TEK is the current angle of the SB;

α _Фi is the actual angle of the SB at the moment of crossing the i-th boundary between the discrete sectors of the angle sensor;

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

t _i - the time of rotation of the SB from the moment of crossing the i-th border, while 0≤i≤ (n-1).

Form a command to stop the rotation of the SB, if the mismatch between the given and current angles reaches the angle of release.

If the position of the projection of the unit direction vector onto the Sun is outside the working angle, a value equal to the angular position of the beam of the working angle closest to it is assigned to the given angle. The angular position of the normal may differ from the angular position of the nearest ray of the working angle by no more than the threshold, but during normal operation it is always within this angle.

If the angular position of the normal to the working surface of the SB is outside the working angle and at the same time continues to change in the direction of increase from the beam of the working angle closest to it, a failure signal is generated and the control of the SB is stopped.

Figure 1 shows the position of the spacecraft relative to the Sun and the Earth,

Where

1 - Earth;

2 - spacecraft orbit;

3 - spacecraft body;

4 - SB panel;

5 - scientific equipment of the spacecraft;

6 - angle sensor SB;

7 - the direction of radiation from the Sun;

8 - shadow area of the orbit;

9 - object of observation;

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 - axis associated with the spacecraft coordinate system;

X _SB , Y _SB , Z _SB - the axis of the coordinate system associated with the SB;

N _SBA , N _SBV - normal to the working surface of the SB, in which the SB panel is in contact with the spacecraft equipment;

ω _O is the direction of the angular orbital velocity of the spacecraft relative to the Earth;

ω _SB - the direction of the angular velocity of SB relative to the Z axis;

α _OGR - angle of rotation restriction of the SB panel;

Δ _α is the mismatch angle of the normal to the working surface of the SB and the given direction of orientation of the SB.

Around the Earth 1 in orbit 2 with an angular velocity ω _O rotates the spacecraft. The X, Y, Z axis of the coordinate system associated with the SC is rigidly connected to the body 3 of the SC. On the spacecraft body 3, a SB 4 panel is installed, as well as scientific equipment 5 (for example, a radio telescope). Axes X _SB , Y _SB , Z _SB form a coordinate system associated with the SB. Sa _Sa rotates around the Z axis, and Z axis directions _Sa and Z coincide, and the plane formed by the axes X and Y _{Sa Sa} parallel to the plane defined by axes X and Y. The direction normal to the working surface Sa _Sa N coincides with the direction of the axis X _Sa . The angular position of the indicated normal N _SB is determined using the angle sensor 6 SB mounted on the body 3 of the SC, and the specified angle sensor 6 generates a zero value when the directions of the X axes _SB and X coincide. In accordance with the direction of the radiation of the Sun 7, the projection direction of the unit direction vector is determined on the Sun N on a plane formed by the axes X _SB and Y _SB . During the flight of the spacecraft in orbit 2, it periodically falls into the shadow of the Earth 8.

If the normal position of the N _SB coincides with the positions of the N _SBA and N _SBV beams, the 4 SB panel is in contact with the spacecraft equipment. Thus, the rotation of the SB panel around the Z axis of the _{SB is} limited by the angle α _OGR formed by the rays N _SBA and N _SBV . During the flight, the SB panel 4 is deployed in such a way as to ensure a minimum mismatch angle Δα between the projection direction of a unit direction vector on the Sun N onto the plane of rotation of the normal to the SB working surface formed by the X _SB and Y _SB axes and the indicated N _SB normal, resulting in the formation of the maximum possible current is ensured.

In the working position, the spacecraft is deployed so that the scientific equipment 5 installed on its board provides orientation to the object of observation 9.

At the working section of the rotation of the SB panel, that is, if the normal N _SB is within the boundaries of the limiting angle α _OGR and if the mismatch between the position of the indicated normal N _SB and the projection N becomes greater than the response threshold, the SB panel is deployed with the angular velocity ω _SB until the normal N position coincides _SB with the projection position N. If the projection N is outside the angle of limitation, the normal N _SB occupies positions inside the angle α _OGR close to the positions N _SBA and N _SBV .

Ha figure 2 presents the angle sensor, made in the form of a circle of rotation of the SB, where:

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

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

12 - design elements of the spacecraft, limiting the rotation of the SB;

13, 14 — positions of the SB panel;

N _SBA - the position of the normal to the working surface of the SB, corresponding to position 13 of the panel;

N _SBV - the position of the normal to the working surface of the SB, corresponding to position 14 of the panel;

α _OGR - angle of rotation limitation SB.

In the rotation circle 10, the angle sensor measures the position of the normal to the working surface of the SB relative to the coordinate axes associated with the spacecraft. The drawing shows the fixed values of the angle sensor 0 °, 90 °, 180 °, 270 °. The center of the circle 11 coincides with the axis Z of the _SB , perpendicular to the plane of rotation of the normal. Structural elements of 12 KA in positions 13 and 14 of the SB panels are in contact with it and thus physically limit the rotation of the SB panel, while the rays of the angle of restriction α _OGR correspond to the normal positions of N _SBA and N _SBV .

Figure 3 presents the possible position of the normal to the working surface of the SB in the circle of rotation of the SB, where:

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

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

N ₁ , N ₂ , N ₃ , N _A , N _B , N _RAB , N _ZAP - the position of the projections of the unit direction vector on the Sun, on the plane of rotation of the normal to the working surface of the SB;

N _SB1 , N _SB2 , N _SB2 , N _SB4 , N _OGRA , N _OGRA , N _OGRV - the position of the normal to the working surface of the SB;

α _OGR - angle of rotation limitation SB;

α _ZAP - angle of prohibition of rotation of the SB;

α _RAB - working angle SB;

α _A , α _B - buffer angles;

Δα _A , Δα _B - mismatch angles between the given and the current angles of the SB.

In the rotation circle 15 normal to the SB working surface with center 16, the angle of restriction α _{OGR of} the SB rotation angle is formed by the N _OGRA and N _OGRV beams corresponding to the normal positions to the SB working surface, in which the spacecraft onboard equipment is in contact with the SB panel.

The value of the angle of the prohibition of rotation α _ZAP SB is determined as:

α _ZAP = 360-α _OGR .

The working angle α _RAB SB is formed by the rays N _A and N _B , the angular positions of which correspond to the values of the given angle, if the projection of the unit direction vector onto the Sun goes beyond its limits.

The buffer angles α _A and α _B , each of which is more than the sum of the angles of acceleration and deceleration, are formed by the rays N _A , N _OGRA and N _B and N _OGRV, respectively, while:

. $${\alpha }_{\mathrm{BUT}}={\alpha }_{\mathrm{AT}}=\frac{\mathrm{one}}{2}\cdot \left({360}^{\circ }-{\mathrm{<figure-callout\; id="3"\; label="\alpha "\; filenames="00000010.png"\; state="\{\{state\}\}">\alpha </figure-callout>}}_{3\mathrm{BUT}P}-{\alpha }_{R\mathrm{BUT}B}\right)$$

.

The control of the orientation of the SB depends on the position of the projection of a unit vector of a given direction on the Sun in this circle, as well as the position of the normal to the working surface of the SB.

If the specified projection occupies a position within the boundaries of the working angle N ₁ , then at the time of the end of the rotation of the SB, the normal to the working surface of the SB takes position N _SB1 , which coincides with the position N ₁ .

If the projection is outside the working angle, but within the boundaries formed by the rays N _B , N _ZAP , then the normal position N _СБ3 is within the working angle and can differ from the position of the beam N _A by no more than the threshold.

If the projection is outside the working angle, but within the boundaries formed by the rays N _B , N _ZAP , then the normal position N _СБ3 is within the working angle and may differ from the position of the beam N _B by an amount not exceeding the threshold.

If the position of the normal goes beyond the working angle α _RAB , for example, corresponds to the provisions of N _SB4 or N _SB5 and at the same time a change in the position of the normal in the direction to the nearest beam of the angle of restriction, respectively, N _OGRA or N _OGRV , a failure signal is generated and the control of the SB stops.

The proposed method eliminates jamming or breakdown of the SB panel or onboard equipment of the spacecraft in the conditions of limiting the angle of rotation of the SB and ensure its orientation in such a way as to obtain the maximum possible current.

Information sources

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

Claims (1)

The method of controlling the orientation of the solar battery of a spacecraft with a limitation of the angle of rotation 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 the coordinate axes associated with the spacecraft, measure the angular the position of the normal to the working surface of the solar battery relative to the coordinate axes associated with the spacecraft in the plane of rotation of the solar th battery accurate to the discrete sector of the corresponding angle sensor, determine the angular velocity of rotation of the solar battery by the time the solar battery crosses the boundary between the discrete sectors of the angle sensor, calculate the calculated angle relative to the measured angular position of the solar battery as the product of the angular velocity of the solar battery by the time of its rotation, rotate the solar battery in the direction of reducing the mismatch between the set and calculated angles, determine the angle of acceleration of the solar battery and inhibition, corrected angle calculated from the measured angular position of said moments of change in the normal angle sensor values by the amount of discrete sectors, define the threshold above which formed a mismatch between the target and the calculated angles as:
$$\left({\alpha }_{R\mathrm{BUT}3G}+{\alpha }_{T\mathrm{ABOUT}RM}\right)<{\alpha }_{CP}<\arccos \frac{I_{MIN}}{I_{MAX}}$$

,
where α _СР - response threshold;
α _RAG - the angle of acceleration of the solar battery;
α _TORM - angle of braking of the solar battery;
I _MIN - minimum allowable current generated by the solar battery;
I _MAX - the maximum possible current generated by the solar battery, set the release threshold, less than which the mismatch between the set and calculated angles of the solar battery stops, as:
α _OTP ≈ α _TORM ,
where α _OTP is the release threshold,
the rotation of the solar battery is stopped if the mismatch between the given and current angles begins to increase, but does not exceed the response threshold, characterized in that the angular velocity of rotation of the solar battery is set by an order of magnitude and higher than the maximum angular velocity of the spacecraft around the Earth, the angular value of the sensor’s discrete sector is set angle less than the threshold, and the angle of rotation limitation of the solar battery in the range:
90 ° ≤ α _OGR <180 °,
where α _OGR - angle of rotation limit of the solar battery,
set the working angle of the solar battery, the bisector of which coincides with the bisector of the angle of limitation, as:
α _SR <α _RAB <(α _GOR -2 · (α _RAG + α _TORM )),
where α _RAB is the working angle of the solar battery,
assign to the given angle the value of the angular position of the beam of the working angle closest to it, if the position of the projection of the unit direction vector on the Sun above is outside the working angle, a failure signal is generated and control of the solar battery is stopped, if the angular position of the normal to the working surface of the solar battery is outside the working angle and it changes in the direction of increasing the angle relative to the nearest ray of the working angle.

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