CN102114917B - Processing method for enhancing control precision of magnetic torquer - Google Patents

Abstract

The invention provides a processing method for enhancing the control precision of a magnetic torquer. A satellite is magnetically controlled in a manner of pulse width modulation during normal running on a track. The processing method comprises the following specific steps of: (a) calculating an output torque Mi of the magnetic torquer, wherein i is equal to x, y or z; (b) calculating a working pulse width Wmi of the magnetic torquer, wherein i is equal to x, y or z; and (c) calculating a working pulse width Wmi' of the compensated magnetic torquer arranged on three shafts of the satellite, wherein i is equal to x, y or z. By the processing method, the magnetic torquer is compensated, so the actual output efficiency of the magnetic torquer can be improved, and the control precision of the system can be increased.

Description

A kind of processing method that improves the magnetic torquer control accuracy

Technical field

The present invention relates to aerospace automatic control's technology, be specifically related to a kind of processing method that improves the magnetic torquer control accuracy.

Background technology

The rail control subsystem of satellite generally is made up of sensor, actuating unit and controller.The space environment information calculations controlling quantity that controller is gathered through sensor sends to actuating unit with control signal and accomplishes the closed loop control to satellite attitude and track.

Magnetic torquer is one of main actuating unit of satellite, is made up of bar magnet that is wound with coil and driving circuit thereof, and is as shown in Figure 1.Controller provides control voltage, and the magnetic torquer line transfer becomes coil current Im, and sense of current is different, produces the magnetic moment of different directions.Magnetic moment and geomagnetic field mutual action produce moment, momentum wheel are unloaded and carry out attitude control, promptly

$\stackrel{\→}{T}=\stackrel{\→}{M}\×\stackrel{\→}{B}=\left[\begin{array}{ccc}0& -M_z& M_y\\ M_z& 0& -M_x\\ -M_y& M_x& 0\end{array}\right]\·\left[\begin{array}{c}{B}_x\\ B_y\\ B_z\end{array}\right]=\left[\begin{array}{c}-M_z{B}_y+M_y{B}_z\\ M_z{B}_x-M_x{B}_z\\ -M_y{B}_x+M_x{B}_y\end{array}\right]$ Formula (1)

In the following formula:

is moment; Unit is " newton meter second ", i.e. Nms;

Be the magnetic moment that magnetic torquer produces, unit is " an ampere per meter ²", i.e. Am ²

is the geomagnetic field; Unit is " tesal ", i.e. T;

B _i(i=x, y are that the geomagnetic field is at (the x of satellite body coordinates system z) _b, y _b, z _b) on component;

M _i(i=x, y are (x for magnetic torquer output magnetic moment in the satellite body coordinates z) _b, y _b, z _b) component.

Three magnetic torquers of the general employing of control system, mounting means is as shown in Figure 2, and the direction of magnetic torquer generation positive magnetic moment is parallel with three principal axis of inertia of satellite respectively.

Satellite adopts the mode of pulse duration modulation to carry out magnetic control when rail normally moves usually.The relation such as the formula (2) of magnetic moment and work pulsewidth

formula (2)

In the following formula:

M _MaxBe the maximum magnetic moment that magnetic torquer can be exported, the Am of unit ²

The attitude control cycle: the design-calculated satellite carries out the discrete steps of Attitude Calculation and control, unit: second;

W _Mi, i=x, y, z: be installed on the magnetic torquer work pulsewidth on three axles of satellite respectively, unit: second.

Control system is calculated the required pulsewidth of magnetic torquer after going out required control torque through the space environment information calculations, and provides the control voltage of respective widths, and the magnetic torquer circuit provides the respective coil electric current according to this voltage.The magnetic moment M of desirable magnetic torquer output is as shown in Figure 3 with the relation of control voltage.But because the existence of magnetic torquer coil inductance, the magnetic moment of real output is as shown in Figure 4.Actual work pulsewidth is because the rising delay time narrowed down with the fall delay time, and the moment and the controller that make output magnetic moment and earth magnetic field act on generation calculate needed moment has very large deviation, has influenced the control efficiency of satellite.

Summary of the invention

The object of the present invention is to provide a kind of processing method that improves the magnetic torquer control accuracy, output compensates to magnetic torquer for it, improves magnetic torquer real output efficient, thereby improves system's control accuracy.

Realize the technical scheme of the object of the invention: a kind of processing method that improves the magnetic torquer control accuracy, its satellite adopt the mode of pulse duration modulation to carry out magnetic control when rail normally moves; This method is carried out as follows:

(a) calculate magnetic torquer output magnetic moment M according to formula (1) _i(i=x, y, z)

$\stackrel{\→}{T}=\stackrel{\→}{M}\×\stackrel{\→}{B}=\left[\begin{array}{ccc}0& -M_z& M_y\\ M_z& 0& -M_x\\ -M_y& M_x& 0\end{array}\right]\·\left[\begin{array}{c}{B}_x\\ B_y\\ B_z\end{array}\right]=\left[\begin{array}{c}-M_z{B}_y+M_y{B}_z\\ M_z{B}_x-M_x{B}_z\\ -M_y{B}_x+M_x{B}_y\end{array}\right]$ Formula (1)

In the formula:

is moment; Unit is " newton meter second ", and

calculates through sensor image data and attitude dynamics;

Be the magnetic moment that magnetic torquer produces, unit is " an ampere per meter ²";

is the geomagnetic field, and unit is " tesal ";

B _i(i=x, y are that the geomagnetic field is at (the x of satellite body coordinates system z) _b, y _b, z _b) on component;

B _i(i=x, y z) are calculated by satellite orbit;

M _i(i=x, y are (x for magnetic torquer output magnetic moment in the satellite body coordinates z) _b, y _b, z _b) component;

(b) calculate magnetic torquer work pulsewidth W according to formula (2) then _Mi(i=x, y, z)

formula (2)

In the formula:

M _MaxBe the maximum magnetic moment that magnetic torquer can be exported, unit is " an ampere per meter ²";

The discrete steps that the attitude control cycle carries out Attitude Calculation and control for the design-calculated satellite, unit is " second ";

W _Mi, i=x, y, z is for being installed on the magnetic torquer work pulsewidth on three axles of satellite respectively, and unit is " second ";

(c) adopt formula (3) to calculate to obtain and be installed on the magnetic torquer work pulsewidth W on three axles of satellite respectively after the compensation _Mi', i=x, y, z

$W_{\mathrm{Mi}}^{\′}=W_{\mathrm{Mi}}+\mathrm{Sign}\left(W_{\mathrm{Mi}}\right)\·[(1/\mathrm{\τ}-k/2)\·(1-e^{-\mathrm{\τ}\left|W_{\mathrm{Mi}}\right|})],i=x,y,z$ Formula (3)

In the formula:

τ: rise-time constant, unit is " second ";

K: decline maximum delay constant, unit are " second ".

Aforesaid a kind of processing method that improves the magnetic torquer control accuracy, its described constant τ and k are obtained through match after the actual measurement by magnetic torquer coil and the decision of driver circuit characteristic; Promptly do not having under the magnetic torquer compensation situation, given certain work pulsewidth is with oscilloscope measurement build up time and decline maximum delay time.

Effect of the present invention is: a kind of processing method that improves the magnetic torquer control accuracy of the present invention; It obtains the magnetic torquer work pulsewidth on three axles of satellite after the compensation; Output compensates to magnetic torquer; Can improve magnetic torquer real output efficient, thereby improve system's control accuracy.

Description of drawings

Fig. 1 forms and schematic diagram for magnetic torquer;

Fig. 2 is magnetic torquer mounting means figure;

Fig. 3 is perfect condition lower magnetic force square device output magnetic moment figure;

Fig. 4 is actual magnetic moment output map;

Fig. 5 is for adding preceding magnetic torquer pulsewidth of compensation and control voltage relationship figure;

Fig. 6 is magnetic torquer output pulse width and make-up time graph of a relation.

The specific embodiment

A kind of processing method that improves the magnetic torquer control accuracy of the present invention, its satellite adopt the mode of pulse duration modulation to carry out magnetic control when rail normally moves; Specifically carry out as follows:

(a) calculate magnetic torquer output magnetic moment M according to formula (1) _i(i=x, y, z)

$\stackrel{\→}{T}=\stackrel{\→}{M}\×\stackrel{\→}{B}=\left[\begin{array}{ccc}0& -M_z& M_y\\ M_z& 0& -M_x\\ -M_y& M_x& 0\end{array}\right]\·\left[\begin{array}{c}{B}_x\\ B_y\\ B_z\end{array}\right]=\left[\begin{array}{c}-M_z{B}_y+M_y{B}_z\\ M_z{B}_x-M_x{B}_z\\ -M_y{B}_x+M_x{B}_y\end{array}\right]$ Formula (1)

In the formula:

is moment; Unit is " newton meter second ", and

calculates through sensor image data and attitude dynamics;

Be the magnetic moment that magnetic torquer produces, unit is " an ampere per meter ²";

is the geomagnetic field, and unit is " tesal ";

B _i(i=x, y are that the geomagnetic field is at (the x of satellite body coordinates system z) _b, y _b, z _b) on component;

B _i(i=x, y z) are calculated by satellite orbit;

M _i(i=x, y are (x for magnetic torquer output magnetic moment in the satellite body coordinates z) _b, y _b, z _b) component;

(b) calculate magnetic torquer work pulsewidth W according to formula (2) _Mi(i=x, y, z)

formula (2)

In the formula:

M _MaxBe the maximum magnetic moment that magnetic torquer can be exported, unit is " an ampere per meter ²";

The discrete steps that the attitude control cycle carries out Attitude Calculation and control for the design-calculated satellite, unit is " second ";

W _Mi, i=x, y, z is for being installed on the magnetic torquer work pulsewidth on three axles of satellite respectively, and unit is " second ";

(c) adopt magnetic that formula (3) compensates part apart from calculating, obtain to be installed on the magnetic torquer work pulsewidth W on three axles of satellite respectively after the compensation _Mi', i=x, y, z

$W_{\mathrm{Mi}}^{\′}=W_{\mathrm{Mi}}+\mathrm{Sign}\left(W_{\mathrm{Mi}}\right)\·[(1/\mathrm{\τ}-k/2)\·(1-e^{-\mathrm{\τ}\left|W_{\mathrm{Mi}}\right|})],i=x,y,z$ Formula (3)

In the formula:

τ: rise-time constant, unit is " second ";

K: decline maximum delay constant, unit are " second ";

Above constant τ and k are obtained through match after the actual measurement by magnetic torquer coil and the decision of driver circuit characteristic; Promptly do not having under the magnetic torquer compensation situation, given certain work pulsewidth is with oscilloscope measurement build up time and decline maximum delay time.

Below in conjunction with accompanying drawing and specific embodiment a kind of processing method that improves the magnetic torquer control accuracy of the present invention is further described.This instance is under technical scheme of the present invention, to carry out, but scope of the present invention is not limited to this instance.

Certain satellite attitude control cycle is 1s, adopts 50Am ²Magnetic torquer (is M _Max=50Am ²), carry out magnetic torquer pulsewidth compensation before, the work pulsewidth that calculates by existing method and relation curve such as Fig. 5 of control voltage, wherein transverse axis is the magnetic torquer work pulsewidth W that calculates _Mi, the longitudinal axis can be found out by Fig. 5 that for control voltage V build up time was about 0.35 second when pulsewidth was 0.4 second.Can know by formula (2), extrapolate the required magnetic moment of control according to required control torque and should be:

$M=50\·\frac{0.4}{1}=20A{m}^2$

And in fact maximum magnetic moment was not all exported in magnetic moment output in 0.4 second, was merely 76% of required magnetic moment through The Fitting Calculation real output magnetic moment.

As τ=10.25ms, k=40ms, the pulsewidth before and after the compensation that obtains is as shown in Figure 6.Pulsewidth before the compensation that calculates for existing method of transverse axis wherein, the longitudinal axis are the pulse width after compensation that formula (3) obtains is calculated.Can know 0.4 second pulsewidth before compensation by figure, be about 0.477 second after the compensation.

After carrying out the compensation of magnetic torquer pulsewidth according to the method described above, the required magnetic moment of real output magnetic moment and Theoretical Calculation is suitable.

Claims (1)

1. processing method that improves the magnetic torquer control accuracy, its satellite adopts the mode of pulse duration modulation to carry out magnetic control when rail normally moves; This method is carried out as follows:

(a) calculate magnetic torquer output magnetic moment M according to formula (1) _i(i=x, y, z)

$\stackrel{\→}{T}=\stackrel{\→}{M}\×\stackrel{\→}{B}=\left[\begin{array}{ccc}0& -M_z& M_y\\ M_z& 0& -M_x\\ -M_y& M_x& 0\end{array}\right]\·\left[\begin{array}{c}{B}_x\\ B_y\\ B_z\end{array}\right]=\left[\begin{array}{c}-M_z{B}_y+M_y{B}_z\\ M_z{B}_x-M_x{B}_z\\ -M_y{B}_x+M_x{B}_y\end{array}\right]$ Formula (1)

In the formula:

is moment; Unit is " newton meter second ", and calculates through sensor image data and attitude dynamics;

Be the magnetic moment that magnetic torquer produces, unit is " an ampere per meter ²";

is the geomagnetic field, and unit is " tesal ";

B _i(i=x, y are that the geomagnetic field is at (the x of satellite body coordinates system z) _b, y _b, z _b) on component; B _i(i=x, y z) are calculated by satellite orbit;

M _i(i=x, y are (x for magnetic torquer output magnetic moment in the satellite body coordinates z) _b, y _b, z _b) component;

(b) calculate magnetic torquer work pulsewidth W according to formula (2) then _Mi(i=x, y, z)

formula (2)

In the formula:

M _MaxBe the maximum magnetic moment that magnetic torquer can be exported, unit is " an ampere per meter ²";

The discrete steps that the attitude control cycle carries out Attitude Calculation and control for the design-calculated satellite, unit is " second ";

W _Mi, i=x, y, z is for being installed on the magnetic torquer work pulsewidth on three axles of satellite respectively, and unit is " second ";

It is characterized in that: adopt formula (3) to calculate to obtain to be installed on the magnetic torquer work pulsewidth W on three axles of satellite respectively after the compensation _Mi', i=x, y, z

$W_{\mathrm{Mi}}^{\′}=W_{\mathrm{Mi}}+\mathrm{Sign}\left(W_{\mathrm{Mi}}\right)\·[(1/\mathrm{\τ}-k/2)\·(1-e^{-\mathrm{\τ}\left|W_{\mathrm{Mi}}\right|})],i=x,y,z$ Formula (3)

In the formula:

τ: rise-time constant, unit is " second ";

K: decline maximum delay constant, unit are " second ";

Described constant τ and k are obtained through match after the actual measurement by magnetic torquer coil and the decision of driver circuit characteristic; Promptly do not having under the magnetic torquer compensation situation, given certain work pulsewidth is with oscilloscope measurement build up time and decline maximum delay time.

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