Space vehicle correction engine test method

FIELD: instrumentation.

SUBSTANCE: invention relates to control of movement of space vehicle (SV). According to the proposed method, thrusts of correction engines (CE) (control accelerations) are determined as per total changes in a period of SV revolution from correction to correction. The latter are performed with one and the same CE and a thrust level of those CE is estimated. For reliable understanding of thrusts of a pair of mutually opposite located CE, series control activations of the same pair are performed from time to time with equal pulses. Discrepancy as to total pulse of thrust is entered in equal parts with an opposite sign to the implemented pulses. As a result, reliable thrust levels of CE in operation are obtained.

EFFECT: reduction of costs and improvement of CE thrust determination accuracy as per the data of trajectory measurements, as well as improvement of SV orbit correction accuracy.

The present invention relates to the field of space technology and can be used to adjust the parameters of motion of the SPACECRAFT (SC).

1. The company from the prior art known method of correcting elements of the orbit of geostationary spacecraft, based on the determination of rods of engines according to the trajectory of ground-based measurements. The essence of this method consists in the following.

1. Spend trajectory measurements.

Trajectory measurements were carried out using funds from a ground control center (GCC), mutually spaced around the territory of the Russian Federation for long distances. Trajectory measurements can be performed as a radio and optical means, while the measured parameters may be inclined range (measuring point - KA), the rate of change of slant range and Equatorial coordinates right ascension and declination of the SPACECRAFT.

Measuring information transmitted from the measuring points in GCC ballistic centers, processing this information and determine the actual orbital elements of the SPACECRAFT.

Trajectory measurements represent the standard measurement cycle current navigation parameters (ITP), the number of sessions of measurements and the number of intervals between sessions of the pillar is t for the daily interval and having two points of ground-based measurements from 4 to 6.

2. Make a test exposure.

To do this, at the scheduled time, switch on the engine correction (DC) of the desired thrust direction and work out the pulse, providing the change of the adjustable parameter, such as the orbital period.

The duration of the test exposure is chosen such that it is, on the one hand, led to small changes of the orbital elements, and on the other hand, that these changes were sufficient for reliable determination of the magnitude of the thrust DK. For example, when the thrust of the engine 0,08 N (8 HS) the duration of the test exposure for a SPACECRAFT with a mass of 2000 kg in geostationary orbit is about 2 h, and the corresponding tranversely pulse ~575 NS, which corresponds to the change of the orbital period of the SPACECRAFT, depending on the angles DK, (2,5-24,5) C. When the error of the determination of this parameter is 0.1 s, the error in determining the thrust is less than 5% is a good result. The random component of error implementing thrust is 3%, then the true thrust will be determined with an error of F(1±0,03)·0,05=0,05 F, i.e., the same 5%.

3. Spend trajectory measurements.

Trajectory is measured similarly to p. 1. Pull the DC is determined by the actual value of the change in the adjustable parameter is the orbital period.

4. Determine the actual value of the change in corrector is imago parameter and determine cravings DC.

Pull the DC is determined by the actual value of the change in the adjustable parameter is the orbital period.

As necessary, PP.1-4 is repeated for each of the DC motor correction.

After a certain period of time, as the lifespan of the systematic component of the thrust variable, repeat the full cycle (PP.1-4) testing of all DC.

5. Take corrective action.

For this purpose the estimated time switch on DK desired thrust direction. Duration of JC set based on the value of thrust produced when the test enable. Inclusion of DK is changing the adjustable parameter, such as the orbital period of the SPACECRAFT. However, due to the fact that the engine thrust correction may change the required values of the adjustable parameter, as a rule, cannot be implemented in a single application of corrective action.

6. Spend trajectory measurements and precise traction DK. The operation was performed similarly to PP.3, 4.

7. Take corrective action.

Switch on the DC required thrust direction at the time determined on the basis of traction DK, obtained by the test and the previous inclusions.

If necessary, PP.6, 7 is repeated to achieve the required accuracy of the spine of the adjustable parameter.

The disadvantage of method 1 is that:

1 - full cycle of testing all of the DC, including redundant circuits on the SPACECRAFT reaches up to 16 arbitrary numbers, collectively stretches, at least a month and includes in addition to the standard schedule 16 full-time cycles ITP;

2 - the required value of the adjustable parameter is achieved, as a rule, two corrections within 2 days, this requires planning two regular cycles ITP.

This is a very expensive way, which, although it is extremely reliable as possible we have to go. It was used when the correction parameters of the orbit was performed no more than once per month. Currently, when the correction parameters of the orbit can be conducted with a frequency of once a day or even less, it can be argued that:

1 - in the absence of Autonomous on-Board navigation or daily ICNP means NKU way practically not applicable;

2 - in the presence of Autonomous on-Board navigation or daily ICNP means NKU has a more efficient way of definition (specification) of thrust DK set forth below.

2. In the practice of the JSC "ISS" is more often used another way to Refine rods DK. It uses a heuristic approach: there are initial conditions (WELL) the motion for the previous ITP, there are the current settings (so what) movement, have spent a plan of correction that includes up to two arbitrary numbers DK, solved the problem of forecasting the movement of the parish in current traffic conditions) without much error. In the method-analogue 2 performs the following sequence of operations (irrelevant details are omitted).

1. Worked out a plan of correction.

2. Spend trajectory measurements.

With an auxiliary (side) navigation trajectory measurements are conducted in a continuous mode.

3. Implementing program to determine the parameters of motion of the center of mass of the SPACECRAFT.

4. Precise control of acceleration change of the orbital parameters. Refinement is not possible to determine the control acceleration more precisely the range of values of the accelerations specified by the manufacturer. It guarantees the tracking of abnormal JC, and, in the case of prolonged and possibly permanent situation, when (while) the refusal DK not recorded on Board the SPACECRAFT, still expect a plan of correction.

5. Perform the calculation program (compilation) plan corrections KA at step interval.

Step interval is 1 day in the presence of Autonomous on-Board navigation or daily ITP (daily trajectory measurements - HILDREN) days or more - in the absence of THESE.

6. Depending on the organization ballistic flight support KA on the ORT CA are written plan of correction and control of acceleration or only specified control acceleration.

Next paragraphs.1-6 are repeated during the whole time the AC for its intended purpose.

The accuracy of this method exceeds the tolerance specified by the manufacturer of the propulsion system. The fact that the definition of thrust two DC in the range of plan (1 day) and even the definition of thrust of one of the DC, with a single-turn on a small (usually) the duration when the QUESTION is not solved satisfactorily task. The problem of determining the thrust of more than two DC solution is not. If there HILDREN importantly, when calculating the correction parameters (one-two on the engine(s) on the daily interval) always assume that a change of control of the adjustable parameter, which is often the period of circulation (it always changes when adjustments longitude and corrections inclination) can be regarded as error-free management center of mass of the SPACECRAFT, since the latter do not have time to affect the results of the corrections, as THESE exclude the possibility of their accumulation. However, the use of control (in terms of determining the orbital period) plane, for example, geostationary satellites, traditionally coincides with the plane XOZ inertial geocentric Equatorial coordinate system (the X-axis to the point Spring) when conducting daily corrections and HILDREN, it is not possible t is updated to exclude the methodical error of the calculation of the period of circulation and its changes for the correction the first of which can greatly affect the quality of the process of keeping the AC. The error δ t₁determine the sidereal period is estimated means for trajectory measurements in 0.1 s; the change of the period for correction [mood] of the orbit on the day is nominally (1-2), and refinement of the accelerations from the engines (relative error, according to method 1, 5%) makes it possible respectively to rely on the accuracy Δ2 knowledge [change] period of not more than 0.1 s AND δ t and δ t₂- size small, but the actual deviation of the sidereal orbital period from the expected amounts to 1.5 C. the Reason is explained in this example. If the middle of the active site (AU) corresponds to time t_AUand the intersection of the plane XOZ, the sidereal orbital period is traditionally taken as the control corresponds to the time t_XOZoff-t_AUon the bottom half (the sidereal period of the prior correction believe is true), we obtain the sidereal period, which will include only half implemented for the correction of the average speed of the SPACECRAFT, and at close values of t_AUand t_Zwhen t_XOZ>t_AUin the sidereal period implemented for the correction of the average speed of the SPACECRAFT and will not be reflected. And plan of correction is necessary for each and every day. The specified accuracy of 100% (1,5 who), of course, unacceptable, and if we're talking about geostationary satellites, does not allow to count on the hold narrow areas and conduct a thin collocation (hold multiple SPACECRAFT in one area). This error leads to the fact that the link is only one DK in step adjustments, consisting of the work of this DK, calculated according to HILDREN (best option refinement of thrust) often differs from the actual prescribed by the manufacturer more than the amount prescribed by the same manufacturer (for example, more than 11% of the nominal value for the stationary plasma DK). This error, though not fully, occurs in the calculation of the correction parameters because of perceptions that immediately after the time of intersection of the reference plane must AY that implemented the momentum of the whole must go to the corresponding change in the orbital period. In the Appendix shows an example in which from the WELL produced: prediction of parameters of passive motion of the center of mass of the SPACECRAFT for two days; forecasting the parameters of motion of the center of mass of the SPACECRAFT with thrust on AU, located just behind the t_Z(1)predicting the parameters of motion of the center of mass of the SPACECRAFT with thrust on AU, located midway between t_XOZ(1)and t_XOZ(2)predicting the parameters of motion of the center of mass of the SPACECRAFT with thrust on AU, located directly in front of t . Time t_XOZ(0)coincides with the time WELL.

Plus all of the above is the forecast error of the points of intersection of the reference plane because of the inaccuracy of the knowledge thrust DK.

HILDREN do not allow, even with a rough knowledge rods DK, accumulate error management center of mass of the SPACECRAFT. However, the quality control is directly related to the requirements of maintaining satellite systems during normal operation of the SPACECRAFT. A rough knowledge of the rods DK leads to gross errors of forecasting the motion of the SPACECRAFT, which does not allow using corrections to rely on a high quality realization of the evolution of the SPACECRAFT in orbit.

The aim of the invention is to provide a reliable and rapid method for determining the thrust DK and improving the accuracy of the correction parameters of movement of the center of mass of the SPACECRAFT.

This goal is achieved by testing DK KA, namely, that exert a corrective influence by incorporating DK; conduct daily trajectory measurements; determine the parameters of the motion of the center of mass of the SPACECRAFT; selected, for reasons of stability of the systematic component of the error draughts DK, the interval of time trying to enter statistics on developments DK - actual duration and conditional non DK, and changes in the orbital period of the AC; from the existing data set, choose those that meet the river the view of following one after the other inclusions of the same DK; data summarize and calculate the average thrust for each working DK; make the test stimulus to the body KA successive inclusions of two DK opposite direction thrust equal pulses, the difference from zero of the implemented increment period is transferred to the residual error for the total impulse, which contribute equally with opposite sign in the implemented pulses, and get the correct levels draughts working DC.

Implementation of the proposed method involves the following sequence of operations.

1. Worked out a plan of corrections. This operation is similar to the 1 way 2.

2. Spend trajectory measurements.

This operation is similar to the 2 way 2. With an auxiliary (side) navigation trajectory measurements are conducted in a continuous mode.

3. Implementing program to determine the parameters of motion of the center of mass of the SPACECRAFT. The operation is similar to the 3 way 2.

The result is of interest to the orbital period of the SPACECRAFT.

4. Trying to enter data on operating time of the DC - actual duration and conditional number DK, also change the orbital period. When a continuous process ballistic ensure flight KA always have data from previous trajectory measurements.

The accumulation interval data is selected for reasons of stability of the systematic status is engaged errors rods DK. He is about 2 months.

5. From the available data set, choose those that meet the condition of following one after the other inclusions of the same DC.

In the sample will not be accepted include DC, between which happened clarifying the change of the level of thrust.

6. Data summarize and calculate the average thrust for each working

DK.

Traction on the results of measurements of the trajectory calculated by known methods, for example, by the formula [P. E. Eliasberg "introduction to theory of flight satellites, M.: Nauka, 1965]:

$$F_{YN}=\frac{m_{K\mathrm{And}}\cdot {\mu }_{\oplus }\cdot {\displaystyle \sum \Delta }{T}_{Y{N}_i}}{6\pi \cdot R^2\cdot {\displaystyle \sum t_{Y{N}_i}}}$$,

where F_UNIVERSITY- pull DC, N;

Δ_iτ_Onaccordingly, the increment of the orbital period and the duration of JC with conditional number (ln) is the i-th row of data;

m_CA- SPACECRAFT mass, kg;

µ_⊕is the gravitational parameter of the Earth, m³/s²;

R is the radius of the circular orbit, m

The essence of the approach to determining the thrust for change is the orbital period is what if the correction to the N-day interval are held regularly (daily) about the same sidereal time, the same DC and have the same duration, the change in the orbital period affects only the operation of the DC, the difference between the forecast errors of the SPACECRAFT location at HILDREN on the long interval of the data set on the groundwork of DK is equal to zero.

7. Make a test exposure.

For validation of the obtained rods DK and adequacy of the selected data on operating time DC need experimental verification of consistency of rods mutually opposite DC. Only after such verification with the successful outcome of the calculated thrust may be real.

To do this, at the scheduled time carried out directly following each other include two DC mutually opposite directions of thrust is equal to the pulse when the duration of each turn provides the change in the orbital period to the same value.

8. Spend trajectory measurements. This operation is similar to p. 2.

9. Implementing program to determine the parameters of motion of the center of mass of the SPACECRAFT. The results of the determination of the orbital period before and after the test enable DK determine the change in the orbital period δ t_MESM.

The operation is similar to PP.3, 4.

10. Define the residual error for the total momentum of the Yaga.

The discrepancy ΔJ determined by the ratio of:

$$\Delta J=\frac{m_{K\mathrm{And}}\cdot {\mu }_{\oplus }\cdot \Delta T_{mecm}}{6\pi \cdot R^2}$$.

11. The discrepancy ΔJ contribute equally with opposite sign in the implemented pulses and receive significant levels of linkage DK worked.

Significant levels of rods running DK is obtained from the relations:

$$F_{docm.YN1}=F_{YN1}+\frac{\Delta J}{2t_{mecm.1}}$$for one DK of the pair and

$$F_{docm.YN2}=F_{YN2}+\frac{\Delta J}{2t_{mecm.2}}$$for another DK of the pair.

Next paragraphs.1-10 are repeated during the whole time the AC for its intended purpose.

It should be noted.

1. DL the successful implementation of the plan of correction requires not only good knowledge of the thrust DK (same - changes of the adjustable parameter of the movement), but accurate prediction of motion parameters at the moment of calculation of the correction parameters. All motion parameters at any given time are determined by the oscillating, i.e., the instantaneous current. In addition to our interest period. It is important to bear in mind everything that was said above about the position of the reference plane. However, this goes beyond the testing center and relates to the correction method of the orbital parameters. Yes, exactly the current period are dealing with, we do not know, but the change in the orbital period for correction of the same DK know, therefore, know good traction DK, and this, in the end, turns out to be the most important in the realization of ballistic flight support KA.

2. After determining reliable values of the levels of the pair of rods DK you can use the entire dataset for these DK, except adjacent data on other DK, for further clarification, and, importantly, the data obtained can be used in the event of a change in the regime of ballistic flight support KA, which is described in method 2, i.e., when the trajectory measurements (ITP) is held once a week and less.

The proposed method of testing DK KA allows you to define thrust (control acceleration without the unnecessary costs and precisely what thew, sequentially, as needed, for each DC.

The testing engine of correction of the SPACECRAFT (SC), namely, that exert a corrective influence by including engines correction (DC), is carried out daily trajectory measurements, determine the parameters of the motion of the center of mass of the SPACECRAFT at the time interval selected for reasons of stability of the systematic component of the error draughts DK, collect statistics on developments DK - actual durations of work and contingent DK rooms, as well as changes in the orbital period of the SPACECRAFT, from the available data set, choose those that meet the condition of following one after the other inclusions of the same DK, the selected data summarize and calculate the average thrust for each working DK, make a test exposure to the chassis KA equal pulses by successive inclusions of two DK opposite direction of thrust, the difference from zero of the implemented increment period is transferred to the residual error for the total impulse, which contribute equally with opposite sign in the implemented pulses, and get the correct levels rods worked DK.