CN104504188B - A kind of great-jump-forward reentry vehicle aiming point dynamic adjusting method - Google Patents

Abstract

The invention discloses a kind of great-jump-forward reentry vehicle aiming point dynamic adjusting method.Dimensionless forward speed U is calculated according to the secondary reentry point speed of prediction and calculation and path angle ₁; Ultimate run R is calculated according to vehicle lift-drag and minimum angle of heel data ₁; According to the minimum voyage R of secondary reentry stage overload calculation of design parameters ₂; Voyage ability level R is reentered according to corridor calculation of design parameters secondary; According to secondary reentry point distance parachute-opening point wait fly apart from R _tGand secondary reenters voyage ability level R, calculate dynamic conditioning amount Δ R.The present invention utilizes parsing means fast prediction secondary reentry stage voyage ability, achieves being connected of first reentry stage and secondary reentry stage, reduces numerical prediction calculated amount, improve parachute-opening point control precision.Can be convenient to use in the guidance of little lift-drag ratio aircraft second cosmic velocity ablated configuration.

Description

A kind of great-jump-forward reentry vehicle aiming point dynamic adjusting method

Technical field

The present invention relates to a kind of skip vehicle aiming point dynamic adjusting method, particularly before first re-entry flight device jumps out atmospheric envelope, the computing method of voyage are expected in Guidance Law adjustment, can directly apply to reenter the rear reentry guidance utilizing lift adjustment to realize the aircraft of Jump probability higher than local circular orbital velocity.

Background technology

It is high that lunar exploration returns aircraft speed, and when arriving near the earth (below 120km, after entering dense earth atmosphere), its ground velocity will much larger than local circular orbital velocity.For this type of aircraft, even if lift-drag ratio own is less, still can realize larger air mileage by Jump probability, thus ensure the geometrical-restriction relation between reentry point and recovery site.When selecting Jump probability, there is larger benefit for the peak value premature beats of reentry stage trajectory, peak heat current control.But realize the great-jump-forward reentry trajectory of little lift-drag ratio aircraft, propose higher requirement to GNC system, need the mission phase aircraft speed is higher to adjust rapidly voyage ability, the voyage that guarantee ability can reach and range-to-go match.

In order to solve the problem, the most effective scheme adopts numerical prediction-bearing calibration at present.But numerical prediction can bring larger computation burden to device borne computer, particularly at first reentry stage, if adopt the method for numerical prediction to calculate final drop point, computing cost can be caused to double according to conservative estimation above.Therefore, reducing numerical prediction calculated amount to greatest extent, is the feasible important prerequisite of assured plan.

Main target due to first reentry stage ensures that returning aircraft can arrive drop point at secondary reentry stage, and secondary reentry stage itself also can realize voyage control by the adjustment of angle of heel.As long as therefore first reentry stage is by the energy damping of Reentry vehicles to certain level, remaining accurate adjustment is whole can have been come by secondary reentry stage guidance.

Summary of the invention

Technical matters to be solved by this invention is: overcome the deficiencies in the prior art, provides a kind of great-jump-forward reentry vehicle aiming point dynamic adjusting method, utilizes the secondary reentry point information of numerical prediction to estimate secondary reentry stage voyage ability fast.Outstanding advantages of the present invention is, by means of only the secondary reentry point velocity information (velocity magnitude, velocity reversal) predicted by two analytic sensitivity and a linear combination computing formula, the voyage of secondary reentry stage can be calculated fast, necessary adjustment can be carried out to the aiming point of first reentry stage according to this voyage information, thus ensure that aircraft has comparatively ideal energy-voyage relation when entering secondary reentry stage.

The present invention includes following technical scheme:

A kind of great-jump-forward reentry vehicle aiming point dynamic adjusting method, is characterized in that, comprise the steps:

(1) according to the secondary reentry point speed V of numerical prediction, path angle γ, dimensionless forward speed U is calculated ₁;

(2) according to vehicle lift-drag λ and minimum angle of heel σ _mincalculate ultimate run R ₁;

(3) minimum voyage R is calculated according to secondary reentry stage overload design parameter A ₂;

(4) according to corridor design parameter K ₁, K ₂, K ₃calculate secondary and reenter voyage ability level R;

(5) according to secondary reentry point distance parachute-opening point wait fly apart from R _tGand secondary reenters voyage ability level R, calculate dynamic conditioning amount Δ R.

For realizing the dynamic conditioning of secondary reentry point voyage, first need the voyage ability estimating secondary reentry stage according to secondary reentry point state (speed, path angle, lift-drag ratio situation).For this reason, need to estimate its ultimate run ability and minimum horizontal Cheng Nengli, thus realized the estimation of voyage ability by simple algebraic method.Its computing method are as follows:

According to secondary reentry point predetermined speed V, path angle γ, calculates dimensionless forward speed U ₁, its computing formula is as follows

$U_1=\frac{V\cos \left(\mathrm{\γ}\right)}{7900}$

When considering that aircraft flies with maximum lift-drag ratio, voyage farthest can be realized.If aircraft nominal lift-drag ratio is λ and minimum angle of heel σ _min, ultimate run R can be calculated ₁as follows

$R_1=3185.5\mathrm{\λ}\cos \left({\mathrm{\σ}}_{\min }\right)\ln \frac{0.9998}{1-U_1^2}$

Consider secondary reentry stage overload design parameter A, then can calculate minimum voyage R ₂, its computing formula is as follows:

$R_2=\frac{3185.5(U_1^2-1.6\×{10}^{-4})}{A}$

Utilize R ₁, R ₂, according to corridor design parameter K ₁, K ₂, K ₃calculate secondary and reenter voyage ability level R, its computing formula is as follows:

R＝K ₁R ₁+K ₂R ₂+K ₃

Wherein K ₁, K ₂value is 0.20 ~ 0.85, meets K ₁+ K ₂the design constraint of ≈ 1, K ₃value is

-100000 ~-20000, above-mentioned span and aircraft characteristic, task voyage and relevant, need to combine emulation and confirm;

Consider the secondary reentry point distance parachute-opening point of prediction wait fly apart from R _tGand secondary reenters voyage ability level R, calculate dynamic conditioning amount Δ R, its computing formula is as follows:

ΔR＝R _TG-R

The present invention compared with prior art tool has the following advantages:

For great-jump-forward reentry guidance, if adopt the means of pure values to arrive final drop point at first reentry stage, the computational burden of device borne computer greatly can be increased.Although this kind of mode can improve precision of prediction, for first reentry stage, this kind of precision improvement meaning is relatively little.If by the prediction trajectory of first reentry stage by secondary reentry point, then the follow-up ability that can fly just must calculate (estimation) fast.The present invention meets the demand of rapidity and precision of prediction simultaneously, can be applied in relevant issues easily.

Accompanying drawing explanation

Fig. 1 is the inventive method realization flow figure;

Fig. 2 is that the parachute-opening point that the inventive method realizes scatters situation;

Fig. 3 is the parachute-opening point distribution situation of secondary reentry point not being carried out to dynamic conditioning.

Embodiment

Just by reference to the accompanying drawings the present invention is described further below.

The present invention is directed to great-jump-forward reentry vehicle, give the computing method that a kind of first reentry stage estimates secondary reentry stage voyage fast.

Use the method for numerical prediction, on the device returning aircraft, computing machine can utilize current navigation position, speed, extrapolates the Position And Velocity of secondary reentry point.If still adopt Numerical Predicting Method, although can be easy to obtain drop point site, need to consume the large measuring device borne computer time.For this reason, need to utilize the method estimated fast, sacrifice a part of forecast precision, obtain the lifting of whole efficiency.

First, according to secondary reentry point predetermined speed V, path angle γ, calculates dimensionless forward speed U ₁, its computing formula is as follows

$U_1=\frac{V\cos \left(\mathrm{\γ}\right)}{7900}$

Be λ and minimum angle of heel σ according to aircraft nominal lift-drag ratio _min, ultimate run R can be calculated ₁as follows

$R_1=3185.5\mathrm{\λ}\cos \left({\mathrm{\σ}}_{\min }\right)\ln \frac{0.9998}{1-U_1^2}$

Consider secondary reentry stage overload design parameter A (value of the present invention is 5 ~ 10g scope), then can calculate minimum voyage R ₂, its computing formula is as follows:

$R_2=\frac{3185.5(U_1^2-1.6\×{10}^{-4})}{A}$

Utilize R ₁, R ₂, according to corridor design parameter K ₁, K ₂, K ₃calculate secondary and reenter voyage ability level R, its computing formula is as follows:

R＝K ₁R ₁+K ₂R ₂+K ₃

Finally, consider the secondary reentry point distance parachute-opening point of prediction wait fly apart from R _tGand secondary reenters voyage ability level R, calculate dynamic conditioning amount Δ R, its computing formula is as follows:

ΔR＝R _TG-R

According to the dynamic conditioning amount Δ R that aforementioned formula is calculated, can by secondary reentry point wait fly to carry out front and back adjustment apart from (from secondary reentry point to the great circle arc length of parachute-opening point expected).Then have after adjustment

R _TG ⁺＝R _TG ^--ΔR

Wherein subscript+-represent the distance to be flown before adjusting rear and adjustment respectively.

For the conceptual design of certain type great-jump-forward reentry vehicle, in conjunction with result of mathematical simulation, the mode of statistics can be utilized to obtain parameter K ₁, K ₂k ₃span, get K here ₁=0.3, K ₂=0.7, K ₃=-60000.The validity of the inventive method can be verified by Monte-Carlo method emulation.First carry out simulating, verifying to this method, its parachute-opening point control precision as shown in Figure 2.In order to compared with the method, consider not carry out dynamic conditioning to secondary reentry point, the secondary reentry point position namely requiring first reentry stage to aim at all the time to preset, then its parachute-opening point control precision as shown in Figure 3.Comparison diagram 2 and Fig. 3 can find, when dynamic conditioning not being carried out to secondary reentry point, impact dispersion can amplify largely, namely due to after first re-entry flight, the speed of arrival secondary reentry point has distribution (relative to design point) to a certain degree, even if arrive approximately uniform position, also can bring the larger difference of secondary reentry stage trajectory form, therefore needing secondary reentry stage to carry out the demand of ACTIVE CONTROL will be stronger.And after secondary reentry point is carried out dynamic conditioning, above-mentioned speed is scattered the impact brought and can be compensated by voyage adjustment.For comparatively straight trajectory, due to larger voyage may be obtained, therefore need the distance to be flown increasing secondary reentry stage; And for comparatively precipitous trajectory, then obtainable voyage can reduce, just need the distance to be flown reducing secondary reentry stage.

The unspecified part of the present invention belongs to general knowledge as well known to those skilled in the art.

Claims (1)

1. a great-jump-forward reentry vehicle aiming point dynamic adjusting method, is characterized in that performing step is as follows:

(1) according to the secondary reentry point speed V of numerical prediction, path angle γ, dimensionless forward speed U is calculated ₁, computing formula is as follows

$U_1=\frac{Vcos\left(\mathrm{\γ}\right)}{7900};$

(2) according to the U obtained in step (1) ₁, vehicle lift-drag λ and minimum angle of heel σ _mincalculate ultimate run R ₁;

Computing formula is as follows

$R_1=3185.5\mathrm{\λ}cos\left({\mathrm{\σ}}_{\min }\right)ln\frac{0.9998}{1-U_1^2};$

(3) according to the U obtained in step (1) ₁, precalculated secondary reentry stage overload design parameter A, calculate minimum voyage R ₂;

Computing formula is as follows:

$R_2=\frac{3185.5(U_1^2-1.6\×{10}^{-4})}{A}$

(4) according to design parameter K ₁, K ₂, K ₃calculate secondary and reenter voyage ability level R;

Computing formula is as follows:

R＝K ₁R ₁+K ₂R ₂+K ₃

Wherein K ₁, K ₂value is 0.20 ~ 0.85, meets K ₁+ K ₂the design constraint of ≈ 1, K ₃value is-100000 ~-20000, and above-mentioned span and aircraft characteristic, task voyage are relevant, need to combine emulation and confirm;

(5) according to secondary reentry point distance parachute-opening point wait fly apart from R _tGand secondary reenters voyage ability level R, calculate dynamic conditioning amount Δ R, Δ R=R _tG-R.