CN103486905B - Determining method for terminal guidance shift-exchange conditions of reenter vehicle - Google Patents

Abstract

A method for determining handover conditions for the terminal guidance of a re-entry vehicle, (1) generating preset handover point information; (2) correcting the preset handover point information generated in step (1), and generating preset handover point error balls; (3) Design the guidance gain that changes with time; (4) Determine the sequence of order smoothing time coefficients sorted by time; (5) Determine the shift logic; when the shift logic is fully satisfied, the seeker end guidance starts; During the guidance flight process of entering the aircraft, use the time-varying guidance gain determined in step (3) to carry out mid-guidance, and judge in real time whether the shift logic determined in step (5) is satisfied at the same time. When the shift logic is satisfied, start the guidance First and last guidance, and take values from the command smoothing time coefficient sequence determined in step (4) in order, use this coefficient to smooth the middle guidance command and the final guidance command, and use the smoothed command to guide, to achieve After the preset time, it will switch to simple seeker end guidance.

Description

A Method for Determining Shift Conditions of Reentry Vehicle Terminal Guidance

technical field

The invention belongs to the technical field of weapon system design, and relates to a method for determining the shift condition of the terminal guidance of a reentry vehicle. The invention is mainly applied to the design and realization of the transition conditions of the middle and terminal guidance of the reentry precision strike aircraft, so as to ensure the strike precision of the payload.

Background technique

Reentry vehicles have the characteristics of high dynamics and multiple constraints, which are especially important for vehicles with terminal guidance capabilities. A reentry vehicle with terminal guidance capability needs to experience a wide range of speed changes and altitude changes, and the performance requirements for the guidance and control system are relatively strict. In general, different guidance systems are used for intermediate guidance and terminal guidance. After the mid-to-terminal guidance is handed over, the position of the aircraft is measured by the seeker information. Therefore, to ensure the terminal-guidance accuracy conditions and speed and angle constraints, it is necessary to adopt a highly reliable terminal-guidance handover system. Therefore, it is a high-reliability, high-precision flight guidance control mode, which brings many new challenges and difficulties to the control system.

Contents of the invention

The technical problem of the present invention is to overcome the deficiencies of the prior art and provide a method for determining the handover condition of the terminal guidance of the re-entry vehicle.

The technical solution of the present invention is: a kind of reentry aircraft terminal guidance handover condition determination method, the steps are as follows:

(1) According to the given initial re-entry point and strike target information, plan the re-entry trajectory and generate preset shift point information. The shift point information includes the position at the shift time, speed, trajectory inclination, trajectory deflection angle, Line of sight rotation angular rate;

(2) Correct the preset handover point information generated in step (1) according to the working conditions of the reentry vehicle seeker terminal guidance, and generate the preset handover point error ball according to the requirements of navigation positioning accuracy and terminal guidance hit accuracy ;

(3) The guidance and control system of the reentry vehicle before the shift adopts the variable gain tracking guidance law, and the modified preset shift point information in step (2) is used as the terminal constraint to design the guidance gain that changes with time;

(4) According to the guidance command in step (3) variable gain tracking and the guidance control command of the seeker self-seeking, calculate the difference between the two sets of commands and analyze the response of the control system, and determine the command smoothing time coefficient sequence sorted by time;

(5) Determine the shift logic according to the position speed and error ball of the shift point, the line-of-sight rate of the shift point, and the direction of the speed; when the shift logic is fully satisfied, the seeker end guidance is activated;

(6) During the mid-guidance flight of the re-entry vehicle, use the time-varying guidance gain determined in step (3) to carry out mid-guidance, and judge in real time whether the shift logic determined in step (5) is satisfied at the same time. When the shift logic is satisfied , start the seeker end guidance, and take values from the command smoothing time coefficient sequence determined in step (4) in order, use this coefficient to smooth the center guidance command and the end guidance command, and use the smoothed command Guidance is carried out, and after the preset time is reached, it is transferred to simple guidance at the end of the seeker.

The shift logic includes the combination condition of shift point position speed and error sphere and the combination condition of shift point line-of-sight rate and speed direction; wherein the combination condition of shift point position speed and error ball is:

||r ^* -r _c ||<K _r ·||δr _c ||+K _v ·δv _c

Among them, r ^* is the actual position of the aircraft, r _c is the position of the preset handover point corrected in step (2), δr _c is the position error in the error sphere of the preset handover point, and δv _c is the position error in the error sphere of the preset handover point Speed error, K _r , K _v error coefficient; || || represents vector modulo;

Combination conditions of line-of-sight turn rate and speed direction at the shift point are:

cos ^-1 (cosθ ^* cosψ ^* )<K _θ cos ^-1 (cosθ _c cosψ _c )+K _ω (ω _LOS -ω _LOSC )

Among them, θ ^* , ψ ^* are the actual ballistic inclination angle and ballistic deflection angle, θ _c , ψ _c are preset ballistic inclination angles and ballistic deflection angle, K _θ , K _ω are error coefficients.

Compared with the prior art, the present invention has beneficial effects as follows:

(1) The present invention solves the problem of terminal guidance handover under complex conditions, and enhances the fault tolerance of the guidance system. Firstly, the preset shift point information is calculated through the initial information and target information, and it is corrected by using the working conditions of the seeker and terminal guidance. Furthermore, through variable gains, command smoothing coefficients, and multiple conditional judgment logics, steps and mutations in the shift state commands are prevented, the reliability of the weapon system shift is improved, and unnecessary links such as command hardware limits of the weapon system can be reduced.

(2) The method of the present invention can solve the problem of complex and changeable shift conditions of the terminal-guided re-entry aircraft, enhance the robustness of the scheme, and improve the fault-tolerant capability of the guidance system.

(3) The invention designs shift logic with errors to ensure that the state of the aircraft at the shift time meets the capture conditions of the seeker, which provides favorable conditions for the terminal guidance of the weapon system.

(4) In the present invention, the command smoothing coefficient sequence of the terminal guidance handover design order prevents the step and mutation of the handover state order, improves the reliability of the handover of the weapon system, and can reduce unnecessary links such as the command hardware limit of the weapon system.

Description of drawings

Fig. 1 is a flow chart of the method of the present invention;

Fig. 2 is a process diagram of generating and correcting preset shift point information of the present invention;

Fig. 3 is a relational diagram of shift point requirement and design index of the present invention;

Fig. 4 is a diagram of the smoothing work process of the final guidance command in the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

As shown in Figure 1, the present invention relates to a method for determining the handover condition of the terminal guidance of a reentry vehicle, and the specific steps are as follows:

1. Generate preset shift points;

As shown in Figure 2, the reentry constraint boundary (heat flow, overload, dynamic pressure, etc.), through simulation planning, the longitudinal profile of the re-entry vehicle is generated, and the preset handover point information that meets the flight requirements is preliminarily obtained.

The planning of the reentry trajectory can adopt the commonly used reentry trajectory optimization algorithm based on the Gauss pseudospectral method or the sequence quadratic programming algorithm, etc., and use the above algorithm to calculate the position of the shift time speed size Ballistic inclination Ballistic angle Line of sight rotation rate

2. Correct the preset shift point and generate the preset shift point error ball;

After preliminarily obtaining the preset shift point information, consider the constraints of seeker capture conditions, mainly the field of view angle range and line-of-sight angle rotation rate constraints, so as to correct the preset shift point information, and at the same time consider the capture boundary conditions to give a preset Shift point error ball.

The preset handover point information generated by step (1) does not consider the constraints shown in Figure 3, and focuses on the constraints caused by the capture conditions of the seeker on the ballistic inclination angle, ballistic deflection angle, and line-of-sight rotation angular rate. Select the objective function of field of view angle and line-of-sight angle rotation rate in the capture conditions of the seeker, select the ballistic inclination angle, ballistic deflection angle, and line-of-sight rotation angle rate as design variables, and use the quasi-Newton iterative method to use the preset shift generated in step (1) The point is the initial value of the iteration, and the median of the field of view angle and the line-of-sight angle rotation rate range satisfying the capture condition of the seeker is the iteration stop condition, and the correction of the preset handover point information is completed. Take aircraft position r _c , velocity v _c , ballistic inclination angle θ _c , ballistic deflection angle ψ _c , line of sight rotation angular rate ω _LOSC when the iteration stop condition is met as the corrected preset handover point information.

Taking the corrected shift point information as the initial value of the iteration, the other conditions of the above method remain unchanged, and the iteration stop condition is set to meet the upper and lower boundaries of the field of view and line of sight angle rotation rate. The calculated shift point position and speed are consistent with the corrected preset shift Calculate the difference of the point position r _c and velocity v _c to obtain the preset position error δr _c and preset speed error δv _c , which are called error spheres.

3. Design medium guidance with variable gain;

Design the guidance command in the variable gain, the guidance command can take the form of the following formula:

δ _a =K·K _L ·[Δr,Δv] ^T

Among them, Δr and Δv are the difference between the current position and speed of the aircraft and the position and speed of the reference trajectory, K _L is the guidance gain obtained by the LQR method, and K is the variable gain.

Design variable gain K (also known as time-varying guidance gain)

$\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; r</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>}{<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; r</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>}<span\; class="notranslate">\; -</span>\frac{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; v</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; |</span>}{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; v</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; |</span>}$

The gain processing of the center guidance command makes it possible to reach the preset handover point without affecting the flight performance of the center guidance throughout the flight process, and can also take into account the stability requirements of the center guidance command when approaching the handover point.

v ^* represents the actual flight speed, r ^* represents the actual position vector of the aircraft, || || represents the modulus of the vector, and || represents the absolute value.

4. Determine the command smoothing coefficient sequence;

As shown in Fig. 4, according to the standard working condition, according to the guidance command δ _a in the variable gain tracking and the guidance control command δ _b of the seeker self-seeking in step (3), the command smoothing coefficient sequence β function sorted by time is designed

$\mathrm{<span\; class="notranslate">\; \&beta;</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; \&delta;</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; \&delta;</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}$

Among them, t ₀ is the start-up time of the seeker satisfying the shift logic, δ _a (t ₀ ) is the guidance command at this time, and δ _b (t ₀ ) is the last guidance command at this time.

5. Design shift logic;

The shift logic includes two conditions:

The first is the combination condition of shift point position, speed and error ball

||r ^* -r _c ||<K _r ·||δr _c ||+K _v ·δv _c

Among them, r ^* is the actual aircraft position, r _c is the corrected preset handover point position, δr _c is the preset position error, δv _c is the preset speed error, K _r and K _v are error coefficients, which are selected according to experience , for example, for an aircraft whose speed at the handover point is less than Mach 3, K _r usually takes a value of 0.1-3, and K _v is generally 5-10 times of K _r , which are adjusted according to δv _c .

The second is the combination conditions of line-of-sight turn rate and speed direction at the shift point

cos ^-1 (cosθ ^* cosψ ^* )<K _θ cos ^-1 (cosθ _c cosψ _c )+K _ω (ω _LOS -ω _LOSC )

Among them, θ ^* , ψ ^* are the actual ballistic inclination angle and ballistic deflection angle, θ _c , ψ _c are the corrected ballistic inclination angle and ballistic deflection angle, K _θ , K _ω are error coefficients, which are taken according to experience, for example, for the shift point When the line-of-sight rotation angular rate is less than 5°/s, K _r is usually 0.05 to 1, and K _v is generally 3 to 5 times K _r .

When both conditions are met at the same time, the seeker terminal guidance starts.

6. Actual Guidance

During the mid-guidance flight of the re-entry vehicle, use the time-varying guidance gain determined in step (3) to carry out mid-guidance, and judge in real time whether the shift logic determined in step (5) is satisfied at the same time. When the shift logic is satisfied, start the guidance Seeker terminal guidance, and take values from the command smoothing time coefficient sequence determined in step (4) in order, and use this coefficient to smooth the mid-guidance command δ ^* _a and final guidance command δ ^* _b generated by the actual flight, And use the command _δc after smoothing to guide, and after reaching the preset time, turn to the simple guidance of the end of the seeker.

δ _c = β · δ ^* _a + (1-β) · δ ^* _b

Wherein, the preset time may be set to 5ms˜20s according to empirical values. It is also possible to control the time directly according to the sequence of order smoothing time coefficients during design, and switch to simple guidance at the end of the seeker after taking the value in sequence to the last coefficient in the sequence.

In the design of the mid/terminal guidance transition condition of XX, the method for determining the transition condition of the reentry vehicle terminal guidance described in the present invention is used to realize the rapid design of the mid/terminal guidance transition condition of a certain weapon. Through six degrees of freedom simulation verification, it is obtained It is shown that the shift process and shift conditions determined by this method can meet the seeker capture conditions.

Parts not described in detail in the present invention belong to the common knowledge of those skilled in the art.

Claims (2)

1. A re-entry vehicle terminal guidance handover condition determination method is characterized in that the steps are as follows: (1) According to the given initial re-entry point and strike target information, plan the re-entry trajectory and generate preset shift point information. The shift point information includes the position at the shift time, speed, trajectory inclination angle, trajectory deflection angle, Line of sight rotation angular rate; (2) Correct the preset handover point information generated in step (1) according to the working conditions of the reentry vehicle seeker terminal guidance, and generate the preset handover point error ball according to the requirements of navigation positioning accuracy and terminal guidance hit accuracy ; (3) The guidance and control system of the reentry vehicle before the shift adopts the variable gain tracking guidance law, and the modified preset shift point information in step (2) is used as the terminal constraint to design the guidance gain that changes with time; (4) According to the guidance command in step (3) variable gain tracking and the guidance control command of the seeker self-seeking, the difference between the two groups of commands is calculated and the response of the control system is analyzed to determine the sequence of command smoothing time coefficients sorted by time; (5) Determine the shift logic according to the position speed and error ball of the shift point, the line-of-sight rotation rate of the shift point and the speed direction; when the shift logic is fully satisfied, the seeker end guidance is activated; (6) During the mid-guidance flight of the re-entry vehicle, use the time-varying guidance gain determined in step (3) to carry out mid-guidance, and judge in real time whether the shift logic determined in step (5) is satisfied at the same time. When the shift logic is satisfied , start the seeker end guidance, and take values from the command smoothing time coefficient sequence determined in step (4) in order, use this coefficient to smooth the center guidance command and the end guidance command, and use the smoothed command Guidance is carried out, and after the preset time is reached, it is transferred to simple guidance at the end of the seeker. 2. A method for determining shift conditions for reentry vehicle terminal guidance according to claim 1, characterized in that: said shift logic includes shift point position velocity and error ball combination conditions, shift point line-of-sight rotation angular rate and velocity direction Combination conditions; where the combination conditions of shift point position velocity and error ball are: ||r ^* -r _c ||<K _r ·||δr _c ||+K _v ·δv _c Among them, r ^* is the actual position of the aircraft, r _c is the position of the preset handover point corrected in step (2), δr _c is the position error in the error sphere of the preset handover point, and δv _c is the position error in the error sphere of the preset handover point Speed error, K _r , K _v error coefficient; |||| represents vector modulo; Combination conditions of line-of-sight rotation angular rate and velocity direction at the shift point are: cos ^-1 (cosθ ^* cosψ ^* )<K _θ cos ^-1 (cosθ _c cosψ _c )+K _ω (ω _LOS -ω _LOSC ) Among them, θ ^* , ψ ^* are the actual ballistic inclination angle and ballistic deflection angle, θ _c , ψ _c are preset ballistic inclination angles and ballistic deflection angle, K _θ , K _ω are error coefficients.