CN105302158B - Unmanned plane air refuelling shortest time congregation method based on Dubins paths - Google Patents

Abstract

The invention discloses a kind of unmanned plane air refuelling shortest time congregation methods based on Dubins paths, belong to aircraft flight control technology field.Fuel charger waits unmanned plane is close to refuel according to fixed Route reform, and unmanned plane receives air refuelling instruction, and autonomous flight to fuel charger rear completes congregation task and carries out docking oiling again.The present invention contributes to unmanned plane to fly to estimated meeting point with shortest path, in case of emergency can be merged into row air refuelling with minimum time loss completion, it is ensured that the execution of task and the flight safety of unmanned plane.

Description

Shortest time rendezvous method for aerial refueling of UAV based on Dubins path

technical field

The invention relates to a rendezvous method for aerial refueling of unmanned aerial vehicles, specifically a rendezvous method for aerial refueling of unmanned aerial vehicles based on the Dubins path in the shortest time, and belongs to the technical field of aircraft flight control.

Background technique

Air refueling technology is mainly divided into hose type refueling technology and hard tube type refueling technology. The hose-type air refueling equipment, also known as the hose-drogue refueling system, was first manufactured by British Airways on the basis of inheriting the work of its predecessors. Adopt this method to carry out aerial refueling, only need adorn a fixed or telescopic oil receiving pipe on nose or wing leading edge and get final product. The refueling equipment is composed of a 20-30m long hose and a funnel-type taper sleeve. The entire aerial refueling process can be divided into four main stages: rendezvous, docking, refueling and separation. The main task of the rendezvous phase is to control the UAV to reach a certain refueling airspace with the help of the rendezvous guidance and control system, and require the final speed and heading of the UAV to be consistent with the speed and heading of the tanker. The rendezvous between aerial refueling UAV and tanker is a problem of aircraft guidance and control in three-dimensional space. The rendezvous as the first stage of aerial refueling is the basis for the safe and smooth completion of aerial refueling missions.

In the rendezvous phase of aerial refueling, after receiving instructions, the UAV will fly from other airspaces to the designated airspace for refueling according to a certain route. In order to achieve this goal, it is necessary to study the rendezvous routes of UAVs and tankers under different initial position conditions, design guidance laws to guide UAVs to fly target airspace, and design UAV flight control systems to accurately track guidance commands. When encountering an emergency and requiring the UAV to rendezvous with the tanker in the shortest possible time, it is necessary to design a corresponding route optimization plan to ensure timely rendezvous. Since it is difficult to establish an accurate UAV model, it is necessary to improve the anti-interference ability, dynamic performance and robust performance of the UAV control system to ensure the performance of the closed-loop system and meet the stability requirements. In the existing technology, it is difficult to guarantee the rendezvous between the UAV and the tanker in the shortest time, and the normal fuel supply cannot be carried out, which affects the mission execution and flight safety of the UAV.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a rendezvous method for UAV air refueling in the shortest time based on the Dubins path, so as to realize the rapid supply of fuel for the UAV.

In order to solve the above-mentioned technical problems, the UAV air refueling rendezvous method in the shortest time based on Dubins path provided by the present invention comprises the following steps:

Step 1), the UAV obtains the position and speed information of the tanker, and sets a certain point on the fixed straight-line route of the tanker as the expected meeting point (x _REN , y _REN ) with the tanker, and refuels in the ground coordinate system It takes time T _T for the machine to reach this point;

Step 2), the UAV calculates a shortest path Path _D from the relative position of the UAV (x _R , y _R ) to the expected rendezvous point (x _REN , y _REN ) with the tanker through the Dubins path calculation module, and then Obtain the time T _R that will be consumed by the UAV to reach the expected rendezvous point;

Step 3), if T _R =T _T , then directly output the Dubins path guidance point, and then execute step 4); if T _R ≠T _T , update the estimated rendezvous cost of the UAV according to the time difference Δt=T _R -T _T When T=T _R ±Δt, update the expected rendezvous point (x _REN , y _REN ) on the fixed route of the tanker, and the time spent by the tanker to reach this point T _T =T, repeat step 2) to get the arrival of the UAV again The time T _R to be consumed by the estimated rendezvous point (x _REN , y _REN ) after the tanker is updated, until T _R =T _T and then output the Dubins route guidance point;

Step 4), the UAV tracks the Dubins path navigation point until the UAV arrives at the rendezvous point and rendezvous with the refueling aircraft.

In the present invention, in the above-mentioned step 1), the time-consuming time for the tanker to reach the expected meeting point under the ground coordinate system:

In the formula, (x _REN , y _REN ) is the expected rendezvous point, (x _T , y _T ) is the relative position of the tanker, and V _T is the flight speed of the tanker.

In the present invention, the concrete process of above-mentioned step 2) is as follows:

Step 21), according to the relative position coordinates, heading angle and flight speed of the tanker and the UAV, the expected meeting point (x _REN , y _REN ), the minimum turning radius limit R _min of the UAV, and calculate the flight distance between the UAV and the UAV. Velocity V _R at the relative position of the UAV (x _R , y _R ) is tangent to the left circle and right circle and the tanker flight speed V _T is tangent to the left circle and right circle at the expected meeting point (x _REN , y _REN ) Combination, select the group with the smallest center-to-center distance in the combination as the arc of Dubins;

Step 22), according to the combination of arcs, calculate a Dubins path starting from the relative position of the drone (x _R , y _R ) and ending at the expected meeting point (x _REN , y _REN ) as the shortest path Path _D ; The path length L is the sum of the lengths of the starting arc, the ending arc and the common tangent line between the two arcs;

Step 23), divide the path length L by the flight speed V _R of the UAV to obtain the time-consuming time to reach the expected rendezvous point as T _R .

In the present invention, x _REN = x _T + V _T T _T cos χ _T , y _REN = y _T + V _T T _T sin χ _T in the above step 3).

The beneficial effects of the present invention are: by selecting the expected meeting point on the fixed route of the tanker, calculating the Dubins shortest path for the drone to reach the meeting point according to the initial position of the drone, and comparing the arrival of the tanker and the drone to the expected meeting point The length of time, and then update the rendezvous point until the condition of equal time is met, that is, find a Dubins shortest path to the expected rendezvous point, and give the navigation waypoint, which reduces the time consumption in the rendezvous process of aerial refueling, which is helpful for UAVs The rendezvous refueling can be quickly completed in emergency situations where refueling is required, so as to continue the mission and ensure the flight safety of the UAV.

Description of drawings

Fig. 1 is the flow chart of the shortest time rendezvous method for aerial refueling of unmanned aerial vehicle based on Dubins path in the present invention;

Fig. 2 is the calculation schematic diagram of Dubins path among the present invention;

Figure 3 is a schematic diagram of the structure of the guidance and control system of the UAV.

Detailed ways

The technical solution of the present invention will be further described in detail below in conjunction with the accompanying drawings.

As shown in Figure 1, the shortest time rendezvous method for aerial refueling of unmanned aerial vehicles based on the Dubins path in the present invention is mainly aimed at the refueling process between the refueling process between the refueling aircraft and the unmanned aerial vehicles that are installed with inertial navigation units to obtain speed and position information and can communicate. meeting, including the following steps:

Step 1. After the UAV receives the aerial refueling mission command, it enters the rendezvous tracking mode, and the refueling aircraft maintains a fixed flight route and waits to rendezvous with the UAV;

Step 2. The tanker establishes a communication connection with the UAV, and obtains its own position and speed information through the airborne equipment and sends it to the UAV;

Step 3. The UAV receiving module obtains the position and speed information of the tanker, and sets a certain point on the fixed straight-line route of the tanker as the expected meeting point (x _REN , y _REN ), and it takes T _T for the tanker to reach this point:

In the formula, (x _REN , y _REN ) is the expected rendezvous point, (x _T , y _T ) is the relative position of the tanker, and V _T is the flight speed of the tanker;

Step 4. As shown in Figure 2, during the flight, the relative position of the tanker in the plane under the inertial space at the initial moment is (x _T , y _T ), the initial heading angle of the tanker is χ _T , and the plane follows a fixed route with a constant speed Fly at a fixed altitude. The relative position of the UAV in the plane in the inertial space at the initial moment is (x _R , y _R ), the initial heading angle of the UAV is χ _R , and the minimum turning radius is limited to R _min . The tanker flies on a fixed or predictable route, such as a straight route, at a constant speed, and after a period of time T _T the tanker flies to a certain position (x _T , y _T ) _TT on its expected trajectory, which is the expected meeting point (x _REN , y _REN ), the heading angle of the tanker is χ _T , based on which the left circle and the right circle tangent to the flight speed V _R of the drone at the relative position (x _R , y _R ) of the drone and the tanker tanker The combination of the left circle and the right circle tangent to the flight speed V _T at the expected meeting point (x _REN , y _REN ):

The coordinates of the center of the left circle at the starting point are: y _RL = y _R - R _min cosχ _R , x _RL = x _R + R _min sinχ _R ;

The coordinates of the center of the right circle at the starting point are: y _RR ＝y _R +R _min cosχ _R , x _RR ＝x _R -R _min sinχ _R ;

The coordinates of the center of the left circle at the end point are: y _TL = y _T - R _min cosχ _T , x _TL = x _T + R _min sinχ _T ;

The coordinates of the center of the right circle at the end point are: y _TR = y _T + R _min cosχ _T , x _TR = x _T - R _min sinχ _T ;

According to the different combinations of the left and right circles at the starting point and the end point, the center distances L _LSL , L _LSR , L _RSL , L _RSR are calculated, and the shortest center distance L _min corresponds to the combination of the arc-tangent-arc of the shortest Dubins path. The centers of the starting and ending circles of the Dubins path are also obtained from this.

Find the starting point coordinates (x _TGI , y _TGI ) and end point coordinates (x _TGF , y _TGF ) of the tangent line according to the starting circle (x _I , y _I ) and ending circle (x _F , y _F ).

LSL combination:

LSR combination:

RSL combination:

RSR combination:

Finally, the Dubins path is obtained from a section of arc C _I from the relative position of the drone (x _R , y _R ) to the starting point coordinates (x _TGI , y _TGI ), from the starting point coordinates (x _TGI , y _TGI ) to the end point coordinates ( x _TGF , y _TGF ) is composed of a straight line S and a circular arc C _F from the coordinates of the end point (x _TGF , y _TGF ) to the expected meeting point (x _REN , y _REN ), the length of the Dubins path is L=C _I +C _F +S, that is, the sum of the lengths of the starting arc, the ending arc and the common tangent between the two arcs.

Calculate the time T _{R consumed by the UAV to fly through the Dubins path at the flight speed V R ,}

Step 5. The time T T for the tanker to reach the expected meeting point (x _REN , y _REN ) and the time _{T R} for the UAV to reach the expected meeting point (x _REN , y _REN ), if T _T =T _R means, If the UAV and tanker arrive at the same time, the expected rendezvous point (x _REN , y _REN ) on the expected trajectory of the tanker is the final rendezvous point;

If T _T ≠T _R , the time needs to be updated. According to the time difference between the UAV and the tanker arriving at the expected rendezvous point (x _REN , y _REN ), Δt=T _R -T _T , update the UAV’s estimated rendezvous time T= T _R +Δt, update the expected rendezvous point x _REN ＝ x _T + V _T T _T cosχ _T , y _REN = y _T + V _T T _T sinχ _T on the fixed route of the tanker, and the time spent by the tanker to reach this point T _T =T. Re-calculate the Dubins path according to step 4 and then compare T _T and T _R until T _T = T _R , output the Dubins path navigation point;

Step 6, as shown in Figure 3, the starting point coordinates (x _TGI , y _TGI ), the end point coordinates (x _TGF , y _TGF ) and the expected rendezvous point (x _REN , y _REN ) of the navigation path point on the Dubins path are used as UAV The tracking target is input into the UAV's proportional guidance module, and the proportional guidance module calculates the UAV's attitude angle control signal, which is input into the UAV's attitude control system. The attitude control system outputs the rudder surface control signal of the UAV, so as to complete the tracking of the attitude angle control signal, track the navigation path point of the calculated Dubins path, and control the UAV to fly to the expected rendezvous point to complete the rendezvous task with the tanker .

Those skilled in the art can understand that, unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It should also be understood that terms such as those defined in commonly used dictionaries should be understood to have a meaning consistent with the meaning in the context of the prior art, and will not be interpreted in an idealized or overly formal sense unless defined as herein explain.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (4)

1. a kind of unmanned aerial refueling rendezvous method based on the shortest time of Dubins path, it is characterized in that comprising the following steps: Step 1), the UAV obtains the position and speed information of the tanker, and sets a certain point on the fixed straight-line route of the tanker as the expected meeting point (x _REN , y _REN ) with the tanker, and refuels in the ground coordinate system It takes time T _T for the machine to reach this point; Step 2), the UAV calculates a shortest path Path _D from the relative position of the UAV (x _R , y _R ) to the expected rendezvous point (x _REN , y _REN ) with the tanker through the Dubins path calculation module, and then Obtain the time T _R that will be consumed by the UAV to reach the expected rendezvous point; Step 3), if T _R = T _T , then directly output the Dubins path guidance point, and then perform step 4); if T _R ≠ T _T , update the expected rendezvous of the UAV according to the time difference △ t = T _R -T _T Time-consuming T = T _R ± △ t, update the expected rendezvous point (x _REN , y _REN ) on the fixed route of the tanker, and the time-consuming T _T = T for the tanker to reach this point, repeat step 2) to regain unmanned The time T _R it takes for the tanker to arrive at the estimated rendezvous point (x _REN , y _REN ) after the tanker is updated, until T _R = T _T and then output the Dubins route guidance point; Step 4), the UAV tracks the Dubins path navigation point until the UAV arrives at the rendezvous point and rendezvous with the refueling aircraft. 2. according to claims 1, based on the unmanned aerial vehicle refueling method of Dubins path in the shortest time rendezvous, it is characterized in that: in the described step 1), under the ground coordinate system, the fuel tanker arrives at the estimated time consumption of the rendezvous point: <mrow><msub><mi>T</mi><mi>T</mi></msub><mo>=</mo><mfrac><msqrt><mrow><msup><mrow><mo>(</mo><msub><mi>x</mi><mrow><mi>R</mi><mi>E</mi><mi>N</mi></mrow></msub><mo>-</mo><msub><mi>x</mi><mi>T</mi></msub><mo>)</mo></mrow><mn>2</mn></msup><mo>+</mo><msup><mrow><mo>(</mo><msub><mi>y</mi><mrow><mi>R</mi><mi>E</mi><mi>N</mi></mrow></msub><mo>-</mo><msub><mi>y</mi><mi>T</mi></msub><mo>)</mo></mrow><mn>2</mn></msup></mrow></msqrt><msub><mi>V</mi><mi>T</mi></msub></mfrac></mrow> In the formula, (x _T , y _T ) is the relative position of the tanker, and V _T is the flight speed of the tanker. 3. according to claims 1 or 2 described based on the unmanned aerial vehicle refueling shortest time rendezvous method of Dubins path, it is characterized in that described step 2) the concrete process is as follows: Step 21), according to the relative position coordinates, heading angle and flight speed of the tanker and the UAV, the expected meeting point (x _REN , y _REN ), the minimum turning radius limit R _min of the UAV, and calculate the flight distance between the UAV and the UAV. The left circle and the right circle tangent to the speed V _R at the relative position of the drone (x _R , y _R ) and the left circle and right circle tangent to the flight speed V _T of the tanker at the expected meeting point (x _REN , y _REN ) The combination of , select the group with the smallest center-to-center distance in the combination as the arc of Dubins; Step 22), according to the combination of arcs, calculate a Dubins path starting from the relative position of the drone (x _R , y _R ) and ending at the expected meeting point (x _REN , y _REN ) as the shortest path Path _D ; The Dubins path length L is the sum of the lengths of the starting arc, the ending arc and the common tangent line between the two arcs; Step 23), divide the path length L by the flight speed V _R of the UAV to obtain the time-consuming time to reach the expected rendezvous point as T _R . 4. according to the described rendezvous method of the UAV aerial refueling shortest time based on Dubins path according to claims 3, it is characterized in that x _REN =x _T +V _T T _T cosχ _T , y _REN = in described step 3) y _T +V _T T _T sinχ _T , x _T , y _T is the relative position of the tanker, V _T is the flight speed of the tanker, χ _T is the heading angle of the tanker.