A formation distance control method

Abstract

The present invention relates to the field of aircraft technology, and discloses a formation distance control method. When performing formation distance control, a ground speed instruction is calculated, and then the ground speed instruction is converted into an airspeed instruction according to the proportional relationship between airspeed and ground speed. The present invention solves the problems of high flight safety risks existing in the prior art.

Description

Technical Field

[0001] The invention relates to the technical field of aircraft, and in particular to a formation distance control method. Background Art

[0002] UAV technology has developed rapidly, and UAV formation technology has also developed rapidly. Multi-UAV formation flight, coordinated reconnaissance, relay communication, electronic countermeasures, battlefield assessment and coordinated strike operations can improve the success rate of single-machine combat missions. For example, in the process of battlefield reconnaissance, the use of multi-machine coordinated reconnaissance can improve the reconnaissance speed and target reconnaissance rate; in the target strike mission, multi-UAV formations coordinate all-round attacks to expand the hit range and increase the lethality and hit probability; in the battlefield assessment process, multi-machine coordination can be used to complete all-round reconnaissance of the target.

[0003] In the actual mission execution process, the formations include trapezoidal, wedge, column, horizontal and V-shaped formations. The safe distance between aircraft needs to be maintained during the maintenance and change of these formations. The flight speed of drones is usually controlled by airspeed, and airspeed control can only indirectly affect the distance control between aircraft, not directly, and cannot guarantee the safe distance between drones when flying in formation. If the method of controlling ground speed is adopted, the flight safety of the drone itself cannot be guaranteed, and the drone is at risk of flying at high ground speed and low airspeed. Summary of the invention

[0004] In order to overcome the deficiencies of the prior art, the present invention provides a formation distance control method to solve the problems of high flight safety risks in the prior art.

[0005] The technical solution adopted by the present invention to solve the above problems is:

[0006] A formation distance control method is provided. When performing formation distance control, a ground speed instruction is calculated, and then the ground speed instruction is converted into an airspeed instruction through the proportional relationship between airspeed and ground speed.

[0007] As a preferred technical solution, the following steps are included:

[0008] S1, determine the coordinate positions of the leading and trailing aircraft;

[0009] S2, determining the relative position and relative speed relationship between the leading aircraft and the trailing aircraft;

[0010] S3, design the formation forward distance controller;

[0011] S4, design formation lateral distance controller;

[0012] S5, design the altitude maintenance controller for the rear aircraft in the formation;

[0013] Among them, the leading aircraft refers to the aircraft located in front of the flight direction on the route, and the following aircraft refers to the aircraft located behind the flight direction on the route.

[0014] As a preferred technical solution, step S1 includes the following steps:

[0015] S11, establish the north-east coordinate system;

[0016] S12, calculating the coordinate value of the front aircraft in the north-east coordinate system;

[0017] S13, calculating the coordinate value of the rear machine in the north-east coordinate system.

[0018] As a preferred technical solution, in step S11, a north-east coordinate system definition is established :Among them, the take-off point of the rear aircraft is the coordinate origin, The axis points due north. The axis points due east horizontally. The axis is perpendicular to the horizontal plane and points to the center of the earth;

[0019] In step S12, the take-off point of the following aircraft is obtained through GPS navigation information. Longitude ,latitude and altitude , the current position of the front aircraft is , the conversion relationship from the longitude and latitude high coordinate system to the north-east ground coordinate system is:

[0020] ;

[0021] In the formula, , , They are respectively the position of the front aircraft in the north-east coordinate system axis, axis, Axis coordinates, , , They are the longitude, latitude and altitude of the preceding aircraft. is the meridian curvature radius of the take-off point of the trailing aircraft, is the radius of curvature of the yoke at the takeoff point of the rear aircraft , and They are the latitude difference, longitude difference, and altitude difference between the preceding aircraft and the reference point, namely:

[0022] ;

[0023] in,

[0024]

[0025]

[0026] In the formula, is the semi-major axis of the Earth ellipsoid, is the eccentricity of the Earth ellipsoid;

[0027] In S13, the longitude of the rear machine is ,latitude and altitude Get the coordinates of the rear aircraft in the north-east coordinate system:

[0028] ;

[0029] In the formula, , , They are respectively the position of the rear aircraft in the north-east coordinate system axis, axis, Axis coordinates, , and They are the latitude difference, longitude difference, and altitude difference between the rear aircraft and the reference point, namely:

[0030] .

[0031] As a preferred technical solution, step S2 includes the following steps:

[0032] S21, calculate the flight path azimuth;

[0033] S22, calculating the relative position relationship between the front machine and the rear machine;

[0034] S23, calculating the relative speed relationship between the leading machine and the trailing machine.

[0035] As a preferred technical solution, in step S22, the relative position vector between the front machine and the rear machine is determined:

[0036] ;

[0037] According to the two adjacent waypoints of the route and Calculate the heading angle of the route ; The coordinates of the waypoints in the north-east coordinates are calculated through the coordinate conversion relationship. and ;

[0038] have:

[0039] ;

[0040] In the formula, , , They are the distances between the front and rear aircraft in the north-east coordinate system. axis, axis, The relative position vector of the axis, are the longitude, latitude and altitude of waypoint A respectively, are the longitude, latitude, and altitude of waypoint B, They are respectively the waypoint A in the north-east coordinate system axis, axis, Axis coordinates, They are respectively the waypoint B in the north-east coordinate system axis, axis, Axis coordinates, atan2 is the four-quadrant inverse tangent function;

[0041] In S22, the relative position vector between the leading aircraft and the trailing aircraft is converted to the flight path:

[0042] ;

[0043] in, is the relative flight path distance between the front and rear aircraft, is the relative lateral distance between the front and rear aircraft, is the relative height between the front and rear aircraft;

[0044] In S23, the speed of the preceding aircraft is obtained from the GPS navigation system. The speed of the rear machine , the relative speed between the front and rear aircraft is :

[0045] ;

[0046] in, They represent the north speed, east speed and ground speed of the leading aircraft respectively. Respectively represent the north speed, east speed and ground speed of the rear aircraft. represents the transpose operation, , , They represent the north speed difference, east speed difference, and ground speed difference between the leading and trailing aircraft respectively;

[0047] Convert to the route direction to get :

[0048] ;

[0049] In the formula, Indicates the forward speed of the leading aircraft relative to the trailing aircraft, Indicates the lateral speed of the leading aircraft relative to the trailing aircraft. Indicates the ground speed of the leading aircraft relative to the trailing aircraft.

[0050] As a preferred technical solution, step S3 includes the following steps:

[0051] S31, calculating the ground speed command of the rear aircraft;

[0052] S32, calculate the airspeed command of the rear aircraft;

[0053] S33, calculating the engine throttle command of the rear engine.

[0054] As a preferred technical solution, step S4 includes the following steps:

[0055] S41, calculate the position and speed of the leading aircraft relative to the route;

[0056] S42, design the front aircraft lateral distance controller;

[0057] S43, design the rear engine lateral distance controller.

[0058] As a preferred technical solution, in S31, an airspeed controller for the rear aircraft is designed based on the ground speed of the leading aircraft, and the output of the airspeed controller for the rear aircraft is the forward ground speed instruction of the rear aircraft:

[0059]

[0060] ;

[0061] In the formula, is the ground speed command of the rear aircraft, is the increment of the rear engine ground speed command, is the relative forward distance feedback coefficient, , They are the proportional coefficient and integral coefficient of speed control respectively. is the forward distance instruction, is the relative flight path distance between the front and rear aircraft, is the forward speed of the rear aircraft;

[0062] In S32, according to the current airspeed and ground speed of the trailing aircraft, the proportional relationship between the airspeed and the ground speed is obtained, which is:

[0063] ;

[0064] Through ground speed conversion, the airspeed command of the following aircraft is obtained:

[0065] ;

[0066] In the formula, is the ratio of the airspeed of the trailing aircraft to the ground speed, is the airspeed of the rear aircraft, is the ground speed of the rear aircraft, is the airspeed command of the following aircraft;

[0067] In S33, the throttle control circuit is used to obtain the throttle command of the engine of the rear engine. :

[0068] ;

[0069] In the formula, , and They are the proportional coefficient, integral coefficient and differential coefficient of speed control respectively. is the airspeed change rate of the trailing aircraft;

[0070] In S41, according to the conversion relationship between the position of the leading aircraft and the route, we have:

[0071] ;

[0072] In the formula, is the projection distance of the leading aircraft relative to the take-off point of the trailing aircraft along the route direction, is the lateral distance of the leading aircraft relative to the flight path, is the altitude difference of the preceding aircraft relative to the route;

[0073] According to the conversion relationship between the leading aircraft speed and the route, we have:

[0074] ;

[0075] In the formula, , , are the forward speed, lateral speed and ground speed of the leading aircraft relative to the course;

[0076] In S42, the yaw angle command of the leading aircraft is obtained. :

[0077] ;

[0078] In the formula, is the front side offset feedback coefficient, is the speed of the front machine, is the lateral speed command of the leading machine, is the side offset instruction of the front aircraft, is the side offset of the front aircraft;

[0079] Obtain roll angle command from yaw angle command :

[0080] ;

[0081] In the formula, is the local gravitational acceleration, is the yaw angle feedback coefficient of the front aircraft side offset control, is the yaw angle of the leading aircraft;

[0082] In S43, the rear aircraft tracks the lateral offset of the front aircraft, so that the relative lateral offset between the two aircraft =0, get the yaw angle command of the rear aircraft :

[0083] ;

[0084] In the formula, is the feedback coefficient of the rear side offset, is the speed of the following aircraft;

[0085] The roll angle command of the rear aircraft is obtained from the yaw angle command:

[0086] ;

[0087] In the formula, is the yaw angle feedback coefficient of the rear aircraft side offset control, is the yaw angle of the rear aircraft.

[0088] As a preferred technical solution, step S5 includes the following steps:

[0089] S51, design the front aircraft altitude holding controller;

[0090] The input of the altitude holding controller of the front aircraft is the altitude command , the output is the lifting rate instruction :

[0091]

[0092] ;

[0093] In the formula, is the altitude instruction of the leading aircraft, is the altitude value of the preceding aircraft. is the front aircraft height, is the altitude feedback coefficient of the leading aircraft;

[0094] S52, design of the rear altitude holding controller:

[0095] The altitude command of the altitude holding controller of the rear aircraft is the altitude of the front aircraft, and the output of the altitude holding controller of the rear aircraft is the lifting rate command. :

[0096]

[0097] ;

[0098] In the formula, is the altitude command of the rear aircraft, is the rear aircraft height, is the altitude feedback coefficient of the rear aircraft.

[0099] Compared with the prior art, the present invention has the following beneficial effects:

[0100] (1) The algorithm of the present invention is simple: The method disclosed in the present invention adopts a PID control structure, which is easy for designers to master and convenient for airborne software development. It can quickly carry out design transplantation to a new configuration aircraft, with little modification to the original design and airborne software of the new configuration aircraft, thus shortening the design cycle, reducing design risks, and having high engineering application value;

[0101] (2) The present invention has less information exchange between aircraft: during formation flight, the amount of information exchange between aircraft is small. The leading aircraft only needs to send satellite positioning information, longitude and latitude, north speed, east speed and ground speed to the wingman, which has low requirements on the capacity of the communication channel between aircraft and high reliability of information exchange between aircraft.

[0102] (3) The formation system of the present invention is simple and low-cost: To realize formation flight, no additional sensors such as visual perception are required. Formation control can be achieved by using the sensors of a single aircraft, which reduces the complexity of the UAV system and the cost of onboard equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0103] Figure 1 The figure is a schematic diagram of the steps of a formation distance control method according to the present invention. DETAILED DESCRIPTION

[0104] The present invention will be further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0105] Example 1

[0106] like Figure 1 As shown, the present invention proposes a formation distance keeping method for controlling airspeed, calculates the ground speed command through the distance keeping principle, and then converts the ground speed command into the airspeed command through the proportional relationship between the airspeed and the ground speed, thereby ensuring the safety of both the UAV itself and the safety of the UAV formation.

[0107] The following steps are involved:

[0108] S1, determine the coordinate positions of the front and rear aircraft:

[0109] S11, establish the north-east coordinate system;

[0110] S12, calculating the coordinate value of the front aircraft in the north-east coordinate system;

[0111] S13, calculating the coordinate value of the rear aircraft in the north-east coordinate system;

[0112] Among them, the leading aircraft refers to the UAV located in front of the flight direction on the route, and the trailing aircraft refers to the UAV located behind the flight direction on the route.

[0113] S2, determine the relative position and relative speed relationship between the leading and trailing aircraft:

[0114] S21, calculate the flight path azimuth;

[0115] S22, calculating the position relationship between the leading aircraft and the trailing aircraft relative to the flight path;

[0116] S23, calculating the relative speed relationship between the leading machine and the trailing machine.

[0117] S3, design the formation forward distance controller:

[0118] S31, calculate the ground speed command of the rear aircraft of the formation;

[0119] S32, calculate the airspeed command of the rear aircraft;

[0120] S33, calculating the engine throttle command of the rear engine.

[0121] S4, design formation lateral distance controller:

[0122] S41, calculate the position and speed of the leading aircraft relative to the route;

[0123] S42, design the front machine lateral distance controller;

[0124] S43, design the rear engine lateral distance controller.

[0125] S5, design formation altitude holding controller:

[0126] S51, design the front aircraft altitude holding controller;

[0127] S52, design the rear machine altitude holding controller.

[0128] More specifically:

[0129] S1, determine the coordinate positions of the front and rear aircraft:

[0130] S11, first, establish the definition of the north-east coordinate system : Take the take-off point of the rear aircraft in the formation As the coordinate origin, The axis points due north. The axis points due east horizontally. The axis is perpendicular to the horizontal plane and points toward the center of the earth.

[0131] S12, obtain the coordinates of the front aircraft in the north-east coordinate system:

[0132] Through GPS navigation information, you can get the take-off point of the next aircraft Longitude ,latitude and altitude , the current position of the preceding machine ,From the conversion relationship of the latitude and longitude high coordinate system to the north-east coordinate system, we can know that:

[0133] ;

[0134] In the formula, , , are the coordinates of the front aircraft in the north-east coordinate system, is the meridian curvature radius of the take-off point of the trailing aircraft, is the radius of curvature of the y-axis circle at the take-off point of the following aircraft, both of which are related to the latitude of the take-off point of the following aircraft. related, , is the latitude of the reference point of the take-off point of the following aircraft The relevant parameters, , and are the differences between the latitude, longitude and altitude of the preceding aircraft and the reference point, namely:

[0135] ;

[0136] in,

[0137]

[0138] ;

[0139] In the formula, is the semi-major axis of the Earth ellipsoid, is the eccentricity of the Earth ellipsoid, using the WGS-84 standard, , .

[0140] S13, obtain the coordinates of the rear aircraft in the north-east coordinate system:

[0141] Similarly, the longitude of the subsequent machine can be ,latitude and altitude Get its coordinates in the north-east coordinate system.

[0142] ;

[0143] In the formula,

[0144] ;

[0145] S2, determine the relative position and relative speed relationship between the leading and trailing aircraft:

[0146] S21, calculate the flight path azimuth:

[0147] First, determine the relative position vector between the front and rear aircraft:

[0148] ;

[0149] According to the two adjacent waypoints of the route and Calculate the heading angle of the route Through the coordinate conversion relationship, it is easy to calculate the coordinates of the waypoints in the north-east coordinates. and .

[0150] have:

[0151] ;

[0152] Where atan2 is the four-quadrant inverse tangent function.

[0153] S22, calculate the relative position relationship between the leading aircraft and the trailing aircraft:

[0154] Convert the relative position vector between the leading and trailing aircraft to the flight path:

[0155] ;

[0156] in, is the relative flight path distance between the front and rear aircraft, is the relative lateral distance between the front and rear aircraft, z is the relative height between the front and rear aircraft.

[0157] S23, calculate the relative speed relationship between the leading machine and the trailing machine:

[0158] Get the speed of the preceding aircraft from the GPS navigation system The speed of the rear machine The relative speed between the two is :

[0159] ;

[0160] in, They represent the north speed, east speed and ground speed of the leading aircraft respectively. Respectively represent the north speed, east speed and ground speed of the rear aircraft, with the superscript represents the transpose operation, , , They respectively represent the northward speed difference, eastward speed difference and ground speed difference between the leading and trailing aircraft.

[0161] Convert it to the route direction :

[0162] ;

[0163] In the formula, Indicates the forward speed of the leading aircraft relative to the trailing aircraft, Indicates the lateral speed of the leading aircraft relative to the trailing aircraft. Indicates the ground speed of the leading aircraft relative to the trailing aircraft.

[0164] S3, design the forward distance keeper of the formation:

[0165] First, the forward ground speed of the leading and trailing aircraft is calculated through the northbound speed and eastbound speed of the leading and trailing aircraft, and the forward relative speed (ground speed) between the leading and trailing aircraft is obtained on this basis. Then, the ground speed controller of the trailing aircraft is designed based on the ground speed of the leading aircraft. Next, the airspeed command of the trailing aircraft is calculated through the ground speed-airspeed ratio. Finally, the throttle command of the trailing aircraft is obtained.

[0166] S31, calculate the ground speed command of the rear aircraft in the formation:

[0167] The airspeed controller of the rear aircraft is designed based on the ground speed of the front aircraft. The output is the forward ground speed command of the rear aircraft:

[0168]

[0169] ;

[0170] In the formula, is the ground speed command of the rear aircraft, is the increment of the rear engine ground speed command, is the relative forward distance feedback coefficient, , They are the proportional coefficient and integral coefficient of speed control respectively.

[0171] S32, calculate the airspeed command of the rear aircraft in the formation:

[0172] According to the current airspeed and ground speed of the trailing aircraft, the proportional relationship between the two can be obtained:

[0173] ;

[0174] In order to improve the robustness of airspeed control, Within a certain range, there are:

[0175] ;

[0176] Through ground speed conversion, the airspeed command of the following aircraft is obtained:

[0177] ;

[0178] S33, calculate the rear engine throttle command:

[0179] Obtain the engine throttle command of the rear engine through the throttle control loop :

[0180] ;

[0181] In the formula, , and They are the proportional coefficient, integral coefficient and differential coefficient of speed control respectively.

[0182] S4, design formation lateral distance controller:

[0183] S41, calculate the position and speed of the leading aircraft relative to the route:

[0184] According to the conversion relationship between the leading aircraft's position and the route, we have:

[0185] ;

[0186] In the formula, It is the projection distance of the leading aircraft relative to the take-off point of the trailing aircraft along the route direction; is the lateral distance of the leading aircraft relative to the flight path, i.e., the lateral offset distance; is the altitude difference of the preceding aircraft relative to the route.

[0187] According to the conversion relationship between the leading aircraft speed and the route, we have:

[0188] ;

[0189] In the formula, , , They are the forward speed, lateral speed and ground speed of the leading aircraft relative to the route.

[0190] S42, design of front engine lateral distance controller:

[0191] The main task of the front aircraft is to fly according to the route, so its lateral distance control coincides with the route, that is, the lateral distance instruction The input of the lateral distance controller is the lateral offset distance, and the output is the roll angle command.

[0192] First, obtain the yaw angle command of the front aircraft :

[0193] ;

[0194] In the formula, is the front side offset feedback coefficient, is the speed of the front machine.

[0195] Obtain roll angle command from yaw angle command :

[0196] ;

[0197] In the formula, is the local gravitational acceleration, is the yaw angle feedback coefficient of the front aircraft side offset control, is the yaw angle of the front aircraft.

[0198] S43, design of rear engine lateral distance controller:

[0199] The rear aircraft tracks the lateral deviation of the front aircraft Similarly, the yaw angle command of the rear aircraft can be obtained :

[0200] ;

[0201] In the formula, is the feedback coefficient of the rear side offset, The speed of the rear machine.

[0202] The roll angle command of the rear aircraft is obtained from the yaw angle command:

[0203] ;

[0204] In the formula, is the yaw angle feedback coefficient of the rear aircraft side offset control, is the yaw angle of the rear aircraft.

[0205] S5, design formation altitude holding controller:

[0206] S51, design of the front aircraft altitude holding controller:

[0207] The altitude of the preceding aircraft is in accordance with the route altitude, therefore, the altitude instruction The input of the altitude holding controller is the altitude command, and the output is the lifting rate command. :

[0208] ;

[0209] In the formula, is the altitude feedback coefficient of the leading aircraft.

[0210] S52, design of the rear altitude holding controller:

[0211] The rear aircraft tracks the altitude of the front aircraft, so the altitude command of the rear aircraft The input of the rear aircraft altitude holding controller is the front aircraft altitude, and the output is the lifting rate instruction :

[0212] ;

[0213] In the formula, is the altitude feedback coefficient of the rear aircraft.

[0214] As described above, the present invention can be preferably implemented.

[0215] All features disclosed in all embodiments in this specification, or steps in all methods or processes implicitly disclosed, except for mutually exclusive features and / or steps, can be combined and / or expanded or replaced in any manner.

[0216] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. According to the technical essence of the present invention, within the spirit and principles of the present invention, any simple modification, equivalent replacement and improvement made to the above embodiment still falls within the protection scope of the technical solution of the present invention.

Claims

1. A formation distance control method, characterized in that: When performing formation distance control, the ground speed command is calculated, and then the ground speed command is converted into the airspeed command through the proportional relationship between airspeed and ground speed; The following steps are involved: S1, determine the coordinate positions of the leading and trailing aircraft; S2, determining the relative position and relative speed relationship between the leading aircraft and the trailing aircraft; S3, design the formation forward distance controller; S4, design formation lateral distance controller; S5, design the altitude maintenance controller for the rear aircraft in the formation; The leading aircraft refers to the aircraft located ahead of the flight direction on the route, and the trailing aircraft refers to the aircraft located behind the flight direction on the route; Step S3 includes the following steps: S31, calculating the ground speed command of the rear aircraft; S32, calculate the airspeed command of the rear aircraft; S33, calculating the engine throttle command of the rear engine; Step S4 includes the following steps: S41, calculate the position and speed of the leading aircraft relative to the route; S42, design the front machine lateral distance controller; S43, design the rear engine lateral distance controller; In S31, the rear aircraft airspeed controller is designed based on the front aircraft ground speed. The output of the rear aircraft airspeed controller is the rear aircraft forward ground speed command: ； In the formula, is the ground speed command of the rear aircraft, is the increment of the rear engine ground speed command, is the relative forward distance feedback coefficient, , They are the proportional coefficient and integral coefficient of speed control respectively. is the forward distance instruction, is the relative flight path distance between the front and rear aircraft, Indicates the forward speed of the leading aircraft relative to the trailing aircraft, is the forward speed of the rear aircraft; In S32, according to the current airspeed and ground speed of the trailing aircraft, the proportional relationship between the airspeed and the ground speed is obtained, which is: ； Through ground speed conversion, the airspeed command of the following aircraft is obtained: ； In the formula, is the ratio of the airspeed of the trailing aircraft to the ground speed, is the airspeed of the rear aircraft, is the ground speed of the rear aircraft, is the airspeed instruction of the following aircraft; In S33, the throttle control circuit is used to obtain the throttle command of the engine of the rear engine. : ； In the formula, , and They are the proportional coefficient, integral coefficient and differential coefficient of speed control respectively. is the airspeed change rate of the trailing aircraft; In S41, according to the conversion relationship between the position of the leading aircraft and the route, we have: ； In the formula, is the projection distance of the leading aircraft relative to the take-off point of the trailing aircraft along the route direction, is the lateral distance of the leading aircraft relative to the flight path, is the altitude difference of the preceding aircraft relative to the route, Indicates the heading angle of the route, , , They are respectively the position of the front aircraft in the north-east coordinate system axis, axis, Axis coordinates; According to the conversion relationship between the leading aircraft speed and the route, we have: ； In the formula, , , are the forward speed, lateral speed and ground speed of the leading aircraft relative to the course; In S42, the yaw angle command of the leading aircraft is obtained. : ； In the formula, is the front side offset feedback coefficient, is the speed of the front machine, is the lateral speed command of the leading machine, is the side offset instruction of the front aircraft, is the side offset of the front aircraft; Obtain roll angle command from yaw angle command : ； In the formula, is the local gravitational acceleration, is the yaw angle feedback coefficient of the front aircraft side offset control, is the yaw angle of the leading aircraft; In S43, the rear aircraft tracks the lateral offset of the front aircraft, so that the relative lateral offset between the two aircraft =0, get the yaw angle command of the rear aircraft : ； In the formula, is the feedback coefficient of the rear side offset, is the speed of the following aircraft; The roll angle command of the rear aircraft is obtained from the yaw angle command: ； In the formula, is the yaw angle feedback coefficient of the rear aircraft side offset control, is the yaw angle of the rear aircraft.

2. A formation distance control method according to claim 1, characterized in that: Step S1 includes the following steps: S11, establish the north-east coordinate system; S12, calculating the coordinate value of the front aircraft in the north-east coordinate system; S13, calculating the coordinate value of the rear machine in the north-east coordinate system.

3. A formation distance control method according to claim 2, characterized in that: In step S11, the north-east coordinate system definition is established :Among them, the take-off point of the rear aircraft is the coordinate origin, The axis points due north. The axis points due east horizontally. The axis is perpendicular to the horizontal plane and points to the center of the earth; In step S12, the take-off point of the following aircraft is obtained through GPS navigation information. Longitude ,latitude and altitude , the current position of the front aircraft is , the conversion relationship from the longitude and latitude high coordinate system to the north-east ground coordinate system is: ； In the formula, , , They are the longitude, latitude and altitude of the preceding aircraft. is the meridian curvature radius of the take-off point of the trailing aircraft, is the radius of curvature of the yoke at the take-off point of the rear aircraft, , and They are the latitude difference, longitude difference, and altitude difference between the preceding aircraft and the reference point, namely: ； in, ； In the formula, is the semi-major axis of the Earth ellipsoid, is the eccentricity of the Earth ellipsoid; In S13, the longitude of the rear machine is ,latitude and altitude Get the coordinates of the rear aircraft in the north-east coordinate system: ； In the formula, , , They are respectively the position of the rear aircraft in the north-east coordinate system axis, axis, Axis coordinates, , and They are the latitude difference, longitude difference, and altitude difference between the rear aircraft and the reference point, namely: 。 4. A formation distance control method according to claim 3, characterized in that: Step S2 includes the following steps: S21, calculate the flight path azimuth; S22, calculating the relative position relationship between the front machine and the rear machine; S23, calculating the relative speed relationship between the leading machine and the trailing machine.

5. A formation distance control method according to claim 4, characterized in that: In step S22, the relative position vector between the front machine and the rear machine is determined: ； According to the two adjacent waypoints of the route and calculate ; The coordinates of the waypoints in the north-east coordinates are calculated through the coordinate conversion relationship. and ; have: ； In the formula, , , They are the distances between the front and rear aircraft in the north-east coordinate system. axis, axis, The relative position vector of the axis, are the longitude, latitude and altitude of waypoint A respectively, are the longitude, latitude, and altitude of waypoint B, They are respectively the waypoint A in the north-east coordinate system axis, axis, Axis coordinates, They are respectively the waypoint B in the north-east coordinate system axis, axis, Axis coordinates, atan2 is the four-quadrant inverse tangent function; In S22, the relative position vector between the leading aircraft and the trailing aircraft is converted to the flight path: ； in, is the relative flight path distance between the front and rear aircraft, is the relative lateral distance between the front and rear aircraft, is the relative height between the front and rear aircraft; In S23, the speed of the preceding aircraft is obtained from the GPS navigation system. The speed of the rear machine , the relative speed between the front and rear aircraft is : ； in, They represent the north speed, east speed and ground speed of the leading aircraft respectively. Respectively represent the north speed, east speed and ground speed of the rear aircraft. represents the transpose operation, , , Respectively represent the north speed difference, east speed difference, and ground speed difference between the leading and trailing aircraft; Convert to the route direction to get : ； In the formula, Indicates the lateral speed of the leading aircraft relative to the trailing aircraft. Indicates the ground speed of the leading aircraft relative to the trailing aircraft.

6. A formation distance control method according to claim 5, characterized in that: Step S5 includes the following steps: S51, design the front aircraft altitude holding controller; The input of the altitude holding controller of the front aircraft is the altitude command , the output is the lifting rate instruction : ； In the formula, is the altitude instruction of the leading aircraft, is the altitude value of the preceding aircraft. is the front aircraft height, is the altitude feedback coefficient of the leading aircraft; S52, design of the rear altitude holding controller: The altitude command of the altitude holding controller of the rear aircraft is the altitude of the front aircraft, and the output of the altitude holding controller of the rear aircraft is the lifting rate command. : ； In the formula, is the altitude command of the rear aircraft, is the rear aircraft height, is the altitude feedback coefficient of the rear aircraft.

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