Unmanned aerial vehicle differential take-off and landing guiding system and control method thereof

Abstract

The application relates to the technical field of unmanned planes, and discloses a differential take-off and landing guiding system of an unmanned plane and a control method thereof, which comprises the following steps: a differential reference station sends RTCM differential messages to a command control station through a UDP network; the command control station simultaneously distributes the RTCM differential messages to ground C-band, ground L-band and ground satellite communication link processing terminals according to a set link data frame format; a C-band transceiving combination, an L-band transceiving combination and a satellite communication transceiving combination receive uplink data from the ground in real time and transmit the uplink data to a flight pipe computer; the flight pipe computer monitors and processes the uplink data, and forwards differential correction information to an airborne differential satellite navigation device; and the airborne differential satellite navigation device uses the differential correction information to perform pseudorange differential and real-time dynamic carrier phase differential in real time. In this way, the differential guiding of the long-baseline redundancy of the unmanned plane can be realized, the stability of differential correction information transmission is improved, and the take-off and landing safety of the unmanned plane is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of unmanned aerial vehicles, in particular to an unmanned aerial vehicle differential take-off and landing guiding system and a control method thereof. BACKGROUND

[0002] In recent years, large and medium-sized unmanned aerial vehicles play an increasingly important role in performing special tasks due to their low cost and high efficiency, and have a broad application prospect. Compared with manned aircraft, due to the existence of link delay of more than one hundred milliseconds, pilots cannot control the unmanned aerial vehicle in real time, and the take-off and landing process of the unmanned aerial vehicle is mainly controlled autonomously by a flight computer. In order to achieve safe autonomous take-off and landing, it is necessary to rely on stable and reliable take-off and landing guiding technology.

[0003] Due to the limitations of platform carrying capacity and system cost, the existing large and medium-sized unmanned aerial vehicles usually directly adopt differential satellite positioning technology to achieve high-precision take-off and landing guiding. At present, the composition and working principle of the widely used unmanned aerial vehicle differential take-off and landing guiding system based on a data transmission radio station are as shown in Figure 1 It is composed of a ground differential satellite reference station device and an airborne differential satellite device; wherein the ground differential satellite reference station device mainly includes a ground differential satellite reference receiver, a ground satellite surveying and mapping antenna, a ground data transmission transmitting radio station, a ground radio station transmitting antenna and connecting cables between the devices; the airborne differential satellite navigation device mainly includes an airborne differential satellite receiver, an airborne satellite aviation antenna, an airborne data transmission receiving radio station, an airborne radio station receiving antenna and connecting cables between the devices. The ground differential satellite reference receiver has previously measured the accurate position of the ground satellite surveying and mapping antenna, and has observed and recorded the original data positioning information of the navigation satellite in real time, and generates differential correction information messages by calculating and processing the information of the two, and periodically sends the differential correction information messages to the ground data transmission transmitting radio station. The ground data transmission transmitting radio station and the airborne data transmission receiving radio station form a differential satellite wireless data link, and the airborne data transmission receiving radio station periodically sends the differential correction information messages output by the ground data transmission transmitting radio station to the airborne differential satellite device, so as to realize positioning.

[0004] However, the above system mainly relies on the data transmission radio station to transmit the differential correction information, and these ground data transmission transmitting radio stations and airborne data transmission receiving radio stations are basically ordinary omnidirectional radio stations. When the unmanned aerial vehicle approaches the landing field from different directions, it passively receives the differential correction information broadcasted by the ground data transmission transmitting radio station in space, and has no directional tracking capability. Due to the small power, short action distance, easy shielding and easy interference of the data transmission radio station, once facing complex electromagnetic environment (existence of interference) and geographical environment (poor visibility environment), the unmanned aerial vehicle is difficult to maintain stable tracking and differential correction information reception with the ground data transmission transmitting radio station, and the airborne differential satellite navigation device is easy to lose the differential correction information, resulting in degradation of positioning accuracy, and there is a great landing safety hazard.

[0005] Therefore, how to solve the above problems of the differential take-off and landing guidance technology based on the data transmission radio station is a technical problem to be solved by those skilled in the art. SUMMARY

[0006] Therefore, how to solve the above problems of the differential take-off and landing guidance technology based on the data transmission radio station is a technical problem to be solved by those skilled in the art.

[0007] A differential take-off and landing guidance system for unmanned aerial vehicles, comprising: a ground device and an airborne device; the ground device comprises a differential reference station, a command and control station, a ground C-band link processing terminal, a ground L-band link processing terminal and a ground satellite communication link processing terminal; the airborne device comprises a C-band transceiver combination, an L-band transceiver combination, a satellite communication transceiver combination, a flight tube computer and an airborne differential satellite navigation device; wherein,

[0008] The differential reference station is configured to send an RTCM differential message to the command and control station via a UDP network.

[0009] The command and control station is configured to distribute the obtained RTCM differential message to the ground C-band link processing terminal, the ground L-band link processing terminal and the ground satellite communication link processing terminal according to a set link data frame format.

[0010] The C-band transceiver combination, the L-band transceiver combination and the satellite communication transceiver combination are configured to receive uplink data from the ground in real time and transmit the uplink data to the flight tube computer.

[0011] The flight tube computer is configured to monitor and process the received uplink data, and forward differential correction information meeting a set condition to the airborne differential satellite navigation device.

[0012] The airborne differential satellite navigation device is configured to perform pseudorange differential and real-time kinematic carrier phase differential in real time using the differential correction information.

[0013] Preferably, in the above-mentioned differential take-off and landing guidance system for unmanned aerial vehicles provided by the embodiment of the present application, the ground C-band link processing terminal and the C-band transceiver combination, and the ground L-band link processing terminal and the L-band transceiver combination jointly form a dual-redundancy line-of-sight link; the main link of the dual-redundancy line-of-sight link is a C-link equipped with a C-directional antenna, and the backup link is an L-link equipped with an L-omnidirectional antenna.

[0014] The ground satellite communication link processing terminal and the satellite communication transceiver combination form a single-redundancy satellite communication link; the single-redundancy satellite communication link uses a Ku-band communication satellite for signal relay.

[0015] Preferably, in the unmanned aerial vehicle differential take-off and landing guiding system provided by the embodiment of the application, the differential reference station is integrated in the command control station.

[0016] The differential reference station comprises a satellite navigation antenna, a reference differential satellite navigation receiver and a UPS power supply.

[0017] Preferably, in the unmanned aerial vehicle differential take-off and landing guiding system provided by the embodiment of the application, the differential reference station is further configured to perform real-time packet processing on the complete RTCM differential message output by the reference differential satellite navigation receiver according to a data length of a set number of bytes per packet, and the part less than the set number of bytes is completed by 0; after the packet processing, differential frame serial numbers, differential frame total frame numbers and differential frame counters are added to each differential correction information frame.

[0018] Preferably, in the unmanned aerial vehicle differential take-off and landing guiding system provided by the embodiment of the application, the command control station is specifically configured to acquire the packet-processed RTCM differential message, distribute each differential data packet to the ground C-band link processing terminal, the ground L-band link processing terminal and the ground satellite communication link processing terminal after marking the differential data packet with a frame identification code.

[0019] Preferably, in the unmanned aerial vehicle differential take-off and landing guiding system provided by the embodiment of the application, the flight tube computer is specifically configured to judge whether the current differential frame counter value is equal to the previous differential frame counter value; if not, judge whether the differential frame serial number is equal to 1; if yes, set the differential correction information sending permission flag to 1, and forward the differential correction information to the airborne differential satellite navigation equipment; if not, judge whether the current differential frame counter value is continuous with the previous differential frame counter value; if continuous and the differential correction information sending permission flag is 1, forward the differential correction information to the airborne differential satellite navigation equipment; if not continuous, set the differential correction information sending permission flag to 0.

[0020] Preferably, in the unmanned aerial vehicle differential take-off and landing guiding system provided by the embodiment of the application, the C-band transceiver combination, the L-band transceiver combination and the satellite communication transceiver combination are specifically configured to transmit the uplink data to the flight tube computer through independent RS422 serial ports.

[0021] The embodiment of the application further provides a control method of the unmanned aerial vehicle differential take-off and landing guiding system provided by the embodiment of the application, comprising:

[0022] The differential reference station sends the RTCM differential message to the command control station through a UDP network.

[0023] The command control station distributes the obtained RTCM differential message to the ground C-band link processing terminal, the ground L-band link processing terminal and the ground satellite communication link processing terminal according to the set link data frame format;

[0024] The C-band transceiver combination, the L-band transceiver combination and the satellite communication transceiver combination receive the uplink data from the ground and transmit the uplink data to the flight pipe computer in real time;

[0025] The flight pipe computer monitors the state of the uplink data and monitors the integrity of the differential data packet, and forwards the differential correction information meeting the set condition to the airborne differential satellite navigation device;

[0026] The airborne differential satellite navigation device uses the differential correction information to perform pseudorange differential and real-time dynamic carrier phase differential in real time.

[0027] Preferably, in the control method of the unmanned aerial vehicle differential take-off and landing guidance system provided in the embodiment of the present application, the differential reference station sends the RTCM differential message to the command control station through the UDP network, specifically comprising:

[0028] The differential reference station performs real-time packet processing on the complete RTCM differential message output by the reference differential satellite navigation receiver according to the set data length of each packet, and the part less than the set byte number is completed with 0; after the packet processing, the differential frame sequence number, the differential frame total frame number and the differential frame counter are added to each differential correction information frame;

[0029] The differential reference station sends the packeted RTCM differential message to the command control station through the UDP network.

[0030] Preferably, in the control method of the unmanned aerial vehicle differential take-off and landing guidance system provided in the embodiment of the present application, the flight pipe computer forwards the differential correction information meeting the set condition to the airborne differential satellite navigation device, specifically comprising:

[0031] The flight pipe computer judges whether the current differential frame counter value is equal to the previous differential frame counter value;

[0032] If not, it is judged whether the differential frame sequence number is equal to 1;

[0033] If yes, the differential correction information sending permission flag is set to 1, and the differential correction information is forwarded to the airborne differential satellite navigation device; if not, it is judged whether the current differential frame counter value and the previous differential frame counter value are continuous;

[0034] If continuous and the differential correction information sending permission flag is 1, the differential correction information is forwarded to the airborne differential satellite navigation device; if not continuous, the differential correction information sending permission flag is set to 0.

[0035] From the above technical scheme can be seen, the unmanned aerial vehicle differential landing guide system provided by the application, including: ground equipment and airborne equipment;Ground equipment includes differential reference station, command and control station, ground C-band link processing terminal, ground L-band link processing terminal and ground satellite communication link processing terminal;Airborne equipment includes C-band transceiver combination, L-band transceiver combination, satellite communication transceiver combination, flight tube computer and airborne differential satellite navigation equipment;Wherein, differential reference station, for sending RTCM differential message to command and control station through UDP network;Command and control station, for distributing the obtained RTCM differential message to ground C-band link processing terminal, ground L-band link processing terminal and ground satellite communication link processing terminal according to the set link data frame format;C-band transceiver combination, L-band transceiver combination, satellite communication transceiver combination, for receiving the uplink data from the ground in real time and transmitting to flight tube computer;Flight tube computer, for monitoring and processing the received uplink data, and forwarding the differential correction information meeting the set conditions to airborne differential satellite navigation equipment;Airborne differential satellite navigation equipment, for real-time pseudorange differential and real-time dynamic carrier phase differential using differential correction information.

[0036] The above unmanned aerial vehicle differential landing guide system provided by the application can realize the redundancy long baseline differential guidance of unmanned aerial vehicle through the hardware architecture of differential reference station, command and control station, ground C-band link processing terminal, ground L-band link processing terminal, ground satellite communication link processing terminal, C-band transceiver combination, L-band transceiver combination, satellite communication transceiver combination, flight tube computer and airborne differential satellite navigation equipment, improve the stability of differential correction information transmission, ensure the landing safety of unmanned aerial vehicle, and solve the problems of small power, short action distance, easy to be blocked and easy to be interfered of data transmission radio widely used in current large and medium-sized unmanned aerial vehicle differential landing guide system.

[0037] In addition, the application also provides a corresponding control method for the unmanned aerial vehicle differential landing guide system, which further makes the above system more practical, and the method has corresponding advantages. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical scheme in the embodiments of the application or the related art, the drawings needed to be used in the embodiment or the related art description will be briefly introduced. Obviously, the drawings in the following description are only embodiments of the application, and those skilled in the art can obtain other drawings according to the provided drawings without creating labor.

[0039] Figure 1 The composition and working principle of the existing unmanned aerial vehicle differential landing guide system based on data transmission radio are shown in the figure.

[0040] Figure 2 The composition and information flow schematic diagram of the unmanned aerial vehicle differential take-off and landing guiding system provided for the embodiment of the present application are shown in the figure;

[0041] Figure 3 The differential correction information monitoring, processing and distribution logic schematic diagram of the fly tube computer provided for the embodiment of the present application is shown in the figure;

[0042] Figure 4 The fault mode conversion schematic diagram of the unmanned aerial vehicle differential take-off and landing guiding system provided for the embodiment of the present application is shown in the figure;

[0043] Figure 5 The control method flow chart of the unmanned aerial vehicle differential take-off and landing guiding system provided for the embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0044] The technical solutions in the embodiments of the present application will be clearly and completely described in combination with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0045] The present application provides a kind of unmanned aerial vehicle differential take-off and landing guiding system, as shown in Figure 2 Including: ground equipment and airborne equipment;Ground equipment includes differential reference station 1, command control station 2, ground C band link processing terminal 3, ground L band link processing terminal 4 and ground satellite communication link processing terminal 5;Airborne equipment includes C band transceiver combination 6, L band transceiver combination 7, satellite communication transceiver combination 8, fly tube computer 9 and airborne differential satellite navigation equipment;Wherein,

[0046] Differential reference station 1, for sending RTCM differential message to command control station 2 by UDP network;

[0047] Command control station 2, for distributing the RTCM differential message obtained according to the set link data frame format to ground C band link processing terminal 3, ground L band link processing terminal 4 and ground satellite communication link processing terminal 5;

[0048] C band transceiver combination 6, L band transceiver combination 7, satellite communication transceiver combination 8, for receiving uplink data from ground in real time and transmitting to fly tube computer 9;

[0049] Fly tube computer 9, for monitoring and processing the received uplink data, and forwarding the differential correction information meeting the set conditions to airborne differential satellite navigation equipment;

[0050] Airborne differential satellite navigation equipment is used to perform pseudorange differential and real-time dynamic carrier phase differential using differential correction information.

[0051] In the UAV differential take-off and landing guidance system provided in this embodiment of the invention, through the hardware architecture of differential reference station 1, command and control station 2, ground C-band link processing terminal 3, ground L-band link processing terminal 4, ground satellite communication link processing terminal 5, C-band transceiver assembly 6, L-band transceiver assembly 7, satellite communication transceiver assembly 8, flight control computer 9, and airborne differential satellite navigation equipment, redundant long baseline differential guidance for UAVs can be realized, the stability of differential correction information transmission can be improved, the safety of UAV take-off and landing can be guaranteed, and the problems of low data transmission radio power, short operating distance, susceptibility to obstruction, and susceptibility to interference that exist in the currently widely used differential take-off and landing guidance systems for large and medium-sized UAVs are well solved.

[0052] It should be noted that, in this invention, in order to increase the fault tolerance of the airborne differential satellite take-off and landing guidance system, preferably, three airborne differential satellite navigation devices can be used. Figure 2 The diagram illustrates airborne differential satellite navigation devices (01, 02, and 03) implementing triple redundancy. When only one airborne differential satellite navigation device is used, the fault tolerance is too low; device failure will directly lead to system failure. With more than three devices, increasing the number does not significantly improve system reliability, resulting in poor cost-effectiveness. When two airborne differential satellite navigation devices are used, a certain degree of fault tolerance is achieved, but the reliability is not as high as with triple redundancy. The specific number of airborne differential satellite navigation devices can be determined based on actual circumstances and is not limited here.

[0053] Furthermore, in specific implementations, in the UAV differential takeoff and landing guidance system provided in the embodiments of the present invention, the ground C-band link processing terminal 3 and the C-band transceiver assembly 6, and the ground L-band link processing terminal 4 and the L-band transceiver assembly 7 together constitute a dual-redundant line-of-sight link; the main link of the dual-redundant line-of-sight link is a C-link equipped with a C-directional antenna, and the backup link is an L-link equipped with an L-omnidirectional antenna; the ground satellite communication link processing terminal 5 and the satellite communication transceiver assembly 8 constitute a single-redundant satellite communication link; the single-redundant satellite communication link uses Ku-band communication satellites for signal relay. In this way, the dual-redundant line-of-sight link and the single-redundant satellite communication link can improve the takeoff and landing safety of UAVs in complex electromagnetic environments (with interference) and geographical environments (poor line-of-sight).

[0054] It should be noted that the link system is an important part of the unmanned aerial vehicle system, has the functions of remote control, telemetry, tracking and positioning and information transmission, and has the ability of simultaneously transmitting load information. The composite link proposed by the application is composed of a dual-redundancy (C band + L band) line-of-sight link + a single-redundancy (Ku band) satellite communication link, and the reliability, transmission stability and anti-interference ability of the entire link system are improved through three-redundancy configuration. The C link is the main link of the system, is equipped with a C directional antenna, has directional stable tracking ability, and has an action distance of 300 km. The L link is a backup of the C link, is equipped with an L omnidirectional antenna, has omnidirectional tracking ability, can overcome the influence of most terrain (mountain peaks, buildings) under the condition of not being completely blocked, and has an action distance of 300 km. The satellite communication link uses a Ku frequency band communication satellite to relay signals, is equipped with a Ku directional antenna, has directional stable tracking ability, realizes information transmission between the unmanned aerial vehicle and the ground station in the beyond line-of-sight range, and has an action distance of greater than or equal to 300 km. In addition, the line-of-sight / satellite communication link adopts various technologies such as spread spectrum, frequency hopping and data encryption to improve the anti-interference and anti-hijacking ability. Therefore, compared with an ordinary data transmission radio station, the composite link of the application has various advantages such as long transmission distance, high reliability, difficulty in cracking, strong anti-interference ability, directional / omnidirectional dual-mode tracking, and the like, and can ensure the stability and reliability of the differential correction information transmission of the unmanned aerial vehicle (especially a medium / large unmanned aerial vehicle).

[0055] Specifically, as shown in Figure 2 The differential reference station 1 sends the RTCM differential message to the network switch of the command control station 2 through the UDP network, the command control station 2 instructs the encoding software to periodically access the differential message port, the obtained RTCM differential message is simultaneously distributed to the ground C band link processing terminal 3, the ground L band link processing terminal 4 and the ground satellite communication link processing terminal 5 according to the set link data frame format, and finally transmitted to the unmanned aerial vehicle through the C / L / satellite communication three independent links. At the unmanned aerial vehicle end, the C band transceiver combination 6, the L band transceiver combination 7 and the satellite communication transceiver combination 8 receive the uplink data from the ground in real time, and transmit the uplink data to the flight computer 9 through independent RS422 serial ports. The flight computer 9 monitors the state of the C / L / satellite communication uplink data, and monitors the integrity of the differential data packet, and simultaneously forwards the differential message meeting the conditions to the airborne differential satellite navigation devices 01, 02 and 03. The airborne differential satellite navigation devices 01, 02 and 03 utilize the differential correction information in real time to perform pseudo-range difference and real-time dynamic carrier phase difference (RTK), weaken the orbit error, clock error, ephemeris error, ionospheric error and tropospheric delay error existing in satellite positioning, and thus realize high-precision positioning.

[0056] In the specific implementation, in the above unmanned aerial vehicle differential take-off and landing guidance system provided by the embodiment of the application, as Figure 2As shown, the C-band transceiver combination 6, the L-band transceiver combination 7, and the satellite transceiver combination 8 are specifically used for transmitting uplink data to the flight pipe computer 9 through independent RS422 serial ports.

[0057] In the specific implementation, in the unmanned aerial vehicle differential take-off and landing guiding system provided by the embodiment of the present application, the ground can be configured with a differential reference station 1, and the differential reference station 1 is integrated in the command control station 2. The differential reference station 1 can include a satellite navigation antenna, a reference differential satellite navigation receiver and a UPS power supply, and has functions of satellite navigation signal receiving, reference point calibration, differential correction information calculation, differential correction information broadcasting and closed loop detection. The differential correction information adopts an RTCM V3 message format, the message content is RTCM 1006 (reference point coordinate information), RTCM 1074 (GPS original observation) and RTCM 1124 (BDS original observation), and the message content supports an autonomous configuration function.

[0058] In the specific implementation, in the unmanned aerial vehicle differential take-off and landing guiding system provided by the embodiment of the present application, the differential reference station 1 can also be used for performing real-time packet processing on the complete RTCM differential message output by the reference differential satellite navigation receiver according to the data length of the set number of bytes per packet, and the part less than the set number of bytes is completed by 0; after the packet processing, the differential frame serial number, the differential frame total frame number and the differential frame counter are added to each differential correction information frame. Further, the command control station 2 can be specifically used for obtaining the packet-processed RTCM differential message, distributing each differential data packet to the ground C-band link processing terminal 3, the ground L-band link processing terminal 4 and the ground satellite link processing terminal 5 after marking the frame identification code.

[0059] It should be noted that the present application realizes the uplink transmission of differential correction data through the unmanned aerial vehicle control link, and maintains the reliability of the entire link through the non-similar redundancy configuration of the directional + omnidirectional, line-of-sight + satellite. However, due to the limitation of the transmission capacity of the unmanned aerial vehicle link, the length of the differential correction data that can be additionally transmitted each time is defined as 53 bytes without affecting the normal uplink remote control data transmission, as shown in Table 1.

[0060] Table 1 Differential correction information frame definition

[0061]

[0062] For the RTCM 1074 and RTCM 1124 messages of the GPS system and the BDS system, the more the satellite search number of the reference differential satellite navigation receiver, the longer the message length, which can reach 100 or even 200 bytes or more. Therefore, the differential reference station 1 needs to perform real-time packet processing on the complete RTCM differential message output by the embedded reference differential satellite navigation receiver to meet the link transmission requirements.

[0063] The specific packet logic can be packet processing of the complete RTCM differential message according to the data length of every 50 bytes, and the part less than 50 bytes is completed by 0. After the complete RTCM differential message is packeted, two bytes of additional information are added to each differential correction information frame, so as to monitor the state of each differential data frame in the transmission process. The definition of the additional information is as follows:

[0064] Additional information 1 (uint8):

[0065] The low four bits represent the differential frame number, that is, the current frame is the frame number of the complete RTCM message, for example, 1;

[0066] The high four bits represent the total number of differential frames, that is, the total frame number of the complete RTCM message, for example, 4;

[0067] For example, an RTCM message with a length of 180 bytes is divided into four packets, and the additional information is as follows: 0x41, 0x42, 0x43, 0x44.

[0068] Additional information 2: frame counter, 0-255 cycle;

[0069] The differential reference station 1 transmits the packeted RTCM differential message to the command control station 2 network switch in turn, and the instruction coding software distributes the differential data packet to the C / L / satellite ground link terminal in turn after marking the frame identification code (0x76) on each differential data packet, and transmits the differential data packet to the unmanned aerial vehicle end through the C / L / satellite link.

[0070] The design of the reasonable and feasible differential message packet logic can well solve the influence of the large amount of RTCM differential message data on the link transmission.

[0071] In the specific implementation, in the unmanned aerial vehicle differential take-off and landing guidance system provided by the embodiment of the application, the flight tube computer 9 can be specifically used to judge whether the current differential frame counter value is equal to the previous differential frame counter value; if not, judge whether the differential frame number is equal to 1; if yes, set the differential correction information sending permission flag to 1, and forward the differential correction information to the airborne differential satellite navigation device; if not, judge whether the current differential frame counter value is continuous with the previous differential frame counter value; if continuous and the differential correction information sending permission flag is 1, forward the differential correction information to the airborne differential satellite navigation device; if not continuous, set the differential correction information sending permission flag to 0.

[0072] Specifically, the UAV terminal monitors, manages, and distributes the differential correction data uplinked from the ground link through the flight control computer 9. This overcomes the impact of a single point of failure that would otherwise occur when the differential correction information is transmitted directly to the airborne differential satellite navigation equipment via the airborne data transmission differential radio. It also prevents a single data transmission link failure from causing a differential satellite navigation equipment to degrade to a single-point positioning state, thus maintaining the robustness of the differential positioning state of the entire system.

[0073] like Figure 3 As shown, the specific implementation of the differential correction information monitoring, processing, and distribution logic of the flight control computer is as follows:

[0074] The link data is selected from the three powered-on links according to the following processing logic: The link with directional tracking capability is used first, in the order of C / Satellite Communication / L. If any link has no serial communication failure, its data is selected as the "valid link serial port voting data," and the link serial port data source is recorded. "Valid link serial port voting data" can be understood as follows: The link system consists of three mutually redundant physical links (C / L / Satellite Communication). Their onboard terminals send the same data to the aircraft management computer through independent serial ports. At any given time, the aircraft management computer only needs to select one usable link data from the three link serial port data according to the voting rules as the valid link serial port voting data for use by the relevant software logic.

[0075] If the frame identification code of "link serial port voting valid data" is 0x76 (differential data frame), then proceed with the subsequent logic; otherwise, exit.

[0076] Determine the following states in the "Link Serial Port Voting Valid Data": differential frame sequence number, total number of frames, and differential frame counter:

[0077] If the current differential frame counter value is not equal to the previous differential frame counter value, the subsequent logic proceeds; otherwise, the process exits. In practical applications, the previous differential frame counter value is initialized to 0.

[0078] If the differential frame sequence number is equal to 1, then according to the communication protocol format from VMC to airborne differential satellite navigation equipment 1 / 2 / 3, the differential correction data of the set number of bytes (e.g., 50 bytes) in "Link Serial Port Voting Valid Data" will be simultaneously filled into "VMC Output to Airborne Differential Satellite Navigation Equipment 01 Serial Port Data", "VMC Output to Airborne Differential Satellite Navigation Equipment 02 Serial Port Data", and "VMC Output to Airborne Differential Satellite Navigation Equipment 03 Serial Port Data", and the "Link Differential Data Transmission Allow Flag" will be set to 1 (1 indicates that transmission is allowed, initialized to 1). Here, the "Link Differential Data Transmission Allow Flag" refers to a custom status word defined in the software design, used to determine whether to forward differential data to the airborne differential satellite navigation equipment.

[0079] If the difference frame serial number is not equal to 1, the current difference frame counter value and the previous beat difference frame counter value are compared. If continuous and the ''link difference data transmission permission flag word'' is equal to 1, the ''link serial port voting effective data'' is filled into ''VMC output to airborne differential satellite navigation equipment 01 serial port data'', ''VMC output to airborne differential satellite navigation equipment 02 serial port data'', ''VMC output to airborne differential satellite navigation equipment 03 serial port data'' according to the communication protocol format of VMC to airborne differential satellite navigation equipment 01 / 02 / 03, with a set number of bytes (such as 50 bytes) of difference correction data; if continuous but the ''link difference data transmission permission flag word'' is not equal to 1, exit. If not continuous, the ''link difference data transmission permission flag word'' is set to 0 (0 indicates that transmission is prohibited), and exit.

[0080] If the flight tube computer 9 is restarted after power failure in the air, the ''link difference data transmission permission flag word'' is still initialized to 1, and the previous beat difference frame counter value is still initialized to 0.

[0081] In the present application, as shown in FIG. 1, the differential correction data on the ground link uplink is monitored, managed and distributed by the flight tube computer 9 at the unmanned aerial vehicle end, realizing three-redundancy configuration of differential guidance. Figure 4 Under normal circumstances, the differential correction data on the C-link uplink is preferentially used, and the differential correction data on the L-link and the satellite communication link uplink are in a hot backup state. As long as one link is effective, the airborne differential satellite navigation equipment 01 / 02 / 03 can receive effective differential correction data, which can significantly improve the redundancy level of the differential guidance system, avoid the degradation of the redundancy of the entire unmanned aerial vehicle differential guidance system caused by a single fault, significantly improve the fault tolerance capability, and provide a guarantee for the safety of the unmanned aerial vehicle during the take-off and landing stage.

[0082] Based on the same inventive concept, the present application also provides a control method of the unmanned aerial vehicle differential take-off and landing guidance system. Since the principle of solving the problem of the method is similar to that of the aforementioned unmanned aerial vehicle differential take-off and landing guidance system, the implementation of the method can be referred to the implementation of the unmanned aerial vehicle differential take-off and landing guidance system, and the repeated parts will not be described herein.

[0083] In the specific implementation, the control method of the unmanned aerial vehicle differential take-off and landing guidance system provided by the present application embodiment, as shown in FIG. 1, specifically includes the following steps: Figure 5

[0084] S501, the differential reference station sends the RTCM differential message to the command control station through the UDP network;

[0085] S502, the command control station distributes the obtained RTCM differential message to the ground C-band link processing terminal, the ground L-band link processing terminal and the ground satellite communication link processing terminal according to the set link data frame format; ​

[0086] S503, the C-band transceiver combination, the L-band transceiver combination, and the satellite transceiver combination receive uplink data from the ground in real time and transmit to the flight pipe computer;

[0087] S504, the flight pipe computer performs state monitoring on the uplink data, monitors the integrity of the differential data packet, and forwards the differential correction information meeting the set condition to the airborne differential satellite navigation device;

[0088] S505, the airborne differential satellite navigation device performs pseudorange differential and real-time dynamic carrier phase differential in real time using the differential correction information.

[0089] In the control method of the unmanned aerial vehicle differential take-off and landing guidance system provided in the embodiment of the application, the redundancy long baseline differential guidance of the unmanned aerial vehicle can be realized, the stability of differential correction information transmission is improved, the safety of unmanned aerial vehicle take-off and landing is ensured, and the problems of small power, short action distance, easy to be blocked and easy to be interfered of the data transmission radio widely used in the differential take-off and landing guidance system of large and medium-sized unmanned aerial vehicles are well solved.

[0090] In specific implementation, in the control method of the unmanned aerial vehicle differential take-off and landing guidance system provided in the embodiment of the application, the step S501 that the differential reference station sends the RTCM differential message to the command control station through the UDP network can specifically include the following steps: first, the differential reference station performs real-time packet processing on the complete RTCM differential message output by the reference differential satellite navigation receiver according to the data length of each packet set byte number, and the part less than the set byte number is completed with 0; after the packet processing, differential frame sequence numbers, differential frame total frame numbers and differential frame counters are added to each differential correction information frame; then, the differential reference station sends the packeted RTCM differential message to the command control station through the UDP network.

[0091] In specific implementation, in the control method of the unmanned aerial vehicle differential take-off and landing guidance system provided in the embodiment of the application, the step S504 that the flight pipe computer forwards the differential correction information meeting the set condition to the airborne differential satellite navigation device can specifically include the following steps: the flight pipe computer judges whether the current differential frame counter value is equal to the previous differential frame counter value; if not, it is judged whether the differential frame sequence number is equal to 1; if yes, the differential correction information sending permission flag is set to 1, and the differential correction information is forwarded to the airborne differential satellite navigation device; if not, it is judged whether the current differential frame counter value is continuous with the previous differential frame counter value; if continuous and the differential correction information sending permission flag is 1, the differential correction information is forwarded to the airborne differential satellite navigation device; if not continuous, the differential correction information sending permission flag is set to 0.

[0092] The detailed working process of each step can refer to the corresponding content disclosed in the foregoing embodiments, and will not be described here again.

[0093] Each embodiment in the specification is described in a progressive manner, and each embodiment focuses on the difference from other embodiments. The same or similar parts between each embodiment can be referred to each other. For the control method disclosed in the embodiments, since it corresponds to the system disclosed in the embodiments, the description is relatively simple, and the relevant part can refer to the system part.

[0094] The skilled person can further realize that the units and algorithm steps of each example described in combination with the embodiments disclosed in the specification can be realized by electronic hardware, computer software or a combination of both. In order to clearly show the interchangeability of hardware and software, the components and steps of each example have been described in the foregoing description. Whether the functions are realized by hardware or software depends on the specific application and design constraints of the technical solution. The skilled person can use different methods to realize the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0095] The steps of the method or algorithm described in combination with the embodiments disclosed in the specification can be directly implemented by hardware, a software module executed by a processor, or a combination of both. The software module can be placed in a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

[0096] In summary, the unmanned aerial vehicle differential take-off and landing guiding system and the control method thereof provided by the embodiment of the application comprise: a ground device and an airborne device; the ground device comprises a differential reference station, a command control station, a ground C-band link processing terminal, a ground L-band link processing terminal and a ground satellite communication link processing terminal; the airborne device comprises a C-band transceiving combination, an L-band transceiving combination, a satellite communication transceiving combination, a flight computer and an airborne differential satellite navigation device; wherein the differential reference station is configured to send RTCM differential messages to the command control station through a UDP network; the command control station is configured to simultaneously distribute the obtained RTCM differential messages to the ground C-band link processing terminal, the ground L-band link processing terminal and the ground satellite communication link processing terminal according to a set link data frame format; the C-band transceiving combination, the L-band transceiving combination and the satellite communication transceiving combination are configured to receive uplink data from the ground in real time and transmit the uplink data to the flight computer; the flight computer is configured to monitor and process the received uplink data and forward differential correction information meeting a set condition to the airborne differential satellite navigation device; and the airborne differential satellite navigation device is configured to perform pseudorange differential and real-time dynamic carrier phase differential by using the differential correction information in real time. The unmanned aerial vehicle differential take-off and landing guiding system can realize multi-redundancy long baseline differential guidance of the unmanned aerial vehicle, improve the stability of differential correction information transmission, ensure the take-off and landing safety of the unmanned aerial vehicle and solve the problems of small power, short action distance, easy to be blocked and easy to be interfered of the data transmission radio widely used in the differential take-off and landing guiding system of large and medium-sized unmanned aerial vehicles. In addition, the application also provides a corresponding control method for the unmanned aerial vehicle differential take-off and landing guiding system, which further makes the system more practical, and the method has corresponding advantages.

[0097] Finally, it should be noted that, in this document, the terms such as first and second are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between such entities or operations. Moreover, the terms "comprises", "comprising", or any other variations thereof are intended to cover non-exclusive inclusions, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed or inherent to such a process, method, article or device. Without more limitations, the element defined by the statement "comprises a" does not exclude the presence of additional identical elements in the process, method, article or device including the element.

[0098] The unmanned aerial vehicle differential take-off and landing guiding system and the control method thereof are described in detail above, the principle and the implementation mode of the present application are described by applying specific examples in this paper, the above example is only used to help understand the method of the present application and its core idea; at the same time, for the general technical personnel in the art, according to the idea of the present application, the specific implementation mode and the application range will be changed, and the above description should not be understood as the limitation of the present application.

Claims

1. A differential takeoff and landing guidance system for unmanned aerial vehicles (UAVs), characterized in that, include: Ground equipment and airborne equipment; the ground equipment includes a differential reference station, a command and control station, a ground C-band link processing terminal, a ground L-band link processing terminal, and a ground satellite communication link processing terminal; the airborne equipment includes a C-band transceiver unit, an L-band transceiver unit, a satellite communication transceiver unit, a flight control computer, and airborne differential satellite navigation equipment; wherein... The differential reference station is used to send RTCM differential messages to the command and control station via a UDP network; The command and control station is used to distribute the acquired RTCM differential messages to the ground C-band link processing terminal, the ground L-band link processing terminal and the ground satellite communication link processing terminal according to the set link data frame format. The C-band transceiver combination, the L-band transceiver combination, and the satellite communication transceiver combination are used to receive uplink data from the ground in real time and transmit it to the flight control computer. The flight control computer is used to monitor and process the received uplink data, and forward differential correction information that meets the set conditions to the airborne differential satellite navigation equipment. The airborne differential satellite navigation equipment is used to perform pseudorange differential and real-time dynamic carrier phase differential using the differential correction information.

2. The UAV differential takeoff and landing guidance system according to claim 1, characterized in that, The ground C-band link processing terminal and the C-band transceiver assembly, together with the ground L-band link processing terminal and the L-band transceiver assembly, constitute a dual-redundant line-of-sight link; the main link of the dual-redundant line-of-sight link is a C-link equipped with a C-directional antenna, and the backup link is an L-link equipped with an L-omnidirectional antenna; The ground satellite communication link processing terminal and the satellite communication transceiver unit constitute a single-redundant satellite communication link; the single-redundant satellite communication link uses Ku-band communication satellites for signal relay.

3. The UAV differential takeoff and landing guidance system according to claim 1, characterized in that, The differential reference station is integrated into the command and control station; The differential reference station includes a satellite navigation antenna, a reference differential satellite navigation receiver, and a UPS power supply.

4. The UAV differential takeoff and landing guidance system according to claim 3, characterized in that, The differential reference station is also used to perform real-time packet processing on the complete RTCM differential message output by the reference differential satellite navigation receiver according to the data length of the set number of bytes per packet, and pad the part that is less than the set number of bytes with 0; after packet processing, add differential frame sequence number, total number of differential frames and differential frame counter to each differential correction information frame.

5. The UAV differential takeoff and landing guidance system according to claim 4, characterized in that, The command and control station is specifically used to acquire the packetized RTCM differential messages, add a frame identification code to each differential data packet, and distribute it to the ground C-band link processing terminal, the ground L-band link processing terminal, and the ground satellite communication link processing terminal.

6. The UAV differential takeoff and landing guidance system according to claim 5, characterized in that, The flight control computer is specifically used to determine whether the current differential frame counter value is equal to the previous differential frame counter value; if they are not equal, it determines whether the differential frame sequence number is equal to 1; if so, it sets the differential correction information transmission permission flag to 1 and forwards the differential correction information to the airborne differential satellite navigation equipment; if not, it determines whether the current differential frame counter value is continuous with the previous differential frame counter value. If the differential correction information transmission enable flag is 1, the differential correction information is forwarded to the airborne differential satellite navigation device; if it is not continuous, the differential correction information transmission enable flag is set to 0.

7. The UAV differential takeoff and landing guidance system according to claim 6, characterized in that, The C-band transceiver combination, the L-band transceiver combination, and the satellite communication transceiver combination are specifically used to transmit the uplink data to the flight control computer through an independent RS422 serial port.

8. A control method for a UAV differential takeoff and landing guidance system as described in any one of claims 1 to 7, characterized in that, include: The differential reference station sends RTCM differential messages to the command and control station via the UDP network; The command and control station distributes the acquired RTCM differential messages to the ground C-band link processing terminal, the ground L-band link processing terminal, and the ground satellite communication link processing terminal according to the set link data frame format. The C-band transceiver unit, L-band transceiver unit, and satellite communication transceiver unit receive uplink data from the ground in real time and transmit it to the flight control computer. The flight control computer monitors the status of the uplink data and the integrity of the differential data packets, and forwards differential correction information that meets the set conditions to the airborne differential satellite navigation equipment. The airborne differential satellite navigation equipment uses the differential correction information in real time to perform pseudorange differential and real-time dynamic carrier phase differential.

9. The control method for the UAV differential takeoff and landing guidance system according to claim 8, characterized in that, The differential base station sends RTCM differential messages to the command and control station via the UDP network, specifically including: The differential reference station performs real-time packet processing on the complete RTCM differential message output by the reference differential satellite navigation receiver according to the data length of the set number of bytes per packet. Parts that are less than the set number of bytes are padded with 0. After packet processing, a differential frame sequence number, a total number of differential frames, and a differential frame counter are added to each differential correction information frame. The differential base station sends the packetized RTCM differential messages to the command and control station via the UDP network.

10. The control method for the UAV differential takeoff and landing guidance system according to claim 9, characterized in that, The flight control computer forwards differential correction information that meets the set conditions to the airborne differential satellite navigation equipment, specifically including: The flight control computer determines whether the current differential frame counter value is equal to the previous differential frame counter value; If they are not equal, then check if the differential frame number is equal to 1; If yes, then set the differential correction information transmission enable flag to 1 and forward the differential correction information to the airborne differential satellite navigation device; if no, then determine whether the current differential frame counter value is continuous with the previous differential frame counter value. If the differential correction information transmission enable flag is 1, the differential correction information is forwarded to the airborne differential satellite navigation device; if it is not continuous, the differential correction information transmission enable flag is set to 0.

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