Unmanned aerial vehicle accurate landing navigation system

Abstract

The invention provides an unmanned aerial vehicle accurate landing navigation system which comprises a mobile station GPS and a base station GPS, longitude and latitude data of the base station GPS are sent to the mobile station GPS in a wireless communication mode, position difference is carried out through the longitude and latitude of the base station GPS and the longitude and latitude of the mobile station GPS, and the distance between the mobile station and the base station is calculated. The method has the beneficial effects that the landing navigation precision is high, and the problem that the landing point is difficult to find when the unmanned aerial vehicle lands in the field is well solved. The price is low, the cost performance is high, and the commercial value is high.

Description

Technical Field

[0001] The present invention relates to the technical field of unmanned aerial vehicles, and in particular to a precise landing navigation system for unmanned aerial vehicles. Background Art

[0002] In recent years, drones have demonstrated their application advantages in many fields, such as aerial photography, surveying and mapping, agricultural plant protection, and line inspection, so drones have also been widely used in these fields. After completing the assigned mission, drones need to land and be recovered. However, the landing site is often in a field environment with complex terrain. In order to safely recover the drone, a reliable positioning system is required to navigate the drone to the landing point. The current mainstream drone landing navigation solutions are as follows:

[0003] 1. Use GPS navigation to land. Use the GPS on the drone to navigate the drone to the landing point. The landing accuracy depends entirely on the GPS positioning accuracy. The GPS positioning accuracy can generally reach 5m, and the error increases to about 10m in cloudy weather. Therefore, a flat area with a radius of 10m should be found as the landing point to ensure the safe landing of the drone. However, it is not easy to find a landing area with a radius of 10m in the wild.

[0004] 2. Use Real-time kinematic positioning technology. This solution is a real-time dynamic positioning technology based on carrier phase observations. It can provide real-time three-dimensional positioning results of the measuring station in the specified coordinate system, with positioning accuracy at the centimeter level. RTK can be used to accurately navigate to the landing point, and only a small area is required as the landing point, which is easy to find in the wild. However, this solution requires the establishment of a base station, which is more troublesome to use. At the same time, the cost of RTK is very high, generally more than 10,000 yuan. If the drone does not require centimeter-level positioning accuracy when working, and RTK is only installed for precise landing, the cost of the drone will increase significantly, and the cost performance is low.

[0005] In summary, the above landing scheme 1 has low cost and is easy to implement, but has low landing accuracy. Scheme 2 has high landing accuracy, but is high in cost and inconvenient to use. Summary of the invention

[0006] In order to solve the problems in the prior art, the present invention provides a UAV precise landing navigation system, which has the advantages of high accuracy and low price and can better solve the problem of UAV landing in the wild.

[0007] The invention provides a precise landing navigation system for unmanned aerial vehicles, comprising a mobile station GPS and a base station GPS. The latitude and longitude data of the base station GPS are sent to the mobile station GPS by wireless communication. The latitude and longitude of the base station GPS and the mobile station GPS are used to perform position difference, and the distance between the mobile station and the base station is calculated.

[0008] As a further improvement of the present invention, when in use, the mobile station is placed on the UAV, and the base station is placed at the landing point. The base station GPS longitude and latitude data are sent to the mobile station GPS of the UAV by wireless communication. The longitude and latitude of the base station GPS and the mobile station GPS are used to perform position differentiation to calculate the distance between the UAV and the landing point.

[0009] As a further improvement of the present invention, the GPS longitude and latitude (Lat1, Lng1) of the base station is transmitted to the UAV in real time by wireless means. The UAV obtains its own longitude and latitude (Lat2, Lng2) through the onboard mobile station GPS. The longitude difference between the UAV and the landing point is calculated to be ΔLng, and the latitude difference is ΔLat. The longitude difference and the latitude difference represent the horizontal distance between the UAV and the landing point. The UAV is navigated to the landing point using the horizontal distance.

[0010] As a further improvement of the present invention, the base station includes a ground radio station, a signal superimposer and a base station GPS, the mobile station includes an aerial radio station and a mobile station GPS, the base station sends the longitude and latitude of its own GPS to the signal superimposer, and while the signal superimposer completes the data transmission between the ground station and the ground radio station, it superimposes the longitude and latitude on the data stream and sends it to the aerial radio station. After the drone obtains the longitude and latitude of the base station, it uses the mobile station GPS data to achieve position differential positioning.

[0011] As a further improvement of the present invention, the base station GPS includes a GPS, a wireless serial port and a battery, the battery is connected to the GPS and the wireless serial port respectively, the GPS and the wireless serial port are connected, the battery supplies power to the GPS and the wireless serial port, and the wireless serial port transmits the GPS data to the signal superimposer through an antenna.

[0012] As a further improvement of the present invention, the base station GPS further includes a switch, one end of the switch is connected to the battery, and the other end of the switch is respectively connected to the GPS and the wireless serial port.

[0013] As a further improvement of the present invention, the battery is a lithium battery, and the GPS communicates with the wireless serial port through TX and RX ports.

[0014] As a further improvement of the present invention, the signal superimposer includes a single-chip microcomputer and a wireless serial port. The single-chip microcomputer is connected to the wireless serial port and the ground station respectively. The wireless serial port data and the ground station data are simultaneously connected to the single-chip microcomputer, and after superposition, they communicate with the ground station to complete the transmission of two data channels.

[0015] As a further improvement of the present invention, the single chip microcomputer is STM32L051, STM32L051 has three serial ports UART1-3, the pins of UART1 are PA9 and PA10, PA9 and PA10 are connected to the ground station; the pins of UART2 are PA2 and PA3, PA2 and PA3 are connected to the wireless serial port; the pins of UART3 are PB6 and PB7, which are connected to the ground radio station.

[0016] As a further improvement of the present invention, the signal superimposer also includes capacitor C1 and capacitor C2, capacitor C1 is a reset capacitor, capacitor C1 is connected to the reset terminal NRST of the microcontroller; capacitor C2 is a filter capacitor, capacitor C2 is connected in parallel across the 3.3V voltage; the signal superimposer is connected to an external 3.3V power supply.

[0017] The beneficial effects of the present invention are: the landing navigation accuracy is high, and the problem of difficulty in finding a landing point for a UAV to land in the wild is solved well. The price is low, the cost performance is high, and the commercial value is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the landing navigation scheme of the UAV of the present invention;

[0019] Figure 2 It is a schematic diagram of the traditional UAV communication system;

[0020] Figure 3 It is a schematic diagram of a position differential positioning system;

[0021] Figure 4 This is the GPS hardware structure diagram of the base station;

[0022] Figure 5 It is the GPS circuit diagram of the base station;

[0023] Figure 6 This is the hardware structure diagram of the signal adder;

[0024] Figure 7 This is the signal adder circuit diagram. DETAILED DESCRIPTION

[0025] The method of the present invention for solving the problem of accurate landing of UAV mainly uses a technology called position difference, and designs a solution for applying the position difference technology to the landing of UAV.

[0026] 1. Overall landing plan

[0027] 1. Position differential technology

[0028] Position differential technology is mainly used to improve GPS positioning accuracy. According to the different sources of GPS errors, these errors are divided into three parts: satellite-related errors (such as satellite clock errors, etc.), signal propagation-related errors (such as tropospheric delay errors, etc.), and receiver-related errors (such as multipath effects, etc.) [1].

[0029] Differential technology can effectively eliminate the above-mentioned satellite-related errors and most of the errors related to signal propagation, but it cannot eliminate the errors related to the receiver[2].

[0030] Differential technology is divided into four types: position differential, pseudorange differential, phase smoothed pseudorange differential and carrier phase differential. Among them, position differential has the characteristics of simple calculation method, small transmission differential correction number and good compatibility [3]. Within a certain distance, since the path experienced by GPS satellite signals when transmitted to the mobile station GPS and the base station GPS is basically the same, it is less affected by atmospheric refraction and multipath effects, and can achieve positioning of about 1.5m-2m, proving that position differential has a significant improvement in improving positioning accuracy [4].

[0031] When using the position difference method, two GPS are required, one is called the base station GPS. Its position is generally fixed during operation, and its horizontal coordinates are marked as (Lat1, Lng1). Lat is the abbreviation of Latitude, and Lng is the abbreviation of Longitude. Although GPS also provides altitude information, it is ignored due to its large error. The other is called the mobile station GPS, and its position can be moved during operation. The horizontal coordinates are marked as (Lat2, Lng2). The so-called position difference technology is used to measure the difference in longitude and latitude between the mobile station and the base station, and then use the difference in longitude and latitude for navigation. Let ΔLat be the latitude difference, and ΔLng be the longitude difference, then:

[0032] ΔLat=Lat2-Lat1#(1)

[0033] ΔLng=Lng2-Lng1#(2)

[0034] ΔLat and ΔLng represent the difference in longitude and latitude between the mobile station and the base station. The distance difference can be converted using a formula, and the distance difference is the required navigation data.

[0035] 2. Landing Navigation Plan

[0036] When the position difference technology is applied to the navigation of the UAV during the landing phase, the mobile station GPS is placed on the UAV, and the base station GPS is placed at the landing point. The base station GPS longitude and latitude data are sent to the UAV using wireless communication. The longitude and latitude of the base station GPS and the mobile station GPS are used to seal the location and calculate the distance between the UAV and the landing point.

[0037] The navigation scenario of the drone during landing is as follows: Figure 1 As shown in the figure, the UAV is flying in the air. After projecting its position onto the same horizontal plane as the landing point, the longitude difference between the UAV and the landing point is ΔLng, and the latitude difference is ΔLat. A base station GPS (GPS1) is placed in the landing area, and the UAV is equipped with a mobile station GPS (GPS2) for flight. The longitude and latitude of the base station GPS (Lat1, Lngl) are transmitted to the UAV in real time by wireless means. The UAV obtains its own longitude and latitude (Lat2, Lng2) through the onboard mobile station GPS2, and the longitude and latitude difference (ΔLat, ΔLng) is obtained by calculation. The longitude and latitude difference also represents the horizontal distance between the UAV and the landing point. Using the horizontal distance, the UAV can be navigated to the landing point, achieving a landing error of less than 2m.

[0038] 2. Structural plan

[0039] In order to apply differential positioning to UAV systems, a landing navigation system based on the traditional UAV communication system is designed. First, the communication system of the traditional UAV is introduced, such as Figure 2 As shown. Traditional UAV communication systems generally consist of three parts: ground station, ground radio, and aerial radio. Ground station is the abbreviation of ground control station, which is used to control the flight of UAV. The ground radio and aerial radio form a ground-to-air communication link, sending the control commands of the ground station to the UAV, and sending the UAV status to the ground station for display.

[0040] Based on the traditional UAV communication system, the structure after adding the position differential positioning function is as follows Figure 3 As shown in the figure, compared with the original structure, a base station GPS and a signal superimposer are mainly added. The base station GPS sends the GPS longitude and latitude to the signal superimposer. While the signal superimposer completes the data transmission between the ground station and the ground radio station, it superimposes the longitude and latitude on the data stream and sends it to the air radio station. This realizes the function of sending the base station GPS longitude and latitude data to the drone on the basis of the original communication function. After the drone obtains the base station longitude and latitude, it can use the mobile station GPS data to achieve differential positioning.

[0041] 3. Hardware Solution

[0042] The hardware structure diagram of the base station GPS is as follows: Figure 4, mainly including GPS, wireless serial port and battery. The battery supplies power to GPS and wireless serial port, and the wireless serial port transmits GPS data to the signal superimposer through the antenna. The circuit diagram is as follows Figure 5 As shown, it is powered by a lithium battery and a power switch is used to control the operation of the base station. The GPS communicates with the wireless serial port through the TX and RX ports and transmits the data to the signal superimposer.

[0043] The hardware structure diagram of the signal superimposer is as follows: Figure 6 As shown in the figure, it mainly includes a single chip microcomputer and a wireless serial port, which is powered by an external power supply. The wireless serial port data and the ground station data are simultaneously connected to the single chip microcomputer, and after superposition, they communicate with the ground station to complete the transmission of two data channels. Figure 7 As shown, the microcontroller uses STM32L051, which is a high-performance, low-power microcontroller using ARM architecture. STM32L051 has three serial ports UART1-3. The pins of UART1 are PA9 and PA10, which are connected to the ground station; the pins of UART2 are PA2 and PA3, which are connected to the wireless serial port; the pins of UART3 are PB6 and PB7, which are connected to the ground station. Capacitor C1 is a reset capacitor, connected to the reset terminal NRST of the chip. Capacitor C2 is a filter capacitor, connected in parallel at both ends of the 3.3V voltage. The signal superimposer can work normally after connecting to an external 3.3V power supply.

[0044] The total estimated price of the present invention is about 220 yuan, which accounts for a very small proportion of the cost compared with the price of a drone at the 100,000 yuan level.

[0045] Technical advantages of the present invention:

[0046] 1. The landing navigation has high accuracy, which can better solve the problem of difficulty in finding landing points for drones in the wild.

[0047] 2. Low price, high cost performance and high commercial value.

[0048] Parameters documentation:

[0049] [1] Ge Changli. Research on high-precision GPS positioning method and its application in UAV positioning system[D]. Nanjing University of Posts and Telecommunications[2023-11-18].DOI:CNKI:CDMD:2.1018.891980.

[0050] [2] Yang Jie, Zhang Fan. Comparative study of high-precision GPS differential positioning technology[J]. Mobile Communications, 2014, 38(2): 6. DOI: 10.3969 / j.issn.1006-1010.2014.02.014.

[0051] [3] Zhang Shufang, Yuan Ancun. Position differential GPS positioning system[J]. Journal of Dalian Maritime University, 2002, 28(B08):3. DOI:10.3969 / j.issn.1006-7736.2002.z1.016.

[0052] [4] Song Zebo. Research and implementation of satellite positioning error correction system based on position difference[D]. Anhui Agricultural University, 2020.

[0053] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A UAV precision landing navigation system, characterized by: It includes a mobile station GPS and a base station GPS. The base station GPS longitude and latitude data are sent to the mobile station GPS by wireless communication. The base station GPS and the mobile station GPS longitude and latitude are used to perform position differential to calculate the distance between the mobile station and the base station.

2. The UAV precise landing navigation system according to claim 1, characterized in that: When in use, the mobile station GPS is placed on the drone, and the base station GPS is placed at the landing point. The latitude and longitude data of the base station GPS are sent to the mobile station GPS of the drone by wireless means. The longitude and latitude of the base station GPS and the mobile station GPS are used to perform position differential to calculate the distance between the drone and the landing point.

3. The UAV precise landing navigation system according to claim 2, characterized in that: The GPS longitude and latitude (Lat1, Lng1) of the base station is transmitted to the UAV in real time by wireless means. The UAV obtains its own longitude and latitude (Lat2, Lng2) through the onboard mobile station GPS. The longitude difference and latitude difference between the UAV and the landing point are calculated to be ΔLng and ΔLat. The longitude difference and latitude difference represent the horizontal distance between the UAV and the landing point. The UAV is navigated to the landing point using the horizontal distance.

4. The UAV precise landing navigation system according to any one of claims 1 to 3, characterized in that: The base station GPS includes GPS, a ground radio and a signal superimposed device, and the mobile station GPS includes GPS and an aerial radio. The base station GPS sends the longitude and latitude of its own GPS to the signal superimposed device. While the signal superimposed device completes the data transmission between the ground station and the ground radio, it superimposes the longitude and latitude on the data stream and sends it to the aerial radio in the mobile station GPS. After the UAV obtains the longitude and latitude of the base station, it uses the data of the mobile station GPS to realize differential positioning.

5. The UAV precise landing navigation system according to claim 4, characterized in that: The base station GPS includes a GPS, a wireless serial port and a battery. The battery is connected to the GPS and the wireless serial port respectively. The GPS and the wireless serial port are connected. The battery supplies power to the GPS and the wireless serial port. The wireless serial port transmits GPS data to the signal superimposer through an antenna.

6. The UAV precise landing navigation system according to claim 5, characterized in that: The reference station GPS also includes a switch, one end of which is connected to the battery, and the other end of which is respectively connected to the GPS and the wireless serial port.

7. The UAV precise landing navigation system according to claim 5, characterized in that: The battery is a lithium battery, and the GPS communicates with the wireless serial port through TX and RX ports.

8. The UAV precise landing navigation system according to claim 4, characterized in that: The signal superimposer includes a single-chip microcomputer and a wireless serial port. The single-chip microcomputer is connected to the wireless serial port and the ground station respectively. The wireless serial port data and the ground station data are simultaneously connected to the single-chip microcomputer, and after superposition, they communicate with the ground station to complete the transmission of two-way data.

9. The UAV precise landing navigation system according to claim 8, characterized in that: The single chip microcomputer is STM32L051, which has three serial ports UART1-3. The pins of UART1 are PA9 and PA10, which are connected to the ground station; the pins of UART2 are PA2 and PA3, which are connected to the wireless serial port; the pins of UART3 are PB6 and PB7, which are connected to the ground radio station.

10. The UAV precise landing navigation system according to claim 9, characterized in that: The signal superimposer also includes capacitor C1 and capacitor C2. Capacitor C1 is a reset capacitor connected to the reset terminal NRST of the single chip microcomputer; capacitor C2 is a filter capacitor connected in parallel to both ends of the 3.3V voltage; the signal superimposer is connected to an external 3.3V power supply.

Images