A UAV Bridge Underpass Inspection System Based on Dual-Aircraft Cooperative Positioning

Abstract

The present invention discloses an unmanned aerial vehicle bridge bottom inspection system based on dual-machine collaborative positioning, including a relay machine and an inspection machine. The relay machine is equipped with an infrared beacon light positioning transmitter, a laser target, etc., and locates itself through satellites, and provides auxiliary positioning for the inspection machine when necessary. The inspection machine is equipped with binocular infrared beacon receivers and other equipment. On the outside of the bridge, the two machines use satellite signals to locate and cooperate. When entering the bottom of the bridge, the inspection machine relies on laser ranging to avoid collision. When the satellite signal is weak, it switches to the relay machine's auxiliary positioning mode, calculates its own coordinates, and the relay machine remains synchronously locked with the inspection machine to complete the bridge bottom scan. The system improves positioning accuracy and safety, simplifies structure, reduces costs, realizes efficient and accurate inspections, provides strong support for bridge maintenance, and has broad application prospects.

Description

Technical Field

[0001] This paper deals with a UAV bridge bottom inspection system based on dual-machine collaborative positioning. Background Art

[0002] Bridges are an important part of transportation infrastructure, and their safety is directly related to the smoothness and safety of transportation.

[0003] Bridge bottom inspection is crucial to timely discover bridge structural defects and ensure the service life of bridges. Traditional bridge bottom inspection methods, such as manual observation with large equipment or ground telescopes, have problems such as low efficiency, low detection accuracy, high cost, and difficulty in fully detecting subtle hidden dangers under the bridge.

[0004] With the development of drone technology, drone inspection has provided a new way for bridge bottom inspection. However, in the bridge bottom environment, due to the obstruction of satellite signals by the bridge body, the satellite positioning system of the drone cannot work properly or the accuracy is greatly reduced, making it difficult for the drone to achieve accurate autonomous flight and inspection operations, which seriously affects the inspection effect and may even cause safety accidents.

[0005] Therefore, it is of great practical significance to develop a system and method that can achieve high-precision positioning and safety inspection of UAVs under the condition of weak satellite signals under the bridge. Summary of the invention

[0006] The present invention aims to provide a UAV bridge bottom inspection system based on dual-machine collaborative positioning. Through the collaborative work of the relay machine and the inspection machine, combined with precise positioning and height detection mechanisms, the safety and high-precision operation of the inspection machine during bridge bottom inspection can be ensured, thereby reducing system costs and improving inspection efficiency.

[0007] A UAV bridge bottom inspection system based on dual-machine collaborative positioning, the system consists of:

[0008] Repeater: The repeater is equipped with an infrared beacon light positioning transmitter, a laser target, an onboard computer and a satellite RTK positioning device. It realizes its own positioning by receiving real satellite signals, and uses infrared beacons, laser targets and other equipment to provide auxiliary positioning for the inspection machine.

[0009] Inspection machine: equipped with binocular infrared beacon receiver, laser rangefinder transmitter, satellite RTK positioning device, onboard computer and inspection equipment;

[0010] When both aircraft are flying outside the bridge, each uses its own satellite positioning module to receive satellite signals, obtain its own positioning coordinates, and report its position coordinates, heading angle, altitude and other parameters to the other aircraft's onboard computer in real time through the communication data link and cluster control platform;

[0011] By comparing the relative positions of the two machines, the relay machine automatically controls itself to a synchronous locking state with a fixed distance, relative azimuth, same heading angle, and same altitude as the inspection machine's motion trajectory, so that the infrared beacon and laser target are in the near-center area of ​​the inspection machine's infrared beacon receiver's field of view;

[0012] When the inspection aircraft begins to fly under the bridge:

[0013] On the one hand, the inspection machine uses the laser rangefinder to obtain the relative height information from the bottom of the bridge to prevent the height from colliding with the bottom of the bridge.

[0014] On the other hand, when the inspection aircraft flight control detects that the satellite signal is weak, it switches to the mode of auxiliary positioning through the repeater. In this mode, the inspection aircraft obtains the relative azimuth and rough distance with the repeater through the binocular infrared beacon receiver, and obtains the precise distance with the repeater through the front laser ranging device. It calculates its own real-time longitude and latitude positioning coordinates through the obtained real-time position coordinates and heading angle of the repeater, and sends the positioning coordinates, heading angle, and altitude to the repeater in real time through the communication data link;

[0015] In this way, the repeater on the outside of the bridge can remain synchronized with the inspection aircraft in terms of position, relative azimuth, heading angle and altitude. The inspection aircraft completes a comprehensive scan of the bridge bottom according to the predetermined bridge bottom flight route to obtain accurate bridge data.

[0016] Remote control system: As the control core of the entire system, the bridge data obtained through drone aerial survey in the early stage has established an accurate three-dimensional model of the bridge in the system. According to the bridge model, the synchronous flight routes of the relay aircraft and the inspection aircraft are planned, and the flight actions between the two are coordinated to ensure that they work together to achieve efficient and safe bridge bottom inspection.

[0017] Capture and positioning principle between relay machine and inspection machine

[0018] Infrared pre-positioning: The repeater continuously emits infrared signals, which form a certain signal field in space. During the flight, after the inspection aircraft receives the infrared signal, its binocular infrared beacon receiving device preliminarily determines its position and approximate distance relative to the repeater based on the binocular ranging principle. This pre-positioning method can quickly establish the relative position relationship between the two at a long distance, providing a basis for subsequent precise positioning.

[0019] Laser precision positioning: Based on infrared pre-positioning, the laser rangefinder of the inspection machine emits a laser beam to the laser target of the relay machine. The laser rangefinder of the inspection machine receives the laser signal reflected back by the laser target, and calculates the distance to the relay machine based on the speed of light by accurately measuring the round-trip time of the laser. At the same time, combined with the orientation information obtained by the previous infrared positioning, the spatial geometric relationship and coordinate transformation algorithm are used to accurately calculate the position coordinates of the inspection machine in space, and achieve accurate capture and positioning with the relay machine. This positioning method has the characteristics of high precision and high reliability, and can meet the requirements of bridge bottom inspection for drone positioning accuracy.

[0020] Among them, the dual-machine collaborative working principle:

[0021] 1. Flight coordination outside the bridge

[0022] When the two aircraft fly outside the bridge, each uses the satellite positioning module to receive satellite signals, obtain positioning coordinates, heading angles, altitude and other parameters, and report them to the other party's onboard computer in real time through the communication data link and cluster control platform. By comparing the relative positions of the two aircraft, the relay aircraft automatically controls itself to maintain a synchronous lock state with the inspection aircraft at a fixed distance, relative azimuth, the same heading angle and the same altitude, ensuring that the infrared beacon and laser target are in the near-center area of ​​the inspection aircraft's infrared beacon receiver field of view.

[0023] 2. Bridge bottom inspection coordination

[0024] When the inspection machine enters the bottom of the bridge to fly, on the one hand, it uses the upper laser ranging device to obtain the relative height information with the bottom of the bridge to prevent collision with the bottom of the bridge. On the other hand, when the satellite signal is detected to be weak, it switches to the relay auxiliary positioning mode. At this time, the inspection machine obtains the relative azimuth and rough distance with the relay through the binocular infrared beacon receiver, and obtains the precise distance through the front laser ranging device. Combined with the real-time position coordinates and heading angle of the relay, it calculates its own real-time longitude and latitude positioning coordinates, and sends the positioning coordinates, heading angle and altitude to the relay in real time. The relay machine maintains a synchronous locking state with the inspection machine in position, relative azimuth, heading angle and altitude on the outside of the bridge, ensuring that the inspection machine stably and accurately completes the scan according to the predetermined bridge bottom flight route and obtains accurate bridge data.

[0025] Preferably, the infrared beacon positioning transmitting device adopts an 850-nanometer near-infrared light source, and the infrared binocular beacon receiving device is equipped with a corresponding high-sensitivity infrared light sensor.

[0026] Preferably, the communication between the remote control system and the relay machine and the inspection machine adopts multi-band redundant communication technology, including 2.4GHz, 5.8GHz and other frequency bands. When one frequency band is interfered, it automatically switches to other frequency bands.

[0027] Preferably, the flight altitude control device of the inspection machine is deeply coupled with the laser rangefinder, and the flight altitude is adjusted according to the distance information from the bottom of the bridge fed back in real time by the laser rangefinder to maintain it within a preset safe altitude range with an error not exceeding ±0.5 meters.

[0028] Preferably, the infrared beacon positioning and transmitting device is installed in a fixed position on the repeater. The repeater automatically adjusts its own position and heading angle by comparing the relative position and azimuth with the inspection machine, so that the infrared beacon and laser target are always in the near-center area of ​​the field of view of the infrared beacon receiver of the inspection machine.

[0029] Preferably, the remote control system has fault diagnosis and early warning functions, monitors the key equipment status of the relay machine and the inspection machine in real time, and issues early warning information in a timely manner when an abnormality is detected.

[0030] Preferably, when an emergency such as communication interruption or low battery occurs, the optimal return route is automatically planned for the relay machine and the inspection machine, and a return instruction is sent through a backup communication link.

[0031] Preferably, the body surfaces of the relay machine and the inspection machine are coated with an anti-corrosion coating.

[0032] Beneficial effects:

[0033] 1. Excellent positioning accuracy and high security guarantee

[0034] The present invention uses the infrared and laser positioning technology of the repeater to assist the inspection machine, achieving high-precision positioning in the complex environment under the bridge. The infrared signal and laser beam emitted by the repeater provide the inspection machine with azimuth reference and precise distance measurement, respectively. Combined with the algorithm, it ensures that the inspection machine obtains accurate position coordinates in real time. At the same time, the inspection machine uses a laser rangefinder to continuously monitor the distance to the bottom of the bridge, strictly controlling the error within a very small range, and can adjust the flight altitude in time, effectively avoiding the risk of collision with the bottom of the bridge due to misjudgment of altitude, greatly improving the safety of the inspection operation.

[0035] 2. Significant system simplification and cost-effectiveness improvement

[0036] Compared with the traditional complex multi-relay cluster solution, this system adopts a single-relay, dual-machine coordinated system structure, which greatly reduces the number and types of equipment. This not only reduces the purchase cost of equipment, but also significantly reduces the workload and difficulty of equipment maintenance. The reduction in system complexity improves overall reliability and reduces the failure rate, making it more economically feasible and providing a more cost-effective solution for long-term bridge inspection work.

[0037] 3. Efficient and accurate inspection capabilities

[0038] With precise positioning and height control mechanisms, the inspection aircraft can maintain a stable posture and precise route when flying under the bridge. It can efficiently scan the bottom of the bridge and accurately collect structural data such as cracks, corrosion, and deformation on the bottom of the bridge using mounted high-definition cameras, thermal imagers, and other inspection equipment. These rich and accurate data provide a strong basis for bridge maintenance decisions, helping bridge management departments to promptly discover potential safety hazards, formulate scientific and reasonable maintenance plans, and ensure the long-term safe use of bridges. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a schematic diagram of a UAV bridge bottom inspection system based on dual-machine collaborative positioning measuring under a large bridge. DETAILED DESCRIPTION

[0040] In order to deepen the understanding of the present invention, the present invention will be further described in detail below with reference to embodiments and drawings. The embodiments are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention.

[0041] Embodiment 1:

[0042] A UAV bridge bottom inspection system based on dual-machine collaborative positioning includes the following parts:

[0043] Repeater: The repeater is equipped with an infrared beacon light positioning transmitter, a laser target, an onboard computer and a satellite RTK positioning device. It realizes its own positioning by receiving real satellite signals, and uses infrared beacons, laser targets and other equipment to provide auxiliary positioning for the inspection machine.

[0044] Inspection machine: equipped with binocular infrared beacon receiver, laser rangefinder transmitter, satellite RTK positioning device, onboard computer and inspection equipment;

[0045] The inspection method includes the following steps:

[0046] 1. Inspection preparation

[0047] The relay aircraft takes off to the specified altitude, receives satellite signals to complete its own positioning, turns on the infrared beacon light positioning transmitter, and enters the inspection route along one side of the bridge to wait.

[0048] The inspection aircraft takes off and flies outside the bridge, using the satellite positioning module to receive satellite signals for navigation. At the same time, it turns on the laser ranging device to continuously monitor the distance to the bottom of the bridge and approaches the bottom of the bridge.

[0049] 2. Synchronization of formation and positioning

[0050] When the inspection machine approaches the starting position of the bridge bottom inspection, it establishes a communication connection with the repeater and receives the infrared beacon signal transmitted by the repeater. The repeater adjusts the position and angle and locks the synchronization according to the relative position relationship to complete the construction of the inspection formation.

[0051] 3. Bridge bottom inspection work

[0052] After the inspection aircraft enters the inspection area under the bridge, it accurately adjusts its flight attitude and position based on the positioning signal from the repeater and its own laser ranging information, maintains a safe and stable relative height with the bottom of the bridge, and keeps the infrared receiving device and laser ranging device aimed at the repeater at all times, and flies along the planned route.

[0053] The mounted inspection equipment is used to conduct a comprehensive scan of the bottom of the bridge to collect structural data on the bottom of the bridge, such as cracks, corrosion, deformation and other information, and transmit the data to the data processing center in real time.

[0054] The repeater maintains precise synchronous flight with the inspection aircraft on the outside of the bridge, updating the positioning signal in real time to ensure the inspection aircraft's accurate positioning in the weak signal area at the bottom of the bridge.

[0055] 4. Inspection completion and data analysis

[0056] After completing all inspection tasks under the bridge, the inspection aircraft will fly out of the area under the bridge along the predetermined route and return to the designated landing point for landing.

[0057] The relay aircraft also returns to the landing point and lands. The data processing center conducts detailed analysis and processing of the collected bridge data, and generates an assessment report containing information such as the location and extent of bridge defects, providing accurate data support for bridge maintenance.

[0058] In order to achieve dual-machine collaborative positioning, the positioning and height detection principles are as follows:

[0059] 1. Repeater assisted positioning

[0060] Infrared positioning: The repeater transmits an infrared signal. After receiving it, the inspection machine determines its azimuth and distance relative to the repeater based on the binocular ranging principle to achieve rapid and approximate positioning.

[0061] Laser positioning: The repeater emits a laser beam, and the laser receiving device on the inspection machine receives the laser signal. The distance to the repeater is accurately calculated by measuring the laser flight time, and the azimuth obtained by infrared positioning is combined to obtain the precise plane position coordinates through triangulation.

[0062] 2. Inspection machine height detection

[0063] The inspection machine uses a laser rangefinder to emit laser pulses to the bottom of the bridge, calculates the vertical distance to the bottom of the bridge based on the laser reflection time, transmits the distance information to the flight altitude control device in real time, and adjusts the flight altitude to maintain a safe distance.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A UAV bridge bottom inspection system based on dual-machine collaborative positioning, characterized in that: Includes the following sections: Repeater: The repeater is equipped with an infrared beacon light positioning transmitter, a laser target, an onboard computer and a satellite RTK positioning device. It realizes its own positioning by receiving real satellite signals, and uses infrared beacons, laser targets and other equipment to provide auxiliary positioning for the inspection machine. Inspection machine: equipped with binocular infrared beacon receiver, laser rangefinder transmitter, satellite RTK positioning device, onboard computer and inspection equipment; When both aircraft are flying outside the bridge, each uses its own satellite positioning module to receive satellite signals, obtain its own positioning coordinates, and report its position coordinates, heading angle, altitude and other parameters to the other aircraft's onboard computer in real time through the communication data link and cluster control platform; By comparing the relative positions of the two machines, the relay machine automatically controls itself to a synchronous locking state with a fixed distance, relative azimuth, same heading angle, and same altitude as the inspection machine's motion trajectory, so that the infrared beacon and laser target are in the near-center area of ​​the inspection machine's infrared beacon receiver's field of view; When the inspection aircraft begins to fly under the bridge: On the one hand, the inspection machine uses the laser rangefinder to obtain the relative height information from the bottom of the bridge to prevent the height from colliding with the bottom of the bridge. On the other hand, when the inspection aircraft flight control detects that the satellite signal is weak, it switches to the mode of auxiliary positioning through the repeater. In this mode, the inspection aircraft obtains the relative azimuth and rough distance with the repeater through the binocular infrared beacon receiver, and obtains the precise distance with the repeater through the front laser ranging device. It calculates its own real-time longitude and latitude positioning coordinates through the obtained real-time position coordinates and heading angle of the repeater, and sends the positioning coordinates, heading angle, and altitude to the repeater in real time through the communication data link; In this way, the repeater on the outside of the bridge can remain synchronized with the inspection aircraft in terms of position, relative azimuth, heading angle and altitude. The inspection aircraft completes a comprehensive scan of the bridge bottom according to the predetermined bridge bottom flight route to obtain accurate bridge data.

2. The unmanned aerial vehicle bridge bottom inspection system based on dual-machine cooperative positioning according to claim 1 is characterized in that: The infrared beacon positioning transmitting device adopts an 850-nanometer near-infrared light source, and the infrared binocular beacon receiving device is equipped with a corresponding high-sensitivity infrared light sensor.

3. The unmanned aerial vehicle bridge bottom inspection system based on dual-machine cooperative positioning according to claim 1 is characterized in that: The communication between the remote control system and the relay machine and the inspection machine adopts multi-band redundant communication technology, including 2.4GHz, 5.8GHz and other frequency bands. When one frequency band is interfered, it automatically switches to other frequency bands.

4. The unmanned aerial vehicle bridge bottom inspection system based on dual-machine cooperative positioning according to claim 1 is characterized in that: When flying under a bridge, the inspection aircraft's flight altitude control is deeply coupled with the upper laser rangefinder. Based on the distance information from the bridge bottom fed back in real time by the laser rangefinder, the aircraft adjusts its flight altitude to maintain within the preset safety altitude range with an error of no more than ±0.5 meters.

5. The unmanned aerial vehicle bridge bottom inspection system based on dual-machine collaborative positioning according to claim 1 is characterized in that: The infrared beacon positioning and transmitting device is installed in a fixed position on the repeater. The repeater automatically adjusts its own position and heading angle by comparing the relative position and azimuth with the inspection machine, so that the infrared beacon and laser target are always in the near-center area of ​​the field of view of the infrared beacon receiver of the inspection machine.

6. The unmanned aerial vehicle bridge bottom inspection system based on dual-machine collaborative positioning according to claim 1 is characterized in that: The remote control system has fault diagnosis and early warning functions, monitors the key equipment status of relay machines and inspection machines in real time, and issues early warning information in a timely manner when an abnormality is detected.

7. The unmanned aerial vehicle bridge bottom inspection system based on dual-machine cooperative positioning according to claim 6 is characterized in that: When emergencies such as communication interruption and low battery occur, the remote control platform automatically plans the optimal return route for the relay and inspection aircraft, and sends return instructions through the backup communication link.

8. The unmanned aerial vehicle bridge bottom inspection system based on dual-machine cooperative positioning according to claim 1 is characterized in that: The body surfaces of the relay machine and the inspection machine are coated with an anti-corrosion coating.

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