Unmanned aerial vehicle for cable system bridge detection and safety emergency auxiliary control method

Abstract

The invention discloses an unmanned aerial vehicle for cable system bridge detection. A parachute cabin with a built-in parachute is arranged at the top of the unmanned aerial vehicle, and a buoy structure is arranged at the bottom of the unmanned aerial vehicle; the unmanned aerial vehicle is provided with a control chip for controlling flight power and opening of the parachute bay, and the unmanned aerial vehicle further comprises a gyroscope, an air pressure detector and an acceleration sensor which transmit information to the control chip. According to the device, the unmanned aerial vehicle is allowed to try to recover a stable state when encountering an abnormal condition, and the parachute is automatically unfolded if the unmanned aerial vehicle cannot be adjusted, so that the self-adaptive capability of the unmanned aerial vehicle in a complex detection environment is remarkably enhanced, and stable detection work is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of unmanned aerial vehicles, and more particularly to an unmanned aerial vehicle for cable - stayed bridge inspection and a safety emergency auxiliary control method. Background Art

[0002] Cable - stayed bridges, as key transportation infrastructure, play an important role in spanning rivers, lakes and seas and connecting road and railway traffic on both sides. With the development of China's economic society and the continuous progress of cable - stayed bridge construction technology, the span of bridges is increasing day by day. Traditional ground - based measurement tools and human - dominated inspection methods are no longer sufficient to meet the requirements of efficient and accurate inspection of such bridges.

[0003] An unmanned aerial vehicle (UAV), as a remotely controllable or autonomous flying aerial tool, with its versatility, can carry various devices to perform diverse tasks such as photography, measurement and monitoring. UAVs have the characteristics of significant cost - effectiveness, flexible and convenient operation, rapid deployment and strong real - time data transmission ability, and are particularly suitable for operations in inaccessible or narrow areas. Their long - endurance characteristics ensure the continuous execution of tasks, and when performing high - risk tasks, they can effectively reduce the risks faced by personnel and improve safety.

[0004] For the inspection of cable - stayed bridges, since such bridges are usually tall and have a large span, manual inspection is not only inefficient but also poses extremely high safety risks. The application of UAVs can avoid direct exposure of personnel to danger and significantly reduce the risk of safety accidents. UAVs can reach all key parts of the bridge, including the bridge deck, bridge towers, cables and their anchoring systems, etc., to achieve comprehensive and non - omissive inspections. Through the high - definition cameras carried, UAVs can collect high - definition image data of the bridge, and combined with image - processing technology, intelligently identify and analyze potential damages of the bridge, thus greatly improving the accuracy of disease detection.

[0005] The construction environment of cable - stayed bridges often involves broad water areas, such as rivers or the ocean, where the wind is strong. Once a UAV gets out of control and falls into the water, it will be difficult to track and retrieve. In addition, UAVs may encounter problems such as signal loss during the mission, or crash due to obstacles during flight. Summary of the Invention

[0006] Object of the Invention: To overcome the deficiencies of the background art, the first object of the present invention is to provide an unmanned aerial vehicle for cable - stayed bridge inspection;

[0007] The second objective is to provide a safety emergency auxiliary control method for the unmanned aerial vehicle (UAV) used for the inspection of cable-stayed bridges, so as to adjust the real-time acceleration of the UAV when the acceleration of the UAV is abnormal, and automatically open the parachute when the adjustment fails.

[0008] Technical solution: For the UAV used for the inspection of cable-stayed bridges disclosed by the present invention, a parachute cabin with an internal parachute is provided at the top of the UAV, and a buoy structure is provided at the bottom;

[0009] A control chip for controlling the flight power and the opening of the parachute cabin is provided on the UAV, and it further includes a gyroscope, a barometric detector, and an acceleration sensor for transmitting information to the control chip.

[0010] Furthermore, an electromagnetic adsorption switch is provided in the parachute cabin, and the electromagnetic adsorption switch is controlled by the control chip to control the opening of the parachute cabin and release the parachute.

[0011] Furthermore, the buoy structure includes two or more semi-cylindrical buoys, and the arc surface of the semi-cylindrical buoy faces downward.

[0012] Furthermore, the buoy structure is made of polyethylene material with a content exceeding 95%.

[0013] Correspondingly, the present invention also discloses a safety emergency auxiliary control method for the UAV, which is implemented based on the above-mentioned UAV used for the inspection of cable-stayed bridges, and includes the following steps:

[0014] S1. Based on the acceleration information obtained by the acceleration sensor, perform PID control to automatically adjust the acceleration of the UAV;

[0015] S2. Based on the barometric detector, obtain the real-time flight altitude of the UAV;

[0016] S3. Based on the gyroscope and the acceleration sensor, obtain the attitude of the UAV;

[0017] S4. Set the acceleration increase threshold, flight altitude descent rate threshold, and attitude abnormality threshold of the UAV. When the above thresholds exceed the range simultaneously, control the opening of the parachute cabin.

[0018] Among them, S1 specifically includes the following steps:

[0019] S1-1. Before the UAV takes off, set the theoretical acceleration range [a i , a u during the normal operation process of the UAV, and the midpoint value of the range is a0;

[0020] S1-2. After the UAV takes off, the acceleration sensor obtains the real-time acceleration a(t) during the operation process of the UAV;

[0021] S1-3. Calculate the control deviation θ(t) of the UAV acceleration;

[0022]

[0023] S1-4. Perform proportional, integral, and derivative calculations on the calculated θ(t);

[0024] First, for proportional calculation, according to the control method of generating the deviation θ(t) by the proportional system, if the acceleration value of the UAV generates a deviation, a vertically upward force will be immediately applied to the UAV to adjust the acceleration of the UAV at this time, and the adjustment strength increases with the increase of the proportional value M p and increases, thereby adaptively reducing the deviation of the system and ensuring that the UAV can still perform adaptive adjustment in case of abnormalities;

[0025] Second, for integral calculation, which is used to adjust the stability of the UAV and the positive and negative non-difference of control. The adjustment strength of the integral calculation is determined by the time constant T i and the larger this value is, the smaller its influence on the system adjustment;

[0026] Finally, for derivative calculation, which is used to adjust the deviation signal and the derivative output of the adjustment error θ(t), to ensure the effectiveness of signal control when the error changes suddenly and to ensure effective signal correction in the early stage. Its control strength is determined by the time constant T d of the derivative action;

[0027] Calculate the acceleration control amount u(t) of the UAV after takeoff:

[0028]

[0029] S1-5. Adopt error control for each sampling point and perform differential processing based on the first-order backward difference method:

[0030]

[0031] where k is the identification of the sampling moment, T is the sampling period, and θ(k) and θ(k - 1) are the error signals at the kth sampling moment and the (k - 1)th sampling moment;

[0032] S1-6. Adopt cumulative operation instead of integral operation:

[0033]

[0034] S1-7. Adopt the sampling point KT to replace the continuous time t:

[0035] t = KT (k = 0, 1, 2,...);

[0036] S1-8. Aggregate to obtain the digital PID for adjusting the drone's acceleration, and adjust the real-time acceleration of the drone according to the calculated action quantity:

[0037]

[0038] where k i = k p / T, k d = k d T d .

[0039] Furthermore, in S2, the flight altitude of the current drone is calculated by measuring the change in atmospheric pressure.

[0040] Furthermore, in S3, the following method is used to obtain the drone's attitude:

[0041] The gyroscope measures the angular velocity of the drone on the XYZ axes in real time, that is, the roll around the X axis, the pitch around the Y axis, and the yaw around the Z axis;

[0042] Combining the angular velocity data with the acceleration data, calculate the direction of gravity, and then obtain the real-time attitude angles of the drone, including the roll angle, pitch angle, and yaw angle.

[0043] Beneficial effects: Compared with the prior art, the advantages of the present invention are as follows:

[0044] 1. For the cable system bridge detection task, the present invention designs a parachute device that can dynamically adjust the acceleration of the drone during operation. This device allows the drone to attempt to self-recover to a stable state when encountering abnormal situations. If it cannot be adjusted, the parachute will be automatically deployed, significantly enhancing the adaptability of the drone in complex detection environments and ensuring the stable progress of the detection work;

[0045] 2. By integrating an advanced control system and combining the real-time data of the gyroscope, barometric detector, and acceleration sensor, the present invention can accurately judge the flight state of the drone during the cable system bridge detection process. Once an abnormality is detected, the system will immediately automatically trigger the parachute to deploy. This intelligent emergency response mechanism better meets the actual needs of cable bridge detection;

[0046] 3. For the onshore and offshore working environments that the drone may face during cable system bridge detection, the present invention cleverly combines the parachute with the buoy structure. This design enables the drone to be effectively protected whether it is over land or water when encountering a crash accident. Especially in water, the drone can float on the water surface with the help of the buoy structure, facilitating subsequent search and recovery work and effectively reducing accident losses. Description of the Drawings

[0047] Figure 1Structural diagram for the conversion between the closed and open states of the umbrella compartment of the present invention

[0048] Figure 2 Schematic diagram of the automatic acceleration adjustment method of the present invention Specific implementation manners

[0049] The technical solution of the present invention will be further described below in conjunction with the accompanying drawings and embodiments

[0050] As Figure 1 shown, the drone for cable - stayed bridge inspection, the overall fuselage structure and drive structure of the drone 1 refer to the drones of the prior art

[0051] In this embodiment, a parachute compartment 2 with an internal parachute is provided at the top of the drone 1, and a float structure 3 is provided at the bottom

[0052] The fixing method of the parachute compartment 2 and the float structure 3 is not limited. In this embodiment, it is fixed to the fuselage in a bolt - connection form

[0053] The drone 1 is provided with a control chip 4 for controlling flight power and opening the parachute compartment 2, and also includes a gyroscope, a barometric detector, and an acceleration sensor for transmitting information to the control chip 4

[0054] The parachute compartment 2 is provided with an electromagnetic adsorption switch, and the control chip 4 controls the electromagnetic adsorption switch to control the opening of the parachute compartment 2 and release the parachute

[0055] The float structure 3 includes two or more semi - cylindrical floats. The arc surface of the semi - cylindrical float faces downward and is made of polyethylene material with a content exceeding 95%

[0056] Based on the above - mentioned drone for cable - stayed bridge inspection, the present invention also discloses a drone safety emergency auxiliary control method, which specifically includes the following steps

[0057] S1. Based on the acceleration information obtained by the acceleration sensor, perform PID control to automatically adjust the acceleration of the drone. Specifically

[0058] S1 - 1. Before the drone takes off, set the theoretical acceleration range [a i , a u during the normal working process of the drone, and the mid - point value of the range is a0

[0059] S1 - 2. After the drone takes off, the acceleration sensor obtains the real - time acceleration a(t) of the drone during the working process

[0060] S1 - 3. Calculate the control deviation θ(t) of the drone acceleration

[0061]

[0062] S1-4, perform proportional, integral and differential calculations on the calculated θ(t);

[0063] First, the proportional calculation is performed. According to the control method of the proportional system to generate the deviation θ(t), if the acceleration value of the drone deviates, a vertical upward force will be immediately applied to the drone to adjust the acceleration of the drone at this time. The adjustment force varies with the proportional value M. p Increases with increase, thereby adaptively reducing the deviation of the system and ensuring that the drone can make adaptive adjustments when encountering abnormal situations;

[0064] Secondly, the integral calculation is used to adjust the stability of the drone and the positive and negative indifference of the control. The intensity of the integral calculation adjustment is determined by the time constant T i The larger the value, the smaller the impact on system adjustment;

[0065] Finally, the differential calculation is used to adjust the deviation signal and the differential output of the error θ(t) to ensure the effectiveness of signal control when the error suddenly changes and to ensure early and effective signal correction. The control strength is determined by the time constant T of the differential action. d Decide;

[0066] Calculate the acceleration control value u(t) of the drone after takeoff:

[0067]

[0068] S1-5, using error control for each sampling point, and performing differential processing based on the first-order backward difference method:

[0069]

[0070] Where k is the identification sampling time, T is the sampling period, θ(k) and θ(k-1) are the error signals at the kth sampling time and the (k-1)th sampling time;

[0071] S1-6, use cumulative operation instead of integral operation:

[0072]

[0073] S1-7, use sampling point KT instead of continuous time t:

[0074] t = KT (k = 0, 1, 2, ...);

[0075] S1-8, summarize the UAV acceleration adjustment digital PID, and adjust the UAV's real-time acceleration according to the calculated action amount:

[0076]

[0077] where k i = k p / T, k d = k d T d .

[0078] S2. Based on the barometric detector, calculate the current flight altitude of the UAV by measuring the change in atmospheric pressure.

[0079] S3. Obtain the UAV attitude based on the gyroscope and acceleration sensor. Specifically:

[0080] The gyroscope measures the angular velocity of the UAV on the XYZ axes in real time, that is, the roll around the X axis, the pitch around the Y axis, and the yaw around the Z axis. These data are usually expressed in degrees per second (° / s).

[0081] Combine the angular velocity data with the acceleration data to calculate the direction of gravity, and then obtain the real-time attitude angles of the UAV, including the roll angle, the pitch angle, and the yaw angle.

[0082] In this embodiment, if the roll angle and pitch angle of the UAV exceed the range of ±30 degrees or the angular velocity suddenly changes abnormally (such as a sudden large rotation), it is determined that the attitude is abnormal.

[0083] S4. Set the UAV acceleration increase threshold, the flight altitude descent rate threshold, and the attitude abnormality threshold. When the above thresholds are all out of range at the same time, that is, during the UAV acceleration adjustment process, it is detected that the UAV is always in a state of continuous and sharp acceleration increase, the altitude is continuously and sharply decreasing, and the attitude of the UAV is continuously abnormal, then control the parachute compartment to open and release the parachute.

Claims

1. A UAV for cable system bridge inspection, characterized by: The top of the drone (1) is provided with a parachute cabin (2) with a built-in parachute, and the bottom is provided with a buoy structure (3); The unmanned aerial vehicle (1) is provided with a control chip (4) for controlling flight power and the opening of the parachute cabin (2), and also includes a gyroscope, an air pressure detector, and an acceleration sensor for transmitting information to the control chip (4).

2. The UAV for cable system bridge inspection according to claim 1, characterized in that: The parachute compartment (2) is provided with an electromagnetic attraction switch, and the electromagnetic attraction switch is controlled by a control chip (4) to control the parachute compartment (2) to open and release the parachute.

3. The UAV for cable system bridge inspection according to claim 1, characterized in that: The buoy structure (3) comprises two or more semi-cylindrical buoys, wherein the arc surfaces of the semi-cylindrical buoys face downwards.

4. The UAV for cable system bridge inspection according to claim 1, characterized in that: The buoy structure (3) is made of polyethylene material with a content exceeding 95%.

5. A safety emergency auxiliary control method for an unmanned aerial vehicle, characterized in that: The implementation of the drone for cable system bridge inspection according to claim 1 includes the following steps: S1, based on the acceleration sensor to obtain the acceleration information of the drone to automatically adjust the acceleration of the drone through PID control; S2, obtaining the real-time flight altitude of the drone based on the air pressure detector; S3, obtaining the drone attitude based on the gyroscope and acceleration sensor; S4. Set the drone acceleration increase threshold, flight altitude descent rate threshold and attitude abnormality threshold. When the above thresholds exceed the range at the same time, the parachute cabin is controlled to open.

6. The UAV safety emergency auxiliary control method according to claim 5 is characterized in that: S1 specifically includes the following steps: S1-1. Before the drone takes off, set the theoretical acceleration range of the drone’s normal operation process [a i ,a u ], the midpoint of the range is a0; S1-2, after the drone takes off, the acceleration sensor obtains the real-time acceleration a(t) of the drone during operation; S1-3, calculate the control deviation θ(t) of the UAV acceleration; S1-4, perform proportional, integral and differential calculations on the calculated θ(t); First, the proportional calculation is performed. According to the control method of the proportional system to generate the deviation θ(t), if the acceleration value of the drone deviates, a vertical upward force will be immediately applied to the drone to adjust the acceleration of the drone at this time. The adjustment force varies with the proportional value M. p Increases with increase, thereby adaptively reducing the deviation of the system and ensuring that the drone can make adaptive adjustments when encountering abnormal situations; Secondly, the integral calculation is used to adjust the stability of the drone and the positive and negative indifference of the control. The intensity of the integral calculation adjustment is determined by the time constant T i The larger the value, the smaller the impact on system adjustment; Finally, the differential calculation is used to adjust the deviation signal and the differential output of the error θ(t) to ensure the effectiveness of signal control when the error suddenly changes and to ensure early and effective signal correction. The control strength is determined by the time constant T of the differential action. d Decide; Calculate the acceleration control value u(t) of the drone after takeoff: S1-5, using error control for each sampling point, and performing differential processing based on the first-order backward difference method: Where k is the identification sampling time, T is the sampling period, θ(k) and θ(k-1) are the error signals at the kth sampling time and the (k-1)th sampling time; S1-6, use cumulative operation instead of integral operation: S1-7, use sampling point KT instead of continuous time t: t = KT (k = 0, 1, 2, ...); S1-8, summarize the UAV acceleration adjustment digital PID, and adjust the UAV's real-time acceleration according to the calculated action amount: Where k i =k p / T,k d =k d T d .

7. The UAV safety emergency auxiliary control method according to claim 5 is characterized in that: In S2, the current flight altitude of the UAV is calculated by measuring the change in atmospheric pressure.

8. The UAV safety emergency auxiliary control method according to claim 5 is characterized in that: The drone attitude in S3 is obtained using the following method: The gyroscope measures the angular velocity of the drone on the XYZ axis in real time, namely the roll around the X axis, the pitch around the Y axis, and the yaw around the Z axis; By combining the angular velocity data with the acceleration data, the direction of gravity is calculated, and then the real-time attitude angle of the drone is obtained, including the roll angle, pitch angle and yaw angle.

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