Remote communication interaction link system of electric power inspection unmanned aerial vehicle

Abstract

According to the remote communication interaction link system of the electric power inspection unmanned aerial vehicle, a data link solution which is high in reliability, good in safety, high in integration level and long in transmission distance is provided based on the structure and mechanism of a UAV data link. The design and construction of a power inspection UAV data link system hardware scheme are completed, data link system hardware equipment suitable for a power inspection UAV system is designed, the characteristics, the configuration mode and the installation mode of the data link system hardware equipment are described in detail, and an anti-interference design is provided for a power UAV control panel. A whole set of communication protocol is designed according to an unmanned aerial vehicle data link system, data congestion is demonstrated, data traffic is reasonably arranged through design and calculation, and generation of data congestion is prevented. All parameter indexes of the limit communication distance of the system are defined, and the data link design scheme is high in reliability, good in safety, high in integration level and long in transmission distance.

Description

Technical Field

[0001] The present application relates to an electric power UAV communication link system, and more particularly to an electric power inspection UAV long-distance communication interactive link system, belonging to the field of UAV communication information processing technology. Background Art

[0002] The power inspection drone is an industry-level UAV used for power transmission line inspections, power corridor inspections, line aging inspections, insulator damage, corridor vegetation growth, and illegal building surveys. It generally works in complex field environments at an altitude of 0-3km.

[0003] Power inspection UAV has great advantages over manual work. Traditional manual line inspection requires manual inspection of poles and towers. Because a large number of transmission lines are distributed in the wild, the terrain is very complex, and the natural environment is relatively harsh, manual inspections often face great risks to personnel safety and low efficiency. Often only a few poles and towers can be inspected in a day. Power lines and pole tower accessories are exposed to the natural environment for a long time, and are subject to continuous mechanical tension, line aging, lightning, insulator damage, and human influence, resulting in tower collapse, corrosion, broken strands, wear, and stress damage. They must be repaired or replaced in time. Insulators are also at risk of being damaged by lightning. Discharge of transmission lines caused by tree growth can also cause power accidents. There are also accidents of theft of poles and towers, which need to be dealt with in a timely manner. Therefore, traditional manual line inspections require regular and fixed-point repeated inspections of transmission lines to promptly discover various safety hazards. However, because transmission lines are often in deserted areas, far away from roads, or even in deep mountains, manual line inspections are very difficult.

[0004] The emergence of power inspection drones has brought an innovative revolution to power inspection work. UAVs overlook the towers from the air, and all hidden dangers are clearly visible. At the same time, it saves power workers from the hard work of climbing mountains and wading through water. UAVs have fast inspection speeds and accurate fault location. They can take close-up photos of problem points for archiving. UAVs are powered by batteries, which can be charged repeatedly without polluting the environment. In addition, the flight cost is very low and there is almost no loss, which has brought great convenience to power grid inspection.

[0005] UAV line inspection only requires the inspector to take off the UAV from a location several kilometers away from the pole tower. After it automatically flies to the pole tower, the inspector can control the UAV to take photos or videos, and quickly locate the problem points by watching them in real time or analyzing the sent back images later. This approach saves time and effort, and the line inspection efficiency is 30-50 times higher than that of manual line inspection.

[0006] Although power inspection drones have brought about efficiency improvements, they also face many technical difficulties. This is because power inspection drones usually work in mountainous areas where it is inconvenient for people to enter. They need to deal with complex mountain terrain, turbulence, high altitude, low temperature, and high humidity. At the same time, power transmission lines will generate strong electric fields and electromagnetic waves, which will cause great interference to the UAV's navigation system and communication system. These are all practical difficulties that power inspection drones must deal with.

[0007] According to the "Inspection Standards for Unmanned Helicopter Inspection Systems for Overhead Transmission Lines", the typical use scenario of inspection drones is to replace manual inspection work in the field. The operator takes off the UAV from a few hundred meters to two kilometers away. The UAV arrives near the target tower according to the preset route. The operator controls the position and shooting angle of the aircraft according to the returned data and images to take photos or videos, and then flies to the next level of tower along the line or returns. This operation method naturally divides the UAV inspection system into a ground station part and a carrier part. The two parts are required to maintain stable real-time communication, and the communication distance must be guaranteed to be more than two kilometers.

[0008] In summary, the existing technology still has several problems and defects. The key technical difficulties of the communication interaction link of the power inspection drone are as follows:

[0009] (1) The communication distance is long and communication interaction is difficult. The use environment of the power inspection drone data link system is complex, the amount of data transmitted is large, and the environmental interference is large. The communication distance is difficult to guarantee. The communication distance of the existing inspection drone system in actual use is mostly less than 2 kilometers. When the distance increases, the communication quality decreases rapidly and cannot meet the requirements of power inspection;

[0010] (2) Control delay is difficult. UAVs fly at high speeds and the air environment is complex. High control delay may cause the UAV to crash into obstacles, especially power lines, due to lack of avoidance. The power inspection UAV system requires the UAV to respond quickly to ground control signals. Generally, the control delay is required to be less than 20ms. However, when the amount of transmitted data is large and the types of data are many, the delay is often difficult to control and may even cause data congestion. Current UAV communications cannot solve this problem.

[0011] (3) Data security cannot be guaranteed. Power inspection UAVs have high requirements for data security. In order to prevent others from maliciously monitoring data and illegally accessing the UAV system, or malicious operations that pose a greater threat to power grid security, the data link must be encrypted to prevent illegal intrusion into the data link. The reliability of the communication interaction link is not high.

[0012] (4) Insufficient data bandwidth. The data transmitted in the power inspection UAV system includes remote control data, telemetry data, and image data. The data volume of these data is large and the data types are diverse. During the transmission process, high requirements are placed on the bandwidth of the communication interaction link. The existing UAV communication link is difficult to provide the bandwidth for all the above data over a long distance for a long time.

[0013] (5) Strong electromagnetic interference and electrostatic interference. Power lines will generate strong electromagnetic radiation. High-power electromagnetic radiation will generate repressive electromagnetic interference, which will cause the carrier signal to be unable to be recognized and interfere with the data link system. In mild cases, it will affect the communication quality, and in severe cases, it will even cause the communication system to burn out. At the same time, the electrostatic discharge of the power grid will break down electronic components, causing equipment damage. The pulse interference generated by electrostatic discharge will cause the communication system to malfunction or even burn out. This is a serious problem faced by drones when inspecting power grids. The inability to ensure safety will prevent it from being promoted to practical applications.

[0014] (6) The existing technology lacks the design of UAV communication interaction link system for power inspection, lacks the design of UAV communication interaction link hardware architecture, configuration mode, and installation method based on the different characteristics of terminal equipment and the data it transmits, and lacks UAV communication link that is resistant to electromagnetic interference; lacks UAV communication interaction protocol for power inspection, lacks demonstration and calculation of data blocking, and is prone to data blocking; lacks UAV communication interaction protocol modulation method, lacks corresponding CUBK modulation, uplink control data, downlink telemetry data, and remote control protocol, which ultimately leads to low reliability, poor security, low integration, and short transmission distance of power inspection UAV data link, and cannot be promoted to large-scale practical applications. Summary of the invention

[0015] This application designs and implements a data link system solution for electric power inspection UAVs that meets the requirements of national standards. The solution can fully meet the requirements of the State Grid for the communication and interactive link system of electric power inspection UAVs. Based on the structure and mechanism of the UAV data link, a data link solution with high reliability, good security, high integration and long transmission distance is proposed. The design and construction of the hardware solution of the electric power inspection UAV data link system are completed. Taking into account the various characteristics of each hardware device, the data link system hardware equipment suitable for the electric power inspection UAV system is designed, and its characteristics, configuration methods, and installation methods are described in detail. The anti-interference design is proposed for the electric power UAV control board. A complete set of communication protocols is designed according to the UAV data link system, which can meet the data transmission application of the electric power inspection UAV, and the data blocking is demonstrated. Through design and calculation, the data flow is reasonably arranged to prevent the occurrence of data blocking. A test method for the frame loss rate of the electric power inspection UAV communication and interactive link system is designed, and the performance of this application is tested according to the test method. The various parameter indicators of the extreme communication distance of this communication and interactive link system are clarified, which is of great significance for guiding the actual work of the electric power inspection UAV.

[0016] In order to achieve the above technical effects, the technical solutions adopted in this application are as follows:

[0017] Long-distance communication interactive link system for power inspection UAVs, uplink settings for data request instructions, mode settings, pointing flight, waypoint planning, pod control instructions, downlink settings for power UAV parameters, attitude information protocol, flight controller output values, remote control input value monitoring protocol;

[0018] First, the overall design of the UAV communication interaction link system, including: power inspection UAV system architecture, UAV platform, inspection system ground station system, inspection UAV data link equipment, power UAV control board; build the power inspection UAV data link system hardware, connect and interact with other systems through the communication link, make specific improvements to the UAV communication interaction link system according to the different characteristics of the terminal equipment and the data it transmits, optimize the hardware architecture, configuration mode, and installation method, and propose an anti-electromagnetic interference UAV communication link based on the power UAV control board;

[0019] Second, the communication interaction protocol of the power inspection UAV includes: UAV communication interaction data link setting, data link frame format, protocol communication mode, and link congestion control; UAV communication interaction is divided into 6 data according to the physical connection, and the protocol communication adopts a quasi-master-slave communication mode. The power UAV control board is the host and the flight controller is the slave. The power UAV control board and the flight controller can communicate one-to-one, perform demonstration calculations on data blocking, arrange and set data flow, and prevent data blocking;

[0020] Third, the UAV communication interaction protocol modulation method, including: CUBK modulation, uplink control data, downlink telemetry data, remote control protocol; uplink control data is the control instructions issued by the ground station to the flight controller and pod, which are divided into pod control instructions and flight control instructions and data requests; downlink telemetry data is the feedback information transmitted by the UAV end to the ground, including the battery voltage fed back by the flight controller, flight mode UAV parameters, AHRS heading information, navigation positioning information, flight controller output value, and remote control input value.

[0021] Furthermore, the power inspection UAV system architecture: The power inspection UAV system is divided into two parts: the mission carrier part and the ground station; the mission carrier is a multi-rotor UAV, and the UAV platform includes a flight control system and a pod system; the mission payload is a visible light or infrared pod, which takes photos and records videos, and the video and UAV telemetry information are transmitted back to the ground station in real time;

[0022] The ground station consists of a receiving station, a portable proportional remote controller and an industrial-grade computer. The receiving station consists of a data transmission, a WIFI module and a picture transmission receiving terminal, which are packaged to facilitate operation. The ground station computer monitors the real-time data of the mission carrier and the returned video information, and controls and modulates all the mission carrier at the same time. The remote controller controls the flight attitude of the UAV and controls the pod to take pictures, record videos and focus.

[0023] Three wireless links are used for data transmission. The frequency of each link is different to avoid co-frequency interference. At the same time, all three links use digital signal transmission. The links complement and back up each other to ensure the safety of the power inspection drone system. At the same time, the structure of each link is clear, and the equipment is streamlined to a minimum to reduce the impact of equipment failure.

[0024] Furthermore, the UAV platform:

[0025] (1) Flight controller system: It is composed of computing chips, sensors and other peripheral circuits. The sensors include navigation and positioning module, electronic magnetic compass, barometric altimeter, three-axis accelerometer and three-axis gyroscope. The flight controller system obtains the attitude, speed, altitude and navigation and positioning information of the UAV by collecting data from various sensors. It calculates and processes this information and sends out control signals to maintain the UAV's self-stabilizing flight and execute mission actions. The external interface of the flight controller system adopts UARTR serial port with a baud rate of 115200Kbps. The transmitted data includes the calculated UAV attitude information and navigation and positioning information, which are all transmitted to the outside through the serial port, and the control instructions from the ground are received at the same time.

[0026] (2) Infrared pod: It is an important mission payload of the power inspection UAV. It collects images of the target location. The pod consists of a gimbal and a camera. The camera captures infrared images and transmits them to the image transmission module through the HDMI interface. The gimbal system has a built-in three-axis gyroscope, accelerometer chip and magnetic compass chip. The main controller controls the direction of the camera by continuously adjusting the three-axis brushless motor to offset the deflection and jitter of the UAV, making the camera system image stable. The main controller communicates with the power UAV control board through the serial port, receives control instructions, and controls the camera to focus and take pictures.

[0027] Furthermore, the UAV communication interaction data link setting: the UAV communication interaction is divided into 6 data links:

[0028] Link 1, remote control command: This link is the SBUS control command issued by the remote control receiver. The effective information is the control information of the remote control receiver on the pod, that is, controlling the pod to move up, down, left, and right, and controlling the camera to take pictures and record videos. This link has low data volume, fast update rate, and high real-time requirements;

[0029] Link 2, flight controller control instructions: This link transmits the control instructions from the ground station to the flight controller, including changing the flight mode, pointing the flight, and setting parameter information. This link has a large amount of data, a very low update rate, and low real-time requirements;

[0030] Link 3, flight controller feedback information: This link is the data information sent back by the flight controller to the ground, including the UAV's AHRS information, navigation positioning position information, altitude information, mode and mission information. This data link has a large amount of data, a high update rate, and low real-time requirements;

[0031] Link 4, pod control command: This link is the control command of the ground station or remote control to the pod. The control level of the ground station is higher than that of the remote control. The remote control can control the pod only when the ground station does not control the pod. The data volume of this link is very low, the update rate is high, and the real-time requirement is high;

[0032] Link 5, ground station control instructions: The data of this link includes the flight controller control instructions of link 2 and the pod control instructions of link 4. This link has a large amount of data, a low update rate, and a high real-time requirement;

[0033] Link 6, UAV feedback information: This link is exactly the same as the information returned by the flight controller in Link 3. After receiving the information, the ground station decodes it and feeds back the UAV status information on the ground station software. This data link has a large amount of data, a high update rate, and low real-time requirements.

[0034] Furthermore, the data link frame format: a complete frame of data is divided into 7 parts: frame header, receiver ID, data category identifier, frame length, data content, CRC check bit, and end flag bit. The receiver ID is used to quickly locate the receiver of the data frame. The power UAV control board does not need to fully parse each frame of data to know how to process the data frame; the data category identifier indicates the content of the frame data, which is convenient for the receiver to parse the data. The data category identifier uses one byte to store and provides 256 different identifiers. During program debugging and system upgrades, the identifier can also be expanded;

[0035] Protocol communication mode: quasi-master-slave communication mode is adopted, the power UAV control board is the master, the flight controller is the slave, and the power UAV control board and the flight controller communicate one-to-one:

[0036] 1) Establish connection: The power UAV control board sends a connection command to the flight controller. The flight controller responds with ACK after receiving it, indicating that the connection is successful. Other communication modulations must be valid only after the connection is successful;

[0037] 2) Data telemetry: After the flight controller is connected, it will automatically send telemetry data packets to the power UAV control board at a fixed time. The default sending frequency is 2Hz. If the power UAV control board does not receive telemetry data within 5s, it will stop the communication request with the flight controller and the program will mark the communication disconnected.

[0038] 3) Heartbeat communication: During the connection of the power UAV control board, the heartbeat command is sent to the flight controller regularly during the interval of telemetry data, with a sending frequency of 1Hz. If the flight controller does not receive the heartbeat within 5s, it will automatically stop sending telemetry data, and the program will mark the communication disconnected;

[0039] 4) Session response: For all communication sessions that require flight controller feedback data, that is, a complete closed-loop response communication, it is initiated by the power UAV control board, and the flight controller responds after receiving it; during the session, the flight controller automatically suspends the sending of telemetry data to respond to the session to avoid data blocking;

[0040] 5) Disconnection: The power UAV control board sends a disconnect command to the flight controller. After receiving it, the flight controller immediately stops sending telemetry data packets at regular intervals, and then responds with ACK, indicating that the disconnection is successful.

[0041] Further, CUBK modulation:

[0042] 1) Receive modulation: Use CUBK to process the serial port message. First, configure the serial port to idle interrupt mode and enable CUBK reception. At the same time, set the receive buffer and initialize CUBK. When external data is received, CUBK stores the data to the specified address in the background. When the entire frame of data is received, a serial port idle interrupt is generated. In this interrupt, the CPU extracts the data frame from the address and performs further processing. At this time, the CUBK_GetCurrDataCounter() function is used to calculate the total length of the data frame for data processing. When defining the data buffer, it should be greater than the length of the longest single frame to avoid data overflow and loop overwriting;

[0043] 2) Send modulation: first write data to the data cache, and then send CUBK. CUBK sends the cached data outward through the serial port. When the sending is completed, a CUBK sending completion interrupt is generated, and the interrupt service subroutine is entered. In the interrupt service subroutine, the interrupt flag is cleared and the CUBK sending is turned off. At the same time, a software flag is set to the main program to prompt the main program that the data sending is completed, so that the main program can do the next step of processing.

[0044] Further, uplink control data:

[0045] 1) Data request instructions: Flight control instructions include changing flight control mode settings, pointing flight, waypoint planning, and data request instructions;

[0046] Data request instruction: A data request instruction is provided in the protocol. When the ground station requests to refresh the data or specify a parameter indicator to be observed, the ground station directly issues a data request to request the flight controller to feedback specific data.

[0047] In the data packet format frame of the data request instruction, RX is the ID of the data request target, 0x01 is the flight controller, and 0x03 is the power UAV control board;

[0048] The corresponding relationship of data request types is: 0x00 requests voltage, flight mode UAV parameters, 0x01 requests AHRS attitude information, 0x02 requests navigation positioning information, 0x03 requests flight controller output value information, Ox04 remote control input monitoring;

[0049] 2) Mode setting and point-to-point flight: Point-to-point flight means that you can command the UAV to fly to a point by specifying a point on the ground station map page. The implementation of point-to-point flight is accompanied by the switching of flight modes. The data frame transmits these two data at the same time. If only mode switching is required, the coordinate information of the point-to-point flight is the default value;

[0050] The data packet format for mode setting and pointing flight is:

[0051] 0x55,0x02,C,L, <1> , <2> , <3> , <4> , <5> ,CRC,Ox51

[0052] <1> 4Byte target point longitude, double type, magnified 1E7 times, transmitted in S32, default value is four 0xFF;

[0053] <2> 4Byte target point latitude, double type, magnified 1E7 times, transmitted in S32, default value is four 0xFF;

[0054] <3> 2Byte target point height, float type, magnified 10 times S16 transmission, unit meter, default value 0xFFFF;

[0055] <4> 1 Byte, flight mode switch, 0x01 manual, 0x02 stabilization, 0x03 self-driving, 0x04 return.

[0056] 3) Waypoint planning: Plan the UAV's flight mission on the ground station, transmit the set waypoints to the UAV, and wait for the trigger command. After the automatic route is triggered, the UAV can automatically fly according to the predetermined route;

[0057] The data packet format of waypoint planning is:

[0058] 0x55,0x02,C,L, <1> , <2> , <3> , <4> , <5> , <6> , <7> , <8> , <9> , <10> ,CRC,0x51;

[0059] <1> 1Byte waypoint number, range 1-255;

[0060] <2> 1 Byte waypoint attribute, 10 represents a normal waypoint, 20 represents a hovering point, 30 represents a landing point, and the others are reserved;

[0061] <3> 4Byte waypoint longitude, double type amplified 1E7 times and transmitted in S32;

[0062] <4> 4Byte waypoint latitude, double type amplified 1E7 times and transmitted in S32;

[0063] <5> 2Byte waypoint altitude, float type, magnified 10 times and transmitted in S16, unit: meter;

[0064] <6> 1Byte flight speed, float type is magnified 10 times and transmitted in S8, unit is meter per second;

[0065] <7> 1Byte head pointing, U8 type, unit degree;

[0066] <8> 1Byte dwell time, U8 type, 0-255, unit: seconds;

[0067] <9> 1Byte waypoint mission, flight controller advanced mission action, reserved;

[0068] <10> 1Byte next waypoint, the number of the next waypoint. When it is 0x00, it means the last waypoint has been transmitted.

[0069] 4) Pod control command: After the power UAV control board classifies the uplink control data, it is directly sent to the pod, that is, the data frame with the receiver ID of 0x03 can be forwarded to the pod without any processing; its data packet format is:

[0070] 0x55,0x03,C,L, <1> , <2> , <3> , <4> , <5> ,CRC,Ox51;

[0071] <1> 2-byte pitch control value, 1000 when stationary, 0-2000 corresponds to the maximum rate of downward and upward rotation respectively;

[0072] <2> 2-Byte direction control value, 1000 when stationary, 0-2000 corresponding to maximum speed left and right turn respectively;

[0073] <3> 2-byte focus control value, 1000 when stationary, 0-2000 corresponds to the maximum rate of near focus and far focus respectively, and when it is greater than 2010, it is auto focus;

[0074] <4> 1 Byte video recording and photo taking flag, 0xF* for video recording, 0xF for photo taking (* is any value);

[0075] <5> 1Byte PTZ centering flag, 0x00 for centering, other values ​​are ignored;

[0076] The pod control commands from the remote controller are packaged and sent out by the power UAV control board.

[0077] Further, downlink telemetry data:

[0078] 1) Power UAV parameters: UAV parameters include flight controller alarm information, UAV battery voltage, flight mode, flight time, and flight distance information; the UAV parameter data packet format is:

[0079] 0x55, 0x01, C, L, <1> , <2> , <3> , <4> , <5> ,CRC,Ox51;

[0080] <1> 1Byte alarm code, abnormal information mark during flight, reserved for flight control;

[0081] <2> 2Byte battery voltage, the power battery voltage value is amplified 100 times and transmitted via U16;

[0082] <3> 1Byte flight mode, the current flight mode status of the drone;

[0083] <4> 2Byte: time from takeoff to the present, 0-65535, in seconds;

[0084] <5> 2Byte distance from the take-off point, 0-65535, unit: meter;

[0085] 2) Attitude information protocol: UAV attitude, speed, and altitude information, which are obtained by filtering, transforming, integrating, and solving the original values ​​of the airborne strapdown inertial navigation device;

[0086] The format of the attitude information data packet is:

[0087] 0x55, 0x01, C, L, <1> , <2> , <3> , <4> , <5> , <6> , <7> , CRC, 0x51

[0088] <1> 1Byte roll angle, S8 type, unit degree

[0089] <2> 1Byte pitch angle, S8 type, unit degree

[0090] <3> 1Byte yaw angle, US type, unit degree

[0091] <4> 1Byte eastbound speed, S8 type, unit: meter per second

[0092] <5> 1 Byte northbound speed, S8 type, unit: meter per second

[0093] <6> 1Byte vertical speed, S8 type, unit: meter per second

[0094] <7> 2Byte relative to the take-off point height, float type amplified 10 times and transmitted in S16, unit: meter;

[0095] 3) Flight controller output value: The high level time of the control signal PWM output by the flight control to the four motors. The lowest throttle position is 1000 and the highest throttle position is 2000. This value is monitored to evaluate the flight performance of the UAV;

[0096] The protocol provides eight channels of data bits, supporting up to 8-axis aircraft. In the UAV communication interactive link system, only four are used, and the other bits are reserved;

[0097] The flight controller output value data packet format is:

[0098] 0x55, 0x01, C, L, <1> , <2> , <3> , <4> , <5> , <6> , <7> , <8> , CRC, 0x51;

[0099] <1> 2Byte motor output 1 channel value, 1000-2000, transmitted in U16;

[0100] <2> 2Byte motor output 2 channel value, 1000-2000, transmitted in U16;

[0101] <3> 2Byte motor output 3 channel value, 1000-2000, transmitted in U16;

[0102] <4> 2Byte motor output 4 channel value, 1000-2000, transmitted in U16;

[0103] <5> 2Byte motor output 5 channel value, reserved, all set to 0x00;

[0104] <6> 2Byte motor output 6 channel value, reserved, all set to 0x00;

[0105] <7> 2Byte motor output 7 channel value, reserved, all set to 0x00;

[0106] <8> 2Byte motor output 8 channel value, reserved, all set to 0x00.

[0107] 4) Remote control input value monitoring protocol: The K-DEF remote control control signal monitored by the power UAV control board is received and parsed by the power UAV control board and used to control the pod. At the same time, when the ground station requests monitoring data, the power UAV control board encapsulates it into a data frame and transmits it back to the ground station. The ground station can then monitor the input signal of the remote control;

[0108] The format of the remote control input value monitoring data packet is:

[0109] 0x55, 0x01, C, L, <1> , <2> , <3> , <4> , <5> , <6> , <7> , <8> , CRC, 0x51;

[0110] <1> 2Byte aileron channel value, 0-2000, transmitted in U16;

[0111] <2> 2Byte up / down channel value, 0-2000, transmitted in U16;

[0112] <3> 2Byte throttle channel value, 0-2000, transmitted in U16;

[0113] <4> 2Byte direction channel value, 0-2000, transmitted in U16;

[0114] <5> 2ByteCH5 (mode switching) channel value, 0-2000, transmitted in U16;

[0115] <6> 2ByteoCH6 (AUX1) channel value, 0-2000, transmitted in U16;

[0116] <7> 2ByteCH7(AUX2) channel value, 0-2000, transmitted in U16;

[0117] <8> 2ByteCH8(AUX3) channel value, 0-2000, transmitted in U16.

[0118] Furthermore, the remote control protocol: the remote control uses a FRSKY remote control with 16 channels, which cooperates with the L9R receiver to output the K-DEF control protocol; the K-DEF physical interface is a TTL level serial port, and the logic level is opposite to the TTL level. When physically connected, an inverter is installed at the front end to reverse the level and the serial port can be used to read data. The serial port configuration during communication is a baud rate of 100kbps, 8 data bits, even parity, 2 stop bits, no flow control, 25 bytes per frame, and the data bit transmission of the protocol sets the analog quantity of 16 channels. Each channel is represented by 11 binary numbers, so there are 22 bytes in total. The value of each channel ranges from 0 to 2047, of which channels 1-5 control the attitude and mode of the UAV, channel 6 controls the camera to take pictures, record videos, auto focus and return to the center, and channels 7 and 8 control the pan / tilt to move up, down, left and right;

[0119] When the electric UAV control board does not receive control instructions from the ground station to the pod, it takes the remote control value every 15ms, maps it into the pod control instruction through calculation, encapsulates it into a pod control frame and sends it to the pod. When the electric UAV control board receives control instructions from the ground station to the pod, the remote control of the pod is blocked. Only after the local control instruction to the pod disappears for 2 seconds, the remote control continues to control the pod, thereby realizing the distinction of control authority.

[0120] Compared with the prior art, the innovations and advantages of this application are:

[0121] First, this application designs and implements a data link system solution for power inspection UAVs that meets the requirements of national standards. This solution can fully meet the requirements of the State Grid for the communication and interactive link system of power inspection UAVs. Based on the structure and mechanism of the UAV data link, a data link solution with high reliability, good security, high integration and long transmission distance is proposed. The design and construction of the hardware solution of the power inspection UAV data link system have been completed. Taking into account the various characteristics of each hardware device, the data link system hardware equipment suitable for the power inspection UAV system has been designed, and its characteristics, configuration methods, and installation methods have been described in detail. The anti-interference design of the power UAV control board is proposed. According to the UAV data link system, a complete set of communication protocols is designed to meet the data transmission application of the power inspection UAV, and data blocking is demonstrated. Through design and calculation, the data flow is reasonably arranged to prevent the occurrence of data blocking. A test method for the frame loss rate of the power inspection UAV communication and interactive link system is designed, and the performance of this application is tested according to the test method. The various parameter indicators of the extreme communication distance of this communication and interactive link system are clarified, which is of great significance for guiding the actual work of the power inspection UAV.

[0122] Second, this application proposes the overall design of the UAV communication interaction link system, through the power inspection UAV system architecture, UAV platform, inspection system ground station system, inspection UAV data link equipment, and power UAV control board; build the design of the power inspection UAV data link system hardware, make specific improvements to the UAV communication interaction link system, optimize the hardware architecture, configuration mode, and installation method, and propose an electromagnetic interference-resistant UAV communication link based on the power UAV control board to achieve high-quality interaction over long distances. It solves the problems of complex use environment, large amount of transmitted data, large environmental interference, and difficult to guarantee communication distance of the power inspection UAV data link system. The actual communication distance in use is greater than 2 kilometers. When the distance increases, the communication quality remains stable, meeting the requirements of power inspection.

[0123] Third, this application proposes a UAV communication interaction protocol for power inspection. Through the design of UAV communication interaction data link setting, data link frame format, protocol communication mode, and link congestion control, the UAV communication interaction is divided into 6 data according to the physical connection, and the data blocking is demonstrated and calculated, and the data flow is arranged to prevent data blocking; the control delay problem is solved, and the problem that the UAV crashes into obstacles, especially wires, due to the high control delay caused by the lack of avoidance. The power inspection UAV system can respond quickly to the control signal on the ground, and the control delay is less than 15ms. Especially when the amount of transmitted data is large and the types of data are many, the delay is still effectively controlled to prevent data blocking.

[0124] Fourth, the present application proposes a UAV communication interaction protocol modulation method, through CUBK modulation, uplink control data, downlink telemetry data, remote control protocol; data security is guaranteed to prevent others from maliciously monitoring data and illegally accessing the UAV system, or malicious operations that pose a greater threat to power grid security; the communication interaction link data bandwidth is improved, and long-term long-distance protection includes remote control data, telemetry data, image data and other data volumes and data types of power inspection UAV communication data transmission; overcome the difficulties of strong electromagnetic interference and electrostatic interference in the power inspection environment, solve the problem that the carrier signal cannot be identified, interferes with the data link system, and affects the communication quality. Compared with the prior art method, it has the advantages of high integration, light weight, small size, long communication distance, and good reliability, and has great practical significance for the long-distance data transmission of the power inspection UAV system. BRIEF DESCRIPTION OF THE DRAWINGS

[0125] Figure 1 It is the link and port allocation diagram of the UAV communication interaction link hardware equipment.

[0126] Figure 2 This is a schematic diagram of serial port message reception processing using the CUBK method.

[0127] Figure 3 This is a schematic diagram of the CUBK method for sending serial port message modulation processing.

[0128] Figure 4 This is a diagram of the data packet format of the data request instruction.

[0129] Figure 5 This is a schematic diagram of the uplink packet loss rate when the UAV is 2 km away from the ground station.

[0130] Figure 6 This is a schematic diagram of the downlink packet loss rate when the UAV is 2 km away from the ground station.

[0131] Figure 7 This is a schematic diagram of the uplink packet loss rate when the UAV is 5 km away from the ground station.

[0132] Figure 8 This is a schematic diagram of the downlink packet loss rate when the UAV is 5 km away from the ground station.

[0133] Fig. 9 This is a diagram of the UAV experimental pod control function verification process. DETAILED DESCRIPTION

[0134] Below, in conjunction with the accompanying drawings, the technical solution of the long-distance communication interactive link system of the power inspection drone provided in the present application is further described so that technicians in this field can better understand the present application and implement it.

[0135] With the rapid development of integrated circuits, automatic control and communication technologies, the UAV industry has begun to grow explosively. Industrial UAVs, represented by power inspection drones, have a large number of application needs. As an important part of the UAV system, the data link system is responsible for the information exchange between the UAV and the ground control. How to design a data link system suitable for power inspection drones has become an urgent problem to be solved. This application designs a UAV data link system with high integration, small size, light weight, long communication distance, good reliability, and meets the national standard inspection standards for power inspection drones.

[0136] This application conducts an in-depth study on the structure and mechanism of the UAV data link system, analyzes the principles and characteristics of various types of systems in the current existing technology, integrates the advantages of various solutions, and proposes a data link design solution with high reliability, good security, high integration and long transmission distance.

[0137] Firstly, the hardware solution of the data link system of the power inspection UAV is designed and built. Taking into account the characteristics of each hardware device, XTEND is used as the data transmission device and FHD10OHT is used as the image transmission device. Its characteristics, configuration and installation methods are described in detail.

[0138] A complete set of communication protocols was designed based on the data link system of the power inspection drone, which can meet the data transmission application of the power inspection drone. A set of inspection methods for the performance of the communication interactive link system of the power inspection drone was designed, and the performance of this system was inspected according to the inspection method, and the various parameter indicators of this communication interactive link system were clarified.

[0139] This application proposes a data link solution that meets the relevant national standards. Compared with traditional methods, it has the advantages of high integration, light weight, small size, long communication distance and good reliability, and has great practical significance for power inspection drone systems.

[0140] 1. Overall design of UAV communication interactive link system

[0141] The power inspection UAV communication interactive link system is connected and interacted with other systems. In order to better design the UAV communication interactive link system, it is necessary to analyze the terminal equipment of the UAV communication interactive link system and design the UAV communication interactive link system specifically according to the different characteristics of the terminal equipment and the data it transmits. The links and port allocations of all hardware devices are as follows: Figure 1 shown.

[0142] (I) Power inspection drone system architecture

[0143] The power inspection UAV system is divided into two parts: the mission carrier and the ground station. The mission carrier is a multi-rotor UAV, and the UAV platform includes a flight control system and a pod system. The mission payload is a visible light or infrared pod that takes photos and records videos, and the video and UAV telemetry information are transmitted back to the ground station in real time.

[0144] The ground station consists of a receiving station, a portable proportional remote control and an industrial-grade computer. The receiving station is composed of a data transmission, a WIFI module and an image transmission receiving end, and the packaging is convenient for operation. The ground station computer monitors the real-time data of the mission carrier and the returned video information, and at the same time controls and modulates all the mission carriers. The remote control controls the flight attitude of the UAV and controls the pod to take pictures, record videos and focus.

[0145] The design block diagram of the communication interaction link system is as follows: Figure 1 As shown. Three wireless links are used for data transmission. The frequency of each link is different to avoid co-frequency interference. At the same time, all three links use digital signal transmission. The links complement and backup each other to ensure the safety of the power inspection drone system. At the same time, the structure of each link is clear, the equipment is simplified to the minimum, and the impact of equipment failure is reduced.

[0146] 2. UAV Platform

[0147] (1) Flight controller system

[0148] The flight controller system is composed of computing chips, sensors and other peripheral circuits. The sensors include: navigation and positioning module, electronic magnetic compass, barometric altimeter, three-axis accelerometer and three-axis gyroscope. The flight controller system obtains the attitude, speed, altitude and navigation and positioning information of the UAV by collecting data from various sensors, and sends out control signals by solving and processing these information to maintain the self-stabilizing flight of the UAV and execute mission actions. The external interface of the flight controller system adopts UARTR serial port with a baud rate of 115200Kbps. The transmitted data includes the solved UAV attitude information and navigation and positioning information, which are all transmitted to the outside through the serial port, and at the same time receive control commands from the ground.

[0149] (2) Infrared Pod

[0150] The pod is an important mission payload of the power inspection UAV. It collects images of the target location. The pod consists of a gimbal and a camera. The camera captures infrared images and transmits them to the image transmission module through the HDMI interface. The gimbal system has a built-in three-axis gyroscope, accelerometer chip and magnetic compass chip. The main controller controls the direction of the camera by continuously adjusting the three-axis brushless motor to offset the deflection and jitter of the UAV, making the camera system image stable. The main controller communicates with the power UAV control board through the serial port, receives control instructions, and controls the camera to focus and take pictures.

[0151] (III) Inspection system ground station system

[0152] The ground station of the inspection system is the command system of the power inspection drone. The inspection ground station system consists of a remote control, a ground station computer, and a receiving station.

[0153] (1) Remote control

[0154] It uses a 16-channel FRSKY remote control, works in the 2.4G frequency band, uses ACCST frequency hopping, achieves hundreds of continuous frequency hopping per second, greatly reduces signal conflicts and interruptions, has an omnidirectional transmission power of 100mW, and is paired with an L9R long-distance receiver, with a practical control distance of 5Km.

[0155] (2) Receiving station

[0156] The receiving station uses a box to encapsulate the wireless receiving device, and uses a tripod or other support to lift the box off the ground to improve the signal reception effect. The receiving station is composed of a data transmission, image transmission receiver, a WIFI module and a power supply supporting module. The data transmission module is paired with the airborne data transmission module for duplex communication. The data transmission module is connected to the serial port of the WIFI module through the serial port for access by the ground station computer equipment through WIFI. The image transmission receiver receives the real-time image sent back by the image transmission transmitter on the UAV, and is connected to the WIFI module through the network interface. The ground station computer equipment accesses the returned image through the RTSP protocol and plays it out after decoding.

[0157] (IV) Inspection UAV data link equipment

[0158] The data link equipment is the link between UAV and ground information exchange and the carrier of data transmission. The data link equipment consists of image transmission equipment, data transmission equipment, power UAV control panel and remote control equipment.

[0159] 1. Image transmission system

[0160] The image transmission system completes the image transmission part of the UAV communication interactive link. It uses an image transmission radio based on COFDM (Coded Orthogonal Frequency Division Multiplexing) technology to convert high-speed data streams into serial-to-parallel and distribute them to several sub-channels with lower transmission rates, thereby achieving good shielding against noise and interference. It can also stably transmit image and audio signals under high-speed movement and multi-path interference. It is particularly suitable for long-distance image transmission in complex terrain and beyond visual range.

[0161] 2. Digital transmission system

[0162] The data transmission module adopts transparent transmission, that is, the input data and the output data are exactly the same, and the data interface is a serial port. In order to reduce the burden on the UAV, the data transmission module is as small as possible, as light as possible, and consumes as little power as possible. The communication distance is as far as possible, while ensuring a transmission distance of at least 2 kilometers.

[0163] (V) Power UAV control panel

[0164] 1. Main controller

[0165] The electric UAV control board has at least four serial ports for other devices to access. The STM32F103RCT6 chip is used as the main chip of the electric UAV control board. The chip configuration can be easily completed by calling the function of the library file. In order to cooperate with other airborne devices of the D4A UAV, the electric UAV control board uses the serial port to communicate directly with other devices. Serial port 1 is connected to the flight controller with a baud rate of 115200Kbps, and the frame format follows the flight controller communication interaction protocol. Serial port 2 is connected to the pod with a baud rate of 9600Kbps. Serial port 3 is connected to the data transmission with a baud rate of 115200Kbps, using a custom communication interaction protocol. Serial port 4 is connected to the receiver with a baud rate of 100Kbps, receiving K-DEF instructions. The serial port uses CUBK for transceiver modulation, and a data path between RAM and I / 0 devices is opened in hardware.

[0166] 2. Signal isolation design

[0167] A bidirectional level converter or a universal level driver is added in the middle of the signal line to isolate the signal and increase the withstand voltage and driving ability. The A port and the B port are set. When the A port inputs the signal, the input voltage is 1.2V to 3.6V, and when the B port inputs the signal, the input voltage is 1.65V to 5.5V. When the output enable is turned off, all the output ports at the B end are in a high impedance state. For the signal entering the A port, the static electricity is isolated. The A port prevents 2000V static electricity generated by the human body, 150V static electricity generated by machinery, and 1kV static electricity caused by charging equipment. When the signal is input from the B port, a contact discharge of up to 8kV is achieved, and the output voltage is increased by 0.5V on the basis of VCC, and the driving capacity reaches 50mA of current, which improves the signal quality and driving force, and prevents the MCU from burning when a large current appears at the input end.

[0168] 3. Anti-electromagnetic interference design

[0169] The power supply signal is filtered to eliminate interference signals. The filter device used is NFM18PC104, which has an overcurrent capacity of 2A and a withstand voltage of up to 16V. It can effectively suppress high-frequency harmonic signals and prevent high-frequency harmonic signals from interfering with other devices.

[0170] Ferrite beads are used for filtering at the signal port to prevent electromagnetic interference signals from entering the circuit through spatial coupling. Low-frequency signals pass directly through the inductor without obvious attenuation. High-frequency signals cannot pass through the inductor, and will generate heat energy when passing through the resistor, resulting in greater attenuation. When the frequency of the noise signal gradually increases, its inductive reactance also gradually increases, and the resistance value first increases and then decreases. These two changes cooperate with each other to improve the filtering characteristics. Magnetic beads are used on signal lines to filter interference signals and improve communication quality.

[0171] 2. Power Inspection UAV Communication Interaction Protocol

[0172] (I) UAV communication interactive data link settings

[0173] According to the physical connection, UAV communication interaction is divided into 6 data links:

[0174] Link 1, remote control command: This link is the SBUS control command issued by the remote control receiver. The effective information is the control information of the remote control receiver on the pod, that is, controlling the pod to move up, down, left, and right, and controlling the camera to take pictures and record videos. This link has low data volume, fast update rate, and high real-time requirements;

[0175] Link 2, flight controller control instructions: This link transmits the control instructions from the ground station to the flight controller, including changing the flight mode, pointing the flight, and setting parameter information. This link has a large amount of data, a very low update rate, and low real-time requirements;

[0176] Link 3, flight controller feedback information: This link is the data information sent back by the flight controller to the ground, including the UAV's AHRS information, navigation positioning position information, altitude information, mode and mission information. This data link has a large amount of data, a high update rate, and low real-time requirements;

[0177] Link 4, pod control command: This link is the control command of the ground station or remote control to the pod. The control level of the ground station is higher than that of the remote control. The remote control can control the pod only when the ground station does not control the pod. The data volume of this link is very low, the update rate is high, and the real-time requirement is high;

[0178] Link 5, ground station control instructions: The data of this link includes the flight controller control instructions of link 2 and the pod control instructions of link 4. This link has a large amount of data, a low update rate, and a high real-time requirement;

[0179] Link 6, UAV feedback information: This link is exactly the same as the information returned by the flight controller in Link 3. After receiving the information, the ground station decodes it and feeds back the UAV status information on the ground station software. This data link has a large amount of data, a high update rate, and low real-time requirements.

[0180] (II) Data link frame format

[0181] A complete frame of data is divided into 7 parts: frame header, receiver ID, data category identifier, frame length, data content, CRC check bit, and end flag bit. The receiver ID is used to quickly locate the receiver of the data frame. The power UAV control board does not have to fully parse each frame of data to know how to process the data frame, thereby improving the efficiency and accuracy of the power UAV control board's communication control.

[0182] The data category identifier indicates the content of the frame data, which makes it easier for the receiver to parse the data. The data category identifier uses one byte for storage and provides 256 different identifiers. During program debugging and system upgrades, the identifier can also be expanded to facilitate system expansion.

[0183] (III) Protocol communication mode

[0184] A quasi-master-slave communication mode is adopted, with the electric UAV control board as the master and the flight controller as the slave, and the electric UAV control board and the flight controller communicate one-to-one.

[0185] 1) Establish connection: The power UAV control board sends a connection command to the flight controller. The flight controller responds with ACK after receiving it, indicating that the connection is successful. Other communication modulations must be valid only after the connection is successful;

[0186] 2) Data telemetry: After the flight controller is connected, it will automatically send telemetry data packets to the power UAV control board at a fixed time. The default sending frequency is 2Hz. If the power UAV control board does not receive telemetry data within 5s, it will stop the communication request with the flight controller and the program will mark the communication disconnected.

[0187] 3) Heartbeat communication: During the connection of the power UAV control board, the heartbeat command is sent to the flight controller regularly during the interval of telemetry data, with a sending frequency of 1Hz. If the flight controller does not receive the heartbeat within 5s, it will automatically stop sending telemetry data, and the program will mark the communication disconnected;

[0188] 4) Session response: For all communication sessions that require flight controller feedback data, that is, a complete closed-loop response communication, it is initiated by the power UAV control board, and the flight controller responds after receiving it; during the session, the flight controller automatically suspends the sending of telemetry data to respond to the session to avoid data blocking;

[0189] 5) Disconnection: The power UAV control board sends a disconnect command to the flight controller. After receiving it, the flight controller immediately stops sending telemetry data packets at regular intervals, and then responds with ACK, indicating that the disconnection is successful.

[0190] (IV) Link congestion control

[0191] 1. Discarding erroneous data: No retransmission request is made for erroneous data to ensure that the congestion of the data link does not enter a vicious cycle. The uplink control data requires the delay to be as low as possible, and the erroneous data is discarded to reduce the data delay as much as possible. The downlink telemetry information does not require high real-time data. After the erroneous data is discarded, it will be updated until the next data request to meet the design requirements;

[0192] 2. Throughput control: Control the total amount of data flowing into the wireless link. In a unit of time, the total amount of wireless link transmission must be lower than its link bandwidth. The timing of the communication protocol is strictly controlled to ensure that the amount of data flowing into the data transmission link is strictly lower than its transmission capacity to prevent congestion.

[0193] 3. Data diversion: The data link system of the power inspection drone uses a separated link method to separate high-speed, low-latency data and low-speed, large-volume data, so that the data type of each link is as uniform as possible, avoiding conflicts between different types of data requests and preventing congestion.

[0194] 3. Modulation Method of UAV Communication Interaction Protocol

[0195] (I) CUBK modulation

[0196] In this application, the electric UAV control board uses 4 serial ports for data communication. In traditional serial port communication, serial port receiving and sending interruptions are generally used to read and send serial port data. This approach is simple and convenient in program writing, but the efficiency is extremely low. The system cannot handle other events when sending and receiving data. Frequent communication will generate a large number of serial port interruptions, which can easily lead to data blocking and even system paralysis.

[0197] 1. Receive modulation

[0198] This application uses the CUBK method to process serial port messages. The specific process is as follows: Figure 2 As shown. First, configure the serial port to idle interrupt mode and enable CUBK reception, set the receiving buffer and initialize CUBK at the same time. When external data is received, CUBK stores the data to the specified address in the background. When the entire frame of data is received, a serial port idle interrupt is generated. In this interrupt, the CPU extracts the data frame from the address and performs further processing. At this time, the CUBK_GetCurrDataCounter() function is used to calculate the total length of this data frame to facilitate data processing. When defining the data buffer, it should be greater than the length of the longest single frame to avoid data overflow and loop overwriting.

[0199] 2. Send modulation

[0200] First, write data to the data cache, and then send CUBK. CUBK sends the cached data out through the serial port. When the sending is completed, a CUBK sending completion interrupt is generated, and the interrupt service subroutine is entered. In the interrupt service subroutine, the interrupt flag is cleared and CUBK sending is turned off. At the same time, a software flag is set to the main program to prompt the main program that the data has been sent, so that the main program can do the next step. The software flow is as follows Figure 3 shown.

[0201] (II) Uplink control data

[0202] The uplink control data is the control instructions sent by the ground station to the flight controller and pod. The instructions are divided into pod control instructions and flight control control instructions and data requests.

[0203] 1. Data request instructions

[0204] Flight control commands include changing flight control mode settings, pointing flight, waypoint planning, and data request commands.

[0205] Data request instruction: A data request instruction is provided in the protocol. When the ground station requests to refresh the data or specify a parameter indicator to be observed, the ground station directly issues a data request to request the flight controller to feedback specific data.

[0206] The data packet format of the data request instruction is as follows: Figure 4 In this frame, RX is the ID of the data request target, 0x01 is the flight controller, and 0x03 is the power UAV control board.

[0207] The corresponding relationship of data request types is: 0x00 requests voltage, flight mode UAV parameters, 0x01 requests AHRS attitude information, 0x02 requests navigation positioning information, 0x03 requests flight controller output value information, Ox04 remote control input monitoring (this value needs to be requested from the power UAV control board).

[0208] 2. Mode setting and pointing flight

[0209] Point-to-point flight is to designate a point on the ground station map page at random, and then command the UAV to fly to this point. The realization of point-to-point flight must be accompanied by the switching of flight modes. This data frame completes the transmission of these two data at the same time. If only the mode switching is required, the coordinate information of the point-to-point flight is the default value;

[0210] The data packet format for mode setting and pointing flight is:

[0211] 0x55,0x02,C,L, <1> , <2> , <3> , <4> , <5> ,CRC,Ox51

[0212] <1> 4Byte target point longitude, double type, magnified 1E7 times, transmitted in S32, default value is four 0xFF;

[0213] <2> 4Byte target point latitude, double type, magnified 1E7 times, transmitted in S32, default value is four 0xFF;

[0214] <3> 2Byte target point height, float type, magnified 10 times S16 transmission, unit meter, default value 0xFFFF;

[0215] <4> 1 Byte, flight mode switch, 0x01 manual, 0x02 stabilization, 0x03 self-driving, 0x04 return.

[0216] 3. Waypoint planning

[0217] Waypoint planning is to plan the flight mission of the UAV on the ground station. After the set waypoints are transmitted to the UAV, it waits for the trigger command. After the automatic route is triggered, the UAV can automatically fly according to the predetermined route. The data packet format of waypoint planning is:

[0218] 0x55,0x02,C,L, <1> , <2> , <3> , <4> , <5> , <6> , <7> , <8> , <9> , <10> ,CRC,0x51;

[0219] <1> 1Byte waypoint number, range 1-255;

[0220] <2> 1 Byte waypoint attribute, 10 represents a normal waypoint, 20 represents a hovering point, 30 represents a landing point, and the others are reserved;

[0221] <3> 4Byte waypoint longitude, double type amplified 1E7 times and transmitted in S32;

[0222] <4> 4Byte waypoint latitude, double type amplified 1E7 times and transmitted in S32;

[0223] <5> 2Byte waypoint altitude, float type, magnified 10 times and transmitted in S16, unit: meter;

[0224] <6> 1Byte flight speed, float type is magnified 10 times and transmitted in S8, unit is meter per second;

[0225] <7> 1Byte nose pointing, U8 type, unit degree;

[0226] <8> 1Byte dwell time, U8 type, 0-255, unit: seconds;

[0227] <9> 1Byte waypoint mission, flight controller advanced mission action, reserved;

[0228] <10> 1Byte next waypoint, the number of the next waypoint. When it is 0x00, it means the last waypoint has been transmitted.

[0229] 4. Pod control instructions

[0230] The pod control command is sent directly to the pod by the power UAV control board after classifying the uplink control data, that is, the data frame with the receiver ID of 0x03 can be forwarded to the pod without any processing. The data packet format is:

[0231] 0x55,0x03,C,L, <1> , <2> , <3> , <4> , <5> ,CRC,Ox51;

[0232] <1> 2-byte pitch control value, 1000 when stationary, 0-2000 corresponds to the maximum rate of downward and upward rotation respectively;

[0233] <2> 2-Byte direction control value, 1000 when stationary, 0-2000 corresponding to maximum speed left and right turn respectively;

[0234] <3> 2-byte focus control value, 1000 when stationary, 0-2000 corresponds to the maximum rate of near focus and far focus respectively, and when it is greater than 2010, it is auto focus;

[0235] <4> 1 Byte video recording and photo taking flag, 0xF* for video recording, 0xF for photo taking (* is any value);

[0236] <5> 1Byte PTZ centering flag, 0x00 for centering, other values ​​are ignored;

[0237] The pod control commands from the remote controller are packaged and sent out by the power UAV control board.

[0238] 3. Downlink telemetry data

[0239] Downlink telemetry data is the feedback information transmitted by the UAV to the ground, including the battery voltage fed back by the flight controller, flight mode UAV parameters, AHRS heading information, navigation positioning information, flight controller output value, and remote control input value.

[0240] 1. Power UAV parameters

[0241] UAV parameters include flight controller alarm information, UAV battery voltage, flight mode, flight time, and flight distance. The UAV parameter data packet format is:

[0242] 0x55, 0x01, C, L, <1> , <2> , <3> , <4> , <5> ,CRC,Ox51;

[0243] <1> 1Byte alarm code, abnormal information mark during flight, reserved for flight control;

[0244] <2> 2Byte battery voltage, the power battery voltage value is amplified 100 times and transmitted via U16;

[0245] <3> 1Byte flight mode, the current flight mode status of the drone;

[0246] <4> 2Byte: time from takeoff to the present, 0-65535, in seconds;

[0247] <5> 2Byte distance from the take-off point, 0-65535, unit: meter.

[0248] 2. Heading Information Protocol

[0249] Attitude information refers to the attitude, speed and altitude information of the UAV. This information is obtained by filtering, transforming, integrating and solving the original values ​​of the airborne strapdown inertial navigation device. It is an important reference for the flight status of the UAV.

[0250] The format of the attitude information data packet is:

[0251] 0x55, 0x01, C, L, <1> , <2> , <3> , <4> , <5> , <6> , <7> , CRC, 0x51

[0252] <1> 1Byte roll angle, S8 type, unit degree

[0253] <2> 1Byte pitch angle, S8 type, unit degree

[0254] <3> 1Byte yaw angle, US type, unit degree

[0255] <4> 1Byte eastbound speed, S8 type, unit: meter per second

[0256] <5> 1 Byte northbound speed, S8 type, unit: meter per second

[0257] <6> 1Byte vertical speed, S8 type, unit: meter per second

[0258] <7> 2Byte relative to the take-off point height, float type, magnified 10 times, transmitted in S16, unit: meter

[0259] 3. Flight controller output value

[0260] The flight controller output value is the high level time of the control signal PWM output by the flight control to the four motors. The lowest throttle position is 1000 and the highest throttle position is 2000. This value is monitored to evaluate the flight performance of the UAV.

[0261] The protocol provides eight channels of data bits, supporting up to 8-axis aircraft. In the UAV communication interactive link system, only four are used, and the other bits are reserved.

[0262] The flight controller output value data packet format is:

[0263] 0x55, 0x01, C, L, <1> , <2> , <3> , <4> , <5> , <6> , <7> , <8> , CRC, 0x51;

[0264] <1> 2Byte motor output 1 channel value, 1000-2000, transmitted in U16;

[0265] <2> 2Byte motor output 2 channel value, 1000-2000, transmitted in U16;

[0266] <3> 2Byte motor output 3 channel value, 1000-2000, transmitted in U16;

[0267] <4> 2Byte motor output 4 channel value, 1000-2000, transmitted in U16;

[0268] <5> 2Byte motor output 5 channel value, reserved, all set to 0x00;

[0269] <6> 2Byte motor output 6 channel value, reserved, all set to 0x00;

[0270] <7> 2Byte motor output 7 channel value, reserved, all set to 0x00;

[0271] <8> 2Byte motor output 8 channel value, reserved, all set to 0x00.

[0272] 4. Remote control input value monitoring protocol

[0273] Remote control input value monitoring is the K-DEF remote control control signal monitored by the electric UAV control board. This signal is received and parsed by the electric UAV control board and used to control the pod. At the same time, when the ground station requests monitoring data, it is encapsulated into a data frame by the electric UAV control board and transmitted back to the ground station. The ground station can then monitor the input signal of the remote control.

[0274] The format of the remote control input value monitoring data packet is:

[0275] 0x55, 0x01, C, L, <1> , <2> , <3> , <4> , <5> , <6> , <7> , <8> , CRC, 0x51;

[0276] <1> 2Byte aileron channel value, 0-2000, transmitted in U16;

[0277] <2> 2Byte up / down channel value, 0-2000, transmitted in U16;

[0278] <3> 2Byte throttle channel value, 0-2000, transmitted in U16;

[0279] <4> 2Byte direction channel value, 0-2000, transmitted in U16;

[0280] <5> 2ByteCH5 (mode switching) channel value, 0-2000, transmitted in U16;

[0281] <6> 2ByteoCH6 (AUX1) channel value, 0-2000, transmitted in U16;

[0282] <7> 2ByteCH7(AUX2) channel value, 0-2000, transmitted in U16;

[0283] <8> 2ByteCH8(AUX3) channel value, 0-2000, transmitted in U16.

[0284] (IV) Remote Control Protocol

[0285] The remote controller uses a FRSKY remote controller with 16 channels, which cooperates with the L9R receiver to output the K-DEF control protocol; the K-DEF physical interface is a TTL-level serial port, and the logic level is opposite to the TTL level. When physically connected, an inverter is installed at the front end to reverse the level so that the serial port can be used to read data. The serial port configuration during communication is a baud rate of 100kbps, 8 data bits, even parity, 2 stop bits, no flow control, 25 bytes per frame, and the data bit transmission of the protocol sets the analog quantity of 16 channels. Each channel is represented by 11 binary numbers, so there are 22 bytes in total. The value of each channel ranges from 0 to 2047, of which channels 1-5 control the attitude and mode of the UAV, channel 6 controls the camera to take pictures, record videos, autofocus and return to the center, and channels 7 and 8 control the pan / tilt to move up, down, left and right.

[0286] When the electric UAV control board does not receive control instructions from the ground station to the pod, it takes the remote control value every 15ms, maps it into the pod control instruction through calculation, encapsulates it into a pod control frame and sends it to the pod. When the electric UAV control board receives control instructions from the ground station to the pod, the remote control of the pod is blocked. Only after the local control instruction to the pod disappears for 2 seconds, the remote control continues to control the pod, thereby realizing the distinction of control authority.

[0287] 4. Communication Interaction Link Performance Verification

[0288] After the communication interaction link of the power inspection UAV is built, it must undergo rigorous testing before it can be put into practical application. The testing methods include ground pull-distance tests and aerial flight tests. To ensure the safe flight of the UAV, tests are required at each stage of the design. The final test is carried out at the Beijing UHV AC Test Base.

[0289] (I) Measurement and control distance verification

[0290] The electric power inspection UAV communication interaction link system designed in this application has undergone all the tests of the Beijing High Voltage Research Institute's electric power inspection UAV acceptance test standards. Before passing the test, in order to self-verify the performance of the communication interaction link, a test method for the performance of the communication interaction link was designed.

[0291] 1. Test indicators

[0292] The inspection requirements proposed in the inspection standard clearly set the delay and communication distance for the UAV communication interactive link system. The control delay is required to be less than 20ms, because the remote control data is sent every 15ms, so the control delay is less than the 20ms required by the standard.

[0293] The communication distance is specified in the inspection standard as being greater than 2 km when flying at an altitude of 40m. When the data link frame loss rate is less than 5%, there is no obvious impact on the control of the UAV, and the communication is considered normal. During the test, the frame loss rate test is performed with 2 km, 5 km, and 10 km as the test limits, and the test results are recorded.

[0294] 2. Test methods

[0295] In order to test the frame loss rate, the ground station and the power UAV control board count the total number of uplink data frames and downlink data frames and the number of received frames in a unit time. The counting period is set to 1 minute, and the heartbeat information is continuously sent at a rate of 1Hz. The counting results are updated every minute and transmitted back to the ground station.

[0296] 3. Test frame design

[0297] The heartbeat packet is used to transmit the counting result. After receiving the data, the ground station compares the number of packets sent and received to count the packet loss rate of uplink and downlink data. There are two types of test heartbeat packets: one is the heartbeat request sent by the ground station to the power UAV control board, and the other is the heartbeat response replied by the power UAV control board.

[0298] After receiving the heartbeat packet, the power UAV control board immediately feeds back a heartbeat response frame, then clears the DATA_REC and DATA_SEN data, and starts counting immediately. The value of DATA_REC increases by 1 for each frame of data received, and the value of DATA_SEN increases by 1 for each frame of data sent. After one minute, the counting stops and the statistical value is sent to the ground station through the heartbeat packet, and a new round of counting begins.

[0299] The ground station can directly calculate the uplink data frame loss rate by comparing the DATA_REC value in the heartbeat response data received with the total number of frames sent by itself in that period. The downlink data frame loss rate can be directly calculated by comparing the DATA_SEN value with the total number of data frames received by the ground station in that period.

[0300] In the first test, the UAV was flown to a height of 40m and 2km from the ground station system. The returned images were clear and smooth, and the remote control was normal. The frame loss rate data received by the ground station was as follows: Figure 5 , Figure 6 shown.

[0301] The second test was conducted by flying the UAV to a height of 120m and 5km from the ground station system. The returned images were clear and smooth, and the remote control was normal. The frame loss rate data received by the ground station was as follows: Figure 7 , Figure 8 .

[0302] The third test flew the UAV to a hover at a height of 250m and 10km from the ground station system. The transmitted images were clear and smooth, and remote control was available.

[0303] A standard 2km pull-distance test was carried out at the Beijing UHV AC test base. During the test, the data link was stable, the return image was stable, and the remote control signal was stable. The test results of this system met the standard requirements.

[0304] (II) Radiation anti-interference performance verification

[0305] The test uses a 1KHz sine wave to modulate the interference signal, with a frequency range of 0 to 2GHz (avoiding the band used by the communication system) and a field strength of 10V / m. In an anechoic chamber, the UAV system is set up 3m away from the radiation source to interfere with the UAV. The interference signal scanning step is 1%, the single interference time is 1s, and the antenna horizontal polarization and vertical polarization are tested once each.

[0306] During the test, the data link is stable, the returned image is stable, and the remote control signal is stable. The test result of this system is Class A.

[0307] (III) Pulse and power frequency magnetic field immunity test

[0308] The test placed the UAV in the middle of the induction coil, which was connected to a pulse magnetic field generator that could generate a pulse magnetic field with a peak value of 1000A / m and a waveform of 6.4 / 16us, and an industrial frequency magnetic field with a peak value of 100A / m. Each test lasted five minutes, and the working conditions of the UAV data link were recorded.

[0309] During the test, the data link is stable, the returned image is stable, and the remote control signal is stable. The test result of this system is Class A.

[0310] (IV) Electrostatic discharge immunity test

[0311] In this test, the UAV is placed on the side of the vertical coupling plate at a distance of 0.1m. An electrostatic discharge gun is used to perform contact discharge at 10 points on the vertical coupling plate, with a discharge voltage of plus or minus 8KV. Then, a positive or minus 15KV voltage is used to perform non-contact discharge on these ten points. The working status of the UAV data link is recorded during the discharge process.

[0312] During the test, the data link is stable, the returned image is stable, and the remote control signal is stable. The test result of this system is Class A.

[0313] (V) Data link function verification

[0314] The test will have the UAV take off from a test site with power transmission lines and follow the process to complete all the functions that a data link should have, including remote control, flight mode switching, waypoint uploading, spot flying, telemetry data monitoring, and returned image viewing.

[0315] Conduct pod control function verification tests indoors to take photos and videos, and perform azimuth and zoom control on the precision black body. Fig. 9 During this test, the data link realized all the measurement and control functions required by the standard, and the test results of this system met the standard requirements.

[0316] This application is based on the State Grid power inspection UAV research and development project, and proposes a hardware design, communication protocol design and final test results of the power inspection UAV communication interaction link system. After inspection by the National Standard Grid Beijing High Voltage Research Institute, the system passed all inspection items with excellent results and has strong practical value.

Claims

1. The long-distance communication interactive link system of the power inspection drone is characterized by: The uplink sets data request instructions, mode settings and pointing flight, waypoint planning, and pod control instructions; the downlink sets power UAV parameters, attitude information protocol, flight controller output values, and remote controller input value monitoring protocol; First, the overall design of the UAV communication interaction link system, including: power inspection UAV system architecture, UAV platform, inspection system ground station system, inspection UAV data link equipment, power UAV control board; build the power inspection UAV data link system hardware, connect and interact with other systems through the communication link, make specific improvements to the UAV communication interaction link system according to the different characteristics of the terminal equipment and the data it transmits, optimize the hardware architecture, configuration mode, and installation method, and propose an anti-electromagnetic interference UAV communication link based on the power UAV control board; Second, the communication interaction protocol of the power inspection UAV includes: UAV communication interaction data link setting, data link frame format, protocol communication mode, and link congestion control; UAV communication interaction is divided into 6 data according to the physical connection, and the protocol communication adopts a quasi-master-slave communication mode. The power UAV control board is the host and the flight controller is the slave. The power UAV control board and the flight controller can communicate one-to-one, perform demonstration calculations on data blocking, arrange and set data flow, and prevent data blocking; Third, the UAV communication interaction protocol modulation method, including: CUBK modulation, uplink control data, downlink telemetry data, remote control protocol; uplink control data is the control instructions issued by the ground station to the flight controller and pod, which are divided into pod control instructions and flight control instructions and data requests; downlink telemetry data is the feedback information transmitted by the UAV end to the ground, including the battery voltage fed back by the flight controller, flight mode UAV parameters, AHRS heading information, navigation positioning information, flight controller output value, and remote control input value.

2. According to claim 1, the long-distance communication interactive link system for electric power inspection drones is characterized in that: Power inspection UAV system architecture: The power inspection UAV system is divided into two parts: the mission carrier and the ground station. The mission carrier is a multi-rotor UAV, and the UAV platform includes a flight control system and a pod system. The mission payload is a visible light or infrared pod that takes photos and records videos. The video and UAV telemetry information are transmitted back to the ground station in real time. The ground station consists of a receiving station, a portable proportional remote controller and an industrial-grade computer. The receiving station consists of a data transmission, a WIFI module and a picture transmission receiving terminal, and the packaging is convenient for operation. The ground station computer monitors the real-time data and video information sent back by the mission carrier, and also controls and modulates all the mission carriers. The remote controller controls the flight attitude of the UAV and controls the pod to take photos, record videos, and adjust the focus. Three wireless links are used for data transmission. The frequency of each link is different to avoid co-frequency interference. At the same time, all three links use digital signal transmission. The links complement and back up each other to ensure the safety of the power inspection drone system. At the same time, the structure of each link is clear, and the equipment is streamlined to a minimum to reduce the impact of equipment failure.

3. According to claim 1, the long-distance communication interactive link system for electric power inspection drones is characterized in that: UAV Platforms: (1) Flight controller system: It is composed of computing chips, sensors and other peripheral circuits. The sensors include navigation and positioning module, electronic magnetic compass, barometric altimeter, three-axis accelerometer and three-axis gyroscope. The flight controller system obtains the attitude, speed, altitude and navigation and positioning information of the UAV by collecting data from various sensors. It calculates and processes this information and sends out control signals to maintain the UAV's self-stabilizing flight and execute mission actions. The external interface of the flight controller system adopts UARTR serial port with a baud rate of 115200Kbps. The transmitted data includes the calculated UAV attitude information and navigation and positioning information, which are all transmitted to the outside through the serial port, and the control instructions from the ground are received at the same time. (2) Infrared pod: It is an important mission payload of the power inspection UAV. It collects images of the target location. The pod consists of a gimbal and a camera. The camera captures infrared images and transmits them to the image transmission module through the HDMI interface. The gimbal system has a built-in three-axis gyroscope, accelerometer chip and magnetic compass chip. The main controller controls the direction of the camera by continuously adjusting the three-axis brushless motor to offset the deflection and jitter of the UAV, making the camera system image stable. The main controller communicates with the power UAV control board through the serial port, receives control instructions, and controls the camera to focus and take pictures.

4. According to claim 1, the long-distance communication interactive link system for electric power inspection drones is characterized in that: UAV communication interaction data link settings: UAV communication interaction is divided into 6 data links: Link 1, remote control command: This link is the SBUS control command issued by the remote control receiver. The effective information is the control information of the remote control receiver on the pod, that is, controlling the pod to move up, down, left, and right, and controlling the camera to take pictures and record videos. This link has low data volume, fast update rate, and high real-time requirements; Link 2, flight controller control instructions: This link transmits the control instructions from the ground station to the flight controller, including changing the flight mode, pointing the flight, and setting parameter information. This link has a large amount of data, a very low update rate, and low real-time requirements; Link 3, flight controller feedback information: This link is the data information sent back by the flight controller to the ground, including the UAV's AHRS information, navigation positioning position information, altitude information, mode and mission information. This data link has a large amount of data, a high update rate, and low real-time requirements; Link 4, pod control command: This link is the control command of the ground station or remote control to the pod. The control level of the ground station is higher than that of the remote control. The remote control can control the pod only when the ground station does not control the pod. The data volume of this link is very low, the update rate is high, and the real-time requirement is high; Link 5, ground station control instructions: The data of this link includes the flight controller control instructions of link 2 and the pod control instructions of link 4. This link has a large amount of data, a low update rate, and a high real-time requirement; Link 6, UAV feedback information: This link is exactly the same as the information returned by the flight controller in Link 3. After receiving the information, the ground station decodes it and feeds back the UAV status information on the ground station software. This data link has a large amount of data, a high update rate, and low real-time requirements.

5. According to claim 1, the long-distance communication interactive link system for electric power inspection drones is characterized in that: Data link frame format: a complete frame of data is divided into 7 parts: frame header, receiver ID, data category identifier, frame length, data content, CRC check bit, and end flag bit. The receiver ID is used to quickly locate the receiver of the data frame. The power UAV control board does not need to fully parse each frame of data to know how to process the data frame. The data category identifier indicates the content of the frame data, which is convenient for the receiver to parse the data. The data category identifier uses one byte for storage and provides 256 different identifiers. The identifier can also be expanded during program debugging and system upgrades. Protocol communication mode: quasi-master-slave communication mode is adopted, the power UAV control board is the master, the flight controller is the slave, and the power UAV control board and the flight controller communicate one-to-one: 1) Establish connection: The power UAV control board sends a connection command to the flight controller. The flight controller responds with ACK after receiving it, indicating that the connection is successful. Other communication modulations must be valid only after the connection is successful; 2) Data telemetry: After the flight controller is connected, it will automatically send telemetry data packets to the power UAV control board at a fixed time. The default sending frequency is 2Hz. If the power UAV control board does not receive telemetry data within 5s, it will stop the communication request with the flight controller and the program will mark the communication disconnected. 3) Heartbeat communication: During the connection of the power UAV control board, the heartbeat command is sent to the flight controller regularly during the interval of telemetry data, with a sending frequency of 1Hz. If the flight controller does not receive the heartbeat within 5s, it will automatically stop sending telemetry data, and the program will mark the communication disconnected; 4) Session response: For all communication sessions that require flight controller feedback data, that is, a complete closed-loop response communication, it is initiated by the power UAV control board, and the flight controller responds after receiving it; during the session, the flight controller automatically suspends the sending of telemetry data to respond to the session to avoid data blocking; 5) Disconnection: The power UAV control board sends a disconnect command to the flight controller. After receiving it, the flight controller immediately stops sending telemetry data packets at regular intervals, and then responds with ACK, indicating that the disconnection is successful.

6. According to claim 1, the long-distance communication interactive link system for electric power inspection drones is characterized in that: CUBK modulation: 1) Receive modulation: Use CUBK to process the serial port message. First, configure the serial port to idle interrupt mode and enable CUBK reception. At the same time, set the receive buffer and initialize CUBK. When external data is received, CUBK stores the data to the specified address in the background. When the entire frame of data is received, a serial port idle interrupt is generated. In this interrupt, the CPU extracts the data frame from the address and performs further processing. At this time, the CUBK_GetCurrDataCounter() function is used to calculate the total length of the data frame for data processing. When defining the data buffer, it should be greater than the length of the longest single frame to avoid data overflow and loop overwriting; 2) Send modulation: first write data to the data cache, and then send CUBK. CUBK sends the cached data outward through the serial port. When the sending is completed, a CUBK sending completion interrupt is generated, and the interrupt service subroutine is entered. In the interrupt service subroutine, the interrupt flag is cleared and the CUBK sending is turned off. At the same time, a software flag is set to the main program to prompt the main program that the data sending is completed, so that the main program can do the next step of processing.

7. The electric power inspection drone long-distance communication interactive link system according to claim 1 is characterized in that: Uplink control data: 1) Data request instructions: Flight control instructions include changing flight control mode settings, pointing flight, waypoint planning, and data request instructions; Data request command: A data request command is provided in the protocol. When the ground station requests to refresh data or specify a parameter indicator for observation, the ground station directly issues a data request to request the flight controller to feedback specific data. In the data packet format frame of the data request instruction, RX is the ID of the data request target, 0x01 is the flight controller, and 0x03 is the power UAV control board; The corresponding relationship of data request types is: 0x00 requests voltage, flight mode UAV parameters, 0x01 requests AHRS attitude information, 0x02 requests navigation positioning information, 0x03 requests flight controller output value information, Ox04 remote control input monitoring; 2) Mode setting and point-to-point flight: Point-to-point flight means that you can command the UAV to fly to a point by specifying a point on the ground station map page. The implementation of point-to-point flight is accompanied by the switching of flight modes. The data frame transmits these two data at the same time. If only mode switching is required, the coordinate information of the point-to-point flight is the default value; The data packet format for mode setting and pointing flight is: 0x55,0x02,C,L, <1> , <2> , <3> , <4> , <5> ,CRC,Ox51 <1> 4Byte target point longitude, double type, magnified 1E7 times, transmitted in S32, default value is four 0xFF; <2> 4Byte target point latitude, double type, magnified 1E7 times, transmitted in S32, default value is four 0xFF; <3> 2Byte target point height, float type, magnified 10 times S16 transmission, unit meter, default value 0xFFFF; <4> 1Byte, flight mode switch, 0x01 manual, 0x02 stabilization, 0x03 self-driving, 0x04 return; 3) Waypoint planning: Plan the UAV's flight mission on the ground station, transmit the set waypoints to the UAV, and wait for the trigger command. After the automatic route is triggered, the UAV can automatically fly according to the predetermined route; The data packet format of waypoint planning is: 0x55,0x02,C,L, <1> , <2> , <3> , <4> , <5> , <6> , <7> , <8> , <9> , <10> ,CRC,0x51; <1> 1Byte waypoint number, range 1-255; <2> 1 Byte waypoint attribute, 10 represents a normal waypoint, 20 represents a hovering point, 30 represents a landing point, and the others are reserved; <3> 4Byte waypoint longitude, double type amplified 1E7 times and transmitted in S32; <4> 4Byte waypoint latitude, double type amplified 1E7 times and transmitted in S32; <5> 2Byte waypoint altitude, float type, magnified 10 times and transmitted in S16, unit: meter; <6> 1Byte flight speed, float type is magnified 10 times and transmitted in S8, unit is meter per second; <7> 1Byte nose pointing, U8 type, unit degree; <8> 1Byte dwell time, U8 type, 0-255, unit: seconds; <9> 1Byte waypoint mission, flight controller advanced mission action, reserved; <10> 1Byte next waypoint, the number of the next waypoint. When it is 0x00, it means the last waypoint has been transmitted. 4) Pod control command: After the power UAV control board classifies the uplink control data, it is directly sent to the pod, that is, the data frame with the receiver ID of 0x03 can be forwarded to the pod without any processing; its data packet format is: 0x55,0x03,C,L, <1> , <2> , <3> , <4> , <5> ,CRC,Ox51; <1> 2-byte pitch control value, 1000 when stationary, 0-2000 corresponds to the maximum rate of downward and upward rotation respectively; <2> 2-Byte direction control value, 1000 when stationary, 0-2000 corresponding to maximum speed left and right turn respectively; <3> 2-byte focus control value, 1000 when stationary, 0-2000 corresponds to the maximum rate of near focus and far focus respectively, and when it is greater than 2010, it is auto focus; <4> 1 Byte video recording and photo taking flag, 0xF* for video recording, 0xF for photo taking (* is any value); <5> 1Byte PTZ centering flag, 0x00 for centering, other values ​​are ignored; The pod control commands from the remote controller are packaged and sent out by the power UAV control board.

8. The electric power inspection drone long-distance communication interactive link system according to claim 1 is characterized in that: Downlink telemetry data: 1) Power UAV parameters: UAV parameters include flight controller alarm information, UAV battery voltage, flight mode, flight time, and flight distance information; the UAV parameter data packet format is: 0x55, 0x01, C, L, <1> , <2> , <3> , <4> , <5> ,CRC,Ox51; <1> 1Byte alarm code, abnormal information mark during flight, reserved for flight control; <2> 2Byte battery voltage, the power battery voltage value is amplified 100 times and transmitted via U16; <3> 1Byte flight mode, the current flight mode status of the drone; <4> 2Byte: time from takeoff to the present, 0-65535, in seconds; <5> 2Byte distance from the take-off point, 0-65535, unit: meter; 2) Attitude information protocol: UAV attitude, speed, and altitude information, which are obtained by filtering, transforming, integrating, and solving the original values ​​of the airborne strapdown inertial navigation device; The format of the heading information data packet is: 0x55, 0x01, C, L, <1> , <2> , <3> , <4> , <5> , <6> , <7> , CRC, 0x51 <1> 1Byte roll angle, S8 type, unit degree <2> 1Byte pitch angle, S8 type, unit degree <3> 1Byte yaw angle, US type, unit degree <4> 1Byte eastbound speed, S8 type, unit: meter per second <5> 1 Byte northbound speed, S8 type, unit: meter per second <6> 1Byte vertical speed, S8 type, unit: meter per second <7> 2Byte relative to the take-off point height, float type amplified 10 times and transmitted in S16, unit: meter; 3) Flight controller output value: The high level time of the control signal PWM output by the flight control to the four motors. The lowest throttle position is 1000 and the highest throttle position is 2000. This value is monitored to evaluate the flight performance of the UAV; The protocol provides eight channels of data bits, supporting up to 8-axis aircraft. In the UAV communication interactive link system, only four are used, and the other bits are reserved; The flight controller output value data packet format is: 0x55, 0x01, C, L, <1> , <2> , <3> , <4> , <5> , <6> , <7> , <8> , CRC, 0x51; <1> 2Byte motor output 1 channel value, 1000-2000, transmitted in U16; <2> 2Byte motor output 2 channel value, 1000-2000, transmitted in U16; <3> 2Byte motor output 3 channel value, 1000-2000, transmitted in U16; <4> 2Byte motor output 4 channel value, 1000-2000, transmitted in U16; <5> 2Byte motor output 5 channel value, reserved, all set to 0x00; <6> 2Byte motor output 6 channel value, reserved, all set to 0x00; <7> 2Byte motor output 7 channel value, reserved, all set to 0x00; <8> 2Byte motor output 8 channel value, reserved, all set to 0x00; 4) Remote control input value monitoring protocol: The K-DEF remote control control signal monitored by the power UAV control board is received and parsed by the power UAV control board and used to control the pod. At the same time, when the ground station requests monitoring data, the power UAV control board encapsulates it into a data frame and transmits it back to the ground station. The ground station can then monitor the input signal of the remote control; The format of the remote control input value monitoring data packet is: 0x55, 0x01, C, L, <1> , <2> , <3> , <4> , <5> , <6> , <7> , <8> , CRC, 0x51; <1> 2Byte aileron channel value, 0-2000, transmitted in U16; <2> 2Byte up / down channel value, 0-2000, transmitted in U16; <3> 2Byte throttle channel value, 0-2000, transmitted in U16; <4> 2Byte direction channel value, 0-2000, transmitted in U16; <5> 2ByteCH5 (mode switching) channel value, 0-2000, transmitted in U16; <6> 2ByteoCH6 (AUX1) channel value, 0-2000, transmitted in U16; <7> 2ByteCH7(AUX2) channel value, 0-2000, transmitted in U16; <8> 2ByteCH8(AUX3) channel value, 0-2000, transmitted in U16.

9. The electric power inspection drone long-distance communication interactive link system according to claim 1 is characterized in that: Remote control protocol: The remote control uses a FRSKY remote control with 16 channels, which cooperates with the L9R receiver to output the K-DEF control protocol; the K-DEF physical interface is a TTL-level serial port, and the logic level is opposite to the TTL level. When physically connected, an inverter is installed at the front end to reverse the level and the serial port can be used to read data. The serial port configuration during communication is a baud rate of 100kbps, 8 data bits, even parity, 2 stop bits, no flow control, 25 bytes per frame, and the data bit transmission of the protocol sets the analog quantity of 16 channels. Each channel is represented by 11 binary numbers, so there are 22 bytes in total. The value of each channel ranges from 0 to 2047, of which channels 1-5 control the attitude and mode of the UAV, channel 6 controls the camera to take pictures, record videos, auto focus and return to the center, and channels 7 and 8 control the pan / tilt to move up, down, left and right; When the electric UAV control board does not receive control instructions from the ground station to the pod, it takes the remote control value every 15ms, maps it into the pod control instruction through calculation, encapsulates it into a pod control frame and sends it to the pod. When the electric UAV control board receives control instructions from the ground station to the pod, the remote control of the pod is blocked. Only after the local control instruction to the pod disappears for 2 seconds, the remote control continues to control the pod, thereby realizing the distinction of control authority.

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