CN110764538B - Three-axis stable platform and tracking method for UAV based on three-step adaptive algorithm - Google Patents

Abstract

The invention discloses a three-axis stable platform and a tracking method for an unmanned aerial vehicle based on a three-step self-adaptive algorithm. The platform includes photoelectric switch, three-axis stabilized gyro, sensor acquisition MCU, antenna control board MCU, feed source, beacon machine, slip ring, positioning system, motor driver and motor. The method is: the aerial platform sends the location information of the local end, and the ground system performs target acquisition; the photoelectric switch and the three-axis stabilized gyroscope transmit the information to the sensor acquisition MCU, and the sensor acquisition MCU performs data preprocessing, and sends the antenna status to the antenna control board MCU; Antenna control board MCU controls the motor driver through comprehensive calculation, so that the antenna always maintains the best communication posture. The invention adopts a three-step tracking algorithm in the tracking process, adopts a closed-loop PID feedback control mode to suppress carrier interference, and adopts a disturbance compensation method to suppress carrier disturbance, thereby solving the problem of platform overtop, and has high tracking accuracy, fast response speed and high stability.

Description

Three-axis stable platform and tracking method for UAV based on three-step adaptive algorithm

technical field

The invention belongs to the technical field of motor control, in particular to a three-axis stable platform and tracking method for an unmanned aerial vehicle based on a three-step self-adaptive algorithm.

Background technique

The stabilized platform is a device used to keep the stabilized object stable relative to a certain orientation. Its main feature is that the gyroscope is widely used as an angular motion sensitive element. The technical means used belong to the category of inertial technology research. Its unique function is to isolate Carrier disturbance, by measuring the change of platform attitude and position, accurately maintains the dynamic attitude reference of the carrier, and realizes automatic tracking of maneuvering targets through image detection equipment, so it has always been an enduring research topic in various countries. Stabilized platforms are widely used in industry. On aerial photographic observation equipment, stabilized platforms can accurately align photographic equipment with the target to obtain more accurate and clear images; The development of various industries such as cash transport vehicles, public security, fire protection, etc. requires a platform with stable tracking capabilities to isolate the impact of the movement of the carrier on the platform attitude, and to ensure the interception and identification of target signals under various weather conditions. and track. In addition, stable tracking platforms have been widely used in deep-sea operations such as airborne target indicators, space remote sensing detection, and submarine sonar detection.

American RaySat Antenna Systems (RAS for short) company is the world's more advanced manufacturer of antenna equipment for mobile communication systems. The main application in the United States is military communication. Now RaySat antenna equipment is in service in many parts of the world. The StealthRay series vehicle-mounted mobile communication platform equipment produced by it supports two-way communication. It can automatically track and maintain the pointing by automatically controlling the azimuth, pitch and polarization angle during the movement of the vehicle, and supports the two-way 2Mbps transmission rate of the vehicle at a speed of 350km per hour. . my country's scientific and technological institutes engaged in national important military and civilian large-scale electronic information systems, communications and electronic equipment. The research related product systems include portable antennas, vehicle-mounted antennas and ship-mounted antennas. The vehicle-mounted antenna system uses gyro stabilization, inertial navigation tracking and Controlled electronic beam scanning and tracking technology keeps the antenna always aligned with the satellite with high precision to ensure smooth communication, while phase-controlled electronic beam scanning and tracking can correct the inertial navigation data in real time, overcoming the inherent defect of inertial navigation data drifting with time, without timing Parking corrects the inertial navigation data, realizing stable tracking during long-term travel. For example, the SATPRO brand vehicle and ship-borne stability tracking equipment independently developed by DBS Measurement and Control Technology Co., Ltd. in Xi'an have been widely praised in civilian and military fields. In recent years, with the increasing demand for satellite communications in the international aviation field, DBS Measurement and Control has gradually entered the international market with SATPRO airborne antenna equipment by virtue of its advanced technology, strong R&D strength and accurate judgment on the market. Under the supervision of the Security Bureau, various related experiments have been successfully completed. SATPRO antenna equipment incorporates a number of industry-leading technologies such as GNSS/INS fusion attitude measurement system, cone scanning peak tracking, carrier attitude calculation, compensation algorithm and phased array communication, etc. Under the circumstances, the antenna can still be guaranteed to be stable to the star.

In terms of the stable tracking platform of the vehicle-mounted UAV, a platform with a two-axis structure is mainly used for tracking. When the tracking target is over the top, due to the limitation of the two-axis structure of the tracking platform, there will inevitably be tracking blind spots, which will affect the continuous and accurate tracking of the platform. And relatively speaking, the platform used for UAV tracking has low precision and cannot meet the requirements of high-precision tracking. In addition, the structure of the existing stabilizing platform is relatively wide, which is not suitable for small car bodies.

Contents of the invention

The purpose of the present invention is to provide a three-axis stable platform for unmanned aerial vehicles based on a three-step adaptive algorithm, which can solve the problem of over-the-top of the platform, and has high tracking accuracy, fast response speed and high stability.

The technical solution to realize the object of the present invention is: a kind of unmanned aerial vehicle three-axis stable platform based on three-step adaptive algorithm, including photoelectric switch, three-axis gyroscope, sensor acquisition MCU, antenna control board MCU, feed source, beacon machine , slip rings, positioning systems, motor drives and motors;

The photoelectric switch includes an azimuth photoelectric switch, a roll photoelectric switch and a pitch photoelectric switch, which are used to transmit the position information of the azimuth, roll and pitch to the sensor acquisition MCU through the GPIO port;

The three-axis gyroscope is used to transmit speed information and acceleration information to the sensor acquisition MCU;

The sensor collects the MCU, which is used to send a message to the antenna control board MCU through the serial port;

The feed source is the primary radiator of the high-gain antenna, which is used to converge the electric wave to itself to receive the maximum signal, and then transmit the signal to the slip ring;

The beacon machine is used to send the geographic location of the air platform to the antenna control board MCU;

The slip ring is used to receive the output signal of the feed source and the positioning system, and transmit the signal to the antenna control board MCU;

The positioning system, that is, the inertial navigation system, is used to provide the latitude and longitude information and altitude of the target, which will be transmitted to the slip ring;

The MCU of the antenna control board performs comprehensive calculation on the received signal, controls the motor driver, and thereby controls the motor to adjust the communication attitude of the mobile communication antenna;

The motor driver includes an azimuth motor driver, an azimuth motor driver and a pitch motor driver, which are used to drive the motor to run at a corresponding speed;

The motors, including azimuth motors, azimuth motors and pitch motors, are used to adjust the angle of the antenna so that the communication antenna in motion maintains an optimal communication posture.

As a specific example, the sensor acquisition MCU adopts STM32F103VET6, the antenna control board MCU adopts STM32F427VET6, the motor adopts AC servo motor, the photoelectric switch adopts KJT-ST676, and the three-axis gyroscope adopts ADIS16475-2 type MEMS gyroscope.

As a specific example, the MCU of the antenna control board sends the debugging information to the PC through USART1, and displays it on the PC, and outputs the debugging information of the antenna to check the results of the calculation and control, and assist the debugging of the antenna;

The MCU of the antenna control board is connected to the beacon machine through USART2 to obtain the geographical location information of the target;

The MCU of the antenna control board receives the inertial navigation system information in the positioning system through USART3, and adjusts the antenna alignment direction according to the inertial navigation information;

The MCU of the antenna control board receives the sensor to collect the information of the MCU through the USART4, and further adjusts the antenna alignment angle by processing the gyroscope information;

The MCU of the antenna control board sends speed commands to the azimuth motor driver through UART1, and controls the azimuth motor to run at the corresponding speed;

The MCU of the antenna control board sends speed commands to the roll motor driver through UART2, and controls the roll motor to run at the corresponding speed;

The MCU of the antenna control board sends speed commands to the pitch motor driver through UART3, and controls the pitch motor to run at the corresponding speed;

The MCU of the antenna control board is connected to the servo control equipment through the network port, and receives equipment-related information queries and antenna motion control commands;

The MCU of the antenna control board generates a PWM signal through the channel 2 of the timer 4 to control the STEP signal of the azimuth motor to control the rotation of the azimuth motor; the MCU of the antenna control board generates a PWM signal through the channel 2 of the timer 5, It is used to control the STEP signal of the roll motor to control the rotation of the roll motor; the MCU of the antenna control board generates a PWM signal through channel 1 of timer 8 to control the STEP signal of the pitch motor to control the rotation of the pitch motor .

A tracking method for a three-axis stabilized platform of an unmanned aerial vehicle based on a three-step adaptive algorithm, comprising the following steps:

Step 1. The aerial platform sends the local geographic location information through the beacon channel, and the ground system completes target acquisition and tracking according to the geographic location information provided by the beacon channel;

Step 2, the photoelectric switch transmits the azimuth, roll and pitch information to the sensor acquisition MCU through the GPIO port, and the three-axis gyroscope transmits the speed information and acceleration information to the sensor acquisition MCU;

Step 3, the sensor acquisition MCU reads the speed information and acceleration information in the three-axis gyroscope through the SPI interface, performs data preprocessing, and sends a message of the antenna status to the antenna control board MCU through the serial port;

Step 4: After comprehensive calculation, the MCU of the antenna control board controls the motor driver and adjusts the communication posture of the mobile communication antenna.

As a specific example, the aerial platform described in step 1 sends the local geographic location information through the beacon channel, and the ground system completes target acquisition and tracking according to the geographic location information provided by the beacon channel, as follows:

Step 1.1, using ground equipment to send beacon inquiry signals in TDMA mode in the target acquisition stage, that is, each user station sends beacon inquiry signals at different time periods based on Beidou timing;

Step 1.2, the air platform sends a beacon response signal after receiving the ground equipment inquiry signal, and remains silent at other times;

Step 1.3, the ground equipment performs target acquisition and network access operations, stops sending beacon inquiry signals, and completes geographic location information update by the business channel.

As a specific example, the ground equipment described in step 1.3 performs target acquisition and network entry operations, as follows:

Step 1.3.1: Align the target position through coarse alignment. When the target is within 3Km, the antenna pitch motor scans at a speed of 0.533°/S; Scan at a speed of /S; when the antenna is outside the range of 15Km, the antenna pitch motor scans at a speed of 0.133°/S; the azimuth motor always scans at a speed of 60°/S, and the total capture time of the system is 43.5 seconds;

In step 1.3.2, the target is further aligned through fine alignment, and the fine alignment adopts a conical scanning algorithm to capture the target.

As a specific example, the MCU of the antenna control board described in step 4 controls the motor driver and adjusts the communication attitude of the mobile communication antenna after comprehensive calculation, including using a three-step tracking algorithm to control the motors on the α, β, and γ axes to track the target , the α, β, and γ axes correspond to the azimuth axis, pitch axis, and roll axis respectively. The steps are as follows:

Step 4.1, when the target is in the ascending stage and the elevation angle is less than 75 degrees, keep the γ axis still, and track the target by rotating the α and β axes;

Step 4.2, when the target is at an elevation angle greater than 75 degrees, keep the α-axis still, and track the target by rotating the β-axis and the γ-axis;

Step 4.3, when the target is in the descending stage and when the elevation angle is less than 75 degrees, the γ-axis does not move, and the target is tracked by rotating the α and β-axis.

As a specific example, the MCU of the antenna control board described in step 4 controls the motor driver and adjusts the communication posture of the mobile communication antenna after comprehensive calculation, including using a closed-loop PID feedback control method to suppress carrier interference. The steps are as follows:

具体的系数由实际中通过调节得到；由电流传感器构成电流环反馈回路，采用一个电流反馈系数β₁和一个滤波器

构成电流环反馈回路；中环速度环和外环稳定环均采用PID控制算法；其中K₁是电流调节器的增益系数、T₁是电流调节器的时间常数、s表示复数、T_A是滤波器的时间常数。The innermost loop of the closed-loop PID feedback control mode is the current loop, and the transfer function model of the current regulator is

The specific coefficient is obtained through adjustment in practice; the current loop feedback loop is formed by the current sensor, and a current feedback coefficient β ₁ and a filter are used

Constitute the current loop feedback loop; the speed loop of the middle loop and the stability loop of the outer loop both adopt the PID control algorithm; where K ₁ is the gain coefficient of the current regulator, T ₁ is the time constant of the current regulator, s represents a complex number, and T _A is a filter time constant.

Compared with the prior art, the present invention has significant advantages in that: (1) it adopts three axes of pitch, roll and azimuth to track the target, and the tracking target is faster and more stable; (2) it adopts a three-axis structure and adopts three-step switching The tracking algorithm solves the over-the-top problem of target tracking; (3) the use of stm32 series makes the tracking system have the characteristics of fast processing speed and strong anti-interference ability; (4) the chip used is small in size and the overall control board is small, which is convenient Analog and practical.

Description of drawings

Fig. 1 is the structural block diagram of the unmanned aerial vehicle three-axis stabilization platform based on the three-step adaptive algorithm of the present invention.

Fig. 2 is a structural block diagram of the MCU of the antenna control board in the present invention.

Fig. 3 is a structural block diagram of the sensor acquisition MCU in the present invention.

Fig. 4 is a schematic flow chart of a cone scanning algorithm in a specific embodiment of the present invention.

Fig. 5 is a coordinate diagram of a three-axis system in a specific embodiment of the present invention.

Fig. 6 is a coordinate diagram of a space Cartesian coordinate system established in a specific embodiment of the present invention.

Fig. 7 is a schematic flowchart of a closed-loop PID feedback control method in a specific embodiment of the present invention.

Fig. 8 is a schematic flowchart of a disturbance compensation control system in a specific embodiment of the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

In conjunction with Fig. 1, the present invention is based on a three-step self-adaptive algorithm for a UAV three-axis stabilization platform, including a photoelectric switch 1, a three-axis gyroscope 2, a sensor acquisition MCU 3, an antenna control board MCU 4, a feed source 5, and a beacon machine 6, slip ring 7, positioning system 8, motor driver 9 and motor 10;

The photoelectric switch 1 includes an azimuth photoelectric switch, a roll photoelectric switch and a pitch photoelectric switch, which are used to transmit the position information of the azimuth, roll and pitch to the sensor acquisition MCU3 through the GPIO port;

The three-axis gyroscope 2 is used to transmit speed information and acceleration information to the sensor acquisition MCU3;

The sensor collects MCU3, which is used to send a message to the antenna control board MCU4 through the serial port;

The feed 5 is the primary radiator of the high-gain antenna, which is used to converge the electric wave to itself so as to receive the maximum signal, and then transmit the signal to the slip ring 7;

The beacon machine 6 is used to send the geographical position of the aerial platform to the antenna control board MCU4;

The slip ring 7 is used to receive the output signal of the feed source 5 and the positioning system 8, and transmit the signal to the antenna control board MCU4;

The positioning system 8, that is, the inertial navigation system, is used to provide the longitude and latitude information and the altitude of the target, which will be transmitted to the slip ring 7;

The antenna control board MCU4 comprehensively calculates the received signal, controls the motor driver 9, and thereby controls the motor 10 to adjust the communication attitude of the antenna in motion;

The motor driver 9 includes an azimuth motor driver, an azimuth motor driver and a pitch motor driver, which are used to drive the motor 10 to run at a corresponding speed;

The motor 10 includes an azimuth motor, an azimuth motor and a pitch motor, and is used to adjust the angle of the antenna so that the communication antenna in motion maintains an optimal communication posture.

The sensor acquisition MCU 3 reads information such as speed and acceleration in the three-axis gyroscope through the SPI interface, and performs data preprocessing; the photoelectric switch 1 transmits the orientation, roll and pitch information to the sensor acquisition MCU 3 through the GPIO port, The sensor acquisition MCU 3 sends a message of the antenna status to the antenna control board MCU 4 through the serial port according to the feedback information from the IMU and the photoelectric switch 1. The antenna control board MCU 4 perceives the motion state of the antenna in motion through the sensor acquisition board MCU 3, and according to the information of the IMU, inertial navigation, beacon machine 6, and photoelectric switch 1, the processor controls the motor driver 9 through comprehensive calculation, so that The mobile communication antenna always maintains the best communication posture to ensure the stability of the communication process, and communicates control and status information with the indoor unit through the network port.

In conjunction with Fig. 2, the photoelectric switch 1 of the present invention transmits the orientation, roll and pitch information to the sensor acquisition MCU 3 through the GPIO port, and the three-axis gyroscope 2 transmits the speed and acceleration information to the sensor acquisition MCU 3, and the sensor acquisition MCU 3 uses STM32F103VET6 . STM32F103VET6 built-in FLASH space 512K, CPU built-in 20K SRAM, the highest frequency of CPU is 72MHz, 3 general-purpose timers, 1 advanced timer, 2 SPI interfaces, 3 usart interfaces; the three-axis gyro 2 uses ADIS16475 of AD Company -2 type MEMS gyroscope, ADIS16475-2 is an IMU, including gyroscope and accelerometer, in addition to providing gyroscope information, it can also calculate pitch and roll attitude information through a certain algorithm.

In conjunction with Fig. 3, the sensor acquisition board MCU 3 of the present invention reads the speed and acceleration information in the three-axis gyroscope 2 through the SPI interface, performs data preprocessing, and then sends a message to the antenna control board MCU 4 by the antenna state through the serial port, and the antenna control The version MCU 4 controls the motor driver 9 through comprehensive calculation, so that the mobile communication antenna always maintains the best communication posture and ensures the stability of the communication process. The sensor acquisition MCU3 adopts STM32F103VET6, the antenna control board MCU4 adopts STM32F427VET6, the motor 10 adopts an AC servo motor, the photoelectric switch 1 adopts KJT-ST676, and the three-axis gyroscope 2 adopts ADIS16475-2 type MEMS gyroscope.

Further, the antenna control board MCU 4 sends the debugging information to the PC end through the USART1, and displays it on the PC side, and outputs the debugging information of the antenna to check the results of calculation and control, and assist the debugging of the antenna; the antenna control board MCU 4 Connect with the beacon machine 6 through USART2 to obtain target-related information; the antenna control board MCU4 receives the inertial navigation system information in the positioning system through USART3, and adjusts the antenna alignment direction according to the inertial navigation information; the antenna control board MCU 4 passes through USART4 , the receiving sensor collects the information of MCU 3, and further adjusts the antenna alignment angle by processing the gyroscope information; the antenna control board MCU 4 sends speed instructions to the azimuth motor driver through UART1, and controls the azimuth motor to run at the corresponding speed; the antenna The control board MCU 4 sends speed commands to the roll motor driver through UART2, and controls the roll motor to run at the corresponding speed; the antenna control board MCU 4 sends speed commands to the pitch motor driver through UART3, and controls the pitch motor to run at the corresponding speed ;Antenna control board MCU 4 is connected to the servo control device through the network port, accepts device-related information query and antenna motion control commands, and receives feedback result information; Antenna control board MCU 4 generates a PWM signal through channel 2 of timer 4 , used to control the STEP signal of the azimuth motor to control the rotation of the azimuth motor; the antenna control board MCU 4 generates a PWM signal through the channel 2 of the timer 5 to control the STEP signal of the roll motor to control the roll motor The rotation of the antenna control board MCU 4 through the channel 1 of the timer 8 generates a PWM signal to control the STEP signal of the pitch motor to control the rotation of the pitch motor.

A tracking method for a three-axis stabilized platform of an unmanned aerial vehicle based on a three-step adaptive algorithm, comprising the following steps:

Step 1. The aerial platform sends the local geographic location information through the beacon channel, and the ground system completes target acquisition and tracking according to the geographic location information provided by the beacon channel;

Step 2, the photoelectric switch 1 transmits the azimuth, roll and pitch information to the sensor acquisition MCU3 through the GPIO port, and the three-axis gyroscope 2 transmits the speed information and acceleration information to the sensor acquisition MCU3;

Step 3, the sensor acquisition MCU3 reads the speed information and acceleration information in the three-axis gyroscope 2 through the SPI interface, performs data preprocessing, and sends a message to the antenna control board MCU4 through the serial port of the antenna state;

Step 4: After comprehensive calculation, the antenna control board MCU4 controls the motor driver 9 to adjust the communication posture of the mobile communication antenna to ensure the stability of the communication process.

Further, the aerial platform described in step 1 sends the local geographic location information through the beacon channel, and the ground system completes target acquisition and tracking according to the geographic location information provided by the beacon channel, as follows:

Step 1.1, using ground equipment to send beacon inquiry signals in TDMA mode in the target acquisition stage, that is, each user station sends beacon inquiry signals at different time periods based on Beidou timing;

Step 1.2, the air platform sends a beacon response signal after receiving the ground equipment inquiry signal, and remains silent at other times;

Step 1.3, the ground equipment performs target acquisition and network access operations, stops sending beacon inquiry signals, and completes geographic location information update by the business channel.

Further, the ground equipment described in step 1.3 performs target acquisition and network access operations, as follows:

Step 1.3.1, roughly align the target position through coarse alignment. When the target is within 3Km, the antenna pitch motor scans at a speed of 0.533°/S; Scan at a speed of /S; when the antenna is outside the range of 15Km, the antenna pitch motor scans at a speed of 0.133°/S; the azimuth motor always scans at a speed of 60°/S, and the total capture time of the system is 43.5 seconds;

In step 1.3.2, the target is more accurately aligned through fine alignment. The fine alignment uses a conical scanning algorithm to capture the target with high precision, as shown in Figure 4.

Further, the antenna control board MCU4 described in step 4 controls the motor driver 9 through comprehensive calculation, and adjusts the communication attitude of the antenna in motion, including using a three-step tracking algorithm to control the motors on the α, β, and γ axes to track the target, α The , β, and γ axes correspond to the azimuth, pitch, and roll axes respectively. The steps are as follows:

Step 4.1, when the target is in the ascending stage and the elevation angle is less than 75 degrees, keep the γ axis still, and track the target by rotating the α and β axes;

Step 4.2, when the target is at an elevation angle greater than 75 degrees, keep the α-axis still, and track the target by rotating the β-axis and the γ-axis;

Step 4.3, when the target is in the descending stage and when the elevation angle is less than 75 degrees, the γ-axis does not move, and the target is tracked by rotating the α and β-axis.

The theoretical analysis of the three-step tracking algorithm to solve the problem of the target over the top is as follows:

The three-axis system is shown in Figure 5, including three parts of azimuth, pitch and roll, which correspond to the three rotation axes of α-axis, β-axis and γ-axis respectively. The intersection point O of the three rotation axes is fixed, and the direction OS points to is the observation direction. The system takes O as the coordinate origin, the due east direction as the positive direction of the x-axis, the due north direction as the positive direction of the y-axis, and the direction of the zenith as the positive direction of the z-axis. A spatial Cartesian coordinate system is established as shown in Figure 6. When (α, β, γ) = (0, 0, 0), it is stipulated that the α-axis coincides with the z-axis, the β-axis coincides with the x-axis, and the γ-axis coincides with the y-axis. At this time, the observation direction OS points to Zenith 3 The positive direction of shaft rotation is shown in Figure 6.

The rotation angles of the three axes are α, β and γ respectively, and the value ranges are as follows:

0≤α<360°, -90°≤β≤90°, -90°≤γ≤90°

Set the rotation matrices of the α-axis, β-axis and γ-axis as:

Set the distance between the space target S and the coordinate origin O to be the unit length, the coordinates of S in the coordinate system are (x, y, z), and the three-axis platform is rotated (α, β, γ) so that the observation direction is aligned with the target S, then (x, y, z) and (α, β, γ) are related as follows:

The three-step tracking algorithm refers to that when the tracking target is in the rising stage and when the pitch angle is less than 75 degrees, keep the α axis still and track the target by rotating the β axis and the γ axis. Since the α axis remains stationary, let α = 0, from the above formula:

After derivation, we can get:

Finally available:

和

都不是无穷大，且其值随着γ值的减小而减小；当目标过顶时,

和

随着俯仰角的减小而减小,因此三轴系统可以采用三步跟踪算法来解决过顶问题。When γ≠0, that is, when the target is above the water level,

and

are not infinite, and their value decreases with the decrease of γ value; when the target is over the top,

and

As the pitch angle decreases, it decreases, so the three-axis system can use a three-step tracking algorithm to solve the overhead problem.

Further, the antenna control board MCU4 described in step 4 controls the motor driver 9 and adjusts the communication posture of the mobile communication antenna after comprehensive calculation, including adopting a closed-loop PID feedback control method to suppress carrier interference. Referring to FIG. 7, the steps are as follows:

具体的系数由实际中通过调节得到；由电流传感器构成电流环反馈回路，采用一个电流反馈系数β₁和一个滤波器

构成电流环反馈回路；中环速度环和外环稳定环均采用PID控制算法；其中K₁是电流调节器的增益系数、T₁是电流调节器的时间常数、s表示复数、T_A是滤波器的时间常数。The innermost loop of the closed-loop PID feedback control mode is the current loop, and the transfer function model of the current regulator is

The specific coefficient is obtained through adjustment in practice; the current loop feedback loop is formed by the current sensor, and a current feedback coefficient β ₁ and a filter are used

Constitute the current loop feedback loop; the speed loop of the middle loop and the stability loop of the outer loop both adopt the PID control algorithm; where K ₁ is the gain coefficient of the current regulator, T ₁ is the time constant of the current regulator, s represents a complex number, and T _A is a filter time constant.

Further, the system adopts the disturbance compensation method to suppress the carrier disturbance, combined with Figure 8, the details are as follows:

Firstly, the angular velocity in the azimuth direction of the platform is detected, and then the platform is controlled to rotate in the opposite direction at the same speed, so as to reduce the influence of disturbance on the system.

The present invention uses three axes of pitch, roll and azimuth to track the target, and the tracking target is faster and more stable; it adopts a three-axis structure, and adopts a three-step switching tracking algorithm, which solves the problem of over-the-top tracking of the target; adopts the stm32 series, making the tracking The system has the characteristics of fast processing speed and strong anti-interference ability; the chip used is small in size and the overall control board is small, which is convenient for simulation and practicality.

Claims (7)

1. a kind of unmanned aerial vehicle three-axis stable platform based on three-step self-adaptive algorithm, it is characterized in that, comprise photoelectric switch (1), three-axis gyroscope (2), sensor gathers MCU (3), antenna control board MCU (4 ), feed source (5), beacon machine (6), slip ring (7), positioning system (8), motor driver (9) and motor (10); The photoelectric switch (1) includes an azimuth photoelectric switch, a roll photoelectric switch and a pitch photoelectric switch, which are used to transmit the position information of the azimuth, roll and pitch to the sensor acquisition MCU (3) through the GPIO port; The three-axis gyroscope (2) is used to transmit speed information and acceleration information to the sensor acquisition MCU (3); The sensor collects the MCU (3), which is used to send a message to the antenna control board MCU (4) through the serial port; The feed source (5) is the primary radiator of the high-gain antenna, which is used to converge the electric wave to itself so as to receive the maximum signal, and then transmit the signal to the slip ring (7); The beacon machine (6) is used to send the geographic position of the aerial platform to the antenna control board MCU (4); The slip ring (7) is used to receive the output signal of the feed source (5) and the positioning system (8), and transmit the signal to the antenna control board MCU (4); The positioning system (8), i.e. the inertial navigation system, is used to provide the latitude and longitude information and altitude of the target, which will be transmitted to the slip ring (7); The antenna control board MCU (4) comprehensively calculates the received signal, controls the motor driver (9), thereby controls the motor (10) to adjust the communication attitude of the mobile communication antenna, as follows: The innermost loop of the closed-loop PID feedback control mode is the current loop, and the transfer function model of the current regulator is

The specific coefficient is obtained through adjustment in practice; the current loop feedback loop is formed by the current sensor, and a current feedback coefficient β ₁ and a filter are used

Constitute the current loop feedback loop; the speed loop of the middle loop and the stability loop of the outer loop both adopt the PID control algorithm; where K ₁ is the gain coefficient of the current regulator, T ₁ is the time constant of the current regulator, s represents a complex number, and T _A is a filter the time constant of The motor driver (9) includes an azimuth motor driver, an azimuth motor driver and a pitch motor driver, for driving the motor (10) to run at a corresponding speed; The motor (10), including an azimuth motor, an azimuth motor and a pitch motor, is used to adjust the angle of the antenna so that the communication antenna in motion maintains an optimal communication posture. 2. the unmanned aerial vehicle three-axis stable platform based on three-step adaptive algorithm according to claim 1, is characterized in that, described sensor gathers MCU (3) and adopts STM32F103VET6, and described antenna control panel MCU (4) adopts STM32F427VET6 , the motor (10) is an AC servo motor, the photoelectric switch (1) is KJT-ST676, and the three-axis gyroscope (2) is an ADIS16475-2 MEMS gyroscope. 3. the unmanned aerial vehicle three-axis stable platform based on three-step adaptive algorithm according to claim 1, is characterized in that, described antenna control panel MCU (4) sends debugging information to PC end by USART1, and in PC Terminal display, output the debugging information of the antenna, to view the results of operation and control, and assist in the debugging of the antenna; Antenna control board MCU (4) is connected with beacon machine (6) through USART2, obtains the geographical position information of target; The antenna control board MCU (4) receives the inertial navigation system information in the positioning system through USART3, and adjusts the antenna alignment direction according to the inertial navigation information; The antenna control board MCU (4) receives the sensor to collect the information of the MCU (3) through the USART4, and further adjusts the antenna alignment angle by processing the gyroscope information therein; The antenna control board MCU (4) sends speed commands to the azimuth motor driver through UART1, and controls the azimuth motor to run at the corresponding speed; The antenna control board MCU (4) sends speed commands to the roll motor driver through UART2, and controls the roll motor to run at the corresponding speed; The antenna control board MCU (4) sends speed commands to the pitch motor driver through UART3, and controls the pitch motor to run at the corresponding speed; The antenna control board MCU (4) is connected to the servo control equipment through the network port, and receives equipment-related information inquiries and antenna motion control commands; The antenna control board MCU (4) generates a PWM signal through the channel of the first timer to control the STEP signal of the azimuth motor to control the rotation of the azimuth motor; the antenna control board MCU (4) passes through the channel of the second timer , to generate a PWM signal to control the STEP signal of the roll motor to control the rotation of the roll motor; the antenna control board MCU (4) generates a PWM signal to control the pitch motor through the channel of the third timer STEP signal to control the rotation of the pitch motor. 4. A tracking method based on the three-step adaptive algorithm of the unmanned aerial vehicle three-axis stable platform, is characterized in that, comprises the following steps: Step 1. The aerial platform sends the local geographic location information through the beacon channel, and the ground system completes target acquisition and tracking according to the geographic location information provided by the beacon channel; Step 2, the photoelectric switch (1) transmits the azimuth, roll and pitch information to the sensor acquisition MCU (3) through the GPIO port, and the three-axis gyroscope (2) transmits the speed information and acceleration information to the sensor acquisition MCU (3); Step 3, the sensor acquisition MCU (3) reads the speed information and acceleration information in the three-axis gyroscope (2) through the SPI interface, performs data preprocessing, and sends a message to the antenna control board MCU (4) through the serial port of the antenna state; Step 4: After comprehensive calculation, the antenna control board MCU (4) controls the motor driver (9) to adjust the communication attitude of the mobile communication antenna. The steps are as follows: The innermost loop of the closed-loop PID feedback control mode is the current loop, and the transfer function model of the current regulator is

The specific coefficient is obtained through adjustment in practice; the current loop feedback loop is formed by the current sensor, and a current feedback coefficient β ₁ and a filter are used

Constitute the current loop feedback loop; the speed loop of the middle loop and the stability loop of the outer loop both adopt the PID control algorithm; where K ₁ is the gain coefficient of the current regulator, T ₁ is the time constant of the current regulator, s represents a complex number, and T _A is a filter time constant. 5. the tracking method of the unmanned aerial vehicle three-axis stable platform based on three-step self-adaptive algorithm according to claim 4, it is characterized in that, the air platform described in step 1 sends this end geographical position information by beacon channel, ground The system completes target acquisition and tracking based on the geographic location information provided by the beacon channel, as follows: Step 1.1, using ground equipment to send beacon inquiry signals in TDMA mode in the target acquisition stage, that is, each user station sends beacon inquiry signals at different time periods based on Beidou timing; Step 1.2, the air platform sends a beacon response signal after receiving the ground equipment inquiry signal, and remains silent at other times; Step 1.3, the ground equipment performs target acquisition and network access operations, stops sending beacon inquiry signals, and completes geographic location information update by the business channel. 6. the tracking method of the unmanned aerial vehicle three-axis stable platform based on three-step adaptive algorithm according to claim 5, is characterized in that, the ground equipment described in step 1.3 carries out target capture and network access operation, specifically as follows: Step 1.3.1: Align the target position through coarse alignment. When the target is within 3Km, the antenna pitch motor scans at a speed of 0.533°/S; Scan at a speed of /S; when the antenna is outside the range of 15Km, the antenna pitch motor scans at a speed of 0.133°/S; the azimuth motor always scans at a speed of 60°/S, and the total capture time of the system is 43.5 seconds; In step 1.3.2, the target is further aligned through fine alignment, and the fine alignment adopts a conical scanning algorithm to capture the target. 7. the tracking method of the unmanned aerial vehicle three-axis stable platform based on three-step adaptive algorithm according to claim 6, it is characterized in that, the antenna control board MCU (4) described in step 4 is through comprehensive calculation, controls motor driver (9), adjust the communication attitude of the mobile communication antenna, including using a three-step tracking algorithm to control the motors on the α, β, and γ axes to track the target. The α, β, and γ axes correspond to the azimuth axis, pitch axis, and roll axis respectively. Proceed as follows: Step 4.1, when the target is in the ascending stage and the elevation angle is less than 75 degrees, keep the γ axis still, and track the target by rotating the α and β axes; Step 4.2, when the target is at an elevation angle greater than 75 degrees, keep the α-axis still, and track the target by rotating the β-axis and the γ-axis; Step 4.3, when the target is in the descending stage and when the elevation angle is less than 75 degrees, the γ-axis does not move, and the target is tracked by rotating the α and β-axis.

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