阅读说明：本技术 一种基于机载Ka波段的卫星视频传输系统 (Satellite video transmission system based on airborne Ka wave band ) 是由 邢向荣 王力强 于 2019-11-13 设计创作，主要内容包括：本发明提供了一种基于机载Ka波段的卫星视频传输系统,包括：伺服控制子系统,其包括开环稳定模块、闭环跟踪模块和传感器融合模块,其中：开环稳定模块包括单惯性测量单元,单惯性测量单元用于测量载体的线加速度和角速率,开环稳定模块根据载体线加速度和角速率信息对天线进行控制；闭环跟踪模块对天线的指向进行校正,以保持天线准确地指向卫星；传感器融合模块对若干个传感器采集的数据进行融合,以快速得到并准确跟踪单惯性测量单元的陀螺零偏。根据本发明的系统,可以根据单惯性测量单元所获取的载体线加速度和角速率信息对天线进行控制；对天线的指向进行校正,保持天线准确地指向卫星,最大限度地保证视频传输的稳定性,提高抗干扰能力。(The invention provides a satellite video transmission system based on an airborne Ka waveband, which comprises: a servo control subsystem comprising an open loop stabilization module, a closed loop tracking module, and a sensor fusion module, wherein: the open-loop stabilization module comprises a single inertia measurement unit, the single inertia measurement unit is used for measuring the linear acceleration and the angular rate of the carrier, and the open-loop stabilization module controls the antenna according to the information of the linear acceleration and the angular rate of the carrier; the closed-loop tracking module corrects the direction of the antenna to keep the antenna accurately directed to the satellite; the sensor fusion module fuses data acquired by a plurality of sensors so as to quickly obtain and accurately track the gyro zero offset of the single inertial measurement unit. According to the system, the antenna can be controlled according to the linear acceleration and angular rate information of the carrier, which are acquired by the single inertia measurement unit; the pointing direction of the antenna is corrected, the antenna is kept to accurately point to the satellite, the stability of video transmission is guaranteed to the maximum extent, and the anti-interference capability is improved.)

1. A satellite video transmission system based on an airborne Ka band, comprising: a servo control subsystem, the servo control subsystem includes an open loop stabilization module, a closed loop tracking module and a sensor fusion module, wherein:

the open-loop stabilization module comprises a single inertia measurement unit, the single inertia measurement unit is used for measuring the linear acceleration and the angular rate of the carrier to obtain the information of the linear acceleration and the angular rate of the carrier, and the open-loop stabilization module is used for controlling the antenna according to the information of the linear acceleration and the angular rate of the carrier obtained by the single inertia measurement unit;

the closed-loop tracking module is used for correcting the pointing direction of the antenna so as to keep the antenna accurately pointed to a satellite;

the sensor fusion module is used for fusing data acquired by the sensors so as to quickly obtain and accurately track the gyro zero offset of the single inertial measurement unit.

2. The system of claim 1, wherein the single inertial measurement unit comprises a number of single axis accelerometers and a number of single axis gyroscopes, the sensor fusion module comprising a velocity sensor, wherein:

the accelerometer is used for detecting acceleration signals of independent three axes of an object in a coordinate system of the carrier and sensing an acceleration component of the airplane relative to a ground vertical line;

the gyroscope is used for detecting an angular velocity signal of the carrier relative to a navigation coordinate system;

the speed sensor is used for sensing the angle information of the airplane, measuring the angle and the acceleration of an object in a three-dimensional space, and calculating the attitude of the object according to the angle and the acceleration of the object in the three-dimensional space.

3. The system of claim 2, wherein the inertial measurement unit is further to:

performing space coordinate transformation on the acceleration signal detected by the accelerometer and the angular velocity signal detected by the gyroscope, and transforming information in a local coordinate system where the accelerometer and the gyroscope are located to corresponding information in a current unified standard space coordinate system;

estimating the attitude information of the carrier by adopting a Kalman filtering algorithm according to corresponding information in the unified standard space coordinate system;

outputting the attitude information of the carrier, the attitude information including an angular rate and an attitude angle.

4. The system of claim 1, wherein the closed loop tracking module comprises a current loop unit, a velocity loop unit, and a position loop unit, wherein,

the current loop unit is used for receiving a current loop given value and a current feedback value and outputting a current loop output value;

the speed loop unit is used for receiving a speed loop set value and a speed feedback value and calculating a current loop set value;

and the position loop unit is used for receiving a position loop set value and a position feedback value and calculating the speed loop set value.

5. The system of claim 4, wherein the current loop unit receives a current loop setpoint and a current feedback value and outputs a current loop output value to perform the steps of:

the current loop unit receives the current loop given value and the current feedback value, and the current loop given value comprises the output of the speed loop unit after PID regulation;

comparing the current loop given value with the current feedback value to obtain a first difference value of the current loop given value and the current feedback value;

and performing PID adjustment on the first difference value in the current loop unit to obtain a first adjustment value, and outputting the first adjustment value to a servo motor, wherein the output of the current loop unit comprises the phase current of each phase of the servo motor.

6. The system of claim 4, wherein the speed loop unit receives a speed loop setpoint and a speed feedback value and calculates the current loop setpoint to perform the steps of:

the speed loop unit receives the speed loop set value and the speed feedback value, and the speed loop set value comprises a second regulation value after PID regulation of the position loop unit;

comparing the speed loop set value with the speed feedback value to obtain a second difference value of the speed loop set value and the speed feedback value;

and carrying out PID (proportion integration differentiation) regulation on the second difference value in the speed loop unit to obtain a third regulating value, and outputting the third regulating value serving as the current loop given value to the current loop unit.

7. The system of claim 6, wherein the position loop unit receives a position loop setpoint and a position feedback value and calculates the velocity loop setpoint by:

the position loop unit receives the position loop set value and the position feedback value, the position loop set value comprises a calculated value obtained by the external pulse signal through smooth filtering processing and electronic gear calculation,

comparing the position loop given value with the position feedback value to obtain a third difference value of the position loop given value and the position feedback value;

and carrying out PID (proportion integration differentiation) regulation on the third difference value in the position ring unit to obtain a second regulation value, and outputting the second regulation value serving as the speed ring set value to the speed ring unit.

8. The system of claim 1, wherein the sensor fusion module fuses data collected by a plurality of sensors to perform the steps of:

acquiring detection data of each sensor at preset time intervals;

performing feature extraction on the data obtained at the current moment, wherein the feature extraction refers to performing time calibration and space coordinate transformation on all detection data at the current moment to form a unified time reference point and a space reference point required by fusion calculation,

wherein the time calibration is based on a time calibration device and a GPS system to realize the time calibration of each sensor, the time calibration device is communicated with the GPS system to obtain time information and provides the time information to each sensor, the time calibration device comprises a processing module, a communication interface and a GPS communication module which is wirelessly communicated with the GPS system,

the step of time calibration comprises: receiving time calibration requests from the sensors, wherein the communication interface waits to receive the time calibration requests from the sensors until receiving the time calibration requests; the communication interface sends a time calibration request from the device to the processing module;

responding to the time calibration request, acquiring time information from the GPS system, controlling the GPS communication module to send the time calibration request by the processing module according to the time calibration request, receiving information returned by the GPS system by the GPS communication module, forwarding the information to the processing module, and extracting the time information or sending the time calibration request again by the processing module;

sending the time information to each sensor, sending the time information to the communication interface by the processing module, starting and interrupting the communication interface to inform each sensor, waiting for the feedback of each sensor, sending the time information to each sensor by the communication interface, and performing time calibration on each sensor;

the step of spatial coordinate transformation includes: calculating a spatial coordinate transformation matrix of each base coordinate system of each sensor relative to a base coordinate system of a first sensor in each sensor, determining a correction parameter of the spatial coordinate transformation matrix of each base coordinate system of each sensor relative to the base coordinate system of the first sensor according to an angle of each sensor at all position points of the corresponding base coordinate system and an angle of the first sensor at all position points of the corresponding base coordinate system, and calculating the spatial coordinate transformation matrix of each base coordinate system of each sensor relative to the base coordinate system of the first sensor according to the correction parameter; carrying out space coordinate transformation on the relative positions of the sensors and the first sensor according to the space coordinate transformation matrix;

respectively performing parameter estimation on the detection data after feature extraction to respectively obtain data estimation of the detection data at the next moment, wherein the parameter estimation is to form a matrix measurement value of a row and N columns on the detection data after feature extraction, and multiplying the deviation between the detection data value at the current moment and the data estimation value at the current moment at the previous moment by a weight number to obtain the data estimation of the detection data at the next moment; simultaneously, carrying out feature identification on the detection data after feature extraction to obtain the feature attribute of the detection data at the current moment, wherein the feature identification is to respectively form an N-dimensional feature vector according to the result of the detection data after feature extraction, and each dimension represents an independent feature of the detection data, so that the feature attribute of the detection data at the current moment is obtained;

respectively carrying out fusion calculation on the next-time data estimation and the current-time characteristic attribute, obtaining a detection data difference of the next-time data estimation and the current-time detection data value, determining the confidence coefficient of the detection data of each sensor, determining a detection deviation estimation value detected by each sensor according to the confidence coefficient and the detection data difference, obtaining an estimation value of the detection data according to the confidence coefficient, the detection deviation estimation value, the next-time data estimation and the current-time detection data value, determining the estimation value of the detection data as the detection data of each sensor, obtaining comprehensive situation estimation of a plurality of sensors, and rapidly obtaining and accurately tracking the gyro zero offset of the single inertial measurement unit according to the comprehensive situation estimation.

9. The system of claim 1, wherein the servo control subsystem further comprises an encoder, a satellite communications antenna, a servo drive module, a calculation module, and a control module, wherein:

the encoder is configured to output a feedback signal to the closed-loop tracking module, the encoder comprising: the device comprises an encoder control unit, an encoder wireless communication unit, an encoder near field communication unit, an encoder power supply unit, a man-machine interaction unit, a clock unit, a positioning unit and an encoder storage unit;

the satellite communication antenna is used for receiving and transmitting Ka waveband communication signals of a geosynchronous orbit communication satellite or a small-inclination-angle geosynchronous orbit communication satellite;

the servo driving module is used for driving the satellite communication antenna to rotate so as to adjust the azimuth angle, the pitch angle and the polarization angle of the satellite communication antenna;

the calculation module is used for calculating an azimuth angle, a pitch angle and a polarization angle required by the satellite communication antenna to be aligned with the target satellite;

the control module is used for controlling the servo driving module to adjust the azimuth angle, the pitch angle and the polarization angle of the satellite communication antenna according to the calculated azimuth angle, the pitch angle and the polarization angle required by the satellite communication antenna to be aligned to the target satellite.

10. The system of claim 1, wherein said closed loop tracking module, in correcting the pointing direction of said antenna to maintain said antenna accurately pointed at a satellite, comprises the steps of;

step A1, determining the receiving feedback power of the antenna according to the input power of the antenna, the wavelength information of the signal wave sent by the antenna, the horizontal antenna angle and the vertical antenna angle;

wherein Pf is the feedback power, χ is the wavelength of the wavelength information, r is the first Fresnel zone radius of the signal emitted by the antenna,

step A2, controlling the horizontal adjustment angle of the antenna according to the linear acceleration and the angular velocity of the carrier;

the psi s is a horizontal adjustment angle of the antenna, arcsin is an inverse trigonometric function sine value, M is a traveling wave coefficient of the carrier, a is the linear acceleration, W is the angular velocity, and v is the linear velocity of the carrier;

step A3, controlling the vertical adjustment angle of the antenna according to the linear acceleration and the angular velocity of the carrier;

wherein ψ c is the vertical adjustment angle, and S is the standing-wave ratio of the carrier;

step a4, adjust the antenna north by ψ s and upward by ψ c to keep the antenna accurately pointed at the satellite.

Technical Field

The invention relates to the technical field of satellite communication, in particular to a satellite video transmission system based on an airborne Ka waveband.

Background

Since the 21 st century, wireless communication has been widely used in many fields such as military affairs, scientific research and human life, and has become an essential communication tool in various aspects such as work, study, entertainment and life. However, as wireless communication is applied to more and more extensive and deeper fields, communication frequency points become more crowded, the requirement for the amount of information of communication becomes greater, the required bandwidth becomes wider and wider, and the currently used wave bands and frequency points cannot meet the requirements more and more. The Ka wave band has strong anti-interference performance, the diameter of the earth station is small, the installation is convenient, and the wider frequency distribution is realized, so that the Ka frequency band satellite communication system has wider application prospect and great potential.

In the moving process of the carrier, because the attitude and the geographic position of the carrier change, the antenna of the original alignment satellite deviates from the satellite, and the communication is interrupted, so the changes of the carrier must be isolated, the antenna is not affected and is always aligned with the satellite, and the main problem to be solved by a satellite video transmission system is the premise that the mobile carrier carries out uninterrupted satellite communication.

Disclosure of Invention

The invention provides a satellite video transmission system based on an airborne Ka wave band, which is used for automatically controlling an antenna according to carrier linear acceleration and angular rate information; and the direction of the antenna is corrected, so that the antenna is kept to be accurately directed to the satellite.

The invention provides a satellite video transmission system based on an airborne Ka waveband, which comprises: a servo control subsystem, the servo control subsystem includes an open loop stabilization module, a closed loop tracking module and a sensor fusion module, wherein:

the open-loop stabilization module comprises a single inertia measurement unit, the single inertia measurement unit is used for measuring the linear acceleration and the angular rate of the carrier to obtain the information of the linear acceleration and the angular rate of the carrier, and the open-loop stabilization module is used for controlling the antenna according to the information of the linear acceleration and the angular rate of the carrier obtained by the single inertia measurement unit;

the closed-loop tracking module is used for correcting the pointing direction of the antenna so as to keep the antenna accurately pointed to a satellite;

the sensor fusion module is used for fusing data acquired by the sensors so as to quickly obtain and accurately track the gyro zero offset of the single inertial measurement unit.

Further, the single inertial measurement unit includes a plurality of single-axis accelerometers and a plurality of single-axis gyroscopes, the sensor fusion module includes a velocity sensor, wherein:

the accelerometer is used for detecting acceleration signals of independent three axes of an object in a coordinate system of the carrier and sensing an acceleration component of the airplane relative to a ground vertical line;

the gyroscope is used for detecting an angular velocity signal of the carrier relative to a navigation coordinate system;

the speed sensor is used for sensing the angle information of the airplane, measuring the angle and the acceleration of an object in a three-dimensional space, and calculating the attitude of the object according to the angle and the acceleration of the object in the three-dimensional space.

Further, the inertial measurement unit is further configured to:

performing space coordinate transformation on the acceleration signal detected by the accelerometer and the angular velocity signal detected by the gyroscope, and transforming information in a local coordinate system where the accelerometer and the gyroscope are located to corresponding information in a current unified standard space coordinate system;

estimating the attitude information of the carrier by adopting a Kalman filtering algorithm according to corresponding information in the unified standard space coordinate system;

outputting the attitude information of the carrier, the attitude information including an angular rate and an attitude angle.

Further, the closed loop tracking module comprises a current loop unit, a velocity loop unit, and a position loop unit, wherein,

the current loop unit is used for receiving a current loop given value and a current feedback value and outputting a current loop output value;

the speed loop unit is used for receiving a speed loop set value and a speed feedback value and calculating a current loop set value;

and the position loop unit is used for receiving a position loop set value and a position feedback value and calculating the speed loop set value.

Further, the current loop unit receives a current loop set value and a current feedback value, and outputs a current loop output value to execute the following steps:

the current loop unit receives the current loop given value and the current feedback value, and the current loop given value comprises the output of the speed loop unit after PID regulation;

comparing the current loop given value with the current feedback value to obtain a first difference value of the current loop given value and the current feedback value;

and performing PID adjustment on the first difference value in the current loop unit to obtain a first adjustment value, and outputting the first adjustment value to a servo motor, wherein the output of the current loop unit comprises the phase current of each phase of the servo motor.

Further, the speed loop unit receives a speed loop set value and a speed feedback value, calculates the current loop set value and executes the following steps:

the speed loop unit receives the speed loop set value and the speed feedback value, and the speed loop set value comprises a second regulation value after PID regulation of the position loop unit;

comparing the speed loop set value with the speed feedback value to obtain a second difference value of the speed loop set value and the speed feedback value;

and carrying out PID (proportion integration differentiation) regulation on the second difference value in the speed loop unit to obtain a third regulating value, and outputting the third regulating value serving as the current loop given value to the current loop unit.

Further, the position loop unit receives a position loop set point and a position feedback value, and calculates the speed loop set point to perform the following steps:

the position loop unit receives the position loop set value and the position feedback value, the position loop set value comprises a calculated value obtained by the external pulse signal through smooth filtering processing and electronic gear calculation,

comparing the position loop given value with the position feedback value to obtain a third difference value of the position loop given value and the position feedback value;

and carrying out PID (proportion integration differentiation) regulation on the third difference value in the position ring unit to obtain a second regulation value, and outputting the second regulation value serving as the speed ring set value to the speed ring unit.

Further, the sensor fusion module fuses data collected by the plurality of sensors and executes the following steps:

acquiring detection data of each sensor at preset time intervals;

performing feature extraction on the data obtained at the current moment, wherein the feature extraction refers to performing time calibration and space coordinate transformation on all detection data at the current moment to form a unified time reference point and a space reference point required by fusion calculation,

wherein the time calibration is based on a time calibration device and a GPS system to realize the time calibration of each sensor, the time calibration device is communicated with the GPS system to obtain time information and provides the time information to each sensor, the time calibration device comprises a processing module, a communication interface and a GPS communication module which is wirelessly communicated with the GPS system,

the step of time calibration comprises: receiving time calibration requests from the sensors, wherein the communication interface waits to receive the time calibration requests from the sensors until receiving the time calibration requests; the communication interface sends a time calibration request from the device to the processing module;

responding to the time calibration request, acquiring time information from the GPS system, controlling the GPS communication module to send the time calibration request by the processing module according to the time calibration request, receiving information returned by the GPS system by the GPS communication module, forwarding the information to the processing module, and extracting the time information or sending the time calibration request again by the processing module;

sending the time information to each sensor, sending the time information to the communication interface by the processing module, starting and interrupting the communication interface to inform each sensor, waiting for the feedback of each sensor, sending the time information to each sensor by the communication interface, and performing time calibration on each sensor;

the step of spatial coordinate transformation includes: calculating a spatial coordinate transformation matrix of each base coordinate system of each sensor relative to a base coordinate system of a first sensor in each sensor, determining a correction parameter of the spatial coordinate transformation matrix of each base coordinate system of each sensor relative to the base coordinate system of the first sensor according to an angle of each sensor at all position points of the corresponding base coordinate system and an angle of the first sensor at all position points of the corresponding base coordinate system, and calculating the spatial coordinate transformation matrix of each base coordinate system of each sensor relative to the base coordinate system of the first sensor according to the correction parameter; carrying out space coordinate transformation on the relative positions of the sensors and the first sensor according to the space coordinate transformation matrix;

respectively performing parameter estimation on the detection data after feature extraction to respectively obtain data estimation of the detection data at the next moment, wherein the parameter estimation is to form a matrix measurement value of a row and N columns on the detection data after feature extraction, and multiplying the deviation between the detection data value at the current moment and the data estimation value at the current moment at the previous moment by a weight number to obtain the data estimation of the detection data at the next moment; simultaneously, carrying out feature identification on the detection data after feature extraction to obtain the feature attribute of the detection data at the current moment, wherein the feature identification is to respectively form an N-dimensional feature vector according to the result of the detection data after feature extraction, and each dimension represents an independent feature of the detection data, so that the feature attribute of the detection data at the current moment is obtained;

respectively carrying out fusion calculation on the next-time data estimation and the current-time characteristic attribute, obtaining a detection data difference of the next-time data estimation and the current-time detection data value, determining the confidence coefficient of the detection data of each sensor, determining a detection deviation estimation value detected by each sensor according to the confidence coefficient and the detection data difference, obtaining an estimation value of the detection data according to the confidence coefficient, the detection deviation estimation value, the next-time data estimation and the current-time detection data value, determining the estimation value of the detection data as the detection data of each sensor, obtaining comprehensive situation estimation of a plurality of sensors, and rapidly obtaining and accurately tracking the gyro zero offset of the single inertial measurement unit according to the comprehensive situation estimation.

Further, the servo control subsystem further comprises an encoder, a satellite communication antenna, a servo driving module, a calculation module and a control module, wherein:

the encoder is configured to output a feedback signal to the closed-loop tracking module, the encoder comprising: the device comprises an encoder control unit, an encoder wireless communication unit, an encoder near field communication unit, an encoder power supply unit, a man-machine interaction unit, a clock unit, a positioning unit and an encoder storage unit;

the satellite communication antenna is used for receiving and transmitting Ka waveband communication signals of a geosynchronous orbit communication satellite or a small-inclination-angle geosynchronous orbit communication satellite;

the servo driving module is used for driving the satellite communication antenna to rotate so as to adjust the azimuth angle, the pitch angle and the polarization angle of the satellite communication antenna;

the calculation module is used for calculating an azimuth angle, a pitch angle and a polarization angle required by the satellite communication antenna to be aligned with the target satellite;

the control module is used for controlling the servo driving module to adjust the azimuth angle, the pitch angle and the polarization angle of the satellite communication antenna according to the calculated azimuth angle, the pitch angle and the polarization angle required by the satellite communication antenna to be aligned to the target satellite.

Further, the closed-loop tracking module comprises the following steps in the process of correcting the pointing direction of the antenna so as to keep the antenna accurately pointed to the satellite;

step A1, determining the receiving feedback power of the antenna according to the input power of the antenna, the wavelength information of the signal wave sent by the antenna, the horizontal antenna angle and the vertical antenna angle;

wherein Pf is the feedback power, χ is the wavelength of the wavelength information, r is the first Fresnel zone radius of the signal emitted by the antenna, θ is the horizontal antenna angle, Rj is the relative dielectric constant of the antenna, and Js is the conductivity of the antenna,

for a preset fluctuation parameter, α is the vertical antenna angle, Ps is the input power, G1 is a preset first power gain, and G2 is a preset second power gain;

step A2, controlling the horizontal adjustment angle of the antenna according to the linear acceleration and the angular velocity of the carrier;

the psi s is a horizontal adjustment angle of the antenna, arcsin is an inverse trigonometric function sine value, M is a traveling wave coefficient of the carrier, a is the linear acceleration, W is the angular velocity, and v is the linear velocity of the carrier;

step A3, controlling the vertical adjustment angle of the antenna according to the linear acceleration and the angular velocity of the carrier;

wherein ψ c is the vertical adjustment angle, and S is the standing-wave ratio of the carrier;

step a4, adjust the antenna north by ψ s and upward by ψ c to keep the antenna accurately pointed at the satellite.

The satellite video transmission system based on the airborne Ka waveband provided by the embodiment of the invention has the following beneficial effects: the antenna can be automatically controlled according to the linear acceleration and angular rate information of the carrier acquired by the single inertial measurement unit; meanwhile, the pointing direction of the antenna can be corrected, the antenna is kept to accurately point to the satellite, the stability of video transmission is guaranteed to the maximum extent, and the anti-interference capability is improved.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

fig. 1 is a block diagram of an airborne Ka-band-based satellite video transmission system according to an embodiment of the present invention.

Detailed Description

The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation.

An embodiment of the present invention further provides a satellite video transmission system based on an airborne Ka band, as shown in fig. 1, including: a servo control subsystem 100, said servo control subsystem 100 comprising an open loop stabilization module 101, a closed loop tracking module 102, and a sensor fusion module 103, wherein:

the open-loop stabilization module 101 comprises a single inertia measurement unit, the single inertia measurement unit is used for measuring the linear acceleration and the angular rate of the carrier to obtain the information of the linear acceleration and the angular rate of the carrier, and the open-loop stabilization module 101 is used for controlling the antenna according to the information of the linear acceleration and the angular rate of the carrier, which is obtained by the single inertia measurement unit;

the closed-loop tracking module 102 is configured to correct the pointing direction of the antenna to keep the antenna pointing to a satellite accurately;

the sensor fusion module 103 is configured to fuse data collected by the plurality of sensors to quickly obtain and accurately track a gyro zero offset of the single inertial measurement unit.

The working principle of the technical scheme is as follows: the open-loop stabilization module 101 controls the antenna according to the carrier linear acceleration and angular rate information acquired by the single inertial measurement unit; the closed-loop tracking module 102 corrects the pointing direction of the antenna to keep the antenna pointing to the satellite accurately; the sensor fusion module 103 is used for fusing data acquired by the plurality of sensors to quickly obtain and accurately track the gyro zero offset of the single inertial measurement unit, so that an error value can be minimized, and the tracking accuracy is improved.

The satellite video transmission system based on the airborne Ka wave band adopts a control scheme of open loop stabilization, closed loop tracking and sensor fusion. The open loop stably controls the antenna by utilizing information provided by a combined measuring unit consisting of a single inertial unit (IMU) so as to isolate the influence of instantaneous disturbance of a carrier on the pointing direction of the antenna. The single inertial unit measures linear acceleration and angular rate information of the carrier. After inertial sensor denoising, attitude estimation algorithm and tracking information gyro error correction, attitude angle and angular rate information can be obtained. The attitude estimation algorithm is adopted to carry out data fusion on different sensors, so that the zero offset of the gyroscope can be quickly obtained and accurately tracked, the influence of the zero offset on attitude estimation is overcome, and meanwhile, an accurate angular velocity signal is given out.

The mechanism of the open-loop stabilization module is an isolation equation, angular rate provided by a single inertia unit is directly projected to an antenna coordinate system for compensation, and the beam is kept to be directed stably in an inertia space. The open loop stabilization module 101 has the advantages of strong autonomy, high update frequency and the like, but the open loop stabilization module 101 completely depends on the accuracy of the sensor. In addition, due to the effects of inertial components, servo drift, and other factors of the system, the antenna beam may gradually deviate from the satellite beam center with the open loop stabilization module 101 alone. The closed-loop tracking module 102 is used for correcting the direction of the antenna, and the antenna is kept to accurately point to the satellite, so that the signal intensity can be kept to be maximum, when a single-antenna GPS/Beidou and the like are interfered, the preset position can be automatically switched in, the information of a double-antenna GPS and Beidou satellite navigation system is not relied on, and the anti-interference capability is very strong.

The beneficial effects of the above technical scheme are: the antenna can be automatically controlled according to the linear acceleration and angular rate information of the carrier acquired by the single inertial measurement unit; meanwhile, the pointing direction of the antenna can be corrected, the antenna is kept to accurately point to the satellite, the stability of video transmission is guaranteed to the maximum extent, and the anti-interference capability is improved.

In one embodiment, the single inertial measurement unit comprises a number of single axis accelerometers and a number of single axis gyroscopes, the sensor fusion module comprises a velocity sensor, wherein:

the accelerometer is used for detecting acceleration signals of independent three axes of an object in a coordinate system of the carrier and sensing an acceleration component of the airplane relative to a ground vertical line;

the gyroscope is used for detecting an angular velocity signal of the carrier relative to a navigation coordinate system;

the speed sensor is used for sensing the angle information of the airplane, measuring the angle and the acceleration of an object in a three-dimensional space, and calculating the attitude of the object according to the angle and the acceleration of the object in the three-dimensional space.

The working principle of the technical scheme is as follows: an inertial measurement unit is a device that measures the three-axis attitude angle (or angular rate) and acceleration of an object. Specifically, an inertial measurement unit comprises three single-axis accelerometers and three single-axis gyros, the accelerometers detect acceleration signals of an object in three independent axes of a carrier coordinate system, the object moves relative to the carrier in the process that the carrier moves along a satellite video transmission system, the gyros detect angular velocity signals of the carrier relative to a navigation coordinate system, the accelerometers are used for sensing acceleration components of the airplane relative to a ground vertical line, and the velocity sensors are used for sensing angle information of the airplane, measuring the angle and the acceleration of the object in a three-dimensional space, and calculating the attitude of the object according to the acceleration components.

The beneficial effects of the above technical scheme are: the attitude of the object can be solved by using an accelerometer, a gyroscope and a velocity sensor.

In one embodiment, the inertial measurement unit is further configured to:

performing space coordinate transformation on the acceleration signal detected by the accelerometer and the angular velocity signal detected by the gyroscope, and transforming information in a local coordinate system where the accelerometer and the gyroscope are located to corresponding information in a current unified standard space coordinate system;

estimating the attitude information of the carrier by adopting a Kalman filtering algorithm according to corresponding information in the unified standard space coordinate system;

outputting the attitude information of the carrier, the attitude information including an angular rate and an attitude angle.

The working principle of the technical scheme is as follows: kalman filtering is a new linear filtering and prediction reason and is characterized in that noisy input and observation signals are processed on the basis of linear state space representation to obtain a system state or a real signal. This theory is expressed in the time domain, and the basic concept is: on the basis of the state space representation of the linear system, an optimal estimate of the state of the system is found from the output and input observation data. The system state, as used herein, is a set of minimum parameters that summarize the effect of all past inputs and disturbances to the system, knowing the state of the system allows the overall behavior of the system to be determined along with future inputs and disturbances to the system.

State estimation is an important component of kalman filtering. Generally speaking, the quantitative inference of random quantities from observed data is an estimation problem, especially for the state estimation of dynamic behavior, which can realize the estimation and prediction functions of real-time operation state. The state estimation has great significance for understanding and controlling a system, and the applied method belongs to estimation theory in statistics. The most common are least squares estimation, linear minimum variance estimation, recursive least squares estimation, etc. Bayesian estimation, maximum likelihood estimation, stochastic approximation, etc. of other risk criteria may also be used.

The noise-disturbed state quantity is a random quantity, it is impossible to measure an exact value, but it can be observed in a series and estimated from some statistical point of view based on a set of observations. The estimated value is made as close as possible to the true value, which is the optimal estimate. The difference between the true value and the estimated value is called the estimation error. If the mathematical expectation of the estimated value is equal to the true value, this estimation is called unbiased estimation. According to the recursion optimal estimation theory provided by Kalman, a state space description method is adopted, a recursion form is adopted in an algorithm, and Kalman filtering can process a multi-dimensional and non-stable random process.

The beneficial effects of the above technical scheme are: and estimating the attitude information of the carrier by using an inertial measurement unit and adopting a Kalman filtering algorithm.

In one embodiment, the closed loop tracking module 102 includes a current loop unit, a velocity loop unit, and a position loop unit, wherein,

the current loop unit is used for receiving a current loop given value and a current feedback value and outputting a current loop output value;

the speed loop unit is used for receiving a speed loop set value and a speed feedback value and calculating a current loop set value;

and the position loop unit is used for receiving a position loop set value and a position feedback value and calculating the speed loop set value.

The working principle of the technical scheme is as follows: the closed-loop tracking module 102 sequentially comprises a current loop unit, a speed loop unit and a position loop unit from inside to outside, wherein the current loop unit receives a current loop set value and a current feedback value and outputs a current loop output value; the speed loop unit receives a speed loop set value and a speed feedback value and calculates a current loop set value; the position loop unit receives the position loop set value and the position feedback value and calculates the speed loop set value. The position loop unit obtains an antenna pointing angle through coordinate conversion by utilizing the carrier attitude provided by the inertia measurement unit, and performs strapdown stabilization on the position loop.

The beneficial effects of the above technical scheme are: by means of the current loop unit, the speed loop unit and the position loop unit, internal time sequence can be guaranteed, various inputs such as weak signals of position, current, speed and the like can be sampled when the output is unchanged, then output signals with strong amplitude can be output at the same moment, the signal strength can be kept to be maximum, and the anti-interference capability can be further improved.

In one embodiment, the current loop unit receives a current loop setpoint and a current feedback value and outputs a current loop output value to perform the following steps:

the current loop unit receives the current loop given value and the current feedback value, and the current loop given value comprises the output of the speed loop unit after PID regulation;

comparing the current loop given value with the current feedback value to obtain a first difference value of the current loop given value and the current feedback value;

and performing PID adjustment on the first difference value in the current loop unit to obtain a first adjustment value, and outputting the first adjustment value to a servo motor, wherein the output of the current loop unit comprises the phase current of each phase of the servo motor.

The working principle of the technical scheme is as follows: the input of the current loop unit is the output of the speed loop unit after PID adjustment, the difference value of the given value of the current loop and the feedback value of the current loop after comparison is output to the motor after PID adjustment in the current loop, wherein the PID adjustment mainly comprises proportional gain and integral processing, the output of the current loop is the phase current of each phase of the motor, and the feedback of the current loop is not the feedback of the encoder but is fed back to the current loop in the driver. The current loop is formed inside the driver, and even without a motor, feedback operation can be formed by only installing an analog load (e.g., light bulb) current loop on each phase.

The beneficial effects of the above technical scheme are: the specific steps of the current loop unit outputting the current loop output value are provided.

In one embodiment, the speed loop unit receives a speed loop setpoint and a speed feedback value and calculates the current loop setpoint to perform the following steps:

the speed loop unit receives the speed loop set value and the speed feedback value, and the speed loop set value comprises a second regulation value after PID regulation of the position loop unit;

comparing the speed loop set value with the speed feedback value to obtain a second difference value of the speed loop set value and the speed feedback value;

and carrying out PID (proportion integration differentiation) regulation on the second difference value in the speed loop unit to obtain a third regulating value, and outputting the third regulating value serving as the current loop given value to the current loop unit.

The working principle of the technical scheme is as follows: the input of the speed loop unit is the output of the position loop unit after PID adjustment and the speed feedback value set by the speed loop unit, the difference value of the speed loop set value and the speed loop feedback value after comparison is subjected to PID adjustment in the speed loop, wherein the PID adjustment mainly comprises proportional gain and integral processing, and then the current loop set value is output. The feedback of the speed loop comes from the feedback value of the encoder and is obtained through the speed arithmetic unit.

The beneficial effects of the above technical scheme are: the specific steps of calculating the given value of the current loop by the speed loop unit are provided.

In one embodiment, the position loop unit receives a position loop setpoint and a position feedback value and calculates the velocity loop setpoint to perform the steps of:

the position loop unit receives the position loop set value and the position feedback value, the position loop set value comprises a calculated value obtained by the external pulse signal through smooth filtering processing and electronic gear calculation,

comparing the position loop given value with the position feedback value to obtain a third difference value of the position loop given value and the position feedback value;

and carrying out PID (proportion integration differentiation) regulation on the third difference value in the position ring unit to obtain a second regulation value, and outputting the second regulation value serving as the speed ring set value to the speed ring unit.

The working principle of the technical scheme is as follows: the input of the position loop unit is a calculated value obtained by smoothing filtering processing and electronic gear calculation of external pulses, the position loop set value and a calculated value of a pulse signal fed back from an encoder through a deviation counter are subjected to PID regulation of the position loop, wherein the PID regulation mainly comprises proportional gain and integral processing, then the speed loop set value is output, and the feedback of the position loop is also from the encoder and is obtained through a position arithmetic unit.

The beneficial effects of the above technical scheme are: the specific steps of the position loop unit calculating a given value of the velocity loop are provided.

In one embodiment, the sensor fusion module 103 fuses the data collected by the sensors to perform the following steps:

acquiring detection data of each sensor at preset time intervals;

performing feature extraction on the data obtained at the current moment, wherein the feature extraction refers to performing time calibration and space coordinate transformation on all detection data at the current moment to form a unified time reference point and a space reference point required by fusion calculation,

wherein the time calibration is based on a time calibration device and a GPS system to realize the time calibration of each sensor, the time calibration device is communicated with the GPS system to obtain time information and provides the time information to each sensor, the time calibration device comprises a processing module, a communication interface and a GPS communication module which is wirelessly communicated with the GPS system,

the step of time calibration comprises: receiving time calibration requests from the sensors, wherein the communication interface waits to receive the time calibration requests from the sensors until receiving the time calibration requests; the communication interface sends a time calibration request from the device to the processing module;

responding to the time calibration request, acquiring time information from the GPS system, controlling the GPS communication module to send the time calibration request by the processing module according to the time calibration request, receiving information returned by the GPS system by the GPS communication module, forwarding the information to the processing module, and extracting the time information or sending the time calibration request again by the processing module;

sending the time information to each sensor, sending the time information to the communication interface by the processing module, starting and interrupting the communication interface to inform each sensor, waiting for the feedback of each sensor, sending the time information to each sensor by the communication interface, and performing time calibration on each sensor;

the step of spatial coordinate transformation includes: calculating a spatial coordinate transformation matrix of each base coordinate system of each sensor relative to a base coordinate system of a first sensor in each sensor, determining a correction parameter of the spatial coordinate transformation matrix of each base coordinate system of each sensor relative to the base coordinate system of the first sensor according to an angle of each sensor at all position points of the corresponding base coordinate system and an angle of the first sensor at all position points of the corresponding base coordinate system, and calculating the spatial coordinate transformation matrix of each base coordinate system of each sensor relative to the base coordinate system of the first sensor according to the correction parameter; carrying out space coordinate transformation on the relative positions of the sensors and the first sensor according to the space coordinate transformation matrix;

respectively performing parameter estimation on the detection data after feature extraction to respectively obtain data estimation of the detection data at the next moment, wherein the parameter estimation is to form a matrix measurement value of a row and N columns on the detection data after feature extraction, and multiplying the deviation between the detection data value at the current moment and the data estimation value at the current moment at the previous moment by a weight number to obtain the data estimation of the detection data at the next moment; simultaneously, carrying out feature identification on the detection data after feature extraction to obtain the feature attribute of the detection data at the current moment, wherein the feature identification is to respectively form an N-dimensional feature vector according to the result of the detection data after feature extraction, and each dimension represents an independent feature of the detection data, so that the feature attribute of the detection data at the current moment is obtained;

respectively carrying out fusion calculation on the next-time data estimation and the current-time characteristic attribute, obtaining a detection data difference of the next-time data estimation and the current-time detection data value, determining the confidence coefficient of the detection data of each sensor, determining a detection deviation estimation value detected by each sensor according to the confidence coefficient and the detection data difference, obtaining an estimation value of the detection data according to the confidence coefficient, the detection deviation estimation value, the next-time data estimation and the current-time detection data value, determining the estimation value of the detection data as the detection data of each sensor, obtaining comprehensive situation estimation of a plurality of sensors, and rapidly obtaining and accurately tracking the gyro zero offset of the single inertial measurement unit according to the comprehensive situation estimation.

The working principle of the technical scheme is as follows: the sensor fusion module 103 includes an inertial sensor, an angle sensor, a speed sensor, an infrared distance measurement sensor, and the like. The current-time characteristic attribute may include, for example, a time at which the inspection data is acquired, a time difference between the next time and the current time, and the like.

The preset time may be 0.1s-1s, for example, may be set to 0.2 s. In the present invention, the detection data obtained by each sensor includes both data layer information and feature layer information. In kalman filtering, the above-mentioned weight number is constantly changing, the weight being related to the deviation of the detected data value from the data estimate at the current time of the previous time. The feature identification is to perform feature layer information fusion on the detection data of each sensor. And the fusion calculation is to verify, analyze, supplement the selection, modification and state tracking estimation on the N-column matrix measurement values and the relevant observation results of the N-dimensional eigenvectors output by the parameter estimation and feature identification part, analyze and synthesize the irrelevant observation results, and obtain the comprehensive situation estimation of gyro zero-bias perception of the single-inertia measurement unit.

The beneficial effects of the above technical scheme are: the method has the advantages that the specific steps of fusing the data acquired by the sensors by the sensor fusion module are provided, comprehensive detection information is obtained, the information returned by the sensors is processed by adopting a multi-sensor fusion mode, accurate gyro zero-offset data of the single inertial measurement unit can be obtained, and the detection accuracy is greatly improved.

In one embodiment, the servo control subsystem 100 further comprises an encoder 104, a satellite communication antenna 105, a servo drive module 106, a calculation module 107, and a control module 108, wherein:

the encoder 104 is configured to output a feedback signal to the closed-loop tracking module 102, and the encoder 104 includes: the device comprises an encoder control unit, an encoder wireless communication unit, an encoder near field communication unit, an encoder power supply unit, a man-machine interaction unit, a clock unit, a positioning unit and an encoder storage unit;

the satellite communication antenna 105 is used for receiving and transmitting Ka-band communication signals of a geosynchronous orbit communication satellite or a small-inclination-angle geosynchronous orbit communication satellite;

the servo driving module 106 is configured to drive the satellite communication antenna to rotate so as to adjust an azimuth angle, a pitch angle, and a polarization angle of the satellite communication antenna;

the calculation module 107 is configured to calculate an azimuth angle, a pitch angle, and a polarization angle required by the satellite communication antenna to be aligned with the target satellite;

the control module 108 is configured to control the servo driving module 106 to adjust the azimuth, the pitch angle, and the polarization angle of the satellite communication antenna according to the calculated azimuth, the pitch angle, and the polarization angle required by the satellite communication antenna 105 to align with the target satellite.

The working principle of the technical scheme is as follows: the velocity feedback value and/or the position feedback value are from the encoder 104. The encoder is arranged at the tail part of the servo motor, is not in any connection with the current loop, samples the rotation of the motor but not the motor current, is not in any connection with the input, the output and the feedback of the current loop, and the main shaft of the encoder is connected with the output shaft of the motor. The motor is a two-phase hybrid stepping motor.

The encoder power supply unit is respectively connected to the encoder control unit, the encoder wireless communication unit, the encoder near field communication unit, the human-computer interaction unit, the clock unit, the positioning unit and the encoder storage unit and provides working voltage; the encoder control unit is also respectively connected with the encoder wireless communication unit, the encoder near field communication unit, the human-computer interaction unit, the clock unit, the positioning unit and the encoder storage unit for information interaction; the encoder near field communication unit is used for realizing near field communication; the encoder wireless communication unit is used for realizing wireless two-way communication; the positioning unit is used for positioning to obtain the positioning information of the encoder at the moment.

The satellite communication antenna 105 receives and transmits a Ka-band communication signal of a geosynchronous orbit communication satellite or a small-inclination-angle geosynchronous orbit communication satellite; the servo driving module 106 drives the satellite communication antenna to rotate so as to adjust the azimuth angle, the pitch angle and the polarization angle of the satellite communication antenna; the calculation module 107 calculates an azimuth angle, a pitch angle and a polarization angle required by the satellite communication antenna to be aligned with the target satellite; the control module 108 controls the servo driving module 106 to adjust the azimuth, the pitch angle and the polarization angle of the satellite communication antenna according to the calculated azimuth, the pitch angle and the polarization angle required for the satellite communication antenna 105 to be aligned with the target satellite.

The beneficial effects of the above technical scheme are: by means of the encoder, a speed feedback value and a position feedback value may be provided; by means of the satellite communication antenna, the servo driving module, the calculating module and the control module, the satellite tracking precision of the satellite communication antenna can be improved.

In a specific embodiment, the closed-loop tracking module comprises the following steps in the process of correcting the pointing direction of the antenna to keep the antenna accurately pointed to the satellite;

step A1, determining the receiving feedback power of the antenna according to the input power of the antenna, the wavelength information of the signal wave sent by the antenna, the horizontal antenna angle and the vertical antenna angle;

wherein Pf is the feedback power, χ is the wavelength of the wavelength information, r is the first Fresnel zone radius of the signal emitted by the antenna, θ is the horizontal antenna angle, Rj is the relative dielectric constant of the antenna, and Js is the conductivity of the antenna,

for a preset fluctuation parameter, α is the vertical antenna angle, Ps is the input power, G1 is a preset first power gain, and G2 is a preset second power gain;

wherein the horizontal antenna angle is an included angle between the antenna and the due north direction, the vertical antenna angle is an angle between the antenna and the horizontal plane,

preset values of between 0 and 1, typically 0.75, G1, G2 preset values of positive number less than 2, and G1+ G2 equal to 2;

step A2, controlling the horizontal adjustment angle of the antenna according to the linear acceleration and the angular velocity of the carrier;

the psi s is a horizontal adjustment angle of the antenna, arcsin is an inverse trigonometric function sine value, M is a traveling wave coefficient of the carrier, a is the linear acceleration, W is the angular velocity, and v is the linear velocity of the carrier;

step A3, controlling the vertical adjustment angle of the antenna according to the linear acceleration and the angular velocity of the carrier;

wherein ψ c is the vertical adjustment angle, and S is the standing-wave ratio of the carrier;

step a4, adjust the antenna north by ψ s and upward by ψ c to keep the antenna accurately pointed at the satellite.

For example, if ψ s is 3 ° and ψ c is 5 °, the antenna is adjusted 3 ° to the north and 5 ° to the top.

The beneficial effects of the above technical scheme are: by utilizing the technology, the direction of the antenna can be determined according to the linear acceleration and angular rate information of the carrier, so that the direction of the antenna is corrected to keep the antenna accurately pointed to the satellite, and meanwhile, by utilizing the technology, the information of the carrier and the antenna can be monitored in real time in the moving process of the carrier, so that the antenna can be regulated and controlled in real time, the antenna can be always aligned to the satellite, and the main problem of a video transmission system can be solved.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.