KR20090014612A - Tracking antenna system for uav and method for controlling the same - Google Patents

Abstract

A tracking antenna system for an unmanned aerial vehicle and a controlling method thereof are provided to improve tracking performance of the tracking antenna by using an image sensor and estimating location of a target on a screen within a tracked range through GPS(Global Positioning System). A GPS processing module(22) receives GPS information related to a mover(20) and an antenna(21) and outputs information required for calculation of a directivity angle of the antenna. A PCU(Pedestal Control Unit)(23) calculates a directivity angle by using an image from an image sensor installed at the antenna and a GPS coordinate information relates to the mover and the antenna from the GPS processing module, and produces an antenna driving instruction. An antenna driving unit drives the antenna in accordance with the driving instruction from the PCU.

Description

Tracking antenna system for unmanned aerial vehicle and its control method {Tracking Antenna System for radio and method for controlling the same}

The present invention relates to a tracking antenna system. Specifically, within a range tracked through a GPS (Global Positioning System), the tracking performance of the antenna can be improved by estimating the position of a target that has entered a screen using an image sensor. A tracking antenna system for an unmanned aerial vehicle and a control method thereof.

In addition to the continuing demand for advanced technologies for unmanned aerial vehicle systems, the interest in communication systems of unmanned aerial vehicle systems is also increasing.

Accordingly, the interest in communication system systems to secure more stable and accurate mission data has shifted to the interest in antennas, which play a pivotal role in communication systems. In addition, the need for a tracking antenna for stable data collection is increasing, and accordingly, a high performance tracking antenna is required.

In particular, in the case of a far-field antenna, the direction of the directional antenna is not large, but when the distance is changed to a short distance, the direction of the antenna is increased. That is, since the near field tracking antenna is clearly distinguished from the existing characteristics, the configuration of the antenna system is required.

Hereinafter, an unmanned aerial vehicle system, a tracking antenna system, and an unmanned aerial vehicle tracking antenna will be described.

The unmanned aerial vehicle system can be roughly classified into an unmanned aerial vehicle, a ground control system (GCS), and a communication system. Among them, the communication system is directly related to data collection.

Data collection is centered around the antenna, and its performance will soon determine its mission. As the mission equipment of the drone increases, so does the amount of information gained.

In addition, mobile wireless communication refers to wireless communication for transmitting and receiving information to and from a moving vehicle such as an aircraft or a ship vehicle. Unlike the two-way communication in the fixed coordinates, the antenna position stabilization device for the movement of the mobile device and the signal fit between the mobile devices are suitable. It is designed by considering all related matters such as tracking, conditions suitable for moving objects, conditions of radio wave transmission, conditions required for communication system, and environmental conditions.

Since 1980, research institutes in advanced countries such as the US, Japan, and Europe have been investing in the development of active antenna systems as the core technology in satellite mobile communication, digital satellite broadcasting service, satellite communication and other satellite mobile services. .

In the research for commercialization in these studies, the development of an active antenna for a commercial satellite system or a mobile satellite communication service for a stationary satellite reception-only service is common, and in particular, in consideration of economics and marketability, an active antenna technology for satellite broadcasting reception is studied. It is becoming.

And the area of unmanned aerial vehicle systems is becoming widespread and specialized, and the most important aspect of such unmanned aerial vehicle systems is information acquisition. Since drones primarily aim for reconnaissance and surveillance, data must be transferred to ground control systems. Since the core of such a communication system depends on the antenna receiving the information, the performance of the antenna is directly related to the information acquisition.

However, in unmanned aerial vehicle systems operating at close range, omni-directional antennas or directional tracking antennas using signal strength (AGC) are used. In the case of non-directional antennas, signals are weakly received, and in the case of tracking antennas using signal strength, short-range flight is performed. Does not have good tracking performance.

In addition, most of the antennas actually used are satellite tracking antennas for satellite broadcasting. The satellite tracking antennas, such as long-range antennas, can direct satellites with little movement, and the driving speed for directing them is not fast. Therefore, satellite tracking antennas aim at the antennas using the radio wave strength from satellites.

However, such tracking antennas cannot be used for unmanned aerial vehicles with different tracking environmental conditions.

Therefore, in order to solve this problem, an antenna tracking method of a moving object using GPS has been used.

In the case of using GPS as described above, errors due to other environmental factors can be minimized. If the exact coordinates between the antenna and the moving object are known, the accuracy of the antenna orientation can be improved.

However, the method using GPS has problems of altitude error and limited GPS data update rate.

The present invention is to solve the problem that it is difficult to use the tracking antenna using the position information of the prior art for the unmanned aerial vehicle, within the range tracked through the GPS, using the image sensor to position the target on the screen An object of the present invention is to provide a tracking antenna system for an unmanned aerial vehicle and a control method thereof, which can increase tracking performance of the antenna by estimating.

The present invention solves the problems of the omnidirectional antenna and the directional tracking antenna of the prior art by using the GPS method, and image processing using the image sensor to solve the problem of the error value of the altitude of GPS and the limited data update rate of GPS It is an object of the present invention to provide a tracking antenna system for an unmanned aerial vehicle and a method of controlling the same, which are solved by using a Kalman filter.

The present invention solves the problems of the conventional tracking antenna by developing a data link tracking antenna system using a GPS and an image sensor, and uses a low-cost GPS device and a high performance tracking antenna using an image sensor. The present invention aims to provide a tracking antenna system for an unmanned aerial vehicle and a method of controlling the same.

In the unmanned aerial tracking antenna system according to the present invention for achieving the above object, in the unmanned aerial tracking antenna system, the GPS processing module for receiving the GPS information of the moving body and the antenna to transfer the information required for the calculation of the orientation angle of the antenna (GPS Process Module); Pedestal control unit (PCU) for generating an antenna driving command by calculating the direction angle using the image from the image sensor installed in the antenna and the GPS coordinates of the moving object and the antenna received from the GPS processing module; And an antenna driver for driving the antenna by a driving command received from the target device, and using the Kalman filter to calculate the position of the target on the screen using the image sensor within the range tracked through the GPS. It is done.

In the unmanned aerial tracking antenna system according to the present invention for achieving another object, the GPS processing module for receiving the GPS information of the moving body and the antenna receives the GPS processing module for transmitting the information necessary for calculating the orientation angle of the antenna ( GPS Process Module); PCU (Pedestal control unit) for generating an antenna drive command by calculating the direction angle using the image from the image sensor installed in the antenna and the GPS coordinates of the moving object and the antenna received from the GPS processing module; PID controller for controlling the antenna drive motor by a signal input through an adder for calculating a drive command value and a drive angle value fed back, a stepper motor for driving the antenna under control of the PID controller, and a stepper motor for driving the stepper motor. Measures the rotation step of the tracking antenna whose drive angle is controlled and the drive angle output value fed back It includes a step count unit, a drive angle measuring unit for receiving the output of the step count unit to measure the antenna drive angle and outputs a drive angle value, the antenna driver for driving the antenna by a drive command received from the PCU; It is done.

In the unmanned aerial tracking antenna system according to the present invention for achieving another object, the GPS processing module for receiving the GPS information of the moving body and the antenna receives the GPS processing module for transmitting the information necessary for calculating the orientation angle of the antenna ( GPS Process Module); PCU (Pedestal control unit) for generating an antenna drive command by calculating the direction angle using the image from the image sensor installed in the antenna and the GPS coordinates of the moving object and the antenna received from the GPS processing module; PID controller for controlling the antenna drive motor by a signal input through an adder for calculating a drive command value and a drive angle value fed back, a DC motor for driving the antenna under control of the PID controller, and a drive for the DC motor. A tracking antenna whose driving angle is controlled by the driving antenna, an optical flow measuring unit for calculating the optical flow from the entire image, and an optical flow To receive the output of the state measuring the antenna driving each comprising a drive to each measurement output of each drive value, and the antenna driving section for driving the antenna by the driving command received from the PCU; characterized in that it comprises a.

According to another aspect of the present invention, there is provided a method for controlling an unmanned aerial vehicle tracking antenna system, the method comprising: receiving GPS location information, obtaining an image, and determining whether a GPS signal has been received. Setting a region of interest in an acquired image according to whether a GPS signal is received; determining whether moving object tracking is possible in the acquired image; calculating a direction angle according to whether GPS is received and whether the image can be traced Outputting a driving command;

According to another aspect of the present invention, there is provided a control method of a tracking antenna system for an unmanned aerial vehicle, in the control of an unmanned aerial tracking antenna system, receiving GPS position information, obtaining an image, and checking whether there is a tracking object in the acquired image. Compensating an antenna driving command by measuring the optical flow of the entire screen, if there is no tracking object in the acquired image, estimating the antenna rotation angle; If there is a tracking object in the acquired image, GPS signal Setting a region of interest in the acquired image according to whether or not to receive; determining whether moving object tracking is possible in the acquired image; calculating an orientation angle according to whether GPS is received and whether the image can be tracked, and performing an antenna driving command. Outputting; characterized in that to perform.

The tracking antenna system for an unmanned aerial vehicle and its control method according to the present invention as described above has the following effects.

First, within the range tracked through the GPS, the tracking performance of the antenna can be improved by estimating the position of the target on the screen using the image sensor.

Second, the tracking performance of the antenna can be improved by solving the problem of the error value of GPS altitude and the limited data update speed of GPS using image processing and Kalman filter using image sensor.

Third, the data link tracking antenna system using GPS and image sensor is developed to solve the problems of the tracking antenna of the previous technology, using low-cost GPS equipment, and using a high-performance tracking antenna using image sensor. It has the effect of being able to design / manufacture.

Hereinafter, a preferred embodiment of the unmanned aerial tracking antenna system and its control method according to the present invention will be described in detail.

Features and advantages of the tracking antenna system for an unmanned aerial vehicle and its control method according to the present invention will become apparent from the detailed description of each embodiment below.

1 is a configuration diagram of an antenna system using a GPS and an image sensor according to the present invention, Figure 2 is a detailed configuration diagram of a tracking antenna system according to the present invention.

The tracking antenna system for the unmanned aerial vehicle and its control method according to the present invention solve the problem of the error value of the altitude of GPS and the limited data update rate of GPS by using image sensor and image processing and Kalman filter. To increase the tracking performance.

In the tracking antenna system for a near unmanned aerial vehicle according to the present invention, as shown in FIG. 1, first, by using the GPS in the antenna system to determine the position of the target and the antenna, and to drive and design the antenna to be directed toward the target Secondly, within the range tracked through GPS, the position of the target object entered on the screen using the image sensor is estimated using the Kalman filter, and installed / controlled so that the camera can be driven correctly.

An antenna system installed on a moving object, such as a ship, is generally composed of three parts: an antenna control unit (ACU), a pedestal control unit (PCU), and a stabilized antenna pedastal (SAP). SAP is controlled by sending azimuth and elevation control commands to the PCU.

The SAP is a mechanical part that directs the moving object by directly controlling the azimuth and the altitude angle of the antenna, and the PCU controls the SAP using the azimuth and altitude values received from the ACU.

In the present invention, ACU and PCU are not used separately and do not require SAP because the antenna is installed on the ground.

As shown in FIG. 2, the GPSU module 22 for receiving and processing the coordinates of the unmanned aerial vehicle 20 and the antenna 21 and the PCU for calculating the direction angles of the antenna 21 and controlling the antenna drive system ( 23) and a PC 24 for monitoring.

The location information output from the GPS is WGS84 longitude latitude coordinate system divided into 180 ° equator and 90 ° north-south to the east and west of England and is expressed using degree, minute: °, '. However, when used in the extent that the distortion of the earth's sphere can be ignored, it is common to convert it to a rectangular coordinate system.

3A and 3B are diagrams for explaining a coordinate system and an orientation angle of an antenna used for calculating a position of a tracking antenna system according to the present invention.

In order to convert the longitude and latitude coordinate system into a Cartesian coordinate system, the earth projection type is used. However, in the present invention, in order to reduce the load of the antenna controller, the center of the antenna is installed around the point where the antenna is installed as shown in FIG. The direction angle is determined by deriving Equation 1 from the geometric positional relationship between the antenna and the moving object as shown in FIG.

The controller of the antenna consists of three parts. The GPS process module receives the GPS information of the moving object and the antenna and transmits the information necessary for calculating the antenna's directing angle to the PCU, and the GPS coordinates of the moving object and the antenna received from the GPS processing module. The PCU calculates a direction angle and generates a motor drive command, and a motor driver, that is, an antenna driver, which drives the motor of the antenna from the command received from the PCU.

And the PID controller is used as a controller of the motor for antenna control, and the motor is driven using the change amount of the speed of the motor as a control input.

Here, e is an error, Ψ cal is the calculated direction of the antenna, Ψ ant is the direction of the antenna, n is a positive integer, and T is the sampling time.

The gain of the PID controller can be obtained analytically by obtaining system modeling, but if the system is not modeled, the gain can be determined through several tests.

And an image based tracking antenna system will be described.

3C is an image histogram for extracting feature points for image-based extraction.

Feature point extraction is essential for tracking objects using images. In general, in order to find a feature point, an image is converted into a binary space using the brightness feature of the ROI. In particular, the binarization method using boundary values occupies a central position in image segmentation and object recognition because of its intuitive properties and simplicity of implementation.

The image histogram as shown in FIG. 3C has a brightness level in which the pixels of the object and the background are clustered in two dominant modes, from the background when the image corresponds to an image f (x, y) composed of bright objects on a dark background. One obvious way to extract an object is to choose a threshold T that separates these two modes.

Here, all points (x, y) in which f (x, y) ≥T are referred to as object points, otherwise referred to as background points. The threshold image g (x, y) is defined as follows.

Pixels labeled 1 correspond to an object and pixels labeled 0 correspond to a background. If T is set to a constant, this method is called global thresholding.

One way to select the threshold is to visually observe the image histogram. Since the image histogram of FIG. 3C clearly has two distinct modes, it is easy to select the boundary value T separating them.

Another way to select T is by trial and error, which changes the threshold until the observer's judgment yields good results. This is particularly effective in an interactive environment where the user can change the thresholds and see the results immediately using graphical controls such as sliders.

In order to select the boundary automatically, the following iterative process can be performed simply.

① Estimate the initial value of T.

② Split the image by T. The result is divided into two groups of pixels of the G ₂ made up of the brightness value of the pixels ≥T G ₁ and the brightness value of a pixel consisting of ≤T.

Calculate the mean values μ ₁ and μ ₂ of the brightness of the pixels for the regions G ₁ and G ₂ .

④ Calculate the new boundary value.

⑤ Repeat steps 2 to 4 until the change in T is less than the predefined parameter T ₀ in successive iterations.

In order to increase the robustness of the boundary value selected by the above method, a method of binarizing an image is applied.

When binarizing the entire image, a large amount of calculation occurs, which causes a problem of slowing down the processing speed. Since the size of the drone, which is to be tracked in the actual image, is very small, the ambient noise has a great influence on the feature extraction and the tracking of the drone.

Therefore, in the present invention, the feature point is extracted by binarizing only a predetermined area at an expected point of the drone.

In this way, the characteristics of the unmanned aerial vehicle are extracted and image coordinates are obtained for image tracking. The coordinates of the pixels that are zero in the ROI are summed and averaged.

Hereinafter, image tracking using a Kalman filter will be described.

4A and 4B are diagrams for explaining in detail the coordinate system and the image coordinate system of the tracking antenna system according to the present invention.

The present invention is based on a tracking antenna system for a GPS-based unmanned aerial vehicle, and uses an image sensor to solve the problem of the control cycle according to the data update speed of the GPS when the unmanned aerial vehicle is approaching close.

In the control cycle problem, the image sensor generally has a data update rate of 30 Hz, which is a great advantage when used together.

In addition, due to the nature of the image processing, it is difficult to accurately track the noise due to the surrounding noise and the Kalman filter can be used to estimate the position of the drone in the image for fast antenna control. To do this, image information is required along with the coordinate information of the antenna and the drone, and a camera and an image acquisition board are required to obtain the image information.

In addition, a related program is required for visual synchronization and calculation between image information and GPS data, and the configuration of an antenna system driven by using the same is shown in FIG. 1.

Such an unmanned aerial vehicle tracking process using the tracking antenna system according to the present invention will be described.

In the unmanned aerial vehicle tracking method of the tracking antenna, the unmanned aerial vehicle is first tracked based on GPS, and the position of the unmanned aerial vehicle in the image is estimated using the azimuth and the altitude angle.

The location of the unmanned aerial vehicle is obtained through a feature extraction algorithm at the position where the unmanned aerial vehicle exists.

If the position of the drone is generated so that the coordinates cannot be in the image, the antenna tracks the drone based on GPS.

When the feature points of the drone are extracted from the location of the unmanned aerial vehicle, the image coordinates are estimated through the Kalman filter, and the control values of the azimuth and elevation angles of the antenna are calculated using the estimated values.

  Coordinate system definition is required for tracking an unmanned aerial vehicle in an image, and the overall system coordinate system is as shown in FIG. 4A.

Where the subscript i denotes the reference coordinate system and the subscript a denotes the antenna coordinate system.

It is more convenient to control the tracking antenna by using the latitude, longitude, and altitude of the GPS than using the actual distance of the antenna.

The azimuth is expressed as Ψ, Ψ _{v / a} is the azimuth of the unmanned aerial vehicle with respect to the antenna coordinates,

_{V / i} represents the azimuth of the unmanned aerial vehicle with respect to the reference coordinate system, and Ψ _{a / i} represents the azimuth of the tracking antenna with respect to the reference coordinate system.

Also, θ means elevation angle, θ _{v / a} is the altitude angle of the unmanned aerial vehicle with respect to the antenna coordinates, θ _{v / i} is the azimuth angle of the unmanned aerial vehicle with respect to the reference coordinate system, and θ _{a / i} is the tracking antenna relative to the reference coordinate system Indicates an elevation angle of. Using this, the equations for azimuth and elevation are as follows:

In addition, an image coordinate system should be defined in order to extract feature points from the image coordinates using the azimuth and elevation angles of the unmanned aerial vehicle with respect to the reference coordinate system, as shown in FIG. 4B.

f is the focal length, and the camera used in the present invention is a CCD camera, and the distance between the camera lens and the sensor of the camera is defined as the focal length. The focal length depends on the zooming function of the camera, and if the image plane is farther away, the image size of the drone in the image increases, and the focal length also increases. As shown in FIG. 4B, the image coordinate axis was determined by the direction of the lens, and the axis was placed upward of the camera. The coordinate system in the image is the origin of the upper left corner of the image.

를 구할 수 있다.3D coordinates between the center point p of the tracking object and the camera through the relationship between the image coordinates and the camera coordinate system of FIG. 4B

Can be obtained.

Using this to find the equation,

Here, (u _p , v _p ) is the coordinate in the image, and (u _c , v _c ) is the center coordinate of the image.

As shown in FIG. 4B, it can be seen that the angle of the drone with respect to the antenna coordinate system is the same as the angle of the drone image with respect to the camera center. Using this, the image coordinates need to be converted to an angle, and the conversion equation is as follows.

Using Equation 7, it is possible to obtain the drone information in the image from the GPS information, and to determine the range to obtain the image data by obtaining the focal length f.

  In order to construct a Kalman filter, an unmanned aerial vehicle model and actual measured information are required in the image, and the position of the unmanned aerial vehicle can be estimated by extracting the feature points, and the position of the unmanned aerial vehicle of the next frame can be estimated through the dynamic model. .

In creating a dynamic model of the drone, the drone is actually moving in three-dimensional coordinates, but in the image it is moving in a two-dimensional plane. Therefore, we use the position-velocity linear model that considers only the position and velocity of the drone in the image.

Hereinafter, a specific embodiment of a tracking antenna system for an unmanned aerial vehicle and a control method thereof according to the present invention will be described.

5 is a configuration diagram of an antenna driving unit of the tracking antenna system for an unmanned aerial vehicle according to the first embodiment of the present invention, Figure 6 is a flow chart for the control of the tracking antenna system for an unmanned aerial vehicle according to the first embodiment of the present invention to be.

First, the tracking antenna system for an unmanned aerial vehicle and its control method according to the first embodiment of the present invention will be described in detail.

The overall configuration of the tracking antenna system for an unmanned aerial vehicle according to the first embodiment of the present invention receives GPS information of a moving object (unmanned aerial vehicle and a target) and an antenna, and performs GPS processing for transmitting the information required for calculating the antenna's direction angle to the PCU. A PCU which calculates the direction angle and generates the antenna drive command using the GPS Process Module, the image from the image sensor installed in the antenna and the GPS coordinates of the moving object and the antenna received from the GPS processing module, and the PCU received from the PCU. It consists of an antenna driver for driving the motor of the antenna from the command.

5 illustrates a detailed configuration of the antenna driver of the tracking antenna system, and includes a PID controller 50 for controlling the antenna driving motor by a signal input through an adder for calculating a driving command value and a driving angle value fed back. ), The step motor 51 driving the antenna under the control of the PID controller 50, the tracking antenna 52 whose drive angle is controlled by the driving of the step motor 51, and the drive angle output value fed back. And a driving angle measuring unit 54 which receives the output of the step counting unit 53 and measures the antenna driving angle to output the driving angle value.

And the control using the tracking antenna system for an unmanned aerial vehicle according to the first embodiment of the present invention is performed as follows.

First, the position information of the unmanned aerial vehicle is received from the GPS, and an image of the direction the antenna is directed to is obtained by a camera mounted on the antenna.

And since the data update rate of GPS is 5Hz and the data update rate of the image is 30Hz, the direction angle calculation method is different depending on the reception of GPS data.

First, when GPS data is received, first, geometrical expressions are applied from GPS location information when image tracking is impossible.

Second, when the image tracking is enabled, the final control command is output by adding the direction angle determined by the geometric relationship calculated by the GPS position information and the direction angle obtained by the image coordinate relationship.

In the case where GPS data reception is impossible, first, when the image tracking is possible, the orientation angle is determined using only the image coordinate relationship.

Second, when image tracking is not possible, the position of the UAV is predicted by using the Kalman filter to estimate the position of the UAV.

Specifically, as shown in FIG. 6, first, GPS location information is received and an image is obtained (S601), and it is determined whether a GPS signal is received (S602).

If the GPS signal is received, the antenna driving command is input as follows.

Image coordinates are predicted (S603), and a region of interest is set in the image (S604).

Then, it is determined whether the image tracking is possible (S605), and if the image tracking is possible, the orientation angle is calculated by adding the GPS information and the image information (S606).

If image tracking is impossible, the orientation angle is calculated using the GPS information (S607).

After the calculation of the orientation angles as described above, a command for driving the antenna is input to the antenna driver (S608).

If the GPS signal is not received, the antenna driving command is input as follows.

A region of interest is set in the image (S609), and it is determined whether image tracking is possible (S610).

If image tracking is impossible, the position of the UAV is predicted based on the GPS information (S611), and a direction angle for driving the antenna is calculated (S613).

If image tracking is possible, image tracking and coordinates are calculated (S612), and an orientation angle for driving an antenna is calculated (S613).

After the calculation of the orientation angles as described above, a command for driving the antenna is input to the antenna driver (S608).

And a tracking antenna system for an unmanned aerial vehicle and a control method thereof according to a second embodiment of the present invention will be described in detail.

7 is a configuration diagram of an antenna driving unit of the tracking antenna system for an unmanned aerial vehicle according to the second embodiment of the present invention, Figure 8 is a flow chart for the control of the tracking antenna system for an unmanned aerial vehicle according to a second embodiment of the present invention to be.

Similarly, the entire configuration of the tracking antenna system for an unmanned aerial vehicle according to the second embodiment of the present invention receives GPS information of a moving object (unmanned aerial vehicle and a target) and an antenna and transmits information necessary for calculating the antenna's directivity angle to the PCU. A PCU that calculates the direction angle and generates the antenna drive command by using the GPS process module, the image from the image sensor installed in the antenna, and the GPS coordinates of the moving object and the antenna received from the GPS processing module, and the PCU. It consists of an antenna driver for driving the motor of the antenna from the command received from.

7 illustrates a detailed configuration of the antenna driver of the tracking antenna system, and includes a PID controller 70 for controlling the antenna driving motor by a signal input through an adder for calculating a driving command value and a driving angle value fed back. ), A DC motor 51 driving the antenna under the control of the PID controller 70, a tracking antenna 72 whose driving angle is controlled by the driving of the DC motor 51, and an optical flow from the entire image. And a driving angle measuring unit 74 which receives the output of the optical flow measuring unit 73 and measures an antenna driving angle to output a driving angle value.

And the control using the tracking antenna system for unmanned aerial vehicle according to the second embodiment of the present invention is performed as follows.

First, the position information of the unmanned aerial vehicle is received from the GPS, and an image of the direction the antenna is directed to is obtained by a camera mounted on the antenna.

And since the data update rate of GPS is 5Hz and the data update rate of the image is 30Hz, the direction angle calculation method is different depending on the reception of GPS data.

Here, when there is no tracking object in the image receiving GPS position information and acquiring the image, the driving command is compensated by measuring the full screen optical flow.

In other words, when GPS data is received, first, geometrical expressions are applied from GPS location information when image tracking is impossible.

Second, when the image tracking is enabled, the final control command is output by adding the direction angle determined by the geometric relationship calculated by the GPS position information and the direction angle obtained by the image coordinate relationship.

In the case where GPS data reception is impossible, first, when the image tracking is possible, the orientation angle is determined using only the image coordinate relationship.

Second, when image tracking is not possible, the position of the UAV is predicted by using the Kalman filter to estimate the position of the UAV.

In the step of receiving the GPS position information and acquiring the image, if there is no tracking object in the image, the driving command is compensated by measuring the full screen optical flow.

Specifically, as shown in FIG. 8, first, GPS location information is received and an image is obtained (S801), and it is determined whether a GPS signal is received (S802).

If the GPS signal is received, the antenna driving command is input as follows.

Image coordinates are predicted (S803), and a region of interest is set in the image (S804).

Then, it is determined whether the image tracking is possible (S805), and if the image tracking is possible, the orientation angle is calculated by adding the GPS information and the image information (S806).

If image tracking is not possible, the orientation angle is calculated using GPS information (S807).

After the calculation of the orientation angle is completed, a command for driving the antenna is input to the antenna driver (S808).

If the GPS signal is not received, enter the antenna driving command as follows.

A region of interest is set in the image (S809), and it is determined whether image tracking is possible (S810).

If image tracking is impossible, the position of the UAV is predicted based on the GPS information (S811), and a direction angle for driving the antenna is calculated (S813).

If image tracking is possible, image tracking and coordinates are calculated (S812), and an orientation angle for driving an antenna is calculated (S813).

After the calculation of the orientation angle is completed, a command for driving the antenna is input to the antenna driver (S808).

In operation S801, when receiving the GPS location information and acquiring the image, when there is no tracking object in the image received from the camera attached to the antenna, the entire light flow of the entire screen is measured.

Subsequently, the average optical flow is estimated (S815), and the antenna rotation angle is estimated using this (S816).

The antenna driving command is compensated using the estimated antenna rotation angle (S817).

As such, the use of a DC motor instead of a step motor as a motor for driving an antenna is intended to reduce the weight of equipment in the system configuration and to increase the driving speed.

The configuration of Figure 7 is a control loop of the structure that can reduce the use of additional equipment while using a DC motor.

The tracking antenna system for the unmanned aerial vehicle and the control method thereof according to the present invention described above use the tracking antenna based on GPS outside the visible range of the image, and improve the performance of the tracking antenna with the help of the image in the near area where the field of view is secured. It can increase.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

1 is a block diagram of an antenna system using a GPS and an image sensor according to the present invention

2 is a detailed configuration diagram of the tracking antenna system according to the present invention

3a and 3b are views for explaining the coordinate system and the orientation angle of the antenna used in the position calculation of the tracking antenna system according to the present invention

3C is an image histogram for extracting feature points for image-based extraction

4a and 4b are views for explaining the coordinate system and the image coordinate system of the tracking antenna system according to the present invention

5 is a configuration diagram of an antenna driving unit of the tracking antenna system for an unmanned aerial vehicle according to the first embodiment of the present invention

6 is a flow chart for controlling the tracking antenna system for an unmanned aerial vehicle according to the first embodiment of the present invention.

7 is a configuration diagram of an antenna driver of the tracking antenna system for an unmanned aerial vehicle according to the second embodiment of the present invention.

8 is a flowchart for controlling a tracking antenna system for an unmanned aerial vehicle according to a second embodiment of the present invention.

Explanation of symbols for the main parts of the drawings

50.70. PID controller 51.step motor

52.72. Tracking Antenna 53. Step Counting Section

54.74. Drive Angle Measuring Unit 71.DC Motor

73. Optical flow measurement unit

Claims (14)

In an unmanned aerial tracking antenna system, A GPS process module for receiving the GPS information of the moving object and the antenna and transmitting information necessary for calculating the direction angle of the antenna; A PCU (Pedestal control Unit) for generating an antenna driving command by calculating a direction angle by using the image from an image sensor installed in the antenna and the GPS coordinates of the moving object and the antenna received from the GPS processing module; And an antenna driver for driving the antenna by a driving command received from the PCU. A tracking antenna system for an unmanned aerial vehicle, characterized in that tracking the target by calculating the position of the target on the screen using a Kalman filter within the range tracked through the GPS. The method of claim 1, wherein the PEDestal control unit (PCU), 12. A tracking antenna system for an unmanned aerial vehicle, the antenna driving command being generated based on the reception of GPS data and the absence of a tracking object in the acquired image. The method of claim 1, wherein the PEDestal control unit (PCU), An antenna driving command is generated based on GPS outside the visible range of an acquired image, and an antenna driving command is generated based on the acquired image in a near area where a field of view is secured. The antenna driver of claim 1, A PID controller for controlling the antenna drive motor by a signal input through an adder for calculating a driving command value inputted and a driving angle value fed back; A step motor for driving the antenna by control of the PID controller, A tracking antenna whose drive angle is controlled by the drive of the stepper motor, A step counting unit for measuring a rotation step of the drive angle output value fed back; And a driving angle measuring unit configured to receive an output of the step count unit and measure an antenna driving angle to output a driving angle value. The antenna driver of claim 1, A PID controller for controlling the antenna drive motor by a signal input through an adder for calculating a driving command value inputted and a driving angle value fed back; A DC motor for driving the antenna by control of the PID controller, A tracking antenna whose drive angle is controlled by the drive of a DC motor; An optical flow measurement unit for calculating an optical flow from an entire image, And a driving angle measuring unit configured to receive an output of the optical flow measuring unit and measure an antenna driving angle to output a driving angle value. In an unmanned aerial tracking antenna system, A GPS process module for receiving the GPS information of the moving object and the antenna and transmitting information necessary for calculating the direction angle of the antenna; A PCU (Pedestal control Unit) for generating an antenna driving command by calculating a direction angle by using the image from an image sensor installed in the antenna and the GPS coordinates of the moving object and the antenna received from the GPS processing module; A PID controller for controlling the antenna drive motor by a signal input through an adder for calculating an input driving command value and a driving angle value fed back, a stepper motor for driving the antenna under control of the PID controller, and a step motor A tracking antenna whose driving angle is controlled by driving, a step counting unit measuring a rotational step of the feedback driving angle output value, and a driving angle measuring unit receiving the output of the step counting unit to measure the antenna driving angle and outputting a driving angle value. And an antenna driver for driving the antenna by a driving command received from the PCU. In an unmanned aerial tracking antenna system, A GPS process module for receiving the GPS information of the moving object and the antenna and transmitting information necessary for calculating the direction angle of the antenna; A PCU (Pedestal control Unit) for generating an antenna driving command by calculating a direction angle by using the image from an image sensor installed in the antenna and the GPS coordinates of the moving object and the antenna received from the GPS processing module; PID controller for controlling the antenna driving motor by a signal input through an adder that calculates an input driving command value and a driving angle value fed back, a DC motor for driving an antenna under control of a PID controller, and a DC motor A tracking antenna for controlling the driving angle by driving, an optical flow measuring unit for calculating an optical flow from the entire image, and a driving angle measuring unit for receiving an output of the optical flow measuring unit to measure an antenna driving angle and outputting a driving angle value; And an antenna driver for driving the antenna by a driving command received from the tracking antenna system for an unmanned aerial vehicle. In the control of an unmanned aerial tracking antenna system, Receiving GPS location information, acquiring an image, and determining whether a GPS signal has been received; Setting a region of interest in the acquired image according to whether a GPS signal is received; Determining whether moving object tracking is possible in the acquired image; And calculating an orientation angle according to whether GPS is received and whether image tracking is possible, and outputting an antenna driving command. In the control of an unmanned aerial tracking antenna system, Receiving GPS location information, acquiring an image, and determining whether there is a tracking object in the acquired image; Compensating an antenna driving command by estimating the antenna rotation angle by measuring the optical flow of the entire screen when there is no tracking object in the acquired image. If there is a tracking object in the acquired image, setting a region of interest in the acquired image according to whether a GPS signal is received; Determining whether moving object tracking is possible in the acquired image; And calculating an orientation angle according to whether GPS is received and whether image tracking is possible, and outputting an antenna driving command. The method according to claim 8 or 9, wherein when the GPS signal is received, the region of interest is set in the image after predicting the image coordinates. If the GPS signal is not received, the method of controlling a tracking antenna system for an unmanned aerial vehicle, characterized in that the region of interest is set in the image without estimating the image coordinates. The method of claim 10, wherein in the state where a GPS signal is received, The control method of the tracking antenna system for an unmanned aerial vehicle, characterized in that if the image tracking is possible to calculate the direction angle by combining the GPS information and the image information. The method of claim 10, wherein in the state where a GPS signal is received, If the image tracking is impossible, the control method of the tracking antenna system for an unmanned aerial vehicle, characterized in that for calculating the direction angle using GPS information. The method of claim 10, wherein in a state in which a GPS signal is not received, If the image tracking is possible, the control method of the tracking antenna system for an unmanned aerial vehicle, characterized in that for calculating the direction angle for driving the antenna by predicting the position of the UAV based on the image information. 10. The method of claim 9, wherein the compensation of the antenna driving command in the absence of the tracking object in the acquired image, Measuring the optical flow of the entire screen of the acquired image; Estimating the average light flow of the measured light flows, And estimating the antenna rotation angle using the estimated average optical flow.

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