Method and device for monitoring flight path guidance parameters in PFD (Personal Frequency Division) picture based on FPGA (Field Programmable Gate Array)

Abstract

The invention provides a method and a device for monitoring flight path guidance parameters in a PFD picture based on an FPGA (Field Programmable Gate Array), which are characterized in that binarization is carried out on the basis of an actual display picture, and a magenta solid circle is identified according to features; and then identifying the slope of a magenta line passing through the magenta solid circle to obtain a horizontal flight guide value. Recognizing a green circle, calculating the distance from the center of the green circle to the center of the magenta realization circle, and obtaining a vertical flight guidance value. And obtaining a deviation angle according to the distance from the magenta solid circle to the perpendicular bisector of the heaven and earth line. The method is realized based on typical pattern and color weight method identification, can effectively resist interference of same-color patterns, improves the identification rate, improves the average fault interval time, and guarantees the flight safety.

Description

Technical Field

[0001] The invention belongs to the field of graphic monitoring, and in particular relates to a method and device for monitoring flight path guidance parameters in a PFD screen based on FPGA. Background Art

[0002] The digital display of an aircraft is an important component for realizing human-computer interaction. The digital display receives parameter information collected by various sensors through the onboard bus and draws it on the display screen through the GPU. The pilot obtains various parameter information of the aircraft through different screens of the digital display. Among them, the PFD screen is responsible for displaying the most important flight parameters, such as airspeed, pressure altitude, pitch angle, roll angle, metric Mach number, and flight path guidance.

[0003] In order to improve the reliability of digital displays and increase the mean time between failures, it is necessary to monitor the display screen output by the GPU. Furthermore, real-time monitoring of the video data stream output by the GPU screen can improve the monitoring confidence. Considering the limited processing resources of the CPU and GPU, the real-time monitoring requirements and the flexibility of programming, the use of FPGA is a very promising method.

[0004] The image frames of the flight path guidance parameters are dynamically moved within the range of the trackball. Therefore, it is necessary to find relevant methods to accurately identify these images. Summary of the invention

[0005] The present invention provides a method and device for monitoring flight path guidance parameters in a PFD screen based on FPGA, so as to realize monitoring of flight path guidance parameters in the PFD screen.

[0006] The first aspect of the present invention provides a method for monitoring flight path guidance parameters in a PFD screen based on FPGA, comprising:

[0007] Get the current PFD screen;

[0008] The PFD screen at the current moment is binarized to obtain a binarized image; the value of the pixel point of the first preset color in the binarized image is the first preset value, the value of the pixel point of the second preset color is the second preset value, and the value of the pixel points of the remaining colors is 0; the first preset color is the color of the symbol of the aircraft in the PFD screen; the second preset color is the color of the symbol of the target in the PFD screen;

[0009] Using a first preset window, starting from the upper left corner of the binary image, traversing the binary image from left to right and from top to bottom, obtaining the sum of the values ​​of all pixel points within the first preset mask range of the first preset window, and taking the center position corresponding to the maximum sum value greater than the first preset threshold as the center point coordinate of the aircraft symbol; obtaining the horizontal flight path according to all pixel points in the binary image whose values ​​are the first preset values ​​and the center point coordinate of the aircraft symbol;

[0010] Using a second preset window, starting from the upper left corner of the binary image, traverse the binary image from left to right and from top to bottom, obtain the sum of the number of all pixel points whose values ​​are the second preset value within the second preset mask range of the second preset window, and take the center position corresponding to the maximum sum of the numbers greater than the second preset threshold as the center point coordinate of the target symbol; according to the center point coordinate of the target symbol and the center point coordinate of the aircraft symbol, obtain the vertical flight path;

[0011] According to the roll angle of the aircraft and the coordinates of the origin of the aircraft in the binary image, the expression of the perpendicular bisector of the sky-ground line in the binary image is obtained; the shortest distance between the center point of the aircraft symbol and the perpendicular bisector of the sky-ground line in the binary image is obtained, and the flight guidance yaw angle is obtained according to the shortest distance;

[0012] The horizontal flight path, vertical flight path and flight guidance yaw angle in the PFD screen are monitored according to the received horizontal flight path, vertical flight path and flight guidance yaw angle values.

[0013] Optionally, the first preset color is magenta or pink, and the second preset color is green; binarizing the PFD screen at the current moment to obtain a binarized image includes:

[0014] Traverse the values ​​of all pixel points in the PFD screen at the current moment. When the value of the pixel point meets the requirements that the red component is greater than or equal to 0xEB, the green component is in the range of 0x23 to 0x41, and the blue component is greater than or equal to 0xEB, then the value of the pixel point is set to the first preset value; when the value of the pixel point meets the requirements that the red component is in the range of 0x5A to 0x6E, the green component is greater than or equal to 0XE6, and the blue component is less than or equal to 0x14, then the value of the pixel point is set to the second preset value, otherwise, the value of the pixel point is 0.

[0015] Optionally, the first preset value is K, and the second preset value is 1; K is a weight multiple.

[0016] Optionally, the first preset mask is a solid circle.

[0017] Optionally, obtaining the horizontal flight path according to all pixel points whose values ​​are the first preset value in the binary image and the coordinates of the center point of the aircraft symbol includes:

[0018] According to all the pixel points with the first preset value in the binary image and the coordinates of the center point of the local symbol, the least squares fitting principle is used to calculate the formula Get the local symbol slope b;

[0019] Determine the horizontal flight path based on the own-ship symbol slope;

[0020] Among them, x i is the difference between the x coordinate of the pixel point with the first preset value and the center point of the local symbol, y i is the difference between the y coordinate of the pixel point whose value is the first preset value and the center point of the local symbol, and n is the number of pixel points whose value is the first preset value.

[0021] According to the slope of the own aircraft symbol, the FD horizontal angle is obtained by looking up the ROLL_ATAN_VAL_ROM module as the horizontal flight path.

[0022] Optionally, the second preset mask is two symmetrical arc segments on the same circular ring.

[0023] Optionally, the vertical flight path is obtained according to the center point coordinates of the target symbol and the center point coordinates of the own aircraft symbol, including:

[0024] Get the distance between the center point of the target symbol and the center point of the own aircraft symbol;

[0025] Obtain the vertical angle value according to the distance and the preset distance-angle conversion coefficient;

[0026] Determine the sign bit of the vertical angle value according to the positional relationship between the center point coordinates of the target symbol and the center point coordinates of the own aircraft symbol;

[0027] Based on the sign bit and the vertical angle value, the vertical flight path is determined.

[0028] A second aspect of the present invention provides a flight path guidance parameter monitoring device in a PFD screen implemented based on FPGA, which is used to execute the method as described in any one of the first aspects.

[0029] The present invention provides a method and device for monitoring flight path guidance parameters in a PFD screen based on FPGA. Based on the actual display screen, binarization is performed, and a magenta solid circle is first identified according to the features; then the slope of the magenta line passing through the magenta solid circle is identified to obtain the horizontal flight guidance value. Then the green circle is identified, and the distance from the center of the green circle to the center of the magenta realization circle is calculated to obtain the vertical flight guidance value. Then, the deviation angle is obtained based on the distance from the magenta solid circle to the perpendicular bisector of the horizon. The present invention is implemented based on typical patterns and color weight method recognition, which can effectively resist the interference of patterns of the same color, improve the recognition rate, increase the mean time between failures, and ensure flight safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic diagram of the flight path guidance display in the PFD screen of the present invention;

[0031] Figure 2 It is a schematic diagram of a magenta solid circle being blocked by green;

[0032] Figure 3 Match the template for magenta;

[0033] Figure 4 Show the scene for the green circle;

[0034] Figure 5 It is a green circle template;

[0035] Figure 6 Schematic diagram of the distance between the magenta circle and the central angle. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0037] The features and illustrative embodiments of various aspects of the present invention will be described in detail below. In the detailed description below, many specific details are proposed to provide a comprehensive understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without the need for some of these specific details. The following description of the embodiments is only to provide a better understanding of the present invention by illustrating examples of the present invention. The present invention is by no means limited to any specific settings and methods proposed below, but covers any improvements, replacements and modifications of structures, methods, devices without departing from the spirit of the present invention. In the accompanying drawings and the following description, known structures and technologies are not shown to avoid unnecessary ambiguity in the present invention.

[0038] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other, and the embodiments can refer to and quote each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0039] The present invention is further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0040] In the present invention, in the actual operating environment, according to the display characteristics of the flight path guidance, the angle between the short line on the magenta solid sphere and the horizontal line represents the horizontal flight path (lateral FD), the length of the line segment between the magenta solid sphere and the center of the green hollow circle represents the vertical flight path (Vertical FD), and the distance from the magenta solid sphere to the perpendicular bisector of the horizon represents the drift angle. The upper left corner is the origin, the horizontal line to the right is the positive axis of the x-axis, and the vertical line downward is the positive axis of the y-axis. The flight path guidance in the PFD is displayed as follows: Figure 1 shown.

[0041] The flight path guidance consists of two symbols:

[0042] 1)FPV symbol: green circle;

[0043] 2) FPD symbol: a solid magenta circle with a line through the center and two hollow triangles with their tips connected to the endpoints of the line.

[0044] Vertical FD:

[0045] The distance from the center of the FPV symbol to the center of the FPD symbol is the vertical FD, which is calculated according to the following formula. If there is a solid magenta circle above the green circle, the vertical FD is positive, otherwise the vertical FD is negative.

[0046] |Vertical FD|=the distance×10 / 91

[0047] Horizontal FD:

[0048] The angle between the magenta line of the FPD symbol and the pfd_coor_x axis is the lateral FD. If the angle from the positive direction of the pfd_coor_x axis to the magenta line of the FPD symbol is an acute angle, the lateral FD is negative, otherwise the lateral FD is positive.

[0049] Yaw angle:

[0050] The distance from the center of the FPD symbol to the median perpendicular of the skyline is the yaw angle, which is calculated as follows: If the solid magenta circle is to the right of the median perpendicular of the skyline, the yaw angle is positive, otherwise the yaw angle is negative.

[0051] |Drift Angle|=the distance×10 / 91

[0052] When the magenta circle or green circle is not detected, the vertical FD angle is invalid. When the magenta circle is not detected, the vertical FD, lateral FD, and yaw angle are all invalid.

[0053] The process of the implementation scheme of the present invention is as follows:

[0054] In the present invention, the FPGA provides a coordinate system, a binary value, and a trigonometric function value of the roll angle according to other modules, performs the function of flight guidance recognition, and outputs the recognition result.

[0055] A) Binarization module

[0056] Binarization is the process of converting the input 24-bit RGB data stream into a double-bit data stream, thereby saving resources and simplifying subsequent data extraction, template matching and other processing processes.

[0057] Image binarization is essentially a filtering algorithm that filters out useless background data and extracts the required feature data. There are many different binarization algorithms. In actual use, different binarization algorithms should be selected according to different application scenarios.

[0058] This article takes the common threshold-based binarization and special color extraction-based binarization as examples to briefly introduce their logical implementation principles.

[0059] In the input 24-bit RGB data, the upper 8 bits represent the red component, the middle 8 bits represent the green component, and the lower 8 bits represent the blue component.

[0060]

[0061] Then, the binarized value is input into the flight guidance recognition module.

[0062] B) Coordinate generation module

[0063] The function of the coordinate generation module is to calculate the position coordinates of each incoming pixel data in the entire image based on the video line, field synchronization signal and data valid signal. Generally, the upper left corner of the image is selected as the coordinate origin. Taking an image of 800×600 as an example, the corresponding relationship between its coordinates and pixel points is as follows: Figure 3 shown.

[0064] The X-axis coordinate coor_x is generated based on the input video data valid signal DE and the pixel clock CLK. The rising edge of DE starts the coor_x count, and during the period when DE is high, coor_x is incremented by 1 at each CLK rising edge and cleared at the falling edge of DE, and so on. For 800×600 video data, each line of video has 800 pixels, so the range of coor_x is [0,799].

[0065] The Y coordinate coor_y is started and cleared at the beginning of each video frame, that is, when the VS signal rises. Then, at the falling edge of each DE, coor_y is incremented by 1 until it is cleared at the rising edge of the next video frame. This cycle repeats. For 800×600 video data, there are 600 lines of valid data, so the range of coor_y is [0,599].

[0066] C) Roll angle calculation

[0067] The present invention directly adopts the trigonometric function of the roll angle calculated by other modules.

[0068] D) Preprocessing module (PFD_RPEPROCESS)

[0069] The FPD_PREPROCESS module implements a pipeline cache of 19 lines of video data. One clock can output 20 lines of video data for calculation. At the same time, it generates the start signal for matching the green circle and the magenta circle, as well as the start signal for calculating the horizontal FD angle, vertical FD angle, and yaw angle according to the input pixel coordinates.

[0070] E) Magenta solid circle calculation

[0071] The MAGENTA_CIRCLE_MATCH module matches the magenta solid circle and outputs the coordinates of the center point of the magenta solid circle and a matching completion flag. The magenta solid circle matching algorithm is a weighted matching algorithm. In this algorithm, 15 lines of image data are input in parallel and accumulated in parallel. The matching algorithm only calculates the pixels within the magenta solid circle, and the pixels outside the magenta solid circle are not included in the calculation range, so the complete solid circle contains a total of 200 points.

[0072] The meaning of weight is that each pixel has a different weight coefficient, as shown in the following table.

[0073]

[0074]

[0075] Therefore, a full solid circle contains 200 points, and the maximum sum of their weighted values ​​is 400. When the magenta circle is blocked (see Figure 2 ), as long as the sum of the weighted values ​​of the magenta solid circles is greater than 280, it is considered that a magenta solid circle is matched successfully. By comparing the weighted values ​​of the magenta solid circles, the best matching result and the coordinates of the magenta solid circles can be found.

[0076] In actual design, according to Figure 3 The template is used to scan and accumulate the 15 rows of data input in parallel in real time to obtain the sum of the digital information of each column in the 15 rows of parallel data. If the sum of the digital information of the current magenta solid circle is greater than the sum of the digital information of the previously recorded magenta solid circle, the digital information and center point coordinates of the current magenta solid circle are recorded. If the sum is less than or equal to the previous record, the recorded digital information and coordinates will not be replaced and updated. (Note: The coordinates of the center point of the magenta solid circle are located in the 8th row and 8th column of the 15 rows of data).

[0077] This module calculates the coordinates of the center point of the magenta solid circle based on the coordinates of the lower left pixel ram_0_dout (row_16, col_16) of the current solid circle in the intercepted area. The radius of the magenta solid circle is 7, so the coordinates of the center point of the magenta solid circle are (row_16-7, col_16+7).

[0078] F) Green circle identification

[0079] The GREEN_CIRCLE_MATCH module matches the green circle and outputs the center coordinates of the green circle and a matching completion flag.

[0080] The matching algorithm for the green circle is a texture shape matching algorithm. Sometimes the green circle background has green pixel interference, such as Figure 4 As shown. In order to improve the matching rate, only the positions of the green pixels of the parallel 20 lines of input data are accumulated. The pixels in the non-green circular area are not included in the calculation range. The 20 lines of pixels of the complete green circle contain a total of 120 points. If 100 points are detected, it is considered that there is a green circle; according to the FPV symbol matching template ( Figure 5), when the number of green pixels in each frame of FPV symbol is equal to or greater than 100, the green circle is considered to be recognized. When the image data is valid, the module calculates the coordinates of the center point of the green circle based on the coordinates of the lower left pixel ram_0_dout(row_16,col_16) of the current calculation circle in the intercepted area. The radius of the green circle is 11, so the coordinates of the center point of the magenta solid circle are (row_16-10,col_16+11).

[0081] G) Horizontal flight path (Lateral FD) calculation

[0082] Store the coordinates (row and column count) of valid pixels of magenta color in FIFO. The FIFO is 1024 deep and 32 bits wide, [27:16] stores column coordinates and [11:0] stores row coordinates. When the pixel data is invalid or the color is not magenta, it will not store the data in FIFO.

[0083] When the coordinates of the center point of the magenta circle are obtained and the magenta circle is determined to be valid, the module starts reading the coordinates of the magenta pixel from the FIFO. If the center point of the magenta circle is not detected, the following calculations will not be implemented.

[0084] The module then determines whether the coordinates of the magenta pixel are valid pixels for line detection, and calculates the slope of the magenta line based on the least squares fitting principle (linear regression model). The calculation formula for the slope of the magenta line is as follows:

[0085]

[0086] Where: x i is the difference between the magenta pixel and the magenta solid circle on the x (row) axis, (y i ) is the difference between the magenta pixel and the magenta solid circle on the y(col) axis. n is the digital sum of all magenta pixels.

[0087] According to the slope of the straight line, the FD horizontal angle is obtained by searching the ROLL_ATAN_VAL_ROM module as the horizontal flight path.

[0088] H) Vertical flight path (Vertical FD) calculation

[0089] When the center point of the magenta circle or the green circle is detected, the difference between the x-axis and y-axis of the straight-line distance between the magenta solid circle and the center point of the green circle is obtained:

[0090] Δx=x magenta -x green

[0091] Δy=y magenta -y green

[0092] After obtaining the difference between the x-axis and the y-axis, the square of the distance d can be obtained using a multiplier. 2 ,

[0093] d 2 =Δx 2 +Δy 2

[0094] Use the SQRT_INT_FRACTION module to find the root d,

[0095]

[0096] In hardware design, the distance d is 16-bit unsigned data, and the last 2 bits are decimals.

[0097] After obtaining the distance d, use the multiplier to convert it to the vertical angle value:

[0098] Vertical_FD=d×10 / 91

[0099] 10 / 91 is a distance / angle conversion method. The distance d is multiplied by 10 / 91 to convert to an angle value, where 10 represents 10 degrees and 91 represents 91 pixels on the screen.

[0100] The sign of the angle value is determined based on the position relationship (row direction) between the magenta circle and the green circle. If the magenta circle is above the green circle, the angle value is positive; otherwise, the angle value is negative.

[0101] I) Drift angle calculation

[0102] Based on the tan value of the roll angle +90° and the coordinates of the center point, the expression of the perpendicular bisector of the sky-ground line is obtained;

[0103] According to the coordinates of the center of the magenta circle, calculate the shortest distance from the center of the solid magenta circle to the perpendicular bisector of the horizon. After obtaining the shortest distance, convert it into an angle value output, that is, the FD yaw angle.

[0104] See Figure 6 , the angle of the center line is equal to the roll angle plus 90 degrees. After obtaining the coordinates of the center point and the sin and cos values ​​of the straight line angle, the module can calculate the coordinates of any point on the center line. Therefore, the module can calculate the distance between the magenta solid circle and the points on the center line one by one, and record the shortest distance. The shortest distance between two points is the distance from the magenta circle to the center line of the scale line. The distance multiplied by a constant is the yaw angle.

[0105] The above description is only a further embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and concepts of the present invention within the scope disclosed by the present invention, which belong to the protection scope of the present invention.

Claims

1. A method for monitoring flight path guidance parameters in a PFD screen based on FPGA, characterized in that: include: Get the current PFD screen; Binarize the PFD screen at the current moment to obtain a binary image; The value of the pixel point of the first preset color in the binary image is the first preset value, the value of the pixel point of the second preset color is the second preset value, and the value of the pixel points of the remaining colors is 0; the first preset color is the color of the symbol of the aircraft in the PFD screen; The second preset color is the color of the target symbol in the PFD screen; Using a first preset window, starting from the upper left corner of the binary image, traversing the binary image from left to right and from top to bottom, obtaining the sum of the values ​​of all pixel points within the first preset mask range of the first preset window, and taking the center position corresponding to the maximum sum value greater than the first preset threshold as the center point coordinate of the aircraft symbol; obtaining the horizontal flight path according to all pixel points in the binary image whose values ​​are the first preset values ​​and the center point coordinate of the aircraft symbol; Using a second preset window, starting from the upper left corner of the binary image, traverse the binary image from left to right and from top to bottom, obtain the sum of the number of all pixel points whose values ​​are the second preset value within the second preset mask range of the second preset window, and take the center position corresponding to the maximum sum of the numbers greater than the second preset threshold as the center point coordinate of the target symbol; according to the center point coordinate of the target symbol and the center point coordinate of the aircraft symbol, obtain the vertical flight path; According to the roll angle of the aircraft and the coordinates of the origin of the aircraft in the binary image, the expression of the perpendicular bisector of the sky-ground line in the binary image is obtained; the shortest distance between the center point of the aircraft symbol and the perpendicular bisector of the sky-ground line in the binary image is obtained, and the flight guidance yaw angle is obtained according to the shortest distance; The horizontal flight path, vertical flight path and flight guidance yaw angle in the PFD screen are monitored according to the received horizontal flight path, vertical flight path and flight guidance yaw angle values.

2. The method for monitoring flight path guidance parameters in a PFD screen based on FPGA according to claim 1, characterized in that: The first preset color is magenta or pink, and the second preset color is green; The PFD screen at the current moment is binarized to obtain a binary image, including: Traverse the values ​​of all pixel points in the PFD screen at the current moment. When the value of the pixel point meets the requirements that the red component is greater than or equal to 0xEB, the green component is in the range of 0x23 to 0x41, and the blue component is greater than or equal to 0xEB, then the value of the pixel point is set to the first preset value; when the value of the pixel point meets the requirements that the red component is in the range of 0x5A to 0x6E, the green component is greater than or equal to 0XE6, and the blue component is less than or equal to 0x14, then the value of the pixel point is set to the second preset value, otherwise, the value of the pixel point is 0.

3. The method for monitoring flight path guidance parameters in a PFD screen based on FPGA according to claim 2, characterized in that: The first preset value is K, and the second preset value is 1; K is a weight multiple.

4. The method for monitoring flight path guidance parameters in a PFD screen based on FPGA according to claim 3, characterized in that: The first preset mask is a solid circle.

5. The method for monitoring flight path guidance parameters in a PFD screen based on FPGA according to claim 4, characterized in that: According to all pixel points in the binary image whose values ​​are the first preset values ​​and the coordinates of the center point of the aircraft symbol, a horizontal flight path is obtained, including: According to all the pixel points with the first preset value in the binary image and the coordinates of the center point of the local symbol, the least squares fitting principle is used to calculate the formula Get the local symbol slope b; Determine the horizontal flight path based on the own-ship symbol slope; Among them, x i is the difference between the x coordinate of the pixel point with the first preset value and the center point of the local symbol, y i is the difference between the y coordinate of the pixel point whose value is the first preset value and the center point of the local symbol, and n is the number of pixel points whose value is the first preset value. According to the slope of the own aircraft symbol, the FD horizontal angle is obtained by looking up the ROLL_ATAN_VAL_ROM module as the horizontal flight path.

6. The method for monitoring flight path guidance parameters in a PFD screen based on FPGA according to claim 3, characterized in that: The second preset mask is two symmetrical arc segments on the same circular ring.

7. The method for monitoring flight path guidance parameters in a PFD screen based on FPGA according to claim 6, characterized in that: According to the center point coordinates of the target symbol and the center point coordinates of the own aircraft symbol, the vertical flight path is obtained, including: Get the distance between the center point of the target symbol and the center point of the own aircraft symbol; Obtain the vertical angle value according to the distance and the preset distance-angle conversion coefficient; Determine the sign bit of the vertical angle value according to the positional relationship between the center point coordinates of the target symbol and the center point coordinates of the own aircraft symbol; Based on the sign bit and the vertical angle value, the vertical flight path is determined.

8. A flight path guidance parameter monitoring device in a PFD screen based on FPGA, characterized in that: Used to perform the method according to any one of claims 1 to 7.

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