Method and device for monitoring pitching parameters in PFD picture based on FPGA

Abstract

The invention provides a method and a device for monitoring pitching parameters in a PFD (Performance Frequency Division) picture based on an FPGA (Field Programmable Gate Array), which are characterized in that a specially-made pitching recognition pattern template is obtained on the basis of an actual display picture, and the template can effectively resist the problems of fuzzy pattern boundary and slight offset of a pattern display position after binarization, which are introduced during rendering and anti-aliasing processing during GPU (Graphics Processing Unit) drawing; and carrying out sliding matching on the pitching template in the pitching image which is reversely rotated according to the rolling value after binarization, obtaining a reference value according to the minimum matching error, and calculating the current pitching value according to the distance from the reference value to the central point. The method is realized based on the minimum template matching error, the pitching value can be accurately identified, the display reliability is improved, the average fault interval time is prolonged, and the flight safety is ensured.

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, and metric Mach number.

[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 directly output to 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] Pitch is a dynamic parameter that moves in tandem with roll, and its displayed value plays an important role in guiding the pilot's current flight attitude. Summary of the invention

[0005] The present invention provides a method and device for monitoring pitch parameters in a PFD screen based on FPGA, which can monitor the pitch parameters in the PFD screen.

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

[0007] Get the current PFD screen;

[0008] Binarization is performed on the pitch display window of the PFD screen at the current moment to obtain a binary image;

[0009] Using the rolling value, the binary image is reversely rotated around the center point to obtain the rotated image;

[0010] Extract two rectangular target areas from the rotated image, where the rectangular target areas are areas including the pitch scale values;

[0011] Using a preset character image template to perform sliding matching on two rectangular target areas, determining a comparison area corresponding to a minimum target matching error and a value in the preset character image template in the two rectangular target areas;

[0012] Determine the pitch value in the PFD screen according to the value in the preset character image template and the longitudinal distance between the comparison area and the center point;

[0013] Based on the received pitch value, the pitch value in the PFD screen is monitored.

[0014] Optionally, before binarizing the pitch display window of the PFD screen at the current moment, the method further includes:

[0015] Taking the center point of the current PFD screen as the core, capture the pitch display window image of a preset size.

[0016] Optionally, before binarizing the pitch display window of the PFD screen at the current moment, the method further includes:

[0017] Get the PFD screen under multiple roll values;

[0018] Capture character image templates from the PFD screen under multiple roll values;

[0019] Binarizing the character image template to obtain a binary character image template;

[0020] Performing an inverse rolling value rotation on the binary character image template to obtain a rotated character image template;

[0021] The pixel distribution statistics fusion processing is performed on the rotated character image templates under multiple rolling values ​​to obtain a preset character image template.

[0022] Optionally, roll values ​​include: 60°, 45°, 15°, 0°, -15°, -45°, and -60°.

[0023] Optionally, there are multiple character image templates, each of which contains a numerical value;

[0024] The value in the character image template is 2, 3, 4, 5, or 7.

[0025] Optionally, the character image template is binarized using the same threshold as that used for binarizing the pitch display window of the PFD screen at the current moment.

[0026] Optionally, a preset character image template is used to perform sliding matching on two rectangular target areas, including:

[0027] In the two rectangular target areas, from left to right and from top to bottom, with one pixel as the sliding unit, a comparison area with the same size as the preset character image template is obtained from the two rectangular target areas, and the difference between the sum of the pixel values ​​​​between the comparison area and the preset character image template is obtained as the target matching error.

[0028] A second aspect of the present invention provides a pitch 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 pitch parameters in a PFD screen based on FPGA. Based on the actual display screen, a special pitch recognition graphic template is obtained. This template can effectively resist the problem of graphic boundary blurring and slight offset of the graphic display position after binarization due to rendering and anti-aliasing processing during GPU drawing. The pitch template is slidably matched in the pitch image that is reversely rotated according to the roll value after binarization, and a reference value is obtained according to the minimum matching error. The current pitch value is calculated according to the distance from the reference value to the center point. The present invention is based on the minimum template matching error, can accurately identify the pitch value, improve display reliability, increase the mean time between failures, and ensure flight safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of pitch display;

[0031] Figure 2 Template diagram;

[0032] Figure 3 Target area;

[0033] Figure 4 Pitch recognition flow chart

[0034] Figure 5 Schematic diagram of sliding matching. DETAILED DESCRIPTION

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] like Figure 1-5 As shown, in the actual operating environment, the present invention collects PFD images under different conditions, comprehensively collects the data, selects a suitable pitch display window binarization threshold, and iteratively obtains a pitch value recognition template based on this.

[0040] When the FPGA is initialized, the pitch template is stored in the on-chip ROM (5 templates with the letters 2, 3, 4, 5, and 7). Before pitch recognition, the pitch display window of the PFD screen needs to be binarized. The binarization method used should be the same as that used when making the pitch template. According to the calculated roll value, reverse rotation is performed around the center point to obtain the following: Figure 3 The target area shown (such as Figure 3 The left and right target areas are stored in two RAMs respectively; the template data stored in the five ROMs are then matched with the target area data stored in the RAMs; during the matching process, the minimum target matching error is recorded, and then the template with the minimum matching error among the five templates is selected, which is the number to be calculated, and then the current pitch value is calculated based on the distance from this number to the center point. Figure 3 For example, the distance from "40" to the center point is 82 pixels, so the pitch value is 40-82 / 9.1≈31. Here 9.1 is the conversion constant between pixel value and pitch scale.

[0041] A certain embodiment of the present invention includes the following contents:

[0042] (1) Pitch recognition process

[0043] The flow chart is shown in the figure below. First, the video is binarized, and then a 512x512 image is intercepted and stored in RAM with the center point as the core. The image is rotated by the inverse roll angle to obtain a positive image, and then the left and right target areas are intercepted and stored in two RAMs respectively. The templates 2, 3, 4, 5, and 7 are respectively slide matched in the target area to obtain the minimum matching error, and the coordinates at this time are recorded, and then the value with the smaller error in the left and right target areas is taken, and then the current pitch value is obtained by the distance from this number to the center point.

[0044] Exemplarily, the template matching process is as follows Figure 5 As shown, the size of the template ROM is 21x12 and the RAM of a single target area is 500x32.

[0045] Exemplarily, the pitch value identification module performs the following:

[0046] 1) The pitch display window image input to the pitch value recognition module has been binarized, and the binarization method is consistent with that used when making the pitch template;

[0047] 2) The image frame with the center point as the core is rotated against the roll angle, and the target area with pitch scale value is stored in RAM;

[0048] 3) The pitch value recognition template ROM is initialized when the FPGA is powered on, and what is stored is the pitch value recognition template;

[0049] 4) During sliding matching, the templates 2, 3, 4, 5, and 7 are slid in the two target areas respectively. Every time one pixel is slid, the matching error between the airspeed image and the airspeed template is calculated. The matching error is the number of mismatched character pixels in the binarized image and the template.

[0050] 5) Each time the sliding match obtains the matching error of each digital template, the position of the minimum error is recorded at the same time, and then the error of 2, 3, 4, 5, 7 is determined to be the smallest, and the corresponding value is taken, and the difference between the coordinates at this time and the center is calculated, and finally the pitch value is obtained, that is: pitch value = template value with the smallest error - (corresponding to the vertical coordinate of the minimum matching point - the vertical coordinate of the center point) / 9.1 (ratio of pixel point to pitch value). Here, if the sky-sky line is below the center point, the pitch value is positive at this time. If the sky-sky line is above the center point, the pitch value is negative at this time.

[0051] (2) Preparation of pitch recognition architecture image matching template:

[0052] The template is made in the following way: collect 2, 3, 4, 5, 7 character images at 60°, 45°, 15°, 0°, -15°, -45°, -60° display conditions, determine the binarization threshold to binarize the character image, and use the binarization result after reverse rotation as the material for making the template. Due to rendering and rotation accuracy issues, many error points will appear after rotating the same number at different angles. Analyze which pixels are on the template and form a template based on pixel distribution statistics. The final template is as follows Figure 2 shown.

[0053] The present invention proposes a statistical template production method. Due to rendering and rotation accuracy issues, the numerical points after rotation will have deviations, and it is necessary to reversely rotate at multiple angles (covering the monitored angle range) to count the distribution of corresponding numbers, thereby producing a template of the corresponding numbers.

[0054] 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 pitch parameters in a PFD screen based on FPGA, characterized in that: include: Get the current PFD screen; Binarization is performed on the pitch display window of the PFD screen at the current moment to obtain a binary image; Using the rolling value, the binary image is reversely rotated around the center point to obtain the rotated image; Extract two rectangular target areas from the rotated image, where the rectangular target areas are areas including the pitch scale values; Using a preset character image template to perform sliding matching on two rectangular target areas, determining a comparison area corresponding to a minimum target matching error and a value in the preset character image template in the two rectangular target areas; Determine the pitch value in the PFD screen according to the value in the preset character image template and the longitudinal distance between the comparison area and the center point; Based on the received pitch value, the pitch value in the PFD screen is monitored.

2. The method for monitoring pitch parameters in a PFD screen based on FPGA according to claim 1, characterized in that: Before binarizing the pitch display window of the PFD screen at the current moment, the method further includes: Taking the center point of the current PFD screen as the core, capture the pitch display window image of a preset size.

3. The method for monitoring pitch parameters in a PFD screen based on FPGA according to claim 1, characterized in that: Before binarizing the pitch display window of the PFD screen at the current moment, the method further includes: Get the PFD screen under multiple roll values; Capture character image templates from the PFD screen under multiple roll values; Binarizing the character image template to obtain a binary character image template; Performing an inverse rolling value rotation on the binary character image template to obtain a rotated character image template; The pixel distribution statistics fusion processing is performed on the rotated character image templates under multiple rolling values ​​to obtain a preset character image template.

4. The method for monitoring pitch parameters in a PFD screen based on FPGA according to claim 3, characterized in that: Roll values ​​include: 60°, 45°, 15°, 0°, -15°, -45°, and -60°.

5. The method for monitoring pitch parameters in a PFD screen based on FPGA according to claim 3, characterized in that: There are multiple character image templates, and each character image template contains a numerical value; The value in the character image template is 2, 3, 4, 5, or 7.

6. The method for monitoring pitch parameters in a PFD screen based on FPGA according to claim 3, characterized in that: The character image template is binarized using the same threshold as that used for binarizing the pitch display window of the PFD screen at the current moment.

7. The method for monitoring pitch parameters in a PFD screen based on FPGA according to claim 1, characterized in that: Use the preset character image template to perform sliding matching on two rectangular target areas, including: In the two rectangular target areas, from left to right and from top to bottom, with one pixel as the sliding unit, a comparison area with the same size as the preset character image template is obtained from the two rectangular target areas, and the difference between the sum of the pixel values ​​​​between the comparison area and the preset character image template is obtained as the target matching error.

8. A pitch 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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