CN107576283B

CN107576283B - Method for indirectly determining aircraft water splash angle by means of optical measurement parameters

Info

Publication number: CN107576283B
Application number: CN201710804703.3A
Authority: CN
Inventors: 高扬; 杜毅洁; 潘鹏飞; 申晓霞; 李飞行
Original assignee: Chinese Flight Test Establishment
Current assignee: Chinese Flight Test Establishment
Priority date: 2017-09-08
Filing date: 2017-09-08
Publication date: 2021-08-03
Anticipated expiration: 2037-09-08
Also published as: CN107576283A

Abstract

The invention belongs to a test technology, and particularly relates to a method for indirectly determining a water splashing angle of an airplane by means of optical measurement parameters. The invention provides a coordinate transformation-based splash track angle optical determination method, which specifically comprises the following steps of 1: establishing a geometric relation between the original coordinate system and the converted new coordinate system; step 2: arranging cameras in the oblique front and on two sides of the runway according to requirements; and step 3: carrying out a water splashing test, and calculating a front viewing angle and a side viewing angle of a water splashing track under a new coordinate system by means of an optical camera; and 4, step 4: and (4) indirectly calculating to obtain a positive visual angle and a side visual angle of the splash track under the original coordinate by means of the coordinate system incidence relation established in the step (1). The invention provides a new testing method for solving the problem of obtaining a water splashing track in a water splashing test of an original complete machine.

Description

Method for indirectly determining aircraft water splash angle by means of optical measurement parameters

Technical Field

The method is applied to the whole machine water splashing test, the water splashing angle of the airplane is indirectly determined by means of the optical measurement result, and a basis is provided for judging the test result.

Background

The whole machine splash test is a test subject specified by civil aircraft research and development, qualification approval and military aircraft identification and setting. After the test is finished, characteristic splash angles of the whole machine are required to be provided, wherein the characteristic splash angles comprise a front view angle and a side view angle of a splash track. The water splashing angle obtained in the test can be compared with a design calculation value, and the checking of the prediction method is realized.

The determination of the splash angle is usually carried out by optical measurement methods. The most direct mode for acquiring the positive visual angle is to erect a camera in the dead ahead of the aircraft sliding for shooting, the shooting effect is difficult to guarantee due to the influence of the distance, and hidden dangers can be brought to the flight safety by shooting in the dead ahead. If the angle is acquired by means of aerial photography, only an approximate normal viewing angle can be obtained on one hand, and on the other hand, flight safety is affected.

Aiming at the problems of determining the whole machine water splashing test angle, an indirect determination method by means of optical measurement parameters is provided, firstly, a measurement coordinate system is transformed, the water splashing angle in the transformed coordinate system is determined, and then the water splashing angle in the coordinate system before transformation is indirectly obtained by combining a transformation relation formula between the coordinate systems, so that the problems caused by the traditional method are effectively avoided.

The invention relates to a method for indirectly determining a splash angle, measuring coordinate transformation, arrangement of optical measuring equipment and the like.

Disclosure of Invention

The purpose of this patent is: an optical measurement method is designed for indirectly determining the water splashing angle of an airplane in a complete machine water splashing test.

The technical scheme of this patent is:

the method for indirectly determining the splash angle of the airplane by means of optical measurement parameters comprises five parts, namely definition of an original coordinate system, parameter transformation relation of a rotating coordinate system, design of a camera position layout scheme, determination of the splash angle of the rotating coordinate system and determination of the splash angle of the original coordinate system.

Step 1: defining the course of the airplane as an X axis, the reverse direction of gravity as a Y axis, defining a Z axis according to a left-hand rule, recording a water splashing trajectory line in a three-dimensional rectangular coordinate system as OP, a water splashing side view angle theta as an included angle between the projection of the OP on a YOZ plane and the Z axis, and a water splashing forward view angle gamma as an included angle between the projection of the OP on an XOZ plane and the X axis;

step 2: and rotating the original coordinate system counterclockwise by an angle epsilon around a Y axis in the vertical direction, and establishing an incidence relation between geometrical angles between the coordinate systems before and after rotation, wherein X and Z are coordinates before transformation, X 'and Z' are coordinates of a new coordinate system after rotation, and epsilon is a rotation angle.

The relation is satisfied between the coordinates before and after rotation:

cosε·x′＝x+z′·sinε (1)

then there are: x '. cos ε -z'. sin ε (2)

The method comprises the following steps: z ═ x '. sin epsilon + z'. cos epsilon (3)

And the coordinate of the vertical direction before and after rotation is unchanged, namely:

y＝y′ (4)

the relationship between the coordinate systems before and after rotation can be expressed as:

and step 3: high-speed cameras are arranged on two sides of a runway and used for shooting a splash track, the camera C3 is arranged in the direction that the water inlet point of the airplane forms an epsilon angle with the heading direction, and the cameras A1 and B2 are respectively arranged on two sides of a water pool in the direction perpendicular to the direction.

And 4, step 4: the front view gamma 'and the side view angle theta' of the splash track in the coordinate system after rotation can be obtained by utilizing the cameras A1, B2 and C3;

and 5: obtaining a water splashing track front view angle and a side view angle in a coordinate system before rotation by adopting the following expressions:

and the depression angle of the water splashing track in the coordinate system before rotation:

the advantage of this patent is:

the indirect determination method by means of the optical measurement parameters is provided, firstly, a measurement coordinate system is transformed, the splashing angle in the transformed coordinate system is determined, and then the splashing angle in the coordinate system before transformation is indirectly obtained by combining a transformation relational expression between the coordinate systems, so that the problems of test safety and calculation result accuracy brought by the traditional method are effectively solved.

Drawings

Fig. 1 is a three-dimensional geometric schematic diagram of a splash trajectory, and a definition diagram of a front view, a side view and a top view.

FIG. 2 is a schematic diagram of the geometrical relationship before and after the rotation of the coordinate system.

Fig. 3 is a schematic diagram of the position of an optical camera used in a splash test to indirectly determine the splash angle.

Detailed Description

1) Determination of the rotation angle epsilon of a coordinate system

The rotation angle epsilon is selected as the actual situation, in order to ensure the image definition and the image quality, the front camera C3 should not be too far away, the farthest distance should not exceed 500m, and the arrangement of the cameras should not affect the normal operation of the test, for example, the distances between the cameras A1 and B2 and the center line of the runway should not be less than 50m, as shown in FIG. 1. In order to ensure the imaging quality of the three cameras simultaneously, the maximum value of the rotation angle epsilon is preferably 3-5 degrees, as shown in fig. 2.

2) Determination of intersection point O between connecting line of cameras A1 and B2 and perpendicular line of camera C3

In order to ensure that a fully developed splash trajectory can be obtained, the determination of the intersection point O is selected as much as possible at the center of the splash tank close to the water outlet side of the aircraft and on the center line of the splash tank, as shown in fig. 3.

Claims

1. The method for indirectly determining the splash angle of the airplane by means of optical measurement parameters is characterized by comprising five parts, namely definition of an original coordinate system, parameter transformation relation of a rotating coordinate system, design of a camera position layout scheme, determination of the splash angle of the rotating coordinate system and determination of the splash angle of the original coordinate system; defining the original coordinate system as X axis, Y axis in the opposite direction of gravity, defining Z axis according to left-hand rule, recording the water splashing trajectory line in the three-dimensional rectangular coordinate system as OP, the side view angle theta of water splashing as the included angle between the projection of OP on the YOZ plane and the Z axis, and the forward view angle gamma of water splashing as the included angle between the projection of OP on the XOZ plane and the X axis; the parameter transformation relation of the rotating coordinate system is specifically that the original coordinate system rotates counterclockwise by an angle epsilon around a Y axis in the vertical direction, and an incidence relation between geometrical angles between the coordinate systems before and after rotation is established, wherein X and Z are coordinates before transformation, X 'and Z' are coordinates of a new coordinate system after rotation, epsilon is a rotation angle, and the relation between the coordinate systems before and after rotation can be expressed as:

the design of the position layout scheme of the cameras is that high-speed cameras are arranged on two sides of a runway and used for shooting a splash track, a camera 3 is arranged in the direction that the water entry point of an airplane forms an epsilon angle with the course, and cameras 1 and 2 are respectively arranged on two sides of a pool in the direction vertical to the direction;

the splash angle of the rotating coordinate system is determined specifically, a splash track front view gamma 'and a side view angle theta' in the rotating coordinate system can be obtained by utilizing the cameras 1, 2 and 3; the determination of the splashing angle of the original coordinate system specifically comprises the following steps of obtaining a splashing track positive visual angle, a side visual angle and a depression angle in the coordinate system before rotation by adopting the following expressions: