1. A digital industry dress aircraft coordinate system recovery method based on temperature compensation, characterized by that the aircraft coordinate system of the digitized frock is recovered by the coordinate of ERS point group, ERS point group is made up of 3 ERS points and more than, ERS point group envelops the digitized frock, comprising the following steps:

step 1, acquiring a calibration temperature of a coordinate system { P } of the digital industrial airplane: RF;

step 2, obtaining the mark of ERS point group relative to { P } at RF temperatureFixed coordinate

Step 3, recording the environmental temperature when the { P } is recovered: RE;

and 4, recording the coefficient of expansion with heat and contraction with cold of the digital tool: c;

step 5, recording the actual coordinates of the ERS point group at the RE temperature relative to the coordinate system { M } of the measuring equipment

Step 6, the difference between RE and RF is obtained

Step 7, constructing a temperature compensation coefficient delta:

step 8, constructing a fitting coordinate of the ERS point group relative to { M } after temperature compensation

Step 9, at RF temperature, constructing a function min (X Y Z a beta Γ) containing six unknowns, solving the function to obtain a solution of the unknowns at minimum:

solving to obtain:

step 10 at RF temperature, constructing the pose of { M } relative to { P }

Step 11 is to determine the compensated coordinates of ERS point group with respect to { P }

Step 12, compensating coordinates of ERS point group based on digital industry airplane coordinate system { P } after temperature compensationAnd (6) recovering.

2. The method for recovering the coordinate system of the digital industry dress aircraft based on the temperature compensation as claimed in claim 1, wherein the method is characterized in thatThe obtaining of the ERS point number comprises one-time measurement obtaining and multiple measurement obtaining, and when the ERS point number is obtained by multiple measurements, the ERS point number obtained by each measurement is not less than 3.

3. The method for recovering the coordinate system of the digital industry assembly airplane based on the temperature compensation as claimed in claim 1, wherein the ERS points are geometric points obtained by spherical fitting, circular fitting, triangular prism fitting or comprehensive fitting of a cylindrical surface and a plane.

4. The method for establishing the coordinate system of the digital tooling aircraft based on the temperature compensation is characterized in that the measuring equipment is coordinate measuring equipment and comprises contact coordinate measuring equipment and non-contact coordinate measuring equipment.

Background

The digital airplane-assembling coordinate system is a benchmark for digital assembly and inspection of airplanes and is required to have stability. Before the digital tool is delivered for use, the digital tool is provided with a measuring point group (ERS point group), and the digital tool calibrates an airplane coordinate system by using ERS point group coordinates. When the digital tool is used and regularly checked, the coordinate system of the digital tool airplane needs to be restored again according to the calibrated ERS point group coordinates.

Most aircraft assembly workshops are not constant temperature workshops, the digital chemical assembly is expanded with heat and contracted with cold due to the change of the environmental temperature, the ERS point deviates in position, and the digital chemical assembly aircraft coordinate system recovered again and the calibrated aircraft coordinate system have pose difference, so that the aircraft assembly reference deviates. Taking the assembly of a new generation of large-scale airplane as an example, the length of the digital tool is 30 meters, the annual average environmental temperature difference exceeds 10 ℃, and the deviation of the digital tool airplane coordinate system during recovery cannot exceed 0.2 mm. In fact, the deviation of the 10 ℃ temperature difference to the 10-meter-long digital tooling airplane coordinate system exceeds 1.2mm, and if the temperature compensation is not performed during the recovery of the digital tooling airplane coordinate system, the manufactured airplane has serious quality problems.

The currently adopted method for maintaining the stability of the coordinate system of the digital industry airplane loader comprises the following steps: firstly, controlling the temperature of a workshop to enable a digital chemical device to be arranged in a constant-temperature workshop; secondly, the digital tool is manufactured by adopting a material with smaller coefficient of expansion with heat and contraction with cold, for example, invar steel is adopted. The starting points of the technical scheme are all deformation of the control digital tool, but in the actual operation process, the technical scheme has the problems of high cost, low operability and low popularization.

Disclosure of Invention

In order to solve the problem of poor temperature stability when the coordinate system of the digital industry dress aircraft is restored again, the invention provides a method for restoring the coordinate system of the digital industry dress aircraft based on temperature compensation.

The invention adopts the following technical scheme:

a digital industry dress aircraft coordinate system recovery method based on temperature compensation, characterized by that the aircraft coordinate system of the digitized frock is recovered by the coordinate of ERS point group, ERS point group is made up of 3 ERS points and more than, ERS point group envelops the digitized frock, comprising the following steps:

step 1, acquiring a calibration temperature of a coordinate system { P } of the digital industrial airplane: RF;

step 2, acquiring calibration coordinates of ERS point group at RF temperature relative to { P }

Step 3, recording the environmental temperature when the { P } is recovered: RE;

and 4, recording the coefficient of expansion with heat and contraction with cold of the digital tool: c;

step 5, recording the actual coordinates of the ERS point group at the RE temperature relative to the coordinate system { M } of the measuring equipment

Step 6, the difference between RE and RF is obtained

Step 7, constructing a temperature compensation coefficient delta:

step 8, constructing a fitting coordinate of the ERS point group relative to { M } after temperature compensation

Step 9, at RF temperature, constructing a function min (X Y Z a beta Γ) containing six unknowns, solving the function to obtain a solution of the unknowns at minimum:

wherein c represents cos, s represents sin formula 6;

solving to obtain:

step 10 at RF temperature, constructing the pose of { M } relative to { P }

Step 11 is to determine the compensated coordinates of ERS point group with respect to { P }

Step 12, compensating coordinates of ERS point group based on digital industry airplane coordinate system { P } after temperature compensationAnd (6) recovering.

The obtaining of the ERS point number comprises one-time measurement obtaining and multiple measurement obtaining, and when the ERS point number is obtained by multiple measurements, the ERS point number obtained by each measurement is not less than 3.

ERS points are geometric points obtained by spherical fitting, circular fitting, triangular prism fitting or comprehensive cylindrical and plane fitting.

The measuring device is a coordinate measuring device and comprises a contact coordinate measuring device and a non-contact coordinate measuring device.

Compared with the prior art, the invention has the following advantages and obvious benefits:

(1) the problem of stability when the digital industry dress aircraft coordinate system resumes again under the temperature variation is solved. On the premise of no need of a constant-temperature workshop and a low-expansion-and-contraction-material, the stability of the ERS point group coordinates of the digital tool is realized through a compensation method, and the ERS point group coordinate system has remarkable economic benefit.

(2) The accuracy of recovering the digital chemical industry dress aircraft coordinate system again under the temperature variation is improved. Because the absolute constant temperature and the material with the coefficient of expansion with heat and contraction with cold being zero do not exist, certain errors always exist when the coordinate system of the existing digital tooling airplane is restored again. When the digital tooling airplane coordinate system is restored again according to the method, the calibrated digital tooling airplane coordinate system is compensated by constructing the temperature compensation coefficient, so that the accuracy of restoring the digital tooling airplane coordinate system again is improved.

The present application is described in further detail below with reference to the accompanying drawings of embodiments:

drawings

Fig. 1 is a schematic diagram of a digital tooling aircraft coordinate system recovery based on temperature compensation.

The numbering in the figures illustrates: 1 digital tool, 2ERS points, 3 laser trackers, 4 airplane lower wall plates and 5 tool branched chains

Detailed Description

Fig. 1 is a schematic diagram of the recovery of the coordinate system of the digital tooling airplane based on temperature compensation, wherein the digital tooling is composed of four tooling branched chains 5, the total length is about 4.5 meters, the height is about 2 meters, and the width is about 3 meters. The 9 ERS points 2 are arranged on a chassis of the digital tool and envelop the digital tool 1, the chassis is made of a steel structure, the coefficient C of thermal expansion and cold contraction is 0.013mm/(m DEG C), the assembled object is an airplane lower wall plate 4, and the measuring equipment adopts a non-contact laser tracker 3.

The carrier of the ERS spot 2 shown in fig. 1 is a cylinder, e.g. finger-sized, with a precise inner bore and a precise outer end surface. And through fitting the hole axis of the accurate inner hole and fitting the end plane of the accurate outer end face, offsetting the intersection point of the hole axis and the end plane by a certain displacement amount along the direction far away from the cylinder, wherein the offset intersection point is an ERS point 2. The laser tracker used in fig. 1 was of the Leica960 type, and the offset was 12.7 mm.

Taking the digital tool shown in fig. 1 as an example, a detailed description is given of a digital aircraft coordinate system recovery method based on temperature compensation, and the method comprises the following specific steps:

step 1, acquiring a calibration temperature of a coordinate system { P } of the digital industrial airplane: RF;

step 2, acquiring calibration coordinates of ERS point group at RF temperature relative to { P }

Step 3, recording the environmental temperature when the { P } is recovered: RE;

and 4, recording the coefficient of expansion with heat and contraction with cold of the digital tool: c;

step 5, recording the actual coordinates of the ERS point group at the RE temperature relative to the coordinate system { M } of the measuring equipment

Step 6, the difference between RE and RF is obtained

Step 7, constructing a temperature compensation coefficient delta:

step 8, constructing a fitting coordinate of the ERS point group relative to { M } after temperature compensation

Step 9, at RF temperature, constructing a function min (X Y Z a beta Γ) containing six unknowns, solving the function to obtain a solution of the unknowns at minimum:

wherein c represents cos, s represents sin formula 6;

solving to obtain:

step 10 at RF temperature, constructing the pose of { M } relative to { P }

Step 11 is to determine the compensated coordinates of ERS point group with respect to { P }

Step 12, compensating coordinates of ERS point group based on digital industry airplane coordinate system { P } after temperature compensationAnd (6) recovering.

The method for recovering the coordinate system of the digital airplane loader based on temperature compensation is characterized in thatThe obtaining of the ERS point number comprises one-time measurement obtaining and multiple measurement obtaining, and when the ERS point number is obtained by multiple measurements, the ERS point number obtained by each measurement is not less than 3.

ERS points are geometric points obtained by spherical fitting, circular fitting, triangular prism fitting or comprehensive cylindrical and plane fitting.

The measuring device is a coordinate measuring device and comprises a contact coordinate measuring device and a non-contact coordinate measuring device.