1. A digitized frock aircraft coordinate system calibration method based on temperature compensation is characterized in that the digitized frock aircraft coordinate system is calibrated by the coordinates of ERS point group, the ERS point group comprises ERS basic point group and ERS enhancement point group, the ERS basic point group comprises 3 ERS points which are respectively ERS1, ERS2 and ERS3, the ERS enhancement point group comprises the number of ERS points which is not limited, the ERS point group envelops the digitized frock, comprising the following steps:

step 1, defining the design coordinates of ERS point group in CAD global coordinate system { C }

Step 2 is according toDesigning coordinates and setting ERS point groups on the digital equipment;

and 3, recording the coefficient of expansion with heat and contraction with cold of the digital tool: c;

and step 4, recording the ambient temperature when the aircraft coordinate system { P } is calibrated: WE;

step 5 defines the reference temperature at which { P } is calibrated as: RF;

step 6, recording the actual coordinates of ERS point group at WE temperature relative to the coordinate system { M } of the measuring equipment

Step 7 of determining the difference between RE and RF

Step 8, constructing a temperature compensation coefficient delta:

step 9, defining a tool coordinate system { T }: the origin of { T } is set at ERS1 point, and the X direction of { T } is set as vectorIn the direction of (1), the 0XY plane of { T } is a vectorSum vectorThe Z direction of the formed plane, { T } is defined as a vectorRotated to vector by right hand ruleThe pointing direction of the thumb;

step 10, constructing a fitting coordinate of ERS basic point group relative to { T } after temperature compensationComprises the following steps:

10-1 finding the vectorModulus of

10-2 finding the vectorModulus of

10-3 finding the vectorAnd vectorAngle Θ of (c):

10-4 construction of virtual Displacement

10-5 constructing fitted coordinates of ERS basic point group relative to { T } after temperature compensation

Step 11, at the RF temperature, constructing the pose of { T } relative to { P }Comprises the following steps:

11-1 construction of X-direction of { T } cosine in the direction of { P }:

the result of equation 10 is substituted into equation 11, and the cosine of { T } in the X direction in { P } is obtained:

11-2 construction of Z-direction of { T } cosine in the direction of { P }:

the result of equation 12 is substituted into equation 13, and the cosine of { T } in the Z direction in { P } direction is obtained:

11-3 construction of the Y-direction of { T } cosine in the direction of { P }:

the result of equation 14 is substituted into equation 15, and the cosine of { T } in the Y direction in { P } direction is obtained:

11-4 at RF temperature, build the pose of { T } relative to { P }

Step 12 at RF temperature, build the pose of { M } relative to { T }Comprises the following steps:

12-1 construction of ERS base point group, the normal vector of the plane formed by the ERS base point group is in the direction cosine of { M }:

the result of equation 17 is taken into equation 18, and the direction cosine of the normal vector of the plane constituted by the ERS base point group in { M } is obtained:

12-2 construct the compensated coordinates of ERS base point population at RF temperature versus { M }:

12-3 construction of compensated pose of { M } at RF temperature relative to { T }

Step 13 is to calculate the calibration coordinates of ERS point group relative to the plane coordinate system { P } at RF temperature

2. The method of claim 1, wherein the ERS point group is disposed on a high-rigidity structure in the digital tooling.

3. The method for calibrating the coordinate system of the digital tooling aircraft based on the temperature compensation as claimed in claim 1, wherein the ERS basic point group is a vectorSum vectorA parallelogram formed by adjacent edges is enveloped with a digital tool in a two-dimensional plane form, andhas a modulus of more thanThe modulus of (a).

4. The method for calibrating the aircraft coordinate system of the digital tooling based on the temperature compensation as claimed in claim 1, wherein the ERS enhancement point groups are arranged on the digital tooling at uniform intervals, and the ERS basic point groups and the ERS enhancement point groups envelop the digital tooling in a three-dimensional form.

5. The method for calibrating the coordinate system of the digital tooling airplane based on the temperature compensation is characterized in that the ERS points are geometric points obtained by spherical fitting, circular fitting, triangular prism fitting or comprehensive cylindrical and plane fitting.

Background

The digitalized assembly airplane coordinate system is a reference for digitalized assembly and inspection of airplanes, a measuring point group-ERS point group is arranged on the digitalized assembly, and the digitalized tooling calibrates the airplane coordinate system by using ERS point group coordinates. As a benchmark for the digital manufacturing and inspection of airplanes, the digital tooling airplane coordinate system is required to have long-term stability, wherein temperature change is an important factor influencing the long-term stability. For a new generation of airplane, the pose deviation of a digital tooling airplane coordinate system cannot exceed 0.2 mm. However, the digital tooling has the characteristics of expansion with heat and contraction with cold, taking a 10-meter-long digital tooling of an airplane as an example, the deviation of the temperature difference of 10 ℃ to the coordinate system of the airplane of the digital tooling exceeds 1.2mm, if the temperature compensation is not carried out when the coordinate system of the digital tooling airplane is calibrated, the calibrated airplane coordinate system does not have the temperature stability, and the airplane manufactured according to the coordinate system of the digital tooling airplane has serious quality problems. The technical scheme adopted at present is as follows: firstly, controlling the temperature of a workshop to enable the digital equipment to be in a relatively constant temperature environment; 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 point of the technical scheme is to control the deviation of the coordinate system of the digital industry airplane loader, 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 during calibration of a digital tooling aircraft coordinate system, the invention discloses a method for calibrating the digital tooling aircraft coordinate system based on temperature compensation.

The invention adopts the following technical scheme:

a digitalized tooling aircraft coordinate system calibration method based on temperature compensation is characterized in that the digitalized tooling aircraft coordinate system is calibrated by coordinates of ERS point groups, the ERS point groups comprise ERS basic point groups and ERS enhancement point groups, the ERS basic point groups comprise 3 ERS points which are respectively ERS1, ERS2 and ERS3, the ERS enhancement point groups comprise unlimited number of ERS points, the number of ERS enhancement point groups is determined by the size of the digitalized tooling, the size is small, the ERS enhancement point group is not required to be arranged, when the size is large, the ERS enhancement point group is required to be arranged, the ERS basic point group and the ERS enhancement point group are both composed of ERS points, the ERS points are geometric points obtained by spherical fitting, circular fitting, prism fitting or comprehensive fitting of a cylindrical surface and a plane, the ERS points are carriers for calibrating an airplane coordinate system by a digital tool, and the method for calibrating the airplane coordinate system by the digital tool based on temperature compensation comprises the following steps:

step 1, defining ERS point group in CAD holonomicDesign coordinates of the local coordinate System { C }

Step 2 is according toDesigning coordinates and setting ERS point groups on the digital equipment;

and 3, recording the coefficient of expansion with heat and contraction with cold of the digital tool: c;

and step 4, recording the ambient temperature when the aircraft coordinate system { P } is calibrated: WE;

step 5 defines the reference temperature at which { P } is calibrated as: RF;

step 6, recording the actual coordinates of ERS point group at WE temperature relative to the coordinate system { M } of the measuring equipment

Step 7 of determining the difference between RE and RF

Step 8, constructing a temperature compensation coefficient delta:

step 9, defining a tool coordinate system { T }: the origin of { T } is set at ERS1The X direction of the point, { T } is defined as a vectorIn the direction of (1), the 0XY plane of { T } is a vectorSum vectorThe Z direction of the formed plane, { T } is defined as a vectorRotated to vector by right hand ruleThe pointing direction of the thumb;

step 10, constructing a fitting coordinate of ERS basic point group relative to { T } after temperature compensationComprises the following steps:

10-1 finding the vectorModulus of

10-2 finding the vectorModulus of

10-3 finding the vectorAnd vectorAngle Θ of (c):

10-4 construction of virtual Displacement

10-5 construction of fitting coordinates of ERS basic point group relative to { T } after temperature compensation

Step 11, at the RF temperature, constructing the pose of { T } relative to { P }Comprises the following steps:

11-1 construction of X-direction of { T } cosine in the direction of { P }:

the result of equation 10 is substituted into equation 11, and the cosine of { T } in the X direction in { P } is obtained:

11-2 construction of Z-direction of { T } cosine in the direction of { P }:

the result of equation 12 is substituted into equation 13, and the cosine of { T } in the Z direction in { P } direction is obtained:

11-3 construction of the Y-direction of { T } cosine in the direction of { P }:

the result of equation 14 is substituted into equation 15, and the cosine of { T } in the Y direction in { P } direction is obtained:

11-4 at RF temperature, build the pose of { T } relative to { P }

Step 12 at RF temperature, build the pose of { M } relative to { T }Comprises the following steps:

12-1 construction of ERS base point group, the normal vector of the plane formed by the ERS base point group is in the direction cosine of { M }:

the result of equation 17 is taken into equation 18, and the direction cosine of the normal vector of the plane constituted by the ERS base point group in { M } is obtained:

12-2 construct the compensated coordinates of ERS base point population at RF temperature versus { M }:

12-3 construction of compensated pose of { M } at RF temperature relative to { T }

Step 13 is to calculate the calibration coordinates of ERS point group relative to the plane coordinate system { P } at RF temperature

ERS point groups are arranged on a high-rigidity structure in the digital tool.

Vector in ERS base point groupSum vectorA parallelogram formed by adjacent edges is enveloped with a digital tool in a two-dimensional plane form, andhas a modulus of more thanThe modulus of (a).

ERS enhancement point groups are arranged on the digital assembly at uniform intervals, and the ERS basic point groups and the ERS enhancement point groups envelop the digital assembly in a three-dimensional form.

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

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

(1) the calibration of the airplane coordinate system with the digital tool, low cost, high efficiency and high stability is realized. By applying the method disclosed by the application patent, a constant temperature workshop or a material with low thermal expansion and cold contraction is not needed when the digital chemical equipment is used for calibrating the airplane coordinate system.

(2) The accuracy of the calibration of the coordinate system of the digital industrial airplane is improved. Because absolute constant temperature and zero expansion and contraction materials do not exist, the existing aircraft coordinate system calibration method has certain errors. Based on the method disclosed by the application patent, when a coordinate system is calibrated, the coordinate deviation caused by temperature change is compensated, and the calibration accuracy 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 calibration based on temperature compensation.

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

Detailed Description

Fig. 1 is a schematic diagram of calibration of a coordinate system of a digital tooling airplane, the length of the digital tooling is about 6 meters, the height of the digital tooling is about 3.3 meters, the width of the digital tooling is about 2.6 meters, the material is Q235, the coefficient of expansion with heat and contraction with cold C is 0.012 mm/(m.DEG C), and the assembled object is an airplane side wall plate 4. Since the aircraft sidewall plate 4 is enveloped by the rectangular frame of the digital tooling 1, and the length of the rectangle is greater than the height, the ERS1 point in the ERS basic point group consisting of the ERS points 2 is set at the lower left of the rectangular frame, the ERS2 point in the ERS basic point group is set at the lower right of the rectangular frame, and the ERS3 point in the ERS basic point group is arranged at the upper left of the rectangular frame. Because the size of the digital tool is larger, an ERS enhancement point group is also arranged, the distance between ERS points in the ERS enhancement point group is controlled to be about 1.5 meters, and the adopted measuring equipment is calibrated to be a non-contact laser tracker 3.

As shown in fig. 1, the carrier serving as the ERS spot is a cylinder, e.g. finger-sized, with a precise inner bore and a precise outer end surface. And intersecting the hole axis and the end plane by fitting the hole axis of the accurate inner hole and fitting the end plane of the accurate outer end surface to obtain an intersection point, and offsetting the intersection point along the hole axis in a direction away from the cylinder by a certain displacement amount, wherein the offset intersection point is an ERS point. Specifically for the Leica960 laser tracker as shown, this displacement is 12.7 mm.

Taking the digital tool shown in fig. 1 as an example, a method for calibrating an aircraft coordinate system of the digital tool based on temperature compensation is described in detail, and the method comprises the following specific steps:

step 1, defining the design coordinates of ERS point group in CAD global coordinate system { C }

Step 2 is according toDesigning coordinates and setting ERS point groups on the digital equipment;

and 3, recording the coefficient of expansion with heat and contraction with cold of the digital tool: c;

and step 4, recording the ambient temperature when the aircraft coordinate system { P } is calibrated: WE;

step 5 defines the reference temperature at which { P } is calibrated as: RF;

step 6, recording the actual coordinates of ERS point group at WE temperature relative to the coordinate system { M } of the measuring equipment

Step 7 of determining the difference between RE and RF

Step 8, constructing a temperature compensation coefficient delta:

step 9, defining a tool coordinate system { T }: the origin of { T } is set at ERS1 point, and the X direction of { T } is set as vectorIn the direction of (1), the 0XY plane of { T } is a vectorSum vectorThe Z direction of the formed plane, { T } is defined as a vectorRotated to vector by right hand ruleThe pointing direction of the thumb;

step 10, constructing a fitting coordinate of ERS basic point group relative to { T } after temperature compensationComprises the following steps:

10-1 finding the vectorModulus of

10-2 finding the vectorModulus of

10-3 finding the vectorAnd vectorAngle Θ of (c):

10-4 construction of virtual Displacement

10-5 construction of fitting coordinates of ERS basic point group relative to { T } after temperature compensation

Step 11, at the RF temperature, constructing the pose of { T } relative to { P }Comprises the following steps:

11-1 construction of X-direction of { T } cosine in the direction of { P }:

the result of equation 10 is substituted into equation 11, and the cosine of { T } in the X direction in { P } is obtained:

11-2 construction of Z-direction of { T } cosine in the direction of { P }:

the result of equation 12 is substituted into equation 13, and the cosine of { T } in the Z direction in { P } direction is obtained:

11-3 construction of the Y-direction of { T } cosine in the direction of { P }:

the result of equation 14 is substituted into equation 15, and the cosine of { T } in the Y direction in { P } direction is obtained:

11-4 at RF temperature, build the pose of { T } relative to { P }

Step 12 at RF temperature, build the pose of { M } relative to { T }Comprises the following steps:

12-1 construction of ERS base point group, the normal vector of the plane formed by the ERS base point group is in the direction cosine of { M }:

the result of equation 17 is taken into equation 18, and the direction cosine of the normal vector of the plane constituted by the ERS base point group in { M } is obtained:

12-2 construct the compensated coordinates of ERS base point population at RF temperature versus { M }:

12-3 construction of compensated pose of { M } at RF temperature relative to { T }

Step 13 is to calculate the calibration coordinates of ERS point group relative to the plane coordinate system { P } at RF temperature

ERS point groups are arranged on a high-rigidity structure in the digital tool.

Vector in ERS base point groupSum vectorA parallelogram formed by adjacent edges is enveloped with a digital tool in a two-dimensional plane form, andhas a modulus of more thanThe modulus of (a).

ERS enhancement point groups are arranged on the digital assembly at uniform intervals, and the ERS basic point groups and the ERS enhancement point groups envelop the digital assembly in a three-dimensional form.

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