WO2019167012A1

WO2019167012A1 - System for measuring gap and flush

Info

Publication number: WO2019167012A1
Application number: PCT/IB2019/051662
Authority: WO
Inventors: Nicola Paone; Paolo CASTELLINI; Paolo CHIARIOTTI; Elisa MINNETTI
Original assignee: Università Politecnica delle Marche
Priority date: 2018-03-02
Filing date: 2019-03-01
Publication date: 2019-09-06
Also published as: IT201800003247A1

Abstract

The present invention relates to a portable measuring system aimed at measuring "gap and/or flush" between adjacent and not directly in-contact portions.

Description

SYSTEM FOR MEASURING GAP AND FLUSH

DESCRIPTION The present invention relates to a portable measuring system aimed at measuring“gap” and“flush” between adjacent and not directly in-contact portions.

Background

Under the term“gap” the width of the interstice between two portions of an object and/or between two surfaces, measured in the plane tangent to the surfaces under examination, is meant (Figure 1).

Under the term “flush” the alignment between two surfaces, meant as the distance between the surfaces measured in the direction orthogonal to the plane tangent to the surfaces under examination, is meant.

Figure 1 schematizes the meaning of gap and flush.

Typical examples are the measurement of gap and flush of a car door with respect to the body or an oven door with respect to the oven structure or of the optical groups of a vehicle with respect to the body.

The measurement of gap and flush between adjacent portions is currently used to check both aesthetical and functional specifications. In a car, for example, the measurement of gap and flush between points of the door with respect to the body allows to evaluate both pleasantness from the aesthetical point of view and assembly conformity from the functional point of view. The measurement result can be used in case to correct the door positioning should the measured values not meet specifications.

The known art shows several portable laser triangulation devices for measuring gap and flush.

US5999265 describes a method for the measurement of gap and flush between adjacent, not directly in-contact portions, through a triangulation system with parallel light planes.

AT506110 A1 describes a method, based upon the identification of the laying of an optical triangulation system with respect to the solid body thereof one wishes to detect the shape, aimed at strengthening the measurement. US8274662 describes a laser triangu!ation measurement instrument the new features thereof relate to i) the use of masks for generating several light planes having arbitrary shape starting from one single emitting source, ii) in the presence of a guiding element for centering the light plane/s through a hole, iii) in the presence of a device useful to position the instrument depending upon the features to be measured.

US20170003393 describes a triangulation system for measuring gap between the ending tip of the blade of a turbine and the case of the turbine itself.

However, the known devices up to now have important limits.

For example, the known devices do not adopt any expedient to compensate for a possible not correct position of the instrument before and/or during the measurement.

Moreover, the known devices do not guarantee sufficiently the operators’ safety, especially with respect to possible accidents which can occur due to the activation of the light emission.

Moreover, they do not succeed in performing reliable measurements in presence of optically not cooperating surfaces, such as for example optical units, panes, etc.

Technical problem solved by the invention

The object of the present invention is to solve the problems left unsolved by the known art, by providing an apparatus for the measurement of gap and flush between two surfaces, as defined in claim 1.

The present invention further relates to a measuring process as defined in claim 7.

Additional features of the present invention are defined in the corresponding depending claims.

The present invention involves several and evident advantages with respect to the known art.

In particular, the system according to the invention allows:

a) to provide feed-back to the operator by means of a man-machine interface showing if the system is positioned in the measurement position and at the correct working distance; this allows the operator to position correctly the measuring system;

b) to perform the measurement only if the system is positioned in the correct measurement position and at the correct working distance;

c) to perform the measurement on different materials and colours by adapting automatically the system parameters;

d) to make safe the use of a not shielded light source;

e) to return as output the measurement of gap and flush associated to the information of the position wherein the measurement has taken place.

Other advantages, together with the features and use modes of the present invention, will result evident from the following detailed description of some preferred embodiments thereof, shown by way of example and not for limitative purposes.

Brief description of the figures

The drawings shown in the enclosed figures will be referred to, wherein:

• figure 1 shows schematically the geometrical meaning of gap and flush;

• figure 2 schematizes the operation of an apparatus according to the known art;

• figure 3 is a schematization of a possible embodiment of an apparatus according to the invention;

• figures 4A and 4B are a schematization of a possible embodiment of an apparatus according to the invention;

• figures 5A and 5B show two possible use modes of an apparatus according to the invention; and

• figure 6 is a flow chart which describes a possible measuring procedure with the apparatus according to the invention.

The present invention will be described hereinafter by making reference to the above-mentioned figures. Detailed description of possible embodiments of the invention

With reference to figure 4A, generally a system according to the invention consists of a preferably portable apparatus 1 for measuring gap and/or flush between two surfaces 2, 3.

Such apparatus 1 comprises:

a light source 4 which produces a plane the projection thereof on the surfaces 2 and 3 generates the light profile 5;

at least a first camera 6, in case provided with suitable devices, such as for example interferential filters and/or polarizer, for reducing reflections or interferences from other light sources, arranged in such a way as to have a field of view 7 on the surfaces 2,3 wherein the light profile 5 is included and with a capturing optical axis AC tilted with respect to the lighting optical axis AL, as illustrated in figure 2;

at least a distance sensor 8 configured to measure the distance between the apparatus 1 and the surfaces 2, 3;

a starting device 1 1 for the activation of the apparatus’ functionalities that is of the measuring procedure;

a controller 9 adapted to acquire data from the distance sensor 8 and to control the activation of the light source 4 and of the camera 6, wherein said controller is configured to activate the light source 4 only if the functionalities of the apparatus 1 have been enabled by pressing the starting device 1 1 , the apparatus 1 is in the correct measurement position and the distance between the apparatus 1 and the surfaces 2, 3 is included in a predetermined interval DM.

Under“correct measurement position” it is to be meant that the apparatus is really positioned so as to be able to measure and/or flush on the wished surfaces (or on the portions of surfaces), and is not positioned instead so as to try to perform a measurement on surfaces of other objects and/or portions of surfaces different from the wished ones.

The verification of correctness of the measurement position, as it will be described in details, takes place by means of a classification procedure based upon the images acquired by the apparatus. Moreover, the controller 9 is adapted to acquire data from the first camera 6 and to process them to provide gap and/or flush values between the two surfaces 2, 3 based upon triangulation algorithms.

The measurement of gap and/or flush takes place by means of a triangulation system.

In particular it is based upon:

a) the projection of a light plane in direction approximatively orthogonal to the surfaces 2,3 and approximatively orthogonal to the space separating the portions which are measured;

b) the observation through the first camera 6 positioned with optical axis tilted with respect to the optical axis of the light source, as illustrated in Figure 2;

c) the acquisition of the data related to the image of the surfaces 2, 3 captured by the camera 6;

d) the image processing for identifying the light profile 5, and subsequent processing through a triangulation algorithm for measuring flush and an algorithm for detecting the profile interruption for gap.

The used algorithms will be not described in details as they can be considered within the comprehension of a person skilled in the art and they can be detected in the known art.

In a particular implementation of the apparatus, should the measurement of gap and/or flush be performed on smooth surfaces such as enamelled sheet and transparent portions (optical groups, panes), the light source 4 has to emit in a spectral range lower than 600nm. This also allows to optimize the signal-noise ratio of the image acquired by the camera 6. Preferably, according to some embodiments, the wavelength of the light source is included between 380 nm and 420 nm.

According to an additional embodiment, an apparatus according to the invention can further comprise an inertial measuring device 13 for detecting the orientation and a state of motion of the apparatus itself. Said inertial measurement device can be used both for improving the measurement quality, as shown in the known art, and for configuring the controller 9 so as to be able to activate the light source 4 only if the detected orientation corresponds to a predetermined orientation (light plane orthogonal to the measurement surfaces and light profile 5 orthogonal to the interstice between the surfaces 2, 3) and/or if said apparatus is stationary.

As already anticipated, it can be particularly advantageous to be able to recognize and classify the portions thereto the surfaces under examination belong.

To this purpose, the images acquired through the first camera 6 and provided to the controller 9 can be used, which controller will be configured to acquire the data related to the images captured by the camera and to process them to perform a recognition of the measurement position, a classification of the surfaces 2, 3 under examination, preferably by means of matching algorithms, and an adjustment of the exposition time of the first camera 6 depending upon the classes wherein the surfaces 2 and 3 are inserted.

If one was framing a position not included inside a database of images, suitably populated after a training procedure of the controller 9, for example a face or a not required position, the controller 9 could not activate the light source 4, notwithstanding a possible request for activation of the measuring procedure by the operator through the starting device 11 , but it could send a feed-back signalling to the operator by suggesting him/her to move in the correct measurement position.

Advantageously, according to some embodiments, as shown in Figure 4B, an apparatus according to the invention can further comprise a second camera 10 provided with its own lighting system 14 and possible devices for reducing interferences (reflections and/or external light sources) such as, for example, interferential filters and/or polarizers.

Such second camera 10 preferably is arranged so as to be able to capture the light profile 5 on the surfaces 2, 3 under examination, as well as the camera 6.

Even the second camera 10 could be connected to the controller 9 and, in these cases, the images for the classification can be those captured by the second camera 10. According to still additional embodiments, as shown in Figure 3, an apparatus according to the invention can further include interface means 12, whereon, for example, the measurement results are to be displayed, and/or devices for the connection with an external processor 15, for example for the transfer of the measurement data.

In particular, such interface and connection means can be of the wireless type.

According to additional embodiments, shown in Figure 5A and 5B, the device can be implemented in the portable form, so as to allow the operator to work remotely (Figure 5A) and/or in contact (Figure 5B) with the surfaces characterizing the wished measurement position.

Therefore, an apparatus according to the present invention is suitable to implement a corresponding process for measuring gap and/or flush between two surfaces 2, 3.

Such process comprises at least the steps of:

supplying a measuring apparatus 1 according to what described sofar; activating the functionalities of the apparatus 1 by means of the starting device 11 ;

performing a check on a predefined activation condition and, if said check is positive:

o activating the light source 4;

o acquiring data from a first camera 6; and

o processing the acquired data to provide gap and/or flush values between the two surfaces 2, 3 based upon triangulation algorithms.

Generally, the predefined activation condition comprises at least the need for:

• verifying the correctness of the framed measurement position;

• verifying if the distance between the apparatus 1 and the surfaces 2, 3 is included in a predetermined interval DM, useful for the measurement.

According to some embodiments the wavelength of the light source is included between 380 nm and 420 nm. Moreover, a process according to the invention can even include a step for detecting the orientation and/or a state of motion of the apparatus 1 , with the purpose of activating the light source 4 only when the detected orientation corresponds to a predetermined orientation and/or the apparatus 1 is stationary.

Moreover, the process provides a step of acquiring data from a camera, for example the first camera 6, arranged so as to capture the light profile 5 on the surfaces 2, 3 under examination and a consequent step of processing the acquired data to perform recognition and classification of the surfaces 2, 3 by means of matching algorithms.

This allows:

in case of positive result of the recognition and classification process, activating the light source 4 by adapting the exposition time of the first camera depending upon to which class the detected surfaces belong; in case of negative result of the recognition and classification process, providing a feedback through an interface means 12.

From all above then it can be deducted that, according to the described embodiments, the apparatus implements a measuring system - which can be produced in portable form - based upon the technique of triangulation with light plane and provided with features which make it“intelligent”. In particular, the presence of the described sensors allows it to perform, for example, functions such as:

a) recognizing and classifying the object portion (measurement position) whereon the apparatus is performing the measurement, in particular recognizing if it is measuring on sheet or on transparent portions, such as headlights, panes, etc.;

b) not activating the light source if the system is not directed to recognizable and measurable portions of the object, to guarantee operators’ safety by avoiding the possibility of direct radiation of the operator by the light source;

c) recognizing if and when the apparatus is inside an allowable range of measurement (interval of distances from the object), so as to enable the acquisition of the measurement only if the apparatus is positioned inside the allowed measurement range; d) not activating the light source if the apparatus is not positioned at a distance from the object to be measured comprised in the allowed range of distances, to guarantee operators’ safety by avoiding the possibility of direct radiation of the operator by the light source;

e) adapting the exposure parameters of camera/cameras to the different optical features of the surfaces through corresponding algorithms, with the purpose of maximizing the signal-noise ratio in the acquired images;

f) recognizing the orientation therewith the light source illuminates the surfaces under examination;

g) enabling the measurement only if the acceleration level is lower than a prefixed threshold to avoid acquiring with moving system;

h) recognizing the orientation of the apparatus in space;

i) providing as output the measured value of gap, the measured value of flush and the position whereon the measurement has occurred.

For example, with reference to figure 6, this shows a flow chart related to a possible embodiment of the measuring process.

When the apparatus is switched-on the light source is turned off, as well as the other sensors. When the activation of the measuring procedure is requested, for example through a starting device such as a button, the apparatus provides for evaluating on which position the measurement is being performed. The recognition of the measurement position takes place through the acquisition of an image, its subsequent processing and its classification by means of matching algorithms. The recognition of the measurement position can take place, for example, through a second camera existing in the system or through the same camera therewith the evaluation of gap and/or flush is performed. In case the system is framing a not requested measurement position, for example a face or measurement position not included in a database of the measuring positions suitably populated by means of a preliminary training procedure, a feedback is sent, on a dedicated interface, with the indications required to bring the device back to the correct measurement position.

Subsequently the distance between the system and the object to be measured is evaluated. The distance measurement takes place by means of the contactless distance sensor. Such sensor provides as output the distance, which is acquired and processed to verify if it falls within the allowed measurement range.

A visual feed-back is then provided, through an interface, wherein indications about the conditions of acceptability of the measurement distance are given; in case of negative verification, an indication about the motion direction (approaching or enlargement) is provided to be able to return within the acceptability range of the measurement distance itself.

Contemporary to the distance check, the stability condition of the apparatus is evaluated, though an inertial sensor.

In case of positive result of all above-mentioned conditions the light source is activated and one provides for measuring gap and/or flush between the two surfaces.

The present invention has been sofar described with reference to preferred embodiments thereof. It is to be meant that each one of the technical solutions implemented in the preferred embodiments, herein described by way of example, can advantageously be combined, differently from what described, with the other ones, to create additional embodiments belonging to the same inventive core and however all within the protective scope of the here below reported claims.

Claims

1. An apparatus (1) for measuring gap and/or flush between two surfaces (2, 3), comprising:

a light source (4), having a lighting optical axis (AL), which generates a light plane;

at least a first camera (6) arranged in such a way as to have the capturing optical axis tilted with respect to the lighting optical axis (AL) and to capture the light profile (5) on said surfaces (2, 3);

at least a distance sensor (8) configured to measure the distance between the apparatus (1) and said surfaces (2, 3);

a controller (9) adapted to acquire data from said distance sensor (8) and images from said at least first camera (6), and to control the activation of the light source (4),

wherein said controller (9) is configured to process the acquired images to perform recognition and classification of said surfaces (2, 3) by means of matching algorithms in order to verify the measurement position,

said controller (9) is configured to activate said light source (4) only if the measurement position is recognized as the correct position and the distance measured between the apparatus (1) and said surfaces (2, 3) is included in a predetermined interval (DM),

said controller (9) being further adapted to acquire data from said first camera (6) and process them to provide gap and/or flush values between said two surfaces (2, 3) based upon triangulation algorithms.

2. The apparatus (1) according to claim 1 , wherein the wavelength of said light is included between 380 nm and 420 nm.

3. The apparatus (1) according to claim 1 or 2, further comprising an inertial measuring device (13) for detecting the orientation and a state of motion of said apparatus (1).

4. The apparatus (1) according to claim 3, wherein said controller (9) is configured to activate the light source (4) only if said detected orientation corresponds to a predetermined orientation and/or if said apparatus (1) is stationary.

5. The apparatus (1) according to anyone of the preceding claims, further comprising a second camera (10) arranged in such a manner as to capture the light profile on said surfaces (2, 3).

6. The apparatus (1) according to claim 5, wherein said controller (9) is adapted to acquire data from said second camera (10) and use such data to perform said recognition and classification step in order to verify the measurement position.

7. The apparatus (1) according to anyone of the preceding claims, further comprising means for interfacing and/or connecting external apparatuses, preferably of the wireless type.

8. A process for measuring gap and/or flush between two surfaces (2, 3), comprising the steps of:

supplying a measuring apparatus (1) according to anyone of the preceding claims;

acquiring and processing images of said surfaces (2, 3) to perform recognition and classification of said surfaces (2, 3) by means of matching algorithms in order to verify the measurement position and, if said measurement position is recognized as correct position, to provide for:

o measuring the distance between the apparatus (1) and said surfaces (2, 3);

o performing a check on a predefined activation condition and, if said check is positive:

^■ activating the light source (4);

^■ acquiring data from a camera (6); and

^■ processing the acquired data to provide gap and/or flush values between said two surfaces (2, 3) based upon triangulation algorithms, wherein said predefined activation condition comprises: verifying if said distance is included in a predetermined interval (DM).

9. The process according to claim 8, wherein the wavelength of said light is included between 380 and 420 nm.

10. The process according to claim 8 or 9, further comprising a step for detecting the orientation and/or a state of motion of said apparatus (1).

11. The process according to claim 10, wherein said predefined activation condition comprises: verifying if said detected orientation corresponds to a predetermined orientation and/or if said apparatus (1) is stationary.