WO2019048743A1

WO2019048743A1 - Method for installing reference zones on a ground surface for calibrating cameras of a motor vehicle, and associated equipment

Info

Publication number: WO2019048743A1
Application number: PCT/FR2017/052401
Authority: WO
Inventors: Frederic Ferreira; Cedric HOLLART
Original assignee: Renault S.A.S.
Priority date: 2017-09-11
Filing date: 2017-09-11
Publication date: 2019-03-14

Abstract

The invention relates to a method for installing reference zones on a substantially flat horizontal ground surface for calibrating cameras of a motor vehicle (1), comprising: -the positioning of the vehicle (1) on the ground, wheels parallel to a longitudinal axis (X) of the vehicle, -the positioning of referencing equipment (10) on the ground around the vehicle, said referencing equipment (10) comprising a set of separate elongate plates that form rulers (11-18), this positioning being carried out by laying the rulers on the ground in a predetermined pattern, at a predetermined distance from the vehicle. Each ruler (11-18) has a flat lower face resting at least partially on the ground, an upper face having a referencing zone, and is sufficiently rigid to not deform in a plane parallel to the upper and lower faces. The invention also relates to the corresponding equipment.

Description

METHOD FOR INSTALLATION OF ZONES OF REPERAGE ON A SOIL FOR CALIBRATION OF CAMERAS OF A VEHICLE

AUTOMOBILE AND ADAPTIVE EQUIPMENT

The invention relates to a method of installing ground registration areas for the calibration of cameras of a motor vehicle and adapted equipment.

Many vehicles today are equipped with cameras to visualize the environment of the vehicle. In particular, a system called AVM (in English "Around View Monitor") makes it possible to create an image in top view of the vehicle by recomposing video images from at least 4 cameras, including a front camera, a rear camera, a left side camera, a right side camera. The reconstitution of the top view of the vehicle requires an electronic adjustment of the 4 cameras, this setting being learned in a computer dedicated to the AVM system with an electronic diagnostic tool. This setting may consist of an overlay adjustment of lines on a multimedia screen with a ground mark.

This adjustment (or calibration) is carried out at the factory, before the vehicle is put into service, but must also be able to be performed after-sales, for example when replacing one of the 4 cameras or parts supporting one of the cameras or when replacing the computer dedicated to the AVM. Thus, camera calibration should be done as soon as the bodywork or camera support parts have been touched or damaged as a result of shocks or accidents.

Camera calibration requires positioning of contrasting ground reference points and accurate positioning of the vehicle with respect to these reference areas. In the factory, the adjustment is usually carried out on a dedicated bench with a controlled light environment, the marks being permanently present on the ground.

In an after-sales workshop, setting up benchmarks can be problematic. One solution is to use adhesive strips applied directly to the floor. This solution is however hardly compatible with the state of the floors of a workshop and the positioning accuracy of these bands on the ground proves insufficient for perform the calibration correctly. In addition, the required floor area is relatively large and not always available, and the installation time is relatively long. It is also known to have only parallel white lines on both sides of the vehicle. This solution also requires a relatively large workshop area and these parallel lines do not always correspond to the benchmarks used in the factory, it is necessary to adapt the AVM computer. There are also solutions using one or more carpets on which markers are drawn. Nevertheless, this solution is generally used for a single vehicle template and it may be difficult to accurately position the vehicle on the carpet or with respect to carpets. In addition, again, it may be necessary to adapt the AVM calculator.

The aim of the invention is to overcome at least part of these disadvantages by proposing a method of installing marking zones on a substantially plane horizontal ground for calibrating the cameras of a motor vehicle, said installation method comprising:

the positioning of the vehicle on the ground, wheels parallel to a longitudinal axis of the vehicle,

locating locating equipment on the ground around the vehicle, said locating equipment comprising a set of distinct elongated plates forming rulers, each ruler having a lower planar face resting at least partially on the ground and an upper face having a contrasting detection zone detectable by the cameras and each rule being rigid enough not to deform in a plane parallel to the upper and lower faces, the positioning being achieved by placing the rules of the adjustment equipment on the ground according to a predetermined pattern at a predetermined distance from the vehicle.

The use of this type of rules makes it possible to overcome the state of the ground, especially when the latter is not perfectly flat, and to ensure the linearity of the marking. In addition, the rules are not fixed on the ground, they can be used in any place, in particular in after-sales or even in factory, if one does not wish to bring back the vehicle to the dedicated test bench . The installation of such tracking equipment is particularly suitable for calibrating the cameras of a vehicle comprising in particular at least one front camera, a rear camera, a left side camera and a right side camera.

The rules being distinct from each other, they can also be arranged according to various diagrams that may correspond to different diagrams used by different AVM computers: it is not necessary to modify a given computer for after-sales settings. .

In general, the marks used are parallel or perpendicular to the longitudinal direction of the vehicle. Also, advantageously, the rules of the adjustment equipment can be positioned perpendicularly or parallel to a longitudinal axis of the vehicle.

In this particular arrangement, but also for any other arrangement of the rules relative to each other, the rules may be distributed symmetrically with respect to a predetermined axis, for example with respect to a central longitudinal axis of the vehicle or relative to any other axis according to the AVM calculator.

In order to facilitate the relative positioning of the rulers with respect to the vehicle, it may be preferable to position at least two rulers in abutment against a wheel of the vehicle. Advantageously, a ruler may be disposed abutting on one wheel and another ruler disposed abutting on the other wheel of the same axle, preferably the front axle.

Other rules can also be arranged in abutment on the other wheels of the vehicle. Preferably, it is the end of the ruler which abuts against the wheel, the ruler extending parallel to the axis of the wheel, in other words parallel to the transverse axis of the vehicle.

Alternatively or in combination, during the positioning of the locating equipment, the relative positioning of the rules can be facilitated by the positioning of at least one wedge of predetermined dimensions between a wheel and a ruler. In particular, the dimensions of the shim can be chosen according to the predetermined distance between the marking areas and the vehicle. Preferably, the ruler extends parallel to the longitudinal axis of the vehicle and the shim extends perpendicularly to the ruler. The positioning of the locating equipment may include: positioning two rulers parallel to the longitudinal axis of the vehicle on each side thereof,

the positioning of two rulers perpendicular to the longitudinal axis of the vehicle in front of and behind the vehicle,

the positioning of a ruler on each side of the vehicle, perpendicular to the longitudinal axis, preferably in the axis of each of the front wheels,

the positioning of two rulers extending in the central longitudinal axis of the vehicle, in front of and behind it.

This provides locating areas on each side of the vehicle. Of course, other rules can be implemented depending on the predetermined pattern to be achieved.

The positioning of the rulers can be obtained simply by using a plumb bob and a square of appropriate dimensions.

In particular, the positioning of a ruler in the central longitudinal axis of the vehicle may be achieved by means of a plumb bob positioned on a central mark on the vehicle (for example, the logo of the mark at the front and at the back of the vehicle). The back or trunk release button at the back The positioning of a ruler in the axis of a wheel can also be achieved by means of a plumb bob.

The right angles between the rulers can be obtained by using a square sufficiently large for this purpose, in particular when the perpendicular rules are not in abutment.

The different rules can be put in position in any order, it may nevertheless be advantageous to position first the rules in abutment against the wheels and the lateral rules perpendicular to these rules abut against the wheels, possibly with the help of wedges arranged between these lateral rules and the other wheel.

In order to facilitate their adaptation to different vehicle templates, the rules of the adjustment equipment may be adjustable in length. It is then possible to choose the length of the rules so that at least part of the rules are against other rules, and whatever the size of the vehicles concerned, which can facilitate their positioning.

The invention also relates to a tracking device for calibrating external cameras of a motor vehicle comprising a set of distinct elongated plates forming rulers each having a lower planar face and an upper face having a registration area, in particular a contrasting detection area detectable by a camera, each rule being rigid enough not to deform in a plane parallel to the upper and lower faces.

Such equipment may in particular be used for the implementation of the installation method of the present invention.

The registration area is advantageously able to be detected by an optical camera. It may for example consist of one or more parts absorbing or reflecting the light radiation. It is thus possible to make a part of a different color from the rest of the ruler, for example black on a gray metal ruler, or to make several contrasting parts (black and white).

The registration area may consist of one or more rectilinear lines drawn on the upper face and extending over the entire length of the rule, parallel to the edges of the rule. The line or lines may be arranged symmetrically with respect to a longitudinal central axis of the rule.

In order to facilitate the positioning of the rules relative to each other and with respect to the vehicle, at least a portion of the rules may have at least one marking selected from a landmark and a graduation. The graduation may be a graduation extending along the length of the rule. The reference point (s) may be provided for different vehicle templates or different predetermined schemes.

To facilitate the use of rules, especially for vehicles of different sizes, the length of at least a portion of the rules can be adjustable. For this purpose, the rules may be telescopic or be formed of segments connected in pairs by any appropriate means (latching, interlocking, magnetization, ...).

The locating equipment may comprise non-parallel pairs of rules, optionally perpendicular, mounted slidably relative to each other. This can facilitate the positioning of the rules around a vehicle.

The invention is now described with reference to the appended non-limiting drawings, in which: - Figure 1 shows a top view of a motor vehicle equipped with cameras;

- Figure 2 schematically shows a top view of a vehicle and a tracking area;

- Figure 3 schematically shows a perspective view of a vehicle around which a tracking equipment is partially installed according to an embodiment of the mention;

- Figures 4 and 5 each show a perspective view of a rule of a tracking equipment according to different embodiments of the invention;

- Figure 6 shows a side view of a rule of a tracking equipment according to another embodiment.

FIG. 7 represents a perspective view of two rules of a tracking equipment according to another embodiment of the invention;

- Figure 8 shows a front view of a vehicle.

In the present description, the terms front, rear, upper, lower, refer to the front and rear directions of the vehicle. The X, Y, Z axes correspond respectively to the longitudinal (front to back), transverse and vertical axis of the vehicle.

FIG. 1 represents a view from above of a motor vehicle 1 equipped with four cameras 2, 3, 4, 5, respectively arranged in front of, behind, on the left lateral side and on the right lateral side. The areas bounded by dashed lines represent the shooting fields of each camera. Such a set of cameras 2-5 makes it possible to create an image in top view of the vehicle by recomposition of the images coming from the 4 cameras. Of course, it is also possible to display the images taken by each camera.

Recomposing the images requires calibrating the cameras. For this purpose, a predetermined frame of reference is generally used, defined by marking zones on the ground. This repository is predefined in a computer of an AVM system.

FIG. 2 represents an exemplary reference frame usable by a computer. In this figure, the vehicle 1 is shown schematically, as well as the front wheels 6 and 7. Note that the reference system has 4 crosses A, B, C, D: two crosses (A, B) arranged respectively at the front and rear of the vehicle and two crosses (C, D) arranged on each lateral side of the vehicle, at a height of a front wheel 6, 7. These crosses are each composed of a segment extending parallel to the longitudinal axis X of the vehicle and a segment extending parallel to the transverse axis Y of the vehicle.

This type of reference can be directly drawn on a horizontal plane of a dedicated area of a factory (test bench). The floor of an after-sales workshop is however much less regular in general, it can be difficult to achieve landmarks, including permanent, especially when space is limited.

In order to allow easy calibration of the cameras, the present invention proposes a tracking device 10 that can be easily used anywhere, and especially on the floor of a workshop or any other place.

FIG. 3 represents a tracking device 10 according to one embodiment of the invention, arranged around a vehicle 1. This marking equipment 10 has a set of distinct elongate plates forming rules referenced from 1 1 to 18.

It will be noted that these rules present here rectilinear edges perpendicular to each other. In other words, each rule has a rectangular shape whose length is much greater than the width.

The rules are substantially identical and differ essentially in their length.

Each rule 1-18 is furthermore sufficiently rigid not to deform in a plane parallel to the upper and lower faces. These rules may be metal, for example aluminum, steel or other metal alloy, or be in a polymeric material, or metal material coated with polymeric material, provided they have the desired rigidity.

Various rule embodiments are described with reference to FIGS. 4-7.

As shown in FIG. 4, one or more rules 1 - 18 may be graduated along their length, or may include markers.

In the embodiment shown in FIG. 4, the rule 1 1 has a lower plane face 11a and an upper face 1b having a marking area 1 1c, here a straight black band (symbolically represented by hatching). This upper face 1 1b is preferably flat, but non-planar faces are possible, provided that an optical camera can distinguish the registration area.

The registration area formed in the illustrated example of a single black band is centered with respect to the width direction of the rule. The ratio of the width of the black band to the width of the ruler is typically 1/3 to 1/2.

The contrasting registration zone is here constituted by the black color and the dark appearance of the strip which is framed by adjacent longitudinal edges of the ruler, here typically of aluminum aspect (unpainted).

FIG. 5 represents an embodiment in which a rule 11 is formed of several sections 121, 122 which slide one inside the other along their longitudinal direction. This adjusts the length of the ruler. Each section 121, 122 carries a registration area 121c, 122c, here in the form of a straight black line. The lower wall 123 of the section 122 can then be relatively thin (for example 1cm or less) so that the difference in level between the lower face 121a and the lower face 122a is relatively small when the two sections rest on the ground.

Figure 6 shows another embodiment in which a rule 21 1 is formed of several sections 221, 222 nested within each other. The invention also extends to any other embodiment allowing adjustment of the total length by relative sliding between the sections.

In the embodiments shown in FIGS. 5 and 6, each section has a rectangular shape in a horizontal plane. Of course, the invention is not limited to a particular number of sections. Note that the connection means of the different sections are preferably arranged so that the registration areas coincide from one section to another and that the rule is rectilinear over its entire length.

Figure 7 shows an embodiment in which two rulers 31 1 and 312 are slidably mounted relative to each other, being perpendicular to each other. For this purpose, a ruler 313 sliding on the first rule 31 1 may be provided, the second rule 312 being slidably mounted on the strip 313. Of course, any other type of slide connection may be provided. It can also be expected that only one rule can slide relative to the other and or the rules do not cross at a right angle but at another predetermined angle.

The different embodiments of the rules described above can be combined with each other. In addition, equipment according to the invention may include rules of different embodiments.

The installation of the marking areas by means of the equipment 10 according to the invention is now described with reference to FIGS. 3 and 8. The rules 11 to 18 are as shown in FIG. 4.

In the illustrated example, the rules 18 or 14 according to the visual reference frame have a minimum length of 1250 mm.

Rules 17 or 13 according to the visual reference system have a minimum length corresponding to the width of the vehicle increased by 600 mm, ie for a Renault Clio ® type vehicle approximately 2600 mm in total.

The width of the rulers is typically of the order of 100 mm.

In these figures, the vehicle 1 rests on a substantially flat horizontal ground.

By substantially plane means a surface having asperities of at most 5 cm in height, preferably at most 4 cm in height.

The front driving wheels 6, 7 of the vehicle 1 are positioned parallel to the longitudinal axis X of the vehicle.

A wheel parallel to an axis means that the plane of the wheel is parallel to an axis or that the axis of rotation of the wheel is perpendicular to this axis. Thus, wheels are parallel to a longitudinal axis of a vehicle when they are "straight" and a plane containing the wheel does not form an angle with a longitudinal vertical plane of the vehicle.

Once the vehicle is positioned, the marking equipment 10 can be placed on the ground around the vehicle, here in a diagram corresponding substantially to the diagram of FIG. 2. The different rules can be arranged as follows:

a first rule 1 1 is positioned along the length of the vehicle, parallel to the longitudinal axis X. For this purpose, the end of a shim 19 is placed in abutment against the rear wheel 8 perpendicular to the rule 1 1 and the end of a second rule 12 is positioned in abutment against the front wheel 6 also perpendicular to the first rule January 1.

A third rule 13 is then positioned in front of the vehicle parallel to the transverse axis Y. For this purpose, it is placed at right angles to the first rule January 1.

A fourth rule 14 is positioned perpendicular to the third rule 13, in the central longitudinal axis X of the vehicle. To do this, a plumb line 20 can be stretched from a central reference 21 of the vehicle, as shown in FIG.

A fifth rule 15 is then placed on the length of the vehicle, on the other side of the vehicle relative to the first rule 1 1, perpendicular to the third rule 13. Possibly a wedge abutting (not visible in the figure) against the rear wheel can be used to facilitate the establishment of the rule.

A sixth rule 16 is positioned perpendicular to the rule 15, in the axis of the other front wheel.

A seventh rule 17 perpendicular to the first and fifth rules 1 1 and 15 is then positioned at the rear of the vehicle.

Finally, an eighth rule 18 is positioned perpendicularly to the seventh rule 17, also in the central longitudinal axis of the vehicle, as rule 14.

The different rules intersect at a predetermined distance from the vehicle, chosen according to the calculator used.

Alternatively, the first rule 1 1 could be implemented without the help of the wedge 19. It may then be advantageous to position the rules 1 1 and 15 on each side of the vehicle and the rules 12 and 16 abut against the front wheels, then ensure their parallelism to the longitudinal axis by positioning one of the rules 13 or 17 at right angles to each of the rules 1 1 and 15.

It will be noted that the locating equipment 10 is positioned in FIG. 6 so that one part of the rules abuts against another rule. Here, the rules 1 1 and 17 are in abutment with the rules 1 1 and 15, the rules 1 1, 13, 15 and 17 forming a kind of frame around the vehicle 1. This can facilitate the control of the angle between these rules, especially by means of a bracket 22 shown in Figure 3. However, it is not necessary that the rules abut against the adjacent rule for adjusting the angle, it is sufficient that the bracket 22 is sufficiently long to be put in support against the two rules to position perpendicularly.

Each rule being rigid enough not to deform in a plane parallel to its upper and lower faces, it is understood that even placed on uneven ground, the lower face not then resting entirely on the ground due to irregularities thereof , the rule remains rectilinear, which allows the use of the registration area for camera calibration. It is the same when the lower face of a rule is not strictly flat, for example in the case of intersecting rules or rules composed of segments.

The invention has been described for the implementation of rules oriented along longitudinal and transverse directions. The rules of the marking equipment according to the invention can nevertheless be arranged relative to each other at non-right angles. Angle measuring tools can then be used, such as backers or corner tools forming the required angle. It is thus understood that the equipment according to the invention can be used for any type of scheme. It can also be set up easily and quickly anywhere. Finally, it can be set up for different vehicle templates, especially when at least some rules are of adjustable length.

Claims

A method of installing registration areas on a substantially level horizontal ground for calibrating the cameras of a motor vehicle (1), said installation method comprising:

positioning the vehicle (1) on the ground, wheels parallel to a longitudinal axis (X) of the vehicle,

positioning a tracking device (10) on the ground around the vehicle, said tracking equipment (10) comprising a set of distinct elongated plates forming rulers (1 to 18), each ruler (1 to 18) having a lower planar face (11a) resting at least partially on the ground and an upper face (11b) having a contrasting detection area (11c) detectable by the cameras and each rule (1-18) being sufficiently rigid so as not to deform in a plane parallel to the upper and lower faces, the positioning being achieved by placing the rules of the adjustment equipment on the ground according to a predetermined pattern, at a predetermined distance from the vehicle.

2. Installation method according to claim 1, wherein the rules (1 to 18) of the adjustment equipment are positioned perpendicularly or parallel to a longitudinal axis (X) of the vehicle, optionally distributed symmetrically with respect to an axis longitudinal center of the vehicle.

3. Installation method according to claim 1 or 2, wherein is positioned at least two rulers (12, 16) abutting against a wheel (6) of the vehicle.

4. Installation method according to any one of claims 1 to 3, wherein at least one shim (19) of predetermined dimensions is positioned between a wheel (8) and a ruler (1 1) during the positioning of the tracking equipment.

5. Installation method according to any one of claims 1 to 4, wherein the positioning of the tracking equipment comprises:

positioning two rulers (1 1, 15) parallel to the longitudinal axis of the vehicle on each side thereof, the positioning of two rulers (13, 17) perpendicular to the longitudinal axis of the vehicle in front of and behind the vehicle,

positioning a ruler (12, 16) on each side of the vehicle, perpendicular to the longitudinal axis, preferably in the axis of each of the front wheels,

positioning two rulers (14, 18) in the central longitudinal axis of the vehicle, in front of and behind the vehicle.

6. Installation method according to any one of claims 1 to 5, wherein the length of the rulers (1 to 18) is adjustable, this length being chosen so that at least a portion of the rules are in abutment against other rules.

7. Tracking equipment (10) for calibrating external cameras of a motor vehicle comprising a set of distinct elongate plates forming rulers (1 to 18) each having a lower planar face (11a) and an upper face ( 1 1b) having a marking area (1 1c), each rule being sufficiently rigid not to deform in a plane parallel to the upper and lower faces.

8. Tracking equipment (10) according to claim 7, characterized in that at least a portion of the rules has at least one marking selected from a landmark and a graduation.

9. Tracking equipment (10) according to claim 7 or 8, characterized in that the length of at least a portion of the rules is adjustable.

10. Tracking equipment (10) according to any one of claims 7 to 9, characterized in that it comprises pairs of non-parallel rules between them, optionally perpendicular, mounted slidably relative to each other.