IT201800002746A1 - Method and apparatus for the dynamic calibration of electromagnetic devices for driving a vehicle. - Google Patents

Description

"Method and apparatus for the dynamic calibration of electromagnetic devices for driving a vehicle".

The present invention relates to an apparatus and a method for the dynamic calibration of electromagnetic devices for driving a vehicle.

As "electromagnetic devices" for driving aids, we mean here both devices emitting electromagnetic waves (such as headlights), and devices receiving electromagnetic waves (such as on-board cameras), and receiving-transmitting devices (which transmit and receive ) electromagnetic waves (such as on-board radar and LIDAR).

Commonly, these electromagnetic driving aid devices must be subjected to appropriate calibration, both in the initial installation phase and, periodically, in the maintenance phase.

Calibration here means the operation of checking and possibly correcting the alignment of a device to the vehicle's axis of advancement as well as, possibly, the correspondence, in terms of direction, intensity and quality of emission and / or reception of the device, to predetermined parameters.

For example, in the case of the vehicle's headlights, these must be correctly oriented both to allow illumination of the road and to avoid dazzling other road users.

Even in the case of cameras or radars (for example to detect and / or signal the presence of obstacles on the vehicle's trajectory or the lines that delimit the carriageway) it is necessary that they are correctly oriented, i.e. correctly aligned with the vehicle's forward axis. , in order to perform its function correctly.

The common problem in aligning these devices is the determination of the correct correspondence between the reference system integral with the vehicle, to which the electromagnetic devices refer, and a reference system of the environment in which the vehicle is located, in which they are located. the external elements, the other vehicles, the pedestrians, the road.

To this end, calibration devices have been created over time for electromagnetic driving aid devices that can be used to determine the correct orientation of these electromagnetic devices.

In general, the calibration devices of electromagnetic driving aid devices allow at least one step to check the alignment of the aforesaid electromagnetic devices, in some cases, however, they also actively intervene to correct this orientation.

To carry out a correct and precise measurement of the alignment, the reference system attached to the calibration device must correspond to the one attached to the vehicle.

In practice, however precise the calibration device of the driving aid devices may be, the accuracy of its readings, and consequently of the alignment of the devices, is affected by the incorrect alignment of the instrument itself to the vehicle's advancement axis.

The problem therefore arises of accurately determining the axis of advancement of the vehicle and verifying the alignment of the calibration device to this axis.

Today the most common type of systems for aligning the calibration device to the vehicle's axis of advancement is of the "static" type (the vehicle's advancement axis is approximated with the vehicle stationary in a single position) and provides for the use of a laser line generator coupled integrally to the calibration device. In these known systems, the calibration device is rotated together with the laser until the latter intercepts two symmetrical elements of the vehicle body taken as a reference point (for example two engine fixing bolts).

There are various devices on the market for aligning a calibration device to the axis of advancement of a vehicle, but not all of them prove to be optimal for determining the correct direction of advancement: for example, a common limitation is that when the support surface of the vehicle does not exactly correspond to the plane orthogonal to the gravitational acceleration, the alignment could be wrong, as for the measurements that require an effective evaluation of the direction of advancement, the difference between the two planes cannot be neglected.

There is also a general problem when using several distinct measurement systems, for example an apparatus for measuring the alignment to the vehicle's advance axis separate from a tool for checking the alignment of the headlights, since it is also necessary to determine the correspondence between the reference systems of the different measuring devices.

Other alignment apparatuses currently in use provide that the alignment of the calibration device is performed "on sight" by an operator, for example by centering laser beams emitted by the instrument at reference points on the vehicle body.

In this case the alignment is rather approximate and varies according to the precision of the operator, furthermore the vehicle body is not a reliable reference for identifying the vehicle's axis of advancement.

There are also "dynamic" alignment systems, referred to in the present description, in which, in short, the actual trajectory of the vehicle is verified.

A dynamic alignment system is, in principle, more precise than a static one, as it allows to detect the real axis of advancement of the vehicle.

However, since, normally, the detection of the vehicle's trajectory is carried out through successive static measurements, the above limits of the individual static measurements have repercussions on the dynamic alignment system.

Naturally these problems are applicable in a completely analogue line to all calibration devices of electromagnetic driving aid devices (eg instruments for controlling the alignment of radars and cameras).

The main aim of the present invention is to provide an apparatus and a method for the calibration of electromagnetic devices for driving a vehicle which solve the technical problem described above, overcome the drawbacks and overcome the limits of the prior art, allowing precise alignment. to the axis of advancement of a vehicle of a calibration device for electromagnetic driving aids.

Within this aim, an object of the present invention is to provide such a method and a related apparatus that are able to obtain greater precision as well as simplify measurements.

Another object of the invention is to give the greatest guarantees of reliability and safety in use.

Another object of the invention is to provide such a method and a relative apparatus which are easy to carry out and economically competitive if compared to the known art.

The aforementioned aim, as well as the aforementioned objects and others which will become clearer hereinafter, are achieved by a method according to claim 1.

This aim and these and other objects are also achieved by an apparatus according to claim 7.

Further characteristics and advantages will become clearer from the description of a plurality of preferred, but not exclusive, embodiments of an apparatus for the calibration of electromagnetic devices for driving a vehicle, illustrated by way of non-limiting example with the aid of attached drawings in which:

Figure 1 is a schematic representation from above of a possible embodiment of an apparatus for calibrating electromagnetic driving aid devices, according to the invention, with the vehicle in a condition of alignment;

Figure 2 is a schematic representation from above of the apparatus of Figure 1 in a condition of non-perfect alignment;

Figure 3a is a perspective view of the apparatus of Figure 1 with the vehicle in a first position;

figure 3b is a schematic representation from above of some elements of figure 3a;

Figure 3c is a side elevation view of the reference surface in the condition of Figure 3a;

Figure 4a is a perspective view of the apparatus of Figure 1 with the vehicle in a second position;

figure 4b is a schematic representation from above of some elements of figure 4a;

Figure 4c is a side elevation view of the reference surface in the condition of Figure 4a;

Figure 5 is a side elevation view of a possible embodiment of the apparatus, according to the invention, with the vehicle in a condition of non-alignment with respect to the horizontal plane

Figure 6 is a schematic representation of a possible embodiment of a laser emitter of the apparatus according to the invention.

With reference to the aforementioned figures, the apparatus for calibrating electromagnetic driving aid devices, globally indicated with the reference number 10, comprises a calibration device 20 for one or more driving aid devices.

This calibration device 20 can consist of any known instrument for checking the alignment and / or for the alignment and / or for the calibration of driving aid devices, such as for example headlights, radar or lidar for detection. of obstacles, optical data acquisition devices (such as cameras or scanners), etc.

In some embodiments the calibration device is constituted by a multifunctional instrument capable of carrying out the calibration of several devices at the same time.

In practice, the calibration device 20 must be understood as any instrument known in the art which, in order to perform its function correctly, needs to be aligned with the advancement axis of a vehicle.

In the non-limiting example described here, the calibration device 20 consists of an instrument for checking the alignment of the headlights.

More in detail, the instrument for controlling the alignment of the headlights taken as an example comprises a box-like body comprising in turn a detection panel 21 and a lens (not shown) which focuses the light coming from the headlights onto the detection panel 21.

The operation of this type of instrument is known in itself and provides, in short, to position the instrument in front of the headlight whose alignment you want to check and align it to the advancement axis v of the vehicle a; at this point the light of the spotlight focused on the detection panel 21 can be compared with reference graphic signs (or masks).

Alternatively, the detection panel 21 can be replaced by a camera and the control of the light beam performed by a computer control system connected to the camera.

In another possible embodiment not shown, the calibration device 20 consists of an instrument for checking the alignment of the cameras of a motor vehicle, for example of the type comprising a panel that is placed in front of the vehicle and aligned to the direction of advance v of the same. The panel bears an image, made up of graphic reference marks, which is captured by the camera. By comparing the image taken by the camera with the real image on the panel, the alignment of the camera is evaluated.

In another possible embodiment not shown, the calibration device 20 is constituted by an instrument for checking the alignment of the radar which comprises a reference target object (or "target") which is temporarily mounted on the radar using check points integral with the radar itself and a system for detecting the positioning of the target aligned with the direction of advance v of the vehicle a.

The radar orientation is identified and corrected if necessary by means of the target positioning detection system.

In practice, in this embodiment, the block indicated in the figure with the reference number 20 is constituted by the system for detecting the positioning of the target, while the target is mounted on the vehicle a.

According to the invention, the apparatus 10 further comprises: a laser emitter 50 and at least one and preferably two reflecting elements 30a, 30b for the reflection of at least one laser beam 51 emitted by the laser emitter 50.

The laser emitter 50 is constituted by any laser of a known type, preferably of the type comprising a source 52 (such as for example a HeNe source) and suitable optical components (such as for example one or more lenses).

In a first embodiment, the laser emitter 50 is configured to emit a horizontal laser line, i.e. a beam with maximum divergence, preferably greater than 90 ° and tending to 180 °, along the horizontal axis X and substantially zero ( compatibly with the limits of the prior art) along the vertical axis Y.

Preferably, in this embodiment (represented for example in Figures 3b and 4b), the laser emitter 50 comprises a laser source 52 and an optical element 56 which diverges, along the horizontal axis X, the emitted laser beam 51, such as for example a cylindrical lens.

In a second embodiment, the laser emitter 50 is configured to emit a beam which scans along the horizontal axis x, i.e. a beam 51 whose emission angle along the horizontal plane varies cyclically from a maximum value to a minimum value.

An example of this second possible embodiment of the laser emitter 50 is illustrated in Figure 6 and comprises a laser source 52, a movable optical element 54 which reflects the emitted laser beam 51, such as for example a rotating mirror and preferably also a fixed mirror 55.

In a further possible embodiment not shown, the laser emitter 50 is configured to emit a plurality of laser beams 51 and preferably a laser beam 51 for each reflecting element 30a, 30b.

Optionally, all the embodiments of the apparatus also include one or more optical elements (not shown) to make the measurements more precise, according to the known art, such as for example a lens which focuses the reflected laser beam 51 'on the reference surface. 60.

The reflective elements 30a, 30b are configured to be coupled to the bodywork of a vehicle. By bodywork of a vehicle we mean, in a very general way, the set of all the elements that make up the exterior of the vehicle and which, during travel, translate and curve in an integral way with the body and with the electromagnetic devices for driving aids. .

In the preferred and illustrated embodiment, the reflecting elements consist of levelable reflectors comprising a base 33 equipped with a suction cup or a magnet for fixing to the vehicle body.

Even more preferably, these bases 33 are adjustable so as to be able to align the reflecting elements 30a, 30b on the same horizontal plane, compensating for the inclinations and irregularities of the bodywork.

In other words, these bases 33 are advantageously adjustable in such a way that the reflecting elements 30a, 30b can be aligned at the same height and having parallel vertical axes.

In some embodiments, the reflecting elements 30a, 30b comprise at least one reflecting surface with a reflective section that is not constant along the vertical axis, so that an incident laser beam is reflected with different divergences or widths when it is incident at different heights. Preferably, in this embodiment, such reflecting elements 30a, 30b comprise at least one curved reflecting surface with a non-uniform angle of curvature along the vertical axis, so that a laser beam 51 incident on the reflecting element is reflected by it. with a different angle of divergence depending on the height (ie the position along the vertical axis) at which this laser beam 51 strikes the reflecting element 30a, 30b.

For example, in one of these possible embodiments, such as the one illustrated in fig. 5, the reflecting elements 30a, 30b have a substantially conical or frusto-conical shape with the reflecting outer surface.

Equivalently, the reflecting elements 30a, 30b can have the shape of a cone section.

In the case of conical or frusto-conical reflecting elements 30a, 30b, an incident laser beam 51 will be reflected with divergence along the minor horizontal axis X at higher altitudes and more precisely the divergence along the horizontal axis X will be inversely proportional to the altitude at which the laser beam 51 affects the reflecting element 30a, 30b itself (since the intercepted cone section will be smaller at higher altitudes).

In other embodiments not illustrated, the reflecting element 30 is provided with other types of reflecting elements known in the art, such as for example a total reflection prism or the like.

The apparatus 10 then comprises an alignment device 61, which in turn comprises a reference surface 60 on which the laser beam 51 'reflected by the reflecting elements 30a, 30b impacts.

The alignment device 61 performs the function of detecting, in a manner that will be clarified in detail below, the misalignment w, w 'of the calibration device 20 from the advancement axis v of the vehicle a at least as a function of points b1, c1, b2, c2 of incidence on the reference surface 60 of the laser beam 51 'reflected by the reflecting elements3 0a, 30b, with the vehicle a initially in a first position and, subsequently, in a second position reached by advancing the vehicle along the axis progress v.

The point of incidence b1, c1, b2, c2 of the reflected laser beam 51 'means the coordinates xb1, xc1, yb1, yc1, xb2, xc2, yc2, yb2 of the point where the laser beam 51' hits the reference surface 60, or the distance of that point from one or more reference points. When the reflected laser beam 51 'has a non-negligible divergence, this reflected laser beam 51 "affects the reference surface 60 with an image I, or imprint, characterized by a certain shape and surface. In this case with the point of incidence b1, c1, b2, c2 means any conventional point and preferably the geometric center of the image I.

When the reflected laser beam 51 'has a non-negligible divergence along the horizontal X axis and a negligible divergence along the vertical Y axis, as in the case of conical reflective elements 30a, 30b, this reflected laser beam 51' affects the surface of reference 60 with an image I having the form of a linear segment having a certain width d11, d12, d21, d22. In this case, the point of incidence b1, c1, b2, c2 means the midpoint of this segment.

It is anticipated here that this detection of the misalignment w of the calibration device 20 from the advancement axis v of the vehicle a takes place in an easier way thanks to an optional and advantageous feature of the invention consisting in the fact that the alignment device 61 and the calibration device 20 are in solidarity with each other.

The expression "misalignment w of the calibration device 20 from the axis of advancement v of the vehicle a" means the deviation, for simplicity expressed in terms of angle, of the axis of advancement v of the vehicle a with respect to the orientation that l axis v has itself when the vehicle a is perfectly aligned with the calibration device 20.

For the sake of clarity, it is specified that from now on, unless otherwise specified, whenever we speak of the orientation of an axis with respect to a plane or of an angle formed between an axis (or a plane) and a plane (or an axis) it is meant the plane angle formed by the projections of these axes / planes on the ideal horizontal plane 101 on which both the vehicle and the calibration device 20 rest. According to the invention, in fact, the vehicle a and all the other devices that make up the apparatus 10 are preferably positioned on the same substantially flat surface, such as for example a metal plate or a floor.

The condition of perfect alignment of the vehicle a to the calibration device 20 is illustrated in Figure 1.

It is also useful to specify that the "axis of advancement v of the vehicle a" is understood to mean the straight line along which the vehicle moves a when the driving wheels are activated.

In the example in which the calibration device 20 is an instrument for checking the alignment of the headlights, with particular reference to Figure 2, the reference surface 60 is parallel to the detection panel 21, so that the angle w that the advancement axis v of the shaped vehicle with the normal s to the reference surface 60 is the same f that forms with the normal to the detection panel 21 of the calibration device (w = f) and therefore the misalignment w of the axis of advancement of the vehicle v detected with respect to the reference surface 60 corresponds to the misalignment f of the axis of advancement v of the vehicle a with respect to the detection panel of the calibration device 20.

A measure of the angle w formed by the axis of advancement of the vehicle v and the normal to the reference surface 60 represents a measure of the misalignment of the calibration tool 20 with respect to the axis of advancement of the vehicle v: perfect alignment occurs when this angle w is null.

Therefore, by synthesis, from now on with "determining (or measuring) the misalignment w of the advancement axis v of the vehicle a with respect to the calibration device 20" is meant to determine (or measure) the angle w that the axis of advancement v of the shaped vehicle with the normal s to the reference surface 60.

In one embodiment, the misalignment w 'of the vehicle a with respect to the ideal horizontal plane 101 will also be taken into consideration, ie the angle that the real plane 102 on which the vehicle rests in shape with the ideal plane 101 perfectly horizontal.

Preferably, the alignment device 60 comprises at least one optical sensor for detecting the points b1, b2, c1, c2 of incidence of the laser beam 51 'on the reference surface 60 and a trajectory detection unit 62 which determines the misalignment w, w 'of the calibration device 20 from the axis v of advancement of the vehicle a as a function of at least the coordinates of the points b1, c1, b2, c2 of incidence of the reflected laser beam 51' on the reference surface 60 detected by the optical sensor.

More in detail, the optical sensor can, for example, consist of a matrix of photodiodes each capable of transforming a light signal with a frequency equal to the emission frequency of the laser source 50 into an electrical signal.

In other words, the optical sensor, in some embodiments, can be constituted by a camera.

Preferably, the optical sensor is integrated in the reference surface 60, or the reference surface 60 coincides with the optical sensor itself.

In another possible embodiment, in which the calibration device 20 is constituted by an instrument for controlling the alignment of the headlights comprising a camera for detecting the light emitted by the headlights, the optical sensor for detecting the points b1 , b2, c1, c2 of incidence of the laser beam 51 'on the reference surface 60 is constituted by the optical sensor of this camera and the reference surface 60 also coincides with, or in any case is coplanar with, said optical sensor.

Optionally, the alignment device 61 also comprises a distance measurement device (not illustrated) configured to measure the distance between the reference surface 60 and the reflective elements 30a, 30b.

This distance measuring device is constituted by any distance measuring system known in the art, such as for example a laser, time-of-flight or triangulation distance meter.

According to an optional and advantageous feature, the laser beam used by the laser distance meter is the same 51 emitted by the laser emitter 50.

The trajectory detection unit 62, when present, is constituted, for example, by a computer system equipped with software capable of processing the readings made by the optical sensor, and possibly by the distance measurement device, to determine a measurement of the misalignment w, w 'of the calibration device 20 with respect to the axis of advancement v of the vehicle a, according to the method that will be clarified hereinafter.

In a simplified embodiment, in which the trajectory detection unit 62 is not present, the processing of the readings made by the optical sensor, and possibly by the distance measuring device and the determination of the measure of the misalignment w of the calibration device 20 with respect to the axis of advancement v of the vehicle a, are performed by an operator, again in accordance with the method which will be further clarified hereinafter.

The measurement of the misalignment w of the calibration device 20 with respect to the axis of advancement v of the vehicle a is used to obtain a better calibration of the electromagnetic driving aid devices with respect to the known art.

In fact, according to the invention, once the measure of the misalignment w, w 'of the calibration device 20 with respect to the advancement axis v of the vehicle a has been determined, the electromagnetic driving aid devices are calibrated by means of the calibration device. 20 by compensating for the misalignment w, w 'of the axis of advancement v of the vehicle a with respect to the calibration device 20.

In one embodiment, the compensation of the misalignment w, w 'of the axis of advancement v of the vehicle a with respect to the calibration device 20 consists in modifying the orientation of the calibration device 20 with respect to the vehicle a so that the misalignment w, w 'of the axis of advancement v of the vehicle a with respect to the calibration device 20 is zero.

In practice, in this embodiment, the calibration device 20, the alignment device 61 (and optionally also the laser source 50) are housed in a single body 63 which can be rotated around a vertical guide 81, for example by means of a suitable rotation support. In this way it is possible to rotate the body 63 around the vertical axis y until reaching a position in which the detected misalignment w, w 'is zero and thus obtain the alignment of the calibration device 20 to the advancement axis v of the vehicle a.

In another embodiment, the compensation of the misalignment w of the advancement axis v of the vehicle a with respect to the calibration device 20 consists in correcting the readings made by the calibration device 20 as a function of the misalignment w, w 'of the axis advancement v of the vehicle a with respect to the calibration device 20.

In other words, in this latter embodiment, the calibration device 20 is configured, by means of an appropriate computer system, to correct the readings it has made as a function of the misalignment w, w ', in such a way as to make the errors null. due to this misalignment w, w '.

For example, in an embodiment in which the calibration device 20 is constituted by an instrument for controlling the alignment of the headlights comprising a camera and a computer control system for controlling the light beam connected to the camera, the computer control system it is configured to correct the measurements made as a function of the measurement of the misalignment w, w '(communicated to it by the trajectory detection unit 62 or by an operator).

In a possible variant of this embodiment, the trajectory detection unit 62 and the computer control system for controlling the light beam connected to the camera are advantageously integrated in a single computer system.

Advantageously, the alignment device 61 and the calibration device 20 are mutually integral and configured to translate along two axes x, y perpendicular to each other.

In this way the reference systems of the alignment device 61 and of the calibration device 20 coincide and therefore the alignment of the alignment device 61 to the advancement axis v of the vehicle a will ensure the simultaneous alignment of the calibration device with the utmost precision. 20 to the same axis v.

In the preferred and illustrated embodiments, the alignment device 61 and the calibration device 20 are housed inside a single body 63 constrained to a vertical guide rod 81, along which this body 63 slides. This vertical guide rod 81 is in turn constrained to a rectilinear horizontal guide 83 perpendicular to the vertical guide rod 81 itself and lying on the same plane 101 where the vehicle a rests.

Optionally, the laser emitter 50 is also integrated into the body 63.

Alternatively, as in the embodiment illustrated in figures 3a and 4a, the laser emitter 50 is fixed to the vertical guide rod so as to move integrally with the body 63 along the horizontal axis.

Preferably, the horizontal guide 83 consists of a pair of tracks and the vertical guide rod 81 is constrained to it by means of a carriage 82; alternatively, a guide-slide system or other equivalent system can be adopted.

In practice, by sliding the body 63 along the vertical guide rod 81 it is possible to adjust the position of the body 63 along the vertical axis y and by translating the carriage 82 along the horizontal guide 83 it is possible to adjust the position of the body 63 along the horizontal axis x.

In this way it is possible to translate the laser emitter 50 and the reference surface 60 to carry out the measurements described below without changing the orientation of the calibration device 20 with respect to the advancement axis v of the lane a.

Furthermore, once the calibration device 20 has been aligned with the axis of advancement v of the vehicle a, it is possible to carry out the alignment of electromagnetic driving aid devices positioned in different areas of the vehicle a (for example the right headlight and of the left headlight) by simply translating the body 63 along the guide 83, without having to repeat the alignment.

As already mentioned, according to the invention, the misalignment w of the advancement axis v of the vehicle a with respect to the calibration device 20 is determined as a function of the points b1, c1, b2, c2 of incidence on the reference surface 60 of the laser beam 51 'reflected by the reflecting elements 30a, 30b (at least by one and, in the preferred embodiment, by two reflecting elements 30a, 30b).

Preferably, the misalignment w is determined as a function of the two points b1, c1 of incidence on the reference surface 60, of the laser beam 51 'reflected by the first reflecting element 30a and by the second reflecting element 30b with the vehicle in the first position and the two points b2 , c2 of incidence on the reference surface 60, of the laser beam 51 'reflected at least by the first reflecting element 30a and by the second reflecting element 30b with the vehicle a in the second position;

The method by which the calibration is carried out, according to the invention, is briefly described below, with particular reference to the preferred embodiments in which two reflecting elements 30a, 30b are present.

The reflective elements are coupled to the vehicle a, for example by attaching them to the hood or roof.

With the vehicle stationary in a first position, in front of the calibration device 20, a laser beam 51 is emitted by the laser emitter 50 in the direction of the reflecting elements 30a, 30b.

In the embodiments in which the laser emitter 50 is configured to emit a laser line, this laser line is directed in such a way as to be reflected on the reference surface 60 by both reflecting elements 30a, 30b, thus forming two images I, I '.

In the embodiments in which the laser emitter 50 is configured to emit a beam which scans along the horizontal axis X, this scanning is performed in such a way that the laser beam 51 is reflected on the reference surface 60 by the first reflecting element 30a forming on the reference surface a first image I and then from the second reflecting element 30b forming a second image I '.

In the embodiment in which the laser emitter 50 is configured to emit a plurality of laser beams, a first laser beam is emitted so that it is reflected by the first reflecting element 30a and affects the reference surface 60 at a point b1 and a second laser beam which is reflected by the second reflecting element 30b going to affect the reference surface 60 at the second point c1.

In all these embodiments, the two points c1, b1 of incidence of the laser beams 51 'reflected by the two reflecting elements 30a, 30b are detected, i.e. the coordinates of the geometric center of the images I, I' reflected on the reference surface 60 .

In the embodiments in which the reflecting elements 30a, 30b have a reflecting surface with a reflective section that is not constant along the vertical axis, the width dii, d21 of the two images I, I 'reflected on the reference surfaces is preferably also measured.

In the embodiments in which a distance detection device is also present, the distance of the two reflecting elements 30a, 30b from the reference surface 60 is also measured.

The vehicle is then moved along its axis of advancement v, preferably by activating the driving wheels, up to a second position.

In practice, as illustrated in Figures 3a and 3b, the vehicle a is made to advance by an appropriate distance, bringing it closer to the calibration device 20 and to the reference surface 60.

With the vehicle stationary in the second position, the same operations already performed with the vehicle a in the first position are carried out and the two points b2, c2 of incidence of the laser beam 51 'reflected on the reference surface 60 are then detected, possibly the two distances of the reflecting elements 30a, 30b from the reference surface 60 and possibly the width dl2, d22 of the two images of the laser beam 51 "reflected on the reference surface 60.

In practice, by detecting the two points of incidence b1, c1, b2, c2 of the laser beam 51 * reflected on the reference surface 60, it is intended to determine the coordinates Xb1, Yb1, Xc1, Yc1, Xb2, Yb2, Xc2, Yc2 of such points b1, c1, b2, c2 on the plane constituted by the reference surface 60, with respect to a predetermined reference system.

For example, in the embodiment in which the trajectory detection unit 62 is constituted by a computer system and in which the reference surface 60 is constituted by a screen comprising a dense array of optical sensors, the coordinates Xb1, Yb1, Xc1, Yc1, Xb2, Yb2, Xc2, Yc2 of each point of incidence b1, c1, b2, c2 of the laser beam 51 'reflected on the reference surface 60 are determined by the computer system which constitutes the trajectory detection unit 62 in based on the electrical signals produced by the sensors hit by the reflected laser beam 51 '.

In the case in which the reflected laser beam 51 'produces a non-pointlike image I on the reference surface 60, the computer system calculates the geometric center of the image I by identifying the coordinates of this geometric center as the coordinates of the point of incidence (see figures 3c and 4c).

In some embodiments one or more optical elements are provided, such as lenses, which focus the laser beam 51 'reflected on the reference surface 60 in such a way that the image I produced is point-like.

In this way the coordinates Xb1, Yb1, Xc1, Yc1, Xb2, Yb2, Xc2, Yc2 are determined on the geometric plane on which the reference surface 60 lies.

The coordinates of the four points of incidence b1, c1, b2, c2 are then processed by the trajectory detection unit 62 (preferably by means of a suitable software) to determine the orientation of the advancement axis v of the vehicle a and therefore the misalignment w of the same with respect to the calibration device 20, through the well-known laws of geometry in space and of trigonometry.

For example, in one of the possible embodiments, the software included in the trajectory detection unit 62 solves the SI system of 8 equations in 8 unknowns:

where Xb1, Yb1, Xc1, Yc1, are the coordinates of the two points b1, c1 of incidence of the reflected laser 51 "on the reference surface 60 with the vehicle in the first position, known as measured as previously explained; Xb2, Yb2, Xc2, Yc2 are the coordinates of the two points b2, c2 of incidence of the reflected laser 51 'on the reference surface 60, with the vehicle in the second position, known as measured as previously explained; X'b1, X'c1, Z 'b1, Z'c1 and Y'bc are the coordinates of the points of intersection of the laser beam 51 with the first and second reflecting elements with the vehicle in the first position; fx and fy are parameters that depend on the orientation of the laser 50 and k and k1 are parameters that represent the orientation of the advancement axis v of the vehicle a (and more precisely they represent the coefficients of the parametric line x = k * t, y * k1 * t which represents the movement of the car from the first position to the second position ).

Therefore, calculating k and k1 is equivalent to calculating the misalignment w of the vehicle's travel axis v, since the angle w that the vehicle's travel axis v forms with the normal to the reference surface can be expressed as a function of k and k1 (W can be expressed for example as arctg (k / k1)).

Optionally, in the embodiments in which the reflecting elements 30a, 30b have a conical or frusto-conical shape (or in any case have a curved reflecting surface with an increasing or decreasing radius of curvature along the vertical axis), the trajectory 62 also measures the width d11, d21, d12, d22 along the horizontal axis X of the four images I (two with the vehicle in the first position and two with the vehicle in the second position) that the laser beam 51 'reflected by the two elements reflectors 30a, 30b form on the reference surface 60.

Again in this embodiment, the misalignment w of the advancement axis v of the vehicle a with respect to the calibration device 20 is determined, by the trajectory detection unit 62, also as a function of the four measured widths d11, d12, d21, d22 , thus obtaining a more accurate measurement of the misalignment which also takes into account any misalignment w 'with respect to the ideal horizontal plane 101 due to an imperfect flatness of the horizontal surface 102 on which the vehicle a rests.

In practice, the detection unit of the trajectory 62, in addition to those of the geometric center, also determines the coordinates of the two lateral boundary points of each image I (i.e. of the two illuminated points of the image farthest from the geometric center and lying on the same horizontal line of the geometric point itself).

More in detail, in an embodiment in which the reflecting element 30a, 30b has a conical shape and therefore the curvature of the reflecting surface grows linearly along the vertical axis, the width of the image I formed by the laser beam 51 'reflected on the surface of reference 60 is directly proportional to the height at which the laser beam 51 strikes the reflecting surface.

In this embodiment, four equations of the type d = y * z * C (where d is the width of the image formed by the laser beam 51 'reflected on the reference surface 60, y is the coordinate along the vertical axis Y (i.e. the height) of the point of incidence of the laser beam 51 on the reflecting element, z is the coordinate along the Z axis (i.e. the distance from the reference surface 60) of the same point of incidence and C is a numerical parameter that takes into account the inclination of the laser beam 51 and the shape of the reflecting element 30a, 30b. The software included in the trajectory detection unit 62 can therefore, for example, solve the S2 system of 12 equations in 12 unknowns:

d22 = Y2 * Z'c2 * C2

thus also obtaining Y1 and Y2 which represent the height (with respect to the ideal horizontal plane 101) at which the reflecting elements 30a, 30b are located with the vehicle a in the first and second position respectively. The misalignment w 'with respect to the ideal horizontal plane is therefore also determined from the two heights Y1 and y2 (for example, by expressing w' in terms of angle, w '= arctg ((Zb2-Zb1) / (Y2-Y1)) or by other equivalent calculations.

In other embodiments, the software included in the path detection unit 62 is programmed to perform other substantially equivalent calculations.

In the embodiments in which a distance detection device is also present and in which the distances of the reflecting elements 30a, 30b from the reference surface 60 with the vehicle a in the first and second position are measured, the trajectory detection unit 62 determines the misalignment w of the advancement axis v of the vehicle a with respect to the calibration device 20 as a function also of the measured distances Zb1, Zb2. In practice, in a possible embodiment, the software included in the trajectory detection unit 62 calculates the misalignment w of the advancement axis v of the vehicle a with respect to the calibration device 20, for example by solving the equation

w = arctg ((Xb2-Xb1) / (Zb1-Zb2))

where Xb2 and Xb2 are the coordinates along the X axis of the points of incidence of the laser beam 51 on a reflecting element 30a with the vehicle a respectively in the first and second position and Zb1 and Zb2 are the distances of the same reflecting element 30a from the surface reference 60 with the vehicle in the first and second positions respectively. The coordinates are always detected as a function of the point of incidence b1, b2 on the reference surface 60 of the laser beam 51 'reflected by the reflecting element, according to the method illustrated above, or by translating the laser emitter 50 along the X axis, or by other known technique.

In this last embodiment described it is possible to use only one reflecting element 30a.

Once the misalignment of w, w 'of the advancement axis of the vehicle a with respect to the calibration device 20 has been determined, the electromagnetic driving aid device is then calibrated by means of the calibration device 20, compensating for the misalignment w as already explained. .

Ultimately, the invention allows, in all its embodiments, to determine very precisely the misalignment w, w 'of the advancement axis v of the vehicle a with respect to the calibration device 20 starting from the detection of the points b1 , b2, c1, c2 of incidence of the laser beam 51 'reflected by the reflecting elements 30a, 30b on the reference surface 60, repeating this detection with the vehicle in two different positions along the real axis of advancement, thus allowing a calibration of the devices electromagnetic guides to aid more precise and at the same time faster and simpler than the prior art.

In practice it has been found that the apparatus and the method for the calibration of electromagnetic driving aid devices, according to the present invention, accomplish the intended aim and objects in this glove allow to obtain a precise alignment to the axis of advancement of a vehicle of a calibration device for electromagnetic driving aids.

Another advantage of the method and of the apparatus according to the invention consists in obtaining greater precision and simplifying the measurements.

Another advantage of the method and of the apparatus according to the invention consists in giving the greatest guarantees of reliability and safety in use.

A further advantage of the method and of the apparatus according to the invention consists in the fact that it is easy to produce and economically competitive if compared to the known art.

The apparatus and method for calibrating electromagnetic devices for driving a vehicle thus conceived are susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept.

Furthermore, all the details can be replaced by other technically equivalent elements.

In practice, the materials employed, so long as they are compatible with the specific use, as well as the contingent shapes and dimensions, may be any according to requirements.

Claims (14)

1. Method for the calibration of electromagnetic driving aids of a vehicle (a) which includes at least the steps of: - a) coupling at least one reflective element (30a, 30b) to the vehicle bodywork (a); - b) emitting from a laser emitter (50) at least one laser beam (51) in the direction of the at least one reflecting element (30a, 30b), with the vehicle (a) in a first position; - c) detect at least one point (bl, cl) of incidence on a reference surface (60), integral with a calibration device (20), of the laser beam (51) reflected by the at least one reflecting element (30a, 30b ) with the vehicle (a) in the first position; - d) advance the vehicle (a) along its axis of advancement (v) to a second position; e) emitting from the laser emitter (50) at least one laser beam (51) in the direction of the at least one reflecting element (30a, 30b); - f) detect at least one point (b2, c2) of incidence on the reference surface (60), of the laser beam (51 ') reflected by the at least one reflecting element (30a) with the vehicle (a) in the second position; - g) determine the misalignment (w) of the advancement axis (v) of the vehicle (a) with respect to the calibration device (20) as a function of at least the points (b1, b2, c1, c2) detected at step c and step g; - h) perform the calibration of the electromagnetic driving aid device by means of the calibration device (20) by compensating for the misalignment (w) of the advancement axis (v) of the vehicle (a) with respect to the calibration device (20). 2. Method according to claim 1 characterized by the fact that in step a) at least one first (30a) and a second (30b) reflecting element (30a, 30b) are coupled to the vehicle bodywork (a) and by the fact that in each of the steps c) and f) at least a first (b1, c1) and a second (b2, c2) point of incidence of the laser beam 51 'reflected by said first (30a) and said second (30b) reflecting element respectively; step g) including at least the step of: - determine the misalignment (w) of the advancement axis (v) of the vehicle (a) with respect to the calibration device (20) as a function of the coordinates (Xb1, Yb1, Xc1, Xc2) of the at least four points (b1, c1, b2, c2) detected in step c) and step f). 3. Method according to claim 2, characterized in that in step a) reflective elements are coupled to the vehicle bodywork (a) comprising a reflecting surface with variable geometry along the vertical axis, from the fact that in steps b) and e) a laser beam (51) consisting of a horizontal laser line or a horizontal laser scan is emitted and from the fact that each of steps c) and f) includes the step of: - measuring the width (d11, d21) along the horizontal axis (X) of the images (60) produced on the reference surface (60) by the laser beam reflected (51 ') from the reflecting elements (30a, 30b); in step g) the misalignment (w) of the advancement axis (v) of the vehicle (a) with respect to the calibration device (20) being determined also as a function of the widths (d11, d21, d12, d22) measured at points c ) and f) in such a way as to also determine the misalignment with respect to the horizontal plane (W). 4. Method according to one or more of the preceding claims, characterized in that between step c) and step d) it comprises the further step of: - c1) measuring the distance between at least one reflecting element (30a, 30b) and the reference surface (60), with the vehicle (a) in the first position; and between step f) and step g) includes the further step of: gl) measuring the distance between at least one reflective element (30a, 30b) and the reference surface (60) with the vehicle (a) in the second position; in step g) the misalignment (w, w ') of the advancement axis (v) of the vehicle (a) with respect to the calibration device (20) being determined also as a function of the distances measured at points c1) and g1). 5. Method according to one or more of the preceding claims characterized in that step h) comprises at least one of the following steps: - 11) correcting the readings made by the calibration device (20) according to the misalignment (w, w ') of the vehicle advancement axis (v) (a) with respect to the calibration device (20); - 12) change the orientation of the calibration device (20) with respect to the vehicle (a) in such a way that the misalignment (w, w ') of the axis of advancement (v) of the vehicle (a) with respect to the calibration device (20) is null. Apparatus (10) for carrying out a method according to one or more of the preceding claims, comprising a calibration device (20) for one or more driving aid devices, characterized in that it further comprises: - a laser emitter (50); - at least one reflecting element (30a, 30b) for the reflection of at least one laser beam (51) emitted by the laser emitter (50) configured to be coupled to the bodywork of a vehicle (a); - an alignment device (61) which comprises a reference surface (60) on which the laser beam reflected (51 ') from the reflecting elements (30a, 30b) affects, said alignment device (61) being configured to detect the misalignment (w, w ') of the calibration device (20) from the axis (v) of advancement of the vehicle (a) at least as a function of the points (b1, c1) of incidence on the reference surface (60) of the laser beam (51 ') reflected by the reflecting elements (30a, 30b) with the vehicle (a) first in a first position and then in a second position reached by translating the vehicle (a) along the forward axis (v). 7. Apparatus (10) according to claim 6, characterized in that at least the alignment device (61) and the calibration device (20) are mutually integral and configured to translate along two axes (x, y) perpendicular to each other . Apparatus (10) according to claim 6 or 7, characterized in that it comprises at least two of said reflective elements (30a, 30b) and in that the alignment device (61) is configured to detect the misalignment (w, w ') of the calibration device (20) from the axis of advancement (v) of the vehicle (a) at least as a function of the two points (bl, cl) of incidence on the reference surface (60) of the reflected laser beam (51') by the two reflecting elements (30a, 30b) with the vehicle (a) in said first position and by the two points (b2, c2) of incidence on the reference surface (60) of the laser beam (51 ') reflected by the two reflecting elements ( 30a, 30b) with the vehicle (a) in said second position. Apparatus (10) according to one or more of claims 6 to 8, characterized in that the alignment device (61) further comprises: - at least one optical sensor configured for the detection of points (b1, c1, b2, c2) of incidence of the laser beam (51 ') on the reference surface (60); - a unit for detecting the trajectory (62) configured to determine the misalignment (w, w ') of the calibration device (20) from the axis (v) of advancement of the vehicle (a) as a function of at least the coordinates of the points (b1 , c1, b2, c2) of incidence of the reflected laser beam (51 ') on the reference surface (60) detected by the optical sensor. Apparatus (10) according to one or more of claims 6 to 9, characterized in that the laser emitter (50) is configured to emit a horizontal laser line or a horizontal laser scan. 11. Apparatus (10) according to one or more of claims 8 to 10, characterized in that the reflecting elements (30a, 30b) comprise at least one reflecting surface with a reflective section that is not constant along the vertical axis, so that a laser beam incident is reflected with different divergences or widths when it cuts at different heights, and the alignment device is configured to determine the misalignment (w, w ') also as a function of the width along the horizontal axis of the two images (I) on the surface of reference (60) of the laser beam reflected (51 ') by the two reflecting elements (30a, 30b). Apparatus (10) according to one or more of claims 6 to 11, characterized in that the alignment device (61) comprises a distance measuring device configured to measure the distance between the reference surface (60) and the reflective elements (30a, 30b). Apparatus (10) according to one or more of claims 6 to 12, characterized in that: - when the electromagnetic driving aid is a vehicle headlight, the calibration device (20) is a tool for checking the alignment of the headlights, - when the electromagnetic driving aid device is an obstacle detection device, the calibration device (20) is an instrument for measuring the alignment of obstacle detection devices, - when the electromagnetic driving aid device is an optical data acquisition device, the calibration device (20) is an instrument for measuring the alignment of optical data acquisition devices. Apparatus (10) according to claims 9 and 13, when the electromagnetic driving aid device is a vehicle headlight, characterized in that the calibration device (20) comprises a camera for detecting the light emitted by the headlights comprising an optical sensor; said optical sensor being the optical sensor configured for detecting the points (b1, c1) of incidence of the laser beam (51 ') on the reference surface (60); said reference surface (60) being coplanar to, or coinciding with, said optical sensor.