WO2011150946A1

WO2011150946A1 - Method of determining an arrangement of a portable communication device within a coordinate system of a vehicle, corresponding computing unit and portable communication device

Info

Publication number: WO2011150946A1
Application number: PCT/EP2010/003322
Authority: WO
Inventors: Siav Kuong Kuoch; Patrick Bonhoure
Original assignee: Valeo Schalter Und Sensoren Gmbh
Priority date: 2010-06-01
Filing date: 2010-06-01
Publication date: 2011-12-08
Also published as: EP2577227A1

Abstract

There is provided a method for determining an arrangement (x_s,y_s, z_s, β, γ, λ) of a portable communication device (11) - like smart phone - within a coordinate system (x, y, z) of a vehicle, the portable communication device (11) being configured to support a driver in driving the vehicle. The arrangement (x_s,y_s, z_s, β, γ, λ)of the portable communication device (11) within the coordinate system (x, y, z) of the vehicle is determined by a computing unit on the basis of sensor data obtained by at least one sensor.

Description

Valeo Schalter und Sensoren GmbH

METHOD OF DETERMINING AN ARRANGEMENT OF A PORTABLE COMMUNICATION DEVICE WITHIN A COORDINATE SYSTEM OF A VEHICLE, CORRESPONDING COMPUTING UNIT AND PORTABLE

COMMUNICATION DEVICE

The invention relates to a method for determining an arrangement of a portable communication device within a coordinate system defined for a vehicle. The portable communication device is configured for supporting the driver in driving the vehicle; for instance, an application is running on the portable communication device that supports the driver during the driving task. The invention also relates to a computing unit for performing such method as well as a portable communication device that comprises such computing unit.

It is prior art that portable communication devices - such as for instance mobile telephones (smart phones) or mobile personal computers (personal digital assistants, for example) - are used for driver support in vehicles. For instance a portable communication device can be employed for recognition of road markings and it can warn the driver if the vehicle leaves the lane. For this purpose, a camera of the portable communication device is used that records an image of the region in front of the vehicle; a computing unit of the portable communication device then processes the recorded image. The computing unit then determines the position of the vehicle relative to the recognized road markings, namely on the basis of the results rendered by the image processing.

An object of the present invention is to provide a solution as to how the reliability of a portable communication device when supporting the driver in driving the vehicle can be improved over the prior art.

This problem is solved - according to the invention - by means of a method having the features of patent claim 1 and by a computing unit having the features according to patent claim 17 as well as by a portable communication device having the features according to patent claim 18. Advantageous embodiments of the invention are subject matter of the dependent patent claims and the description. An inventive method serves for determining the arrangement of a portable communication device within a coordinate system defined for a vehicle. The portable communication device supports the driver in driving the vehicle. The arrangement of the portable communication device within the coordinate system of the vehicle is determined by a computing unit on the basis of sensor data obtained by at least one sensor.

This means that according to the invention the arrangement of the portable

communication device within the coordinate system of the vehicle is determined by a computing unit in dependence of sensor data recorded by means of a sensor. This increases reliability of the portable communication device when supporting the driver in driving the vehicle; the current arrangement of the portable communication device within the coordinate system of the vehicle at each moment namely is always known. The invention is based on the insight that a reliable provision of functions for driver support is not always ensured in the prior art, and this because the portable communication device does not know its own arrangement within the vehicle. In the prior art it therefore is not possible to determine the exact position of the vehicle relative to the road markings, for example. This very problem is addressed by the invention: The arrangement of the portable communication device within the coordinate system of the vehicle is determined, namely on the basis of sensor data. The portable communication device thus knows its current arrangement within the vehicle and thus is capable of determining with high accuracy for example the relative position of the vehicle with regard to a road marking. The arrangement of the portable communication device within the coordinate system of the vehicle can be determined very accurately on the basis of sensor data provided by a sensor.

The portable communication device is a retrofit part that is retrofitted in the vehicle for driver support. This may be for instance a mobile phone (smart phone) or a mobile personal computer, like personal digital assistant, organizer or the like. Such devices nowadays have a high computing power and thus can be employed for driver assistance. The portable communication device thus is not a factory-fitted component of a driver assistance system.

The term ..arrangement"- according to the present invention - comprises an absolute position within the coordinate system of the vehicle - this position can be unambiguously defined by coordinate values - and/or an orientation or alignment within the coordinate system of the vehicle - this in turn can be defined by a roll angle and/or a pitch angle and/or a yaw angle. The coordinate system defined for the vehicle preferably is a Cartesian coordinate system. The origin of the coordinate system can be defined to be located at any random point of the vehicle, namely for instance in a middle point of a rear axis or a middle point of a bottom edge of the windscreen.

Preferably sensor data are employed for determining the arrangement, the data being obtained exclusively by at least one internal sensor of the portable communication device. Then, the computing unit determines the arrangement on the basis of sensor data of at least one sensor of the portable communication device, and no further devices or external sensors need to be employed. Then, the method does not require additional external sensors. In an alternative embodiment, it may be provided that the arrangement is determined on the basis of sensor data of an external sensor that is separate from the portable communication device, namely for instance a separate camera.

For determining of the arrangement principally sensor data of the most varied sensors may be employed. For instance, the arrangement of the portable communication device within the coordinate system of the vehicle may be determined on the basis of an image provided by a camera - in particular of an internal camera of the portable communication device - and/or on the basis of measuring values provided by an acceleration sensor - in particular of an internal acceleration sensor of the portable communication device - and/or on the basis of measuring values provided by a compass - in particular by an internal compass of the portable communication device. All these sensors facilitate determination of the arrangement of the portable communication device within the coordinate system of the vehicle with a high accuracy and at a low effort.

With regard to the place of the determination of the arrangement, it means with regard to the location of the computing unit in principle there are two embodiments provided: The computing unit may be an internal computing unit of the portable communication device; in this case the arrangement is determined by an internal computing unit of the portable communication device. Alternatively, the sensor data can be transmitted to an external, namely a remote host server; in this case the arrangement of the portable communication device can be calculated by a powerful computing unit of the host server, and data containing information about the arrangement can be transmitted by the host server to the portable communication device. As already set out, the determining of the arrangement may comprise determining an absolute position of the portable communication device within the coordinate system of the vehicle. In this case the actual position of the portable communication device in space is known, so that the portable communication device can reliably support the driver in driving the vehicle. In particular, errors in determining the relative position of the vehicle with regard to a road marking are avoided, and a false alarm rate when warning the driver about the vehicle leaving the lane can be reduced to a minimum.

For determining the absolute position of the portable communication device within the coordinate system of the vehicle preferably at least two coordinate values, in particular three coordinate values, are calculated. If the coordinate system is a Cartesian one, preferably all three coordinate values are calculated, so that the position of the portable communication device in three-dimensional space is known. In an alternative embodiment in the case of a Cartesian coordinate system equally as well only two coordinate values can be calculated, namely in particular in the transverse direction of the vehicle and in the vertical direction of the vehicle. This is due to the fact that portable communication devices as a rule are attached to a windscreen so that the position of the portable communication device in the longitudinal direction of the vehicle is largely known.

The determination of the absolute position of the portable communication device in the coordinate system may be effected in such a way that the position of the portable communication device itself is determined. It may, however, also be envisaged that the determination of the position of the portable communication device is indirectly effected by determining an absolute position of a holding device within the coordinate system. This means the position of the holding device - on which the portable communication device is mounted - may be determined; this position then corresponds to the position of the portable communication device, if same communication device is mounted on the holding device.

In one embodiment, from each of at least two reference points of the vehicle a distance of the portable communication device or a holding device is determined on the basis of the sensor data, and the absolute position then is calculated from the at least two distances. This means that the determination of distances of the portable communication device or its holding device from at least two reference points of the vehicle - the position of the reference points within the coordinate system of the vehicle is basically known - facilitates an exact determination of the position of the portable communication device (or the holding device) within the coordinate system of the vehicle. This is a very robust and reliable method.

With regard to the determination of the distances of the portable communication device or the holding device from at least two reference points of the vehicle the most varied embodiments are envisaged:

At least two - in particular at least three - marking elements having a predetermined pattern can be provided that can be mounted at a predetermined place of the vehicle. The marking elements may for instance be adhesive tags or stickers and/or so-called suction cup or sucking disc elements that can be attached to the windscreen or the dashboard of the vehicle at little effort. This means that the user can attach each of the at least two marking elements to a predetermined place in the vehicle, namely preferably to the windscreen. Then, an image can be recorded by a camera, the image containing all marking elements. The user will preferably record an image in which the complete wind screen including the marking elements attached thereto is shown. The computing unit then detects the marking elements in the image and defines the at least two reference points in the image in dependence on the position of the marking elements. The actual distances (in space) between the portable communication device or its holding device and the reference points within the coordinate system of the vehicle then are calculated from the distances in the image.

The named image may be recorded either by a camera of the portable communication device itself or by a separate random camera. The computing unit processes the image, recognizes the attached marking elements, determines the at least two reference points in dependence on the positions of the marking elements in the image, calculates the distances between the portable communication device (or the holding device) and the reference points in the image (in pixels) and subsequently calculates the actual distances within the coordinate system of the vehicle (in meters). For this calculation, the computing unit can also use further information, namely vehicle-specific information, such as for instance the actual dimensions of the windscreen and/or the coordinate values of at least one point of the windscreen within the coordinate system of the vehicle and/or the orientation angle of the windscreen within the coordinate system.

Also for the portable communication device and/or for the holding device a marking element may be provided, namely one with a predetermined pattern. Thus the computing unit can detect the portable communication device or the holding device in the recorded image and calculate the corresponding distances at little computing effort.

The above-described embodiment for instance can be realized in the following sequence: The driver places three marking elements on the windscreen, namely a first marking element at a middle point of the top edge of the windscreen, a second marking element at a middle point of the bottom edge of the windscreen, and a third marking element in a top corner of the windscreen, e.g. on the driver's side of the vehicle. On the windscreen moreover is attached a holding device for a portable communication device - namely for a mobile telephone. Also this holding device contains a marking element. All marking elements - for instance adhesive labels or sucking discs - have a predetermined pattern, for instance a circle, a ring, a cross or a similar pattern. The driver records an image of the complete windscreen, namely with the aid of his portable communication device that is equipped with a camera. An internal computing unit of the portable communication device receives this image and processes it. By means of a special algorithm - for instance the Hough Transformation - the computing unit detects the predetermined pattern of the marking elements in the image. This means, the computing unit detects the marking elements in the image. The computing unit calculates - in pixels - the distance between the first marking element (centre point of the top edge) and the second marking element (centre point of the bottom edge) as well as the distance between the first marking element and the third marking element (top corner above the driver). The distance between the first and the second marking element corresponds to the width of the windscreen in pixels, whilst the distance between the first and the third marking element corresponds to half the length of the windscreen in pixels. Then, the computing unit determines two reference points, namely a first reference point that is located on a connection line between the first and the second marking element, as well as a second reference point that is located on a connection line between the first and the third marking element. The reference points are determined with the aid of a corresponding algorithm, namely in particular the so-called AdaBoost algorithm. Thus, the first reference point is the one on the connection line between the first and the second marking element through which runs a line extending through the marking element of the holding device and perpendicularly to said connection line. Correspondingly, the second reference point is the point on the connection line between the first and the third marking element through which runs a line extending through the marking element of the holding device that is perpendicular to the connection line between the first and the third marking element. Consequently, the distance between the marking element of the holding device and the first reference point corresponds to the distance between the marking element of the holding device and a middle axis of symmetry of the windscreen, whilst the distance between the marking element of the holding device and the second reference point corresponds to the distance of the marking element of the holding device and the top edge of the windscreen. In this process the computing unit calculates the two distances in pixels. The computing unit moreover receives a piece of information about the model or the type series as well as about the manufacture year of the vehicle; these pieces of information are entered by the driver into the portable communication device. These pieces of information may also be stored in the portable communication device. From these pieces of information - for instance from the internet or a proprietary database - the computing unit gathers the dimensions of the windscreen as well as the coordinate values of at least one point of the windscreen within the coordinate system of the vehicle and an orientation angle of the windscreen relative to said coordinate system. The distances of the marking element of the holding device from the two reference points in pixels are now converted in corresponding actually distances in space (in meters, for example), namely in dependence on the dimensions of the windscreen. Subsequently in dependence of the coordinate values of the windscreen, the calculated distances and the orientation angle of the windscreen the coordinate values of the marking element of the holding device within the coordinate system of the vehicle are calculated. Through these coordinate values the absolute position of the marking element of the holding device and thus also the portable communication device within the coordinate system of the vehicle is unambiguously known. These coordinates are then used by the portable communication device for supporting the driver in driving the vehicle.

The above-described method has the advantage that the absolute position of the portable communication device can be determined at little effort, namely by way of recording merely an image as well as with the aid of four marking elements. This determination of the position is very accurate, so that the portable communication device can

correspondingly provide reliable support to the driver of the vehicle.

As has already been set out, also for the portable communication device and/or for the holding device a marking element can be provided, then the computing unit can also detect the holding device or the portable communication device (if an external camera is used) in the recorded image at little expense and calculate the above-named distances.

In an alternative embodiment, the at least two distances - between the at least two reference points and the portable communication device or the holding device - can be determined from measuring values provided by an acceleration sensor. This acceleration sensor is preferably an internal sensor of the portable communication device. For obtaining the measuring values the portable communication device is moved between a holding device (located for instance on the windscreen) and the first reference point as well as between the holding device and a second reference point. The computing unit can then calculate the distances between the holding device and the two reference points of the vehicle on the basis of the measuring values provided by the acceleration sensor - namely by way of integration. In this embodiment, no further marking elements are required, and the absolute position of the holding device within the coordinate system of the vehicle can still be determined with a high degree of accuracy. This embodiment for instance can be realized in the following sequence: On the windscreen of the vehicle a holding device for a portable communication device - namely a mobile phone - is attached. The portable communication device has an acceleration sensor for measuring the acceleration. A computing unit of the portable communication device receives the measuring values provided by the acceleration sensor and processes them. The driver takes the portable communication device and holds it in such a way that it touches the holding device sideways, for instance on the right side. The driver subsequently moves the portable communication device horizontally from the holding device up to a right edge of the windscreen until the portable communication device touches the lateral wall. The portable communication device bumps slightly against the lateral wall. The driver then moves the portable communication device equally horizontally back towards the holding device, namely until the portable communication device has reached the holding device again. Thereafter the driver performs the same act in the vertical direction; he moves the portable communication device from the holding device along the windscreen upwards until the portable communication device touches the roof lining slightly. The driver then moves the portable communication device back to the holding device. During these motion procedures the acceleration sensor measures the acceleration of the portable communication device, and the computing unit receives the measuring values. The computing unit integrates the measuring values twice and thus calculates two distances on the whole, namely the distance between the holding device and the side edge (first reference point) as well as the distance between the holding device and the top edge of the windscreen (second reference point). The computing unit also knows - as has been set out in the above - the coordinate values of at least one point of the windscreen within the coordinate system of the vehicle, as well as the orientation angle of the windscreen. From these pieces of information as well as from the calculated distances the computing unit calculates the coordinate values of the holding device within the coordinate system of the vehicle. So, in one embodiment, the two distances are determined within a plane of a windscreen of the vehicle. Thus, it is possible to determine the absolute position of the portable communication device or the holding device on the basis of merely two reference points or the distances between the portable communication device or the holding device and two reference points.

The determination of the arrangement may also comprise that an orientation of the portable communication device within the coordinate system of the vehicle is determined on the basis of the sensor data. This orientation is preferably determined on the basis of such sensor data that are exclusively obtained through at least one internal sensor of the portable communication device. The determination of the orientation of the portable communication device with regard to the coordinate system of the vehicle has the advantage that errors occurring in the provision of functions for driver support can be eliminated that are caused by an tilted orientation of the portable communication device in the prior art. This, too, proves particularly advantageous for such applications, in which the road markings are detected through the portable communication device - namely with the aid of a camera - and the driver is warned when leaving the lane. The false alarm rate can thus be reduced to a minimum.

What is particularly advantageous is to determine a roll angle and/or a pitch angle and/or a yaw angle of the portable communication device within the coordinate system of the vehicle for the determination of the orientation. For determining these angles a local coordinate system is defined for the portable communication device, and the

corresponding angles are determined on the basis of the orientation of the local coordinate system in relation to the coordinate system of the vehicle.

The roll angle and/or the pitch angle is/are preferably determined solely on the basis of the measuring values provided by an acceleration sensor of the portable communication device. Such acceleration sensor (also G-sensor) namely preferably provides measuring values of acceleration in all three directions of the local coordinate system, so that it is possible to calculate the roll angle as well as the pitch angle on the basis of these measuring values. In this embodiment, the portable communication device can do without additional sensors when calculating the roll angle and/or the pitch angle; just one acceleration sensor suffices in order to determine the roll angle and/or the pitch angle.

The yaw angle, by contrast, describes the extent of the rotation of the portable

communication device about the vehicle's vertical axis, and it is not possible to determine the yaw angle merely on the basis of measuring values provided by the acceleration sensor whilst the vehicle is at a standstill. However, this succeeds, when the vehicle is driven straight on for a certain period of time. The driver consequently is encouraged by the communication device to drive the vehicle on a straight stretch for a certain period of time - e.g. for five seconds. The computing unit then receives measuring values provided by the acceleration sensor that are recorded during this motion and subsequently calculates the yaw angle. The computing unit also ensures that the vehicle was driven straight on. This is preferably determined on the basis of measuring values provided by a compass of the portable communication device. Whilst the vehicle is driven, the computing unit also receives the measuring values of the compass and checks whether a predetermined calculation criterion is fulfilled or not. This criterion includes the condition that the standard deviation of a certain predetermined number of measuring values of the compass or the standard deviation of the measuring values over a predetermined period of time remains below a predetermined limit value. If this calculation criterion is fulfilled, the computing unit determines that the vehicle essentially was driven straight on, and the computing unit assesses the yaw angle as correctly determined.

According to the invention, there is provided a computing unit that is configured for performing a method according to the invention. A portable communication device according to the invention comprises a computing unit according to the invention. The embodiments presented as preferable with regard to the method according to the invention and their advantages apply in analogy to the communication device according to the invention and the computing unit according to the invention.

Further features of the invention may be gathered from the claims, the figures and the description of the figures. The features and feature combinations previously mentioned in the description as well as the features and feature combinations mentioned further along in the description of the figures and/or shown in the figures alone are usable not only in the respectively indicated combination, but also in other combinations and alone without departing from the scope of the invention.

The invention now is set out in more detail on the basis of individual embodiments as well as by making reference to the enclosed drawings.

These show in: each a schematic view of a marking element for employment in a method according to an embodiment of the invention; an image recorded with the aid of a camera, the image showing a windscreen of a vehicle with marking elements attached thereto, wherein a method according to an embodiment of the invention is explained in more detail; a schematic side view of the windscreen, wherein the calculation of the coordinate values of a holding device of a portable communication device within the coordinate system of the vehicle is explained in more detail; a schematic representation of the windscreen of the vehicle with a holding device for a portable communication device attached thereto, wherein a method according to a further embodiment of the invention is explained in more detail; a graph of an acceleration over time measured by means of an acceleration sensor of the portable communication device, a graph of a velocity calculated on the basis of the acceleration, and a graph of a distance calculated from the velocity; a graph of the distance over time, wherein a method according to a further embodiment of the invention is explained in more detail; a Cartesian coordinate system of the vehicle, wherein the terms "roll angle", "pitch angle", and "yaw angle" are explained in more detail; a schematic representation of the windscreen with the portable communication device held against it, wherein the determination of an orientation of the portable communication device within the coordinate system of the vehicle being explained in more detail; and

Fig. 11 time-dependent graphs of measuring values of a compass (left) as well as time-dependent graphs of the yaw angle, each for a first (top) and a second (bottom) driving situation, wherein a calculation criterion for the determination of the yaw angle is explained in more detail.

In the present case what is of interest is the determination of an arrangement of a portable communication device within a coordinate system of a vehicle, such as in particular a passenger car. Nowadays portable communication devices are increasingly frequently employed for supporting the driver in driving the vehicle. These are in particular mobile phones or portable personal computers, such as in particular personal digital assistants. Such portable communication devices as a rule have a camera that is suited to record images about a region in front of the vehicle, whilst the portable communication device is attached to a windscreen of the vehicle, namely with the aid of a holding device. In order to be able to determine the position of the vehicle on the road with a high degree of accuracy, also the arrangement of the communication device in the vehicle should be known. The term "arrangement" in the present case comprises both the absolute position of the portable communication device within the coordinate system of the vehicle - defined by three coordinate values - as well as the orientation of the portable

communication device with regard to the coordinate system of the vehicle - defined by the roll angle, a pitch angle as well as a yaw angle.

Subsequently a first embodiment is explained in more detail which serves for the determination of the absolute position of a portable communication device within the coordinate system of the vehicle. Marking elements 1 are provided, namely for instance three or four marking elements 1. The marking elements 1 may be adhesive tags or suction cups that can be attached to a windscreen 2 of the vehicle, namely by the driver. The marking elements 1 have a predetermined pattern, so that a computing unit can detect the marking elements in an image of a camera.

In Fig. 1a a first example of a marking element 1 is shown. This marking element 1 is a circle element, for instance an adhesive tag or a suction cup. The pattern of this marking element 1 comprises an inner circle 3 with a first colour, e.g. black. Around the inner circle 3 there is an outer ring 4 that is concentric thereto and has a second colour, e.g. white or yellow. The marking element 1 can for instance have a diameter from a range of values from 1 °cm to 10°cm.

Fig. 1 b shows a second example of a marking element 1. This equally has a

predetermined pattern. In fact, this marking element 1 equally is a circular element. It is subdivided into four equal circular sectors 5a to 5d that consist of pairs of the same colour. Namely two opposite circular sectors 5a, 5c have a first colour, for instance black, whilst the remaining two circular sectors 5b, 5d have a second colour, for instance white or yellow. Also the marking element 1 according to Fig. 1 b may be an adhesive tag or a suction cup. It preferably has a diameter from a range of values from 1 cm to 10 cm.

For the determination of the absolute position of the portable communication device within the coordinate system of the vehicle the driver attaches three marking elements 1 to the windscreen 2. Namely the driver attaches - as shown in Fig. 2 - a first marking element 1a in a middle point of a top edge 6 of the windscreen 2. This is normally a foot point of the rear mirror. A second marking element 1 b is attached by the driver in a middle point of a bottom edge 7 of the windscreen 2. A third marking element 1c is attached by the driver in the top corner of the windscreen 2, for instance on the driver's side.

In Fig. 2 the windscreen 2 is shown from outside of the vehicle. A coordinate system x, y, z of the vehicle is equally shown in Fig. 2. An additional marking element 1d which may have an identical or a differing pattern than marking elements 1a to 1c is provided for a holding device of the portable communication device. This marking element 1d may be an element that is separate from the holding device or it may be integrated in the holding device; then a holding device with a particular pattern is provided. The holding device, i.e. the additional marking element 1d is mounted in that half of the windscreen 2 in which the marking element 1c is mounted, too. This means that both the holding device and the marking element 1c are mounted in the same half of the windscreen 2.

Now, the driver takes a photograph of the windscreen 2 with the marking elements 1 a to 1d attached thereto with the aid of a camera. Preferably such image of the windscreen 2 is recorded by means of the portable communication device itself, namely by means of the camera integrated therein. The driver will preferably record an image - for instance from outside of the vehicle or also from inside - that essentially comprises exclusively the complete windscreen 2, so that the windscreen 2 is shown at maximum size. The processing of the recorded image through a computing unit is then simplified.

So, an image of the windscreen 2 is preferably recorded by an internal camera of the portable communication device. The processing of the image data is equally preferably performed through an internal computing unit of the communication device. However, it is also possible that the image is recorded with the aid of any random camera, namely a camera that is separate from the portable communication device. It is also possible that the image or the image data are transmitted to a remote host server. Then the host server performs the processing of the image data and transmits data with information about the absolute position back to the portable communication device.

The processing of the recorded image is effected as follows: The computing unit receives the recorded image. The computing unit then detects the patterns of the marking elements 1a to 1d (circle detection) and thus recognizes the marking elements 1a to 1d in the image. For this purpose for instance a particular algorithm is used, namely the Hough Transformation. This means that the computing unit knows the positions of the marking elements 1 a to 1d in the image. Then the computing unit calculates a first distance d between the first marking element 1a and the second marking element 1b. This distance d is then given in pixels. This distance d corresponds to the width of the windscreen 2 in the image (pixels). The computing unit moreover calculates a second distance D, namely between the first marking element 1a and the third marking elements 1 c. The second distance D is equally given in pixels. This distance corresponds to half a length of the windscreen 2 in the image (pixels).

By means of a further algorithm - namely in particular the AdaBoost algorithm - the computing unit determines a first reference point R1 in the image which is located on a connection line between the first and the second marking elements 1a, 1 b. By means of the same algorithm the computing unit determines a second reference point R2 which is located on a connection line between the first and the third marking element 1 a, 1c. The first reference point R1 consequently is located on a middle symmetry axis of the windscreen 2, whilst the second reference point R2 is located essentially on the top edge 6 between the marking elements 1a, 1c. The first reference point R1 is chosen so that it is located on a line 8 that, on the one hand, extends through the additional marking element 1d and, on the other hand, perpendicularly to the connection line between the first and the second marking elements 1a and 1 b. Correspondingly, the second reference point R2 is chosen in such a way that it is located on a line 9 that, on the one hand, extends through the additional marking element 1d and, on the other hand and considering the curvature of the windscreen 2, approximately perpendicularly to the connection line between the first and the third marking element 1a, 1c.

The computing unit then calculates a distance r1 between the additional marking element 1d and the first reference point R1 as well as a distance r2 between the additional marking element 1d and the second reference point R2. The distance r1 corresponds to a distance of the marking element d from the middle symmetry axis of the windscreen 2 (pixels); the distance r2 corresponds to a distance of the marking element 1d from the upper edge 6 of the windscreen 2 (equally pixels).

This means that the computing unit now knows the distances r1 and r2. Equally does the computing unit know the dimensions of the windscreen 2, namely its actual length L as well as its actual width B (in meters, for example). The computing unit also knows the coordinate values of at least one point of the windscreen 2 within the coordinate system x, y, z of the vehicle. For instance the computing unit knows the coordinate values x_P, yp, z_P of a middle point P of the bottom edge 7 of the windscreen 2. Moreover, the computing unit knows an orientation angle a (see Fig. 3) of the windscreen 2; the orientation angle a is an angle between the windscreen 2 and the x axis of the coordinate system of the vehicle. All this information is received by the computing device for instance from a host server; alternatively, these pieces of information may also be stored in a storage of the portable communication device. The obtaining of this information may for instance consist in that the driver enters the model or the manufacture series of the vehicle as well as the manufacture year into the portable communication device, the computing unit sends same entry to the host server and the host server then transmits the required information to the portable communication device.

As has already been set out, the two distances r1 , r2 are given in pixels. These are then converted by the computing device into actual distances - for instance in mm, cm, or m. The conversion is performed according to the following equations: r1 (in meters, for example) = (LJ2D) ^* r1 (in pixels);

as well as

r2 (in meters, for example) = (B/d) * r2 (in pixels).

So, the computing unit now knows the actual distances r1 , r2 of the holding device of the portable communication device both from the middle symmetry axis of the windscreen 2 and from the top edge 6 of the windscreen. Depending on these actual distances r1 , r2 as well as depending on the orientation angle a and the coordinate values x_P, y_P, z_P of the middle point P of the bottom 7 the computing unit then calculates the coordinate values of the additional marking element 1d and thus of the holding device and thus of the portable communication device within the coordinate system x, y, z of the vehicle. These coordinate values are x_s, ys, Zs- From the representation according to Fig. 2 and Fig. 3 derive the following coordinate values: s = Xp - (B - r2) ^* cos(a);

y_s = y_P + r1 ;

zs = z_P + (B - r2) ^* sin(a).

Here, the distances r1 , r2 are the actual distances in space (in meters, for instance).

This means that the computing unit knows the absolute position of the portable communication device within the coordinate system x, y, z of the vehicle. It may employ these coordinate values x_s, ys, zs for the provision of the driver support functions, namely for instance for the calculation of the position of the vehicle on the road.

In the following a second example is set out in more detail which equally serves for the determination of the absolute position of the portable communication device or its holding device within the coordinate system of the vehicle. With reference to fig. 4 a holding device 10 is located on the windscreen 2. In Fig. 4 the windscreen 2 is shown from inside the vehicle. The driver takes its portable communication device 11 and moves it from the holding device 10 towards a reference point R3, namely towards the right edge 12 of the windscreen 2. In fact, the driver moves the portable communication device 11 horizontally in the direction of the arrow A1. The portable communication device 11 touches the edge 12 or the lateral wall of the vehicle slightly; then the driver moves the communication device 11 back to the holding device 10, namely in the direction of the arrow A2.

Subsequently, the driver moves the portable communication device 11 from the holding device 10 to the top - i.e. vertically - along the windscreen 2 up to the top edge 6, namely in the direction of the arrow A3. This means that the driver moves the device 11 from the holding device 10 up to a reference point R4. The device 11 slightly bumps against the top edge 6 or the roof lining; then the driver moves the portable communication device 11 back to the holding device 10, namely in the direction of the arrow A4.

The portable communication device 1 comprises an acceleration sensor which measures the acceleration of the portable communication device 11. Also whilst the communication device 11 is moving between the holding device 10 and the reference points R3, R4 the acceleration sensor records measuring values. Depending on the measuring values for the acceleration the computing unit calculates a distance between the holding device 10 and the reference point R3, on the one hand, and between the holding device 10 and the reference point R4, on the other. Fig. 5a shows a graph of the acceleration a over a time t, whilst the portable

communication device 11 is moved between the holding device 10 and one of the reference points R3, R4. At the point in time t₀ the motion of the portable communication device 11 commences and the acceleration a increases. At the point in time ti the portable communication device 11 reaches the reference point R3 or R4 and the acceleration a changes its sign - it becomes negative. At the point in time t₂ the portable communication device 11 reaches the holding device 10 again.

Fig. 5b shows a graph of a velocity V of the portable communication device 1 1 over the time t. The function of the velocity V is rendered by an integration of the funcion of the acceleration a. Fig. 5c shows a time-dependent graph of a distance w covered over the time t. This function is rendered by an integration of the graph of the velocity V.

Fig. 6 shows a graph of the path w covered over the time t whilst the portable

communication device 11 is actually moved by the driver. This means that the

development shown in Fig. 6 was generated by a double integration of the actually recorded measuring values of the acceleration. Through back and forth movements - as may be gathered from Fig. 6 - on the whole two distance values w1 , w2 may be calculated by the computing unit. The first distance value w1 corresponds to the measured distance, when the portable communication device 11 is moved from the holding device 10 to the reference point R3 or R4. The second distance value w2 corresponds to the measured distance, when the portable communication device 11 is moved back to the holding device 10. As it is not possible for the driver to move the portable communication device 1 always along the same path, two distance values w1 , w2 are now available that slightly differ from each other. The computing unit calculates a mean value from the distance values w1 , w2. This mean value then is used as actual distance between the holding device 10 and the reference point R3 or R4.

This means that the computing unit knows the two distances: the distance between the holding device 10 and the reference point R3, on the one hand, and the distance between the holding device 10 and the reference point R4, on the other hand. From these distances the computing device - in analogy to the first embodiment - calculates the coordinate values for the absolute position of the holding device 10 within the coordinate system of the vehicle. For this purpose the computing unit - as in the first embodiment - uses the information about the actual length and width of the windscreen 2 as well as about the orientation angle a of the windscreen 2 and the coordinate values x_P, y_P, z_P of the point P of the windscreen 2 within the coordinate system of the vehicle. As has already been set out, the determination of the arrangement of the portable communication device 11 within the coordinate system of the vehicle also comprises the determination of an orientation of the portable communication device 1. In this embodiment, three various angles are calculated for the determination of the orientation, namely a roll angle β, a pitch angle γ, as well as a yaw angle λ. These angles are calculated by the computing unit and used by the portable communication device 11 whilst providing support to the driver.

Fig. 7 shows a coordinate system x, y, z which is defined for the vehicle. This means it is a coordinate system of the vehicle. The yaw angle λ describes the extent of a rotation of the portable communication device 11 about the z axis of the coordinate system - as shown by arrow B1. The roll angle β describes the extent of a rotation of the portable communication device 11 about the x axis of the coordinate system, as shown by arrow B2. Finally, the pitch angle γ describes the extent of a rotation of the portable

communication device 11 about the y axis of the coordinate system of the vehicle, as shown by arrow B3.

Figs. 8 to 10 show the windscreen 2 as well as in each case two axes of the coordinate system x, y, z of the vehicle. Fig. 8 shows the vertical axis z and the transverse axis y of the vehicle, whilst Fig. 9 shows the vertical axis z and the longitudinal axis x and Fig. 10 shows the longitudinal axis x and the transverse axis y of the vehicle. Figs. 8 and 10 moreover show the portable communication device 11 that is mounted to the windscreen 2, namely with the aid of a holding device that is not shown. To the portable

communication device 11 there is defined a local coordinate system x', y', z'.

As derives from Fig. 8, the portable communication device 11 is rotated slightly about the longitudinal axis x of the vehicle. The roll angle β in this connection is an angle between the transverse axis y of the vehicle and the axis y' of the local coordinate system of the communication device 11. From Fig. 9 it derives that the portable communication device 11 is also slightly rotated about the transverse axis y of the vehicle. The pitch angle γ in this connection is an angle between the vertical axis z of the vehicle and the axis x' of the local coordinate system. With reference to Fig. 10 the yaw angle λ is an angle between the transverse axis y of the vehicle coordinate system and the axis y' of the local coordinate system of the portable communication device 11. The computing unit calculates all three angles, namely the roll angle β, the pitch angle γ and the yaw angle λ. The roll angle β and the pitch angle γ may be calculated by the computing unit whilst the vehicle is at a standstill, namely from the measuring values provided by an acceleration sensor of the portable communication device 11. The acceleration sensor namely provides measuring values for the acceleration in all three directions x', y', z' of the local coordinate system. From these measuring values for the acceleration the computing unit directly calculates roll angle β as well as the pitch angle γ.

However, the computing unit cannot calculate the yaw angle λ whilst the vehicle is at a standstill. For calculating the yaw angle λ from the measuring values of the acceleration, these measuring values need to be obtained whilst the vehicle is in motion on a straight road. So, the driver is encouraged by the portable communication device 11 to drive the car straight on, namely for a predetermined period of time, for instance for five seconds. Whilst the vehicle is driven, the acceleration sensor records measuring values. The portable communication device 11 moreover comprises a compass that equally provides measuring values during this motion. The measuring values provided by the compass give information about the global orientation of the portable communication device 11 , so that the computing unit on the basis of these measuring values can determine whether the vehicle is driven along a straight road.

This means that during this motion of the vehicle the computing unit receives both the measuring values provided by the acceleration sensor as well as the measuring values provided by the compass. From the measuring values for the acceleration the computing unit then calculates the yaw angle λ. Depending on the measuring values provided by the compass the computing unit determines whether the vehicle was driven along a straight stretch or not. The yaw angle λ is only then assessed as correctly determined if the vehicle was driven along a straight stretch. For this purpose the computing unit checks whether a predetermined calculation criterion is fulfilled or not. This calculation criterion includes the condition that the standard deviation of a predetermined number of measuring values provided by a compass remains below a predetermined value. Then it is namely ensured that the vehicle was driven along a straight stretch. If the calculation criterion is fulfilled, the computing unit assesses the calculated yaw angle λ as correctly determined. If the calculation criterion is not fulfilled, the driver is encouraged once again to drive the vehicle along a straight stretch.

Fig. 11 shows time-dependent graphs of the measuring values provided by the compass (left), i.e. development of the global orientation φ of the portable communication device 11 , as well as time-dependent graphs of the yaw angle λ (right). Fig. 1 1 illustrates the graphs for two different situations: In the case of the top graphs the calculation criterion is not fulfilled, whilst in the case of the bottom graphs the criterion is fulfilled. As can be seen from the top graphs, the standard deviation from the measuring values of the orientation φ is clearly larger than the standard deviation of the bottom graphic of the orientation φ. Also the bottom function of the yaw angle λ is clearly more stable than the top one. In fact, over a predetermined period of time during which the vehicle is driven straight on a multitude of calculated values of the yaw angle λ are available. The computing unit averages these values and takes the mean of these values; the final value for the yaw angle λ is then a mean value from a multitude of values of the yaw angle λ that are calculated during the motion of the vehicle.

Claims

Valeo Schalter und Sensoren GmbH Claims

1. A method for determining an arrangement (x_s, ys, z_s, β_» γ, λ) of a portable

communication device (11) within a coordinate system (x, y, z) of a vehicle, the portable communication device (11) being configured to support a driver in driving the vehicle, wherein the arrangement (x_s, ys, z_s, β, γ, λ) of the portable

communication device (11) within the coordinate system (x, y, z) of the vehicle is determined by a computing unit on the basis of sensor data obtained by at least one sensor.

2. A method according to claim 1 in which the arrangement (x_s, ys, z_s, β, γ, λ) is

determined on the basis of sensor data which are exclusively obtained by at least one internal sensor of the portable communication device (11).

3. A method according to claim 1 or 2 in which the arrangement (x_s, ys, z_s, β, γ, λ) is determined on the basis of an image provided by a camera and/or on the basis of measured values provided by an acceleration sensor and/or on the basis of measured values provided by a compass.

4. A method according to one of the preceding claims in which determining the

arrangement (x_s, ys, z_s, β, γ, λ) comprises determining an absolute position (x_s, ys, z_s) of the portable communication device (11) within the coordinate system (x, y, z) of the vehicle.

5. A method according to claim 4 in which for determining the absolute position (x_s, ys, z_s) at least two coordinate values (x_s, ys, z_s), in particular three coordinate values (xs, ys, z_s), of the coordinate system (x, y, z) are calculated.

6. A method according to claim 4 or 5 in which the determining of the position (x_s, y_s, z_s) of the portable communication device (11 ) within the coordinate system (x, y, z) is performed indirectly by determining the absolute position (x_s, ys, z_s) of a holding device (10) for the portable communication device (11) within the coordinate system (x. y> z).

7. A method according to one of the claims 4 to 6 in which from each of at least two reference points (R1 , R2; R3, R4) in the vehicle a distance (r1 , r2; w) of the portable communication device (11) or of a holding device (10) is determined on the basis of the sensor data and the absolute position (x_s, y_s, z_s) is calculated from the at least two distances (r1 , r2, w).

8. A method according to claim 7 in which each of at least two marking elements (1) having a predetermined pattern are provided for attachment to a predetermined place of the vehicle, wherein the marking elements (1) are recognized by the computing unit on the basis of an image provided by a camera and in dependence on a position of the marking elements (1) in the image the at least two reference points (R1 , R2) in the image are determined, and wherein the actual distances (r1 , r2) within the coordinate system (x, y, z) of the vehicle are calculated from the distances (r1 , r2) in the image.

9. A method according to claim 8 in which also for the portable communication device (11) and/or for the holding device (10) a marking element (1d) is provided.

10. A method according to claim 7 in which the at least two distances (r1 , r2, w) are determined from measured values provided by an acceleration sensor, wherein the portable communication device (11 ) is moved between the holding device (10) and a first reference point (R3) as well as between the holding device (10) and the second reference point (R4) for obtaining the measured values.

11. A method according to one of the claims 7 to 10 in which the at least two distances (r1 , r2, w) are determined within a plane of the windscreen (2) of the vehicle.

12. A method according to one of the preceding claims in which determining of the arrangement (x_s, ys, z_s, β, γ, λ) comprises that an orientation (β, γ, λ) of the portable communication device (11) within the coordinate system (x, y, z) of the vehicle is determined on the basis of the sensor data.

13. A method according to claim 12 in which for determining the orientation (β, γ, λ) a roll angle (β) and/or a pitch angle (γ) and/or a yaw angle (λ) of the portable communication device (11 ) is/are determined.

14. A method according to claim 13 in which the yaw angle (λ) is determined on the basis of recorded measured values provided by an acceleration sensor whilst the vehicle is in motion, wherein the determined yaw angle (λ) is assessed as correctly determined if a predetermined calculation criterion relating to measured values provided by a compass during said motion is fulfilled.

15. A method according to claim 14 in which the calculation criterion includes the

condition that the standard deviation of a predetermined quantity of measured values provided by the compass remain below a predetermined limit value.

16. A method according to one of the preceding claims in which the arrangement (xs, ys, zs, β, y, λ) of the portable communication device (11) is determined by an internal computing unit of same portable communication device (11) or the sensor data are transmitted to a host server, the arrangement (x_s, ys, z_s, β, γ, λ) is determined by a computing unit of the host server, and data containing information about the arrangement (x_s, ys, z_s, β, γ, λ) are transmitted from the host server to the portable communication device (11).

17. A computing unit which is configured for performing a method according to one of the preceding claims.

18. A portable communication device (11) which comprises a computing unit according to claim 17.