Method and control device for determining obstacles in pivoting areas of two side doors of a motor vehicle

Abstract

A method for determining obstacles in pivoting areas of two side doors of a motor vehicle arranged on a same side thereof using multiple ultrasonic sensors comprises: determining reflection points in a lateral environment of the motor vehicle including the pivoting areas by multilateration based on distance measurements performed using the plurality of ultrasonic sensors; determining the presence or absence of obstacles in a respective pivoting area depending on whether or not there is a reflection point in the pivoting area; and, in response to opening of one of the side doors, deactivating an ultrasonic sensor arranged on a vehicle body of the motor vehicle that is monitoring the pivoting area of the opening side door, and freezing a reflection point relevant for the pivoting area of the other side door.

Description

[0001] Method and control device for determining obstacles in pivoting areas of two side doors of a motor vehicle

[0002] The present invention relates to the field of automotive ultrasonics, and, more particularly, to a method and control device for determining presence or absence of obstacles in respective pivoting areas of at least two side doors of a motor vehicle arranged on a same side of the motor vehicle using a plurality of ultrasonic sensors, and to a motor vehicle having the control device.

[0003] It is known to use ultrasonic sensors for distance measurement in a lateral environment of a motor vehicle to determine the distances to potential points of reflection at an obstacle. Using the measured distances and the known installation locations of the ultrasonic sensors, a 2D or 2.5D position of such a reflection point can be determined through multilateration. If such a reflection point is located in a pivoting area of a side door of the motor vehicle, the side door may be prevented from opening or a warning may be issued to the driver.

[0004] When one of the ultrasonic sensors is mounted not on the side door, but on the vehicle body, such as in a door sill, and one of the side doors is actually being opened, the ultrasonic sensor will see the door as an obstacle and this would lead to a false warning or to blocking of further opening of the door. However, if the ultrasonic sensor that falsely identifies the opening door as an obstacle is deactivated to prevent the false warning or erroneous blocking of further opening, the detection performance of the overall ultrasonic system degrades and the detection accuracy of obstacles in neighbouring pivoting areas is decreased.

[0005] With these problems in mind, an object of the present invention is to improve the ultrasonic detection accuracy of obstacles in a lateral environment of a four- or five-door motor vehicle when one of the doors is being opened.

[0006] Accordingly, under a first aspect, there is proposed a method for determining presence or absence of obstacles in respective pivoting areas of at least two side doors of a motor vehicle arranged on a same side of the motor vehicle using a plurality of ultrasonic sensors. The method comprises: determining a number of reflection points in a lateral environment of the motor vehicle including the pivoting areas by multilateration based on distance measurements performed using the plurality of ultrasonic sensors; determining the absence of obstacles in a respective pivoting area if there is no reflection point in the pivoting area; and, in response to opening of one of the side doors, deactivating an ultrasonic sensor arranged on a vehicle body of the motor vehicle that is monitoring the pivoting area of the opening one of the side doors, and freezing a reflection point relevant for the pivoting area of the one or more other ones of the side doors.

[0007] Accordingly, degradation of the quality of reflection points determined in the pivoting area of the other side door(s), that would result from deactivating the ultrasonic sensor monitoring the pivoting area of the one side door, which is not able to take part in multilateration after being deactivated, is advantageously avoided by freezing the reflection points that were determined before the ultrasonic sensor monitoring the pivoting area of the one side door was deactivated.

[0008] Thus, advantageously it is possible to reduce the risk of blocking of the other side door(s) through false detection of a reflection point inside their pivoting area when there is actually no obstacle in their pivoting area, and / or of erroneously clearing the other side door(s) for opening through false detection of a reflection point outside their pivoting area when there is actually an obstacle in their pivoting area.

[0009] Herein, for example, a reflection point that is “relevant for a pivoting area” may be a reflection point that is in the specific pivoting area, or may be a reflection point that is located in an area that comprises the pivoting area and an additional safety buffering zone that covers for potential errors in determining the exact position of the reflection point, and / or may be a reflection point that was seen, or that was seen with the highest amplitude, by an ultrasonic sensor that is monitoring the pivoting area. Herein, “freezing” of a reflection point may refer to one or more of prolonging a validity period, exempting from deletion and the like, of either the entire reflection point or at least of its coordinates and / or at least one further attribute associated with the reflection point such as a height indication, a confidence level, and the like.

[0010] A reflection point may be a 2D reflection point designated by two-dimensional coordinates in a vertical projection of the vehicle and its surroundings onto the road plane, or may be a 2.5D reflection point designated by the two-dimensional coordinates and an additional height indication that classifies the reflection point as one of “high” and “low”, wherein a “low” 2.5D reflection point indicates an obstacle, such as a kerbstone, over which a side door of the vehicle can pivot without being damage, and “high” indicates an obstacle that might collide with the pivoting side door. A “high” / ”low” indication may be obtained by observing the number of peaks in an ultrasound signal reflected from the obstacle towards one of the ultrasonic sensors. A “high” object may be identified in case of two or more peaks, while a “low” obstacle may be identified in case of a single peak.

[0011] Similarly, the pivoting area of a side door can be understood as a 2D area in a vertical projection of the vehicle and its surroundings onto the road plane through which the corresponding side door of the vehicle pivots when being opened, being open, and being closed. Alternatively, the pivoting area may be defined in 2.5D or 3D such that “low” reflection points that would be within the pivoting area in the vertical projection onto the road plane are considered to be outside the pivoting area and only “high” reflection points are considered to be “in” the pivoting area.

[0012] That is, in particular, a reflection point being “in the pivoting area” shall be construed such that the reflection point is in the pivoting area such that an obstacle located at the reflection point’s position would constitute an actual obstacle to the opening of the corresponding side door. Mu Itilateration may comprise determining the two-dimensional coordinates of the reflection points based on distance measurements performed by at least two ultrasonic sensors and the known installation positions of the at least ultrasonic sensors. Multilateration also comprises, as a special case, trilateration, in which distances measurements and installation positions of exactly two ultrasonic sensors are being used.

[0013] It goes without saying that presence of an obstacle in one of the pivoting areas is detected when there is at least one reflection point in the respective pivoting area, and absence of obstacles in one of the pivoting areas is detected when there is no reflection point in the respective pivoting area.

[0014] In response to determining presence of an obstacle in one of the pivoting areas, a signal may be generated that blocks opening of the corresponding door or causes opening of the corresponding door to be restrict to an angle at which the door does not collide with an obstacle located at the closest one of the one or more reflection points in the pivoting area.

[0015] In response to determining absence of an obstacle in one of the pivoting areas, a signal may be generated that clears the corresponding door for being opened.

[0016] The respective signal may be provided to a door control ECU of the motor vehicle and / or as a warning or information signal to the driver or a passenger of the motor vehicle.

[0017] “In response to opening” of a side door may be construed as “in response to the side door starting an opening process” and / or “in response to the side door being in an open state”. Whether the side door starts opening and / or is in an open state may be determined by a sensor that measures a position of the door, a sensor that measures contact of the door with the vehicle body, or the like, and / or may be inferred based on information supplied by a door control ECU that controls automatic opening and closing of the side door, for example. An ultrasonic sensor that monitors a pivoting area may be, for example, one or more of: an ultrasonic sensor, the field of view of which intersects with the pivoting area; an ultrasonic sensor, the field of view of which has a substantial overlap with the pivoting area; and an ultrasonic sensor, the axis of view of which extends within and / or at least intersects the pivoting area.

[0018] “Deactivating” a respective ultrasonic sensor may, in particular, refer to one or more of: not considering data supplied by the ultrasonic sensor, instructing the ultrasonic sensor not to transmit data and / or turning off the ultrasonic sensor and / or a power supply of the ultrasonic sensor.

[0019] The motor vehicle may be a four-door or a five-door passenger vehicle which has two side doors on each side of the motor vehicle, however there is no limitation to this, and the motor vehicle may also have three or more doors on each side.

[0020] In particular, the two ore more side doors on a same side of the motor vehicle may be regarded as being arranged behind each other in the front-rear direction of the motor vehicle. That is, the two or more side doors on the same side may be neighbouring side doors.

[0021] In the present description, the term “a number of” designates a number of one or more, while the term “a plurality of” designates a number of two or more.

[0022] Preferably, the proposed method is being performed while the motor vehicle 1 is in a stationary state, such as in state in which the motor vehicle 1 is parked.

[0023] According to an embodiment, the distance measurements are performed repeatedly in cycles; the determined reflection points are adjusted or deleted and redetermined in each cycle; freezing a reflection point comprises exempting the reflection point from being adjusted or deleted during future cycles, and the frozen reflection point remains frozen until the opened one of the side doors is closed again. In particular, the case where the reflection points are adjusted in each cycle may comprise a case in which a control unit of the motor vehicle maintains a continuous cloud of reflection points and uses distance measurements of each cycle to update the cloud of reflection points rather than deleting and redetermining the reflection points from scratch. In such a case, distance measurements from several cycles can be combined to refine a reflection point step- by-step by updating (adjusting) its coordinates, height indications, confidence levels and the like.

[0024] According to a further embodiment, the determined reflection points comprise a plurality of attributes; and freezing a reflection point comprises exempting at least one of the attributes of the reflection point from being adjusted during future cycles.

[0025] That is, the freezing does not necessarily imply leaving the frozen reflection point as is, but may also imply freezing certain attributes, such as a height / indication and or the 2D coordinates, of the reflection point. In this way, advantageously, even if the reflection point (some attributes thereof) are frozen, even a frozen reflection point can disappear when the corresponding obstacle is removed from the pivoting area, but as long as the obstacle is there, the reflection point remains and its attributes stay frozen at the values that were determined at the time before one of the ultrasonic sensors was deactivated.

[0026] According to a further embodiment, the plurality of attributes comprise at least a set of two- dimensional coordinates, a binary height indication, and a confidence level.

[0027] As already mentioned above, a height indication attribute may classify the reflection point as one of “high” (such that the pivoting side door would collide with the corresponding obstacle) and “low” (such that the pivoting side door can pivot over the corresponding obstacle without a collision), such that the reflection point is a 2.5D reflection point described by the two-dimensional coordinates and the height indication. A confidence level may be determined based on the number of ultrasonic sensors that contributed to the multilateriation of the two-dimensional coordinates, based on statistical errors when determining the position of the reflection point through multilateration while applying regression methods, or the like.

[0028] Such a confidence level is likely to decrease when one of the ultrasonic sensors is deactivated and may degrade up to a point where the reflection point is no longer being considered as being “in the pivoting area” due to its confidence level being too low.

[0029] Similarly, a height indication may degrade because a height may not be determined reliably by a reduced number of ultrasonic sensors.

[0030] By freezing the confidence level and / or the height indication at the value prior to deactivating one of the ultrasonic sensors, such a degradation of a relevant reflection point can be advantageously avoided.

[0031] According to a further embodiment, the one of the side doors is considered to be opening when an opening angle of the side door has become greater than a predetermined threshold.

[0032] The predetermined threshold may be selected such that the door is considered to be opening only when it is opened sufficiently such that the door becomes visible as a false obstacle to the ultrasonic sensor that is going to be disabled.

[0033] Thus, advantageously, a slight opening of the side door may not cause the ultrasonic sensor to be deactivated.

[0034] According to a further embodiment, after deactivating the ultrasonic sensor arranged on the vehicle body that is monitoring the pivoting area of the opening one of the side doors, a proximity sensor arranged on the outside of the opening one of the side doors is used to monitor a portion of the pivoting area of the opening one of the side doors outside the opening one of the side doors.

[0035] The proximity sensor may be another ultrasonic sensor or may be another ultrasonic sensor that does not take part in the multilateration of reflection points at least once the side door on which it is installed starts opening, or may be another type of proximity sensor, such as an infrared sensor, a camera, and the like.

[0036] Thus, advantageously, the opening side door is protected from collisions with newly appearing obstacles in its pivoting area even though the ultrasonic sensor that monitors its pivoting area is deactivated.

[0037] According to a second aspect, there is proposed a computer program product comprising instructions that, when carried out by a control device of a motor vehicle that is connected with a plurality of ultrasonic sensors arranged on a vehicle body of the motor vehicle, cause the control device to perform the method of the first aspect or any of its embodiments.

[0038] The computer program product, such as a computer program means, may be embodied as a memory card, USB stick, CD-ROM, DVD or as a file which may be downloaded from a server in a network. For example, such a file may be provided by transferring the file comprising the computer program product from a wireless communication network.

[0039] According to a third aspect, there is provided a control device of a motor vehicle having at least two side doors arranged on a same side of the motor vehicle and configured to determine presence or absence of obstacles in respective pivoting areas of the at least two side doors using a plurality of ultrasonic sensors, the control device comprising: a first unit configured to determine reflection points in a lateral environment of the motor vehicle including the pivoting areas by multilateration based on distance measurements performed using the plurality of ultrasonic sensors; a second unit configured to determine the presence or absence of obstacles in a respective pivoting area depending on whether or not there is at least one reflection point in the pivoting area; and a third unit configured to, in response to opening of one of the side doors, deactivate an ultrasonic sensor arranged on a vehicle body of the motor vehicle that is monitoring the pivoting area of the opening one of the side doors, and freeze a reflection point relevant for the pivoting area of the one or more other ones of the side doors.

[0040] According to a fourth aspect, there is proposed a motor vehicle comprising: at least two side doors arranged on a same side of the motor vehicle; a plurality of ultrasonic sensors arranged on a vehicle body of the motor vehicle so as to monitor a respective pivoting area of a respective one of the at least two side doors; and the control device of the third aspect.

[0041] According to an embodiment of the fourth aspect, a respective one of the plurality of ultrasonic sensors is arranged on a door sill below the respective side door or on a pillar below or rearwards of the respective side door.

[0042] The respective unit, e.g. the first unit, second unit, and third unit, and / or the control device, may be implemented in hardware and / or in software. If said unit is implemented in hardware, it may be embodied as a device, e.g. as a computer or as a processor or as a part of a system, e.g. a computer system. If said entity is implemented in software it may be embodied as a computer program product, as a function, as a routine, as a program code or as an executable object. Furthermore, each of the presently cited units may also be part of a control system of the motor vehicle, such as for example of a central electronic control unit (ECU), an ultrasonic ECU, a door opening ECU or the like.

[0043] The embodiments, features and advantages described with reference to the method of the first aspect of the present invention apply mutatis mutandis also to each of the computer program product of the second aspect, the control device of the third aspect and the motor vehicle of the fourth aspect or its embodiment. Further possible implementations or alternative solutions of the invention also encompass combinations - that are not explicitly mentioned herein - of features described above or below with regard to the embodiments. The person skilled in the art may also add individual or isolated aspects and features to the most basic form of the invention.

[0044] Further embodiments, features and advantages of the present invention will become apparent from the subsequent description and dependent claims, taken in conjunction with the accompanying drawings, in which:

[0045] Fig. 1 shows a left side view of a motor vehicle according to an exemplary embodiment;

[0046] Fig. 2 shows a schematic projection of a left side portion of the motor vehicle of Fig. 1 from above onto the road plane;

[0047] Fig. 3 visualizes a data configuration of a reflection point according to a preferred further development;

[0048] Fig. 4 shows a functional configuration of a control device according to the exemplary embodiment; and

[0049] Fig. 5 visualizes method steps of a method according to the exemplary embodiment.

[0050] In the Figures, like reference numerals designate like or functionally equivalent elements, unless otherwise indicated.

[0051] Fig. 1 shows a left side view of a motor vehicle 1 according to an exemplary embodiment.

[0052] Note that F denotes a direction towards a vehicle front. The motor vehicle 1 comprises, on its left side as shown in Fig. 1 , a front side door 2 and a rear side door 3. The front side door 2 and the rear side door 3 are arranged behind each other in the vehicle front-rear direction. That is, the front side door 2 and the rear side door 3 are neighbouring side doors of the motor vehicle 1 . A plurality of ultrasonic sensors 4, 41 -45 are arranged along a door sill 8 of the motor vehicle 1 below the side doors 2, 3. It is noted that the ultrasonic sensors 41 and 45 are optional and it suffices if at least one ultrasonic sensor 42, 43 is arranged on the door sill 8 below the respective side door 2, 3 so as to monitor a respective pivoting range (not shown in Fig. 1 ; elements 20, 30 in Fig. 2) of the respective side door 2, 3. Optionally, a respective proximity sensor 62, 63 is provided near a door handle on a respective of the side doors 2, 3. Furthermore, the motor vehicle 1 comprises a control device (not shown in Fig .1 ; element 7 in Fig. 4) for controlling an operation of the plurality of ultrasonic sensors 42, 43 and for determining presence and absence of obstacles that is described later.

[0053] Fig. 2 shows a schematic projection of a left side portion of the motor vehicle 1 of Fig. 1 from above onto the road plane. A case is considered in which only the ultrasonic sensors 42, 43 are provided on the left side of the motor vehicle 1 . Herein, again, F denotes a direction towards the vehicle front.

[0054] In Fig. 2, the side door 3 is shown as being closed, and the side door 2 is shown as being opened by an opening angle a. The pivoting area 20 is an area through which the side door 2 can pivot between a closed state and a fully opened state. The pivoting area 30 is an area through which the side door 3 can pivot between a closed state and a fully opened state.

[0055] The ultrasonic sensor 42 is arranged such that it monitors the pivoting area 20 of the front side door 2, and the ultrasonic sensor 43 is arranged such that it monitors the pivoting area 30 of the rear side door 3. That is, an axis of view 421 (centre axis of a field of view) of the ultrasonic sensor 42 extends through the pivoting area 20 of the front side door 2, and a field of view (not shown) of the ultrasonic sensor 42 has a large overlap with the pivoting area 20 of the front side door 2. Similarly, an axis of view 531 of the ultrasonic sensor 43 extends through the pivoting area 30 of the rear side door 3 and a field of view (not shown) of the ultrasonic sensor 43 has a large overlap with the pivoting area 30 of the rear side door 3. In state in which the side door 2 is closed (as shown in Fig. 1 ; unlike the state shown in Fig. 2), both ultrasonic sensors 42, 43 are activated. By means of sending out ultrasonic waves, measuring the time until an ultrasonic echo is received, and multiplying by the known speed of ultrasonic sound in air, a distance from a respective ultrasonic sensor 42, 43 to an obstacle in the lateral environment 9 (which includes pivoting areas 20 and 30) of the motor vehicle 1 can be obtained. Through trilateration, using the measured distances and the known installation positions of sensors 42, 43, a position of the reflection points 5 on presumed obstacles in the lateral environment 9, and more particularly, in the pivoting areas 20 and 30) can be obtained.

[0056] Herein, for example, reflection point 51 may indicate a high obstacle such as a pole in the lateral environment 9, and reflection point 52 may indicate a low obstacle such as a kerb in the later environment 9. Reflection points 53 and 54 are not determined when both doors 2, 3 are closed (as shown in Fig. 1 , unlike as shown in Fig. 2) and will be described later.

[0057] Fig. 3 visualizes a data configuration of a reflection point 5 (51 , 52, 53, 54) according to a further preferred development. Reference is made to Fig. 2 and Fig. 3.

[0058] The reflection point 5 comprises at least two-dimensional coordinates 501 and 502, and according to the preferred further development, the reflection point 5 further comprises further attributes, such as, for example, a height indication 503, and / or a confidence level 504, and also comprises a frozen flag 505 to be described later.

[0059] In one preferred further development, the height indication 503 is obtained, for example, by examining the number of peaks in an ultrasound signal received by the respective ultrasonic sensors 42, 43. If both ultrasound signals received by the ultrasonic sensors 42, 43 that took part in the trilateration of a reflection point 5, such as in the case of reflection point 51 , show a sequence of two peaks, the second peak being lower than the first peak, then the height indication 503 may be set to indicate a “high” object over which the side door 3 - if reflection point 51 were in its pivoting area 30, cannot pivot without collision. The reasoning behind this is that on a high obstacle such as a pole or a wall, the ultrasound signal propagates along two pathways, one pathway indicating a direct reflection only at the high obstacle, which corresponds to the first higher peak, and the other pathway having a longer time of flight indicating a double reflection first at the high obstacle and then at the road surface, which corresponds to a second, lower peak. If, on the other hand, for a reflection point 5, such as in the case of the reflection point 52, both ultrasound signals obtained by the ultrasonic sensors 42, 43 that took part in the trilateration of the reflection point 52 show only a single peak, then the height indication 503 may be set to indicate a “low” obstacle, such as a kerb, over which the side door 3 can pivot without collision.

[0060] In one preferred further development, the confidence level 504 is determined based on whether the reflection point 5 is based on measurements by a sufficient number of ultrasonic sensors 42, 43. For example, the confidence level 504 may be set to “high” if at least two ultrasonic sensors 42, 43 detected the reflection point 5, and may be set to “low” if only one of ultrasonic sensors 42, 43 detected the reflection point 5. However, confidence level 504 may also be determined based on other criteria, such as a statistical error obtained when performing multilateration using more than two ultrasonic sensors 42, 43 and using a statistical method such as linear regression to determine the 2D coordinates 501 , 502 of the reflection point 5. That is, the confidence level 504 may be a binary indication stating “high” or “low” confidence level, or may be an integer or floating point number that measures the confidence level on a continuous or quasi-continuous scale.

[0061] Returning now to the situation with an opening side door 2, as depicted in Fig. 2, with further reference to Fig. 2 and 3, the following observations are made.

[0062] When the side door 2 opens, and the opening angle a reaches a predetermined threshold angle of, for example 3° or 5°, the ultrasonic sensor 42 will start to “see” the opening side door 2 and will determine a further (non-shown) reflection point located next to the partially opened side door 2. Such a reflection point would be classified as high and would be located within the pivoting area 20 of the side door 2. The reflection point could therefore be identified as an obstacle to side door 2, and may consequently cause a false warning signal or may cause unwanted blocking of further opening of the side door 2. Therefore, it has been considered to deactivate the ultrasonic sensor 42 that monitors the pivoting range 20 of the side door 2 when said side door 2 is being opened and / or is in an open state.

[0063] However, the inventors of the present invention have identified, through experiments with test vehicles in a variety of staged and real-life scenarios, that, if deactivating an ultrasonic sensor 42 that monitors a pivoting range 20 of one of the side doors 2 while said side door 2 is being opened or is open, in some cases, problems may occur in that the other side door 3 cannot be opened even though there is no real obstacle in its pivoting area 30, and / or in that other side door 3 is cleared for being opened, but upon opening the other side door 3, a collision occurs because there was an actual obstacle in its pivoting area 30 that was overlooked.

[0064] The following explanation for these problems has been identified by making hypotheses and confirming these hypotheses with data collected during the abovementioned experiments.

[0065] Let us consider reflection point 51 , which indicates a position of a pole in the lateral environment 9. The position is obtained by trilateration of distance measurements performed with the ultrasound sensors 42 and 43. Because both ultrasound sensors 42 and 43 detected double peaks in their received signals, the height indication 504 of the reflection point 51 is set to “high”.

[0066] Let us further consider reflection point 52, which reflects a position of a kerb in the lateral environment 9. The position is obtained by trilateration of distance measurements performed with the ultrasound sensors 42 and 43. Because both ultrasound sensors 42 and 43 detected only a single peak in their received signals, the height indication 504 of the reflection point 52 is set to “low”. Accordingly, an absence of obstacles in the pivoting area 30 of the rear side door 3 can be determined correctly, because the reflection points 51 and 52 are considered to be outside the pivoting area 30 (reflection point 51 is outside pivoting area 30 in the horizontal plane, and reflection point 52 is lower than the lowest point of rear door 3, so that it is outside pivoting area 30 in the vertical direction).

[0067] Now, in the considered example, if the ultrasound sensor 42 is disabled due to the front side door 2 being open, and measurement is repeated, neither the reflection from the pole nor the reflection from the kerb can be trilaterated, because both reflections are now detected only by ultrasonic sensor 43. Consequently, in the repeated measurement, due to lack of data from any further ultrasonic sensor, reflection points 53 and 54 will be generated that are positioned on a sensor axis 431 of the only ultrasonic sensor 43 that detected these reflection points 53, 54.

[0068] For the reflection point 53 indicating the high pole, this means that unlike the correct reflection point 51 , the reflection point 53 is now located inside pivoting area 30 of rear side door 3, such that presence of an obstacle in the pivoting area 30 would be falsely detected.

[0069] For the reflection point 54 indicating the low kerb, its position does not differ much from the position of the correct reflection point 52. However, since only a single ultrasonic sensor 43 detected the reflection point 54, a confidence level 504 of the reflection point 54 is low. One may also consider that when a confidence level 504 of a reflection point 5, such as reflection point 54, 4 is low, then it cannot be safely assumed that a corresponding obstacle is a low obstacle, because a risk of missing a second peak in only a single received ultrasound signal is too high, such that, for safety reasons, one may decide to set the height indication 503 of the reflection point 54 to “high” as a safeguard. Consequently, due to falsely being identified as high, also the reflection point 54 would now be considered to be located inside pivoting area 30, resulting in false detection of an obstacle in the pivoting area 30. Reference points 53, 54 may not simply be degraded due to trilateration failing, as described hereinabove. A more gradual degradation is also conceivable, in which a confidence level, error bars or the like of reference points 53, 54 that were successfully multilaterated using a plurality of ultrasonic sensors 4 (Fig. 1 ) excluding the disabled ultrasonic sensor 42 are less favourable (lower confidence level, larger error bars) of the reference points 51 , 52 that were successfully multilaterated using a plurality of ultrasonics sensors 4 (Fig.1 ) including also ultrasonic sensor 42 when it was enabled.

[0070] In view of these findings, the inventors propose the method and control device 7 (Fig. 4) of the present exemplary embodiment.

[0071] Fig. 4 shows a functional configuration of a control device 7 according to the present exemplary embodiment; and Fig. 5 visualizes method steps of a method according to the exemplary embodiment. Reference is made to Figs. 2 to 5.

[0072] It is noted that the control device 7 is communicatively connected with the plurality of ultrasonic sensors 41 -44.

[0073] The method comprises a first flow comprising steps S10 to S30.

[0074] In step S10 of the first flow, the first unit 71 of the control device 7 determines a number of reflection points 5 in the lateral environment 9 of the motor vehicle 1 , based on distance measurements performed using the plurality of ultrasonic sensors 42, 43, as described hereinabove. Therein, for example, the first unit 71 of the control device 7 may control the plurality of ultrasonic sensors 42, 43 so as to transmit and then receive ultrasound signals, after which either the ultrasonic sensors 42, 43 or the first unit 71 perform an analysis of the received ultrasound signals, calculate the distances and obtain the trilaterated positions of the reflection points 5. In step S20, the second unit 72 of the control device 7 determines whether or not any one of the reflection points 5 is determined to be in the pivoting area 20, 30. If any reflection point 5 is in one of the pivoting area 20, 30 (Y), the method proceeds to step S30 and determines the presence of an obstacle in the respective pivoting area 20, 30. Otherwise (N), the method determines absence of an obstacle in the respective pivoting area 20, 30 and cycles back, potentially after a certain delay, to step S10.

[0075] That is, the flow comprising steps S10, S20 and S30 is performed by the first unit 71 and the second unit 72 repeatedly in cycles.

[0076] In parallel to the flow comprising steps S10, S20 and S30, third unit 73 of control device 7 performs, repeatedly in cycles, the flow comprising steps S40 to S70.

[0077] In step S40, the third unit 73 determines, based on a sensor measurement using a nonshown door opening sensor, or based on information provided by a non-shown door control system, whether any one of the side doors 2, 3 has started opening or is in an open state. If not (N), the flow cycles back, potentially after a certain delay, to step S40. If yes (Y), the flow proceeds with step S50.

[0078] In step S50, since it has been established that one of the side doors, i.e. side door 2 in the example described, is opening, the third unit 73 deactivates an ultrasonic sensor 42 that is monitoring the pivoting area 20 of the corresponding side door 2. The flow then proceeds to step S60.

[0079] In step S60, the third unit 73 of the control device 7, having deactivated the ultrasonic sensor 42 that is monitoring the pivoting area 20 of the front side door 2, checks whether there is any reflection point 5 among the reflection points 5 that have been detected before the ultrasonic sensor 42 was disabled that is relevant for the pivoting area 30 of the other side door that has not been opened, i.e. of the rear side door 3. In the example, the reflection point 52 is determined to be relevant for the pivoting area 30 because it is located inside the pivoting area 30, and the reflection point 51 is also determined to be relevant for pivoting area 30. For example, the determination of relevance of the reflection point 51 may be made because it is located within a safety buffer zone around pivoting area 30, and / or because ultrasonic sensor 43 that monitors the pivoting area 30 of the read side door 3 participated in detecting and tri- laterating a position of the reflection point 51 .

[0080] If no relevant reflection points 5 are identified (N), the flow cycles back, potentially after some delay, to step S40. If relevant reflection points 5 are identified (Y) for pivoting area 30 of the other side door 3, the flow proceeds to step S70.

[0081] In step S70, the third unit 73 freezes the reflection points 51 , 52 that have been deemed to be relevant for the pivoting area 30 of the other, rear side door 3. For example, the third unit 73 may set a frozen flag 505 comprised within the respective reflection point 5. The frozen flag 505 may be a binary flag that indicates that the entire reflection point 5 is frozen. The frozen flag 505 may also be a multi-bit flag, wherein each bit indicates, for a respective one of each of the attributes 501 -504, whether the respective attribute is frozen.

[0082] The flow then cycles back, potentially with some delay, to step S40.

[0083] Step S10 of the flow comprising steps S10 to S30 carried out by first and second units 71 , 72 of control device 7 is now described in more detail.

[0084] If, at the time when cycling back to S10, there is at least one reflection point 5 determined in the previous cycle that has a frozen flag 505, the first unit 71 , in step S10, carries over the frozen information from the previous cycle to the current cycle.

[0085] In the exemplary embodiment, the first unit 71 deletes all reflection points 51 , 52 determined in the last cycle before starting the current cycle. Now, for example, if reflection point 51 is frozen in its entirety (has a frozen flag 505 indicating freezing of the whole reflection point 51), the first unit 71 carries over such a reflection point 51 to the present cycle, i.e., the frozen reflection point 51 is exempted from deletion, such that the present cycle will operate with determined reflection points 53, 54, and 51. The first unit 10 may determine, for example based on reflection points 51 , 53 having the same distance to ultrasonic sensor 53, that both reflection points 51 , 53 represent the same obstacle, and may give preference to the carried- over frozen reflection point 51 that is exempted from deletion, and may delete reflection point 53 as being a less-accurate representation of the same obstacle, so that ultimately, step S20 will be performed based on the older reflection point 51 and the new reflection point 54.

[0086] According to a preferred development, the first unit 71 may not delete the reflection points 51 , 52 determined in the last cycle, but may perform processing to determine a correspondence relationship between all reflection points 51 , 52 determined in the past cycle and all reflection points 53, 54 determined in the current cycle. For combination of reflection points 51 , 53, and 52, 54 that have been determined to correspond to each other, the first unit 71 may then perform merging processing. In the merging processing, normally, the reflection points 53, 54 determined in the current cycle have precedence over the reflection points 51 , 52 determined in the previous cycle. However, the first unit carries over frozen attributes of the reflection points 51 , 52 of the previous cycle into the corresponding reflection points 53, 54 of the current cycle.

[0087] Thus, for example, if reflection point 52 determined in the previous cycle has a multi-bit frozen flag 505 indicating the freezing of, for example, its height attribute 503 and / or its confid- dence level attribute 504, the first unit 71 carries over the frozen height attribute 503 and / or the frozen confidence level attribute 504 into the corresponding reflection point 54, whereas the coordinates 501 , 502 of reflection point 52 are not carried over and coordinates 501 , 502 of reflection point 54 are used as determined.

[0088] After carrying over the frozen attributes 503, 504, the first unit 71 may then delete the reflection points 51 , 52 determined in the previous cycle, and may keep the reflection points 53, 54 determined in the current cycle, some of which may be merged reflection points 53, 54, in which certain attributes, such as the coordinates, were determined in the current cycle, but one or more attributes may be frozen attributes carried over from a determination of a previous cycle.

[0089] In both examples, identification of correspondence relationships between reflection points 5 of different cycles may be based on proximity, similarity of shapes, similarity of ultrasound signals, and the like, using analytical and / or statistical tracking methods and / or a machine- learned artificial intelligence, for example.

[0090] That is, with regards to the example shown, the freezing of reflection points may result in reflection point 53 “moving back” to the position of reflection point 51 , which is outside the pivoting area 30. Freezing of certain attributes of reflection point 52 may lead to the height indication attribute 502 and / or the confidence level attribute 503 being exempted from adjustment and being carried-over and conserved, such that also reflection point 54 is identified as being “low” and therefore outside the pivoting area 30.

[0091] Thus, the freezing of reflection points 51 , 52 determined to be relevant for the pivoting area 30 of the other side door 3 in response to opening of the one side door 2 and deactivating the ultrasonic sensor 42 monitoring the pivoting area 20 of the one side door 2 can advantageously prevent a situation in which a false determination of the presence of obstacles in the pivoting area 30 of the other side door 3 would otherwise occur due to degradation of the reflection points 53, 54 determined with a reduced number of ultrasonic sensors 4.

[0092] The reflection points 51 , 52, 53, 54 that were discussed hereinabove are illustrative examples. In these examples, the case was examined in where “phantom” “high” obstacles are detected in the pivoting area 30 of the other side door 3 and the freezing of relevant reflection points 51 , 52 can prevent such false detections and clear the other side door 3 for opening. However, it will be appreciated that in a practical use case, the opposite case may also occur, i.e., due to degradation of detection precision after deactivating one of the ultrasonic sensors 42, it can also happen that a reflection point 5 resulting from a high obstacle is misclassified as being “low”, or in that a reflection point 5 resulting from an obstacle located inside a pivoting area 30 is falsely determined to be outside of the pivoting area 30. Also in this case, by freezing relevant reflection points 51 , 52 obtained at a time when the ultrasonic sensor 42 was not yet deactivated may improve the detection quality such that the high obstacles in the pivoting area 30 are correctly detected and a false detection of absence of obstacles is avoided also after deactivation of one of the ultrasonic sensors 42, such that the other side door 3 can be prevented from being opened and a collision can be avoided.

[0093] It will be appreciated that more generally, the freezing of reflection points 5 determined to be relevant for the pivoting area 20, 30 of another side door 2, 3 before deactivating the ultrasonic sensor 41 , 42 monitoring the pivoting area 20, 30 of one side door 2, 3, preferably while at the same time allowing further reflection points 5 to be added for later-appearing obstacles, can advantageously mitigate the effects of the degradation of the accuracy of detecting the presence or absence of obstacles in the pivoting area 20, 30 of the other side door 2, 3 that results from deactivating the ultrasonic sensor 41 , 42 monitoring the pivoting area 20, 30 of the one side door 2, 3 in a situation where the motor vehicle 1 is parked and the one side door 2, 3 is opening or is in an opened state and the other side door 2, 3 is still closed.

[0094] Also, hereinabove, the case of opening front side door 2 as the one side door 2 and freezing reflection points relevant for the pivoting area 30 of rear side door 3 as the other side door 3 has been described, however, similar flows and configurations may be applied to the case of opening rear side door 3 as the one side door 3 and freezing reflection points relevant for pivoting area 20 of front side door 2 as the other side door 2.

[0095] It will be appreciated that a reflection point 5 that is frozen by setting the frozen flag 505 is not frozen eternally. For example, the reflection point 5 may comprise a further field that specifies for how long the reflection point 5 is frozen if the frozen flag 505 is set. Alternatively, according to a preferred further development, a fourth unit (non-shown) of control device 7 performs a process flow in which the fourth unit periodically checks whether a side door 2, 3 that was previously open has been closed. In case the side door 2, 3 has been closed, the fourth unit may then unfreeze and / or delete the frozen reflection points 5 and / or their frozen attributes.

[0096] According to another further preferred development, with reference to Fig. 1 and Fig. 2, the side doors 2, 3 are each equipped with a respective proximity sensor 62, 63. For example, proximity sensor 62 is used to detect any newly-appearing obstacles for the pivoting side door 2 in a portion 21 of side door’s 2 pivoting region 20 that is outside of the opening side door 2 while the side door 2 is in the process of opening. A corresponding configuration with a proximity sensor 63 is also used for side door 3 when opening. Thanks to the proximity sensors 62, 63, the side doors 2, 3 can be protected from collisions with newly-appearing obstacles even during a time when the ultrasonic sensor 42, 43 monitoring their respective pivoting areas 20, 30 are deactivated.

[0097] Although the present invention has been described in accordance with an exemplary embodiment, it is obvious for the person skilled in the art that various modifications are possible within the scope of the attached claims.

[0098] The exemplary embodiment has been described for a left side of a motor vehicle 1 , however, it will be appreciated that similar configurations can also be used on the right side of the motor vehicle 1 .

[0099] Configurations described for the opening front side door 2 and the pivoting area 30 of the other, back side door 3 are equally applicable to the back side door 2 opening and the pivoting area 20 of the other, front side door 3.

[0100] The exemplary embodiment shows a motor vehicle 1 having two neighbouring doors on each side, however, it will be appreciated that the exemplified configurations and concepts are also applicable to a vehicle having two or more neighbouring doors on at least one of its sides.

[0101] In the exemplary embodiment, a distinctive control device 7 comprising the first to third units 71 -73 and optionally a non-shown fourth unit has been described. However, control device 7 must not be a separate hardware unit, and first to third units 71 -73 and the optional noneshown fourth unit can also be part of some other higher-order control device of motor vehicle 1 , such as an ultrasound ECU, a door-opening ECU or a central ECU. That is, for example the “control device 7” can also be implement as a computer program product or the like executing on a generic computing device, such that the generic computing device forms the functionality of the first to third units 71 -73 and the optional fourth unit, and the generic computing device may also execute another computer program so as to embody further functionality such as door opening control, motor control and the like.

[0102] In the exemplary embodiment, the ultrasonic sensors 42, 43 are arranged on a door sill 8 below the side doors 2, 3. However, a respective ultrasonic sensor 42, 43 monitoring a respective pivoting area of the respective side door 2, 3 may also be arranged on a different vehicle body part of the motor vehicle 1 , such as on a B pillar or on a C pillar, etc., for example.

[0103] It will be appreciated that further ultrasonics sensors 4, such as ultrasonic sensors 41 , 45, may be provided, and it is conceiveable that more than one ultrasonic sensor 4 monitors the pivoting area 20, 30 of any one of the side doors 2, 3. Herein, if there is the danger that any of the further ultrasonic sensors 41 , 45 may also see an opening side door 2, 3 and detect it as a false obstacle, also the further ultrasonic sensors 41 , 45 may be deactivated when the corresponding side door 2, 3 opens. Herein, preferably, an individual threshold opening angle of the side door 2, 3 starting from which the respective ultrasonic sensor 41 , 45 starts to see the opening side door 2, 3 and will be disabled may be configured individually and differently for each of the plurality of ultrasonic sensors 4. The advantages of the exemplary embodiment have been described, for easier understanding, using a highly abstract case in which the deactivating of ultrasonic sensor 42 leads to trilateration to fail in the next cycle such that all further-determined reflection points 53, 54 are positioned on the sensor axis 431 . However, the skilled person will appreciate that also in a case where further ultrasonic sensors 4 are provided, and in which the deactivating of ultrasonic sensor 42 after a cycle does not lead to trilateration to fail in the next cycle, the later tri- laterated reflection points 53, 54 may still degrade by now having larger error bars, lower levels of confidence, falsely identified height attributes, and the like, such that the proposed freezing of the reflection points 51 , 52 and / or their attributes from the previous cycle in which no ultrasonic sensor 42 was deactivated also achieve the advantages of improving the accuracy of the detection of presence or absences of obstacles in the respective pivoting areas 20, 30 in these cases.

[0104] The process flow comprising cyclic execution of steps S10-S30 and cyclic execution of steps S40 to S70 has been described as executing the flow comprising steps S10-S30 and the flow comprising steps S40-S70 in parallel. However, this is not a limitation, and the two flows may also be merged into a single flow. For example, one sequence of steps S40-S70 may be performed as part of the first flow comprising steps S10-S30, for example by executing one sequence of steps S40-S70 prior to cycling back, from step S20 or step S30, to step S10.

[0105] In the discussion of the processing of the first unit 71 with regards to identifying correspondence relationships between reflection points 5 from different cycles, deleting reflection points 5, and freezing reflection points 5 and / or their attributes 501-504, two cases were described: The case where the first unit 71 deletes all reflection points 5 from the previous cycle other than the frozen reflection points 5, and deletes the reflection points 5 from the new cycle that correspond to the frozen reflection points 5 of the previous cycle; and the case where the first unit 71 determines correspondence relationships between all reflection points 5 of a previous cycle and all reflection points 5 of a current cycle. Both cases are simple abstract cases described mainly for ease of understanding. The skilled person will appreciate that in a practical scenario, some reflection points 5 may “flicker”, that is, a reflection point 5 corresponding to a given obstacle may not be determined in every cycle, but only in some cycles, and may be absent from some other cycles, necessitating modifications of the described processing. Accordingly, for example, the first unit may, in another exemplary embodiment, continuously maintain a cloud of reflection points 5, and may update the maintained point cloud based on determinations (determined reflection points 5) made in a plurality of measurement cycles. In said updating of the reflection points 5 maintained in the point cloud, if any two reflection points 5 from any two cycles are identified as corresponding to each other, normally, the reflection point 5 from the later cycle and / or attributes 501 -504 determined in the later cycle take precedence in being taken over into the point cloud over the reflection point 5 and / or attributes 501 -504 determined in the earlier cycle. However, if a reflection point 5 from the earlier cycle and / or certain attributes 501 / 504 thereof are flagged as being frozen, then the frozen reflection point 5 and / or the certain frozen attributes 501 / 504 thereof of the earlier cycle take precedence over a correspond- ing reference point 5 and / or the corresponding certain attributes 501 -504 thereof of the later cycle.

[0106] BEZUGSZEICHENLISTE

[0107] 1 motor vehicle

[0108] 2 front side door

[0109] 3 rear side door

[0110] 5 reflection points

[0111] 7 control device

[0112] 8 door sill

[0113] 9 lateral environment of motor vehicle

[0114] 20 pivoting area of front side door

[0115] 21 portion of pivoting area outside front side door

[0116] 30 pivoting area of rear side door

[0117] 41-44 ultrasonic sensor

[0118] 51-54 reflection point

[0119] 62, 63 proximity sensor

[0120] 71 first unit

[0121] 72 second unit

[0122] 73 third unit

[0123] 421 axis of view (centre axis of field of view) of ultrasonic sensor 42

[0124] 431 axis of view (centre axis of field of view) of ultrasonic sensor 43

[0125] 501 , 502 2D coordinates

[0126] 503 height indication attribute

[0127] 504 confidence level attribute

[0128] 505 frozen flag

[0129] S10-S70 method steps

[0130] F direction towards vehicle front a opening angle of front side door

Claims

PATENTANSPRUCHE1 . A method for determining presence or absence of obstacles in respective pivoting areas (20, 30) of at least two side doors (2, 3) of a motor vehicle (1 ) arranged on a same side of the motor vehicle (1 ) using a plurality of ultrasonic sensors (41 -44), the method comprising: determining (S10) a number of reflection points (5) in a lateral environment (9) of the motor vehicle including the pivoting areas (20, 30) by multilateration based on distance measurements performed using the plurality of ultrasonic sensors (41 -44); determining (S20, S30) the presence or absence of obstacles in a respective pivoting area (20, 30) depending on whether or not there is at least one reflection point (5) in the pivoting area (20, 30); and in response to opening of one of the side doors (2), deactivating (S50) an ultrasonic sensor (42) arranged on a vehicle body of the motor vehicle (1 ) that is monitoring the pivoting area (20) of the opening one of the side doors (2), and freezing (S70) a reflection point (51 , 52) relevant for the pivoting area (30) of the one or more other ones of the side doors (3).

2. The method of claim 1 , wherein the distance measurements are performed repeatedly in cycles; the determined reflection points (5) are adjusted or deleted and redetermined in each cycle; freezing a reflection point (4) comprises exempting the reflection point (5) from being adjusted or deleted during future cycles, and the frozen reflection point (5) remains frozen until the opened one of the side doors (2) is closed again.

3. The method of claim 1 or 2, wherein the determined reflection points (5) comprise a plurality of attributes (501 -504); and freezing a reflection point (5) comprises exempting at least one of the attributes (501 -4. The method of claim 3, wherein the plurality of attributes (501 -504) comprise at least a set of two-dimensional coordinates (501 , 502), a binary height indication (503), and a confidence level (504).

5. The method of any one of the preceding claims, wherein the one of the side doors (2) is considered to be opening when an opening angle (a) of the side door (2) has become greater than a predetermined threshold.

6. The method of any one of the preceding claims, wherein wherein after deactivating the ultrasonic sensor (42) arranged on the vehicle body that is monitoring the pivoting area (20) of the opening one of the side doors (2), a proximity sensor (62) arranged on the outside of the opening one of the side doors (2) is used to monitor a portion (21 ) of the pivoting area (20) of the opening one of the side doors (2) outside the opening one of the side doors (2).

7. A computer program product, comprising instructions that, when carried out by a control device (7) of a motor vehicle (1 ) that is connected with a plurality of ultrasonic sensors (41 -44) arranged on a vehicle body of the motor vehicle (1 ), cause the control device (7) to perform the method of any one of claims 1 to 6.

8. A control device (7) of a motor vehicle (1 ) having at least two side doors (2, 3) arranged on a same side of the motor vehicle (1 ) and configured to determine presence or absence of obstacles in respective pivoting areas (20, 30) of the at least two side doors (2, 3) using a plurality of ultrasonic sensors (41 -44) , the control device (7) comprising: a first unit (71 ) configured to determine reflection points (5) in a lateral environment (9) of the motor vehicle (1 ) including the pivoting areas (20, 30) by multilateration based on distance measurements performed using the plurality of ultrasonic sensors (41 -44);a second unit (72) configured to determine the presence or absence of obstacles in a respective pivoting area (20, 30) depending on whether or not there is at least one reflection point (5) in the pivoting area (20, 30); and a third unit (73) configured to, in response to opening of one of the side doors (2), deactivate an ultrasonic sensor (42) arranged on a vehicle body of the motor vehicle (1 ) that is monitoring the pivoting area (20) of the opening one of the side doors (2), and freeze a reflection point (51 , 52) relevant for the pivoting area (30) of the one or more other ones of the side doors (3).

9. A motor vehicle (1 ) comprising: at least two side doors (2, 3) arranged on a same side of the motor vehicle (1 ); a plurality of ultrasonic sensors (41 -44) arranged on a vehicle body of the motor vehicle (1 ) so as to monitor a respective pivoting area (20, 30) of a respective one of the at least two side doors (2, 3); and the control device (7) of claim 8.

10. The motor vehicle of claim 9, wherein a respective one of the plurality of ultrasonic sensors (41 -44) is arranged on a door sill (8) below the respective side door (2, 3) or on a pillar below or rearwards of the respective side door (2, 3).

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