Obstacle detection device and method for automatic calibration of such a device.

Abstract

The invention relates to a method for calibrating an obstacle detection device (1) (4) mounted on an opening (2) and comprising a radar (6). The method comprises an identification step consisting of using data from the radar (6) to determine the measured positions, within the field of view, relative to a reference frame linked to the radar (6), of a plurality of predetermined and distinct reference points (13) located on the vehicle, represented by a set of measured coordinates. The identification step is followed by a comparison step consisting of comparing the measured position of each reference point (13) to an expected position of the same reference point (13), stored in a memory of the device (1). The method comprises a calibration step consisting of determining a repositioning matrix enabling the correlation of each set of measured coordinates to the corresponding set of expected coordinates. (Figure 1)

Description

Title of the invention: Obstacle detection device and method for automatic calibration of such a device.

[0001] The technical field relates to obstacle detection devices for a vehicle opening, calibration methods for such a device and finally vehicles equipped with such devices.

[0002] Car manufacturers offer their customers various options for equipping their vehicles, including motorized tailgates that allow the trunk to be opened automatically with a simple control, thanks to motorized actuators. Motorized tailgates are particularly appealing to customers who consider such a feature a significant improvement in the comfort offered by their vehicle. From the car manufacturers' perspective, motorized tailgates present considerable technical challenges and constraints.

[0003] Indeed, it is essential to prevent the motorized rear hatch from impacting an obstacle in its opening path during its opening, such as a garage ceiling, a pillar, or a wall located too far away to allow the rear hatch to fully open. To this end, car manufacturers generally equip motorized rear hatches with obstacle detection systems capable of interacting with the actuators that move the rear hatch in order to stop its movement before it impacts the detected obstacle. These systems typically include a radar located within a space inside the rear hatch, usually between a lining and the rear hatch skin. The radar is then able to detect the presence of obstacles through the rear hatch skin.It allows, in the event of an obstacle being detected in the opening path, the shutter to be automatically stopped approximately 8 cm from the detected obstacle, generally thanks to a computing unit communicating with the radar and the motorized actuators. Such systems are described, for example, in US document 10877146.

[0004] Obstacle detection systems must be calibrated at least once during commissioning to ensure the system can correctly determine the relative position of detected obstacles with respect to the rear flap's trajectory. This calibration step is particularly necessary to account for mounting variations in the position and / or orientation of the radar on the vehicle. The calibration step is performed manually on the vehicle assembly line, requiring specific tooling and consuming assembly operator time.

[0005] In order to make an option offering a motorized shutter economically attractive, it is necessary to reduce the production costs of the specific equipment. Therefore, there is a need for a solution that reduces production costs related to the calibration stage, as well as improves the accuracy of these obstacle detection systems.

[0006] The present invention aims to overcome the problems described above. In this technical context, one objective of the present invention is to provide a method for the automatic calibration of an obstacle detection device and to provide a device capable of implementing such a method.

[0007] To this end, the present invention relates to a method for calibrating an obstacle detection device mounted on a motor vehicle opening, the device being of the type comprising a radar fixed to the vehicle, the method comprising an identification step consisting of exploiting the data from a radar scan of its field of observation to determine the positions measured in the field of observation, with respect to a reference frame linked to the radar, of a plurality of predetermined and distinct reference points arranged on the vehicle, each measured position being represented by a set of measured coordinates, the identification step being followed by a comparison step consisting of comparing the measured position of each reference point to an expected position of the same reference point, in the same reference frame linked to the radar,Since each expected position is represented by a set of expected coordinates stored in the device's memory, the process includes a calibration step consisting of determining a repositioning matrix that correlates each set of measured coordinates to the corresponding set of expected coordinates.

[0008] The invention also relates to an obstacle detection device, designed to be fixed on a motorized opening of a motor vehicle, the device comprising a radar capable of detecting an obstacle in its field of observation, the device further comprising at least one memory designed to store a plurality of sets of expected coordinates, the device comprising a control unit designed to execute the method according to the invention in order to determine a repositioning matrix.

[0009] The invention finally relates to a vehicle comprising at least one device according to the invention.

[0010] Thus, the method according to the invention offers an alternative to the manual calibration step previously used. The use of predetermined, distinct reference points linked to the vehicle makes the method dependent solely on the vehicle and the radar installation. A device according to the invention, implementing the calibration method, is then able to correct alignment and / or radar mounting. Such a device may optionally implement the calibration process during its initial commissioning and / or at predetermined time intervals; the device is then always correctly calibrated, without the intervention of an operator.

[0011] According to one embodiment of the invention, the parameters of the repositioning matrix are stored in a memory of the device.

[0012] According to one embodiment of the process, the identification step determines the measured positions of three reference points forming a three-dimensional reference frame.

[0013] According to one possibility of the calibration process, the repositioning matrix is ​​representative of a translation and / or a rotation in the reference frame linked to the radar.

[0014] According to one possibility, the device is designed to be fixed to a rear flap of a motor vehicle.

[0015] According to one embodiment of the device, at least three reference points correspond to fixing points of a windshield wiper motor.

[0016] The invention will be better understood upon reading the following detailed description, given solely by way of non-limiting example and made with reference to the accompanying drawings in which:

[0017] [Fig-1] [Fig.1] represents a schematic view of a cross-section of a vehicle showing a motorized opening equipped with an obstacle detection device according to the invention;

[0018] [Fig.2] [Fig.2] represents a schematic view showing the relationship between measured positions of reference points and the expected positions of the same reference points.

[0019] In these figures, the same references are used to designate the same elements.

[0020] A calibration method according to the invention makes it possible to calibrate an obstacle detection device 1, illustrated in [Fig.1], mounted on a motorized opening 2 of a motor vehicle, such as a rear flap 3. In a conventional manner, the opening 2 is, for example, provided with motorized cylinders, not shown, as well as appropriate control means to control these cylinders.

[0021] The device 1 is designed to detect an obstacle 4 that may be present in the space covered 5 by the opening 2 during its motorized opening, in order to stop the movement of the opening 2 before impact with the possible detected obstacle 4. In order to detect the obstacles 4, the device 1 includes at least one radar 6 capable of scanning the space covered 5 by the opening 2 during its opening. The radar 6 typically has an active face 7 allowing it to scan an observation field 8 located opposite this active face 7. Thus, the covered space 5 is scanned in one or more times according to the dimensions of the observation field 8 of the radar 6.

[0022] Conventionally, the obstacle detection device 1 is designed to stop the movement of the opening 2 when the latter is located a few centimeters from the obstacle 4 hindering the opening of the opening 2, for example, at a distance between 5 cm and 10 cm. To this end, the device 1 includes at least one control unit, not shown, capable of processing the information from the radar 6 to identify the obstacles 4 and to command the stopping of the movement of the opening 2.

[0023] In the embodiment illustrated in [Fig. 1], the opening 2 comprises an internal volume 9 delimited by a shutter lining 10 and a shutter skin 11. The radar 6 is disposed in this internal volume 9 and is, for example, fixed to the shutter lining 10 so that the active face 7 is able to observe an internal face of the shutter skin 11 and the covered space 5 through the shutter skin 11. Furthermore, the shutter skin 11 serves as a support for a window washer motor 12 disposed in the internal space 9, the window washer motor 12 facing the active face 7 of the radar 6 so as to be in the observation field 8 of the latter.

[0024] To ensure that the device 1 is able to avoid impact with the obstacle 4, it is necessary to calibrate the device 1 at least once, for example, during its initial commissioning, when the vehicle is on the vehicle assembly line. This calibration step ensures that the device 1 assigns a correct position to the detected obstacles 4 relative to the covered space 5. To this end, the control unit of the device 1 is designed to perform the method according to the invention in order to determine a repositioning matrix MR. The method according to the invention allows this calibration to be performed automatically, without the intervention of an operator.It includes an identification step consisting of exploiting the data from the scan of the observation field 8 of the radar 6 to determine the measured positions in the observation field 8, relative to a reference frame linked to the radar 6, of a plurality of predetermined and distinct reference points 13 arranged on the vehicle, each measured position being represented by a set of measured coordinates Ai. Each set of measured coordinates Ai is, for example, made up of a distance and angular measurements in order to characterize the measured position of the relevant reference point 13, relative to a preferred location positioned on the active face 7 of the radar 6. In this case, the method according to the invention implements an identification step that determines the sets of measured coordinates Al, A2, A3 of three reference points 13 forming a three-dimensional reference frame.

[0025] The identification step is followed by a comparison step consisting of comparing the measured position of each reference point 13 to an expected position of the same reference point 13, in the same reference frame linked to the radar 6, each expected position being represented by a set of expected coordinates Bi, in this case B1, B2, B3, stored in a memory of device 1. Similarly, each set of expected coordinates Bi is, for example, composed of a distance and angular measurements in order to characterize the expected position of the reference point 13 in question relative to a reference location 13 positioned on the active face 7 of the radar 6. By expected position of a reference point 13, it is appropriate to understand the position that the reference point 13 in question should have in the absence of positioning or alignment errors and / or mounting backlash. Each set of measured coordinates Ai or expected coordinates Bi can, for example, be mathematically represented by a three-dimensional vector.

[0026] In the embodiment illustrated in [Fig.1], the reference points 13 correspond, for example, to three fixing points of the windshield washer motor 12.

[0027] Finally, the method includes a calibration step consisting of determining a repositioning matrix MR, shown schematically in [Fig. 2], which allows each set of measured coordinates Ai to be correlated with the corresponding set of expected coordinates Bi. The correlation between the sets of measured coordinates Ai and the sets of expected coordinates Bi is, for example, a mathematical operation consisting of a matrix multiplication of the form MR x Ai = Bi.

[0028] In order to avoid implementing the process according to the invention each time the device 1 is powered on, the parameters of the repositioning matrix MR are stored in a memory of the device 1.

[0029] When the radar 6 of the device 1 exhibits homogeneity of detection over its entire field of observation 8, that is to say when it maintains angles and distances over its entire field of observation 8, the repositioning matrix MR is representative of a translation and / or a rotation in the reference frame linked to the radar 6.

[0030] Once calibrated by implementing the method according to the invention, the repositioning matrix MR is used to correct the positions of points scanned by the radar 6. For this purpose, the control unit of the device 1 is also designed to transform the scanned coordinates Si of each scanned point into calibrated coordinates Ci using the repositioning matrix MR, for example, using the mathematical relationship MR x Si = Ci.

[0031] Thus, the method according to the invention offers an alternative to the manual calibration step previously used. The use of predetermined, distinct reference points 13 linked to the vehicle makes the method dependent solely on the vehicle and the installation of the radar 6. The device 1 is therefore able to correct alignment and / or mounting defects of the radar 6. The device 1 can optionally implement the calibration method during its initial commissioning. service and / or at predetermined time intervals. Device 1 is then always correctly calibrated, without operator intervention.

[0032] The invention is not limited to the embodiment of the obstacle detection device and the implementation of the calibration process described above, only by way of example, but other embodiments can be designed by a person skilled in the art without departing from the scope and extent of the present invention.

Claims

Demands

1. A method for calibrating an obstacle detection device (1) (4) mounted on an opening (2) of a motor vehicle, the device (1) being of the type comprising a radar (6) fixed to the vehicle, the method comprising an identification step consisting of using data from a radar scan (6) of its field of view (8) to determine the measured positions in the field of view, relative to a frame of reference linked to the radar (6), of a plurality of predetermined and distinct reference points (13) arranged on the vehicle, each measured position being represented by a set of measured coordinates (A1, A2, A3), the identification step being followed by a comparison step consisting of comparing the measured position of each reference point (13) to an expected position of the same reference point (13), in the same frame of reference linked to the radar (6),each expected position being represented by a set of expected coordinates (B1, B2, B3) stored in a memory of the device (1), the method comprising a calibration step consisting of determining a repositioning matrix (RM) allowing to correlate each set of measured coordinates (A1, A2, A3) to the corresponding set of expected coordinates (B1, B2, B3), characterized in that the identification step determines the measured positions of three reference points (13) forming a three-dimensional reference frame, the three reference points (13) corresponding to fixing points (9) of a windshield wiper motor (12).

2. Calibration method according to claim 1, characterized in that the parameters of the repositioning matrix (RM) are stored in a memory of the device (1).

3. Calibration method according to claim 1 or 2, characterized in that the repositioning matrix (RM) is representative of a translation and / or a rotation in the reference frame linked to the radar (6).

4. An obstacle detection device (1) designed to be fixed to a motorized opening (2) of a motor vehicle, the device (1) comprising a radar (6) capable of detecting an obstacle within its field of view (8), the device (1) further comprising at least one memory designed to store a plurality of sets of expected coordinates (B1, B2, B3), the device (1) comprising a control unit designed to perform the method according to any one of the claims 1 to 3 in order to determine a repositioning matrix (RM).

5. Detection device (1) according to claim 4, characterized in that the control unit is designed to transform the coordinates of each point measured in the observation field (8) of the radar (6) into calibrated coordinates using the repositioning matrix.

6. Device (1) according to claim 4 or 5, characterized in that it is designed to be fixed to a rear flap (3) of a motor vehicle.

7. A detection device (1) according to claim 6, characterized in that at least

8. Vehicle comprising at least one device (1) according to any one of claims 4 to 7.

Images