SENSOR DEVICE FOR MEASURING MOTION OF VEHICLE AND METHOD OF OPERATING THE SENSOR DEVICE

Abstract

A sensor device for measuring a motion of a vehicle includes a light source for radiating light on a region on a ground below the vehicle in temporal intervals and to produce a spot of increased temperature; a heat detection unit, which is mountable at an underside of the vehicle for detecting a position of the spot on the ground at the temporal intervals; and a control unit for receiving data about a measured time of the spot and the position of the spot from the heat detection unit and to estimate a change of the position of the spot in vehicle coordinates.

Claims

1. A sensor device for measuring a motion of a vehicle, comprising: a light source which is mountable on an underside of the vehicle, wherein the light source is configured to radiate light on a region on a ground below the vehicle in temporal intervals and thereby to produce a spot of increased temperature relative to a surrounding region of the spot on the ground; a heat detection unit, which is mountable at the underside of the vehicle and which is configured to detect a position of the spot on the ground at the temporal intervals; and a control unit which is connected to the heat detection unit and which is configured to receive data about a measured time of the spot and the position of the spot from the heat detection unit and to estimate a change of the position of the spot in vehicle coordinates.

2. The sensor device according to claim 1, wherein the control unit is configured to calculate a side slip angle or a speed vector of the vehicle from two consecutively measured spots at different times and compare it to a previous state.

3. The sensor device according to claim 1, wherein the light source is configured to radiate the light to the spot at a first moment and at a second moment which are shifted in time, wherein a direction of radiating the light from the vehicle is constant with regard to the vehicle.

4. The sensor device according to claim 1, wherein the light source is a pulsed laser.

5. The sensor device according to claim 4, wherein the laser has a pulse rate of 200 Hz.

6. The sensor device according to claim 1, wherein the heat detection unit comprises a thermal camera, having a constant field of view relative to the vehicle.

7. The sensor device according to claim 1, wherein the heat detection unit is configured to record the position of the spot at the temporal intervals at which the light of the light source is radiated to the spot.

8. The sensor device according to claim 1, wherein the sensor device comprises a storage device to which data from the heat detection unit is saved and wherein the control unit is connected to the storage device and configured to post-process the data stored in the storage device over time.

9. A method for operating a sensor device for measuring a motion of a vehicle, comprising the steps of: providing a sensor device, the sensor device comprising: a light source which is mountable on an underside of the vehicle; a heat detection unit, which is mountable at the underside of the vehicle; and a control unit which is connected to the heat detection unit and which is configured to receive data about a measured time of the spot and the position of the spot from the heat detection unit and to estimate a change of the position of the spot in vehicle coordinates; setting a counter for light radiation from the light source and temporal measurement at the heat detection unit to zero; radiating light to a spot by the light source and detecting a position of the spot on a ground by the heat detection unit at consecutive moments shifted in time according to a predetermined temporal interval and providing data of the spot position; processing the data of the spot position by the control unit and estimate a change of the position of the spot in vehicle coordinates.

10. The method according to claim 9, wherein the control unit calculates a side slip angle or a speed vector of the vehicle from two consecutively measured spots at different times and compares it to a previous state.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] For a more complete understanding of the present disclosure and advantages thereof, reference is made to the following description taken in conjunction with the accompanying drawings. The disclosure is explained in more detail below using exemplary embodiments, which are specified in the schematic figures, in which:

[0045] FIG. 1 shows a view of a vehicle defining velocity components and a side slip angle according to an embodiment of the disclosure;

[0046] FIG. 2 shows a sensor device for monitoring a spot on the ground for detection of the motion of the vehicle according to an embodiment of the disclosure;

[0047] FIG. 3 shows a relation between measured spot positions and the motion parameters of the vehicle; and

[0048] FIG. 4 shows a flowchart of a method according to an embodiment of the disclosure.

[0049] Unless indicated otherwise, like reference signs to the figures indicate like elements.

DETAILED DESCRIPTION

[0050] It is understood that the term “vehicle” or “vehicular” or other similar term as used herein is inclusive of motor vehicles in general such as passenger automobiles including sports utility vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g. fuels derived from resources other than petroleum). As referred to herein, a hybrid vehicle is a vehicle that has two or more sources of power, for example, both gasoline-powered and electric-powered vehicles.

[0051] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Throughout the specification, unless explicitly described to the contrary, the word “comprise” and variations such as “comprises” or “comprising” will be understood to imply the inclusion of stated elements but not the exclusion of any other elements. In addition, the terms “unit”, “-er”, “-or”, and “module” described in the specification mean units for processing at least one function and operation, and can be implemented by hardware components or software components and combinations thereof.

[0052] Further, the control logic of the present disclosure may be embodied as non-transitory computer readable media on a computer readable medium containing executable program instructions executed by a processor, controller or the like. Examples of computer readable media include, but are not limited to, ROM, RAM, compact disc (CD)-ROMs, magnetic tapes, floppy disks, flash drives, smart cards and optical data storage devices. The computer readable medium can also be distributed in network coupled computer systems so that the computer readable media is stored and executed in a distributed fashion, e.g., by a telematics server or a Controller Area Network (CAN).

[0053] FIG. 1 exemplarily shows a view on a vehicle defining velocity components and a side slip angle according to an embodiment of the disclosure.

[0054] FIG. 1 shows a top view of the vehicle V and a possible motion. The wheels of the vehicle can be positioned at a particular steering angle which can result in a side slip angle, which can represent a change in the direction of an initial motion after the beginning of a measurement. From the measured data it can be possible to conduct a post-processing and a side slip angle β and ground velocity components vx and vy can be estimated. These values can be delivered to assistance systems in the vehicle.

[0055] FIG. 2 exemplarily shows a sensor device for monitoring a spot on the ground for detection of the motion of the vehicle according to an embodiment of the disclosure.

[0056] The sensor device 10 for measuring a motion of a vehicle V comprises a light source LS which is mounted on an underside U of the vehicle V, and wherein the light source LS is configured to radiate light on a region on a ground (e.g., soil) below the vehicle in temporal intervals and to produce a spot of increased temperature relative to a surrounding region of the spot on the ground; a heat detection unit DU, which is mountable at the underside of the vehicle and which is configured to detect the position of the spot on the ground at temporal intervals; and a control unit CU which is connected to the heat detection unit DU and which is configured to receive data about the measured time of the spot and the position of the spot from the heat detection unit and to estimate a change of the position of the spot in vehicle coordinates. The light source can be mounted close to the heat detection unit, for example, directly adjacent to it laterally at the underside of the vehicle. The field of view FOV of the heat detection unit DU can stay constant and have an extend XFOv in one or both of the planar coordinates of the ground in vehicle coordinates. The XFOv can be large enough such that at the given rate of spot radiation, for example, at 200 Hz, at least two consecutively produced spots Ei−1 and Ei can be within the field of view FOV in this extend, having a distance Di between them.

[0057] The control unit CU can be configured to calculate a side slip angle and a speed vector (vx, vy) of the vehicle from two consecutively measured spots Ei−1 and Ei at two consecutive moments in time ti−1 and ti. The position of the spot Ei is compared relative to the vehicle and to the position of the spot at the previous time moment ti−1 and compare it to a previous state at ti−1. The light source LS is configured to radiate the light to the spot at a first moment ti−1 and at a second moment ti which are shifted in time, wherein a direction of radiating the light to the spot from the vehicle is constant with regard to the vehicle. The light source can be a pulsed laser, for example, having a frequency of producing a spot of 200 Hz. The heat detection unit DU may comprise a thermal camera, having a constant field of view relative to the vehicle V.

[0058] The sensor device 10 may comprise a storage device SD, which can be mounted in or at the vehicle or remote to it and to which data from the heat detection unit DU may be saved and wherein the control unit CU can be connected to the storage device SD and configured to post-process the data stored in the storage device SD over time.

[0059] FIG. 3 exemplarily shows a relation between measured spot positions and the motion parameters of the vehicle.

[0060] The motion parameters for the vehicle V are shown in a side view in FIG. 2 and in a top view in FIG. 3. The spot can be produced on the ground at two consecutive times ti−1 and ti producing the corresponding spots Ei−1 and Ei which can be within the measured field of view FOV at the applied frequency of radiation and measurement. The second spot Ei can be a total distance Di away from the position of the previous spot Ei−1. The total distance can be split into deviations in vehicle coordinates dXi and dYi which have the side slip angle β between them.

[0061] The principle of consecutive time moments can be used also for further moments as t1=t0+1/f, f being the pulse frequency. Therefore, the measurement of the spot position can be repeated N−1 more times until end of test with N pictures of current and previous vehicle positions. In this sense the side slip angle at the pair of moments is βi=tan−1(dYi/dXi).

[0062] For each of the N pictures taken by the heat detection device coordinates of Ei−1 and Ei can be measured in vehicle reference frame and then components of relative displacement can be calculated dXi=Xi−Xi−1 and dYi=Yi−Yi−1.

[0063] The vehicle can have an initial reference position at ti−1 and an already changed position and orientation at ti.

[0064] Every particular position can be expressed in the corresponding coordinates (vehicle coordinates), for example, Ei=(Xi, Yi) and Ei−1=(Xi−1, Yi−1) wherein Di=(Xi−Xi−1, Yi−Yi−1). For each change in position the particular side slip angle can be calculated.

[0065] A counter for data measurement and post processing can be set to zero, in other words start at a first moment. This corresponds to resetting a calculation loop for tracking several positions.

[0066] A loop for measurements and post data processing can be completed as follows.

[0067] At t.sub.i+1=i×0.005 s, a picture of the spot can be imported to the control unit. The picture of the ground with the two chronogically successive heated spots (markers) in the frame is taken or imported.

[0068] Further, it is possible therefrom to detect and uniquely label both markers as E.sub.i at t.sub.i and E.sub.i+1 at t.sub.i+1.

[0069] Both markers can be geometrically identified and tagged with a unique label. An identification can be based on a characterization of a heat contour with a specific threshold value of the spot, thereby labelling is linked to the time step when the marker is detected on the ground.

[0070] Further, X and Y coordinates for E.sub.i and E.sub.i+1 can be measured, the coordinates of the center of each marker can be measured on the image in both dimensions X and Y.

[0071] Further, it is possible to calculate β for marker E.sub.i and the angle between both markers can be calculated by formula β=tan.sup.−1 (Y/X).

[0072] The resulting positions, angle, velocity components can be stored in the storage, for example, as rows in a table.

[0073] Each value can be stored in an exportable file format sorted by time. The values can be used for online processing or later for data analysis.

[0074] An increment i by 1 can be completed and the counter can be increased by 1, being a step to move on to the next image.

[0075] If there is already any further picture detected at the loop can return to the step of import a picture at ti+1. If there is no new picture detected, then the post processing can be stopped. Otherwise the loop starts again for the next time step.

[0076] FIG. 4 exemplarily shows a flowchart of a method according to an embodiment of the disclosure.

[0077] The method for operating a sensor device for measuring a motion of a vehicle comprises the step of providing S1 a sensor device according to the first aspect of the disclosure. The method further comprises the step of setting S2 a counter for light radiation from the light source and temporal measurement at the heat detection unit to zero; radiating light S3 to a spot by the light source and detecting S4 a position of the spot on a ground by the heat detection unit at consecutive moments shifted in time according to a predetermined temporal interval and providing data of the spot position. The method further comprises the step of processing S5 the data of the spot position by the control unit and estimate a change of the position of the spot in vehicle coordinates.

[0078] The disclosure has been described in detail referring to exemplary embodiments. However, it will be appreciated by those of ordinary skill in the art that modifications to these embodiments may be made without deviating from the principles and central ideas of the disclosure, the scope of the disclosure defined in the claims, and equivalents thereto.