Patent Description:
When a driver of a long vehicle or a vehicle combination performs a reverse operation in the vicinity of an object (e.g. a loading dock or any other obstacle), it is hard to distinguish whether or not the driver is at a safe distance from the obstacle or object. Document <CIT> discloses a system and a method for avoiding collisions. Document <CIT> discloses a method for determining trailer information. In particular, if the object is not parallel to a back side of the vehicle, conventional sensors are unable to precisely measure the real closest distance along the reversing direction to the object. In such situations, the reversing maneuver mainly depends on the driver experiences and skills. Also a driving unit utilized in autonomous driving may draw wrong conclusions in such situations. Therefore, there is a demand for a system that is able to assist the driver or a driving unit during the reversing operation. At least some of the problems of the conventional device as described before are overcome by a device of claim <NUM>, a control unit of claim <NUM>, and a method according to claim <NUM>. The dependent claims refer to further advantageous realizations of the subject matters of the independent claims.

The present invention relates to reversing assistance device, according to independent claim <NUM>, for a vehicle. The vehicle comprises a radar unit mounted on a rear of the vehicle which is configured to provide distance information to an object that is fully or partially behind the vehicle when approaching the object under an approaching angle α (which may neither be zero nor <NUM>°).

The term "object" can be understood as an object partially or fully located behind the vehicle. The object can further be understood as any obstacle on the reversing way or direction such as a loading dock, a house, a bump, a wall, a column, a pollard, another vehicle etc. The object herein may be particularly an object that is neither fully parallel to the reversing direction nor fully perpendicular to the reversing direction. The object may have any height (e.g. <NUM> or higher, <NUM> or higher).

The vehicle may, in particular, be a commercial vehicle such as a long-haul transport vehicle, a trailer, a towing vehicle, a vehicle combination etc..

The shortest longitudinal distance C is a distance between points where the vehicle and the object hit each other when the reversing continuous. Typically, it a corner of the rear of the vehicle and a point (or line) on the object. Considering that the vehicle is approaching the object under an angle α, it should be appreciated that a closest distance R measured by the radar unit may, in general, be greater than the shortest longitudinal distance C.

The radar unit may comprise at least one of the following: an antenna array, a phased array antenna, a MIMO Radar or any other means to enable the radar unit to measure not only the closest distance(s) R, but also the angle α or longitudinal and/or lateral position information from the radar unit to reflection point(s) of the return signals. The radar unit may also comprise multiple radar elements, which may be placed at different locations, each comprising a transmitter and a receiver so that multiple distances can measured. In other words, the exemplary radar unit may include multiple transmitters and receivers to enable an angular resolution for the received signals.

The evaluation unit is configured to determine the parameters listed below, and to transmit to other systems at least one of:.

The other systems may include another control unit in the vehicle or a driving unit and may issue, upon receipt of one or more of the above information, a warning or may initiate other actions (e.g. a braking action).

Therefore, although the radar unit may be mounted at a central position or a middle position, this is not necessary. The radar unit may be mounted at any position at the rear of the vehicle and the evaluation unit may take into account the distance (offset) of the radar unit from a corner or from a middle line of the vehicle rear. Hence, according to embodiments, the evaluation unit is configured to compensate any offset in the position of the radar unit. The corresponding information about the mounting position may be stored in the radar unit or in the evaluation unit or may be obtained from any storage device in the vehicle.

The vehicle may be operated by a driver or by a driving unit and, optionally, the evaluation unit is further configured to issue a signal to the driver or the driving unit, in case the determined shortest longitudinal distance C, is shorter than a threshold (e.g. <NUM> meters, <NUM> meter or less).

Optionally, the evaluation unit is configured to issue an alert signal triggering at least one of the following: an acoustic signal, a visual indicator in a cabin or at the vehicle visible for the driver through the side window or side mirrors, a transmission of a warning to other systems (e.g. a vehicle electronic control unit).

The vehicle may further comprise at least one further sensor mounted on a side of the vehicle and configured to detect the object at the side of the vehicle. If so, the evaluation unit may further be configured to receive a detection signal of the further sensor as a confirmation of a presence of the (angled) object.

Optionally, the evaluation unit is configured to be placed in an idle state and an activated state. The reversing support function may be provided, e.g. only, in the activated state which is triggered by (an upcoming) engaging the reverse gear by a driver or a driving unit. The driving unit may e.g. implement a highly automated driving (HAD). Therefore, a driver may or may not be present in the vehicle during driving. The driving unit may control the reversing operation without any input from the driver (which may act only as a supervisor). The initiated or upcoming reverse gear can be sensed by corresponding sensors.

Further embodiments relate to an electronic control unit (ECU) configured to control a function of the vehicle. The ECU may include a reverse assistance device as defined before. Optionally the ECU is one of the following: a brake control unit, a light control unit, a vehicle electronic control unit, a radar control unit (i.e. the reversing assistance device may be implemented in the radar unit itself), a telematic unit.

Further embodiments relate to a vehicle with a radar unit and a reverse assistance device or an ECU as described before. Optionally, the vehicle includes a tractor and a trailer, and the radar unit is mounted at the rear of the trailer. The vehicle here may be understood as any type of motor vehicle used for transporting goods or paying passengers, e.g. long-haul transport vehicles, trucks, bus, etc..

Further embodiments relate to a method for assisting a vehicle while reversing, according to independent claim <NUM>.

The present invention further relates to a computer-readable storage device having software instructions stored thereon, designed to carry out, when executed on a data processor, the method for assisting a vehicle when reversing as defined before. Thus, the method may also be implemented in software or as a computer program product. The order of steps can be arbitrary as long as the desired effect is achieved. Embodiments of the present invention can, in particular, be implemented in an ECU, e.g. by software or a software module. Therefore, embodiments relate also to a computer program having a program code for performing the method, when the computer program is executed on a processor.

Some examples of the systems and/or methods will be described in the following by way of examples only, and with respect to the accompanying figures, in which:.

<FIG> depicts a reversing assistance device <NUM> for a vehicle <NUM> according to embodiments. The vehicle <NUM> comprises a radar unit <NUM> mounted on a rear <NUM> of the vehicle <NUM>. The vehicle <NUM> is approaching an object <NUM> that is partially or fully behind the vehicle <NUM> with a speed/direction V along a reversing direction y. It is understood that the device may also be installed on the trailer, not necessarily on the tractor, or in any other control or HAD unit present in the vehicle <NUM>.

The radar unit <NUM> may be mounted on the rear <NUM> at any position, e.g. spaced from a middle by an offset g. For example, a different radar unit <NUM>' can be placed at a different position (see dashed device <NUM>'). The radar unit <NUM> transmits radar signals (continuous or pulsed) which are reflected at the object <NUM> and return subsequently to the radar unit <NUM>. The closest distance R from the radar unit <NUM> to the object <NUM> represents the propagation path of the first return signal, which can be easily detected by the radar unit <NUM>. The line of the closest distance R should have a rectangular angle with a surface plane of the object <NUM>. The radar unit <NUM> will, in general, receive multiple return signals from additional reflections, which encode information about the geometry of the object <NUM>.

According to embodiments, the radar unit <NUM> is configured to provide an angular resolution in that it provides information enabling a determination of an approaching angle α. For this, the radar unit <NUM> may include an antenna array or multiple transmitter and receivers that allow to measure the angle α for the first and probably strongest return signal. For example, if the radar unit <NUM> comprises a first radar unit <NUM> and a second radar unit <NUM>', two shortest distances R1, R2 can be determined, from where the approaching angle α can be calculated as <MAT>, wherein the closest distance R1 is measured by the radar unit <NUM>, the closest distance R2 is measured by another radar unit <NUM>' and g is the distance between both radar units <NUM>, <NUM>'. According to the present notation, the angle α is greater than <NUM> and smaller than <NUM> degrees (<NUM>° > α > <NUM>).

Since the shortest or closest distance R may always be greater than zero - even if the vehicle <NUM> hits the object <NUM> - this information is not reliable. Accordingly, the reversing assistance device <NUM> comprises an evaluation unit <NUM> that provides a reversing function by obtaining the distance information R, R1, R2, α from the radar unit <NUM> and determines a shortest longitudinal distance C. This shortest longitudinal distance C is the distance measured along the reversing direction y from a corner <NUM> of the vehicle rear <NUM> to the object <NUM>. If the approaching angle α is smaller than <NUM>°, left-hand corner <NUM> (as shown in <FIG>) will be taken, and if the approaching angle α is larger than <NUM>° a right-hand corner (opposite corner of the corner <NUM> in <FIG>) will be taken. In any case, the determination of the shortest longitudinal distance C can be done from the corner that will hit the object when the vehicle <NUM> keeps reversing.

<FIG> depicts another embodiment for the reversing assistance device <NUM>, where the vehicle <NUM> is reversing along a reversing direction y and the radar unit <NUM> is mounted at the vehicle rear <NUM> at a center position (viewed in the depicted top view). Here, the vehicle <NUM> comprises a trailer <NUM>, a sensor device <NUM> mounted on the side of the vehicle <NUM>, and the radar unit <NUM> mounted on the trailer <NUM>. The sensor device <NUM> may be a camera, another radar or any other sensor that is able to capture information from the surrounding which is mounted anywhere at the side of the trailer or on towing vehicle (e.g. at a mirror).

The radar unit <NUM> is configured to sense objects behind the vehicle <NUM> in its coverage area <NUM>. The coverage area <NUM> includes an area that is strictly behind the vehicle <NUM> which may be covered only by the radar unit <NUM>, and an area that is behind the vehicle <NUM>, but which can be covered by the sensor device <NUM>, too. The sensor device <NUM> is configured to sense objects beside the vehicle <NUM> in its coverage area <NUM>. This coverage area <NUM> includes an area that is strictly beside the vehicle <NUM> and can be sensed only by the sensor device <NUM> (not by the radar unit <NUM>). In an overlapping area of both coverage areas objects can be sensed by the sensor device <NUM> and by the radar unit <NUM>.

<FIG> further shows a reflection point <NUM> on the object <NUM> that reflects radar signals emitted from radar unit <NUM> on the shortest path back to the radar unit <NUM>(corresponding to the closest distance R).

Next, further details will be described of how, according to embodiments, the evaluation unit <NUM> may determine the shortest longitudinal distance C to thus enable a compensation of a non-rectangular approaching angle α.

<FIG> illustrates several distances that may be used by embodiments to determine the shortest longitudinal distance C form the exemplary left corner <NUM> of the vehicle <NUM> to the object <NUM> along the reversing direction y. It should be understood, the reversing direction could also be curved for which the shortest longitudinal distance C can still be calculated. However, to keep the calculation simple, it is assumed that the vehicle <NUM> reverses along a straight line (y-direction).

According to embodiments, the evaluation unit <NUM> receives from the radar unit <NUM> the closest distance R and the approaching angle α to the object <NUM>. The determination may be based on multiple distances or a point cloud or even an image of the object <NUM> or any other information from where the closest distance R and the approaching angle α can be derived. The closest distance R is measured to the reflection point <NUM>, which in this embodiment is not strictly behind the vehicle <NUM>.

A distance between the corner <NUM> and the radar unit <NUM> may be known and will be denoted by "a". The evaluation unit <NUM> may further be configured to determine a reflection distance F. The reflection or longitudinal distance F is a distance measured between the vehicle rear <NUM> and the reflection point <NUM> and is calculated as: <MAT>.

The evaluation unit <NUM> is further configured to calculate a lateral distance "b" between the radar unit <NUM> and the reflection point <NUM> by: <MAT>.

Furthermore, the evaluation unit <NUM> is configured to determine the shortest longitudinal distance C between the corner <NUM> and the object <NUM> along the reversing direction y of the vehicle <NUM> as: <MAT> wherein "b - a" is denoted in <FIG> by "d".

Furthermore, it is apparent that this calculation applies in the case where the approaching angle α is larger than <NUM>°, in which case not the depicted distance "a", but the distance from the radar unit <NUM> to the opposite corner will be used in the calculation. If the radar unit <NUM> is in the middle, both distances to the corners will be equal and the calculation does not change.

Furthermore, according to embodiments, the evaluation unit <NUM> may be able to compensate any offset in the position of the radar unit <NUM> from a default or reference position (e.g. from a middle line of the vehicle <NUM>). The corresponding information about the mounting position may be stored in the radar unit <NUM> or in the evaluation unit <NUM> or may be obtained from any storage device in the vehicle <NUM>. It is understood that the mounting position of the radar unit <NUM> can be arbitrary, i.e. the offset may relate to any spatial direction. According to embodiments, this information is known (e.g. there is a predetermined mounting position) and will be taken into account when determining the shortest longitudinal distances C. Hence, the offset can be compensated.

<FIG> depicts an exemplary vehicle <NUM> reversing toward the object <NUM> under a larger approaching angle α so that the reflection point <NUM> is here strictly behind the vehicle <NUM>. All other features are implemented as in the embodiments described before. Therefore, the known distance between the corner <NUM> and the radar unit <NUM> can again be denoted by "a" and the evaluation unit <NUM> may be configured to determine a reflection distance F as a longitudinal distance between the rear <NUM> and the reflection point <NUM> and calculated according to equation (<NUM>). It may further be configured to determine a lateral distance b according to equation (<NUM>) and to determine the shortest longitudinal distance C by equation (<NUM>), wherein the value: e = b-a is now negative.

From the situation depicted in <FIG> it is further apparent the value of the closest distance R obtained from the radar unit <NUM> differs from the actual shortest longitudinal distance C (it is longer). There is an immediate risk of collision when the driver or the driving unit would rely on the information.

The vehicle <NUM> may also include a driving unit that implements a highly automated driving (HAD). Therefore, a driver may or may not be present in the vehicle during driving and the driving unit may control the reversing operation without any input from the driver (who may act only as a supervisor). Hence, the reversing assistance device <NUM> helps not only a driver of the vehicle <NUM>, but may also assist a driving unit, based on the shortest longitudinal distance information C information, to more accurately and reliably assess of the actual situation.

<FIG> depicts a schematic diagram of different units of a vehicle <NUM> connected to each other via a communication link such as a controller area network, CAN bus <NUM>, or ethernet or another data communication infrastructure. The vehicle <NUM> may comprise various control units such as a vehicle control unit <NUM> or a central control unit, a light control unit <NUM> to control the light indicators, a brake control unit <NUM>, and a control unit integrated in the radar unit <NUM>. The evaluation unit <NUM> can be in communication with all these control units via the exemplary CAN bus <NUM> and/or via wireless or via any radio communication to exchange data.

However, according to embodiments, the evaluation unit <NUM> may be integrated in one these control units, i.e. in the radar unit <NUM> or in the braking unit <NUM>, or in the light control unit <NUM> or in the central unit <NUM>. In particular, integration may mean that no additional component has to be added to the vehicle. In other words, after integration of the evaluation unit <NUM> into a given control unit, both components cannot be separated from each other. All functions of the evaluation unit <NUM> can be implemented into the given control unit by installing respective software.

Therefore, embodiments relate also to an electronic control unit, ECU, including the reversing assistance device <NUM>. The electronic control unit ECU is then configured to control a dedicated function (e.g. braking, lights) of the vehicle <NUM> and, in addition, the reversing assistance. For example, if the reversing assistance device <NUM> is integrated into the brake control unit <NUM>, it will control the vehicle braking as well as provides the reversing function.

The evaluation unit <NUM> may further be configured to be placed in an idle state and an activated state. The evaluation unit <NUM> may provide the reversing support function only in the activated state. The activated state may be triggered by engaging a reverse gear by the driver and/or by a driving unit. Similarly, the evaluation unit <NUM> may be triggered to be in the idle state when no reverse gear is engaged (by engaging a forward gear and/or parking gear) by the driver and/or driving unit.

The evaluation unit <NUM> may further be configured to determine a speed V of the vehicle <NUM> and an acceleration of the vehicle <NUM>. The evaluation unit <NUM> may be further configured to be in communication with internal sensors of the vehicle to obtain the speed V of the vehicle and the acceleration of the vehicle <NUM>. Therefore, the actual reversing speed may be taken into account, for example, for a warning of an imminent collision.

For example, according to the embodiments, the evaluation unit <NUM> is configured to issue a signal to the driver or the driving unit, in case the determined shortest longitudinal distance C is shorter than a predefined threshold (e.g. <NUM> meters, <NUM> meter or less). The predefined threshold may be calculated by the evaluation unit <NUM> based on a speed V of the vehicle <NUM> and/or distance information obtained from the radar unit <NUM>. The predefined threshold may be obtained from a control unit of the vehicle <NUM>.

According to the embodiments, the issued signal by the evaluation unit <NUM> may trigger at least one of the following: an acoustic signal, a blinking marker, a visual indicator in a cabin or visible through a window or mirror, an (electric) transmission of a warning to other systems (any vehicle ECU). The issued signal may have different intensity (e.g. loudness of the acoustic signal or the frequency of the blinking end-outline marker etc.) in relation with the value of the shortest longitudinal distance C.

<FIG> depicts a flow diagram of a method <NUM>, for assisting a vehicle <NUM> reversing. The vehicle <NUM> comprising the at least one radar unit <NUM> mounted on the rear <NUM> of the vehicle <NUM> and configured to provide distance information R, α when approaching an object <NUM> fully or partially behind the vehicle <NUM> under an approaching angle α. The method comprises the steps of:.

The method <NUM> may further comprise determining at least one of the following: a speed of the vehicle <NUM>, an acceleration of the vehicle <NUM>, the approaching angle α, a reflection distance F, a lateral distance b.

Claim 1:
A reversing assistance device (<NUM>) for a vehicle (<NUM>),
the vehicle (<NUM>) comprising a radar unit (<NUM>) mounted on a rear (<NUM>) of the vehicle (<NUM>) and configured to provide distance information (R, α) to an object (<NUM>) that is fully or partially behind the vehicle (<NUM>) when approaching the object (<NUM>) under an approaching angle α,
characterized by:
an evaluation unit (<NUM>) configured to provide a reversing support function by:
- obtaining from the radar unit (<NUM>) the distance information (R, α) to the object (<NUM>), wherein the radar unit is configured to measure a closest distance R and an approaching angle α from the radar unit to a reflection point (<NUM>) of a first return signal;
- determining, based on the distance information (R, α), a shortest longitudinal distance C between a corner (<NUM>) of the rear (<NUM>) of the vehicle (<NUM>) and the object (<NUM>) along a reversing direction y of the vehicle (<NUM>); and
the evaluation unit (<NUM>) is further configured to determine:
- a longitudinal distance F between the rear (<NUM>) of the vehicle (<NUM>) and the reflection point (<NUM>) on the object (<NUM>) measured along reversing direction y, by using: F = R × sin α, wherein R is the closest distance R and α the approaching angle;
- the lateral distance b between the radar unit (<NUM>) and the reflection point (<NUM>) measured along a lateral direction x by using: b = R × cos α, wherein R is the closest distance and α is the approaching angle;
- the shortest longitudinal distance C, by using: C = F + (b-a) × b/F, wherein "a" is a distance from the radar unit (<NUM>) to a rear corner (<NUM>) of the vehicle (<NUM>),
wherein the closest distance R from the radar unit (<NUM>) to the object (<NUM>) represents the propagation path of the first return signal, and the line of the closest distance R has a rectangular angle with a surface plane of the object (<NUM>).