GB2481324A

GB2481324A - Object detection and motion evaluation method for identifying parking space

Info

Publication number: GB2481324A
Application number: GB1110265.4A
Authority: GB
Inventors: Volker Niemz
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2010-06-17
Filing date: 2011-06-16
Publication date: 2011-12-21
Anticipated expiration: 2031-06-16
Also published as: GB2481324B; FR2961465A1; DE102010030213B4; GB201110265D0; DE102010030213A1; ITMI20111074A1; CN102310857A; FR2961465B1

Abstract

A parking assistance system provides a method of identifying a transverse parking space 32. The method also supports parking in the parking space 32. For this purpose, a travel motion of a motor vehicle 10 is evaluated by means of the following method steps: The travel motion is evaluated for straight travel and in particular for portions (44 see fig 2) during which the yaw angle of the motor vehicle 10 remains constant. At least one edge 70, 72 or one corner of a first object 34 delimiting the transverse parking space 32 is detected, and an edge 70, 72 or a corner of a second object 36 delimiting the transverse parking space 32 is detected. Thus, accurate parking space alignment can be determined in advance.

Description

Description Title

Parking assistance system for transverse parking spaces

Prior art

DE 10 2008 001 648 Al relates to a driver assistance method for moving a motor vehicle, and to a driver assistance device. The method serves, in particular, to prevent collisions through the use of at least one first sensor system that, in a first sensing region, provides first items of obstacle information for obstacle information for the driver of the motor vehicle. The driver assistance system comprises at least one second sensor system, which, in a second sensing region that is at an angle of > Q0 in relation to the first sensing region, provides further, second items of obstacle information, even if the obstacle is no longer present in the second sensing region. The first and the second items of obstacle information are combined in such a way that sensing errors of the sensor systems are corrected and updated obstacle information can be used.

DE 10 2008 002 598 Al relates to a device for semi-autonomous support of the steering motion of a vehicle.

The device comprises support means for providing items of information concerning steering positions of a vehicle steering and items of information concerning a distance travelled in a vehicle travel. A desired path, learned-in through a learning travel, for a defined environment is stored in a computer unit. The support means are designed in such a way that the desired path can be used upon the p vehicle attaining a specified position in the defined environment, and the driver is supported in guiding the vehicle along the desired path.

DE 10 2008 004 633 Al relates to a method and a device for identifying and/or gauging a parking space. According to the method, three-dimensional data of an environment of the vehicle is acquired. Objects in the environment of the vehicle are then classified into objects that delimit parking spaces and objects that do not delimit parking spaces.

Driver assistance systems serve in general to support the driver during the operation of parking in a longitudinal parking space or, also, in a transverse parking space, either through steering instructions or through an automatic control of the steering-wheel. In addition to longitudinal parking systems, transverse parking systems are also developed. In the case of future transverse parking systems, however, only reverse entry into the respective parking space is offered. This is due mainly to the fact that the reverse entry into the parking space is supported by the "ultrasound" measurement principle and the field of view. According to this method, only a few metres, such as, for example, 1 to 5 metres, are covered in the case of automotive applications. The sensors necessary for parking space detection are mounted in the front side part of a vehicle, on the left and on the right side, respectively.

Since the relevant parking space detection sensors are accommodated in the front region of the vehicle, it is essential for the sensor to pass the respective parking p space references before supported parking via an external system can be offered, since, at this point in time, only the relevant space is known to the system. The necessary data in this case is, on the one hand, the length and depth of the parking space and, on the other hand, the coordinates of the vehicle corners.

In the majority of cases, longitudinal parking spaces in which a driver parks in the forward direction are of such a size that the driver does not require any support. In contrast thereto, however, transverse parking spaces can be considerably smaller, irrespective of whether parking in the latter is to be in the forward or reverse direction.

In the case of both manoeuvres, i.e. forward parking and reverse parking, there is a hazard potential. Whereas, as is known from experience, parking in a majority of all longitudinal parking spaces is effected by reverse parking, parking in transverse parking spaces is effected both by forward and by reverse parking, depending on the situation and the country. For Europe, at least, it is the case that the majority of drivers park in a transverse parking space in the forward direction.

Systems that detect transverse parking spaces are usually provided with a parking space search routine, which detects a free, unoccupied parking space as the vehicle travels past along a row of vehicles. The parking guidance is then activated. After the system has found a suitable parking space, it is then up to the driver to activate the parking system, which proposes guided parking.

During the search for a parking space, only the front contours of the vehicles can be sensed, since the range of view of the systems that gauge parking spaces is only 4 to metres. Furthermore, there is the problem that the lateral vehicle contours cannot be gauged, since the ultrasound waves reflect away. Owing to the said system limitations, a sufficiently accurate parking space alignment must be determined in advance.

Summary of the invention

It is proposed according to the invention to determine, during the search for a suitable parking space, in particular a transverse parking space, in which the front contours of vehicles can be sensed, an initial alignment of the parking space, perpendicular to the drive-past direction, between the two objects that delimit the parking spaces. The initial alignment of the parking space, perpendicular to the drive-past direction, depends, however, on the travel motion, which is defined individually by the driver. In particular, the possibility exists for the driver to swing out to the left in the case of a transverse parking space located on the right, in order to achieve a favourable parking position. If the initially determined alignment is too remote from the reality, however, which can have its origin in a driving manoeuvre of a steering motion by the driver, these errors cannot be corrected with sufficient accuracy, even with regauging methods. For this reason it is proposed, according to the invention, to include the driver behaviour in the determination of the parking space alignment, since only in this way can it be ensured that a parking space alignment is achieved that corresponds to the actual alignment. According to the invention, use is made of the fact that the driver wishing to park in a transverse parking space always moves on a straight course for a certain period of time. This means that, within this period of time, the yaw angle profile remains constant, i.e. a constant yaw angle region is obtained, in which the yaw rate change in °/s remains constant. This means that, during this time span in which there is no yaw angle change, the driver moves straight ahead and, consequently, an initial alignment of the parking space, perpendicular to the drive-past direction, is obtained.

During the parking space search, in particular the search for a transverse parking space, the travel motion over a plurality of metres is stored. After an appropriate parking space situation has been identified, the alignment of the parking space can then be calculated on the basis of the passage of the constant yaw angle region of the stored data.

When this transverse parking space has been reached and a target alignment, i.e. an alignment in relation to the parking space, has been effected, then, according to the solution proposed according to the invention, edges and corners of the objects that delimit the transverse parking space are detected. The driver steering the vehicle is supported in forward parking in a transverse parking space, which is a standard parking scenario, particularly in Europe. The basic principle follows substantially the following steps: There follows first a driver-controlled parking, or commencement of the parking operation by the driver without system support, without assistance from parking systems.

The parking system identifies a first corner of an object that delimits the parking space, and identifies a second vehicle edge. There is identified therefrom a driving manoeuvre that corresponds to forward parking in a transverse space. After this driving manoeuvre has been identified, support is offered to the driver steering this vehicle, after which -once this offer has been accepted -the parking system, or the driver assistance system, assumes the control and steering of the vehicle. First, the steering angle can be limited, such that a collision between a front left vehicle corner and an object delimiting the parking space is prevented and, if appropriate, a stop instruction is output, such that path planning, or the correction of a calculated path, can be effected, or an active control of the steering wheel is effected, and a gear change prompt can be given to the driver, in order to complete the parking operation successfully.

Whereas, at the start of the forward parking, it is the driver steering the motor vehicle who himself effects parking, up to a certain point, in a parking space, gauging of the overall surroundings of the transverse parking space is performed by a number of ultrasound sensors provided on the motor vehicle. In this case these are, in particular, side sensors, which are disposed in the region of the mudguards, and front sensors mounted at the front end of the vehicle, which sensors can be four or more ultrasound sensors.

If the transverse parking space is delimited by objects disposed almost in parallel, thus, for example, parked vehicles, the respective sides of these objects, and their corners, can be detected via the side sensors. The alignment can be calculated with sufficient precision from the point in time from which the side sensors receive a direct echo from the edges of the objects delimiting the parking space. As long as these signals are not yet present, first estimate windows for these signals are emitted. The approximate order is based, at the start of the parking operation, on the cross echo between adjacent sensors, i.e. a side sensor and a front sensor on both sides of the vehicle, and from the direct echo of the ultrasound sensors, in particular the side sensors.

Before the system evaluates the last data seen, the driving manoeuvre "forward parking in a transverse parking space" is first identified. This can be effected on the basis of identification of a travel motion, during which the actual driving manoeuvre is analysed, thus, for example, in respect of characteristic steering-wheel, speed and ultrasound warning distance profiles.

This method can be further refined and improved by means of a GE'S-based map analysis, in that knowledge relating to the current location and the probability of the occurrence of transverse/longitudinal parking spaces is deduced. The x metres covered, thus, for example, 3 to 5 metres of the "map" compiled by the ultrasound signals, can then be evaluated on the basis of the identified parking space situation. The width of the parking space and, accordingly, a sufficiently necessary target position in the centre between the two vehicles, or objects, that delimit the drive-out parking space, can then be calculated on the basis of corners and edges. The alignment in relation to the target point should be effected such that the rear of the vehicle is at an approximately equal lateral distance from the two objects, or vehicles, that delimit the transverse parking space.

After the drive assistance system has been activated in this respect, the current steering angle is then checked.

Should the latter result in a collision with an object delimiting the parking space, the steering angle must be varied. For this purpose, an instruction to this effect is given to the driver, or a moment is applied to the steering wheel, in order to give the driver feedback concerning the direction in which the steering wheel is to be moved and, if appropriate, an automatically effected intervention is made in the steering apparatus, optionally supported by special acoustic, optical or haptic warnings and indications.

If the driver does not follow the instructions to end the driving manoeuvre, first initiated by the driver, in the initial parking move, further reverse moves and forward moves can be offered to the driver steering the vehicle.

These moves can originate from a calculated path, or result from adjustment to the target variables.

The solution proposed according to the invention allows a more robust identification of the alignment, including that of longitudinal parking spaces without a kerb. The absence of a kerb means that there is no reference for the angular alignment of the parking space, since the reference point for a parallel alignment is absent. Currently, for this case, an alignment is defined either on the basis of the proper motion of certain reference points, or various boundary objects and their alignment are evaluated.

Whereas, in the first-mentioned case, there is a high dependence on the driving behaviour in the previously defined region, the solution proposed according to the invention allows a lack of association with a region, a search for a characterizing feature being effected instead.

In the second case, set out above, of an alignment to objects, the objects, for their part, may be incorrectly aligned, thus, for example, badly parked road users, and, in addition, it is only with difficulty that ultrasound can identify the object position of short objects.

Brief description of the drawings

The invention is described more fully in the following with reference to the drawings, wherein: Figure 1 shows the sensing of front contours of parking vehicles by a vehicle driving past, Figure 2 shows the yaw angle profile and the yaw rate profile plotted over a distance travelled by the vehicle, Figure 3 shows the travel motion of a vehicle, and a portion of the travel motion of the vehicle in which the yaw angle is constant, Figure 4 shows a turning vehicle that passes a transverse parking space, and shows a portion of the travel motion of the vehicle in which the yaw rate angle remains constant, p.- -10 -Figure 5 shows the representation of a vehicle having front sensors and side sensors and associated sensing regions, Figure 6 shows a manoeuvre for parking in a longitudinal parking space, and Figure 7 shows various stages of a manoeuvre for parking in a detected transverse parking space, along a parking path.

Embodiment variants The detection of a transverse parking space, and an operation of parking in the firstly detected transverse parking space, in one parking move, are described in the following with reference to the drawings.

It can be seen from the representation according to Figure 1 that a motor vehicle 10 passes a transverse parking space 32. It can be seen from the representation according to Figure 1 that the motor vehicle 10 has side sensors 26, in particular a first side sensor 28 and a second side sensor 30. The first side sensor 28 of the side sensors 26 sweeps over a sensing region 48 on the right side of the motor vehicle 10. It can be seen from the representation according to Figure 1 that the transverse parking space 32 is delimited by a first vehicle 34 and a second vehicle 36.

Figure 1 additionally shows that the first vehicle 34 comprises front sensors 16. The reference 50 denotes a reflected ultrasound that is emitted, for example, by the first side sensor 28 of the side sensors 26. I'

-11 -In a second travel situation, the first side sensor 28 of the motor vehicle 10 emits, within its sensing region 48, an ultrasound signal that is deflected, as a reflected ultrasound beam 50, on a body 52 of the second vehicle 36 arid that is no longer reflected back to the first side sensor 28 emitting the ultrasound signal. Figure 1 shows that lateral vehicle contours of the first vehicle 34 delimiting the transverse parking space 32 or of the second vehicle 36 delimiting the transverse parking space 32 cannot be sensed.

Figure 2 shows the profile of the yaw angle, or of the yaw rate, plotted over the distance travelled. Figure 2 shows that a yaw angle profile 40 or a yaw rate profile 42 has a plurality of portions over a distance travelled. The profile of the yaw rate in O/, or of the yaw angle profile (degrees over the distance travelled) comprises a region 44, in which the yaw angle is constant. Transverse parking spaces 32 -as represented in Figure 1 -generally extend perpendicularly in relation to the carriageway. The initial alignment of the transverse parking space 32 perpendicular to the drive-past direction could be determined, for example, between the two objects 34, 36 that delimit the transverse parking space 32. However, since the travel motion of the motor vehicle 10 is unknown and the driver could, for example, pull out to the left, as represented in Figure 3 -such that a more favourable parking position is achieved -this procedure involves high risk. If the initially determined alignment is too remote from the reality, i.e. the real position of the transverse parking space 32, this error can no longer be corrected with sufficient accuracy, even by means of a reguaging method, such that additional parking moves are required, -12 -unnecessarily. For this reason, following the solution proposed according to the invention, the driver behaviour is included in the choice of the initial identification of the alignment of the transverse parking space. It is only in this way that a suitable alignment of the transverse parking space 32, in particular perpendicular to the drive-past direction, is ensured.

The solution proposed according to the invention makes use of the fact that the driver wishing to park in a transverse parking space always moves on a straight course for a certain period of time while driving past this transverse parking space. This means that, during this portion (cf. representation according to Figure 2) distance 38 travelled, the yaw angle profile 42 remains constant within a region 44.

The travel motion over some metres is always stored during the parking space search. After an appropriate situation, with a transverse parking space 32, has been identified, the alignment of this transverse parking space 32 can then be calculated on the basis of the already stored data, using the constant component found therein, i.e., the region 44 having a constant yaw angle. The representation according to Figure 3 shows that, similarly to the representation in Figure 1, the transverse parking space 32 is delimited by the first vehicle 34 and by the second vehicle 36. In the course of the travel distance 38, the motor vehicle 10 passes the transverse parking space 32 in the drive-past direction. The travel distance 38 covered by the motor vehicle 10 senses the portion 44, represented in Figure 3, having a constant yaw angle, i.e. a purely straight-ahead travel. A parking alignment 46 extends - -13 - relative to the portion 44 having a constant yaw angle -exactly perpendicularly in relation to the latter.

Deviations from a straight travel course, which consequently have a non-constant yaw angle, since steering motions are required for turning off to the left or changing the direction of travel to the right, are represented by broken lines in the representation according to Figure 3.

It can be seen from the representation according to Figure 4 that the motor vehicle 10 travels through a right-hand bend and then passes a row of vehicles parked perpendicularly in relation to the direction of travel of the motor vehicle 10. Between the first vehicle 34 and the second vehicle 36 there is the transverse parking space 32.

As shown by the representation according to Figure 4, the motor vehicle, after completing the right-hand bend, traverses the region 44 having a constant yaw angle already identified in connection with Figure 3, i.e. a part of the travel motion 38 in which no steering stop is effected.

Consequently, a transverse parking space 32 detected during the drive-past extends substantially perpendicularly in relation to the drive-past direction of the vehicle. The parking alignment 46, which is determined within the portion 44 having a constant yaw angle, extends -since there is purely straight-ahead travel -exactly perpendicularly in relation to the portion of the travel distance 38 and to the portion 44 in which a there is a constant yaw angle.

Through the solution, proposed according to the invention, of detecting a transverse parking space 32 during a portion 44 of the travel motion 38 of the motor vehicle 10 in which -14 -the yaw angle remains constant, or the yaw rate in °/sec.

is 0, makes it possible to sense a parking alignment 46 that runs substantially perpendicularly in relation to the direction of travel of the motor vehicle 10. The solution proposed according to the invention takes account of the individual driving behaviour of the driver steering the motor vehicle 10.

Figure 5 shows the representation of a motor vehicle 10 having a group of front sensors and having side sensors.

It can be seen from the representation according to Figure that, in the front region of the motor vehicle 10, there are front sensors 16, which comprises a first sensor 18, a second sensor 20, a third sensor 22 and a fourth sensor.

Tie sensing regions of the sensors 18 to 24 are directed substantially forwards in relation to the motor vehicle 10.

Furthermore, according to the representation in Figure 5, the motor vehicle 10 comprises side sensors 26 that are disposed in the mudguard region, namely, a first side sensor 28 and a second sensor 30.

It can be seen from the representation according to Figure 6 how the motor vehicle 10, having the sensors, represented in Figure 5, that cover the side region and the front region of the motor vehicle 10 is moved into a longitudinal parking space 54. The longitudinal parking space 54 has a width 58 and a length 56. The longitudinal parking space 54 is delimited by a first vehicle 34 and by a second vehicle 36.

It can be seen from the representation according to Figure 7 how, after detection of a transverse parking space, parking can be effected -following the solution proposed according to the invention -in this parking space. The representation according to Figure 7 shows that, after detection of the transverse parking space 32, which is delimited by a first object, being a first vehicle 34 in the present case, and by a second object, i.e. by a second vehicle in the present case, a parking operation can be effected in one move along an initial parking path 60. As already described in connection with Figure 5, the motor vehicle 10 comprises front sensors 16, being the front sensors 18, 20, 22 and 24, and comprises the side sensors 26, being the first side sensor 28 and the second sensor 30. The first side sensor 28 forms a sensor pair with the first sensor 18 of the front sensors 16, while, on the left side of the motor vehicle 10, the second sensor 30 forms a further pair with the fourth sensor 24 of the front sensors 16. Upon acceptance of the parking assistance, the motor vehicle parks in the transverse parking space 32, along the parking path 60 into the parking space 32. The solution proposed according to the invention, after detection of the transverse parking space 32, edges 70 and 72, and corners El, E2, as well as a suitable steering-wheel angle limitation and gear change, are initiated. A manoeuvre for forward parking in a transverse parking space 32, as is usual, for example, among European drivers, is thereby supported.

Following the solution proposed according to the invention, a driver-controlled parking operation, or the start of a manoeuvre for parking in the detected transverse parking space 32, is first effected by the driver, without the support of a driver assistance system. The driver assistance system first identifies a first vehicle corner El of the first vehicle 34, and then identifies a second 4" -16 -vehicle edge 72 of the second vehicle 36, which delimits the transverse parking space 32. From the presence of this state, the driver assistance system identifies the driving manoeuvre "forward parking in a transverse parking space".

The driver of the motor vehicle 10 is then offered support, which the latter can reject or, also, can accept.

If the driver of the motor vehicle 10 accepts the request, the driver assistance system takes over the guiding of the vehicle along the parking path 60, as represented in Figure 7. The steering-wheel angle is first limited, such that a collision with a front left vehicle corner E2 of the second vehicle 36 delimiting the transverse parking space 32 is reliably prevented. Then, a stop instruction is given, and the parking path 16 is planned, or recalculated, or the steering wheel is actively controlled and the driver is provided with gear change prompts to enable the parking operation, i.e. parking successfully in the transverse parking space 32, to be completed successfully in one move.

While, at the start of the manoeuvre for parking in the transverse parking space 32, the driver himself effects parking, up to a certain point, in the transverse parking space 32, all ultrasound sensors 18, 20, 22, 24, and 28 and 30, gauge the surroundings of the transverse parking space 32. An "ultrasound map" of the surroundings of the transverse parking space 32 delimited by the objects 34 and 36 is thus produced.

Owing to the almost parallel disposition of the two objects 34 and 36, the respective sides 70 and 72, and the corners El and E2 of the objects 34 and 32 can be detected by means -17 -of the sensor pairs 18, 28 and 24, 30, respectively, of their assigned sensing regions. From the point in time at which the side sensors 28 and 30 on both sides of the motor vehicle 10 receive a direct echo from the edges 70 and 72, respectively, of the objects 34, 36, the alignment can be calculated with a sufficient accuracy. Beforehand, first estimates are made for the alignment (cf. estimate region 82 in Figure 7) at the second object 36, indicated here at the vehicle region of the edge E2 of the vehicle 36.

During the parking operation, an ultrasound map is produced, as indicated in Figure 7. The approximate positioning in this case is based on a cross echo between the adjacent sensors 18, 28 and 24, 30, respectively, or the direct echo of the side sensors 28 and 30.

During the parking along the parking path 60, there exist differing locations 62, 64, 66, 68 of one and the same ultrasound sensor, being, in the present case, the first sensor 18 of the front sensors 16. It can be seen from the representation according to Figure 7 that, when these differing locations 62, 64, 66 and 68 are reached, differing ultrasound waves are emitted, or reflected, in respect of the first object, i.e. the first vehicle 34.

On the basis of the identified situation, i.e. the orientation of the transverse parking space 32 in respect of the drive-past direction (cf. representation according to Figures 1 to 4), in particular the portion 44 having a constant yaw angle, the metres covered, for example 5 metres, of the ultrasound map along the parking path 60 are evaluated. The width of the transverse parking space 32 and, accordingly, a sufficiently accurate target position -18 -in the centre between the two objects delimiting the transverse parking space 32 -in the present case, the first vehicle 34 and the second vehicle 36 -can then be calculated on the basis of the corner El and the first edge 70. As soon as the first edge 70 is detected, the alignment in relation to the target point can additionally be determined, it being desirable for the distance of the rear of the motor vehicle 10 in relation to the boundaries, i.e. to the first edge 70 of the first vehicle 34 and to the second edge 72 of the second vehicle 36, to be approximately equal.

After the driver assistance system has been activated and the driver has accepted its assuming of the control, the current steering must then be checked, such that a collision with the second vehicle 36 can be precluded.

Firstly, an instruction is given to the driver and a moment is applied to the steering wheel, in order to provide the driver with feedback concerning the direction in which the steering wheel is to be moved. As a result, an automated input is made into the steering apparatus, which input, if appropriate, can be supported by special acoustic, optical or haptic warnings.

Should, at first, no adequate solution be found for * completing the driving manoeuvre first initiated by the driver, i.e. forward parking in the detected transverse parking space 32, in the initial parking move along the parking path 60, the driver can be offered a further reverse move, or further forward moves, that originate either from a calculated path or on the basis of an adjustment to the target variables.