GB2486558A

GB2486558A - Parking aid which estimates a distance to the curb from vehicle width plus lateral offset to a parked vehicle

Info

Publication number: GB2486558A
Application number: GB1121442.6A
Authority: GB
Inventors: Marcus Schneider; Michael Schoenherr
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2010-12-14
Filing date: 2011-12-13
Publication date: 2012-06-20
Anticipated expiration: 2031-12-13
Also published as: GB2486558B; FR2973320B1; FR2973320A1; DE102010062996A1; GB201121442D0

Abstract

Parking a vehicle 10 is supported by a sensor 110 that measures the lateral distance 50 to a parked vehicle 20, 22 that delimits a parking space 30. The movement 60 of the vehicle into the space is then measured and the depth 70 (i.e. the lateral component of the movement) determined there-from. A warning signal (e.g. acoustic, optical or hapic) is emitted if the sum of the sensed lateral distance and the vehicle width 52 is less than the depth. The lateral distance may be measured by a short-range pulse-echo method (e.g. acoustic, laser or radio-wave) whose range is not greater than 1.5m, 2m or 2.5m. The movement may be measured using steering angle transmitter 114 and odometer 112 (e.g. wheel pulse counter). The vehicle may have front and rear distance sensors of the same design and/or range as the lateral sensor.

Description

Description Title

Method and device for supporting a parking operation of a tTehicle

Prior art

Known from the field of motor vehicles is the practice of using pulse echo methods for measuring distance, particularly for parking systems. Both active and passive parking support systems are known, which, by means of pulse echo detection, detect a parking space as the vehicle drives past. A parking trajectory is then calculated, this trajectory being followed by the vehicle itself in the case of active systems, and being indicated by a corresponding indication in the case of passive systems.

The publication US 2005/0195071 describes the use of rear and front distance sensors for measuring distance along the travel path of a vehicle, in the context of a parking operation. In addition, distance sensors on longitudinal sides of the vehicle are used in order that objects to the side of the vehicle can also be taken into account during parking. Vehicle-based distance sensors are also used to determine the movement of the vehicle on the basis of the travel path and the steering direction, to enable the parking trajectory actually followed to be compared with the planned parking trajectory. In this case, however, the distance sensors are used merely to provide warning, while the parking trajectory is being followed, of obstacles located to the side of, in front of or behind the vehicle.

Since the lateral distance sensors must be capable of gauging the parking space itself as the vehicle drives past, the lateral distance sensors must have a large range that covers the entire depth of the parking space. Lesser ranges suffice for the front and rear distance sensors, since these are used only for collision warning.

The method used in the prior art, of laterally scanning the parking space itself as the vehicle drives past, requires distance sensors having a large range. In the case of direct scanning of the parking space, the range must correspond at least to one vehicle width plus a minimum manoeuvring clearance, particularly since the vehicle cannot travel alongside already parked vehicles without a clearance. However, the costs for distance sensors having a large range are relatively high.

It is therefore an object of the invention to provide a possibility by which a parking operation can be supported, but without the necessity of using expensive distance sensors having an extended range.

Disclosure of the invention

The object is achieved by the subject-matter of the independent claims.

The invention makes it possible to use small-range distance sensors in the context of a parking operation, enabling the costs for the distance sensors to be reduced significantly.

As a result, the signal processing requirement for the distance sensors is also small, it being possible, in particular, to use distance sensors having a low emission power. This also enables the costs for the distance sensors to be reduced in comparison with the prior art.

The invention makes it possible, in particular, to use inexpensive, small-range distance sensors, but without affecting the precision of parking-space detection. A further advantage of the invention is that the parking path distance is reduced considerably, as compared with already known methods, since the depth of the parking space is determined without direct scanning of the parking space itself. The parking operation support according to the invention does not necessitate travel along the entire parking space, such that the path to be followed during reversing into the parking space is reduced considerably as

compared with the prior art. This results in a

considerably greater acceptance by drivers and in a reduced risk of accident, particularly where vehicles are relatively close together. In addition, the invention enables both the lateral distance sensors and the front and rear distance sensors to be of like design, resulting in considerably improved integration.

According to the invention, the depth of the parking space itself is not gauged but, rather, the depth of the parking space is deduced from the position of an already parked vehicle adjacent to the parking space. Therefore, instead of a scanning pulse being emitted from the parking vehicle, at the parking space, over the entire depth of the parking space, according to the invention it is necessary merely to determine the distance between the parking and the parked vehicle. It is assumed that the parked vehicle is correctly positioned in relation to a lateral obstacle, for example a kerb or a wall. The procedure according to the invention is based on a defined depth of the parking space, which corresponds to the width of a standard vehicle. A line that must not be crossed, describing, for example, the course of the kerb, is therefore given by an assumed, defined vehicle width and the distance determined between.

the parking vehicle and the parked vehicle. According to the invention, therefore, monitoring is performed as to whether the vehicle, when being driven into the parking space, is driven laterally into the parking space by more than the defined, assumed vehicle width plus the sensed distance between a parking and a parked vehicle. The result achieved is that the parking vehicle does not move over the line marked by that longitudinal side of the parked vehicle that is located on a side of the parked vehicle that faces away from the carriageway. In other words, according to the invention a warning is emitted if, because of a depth to which the parking vehicle is driven into the parking space, the vehicle goes over a virtual line representing the start of a lateral obstacle to which the parked vehicle is oriented. Taken as an orientation point in this case is the longitudinal side of the parked vehicle that faces towards the parking vehicle. The emission of the warning signal according to the invention therefore depends on the position of the parked vehicle, with the assumption that the latter is also oriented in relation to an obstacle such as a kerb. The sensing of the lateral distance from the parked vehicle thus serves to align the parking vehicle in relation to the parked vehicle. Since it is to be assumed that the parked vehicle is likewise oriented to a lateral obstacle, the result is that this obstacle is also taken into account as the parking vehicle is driven into the space.

The invention thus provides a method for supporting a parking operation of a vehicle, wherein a lateral distance from a parked vehicle is sensed. In particular, the lateral distance from a parked vehicle delimiting a parking space is sensed, the sensing being based on a pulse echo method. In this method, scanning pulses are emitted by the parking vehicle, which pulses are reflected from the parked vehicle, in order to measure the distance on the basis of the propagation time. Further, measurement of a movement of the vehicle is used to sense a depth to which the parking vehicle is driven into the parking space. The parking vehicle is driven into the parking space after the lateral distance from the parked vehicle has been sensed.

The movement of the parking vehicle is measured, in particular, by sensing the direction of movement, or a steering angle. In addition, a travel path of the parking vehicle is measured. The measurement of the parking vehicle relates to the movement of the parking vehicle in relation to the background against which the vehicle is moving. The sensed distance, plus a defined vehicle width, is compared with the sensed depth. The sensed distance in this case can be added to the defined vehicle width before the resultant sum is compared with the sensed depth, or arithmetic calculations equivalent to this can be performed in order to compare the sizes.

The vehicle width is defined and, in particular, is constant. The defined vehicle width is used to estimate how far the side of the parked vehicle sensed by the pulse echo method is from the opposite side of the parked vehicle, it being assumed that on the opposite side there is likewise an obstacle to which the parked vehicle is oriented. The defined vehicle width can correspond to a standard vehicle width, for example 1.5 m, 1.7 m or 2 m, and can further comprise a (negative) protective width, for example a width required for opening side doors of the vehicle. Instead of or in combination with the protective width, a further (negative) safety distance can be provided, which serves to avoid collision in the case of driver error. Both the protective width and the safety width are subtracted from the defined vehicle width before the latter is used for comparison with the sensed depth.

A warning signal is emitted if the sensed distance, plus the defined vehicle width, is less than the sensed depth.

Thus, a warning signal is emitted if, because of the movement of the parking vehicle, the latter goes too far laterally into the parking space, in particular by more than the sum of the defined vehicle width and a sensed distance. The warning signal is therefore emitted if the side of the parking vehicle that faces away from the carriageway goes over the virtual line marking the longitudinal side of the parked vehicle that faces away from the carriageway. Thus, if the side of the parking vehicle that faces away from the carriageway goes beyond the side of the parked vehicle that faces away from the carriageway, the warning signal is emitted. The comparison assumes that the parked vehicle is of the defined vehicle width. If the vehicle width of the parked vehicle actually differs from the defined vehicle width, this difference is reflected in the orientation of the parking vehicle in relation to the parked vehicle. To enable such differences to be compensated, the defined vehicle width can be increased by an additional safety value.

The distance is sensed, as mentioned, by means of a pulse echo method, wherein distance sensors emit and receive back a scanning pulse. The pulse echo method can be executed by means of acoustic, laser-based or radio-wave-based distance sensors. The pulse echo method in this case can be executed by one distance sensor or a plurality of distance sensors. The at least one distance sensor is disposed on the longitudinal side of the parking vehicle, which faces away from the centre of the carriageway. In the case of right-side traffic, this corresponds to the right flank of the vehicle and, in the case of left-side traffic, this corresponds to the left flank of the vehicle. The distance sensors that execute the pulse echo method for sensing the distance have a range of not more than 1.5 m, 2 m or 2.5 m.

Such distance sensors are standard distance sensors, and correspond to sensors mounted on a front or a rear of a vehicle for collision avoidance.

The range of the at least one lateral distance sensor is oriented to a maximally usual distance between a vehicle and the boundary of the carriageway on which the vehicle is moving. An acoustic distance sensor comprises, in particular, a piezoelectric transducer, which transmits and/or receives an acoustic scanning pulse. The distance sensor can further be a LIDAR sensor. Finally, the distance sensor can be a distance sensor controlled by radio waves, for example a microwave-based distance sensor comprising antennae that transmit and/or receive a

-B-

microwave scanning pulse. In the latter, microwave-based variant, the distance sensor thus corresponds to a radar sensor.

The sensing of the depth to which the parking vehicle is driven into the parking space serves to verify whether or not the assumed, defined vehicle width has already been fully utilized by the movement of the vehicle into the depth of the parking space. This depth is sensed by measurement of a path distance. The latter relates to the travel path of the vehicle as it is driven into the parking space. Preferably, the depth is sensed in that a path distance is measured in combination with a steering angle.

The path distance or the combination of the steering angle and the path distance are sensed continuously, the movement of the parking vehicle into the parking space being sensed continuously or at least repeatedly. The movement is thereby tracked on the basis of the path distance and the steering angle. Integration of this movement, i.e. appropriate integration of the steering angle and the path distance over time, results in the depth to be sensed. In this case, the vertical component of the movement is considered and integrated to enable the total lateral offset of the parking vehicle, and thus the depth, to be deduced. The vertical component of the movement relates to the movement component of the parking vehicle that is perpendicular to the longitudinal alignment of the parking space.

The path distance is measured by means of an odometer attached to the parking vehicle. In particular, a wheel pulse counter of the parking vehicle is used for this purpose, the wheel pulse counter sensing the motion of the wheels of the vehicle. The odometer, or wheel pulse counter, are thus coupled to the drive of the parking vehicle, in order to deduce therefrom the movement of the parking vehicle. As an alternative to the odometer, for the purpose of measuring the movement of the parking vehicle it is also possible, in principle, to use a position determination system, for example a GPS system or other radio-assisted location determination system, provided that the position determination system concerned has a sufficient accuracy for determining the depth. The steering angle is measured by means of a steering-angle transmitter, which is connected to the steering system of the parking vehicle. Such a steering-angle transmitter is, for example, an angle sensor, which senses the lock of the steering linkage of the parking vehicle. The orientation angle of the vehicle in relation to the parking space is obtained from the integral of the steering angle over the path distance of the movement of the parking vehicle. The integral of the orientation angle over the path distance travelled gives, in turn, the lateral offset, and therefore the depth by which the parking vehicle is driven in. It is to be noted in this case that the depth is affected by the component of the aforementioned quantities that is perpendicular to the parking space, it being necessary to take this into account in the case of the aforementioned integrals.

According to an embodiment of the invention, the parking operation is supported merely in a passive manner, such that there is no automatic intervention in either the steering or the drive control of the parking vehicle.

-10 -Rather, the driver receives corresponding signals, in particular warning signals, in order to operate the vehicle accordingly. The parking vehicle is thus driven into the parking space in accordance with steering and drive selections made by the driver. The warning signal is emitted acoustically, optically or haptically. The warning signal can be emitted even at a stage when the sensed distance, plus the defined vehicle width, is not less than the sensed depth, but the difference between the sensed distance, plus the defined vehicle width and the depth, is less than a predetermined limit. Beyond this limit, the warning signal is emitted, the intensity or other property of the warning signal being able to increase if the difference reduces further. In particular, the repetition frequency of an acoustic signal can increase the more the sensed distance, plus the defined vehicle width, approximates to the sensed depth. A similar dependence can be provided between the difference and the warning signal, as is the case with known front or rear distance sensors for collision avoidance. The sensitivity with which the warning signal is emitted can be further increased in that the defined vehicle width is additionally reduced by a given amount, such that the warning signal is emitted at the stage when the parking vehicle is approaching the obstacle, or the kerb. The defined vehicle width can therefore be, for example, 1.3 or 1.1 m, in order that the warning signal is emitted at a stage before a critical point, despite the fact that a standard vehicle width is assumed to be, for example, 1.5 m, 1.7 m or 2 m. The given amount by which the vehicle width is reduced corresponds to the protective width or safety distance described above.

-11 -An alternative eriibodirnent provides that the parking operation is supported in an active manner, with automatic intervention at least in the steering or in the drive control. In this case, the warning signal is included in S control data by which the steering and/or the drive control are actuated.

According to an embodiment of the method wherein, however, the parking operation is supported in a passive manner, the warning signal is emitted by means of an acoustic transmitter. This transmitter also enits longitudinal distance signals that originate from front and/or rear distance sensors of the parking vehicle. Such longitudinal distance signals correspond to collision signals of standard parking aid systems. Preferably, the warning signal according to the invention and the longitudinal distance signals have differing tone levels or differing tone characteristics and/or differing sounds. This enables the driver to distinguish lateral distance signals from longitudinal distance signals. Further, the warning signal can be output by a loudspeaker on the side of the vehicle on which the parking space is located, while longitudinal distance signals are output, according to their signal origin, by loudspeakers in the vehicle that are located at the rear or at the front. The transmitter and the loudspeakers are accommodated, in particular, in the passenger compartment, at the appropriate locations.

It is furthermore provided that the lateral distance is sensed by at least one distance sensor, which is attached to a side of the parking vehicle. Any front and/or rear distance sensors of the parking vehicle sense at least one -12 -longitudinal distance of the parking vehicle in relation to the parked vehicle. These front and/or rear distance sensors correspond to the above-mentioned distance sensors for collision warning by parking systems in the longitudinal direction. The front and/or rear distance sensors are of the same design or have the same range as the at least one distance sensor attached to a side of the vehicle. This simplifies servicing and connection to a central unit, since all distance sensors have the same properties.

Finally, it is provided that the parking space into which the parking vehicle is driven is a longitudinal parking space. The direction of the longitudinal extent of the parking space thus corresponds to the direction of travel of the carriageway that runs next to the parking space.

The parking vehicle first travels past the parking space in a direction corresponding to the direction in which the parking space extends. The vehicle in this case can drive past the parking space in its entirety or, also, only partially. In a specific embodiment, the vehicle travels past a parked vehicle that is next to the parking space.

The parking vehicle in this case does not travel past the parking space in its entirety. Instead, the lateral distance from the parked vehicle that is followed by the parking space is sensed, such that it is not necessary to determine the distance from a further parked vehicle that is opposite the first-mentioned parked vehicle.

Alternatively, the parking vehicle can travel past the parking space in order to sense the lateral distance from the parked vehicle that follows the parking space in the direction of travel.

-13 -The method can be realized, in particular, by means of a microprocessor and a program that runs on the latter and realizes features of the method according to the invention.

In particular, the method can be realized in a processor, which, by means of another program, realizes a longitudinal collision warning system.

Finally, the invention is realized by means of a device for supporting a parking operation of a vehicle. The device comprises an input interface, which is set up for connection to a lateral distance sensor of the vehicle.

Further, the input interface is set up for connection of an odometer and a steering-angle transmitter. The device further comprises a movement evaluation means, which is connected to the input interface. The purpose of the movement evaluation means is to evaluate the movement, sensed by means of the odometer and the steering angle transmitter, in respect of the depth to which the parking vehicle is driven into the parking space. The depth to which the vehicle is driven into the parking space corresponds to the lateral offset of the vehicle resulting from the parking operation. The movement evaluation means is set up to calculate the lateral offset of the movement of the vehicle, as a depth value, on the basis of data of the odometer and of the steering angle transmitter. The depth value indicates the depth to which the parking vehicle is driven laterally into the parking space. The device comprises a comparator, which is connected in series after the movement evaluation means. The comparator is set up to compare a distance value, provided by the lateral distance sensor, plus a defined vehicle width value, with -14 -the depth value. The comparator is provided to emit a warning signal if the distance value, plus the vehicle width value, is less than the depth value. For this purpose, the device can comprise a totalizer, which adds the distance value to the defined vehicle width value before the distance value is compared with the depth value.

The comparator can be a binary comparator, having only two output states, or it can be a multi-stage or continuous comparator, which determines the difference between two values. The difference corresponds to the proximity of the parking vehicle to a critical boundary.

Brief description of the drawings

Figure 1, for the purpose of explaining the method, shows a traffic situation and shows a vehicle equipped with a device according to the invention.

In Figure 1, a parking vehicle 10 is represented schematically in a first position 40 and in a second position 42. Also represented schematically are parked vehicles 20 and 22. Between the parked vehicles 20 and 22 there is a longitudinal parking space 30. In a first position 40, the parking vehicle 10 is oriented parallel to the parked vehicle 20. A lateral distance 50 that exists between the parked vehicle 20 and the parking vehicle 10 is sensed in this case. In a subsequent, second position 42, the vehicle 10 has already been driven partially into the parking space 30. The movement 60 during driving into the parking space 30 has been measured, and the depth 70 to which the vehicle 10 in position 42 has already entered the parking space 30 has been sensed. The depth 70 corresponds -15 -to a lateral offset of the vehicle 10 in relation to the original travel path 80, which goes past the parking space 30. The movement 60 corresponds to a depth 70 actually travelled. The original travel path 80 corresponds to the movement of the vehicle 10 as it travels past the parking space 30, and denotes the course of a traffic lane. For the purpose of illustrating the method according to the invention, the figure also shows, in addition to the depth 70, the sensed distance 50, plus a defined vehicle width 52. It can be seen that the sensed distance 50 plus the defined vehicle width 52, is greater than the sensed depth 70, but with the difference 54 being reduced as a movement into the parking space progresses further. It is evident from consideration of Figure 1 that the instant of the warning, i.e. in the case of a difference 54 of zero, the vehicle 10 is close to a lateral delimitation 90, to which the parked cars 20, 22 are also oriented, but at the instant of the warning the vehicle 10 has not yet collided with the delimitation 90. As already noted, the defined vehicle width 52 can be additionally reduced in accordance with a safety distance. Owing to the safety distance, the warning signal is emitted when there is still a safety distance between the vehicle 10 and the delimitation 90.

It can further be seen from Figure 1 that it suffices to sense the distance 50 between the parking vehicle 10 and the parked vehicle 20 located in front of the parking space 30. Additional sensing of the lateral distance from the parked car 22 located after the parking space 30 is nnt-necessary, but may be performed, and may be combined, for example, with the lateral distance from the vehicle 20.

The distances between the parking car 10 and the parked car -16 -or the parked car 22 can be averaged, the result of the averaging being considered as the sensed distance.

In position 40, the parking car 10 is further represented with a device according to the invention. This device comprises an input interface 100, which is set up to be connected to a lateral distance sensor 110, an odometer 112 and a steering-angle transmitter 114 of the parking vehicle 10. The odometer 112 and the steering-angle transmitter 114 in this case are connected to corresponding devices of the vehicle drive. The connection is represented symbolically, the drive being represented by a dotted line.

The device further comprises a movement evaluation means 120, which is connected to the input interface 100. This movement evaluation means receives, in particular, sensor signals from the odometer 112 and the steering-angle transmitter 114. The movement evaluation means 120 is set up to calculate the lateral offset of the movement 60 of the vehicle 10, as a depth value, on the basis of sensor signals of the odometer 112 and of the steering-angle transmitter 114. The depth value in this case corresponds to the depth 70. The device further comprises a comparator 130, which is connected in series after the movement evaluation means 120. The comparator 130 therefore receives the depth value from the movement evaluation means 120. The comparator additionally receives a distance value from the input interface 100. The distance value is supplied by the distance sensor 110. A defined vehicle width value is stored in a memory 140, which is preferably provided in the comparator. In an alternative embodiment (not represented), a memory 140 is provided that is external to the comparator 130 and connected to the latter.

-17 -The vehicle width value is stored in the memory 140 and is preferably constant. The memory can be a read-only memory.

The comparator further comprises a totalizer 150, which adds the depth value of the input interface 100 to the defined vehicle width value of the memory 140. The comparator is set up to compare this sum with the depth value output by the movement evaluation means 120 to the comparator 130. The comparison result is output at a comparator output 160 of the comparator 130.

The data that is collected by the odometer 112 and the steering-angle transmitter 114 and transferred to the movement evaluation means 120 via the input interface 100 results in the depth value, which corresponds to the depth 70. The depth value is transferred to the comparator 130.

Via the input interface 100, the comparator 130 additionally receives the distance value provided by the distance sensor 110. The distance value corresponds to the distance 50. The vehicle width value stored in the memory 140 is added to the distance value. The adding function is provided by the totalizer 150. The defined vehicle width value stored in the memory 140 corresponds to the defined vehicle width 52.

Claims

-18 -Claims 1. Method for supporting a parking operation of a vehicle (10), comprising the steps: sensing, by means of a pulse echo method, a lateral distance (50) from a parked vehicle (20, 22) that delimits a parking space (30); sensing a depth (70) to which the parking vehicle (10) is then driven into the parking space, through measurement of a movement (60) of the parking vehicle (10) into the parking space; comparing the sensed distance (50), plus a defined vehicle width (52), with the sensed depth (70), and emitting a warning signal if the sensed distance, plus the defined vehicle width, is less than the sensed depth(70).
2. Method according to Claim 1, the pulse echo method for sensing the lateral distance (50) being executed by at least one acoustic, laser-based or radio-wave-based distance sensor (110), whose range is not greater than the defined vehicle width (52), in particular not greater than 1.5 m, 2 m or 2.5 m.
3. Method according to Claim 1 or 2, the depth (70) to which the parking vehicle (10) is driven into the parking space (30) being sensed in that a path distance of the movement (60) is measured, preferably in combination with a steering angle, the path distance being measured by means of an odometer (112) attached to the parking vehicle (10), in particular by means of a wheel pulse counter of the parking vehicle (10), and the steering angle being measured by means -19 -of a steering-angle transmitter (114), which is connected to the steering of the parking vehicle (10).
4. Method according to any one of the preceding claims, the parking operation being supported in a passive manner, the parking vehicle being driven into the parking space (30) in accordance with steering and drive selections made by the driver, and the warning signal being emitted acoustically, optically or haptically.
5. Method according to Claim 4, the warning signal being emitted by means of an acoustic transmitter, which also emits longitudinal distance signals that originate from front and/or rear distance sensors of the parking vehicle, the warning signal and the longitudinal distance signals preferably having a differing tone level, a differing tone characteristic or a differing sound.
6. Method according to any one of the preceding claims, the lateral distance (50) being sensed by at least one distance sensor (110) attached to a side of the parking vehicle (10), and front and/or rear distance sensors of the parking vehicle (10) further sensing at least one longitudinal distance of the parking vehicle (10) from the parked vehicle (20, 22), and the front and/or rear distance sensors being of the same design or having the same range as the at least one distance sensor (110) attached to a side of the vehicle.

-20 -
7. Method according to any one of the preceding claims, the parking space (30) being a longitudinal parking space, and the parking vehicle (10) first travelling laterally past the parking space (30) in a direction corresponding to the direction in which the parking space extends.
8. Device for supporting a parking operation of a vehicle (10), the device comprising: an input interface (100) set up for connection of at least one lateral distance sensor (110) of the vehicle (10), and for connection of an odometer (112) and of a steering-angle transmitter (114), the device further comprising a movement evaluation means (120), which is connected to the input interface (100) and which is set up to calculate a lateral offset of the movement of the vehicle (10), as a depth value, on the basis of data of the odometer (112) and of the steering angle transmitter (114), the device comprising a comparator (130), whicfh is connected in series after the movement evaluation means (120) and which is set up compare a distance value, provided by the lateral distance sensor (110), plus a defined vehicle width value, with the depth value, and to emit a warning signal if the distance value, plus the vehicle width value, is less than the depth value.
9. A device substantially as herein described with reference to the accompanying drawings.