Control unit for a parking and / or maneuvering assistance system and method for carrying out an automated parking and / or maneuvering maneuver

Abstract

Method for performing an automated parking maneuver and / or maneuvering maneuver of a motor vehicle (1) by means of an electronic control unit (2), wherein the method comprises, - Determining a parking and / or maneuvering trajectory for the vehicle, - Determining a current wheel circumference using two function modules (3, 4), wherein the function modules (3, 4) each perform two different procedures for determining a first and a second wheel circumference, wherein the first wheel circumference is preferably applied according to the first procedure (3) and wherein the second wheel circumference is applied according to the second procedure (4) if a predetermined condition is met, and - Performing an automated parking and / or maneuvering operation along the trajectory based on the current wheel circumference determined in this way, whereby - the first method (3) is a GPS data-related method, - the second method (4) is a non-GPS data-related method and - the specified condition is the presence of missing or inadequate GPS data (5).

Description

[0001] The invention relates to a parking and / or maneuvering assistance system and a corresponding method for performing an automated parking and / or maneuvering maneuver with at least automated lateral guidance for motor vehicles, in particular for passenger cars. For the prior art, reference is made to DE 10 2015 204 129 A1 and DE 10 2016 103 637 A1.

[0002] Known parking assistance systems with at least automated lateral guidance typically use ultrasonic sensors to measure a parking space and its surroundings before initiating the parking maneuver. Based on this measurement, they calculate a parking trajectory with a designated parking position as the endpoint. The parking assistance system then guides the vehicle into the parking space along this trajectory in one or more maneuvers.

[0003] In parking and / or maneuvering assistance systems with automated lateral guidance, the system takes over the vehicle's steering during automated parking and / or maneuvering. The driver must maintain longitudinal control through appropriate acceleration and braking. In parking and / or maneuvering assistance systems with both automated lateral and longitudinal guidance, the system also partially or completely takes over longitudinal control, depending on the level of automation. For example, the system may control the steering, brakes, vehicle propulsion, and direction of travel (forward or reverse).With such parking and / or maneuvering assistance systems, the driver has the option, for example, of being able to park the vehicle independently and optionally have it parked out of the parking space by operating a control element, such as a button.

[0004] Known parking and / or maneuvering assistance systems typically support longer reversing maneuvers and / or reversing parallel parking into a parallel parking space, with the vehicle driving automatically in reverse with automated lateral guidance and, if necessary, automated longitudinal guidance in one or more maneuvers along a calculated maneuvering trajectory and / or parking trajectory.

[0005] Newer parking and / or maneuvering assistance systems sometimes also support reversing into perpendicular parking spaces, whereby the vehicle preferably reverses into the space with automatic lateral guidance and, if necessary, automatic longitudinal guidance in one or more maneuvers along a calculated parking trajectory. Perpendicular parking spaces can also include angled parking spaces, which are not perpendicular to the roadway.

[0006] A well-known parking and / or maneuvering assistance system with lateral guidance is described, for example, in the applicant's unpublished DE 10 2015 204 129 A1.

[0007] It is crucial to know the exact tire circumference. Only then can it be ensured that the calculated and actual parking and / or maneuvering trajectories match precisely. If the deviation between the assumed and actual tire circumference is too large, this will lead to a poor maneuvering and / or parking result, with the vehicle either coming to a stop too far from the target position and / or too far outside the parking space or on the curb.

[0008] Methods for determining tire circumference have long been known in many forms. For example, according to DE 197 45 734 A1, the tire circumference is estimated to determine the tire's tread depth.

[0009] ABS and / or other vehicle dynamics control systems generally include wheel speed sensors to determine wheel rotation speed, the signals from which can be summed. This allows the individual distances traveled by each wheel over a given period of time to be calculated, taking into account the circumference of each wheel and the total number of its rotations. These calculated distances are subsequently referred to as wheel distances.

[0010] Changing a tire can lead to a significant change in the tire radius or tire circumference.

[0011] A change in tire circumference can be detected by comparing the wheel distances with a reference distance over the same period of time. A Global Positioning System (GPS), particularly in conjunction with a vehicle-integrated navigation system, can preferably be used to determine the reference distance.

[0012] Known parking and / or maneuvering assistance systems for the applicant's vehicles without a navigation system or GPS usually assume a medium tire size, which can deviate significantly from the actual tire size for some tire types.

[0013] Methods for determining the circumference of a wheel of a vehicle with at least two wheels are also known, depending on the yaw rate of the vehicle as well as the rotational speeds and / or distances between the wheels.

[0014] The invention is based on the objective of increasing the accuracy of a parking and / or maneuvering assistance system.

[0015] According to the invention, this problem is solved by the features of the independent claims, while preferred embodiments of the invention are specified in the dependent claims.

[0016] The invention provides for the use of at least two different methods for determining the tire circumference, which are selectively used depending on defined conditions.

[0017] This includes at least one first GPS data-related method and a second non-GPS data-related method, whereby the first method is used preferentially and the second method is only selected if GPS data is missing or inadequate.

[0018] It is generally assumed that changing a tire while driving is not possible. Therefore, if usable GPS data is available at least once during a journey, the wheel circumference determined using the first method is preferably used for a potentially subsequent automated parking or maneuvering operation. However, if only missing or insufficient GPS data is available after the vehicle has been started, the system switches to the second method, which is not based on GPS data, preferably a yaw rate-based method.

[0019] The yaw rate-based method learns a wheel circumference, particularly during cornering. Therefore, in a further development of the invention, the second method for determining the wheel circumference is applied after the vehicle has been started up, at least until the vehicle has covered a defined distance (e.g., travel time or distance) when only missing or insufficient GPS data is available. The defined distance is specified such that a sufficient number and / or sufficiently tight curves are available for the algorithm to determine a yaw rate-based wheel circumference. A yaw rate-based wheel circumference is also calculated, in a manner known per se, by means of the difference in wheel rotational speeds between a wheel on the outside of a curve and a wheel on the inside of a curve. The radius of the curve within a specific range is particularly advantageous in this case.It is particularly preferred to wait for a number of curves within the specified radius band in order to determine the yaw rate-related (second) wheel circumference, which can then be used for a possibly subsequent automated parking maneuver and / or maneuvering maneuver.

[0020] It should also be noted that in a third method, as is already the case according to the state of the art, a stored default wheel circumference is used as a substitute value if a sufficiently accurate wheel circumference could not be determined using either the first or the second method. The term wheel circumference also encompasses any other quantity proportional to the wheel circumference, such as the wheel diameter or the wheel radius.

[0021] The determined wheel circumferences are saved when the vehicle is parked, but are re-evaluated according to the above-mentioned procedures when the vehicle is restarted.

[0022] The insights gained during the development of parking and / or maneuvering assistance systems also led to a general inventive idea, independent of parking and / or maneuvering assistance systems, of using at least two different methods for determining the tire circumference of a motor vehicle in an electronic control unit. These methods are selectively used depending on defined conditions, with at least one first GPS-data-based method and a second non-GPS-data-based method being provided. The first method is preferably used, and the second method is selected only when GPS data is missing or insufficient. This idea can also be used in control units of other vehicle systems that also perform functions dependent on wheel circumference, such as all-wheel drive systems or vehicle dynamics control systems.

[0023] According to another aspect, the control unit contains a software (SW) program. This SW program can be configured to run on a processor (e.g., on a vehicle's control unit) and thereby execute one or more of the procedures described in this document.

[0024] According to another aspect, a storage medium is present. The storage medium may contain a software program that is configured to run on a processor and thereby execute one or more of the procedures described in this document.

[0025] It should be noted that the methods, devices, and systems described in this document can be used both alone and in combination with other methods, devices, and systems described in this document. Furthermore, any aspect of the methods, devices, and systems described in this document can be combined with one another in a variety of ways. In particular, the features of the claims can be combined with one another in a variety of ways.

[0026] An embodiment of the invention is described with reference to the drawing. The single figure schematically shows a vehicle with advantageous components that may be applicable to the invention.

[0027] A vehicle 1 has a control unit 2 for a parking and / or maneuvering assistance system for performing an automated parking maneuver. The control unit 2 has a first functional module, not shown in detail here, for determining a parking trajectory for the vehicle 1, which is known from the prior art. Determining a parking trajectory and performing the parking maneuver based on it requires knowledge of the wheel circumference, which must be determined as precisely as possible beforehand.

[0028] The control unit 2 contains the signals from a yaw rate sensor 6 and a GPS sensor 7. Furthermore, the wheel speeds n1 and n2 of at least two wheels (one outer and one inner wheel during cornering or turning maneuvers) are input signals to the control unit 2.

[0029] The control unit 2 contains a second functional module 3 for determining a first current wheel circumference according to a first method and a third functional module 4 for determining a second current wheel circumference according to a second method. The second functional module 3 processes the GPS data 5 from the GPS sensor 7 within the first method. The third functional module 4 processes at least the signals from the yaw rate sensor 6 and preferably also the wheel rotation speeds n1 and n2 within the second method.

[0030] The first method is preferably used. The second method is used if, after (re)commissioning of the vehicle 1, missing or defective GPS data 5 are available and if, preferably, the vehicle has also covered a defined distance from the time the missing or defective GPS data 5 became available or after the vehicle 1 was commissioned.

[0031] A fourth functional module, not shown in detail, performs an automated parking maneuver along the parking trajectory in a manner known per se - but based on the current first or second wheel circumference determined beforehand according to the invention.

[0032] The functional modules are, in particular, corresponding software programs.

Claims

[1] Method for performing an automated parking maneuver and / or shunting maneuver of a motor vehicle (1) using an electronic control unit (2), wherein the method comprises, - Determining a parking and / or maneuvering trajectory for the vehicle, - Determining a current wheel circumference using two function modules (3, 4), wherein the function modules (3, 4) each perform two different procedures for determining a first and a second wheel circumference, wherein the first wheel circumference is preferably applied according to the first procedure (3) and wherein the second wheel circumference is applied according to the second procedure (4) if a predetermined condition is met, and - Performing an automated parking and / or maneuvering operation along the trajectory based on the current wheel circumference determined in this way, whereby - the first method (3) is a GPS data-related method, - the second method (4) is a non-GPS data-related method and - the specified condition is the presence of missing or inadequate GPS data (5). [2] Method according to any of the preceding claims, characterized by , that - the second method for determining the wheel circumference in the event of missing or inadequate GPS data (5) shall be applied from the first commissioning of the vehicle at least until the vehicle has covered a defined distance and / or time. [3] Control unit (2) for a parking and / or maneuvering assistance system in a vehicle (1) for carrying out the method according to one of the preceding claims, wherein the control unit (2) comprises, - a first functional module for determining a parking and / or maneuvering trajectory for the vehicle, - a second functional module (3) for determining a first current wheel circumference according to a first method and a third functional module (4) for determining a second current wheel circumference according to a second method, wherein the first method is preferably applied and wherein the second method is applied when a predetermined condition is met, and - a fourth functional module for performing an automated parking and / or maneuvering operation along the trajectory based on the current first or second wheel circumference determined in this way, wherein - the first method (3) is a GPS data-related method, - the second method (4) is a non-GPS data-related method and - the specified condition is the presence of missing or inadequate GPS data (5). [4] Control unit (2) according to the preceding claim, characterized by , that - the second method for determining the wheel circumference in the presence of missing or inadequate GPS data (5) shall be applicable from the first commissioning of the vehicle at least until the vehicle has covered a defined distance and / or time.

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