Procedure for performing a parking maneuver supported by a parking assistance system
Patent Information
- Authority / Receiving Office
- DE · DE
- Patent Type
- Patents
- Current Assignee / Owner
- AUMOVIO AUTONOMOUS MOBILITY GERMANY GMBH
- Filing Date
- 2018-11-27
- Publication Date
- 2026-07-30
Smart Images
Figure 00000000_0000_ABST
Abstract
Description
The invention relates to a method for carrying out a parking operation of a vehicle supported by a parking assistance system, a parking assistance system and a vehicle with a parking assistance system. Parking assistance systems are already known from the state of the art, enabling semi-automated or fully automated parking maneuvers. The parking assistance system maneuvers the vehicle into the parking position along a previously calculated parking trajectory. DE 10 2010 040 591 A1 describes a parking assistant for supporting a vehicle's parking maneuver when multiple parking spaces are available. One of the parking spaces is selected based on a comfort measure, which includes at least one predefined condition by which the parking spaces can be classified according to presumed driver acceptance. The comfort measure is determined based on the trajectory required for parking, and the vehicle is parked in the parking space with the fewest maneuvers in the trajectory. German patent DE 10 2008 058 652 A1 discloses a method for calculating the parking trajectory of a motor vehicle into a perpendicular parking space. This method determines a parking trajectory based on measurement data acquired with ultrasonic sensors. Furthermore, the measurement data is also generated during the parking process, whereby the appearance of obstacles and / or the vehicle falling below a certain distance to a surrounding object results in a recalculation of the parking trajectory. In DE 10 2016 109 852 A1, a method for maneuvering a motor vehicle into a parking space is described. A single parking trajectory, leading from a known starting point to a defined endpoint, is composed of circular arcs, lines, and clothoids, whereby an auxiliary trajectory is first created from circular arcs and lines, and then a clothoid segment is inserted in each of the transition areas between lines and circular arcs. In its simplest form, a parking trajectory is composed of several segments, where a segment can be either a straight line or a circular arc. Such a parking trajectory, consisting solely of straight lines and circular arcs, leaves the occupants of the vehicle with a low level of comfort, as the varying curvatures between the segments result in jerky parking behavior. Furthermore, it is known to implement transitions between segments using clothoids, which enable a curvature transition between the individual segments that is advantageous for the perceived comfort. The properties of the clothoid depend on a multitude of parameters, such as the vehicle speed during the parking maneuver, the steering speed, and the turning radius. However, a disadvantage is that calculating a parking trajectory, which is formed from straight lines, circular arcs and clothoids, is very complex due to the large number of parameters to be considered and therefore requires a lot of hardware resources and / or computing time. Based on this, the object of the invention is to provide a method for carrying out or controlling an at least partially automated parking process, which enables a time-efficient calculation of a parking trajectory with sufficient comfort even with limited hardware resources. The problem is solved by a method having the features of independent claim 1. Preferred embodiments are the subject of the dependent claims. A parking assistance system is the subject of dependent claim 8, and a vehicle with such a parking assistance system is the subject of dependent claim 9. According to a first aspect, the invention relates to a method for carrying out a parking operation of a vehicle supported by a parking assistance system. The method comprises the following steps: First, the parking assistance system is activated. This can be done by interaction of the driver with a user interface of the vehicle or automatically based on the current driving situation (e.g. driving slowly past a parking situation). The area surrounding the vehicle is then examined or scanned to identify unoccupied parking spaces. This preferably involves analyzing the vehicle's surroundings for characteristics such as parked vehicles, spaces between parked vehicles, obstructions, curbs, etc. The vehicle is equipped with suitable sensors (e.g., camera, radar, LiDAR, etc.) for this purpose. For example, an environmental map can be created around the vehicle, indicating the parking scenario. Preferably, the vehicle is moved during this process, for example, at a speed below a speed limit. Simultaneously, or at least partially overlapping, rough parking trajectory information is calculated to determine reachable, unoccupied parking positions. This rough parking trajectory information contains a multitude of parking trajectories, hereinafter also referred to as parking trajectory designs, to at least one reachable, unoccupied parking position. Each of these parking trajectories comprises at least one straight line and at least one circular arc segment. The parking trajectory designs each have a start position and an end position and indicate the path along which the vehicle can be moved from the start position to the end position. The start positions can vary due to the vehicle's movement, and the respective end position is determined by the specific unoccupied parking position into which the vehicle can be moved. Next, an accessible, unoccupied parking position is selected. This can, for example, be done through interaction between the driver and the vehicle's user interface. This selection preferably terminates the calculation of rough parking trajectory information. Subsequently, detailed parking trajectory information for the selected, unoccupied parking position is calculated, wherein the detailed parking trajectory information is based on a parking trajectory derived from the calculated rough parking trajectory information and comprises at least one straight line, at least one circular arc segment, and at least one clothoid. Preferably, the calculation of the detailed parking trajectory information includes the calculation of at least one detailed parking trajectory that is a complete parking trajectory formed from at least one straight line, one circular arc segment, and one clothoid. Finally, the parking assistance system performs at least a partially automated parking of the vehicle in the selected, unoccupied parking position based on the calculated detailed parking trajectory information. The key advantage of the method according to the invention lies in its ability to quickly calculate a large number of parking trajectory designs with limited hardware resources. In the first stage, a simplified pre-calculation of potentially possible parking trajectories for reaching a specific end position from a starting position is performed, and in the second stage, a detailed calculation is carried out. While these designs do not represent exact parking trajectories suitable for comfortable parking, they do provide an estimate of how a specific parking position can be reached from a given starting point. In the second stage, the detailed parking trajectory can then be calculated based on one of these pre-calculated parking trajectories. Due to the inclusion of at least one clothoid curve, this detailed trajectory offers a sufficiently comfortable driving experience. According to one embodiment, the rough parking trajectory information is calculated while the vehicle is in motion. Similar to a sampling method, the calculation begins at a specific position where the moving vehicle is currently located and checks which path can be taken from this current position to park in one or more unoccupied parking positions. This process is repeated iteratively until a parking position is selected. This creates a set of parking trajectory designs, based on which the detailed parking trajectory information can then be calculated. According to one embodiment, when calculating rough parking trajectory information, a set of parking trajectories is calculated, each of which is assigned an evaluation value. This evaluation value can be an indicator of the perceived comfort of a person in the vehicle when the vehicle is parked based on the respective parking trajectory. Thus, a feature of the respective parking trajectory, such as the perceived comfort, can be characterized via the evaluation value. According to one embodiment, after selecting an accessible, unoccupied parking position, a parking trajectory from the set of parking trajectories is chosen, taking into account the evaluation information. Based on this selected parking trajectory, the detailed parking trajectory information is then calculated. The evaluation information can, for example, be used for the selection process. The selected parking trajectory thus forms a kind of sketch or framework for the detailed parking trajectory to be calculated; that is, the detailed parking trajectory builds upon the selected parking trajectory and improves it, for example, with regard to perceived comfort. According to one embodiment, the detailed parking trajectory information is determined by a calculation comprising several iteratively executed computational loops. In other words, the detailed parking trajectory information, particularly for the inclusion of the clothoids, is not determined using an analytical computational method, but rather based on an approximate computational method. Such computational methods are computationally intensive, so the two-stage calculation of the parking trajectory achieves a significant reduction in computational time and resources. According to one embodiment, the calculation of the rough parking trajectory information checks whether a transition between a straight line and a circular arc segment, or between two circular arc segments, can be replaced or modified by a clothoid. This clothoid has a length calculated based on a minimum vehicle speed, selectable or predefined by the parking assistance system. In other words, the calculation of the rough parking trajectory information checks whether it is fundamentally possible to replace a transition between a straight line and a circular arc segment, or between two circular arc segments, with a clothoid.The test is based on the minimum vehicle speed during the parking maneuver, as this is when the clothoid length is shortest. If the transition cannot be modified by the clothoid at this minimum length, it will certainly not be possible at higher vehicle speeds. If the test shows that modifying or replacing the transition with a clothoid of minimum length is not possible, the calculated parking trajectory is preferably discarded; that is, it cannot be used later to calculate detailed parking trajectory information. According to one embodiment, when calculating detailed parking trajectory information, a transition between a straight line and a circular arc segment, or a transition between two circular arc segments, is replaced by a clothoid. This clothoid is calculated based on a vehicle speed greater than a minimum vehicle speed selectable or predefined by the parking assistance system during the parking process. For example, detailed parking trajectories for different vehicle speeds can be calculated, and the detailed parking trajectory that allows for the highest vehicle speed while maintaining a sufficiently high level of comfort can be used. According to a further aspect, the invention relates to a parking assistance system for controlling a vehicle's parking maneuver. The parking assistance system comprises: - one or more sensors designed to detect the vehicle's surroundings in order to identify unoccupied parking positions; - a processing unit for calculating rough parking trajectory information to determine reachable, unoccupied parking positions, wherein the rough parking trajectory information includes a plurality of parking trajectories to at least one reachable, unoccupied parking position, each of which comprises at least one straight line and at least one circular arc segment; - a user interface via which a reachable, unoccupied parking position can be selected;- a computing unit configured to calculate detailed parking trajectory information for the selected, unoccupied parking position, wherein the detailed parking trajectory information is based on a parking trajectory derived from the calculated rough parking trajectory information and the detailed parking trajectory information includes at least one straight line, at least one circular arc segment, and at least one clothoid; - a control unit for controlling at least a semi-automated parking maneuver of the vehicle into the selected, unoccupied parking position based on the calculated detailed parking trajectory information. According to another aspect, the invention relates to a vehicle with a parking assistance system as described above. For the purposes of this invention, a "parking process" is understood to mean processes in which a vehicle is maneuvered forwards, backwards, sideways, or diagonally into a parking space. The driver may be inside or outside the vehicle during the parking process (remote parking). A "parking process" can be either a parking maneuver or an exit maneuver. For the purposes of the present invention, "parking assistance system" means any system that provides support to the driver during the parking process and enables at least a semi-automated parking process. The terms “approximately”, “essentially” or “about” mean, within the meaning of the invention, deviations from the respective exact value by + / - 10%, preferably by + / - 5% and / or deviations in the form of changes that are insignificant for the function. Further developments, advantages, and possible applications of the invention will also become apparent from the following description of exemplary embodiments and from the figures. All features described and / or illustrated are, individually or in any combination, fundamentally the subject matter of the invention, irrespective of their compilation in the claims or their cross-reference. The content of the claims is also incorporated into the description. The invention is explained in more detail below with reference to exemplary embodiments shown in the figures. Figure 1 shows, by way of example and schematically, a parking situation with two unoccupied parking positions in a parallel parking situation; Figure 2 shows, by way of example, a block diagram illustrating the process sequences for carrying out a parking operation supported by a parking assistance system; and Figure 3 shows, by way of example and schematically, a parking trajectory composed of a straight line and two circular arc segments for forward parking into a parallel parking space. Fig. 1 shows a vehicle 1 in a parallel parking situation where some parking positions P1, P2 are unoccupied. The vehicle 1 has a parking assistance system that allows it to park itself, at least partially automatically, in an unoccupied parking position P1, P2. During the parking process, the vehicle 1 is maneuvered along a parking trajectory PT by the parking assistance system. An example of such a parking trajectory PT is shown in Fig. 1. A parking trajectory PT can consist of several segments. A segment can, for example, be formed by a straight line or a circular arc segment. To further improve the perceived comfort of the parking assistance system, a segment can also be formed by a clothoid. Using a clothoid, it is possible to compensate for the change in curvature between two circular arc segments or between a straight line and a circular arc segment. To perform the fastest possible calculation of a large number of possible parking trajectories (PT) with limited hardware resources, a multi-stage method is used. This is described in more detail below with reference to the block diagram shown in Fig. 2. First, the parking assistance system of vehicle 1 is activated (S10). This can be done manually by the driver, for example, or automatically in the case of autonomous driving or when vehicle 1 detects that the driver is looking for a free parking space. The area surrounding vehicle 1 is then scanned to identify an unoccupied parking position (S11). During the scan, suitable sensors (e.g., camera, radar sensor, lidar sensor, etc.) can be used to gather environmental information, which is then analyzed to identify available parking spaces. Furthermore, the scan can provide information about the parking situation, which can be presented, for example, as a map. This information includes details about the orientation of parking spaces, objects in the vicinity of vehicle 1, and so on. During this scanning of the surrounding area, vehicle 1 moves forward. The speed of vehicle 1 is preferably limited in order to be able to determine the environmental information. During the scanning of the surrounding area and preferably also the movement of vehicle 1, rough parking trajectory information is calculated (S12). A multitude of parking trajectories PT are calculated during this rough parking trajectory information calculation. These parking trajectories PT are subsequently also referred to as parking trajectory drafts, since they do not correspond to the final detailed parking trajectories used by the parking assistance system to carry out parking operations. The parking trajectory designs are preferably calculated while the vehicle 1 is in motion, resulting in a multitude of parking trajectory designs where the starting position at which the parking process begins changes. In other words, the calculation of rough parking trajectory information involves the sequential creation of a multitude of parking trajectory designs, similar to a sampling process. This calculation of rough parking trajectory information is intended to first determine, in principle, whether and how the vehicle can be parked in one or more unoccupied parking positions. When calculating rough parking trajectory information, the parking trajectory designs are first created based on straight lines and circular arc segments. Fig. 3 shows a detailed view of a parking trajectory design for parallel parking, where the parking trajectory design consists of three segments, each of which is either a straight line or a circular arc segment. In the example shown, segment S1 is a straight line, and segments S2 and S3 are circular arc segments. As can be seen, changes in curvature occur at the transitions between two segments. If the parking process were carried out based on this parking trajectory design, this would lead to uncomfortable parking behavior. To improve the parking behavior of the parking assistance system, the transitions can be modified by using clothoids. For example, a clothoid can be inserted between a straight line and a circular arc segment to adjust the change in curvature. A disadvantage of calculating the exact parking trajectories that can be used by the parking assistance system to carry out parking operations, and which include at least one straight line and one or more circular arc segments and at least one clothoid, is that the calculation is very complex, since the clothoid depends on a large number of parameters, such as the speed of the vehicle during the parking operation, the steering speed or the steering radius. To reduce the complexity of the calculations when scanning the surrounding area before selecting an unoccupied parking position and during vehicle movement, the calculation of the rough parking trajectory information either calculates parking trajectory designs without considering clothoids, i.e., solely considering straight lines and circular arc segments, or it calculates parking trajectory designs consisting of straight lines and circular arc segments and additionally checks whether one or more transitions between the segments can be modified by including a clothoid. However, assumptions are made for the calculations that simplify the calculation of the parking trajectory designs. For example, the calculation of the clothoids assumes that the vehicle is moving at a minimum parking speed. During the scanning of the surrounding area, the calculated rough parking trajectory information or parking trajectory designs are saved in order to be used later for the calculation of the detailed parking trajectories. The scanning of the surrounding area and the calculation of the rough parking trajectory information are performed until an unoccupied parking position P1, P2 has been selected. For example, after the driver of vehicle 1 has selected an accessible, unoccupied parking position P1 or P2 (S13), particularly via a corresponding user interface, detailed parking trajectory information is calculated (S14). This detailed parking trajectory information includes at least one detailed parking trajectory based on which the parking assistance system automatically moves vehicle 1 into the parking position. The detailed parking trajectory is based on a parking trajectory design previously determined as part of the calculation of the rough parking trajectory information. Selecting a parking trajectory design from a multitude of possible designs can be achieved, for example, by assigning each design a rating when calculating the rough parking trajectory information. This rating information is then used to select a specific parking trajectory design for calculating the detailed parking trajectory. The rating information can, in particular, be a comfort rating criterion, indicating how comfortable a particular parking trajectory design will be perceived by a driver. The detailed parking trajectory is calculated by determining it entirely based on at least one straight line, at least one circular arc segment, and at least one clothoid between a straight line and a circular arc segment, or between two circular arc segments. The calculation is not constrained by any assumptions, such as a fixed parking speed. Instead, the vehicle speed used during the parking maneuver is chosen to ensure the process is quick yet comfortable for the user. This is specifically a vehicle speed higher than the minimum speed required for successful parking. It goes without saying that the vehicle speed along the parking trajectory can be adjusted.For example, the vehicle can travel faster on straightaways or in curves with a small curvature than in curves with a larger curvature. Alternatively or additionally, the vehicle speed can be adjusted depending on the distance to surrounding objects. For instance, the vehicle speed can be reduced along the parking trajectory when the vehicle approaches an object. Conversely, the vehicle speed can be increased when there is a sufficient distance to surrounding objects. Since, as previously described, the length of a clothoid is indirectly dependent on the vehicle speed (via the maximum steering angle speed), and the clothoid length significantly influences the course of the parking trajectory and, in particular, its overall length and shape, it is preferable to calculate several detailed parking trajectories at different vehicle speeds and then select one of these detailed parking trajectories to execute the automated parking maneuver. The selection of a detailed parking trajectory can be based on the vehicle speed and / or a comfort criterion that indicates how comfortable the parking maneuver is for the respective driver based on the given detailed parking trajectory. After selecting a detailed parking trajectory, the at least partially automated parking process is then carried out in the selected, unoccupied parking position based on the selected detailed parking trajectory (S15). The invention has been described above using exemplary embodiments. It is understood that numerous modifications and adaptations are possible without thereby departing from the scope of protection defined by the patent claims. Reference symbol list 1 vehicle P1, P2 unoccupied parking positions PT Parking trajectory S1, S2, S3 segments
Claims
Method for performing a parking operation of a vehicle supported by a parking assistance system (1), comprising the following steps: - Activating the parking assistance system (S10); - Scanning the area surrounding the vehicle to identify unoccupied parking positions (P1, P2) (S11); - Calculating rough parking trajectory information (S12) to determine reachable unoccupied parking positions (P1, P2), wherein the rough parking trajectory information includes a plurality of parking trajectories (PT) to at least one reachable unoccupied parking position (P1, P2), each of which includes at least one straight line and at least one circular arc segment; - Selecting a reachable unoccupied parking position (P1) (S13);- Calculating detailed parking trajectory information for the selected, unoccupied parking position (P1) (S14), wherein the detailed parking trajectory information is based on a parking trajectory (PT) of the calculated rough parking trajectory information and the detailed parking trajectory information includes at least one straight line, at least one circular arc segment, and at least one clothoid; - at least semi-automated parking of the vehicle (1) in the selected, unoccupied parking position (P1) by the parking assistance system based on the calculated detailed parking trajectory information (S15).; Method according to claim 1, characterized in that the rough parking trajectory information is calculated during the movement of the vehicle (1). Method according to claim 1 or 2, characterized in that, when calculating rough parking trajectory information, a set of parking trajectories (PT) is calculated, each of which is assigned an evaluation information. Method according to claim 3, characterized in that after selecting an accessible, unoccupied parking position (P1), a parking trajectory (PT) of the set of parking trajectories is selected taking into account the evaluation information and the detailed parking trajectory information is calculated based on the selected parking trajectory (PT). Method according to one of the preceding claims, characterized in that the detailed park trajectory information is determined by means of a calculation comprising several iteratively performed calculation loops. Method according to one of the preceding claims, characterized in that, during the calculation of the rough parking trajectory information, it is checked whether a transition between a straight line and a circular arc segment or a transition between two circular arc segments can be replaced by a clothoid which has a clothoid length calculated on the basis of a minimum speed of the vehicle (1) selectable or specified by the parking assistance system. Method according to one of the preceding claims, characterized in that, in the calculation of the detailed parking trajectory information, a transition between a straight line and a circular arc segment or a transition between two circular arc segments is replaced by a clothoid, which is calculated on the basis of a speed of the vehicle (1) that is greater than a minimum speed of the vehicle (1) during the parking process that can be selected or specified by the parking assistance system. Parking assistance system for a vehicle (1) comprising: - one or more sensors designed to detect the area surrounding the vehicle (1) for determining unoccupied parking positions (P1, P2); - a computing unit for calculating rough parking trajectory information for determining reachable unoccupied parking positions (P1, P2), wherein the rough parking trajectory information includes a plurality of parking trajectories (PT) to at least one reachable unoccupied parking position (P1, P2), wherein these parking trajectories (PT) each comprise at least one straight line and at least one circular arc segment; - a user interface via which a reachable unoccupied parking position (P1, P2) can be selected;- a computing unit configured to calculate detailed parking trajectory information for the selected, unoccupied parking position (P1), wherein the detailed parking trajectory information is based on a parking trajectory (PT) of the calculated rough parking trajectory information and the detailed parking trajectory information includes at least one straight line, at least one circular arc segment, and at least one clothoid; - a control unit for controlling at least a partially automated parking operation of the vehicle (1) in the selected, unoccupied parking position (P1) based on the calculated detailed parking trajectory information.; Vehicle comprising a parking assistance system according to claim 8.