Procedure for identifying a suitable parking space

Abstract

Method for determining a suitable parking space for a vehicle using sensors for measuring gaps between objects detected laterally by the vehicle, wherein the sensors for measuring gaps between objects detected laterally by the vehicle are activated both to the right and to the left of the vehicle, characterized in that the signals of these sensors are evaluated in such a way that, by comparing information obtained from the signals with predefined patterns (M1, M2) in the form of a temporal sequence of relative maxima and minima with their change over time or over a defined distance, it is determined whether the objects detected on the right and left sides of the vehicle are stationary or moving longitudinally.

Description

The invention relates to a method for determining a suitable parking space according to the preamble of claim 1. To assist drivers in finding parking spaces, automatic parking space measurement systems are available that determine the length and depth of a potential parking space. The system then indicates to the driver whether their vehicle will fit. This function is conceivable for both the right and left sides of the street. However, using this function is only practical if the driver actually intends to park. Therefore, the parking space measurement typically requires manual activation by the user. Additionally, a side selection must be made. It is known that this selection is made by analyzing the driver's turn signal activation. An additional switch for side selection would be possible, but too complex. From DE 102 58 310 A1 a method for determining a suitable parking space is known in which a side selection is made by determining the oncoming traffic via a radar unit. DE 198 06 150 C1 discloses a vehicle with an object detection device for detecting objects within a defined horizontal area of ​​observation using means for radiation-based scanning of the observation area. An evaluation unit can analyze strip-shaped sub-areas of the observation area. The analysis is time-resolved and based on the response sequence of the sub-areas to distinguish moving objects from stationary objects. German patent DE 102 57 722 A1 discloses a parking aid with a measuring unit for detecting parking spaces as the vehicle drives past them. This parking aid can be automatically activated when the vehicle speed falls below a predetermined level. Furthermore, DE 10 2004 046 589 A1 describes a device for a motor vehicle with at least one distance sensor for detecting a predominantly lateral distance between the motor vehicle and objects. The device also includes a control device by means of which the measurement reception time of the distance sensor can be changed. Finally, DE 101 36 981 A1 discloses a method for determining a stationary and / or moving object, in which acoustic signals emitted by the object and / or reflected by another object are recorded as a reference signal, on the basis of which the object in question is detected, evaluated and / or identified. The object of the invention is to further develop the method of the type mentioned above with regard to automatic page selection while saving on sensors. This problem is solved according to the invention by the subject matter of claim 1. Advantageous embodiments are the subject matter of the dependent claims. In the inventive method for determining a suitable parking space for a vehicle using sensors for measuring gaps between objects detected laterally by the vehicle, the sensors for measuring gaps between objects detected laterally by the vehicle are activated both to the right and left of the vehicle. The signals from these sensors are evaluated in such a way that, by comparing the information obtained from the signals with predefined patterns in the form of a temporal sequence of relative maxima and minima with their change over time or over a defined distance, it is determined whether the objects detected on the right and left sides of the vehicle are stationary or moving longitudinally. A predefined pattern can, for example, include the temporal change of a sensor signal, which allows the size and movement of objects on neighboring tracks to be detected. Preferably, the sensors are activated or remain activated when the vehicle speed is below a predefined threshold. Particularly when the vehicle is stationary or traveling at very low speeds, it should be easiest to determine whether the objects detected on the right and left sides of the vehicle are stationary or moving longitudinally. It is irrelevant whether the vehicle is moving forwards or backwards. The sensors can be switched on independently of a manual activation of the parking space measurement, so that a side selection could already have been made when the parking space measurement is manually activated. In this case, a suitable parking space will only be displayed to the driver if a sufficiently large space has been detected on the side of the vehicle where previously stationary objects were identified. If, otherwise, a sufficiently large gap is detected on one side of the vehicle and it has not yet been determined that objects are stationary on that side, the sensors remain activated and the driver is prompted to brake. This can also occur indirectly, for example, by at least temporarily displaying a suitable parking space. At the latest after the vehicle falls below a predefined speed, preferably when stationary or rolling very slowly forward or backward, it is determined whether objects are stationary on that side of the vehicle. If not, the driver is prompted again, directly or indirectly, to continue driving. The invention achieves a plausibility check of detected parking spaces on both sides of a vehicle without additional sensors. This suppresses the display of unsuitable parking spaces. Of course, the driver ultimately retains the final choice of the appropriate parking space, for example, by activating the automatic parking assist to accept the space or continuing to drive to decline it. An embodiment of the invention is described in more detail below: An ultrasonic sensor, similar to that used in PDC (Park Distance Control) systems, measures the depth of parking spaces along the y-axis as the vehicle drives past them. The depth is calculated from the wheel speed data. When the parking space measurement system is used in conjunction with a parking assistant, the control unit calculates a trajectory along which the car, at the driver's request, automatically reverses into the space using electronic steering assistance. Longitudinal steering remains under the driver's control. This existing ultrasonic sensor technology can only provide the distance perpendicular to the direction of travel (y-axis of the vehicle) to objects (currently a maximum of approximately 3 to 5 objects) in the measurement direction, for example, the curb as a lateral road boundary and the front edge of a parked vehicle. Alternative sensor principles, such as radar sensors or optical distance sensors based on triangulation or time-of-flight measurement, would be too complex and expensive for this application. The most cost-effective solution today is a PDC sensor with improved measuring range and signal dynamics. For example, below a predefined vehicle speed threshold, sensibly below approximately 40 km / h in urban traffic, parking spaces are searched for on both sides of the road; that is, the sensors are automatically activated. Suitable parking spaces detected in the past are only displayed to the driver after they have activated the parking assistant via a designated control. Alternatively, spaces can also be searched for on both sides of the road after the driver has manually activated the parking assistant. Once a sufficiently large parking space is detected, the driver is notified. The direction of the detected space (left or right) can be displayed. In principle, a search on both sides is also possible in one-way streets. After the message "Space detected" and confirmation by the driver, e.g.,By stopping and engaging reverse gear or by manually confirming via the control provided for this purpose, the car parks itself automatically in the parallel parking space in the usual manner. When passing a parking space, the sensor ideally provides a rectangular contour; for example, a distance of 0.5 m to a parked vehicle, then 2.5 m to the curb, then another 0.5 m to a second vehicle ahead. Longitudinal information comes from the wheel speed sensors. This x / y contour (approximately a rectangular area roughly parallel to the roadway) is interpreted as a parking space, and once the vehicle has come to a standstill and a defined starting position is reached, the trajectory for parking is calculated. In urban traffic on multi-lane roads, it's possible that, for example, there are actual parking spaces on the right, while on the left there is slow-moving parallel traffic. In such cases, there's a risk that, under unfavorable conditions involving vehicle lengths and relative speeds, the signal from the left sensor might indicate a parking space that doesn't actually exist. This is because, by its very nature, the ultrasonic sensor cannot detect the movement of objects along the length of the road (i.e., traffic traveling in or against the direction of travel). However, by measuring the relative speed of objects located to the side relative to the vehicle's speed in the x-direction, even at higher vehicle speeds, it's possible to easily distinguish between actual parking spaces and gaps in the flow of traffic.A combination of ultrasonic sensors for measuring parking space depth with the signal from a sensor capable of detecting relative movement of the detected objects in the x-direction would therefore be advantageous. This would reveal whether the vehicles are stationary or in a moving line. In this way, detected gaps can be validated. Suitable sensors for this purpose include those already used in vehicles: radar sensors that cover the lane behind, as in systems for overtaking warnings or rear-view monitoring, or cameras that provide all-around visibility and can also utilize their information to detect slow-moving traffic. A rough estimate is possible even at night by comparing the size of prominent points in the captured images. However, these additional sensors for measuring relative speed are expensive.The use of current PDC sensors that are angled outwards is of little use due to their small measuring range and the lack of angular information. According to the invention, the parking space measurement sensors are used multifunctionally to measure the parking space and to select a suitable side, or to validate the detected space as a suitable parking space. The sensor on the side where the space was detected continues to operate – preferably when the vehicle is stationary, but also when rolling forward or backward. If there are stationary objects on that side, the distance signal or the signal pattern in the lateral direction remains approximately the same or hardly changes, at least when the vehicle is stationary or moving very slowly. If there is a line of vehicles in the adjacent lane, a characteristic signal pattern in an approximate rectangular shape with pronounced maxima and minima can be observed, depending on the relative speed of the other vehicles to the vehicle in question.Here, the sensor signals are validated with regard to the differentiation between stationary and moving objects, as well as between narrow (traffic signs, pedestrians) and wider (vehicle) objects. The acquired sensor signals are preferably stored in a ring buffer for a defined distance for comparison with predefined patterns. For example, if the pattern derived from the acquired sensor signals, in the form of a temporal sequence of maxima and minima, changes significantly when switching from forward to reverse travel, this indicates moving objects, such as a line of vehicles in the adjacent lane. Filtering the raw sensor signals with a suitable time constant prevents a noisy sensor signal from being evaluated as a rapid succession of passing objects. Pedestrians moving perpendicular to the vehicle are identifiable as such from the path signal of the ultrasonic sensor and are taken into account in the evaluation. The drawing schematically illustrates a possible situation for the described embodiment. The drawing shows three parallel lanes. Objects, particularly vehicles, are represented as rectangles. Three vehicles are parked in the lower lane (v=0). In the middle lane, the vehicle using the inventive method is stationary or rolling slowly (v≈0) and detects objects on the left and right sides within the measuring range MB using ultrasonic sensors. The inventive method generates a signal pattern M1 for the right side of the vehicle and a signal pattern M2 for the left side over time t or a distance x. Signal pattern M1 remains essentially constant and thus indicates parked vehicles on the right side. Signal pattern M2 changes over time t or distance x and indicates a moving convoy on the left side.According to the invention, in this situation, only a sufficiently large gap detected on the right side of the vehicle is displayed as a suitable parking space. The parking assistant can also be combined with a navigation system. Based on the road type stored in the navigation system and its own data, it can be verified whether the detected parking spaces could actually be located there. For example, spaces detected on the left side of a two-lane highway, taking into account the measurement range and lane width, might only be represented by a line of cars in the parallel lane. Navigation data can also prevent the system from mistaking an intersection for a parking space. Displaying parking spaces in a bus bay is also avoided this way. Furthermore, a basic prioritization of the likely "correct" side of the road for suitable parking spaces could be made based on the country code (left-hand traffic, right-hand traffic).

Claims

Method for determining a suitable parking space for a vehicle using sensors for measuring gaps between objects detected laterally by the vehicle, wherein the sensors for measuring gaps between objects detected laterally by the vehicle are activated both to the right and to the left of the vehicle, characterized in that the signals of these sensors are evaluated in such a way that, by comparing information obtained from the signals with predefined patterns (M1, M2) in the form of a temporal sequence of relative maxima and minima with their change over time or over a defined distance, it is determined whether the objects detected on the right and left sides of the vehicle are stationary or moving longitudinally. Method according to claim 1, characterized in that the sensors are activated or remain activated when the vehicle speed (v) is less than a predetermined threshold. Method according to one of the preceding patent claims, characterized in that the sensors are switched on independently of a manual activation of the parking space measurement. Method according to one of the preceding patent claims, characterized in that a suitable parking space is only displayed to the driver if a sufficiently large space has been detected on a side of the vehicle on which previously stationary objects were detected. Method according to one of the preceding claims, characterized in that - if a sufficiently large gap on one side of the vehicle has been detected and it has not yet been determined that the objects are standing on that side of the vehicle - the sensors remain activated and the driver is prompted to brake the vehicle, after which it is determined at the latest after falling below the (one) predetermined vehicle speed whether the objects are standing on that side of the vehicle. Method according to one of the preceding claims, characterized in that the detected sensor signals are stored for comparison with predetermined patterns (M1, M2), preferably in a ring buffer, with reference to a defined distance (x).

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