Procedure for determining a suitable parking space

Abstract

Method for determining a suitable parking space for a vehicle by means of sensors for measuring gaps between objects detected to the side of the vehicle, in which the sensors for measuring gaps between objects detected to the side of the vehicle can be activated both to the right and to the left of the vehicle, characterized in that when the vehicle (1) is at a standstill (S0) it is checked whether the signals from the sensors change during the standstill and the detection of a suitable parking space or an incipient parking space is rejected as invalid only for a defined distance (S) after the standstill (S0) if the signals from the sensors on this side of the vehicle have changed during the previous standstill of the vehicle (1).

Description

The invention relates to a method for determining a suitable parking space according to the preamble of claim 1.Such a process is described, for example, in the German patent application DE 10 2006 036 423 A1, which is not prepublished. This method is concerned in particular with the fact that it is determined by means of the sensors of the own vehicle during travel whether the objects detected on the right or left side of the vehicle are standing or are moving.To assist the driver of a vehicle in a parking space search, many automatic parking space surveying systems are already known which determine the length and the depth of a possible parking space. The driver is indicated whether his vehicle fits into the parking space. This function is conceivable for both the right and left sides of the road. However, it is only expedient to use the function if the driver actually wishes to shut down his vehicle. Therefore, the parking space surveying is usually manually activated by a user.In addition, a page selection is to be made. It is known to evaluate the operation of the driver of the vehicle by the turn signal. An additional switch for page selection would be possible, but too expensive.DE 102 58 310 A1 discloses a method for determining a suitable parking space, in which a side selection is carried out by determining the oncoming traffic via a radar unit.EP 0 936 471 A2 discloses a vehicle having an object detection device for detecting objects in a laterally rearward observation area, which includes means for contactless, radiation-based scanning of the observation area and an evaluation unit connected downstream of the scanning means. The evaluation unit distinguishes objects moving in the direction of travel of the vehicle from stationary and oncoming objects on the basis of a response sequence of observation subareas.Furthermore, DE 10 2007 002 738 A1 describes a method for supporting a parking process of a vehicle having at least one sensor into a parking space arranged laterally with respect to the vehicle, wherein the parking space and a distance from an object are detected by means of the sensors during a passing. In this case, the objects located in the environment of the vehicle can be distinguished with regard to their state of movement. Thus, for example, the flowing traffic can be hidden.It is an object of the invention to further improve the method of the type mentioned at the beginning with regard to the prevention of erroneous detections.This object is achieved according to the invention by the subject matter of claim 1. Advantageous further developments are the subject matter of the dependent patent claims.In the method according to the invention for determining a suitable parking space for a vehicle by means of sensors for measuring gaps between objects detected laterally by the vehicle, in which the sensors for measuring gaps between objects detected laterally by the vehicle can be activated both on the right and on the left of the vehicle, it is checked when the host vehicle is at a standstill whether the signals of the sensors change during the standstill. A suitable parking space is therefore understood here to be a free area which is not only large enough for the host vehicle, but which is also not detected in particular on an adjacent roadway.When the host vehicle continues to drive after a standstill, the detection of a suitable parking space or an beginning parking space on one side of the vehicle is discarded as invalid if the signals of the sensors on this side of the vehicle have changed during the preceding standstill of the host vehicle, since objects (in particular vehicles) passing by them are detected and the probability is therefore great that the adjacent free region is not a parking lane but rather a driving lane. In this case, the detection of a suitable parking space or of a starting parking space is discarded as invalid only for a defined distance after standstill. The defined route can be, for example, in the city area in the range of 10 to 40 meters. The route can optionally also be predefined depending on the environment. The defined route is generally designed such that a roadway change, such as the end of a turn lane and a parking lane adjoining it, is possible again thereafter.In an advantageous development of the invention, a change threshold is predefined for detecting a change in the signals of the sensors during standstill, which change threshold has to be exceeded. The change threshold is predefined in such a way that a moving object is reliably present when the change threshold is exceeded.An exemplary embodiment of the invention is described in more detail below:An ultrasonic sensor similar to the PDC (Park Distance Control) sensor system with a measurement direction in the y-axis measures its depth when passing by parking spaces. The length is calculated from the wheel speed information. When using the parking space surveying system in connection with a parking assistant, a trajectory is calculated in the control device, on which trajectory the car, if the driver wishes, autonomously maneuvers back into the gap under the control of an electronic steering aid. The longitudinal guidance is still left to the driver.This already known ultrasonic sensor system can only provide the distance transversely to the direction of travel (y-axis of the vehicle) to objects (currently at most approximately 3 to 5 objects) in the measurement direction, for example the curbstone as a lateral roadway boundary and the front boundary edge of a parked vehicle. Alternative sensor principles, such as radar sensors or optical distance sensors based on triangulation or time-of-flight measurement, are currently expensive and expensive for this purpose of use. The cost-optimum solution is today a PDC sensor which is improved with regard to measurement range size and signal dynamics.For example, below a predefined vehicle speed threshold, meaningfully in city traffic in a range below approximately 40 km / h, parking spaces are sought on both sides; i.e., the sensors are automatically switched on. Recognized suitable parking spaces as results that are earlier in time are only displayed to the driver after he has also activated the parking assistant via an operating element provided for this purpose. Alternatively, gaps can also be sought on both sides after manual activation of the parking assistant by the driver. After a sufficiently large parking space has been detected, the driver is alerted. The direction of the detected gap (left or right) may be displayed. In principle, a search on both sides can therefore also be possible in one-way roads. After the message "gap detected" and confirmation of the driver, for example by stopping and engaging the reverse gear or by manual confirmation via the control element provided for this purpose, the car parks in the parallel parking gap automatically in a known manner.When driving past a parking space, the sensor ideally delivers a rectangular contour; for example, distance 0.5 m from a parked vehicle, then distance 2.5 m from the curbstone, then again 0.5 m from a second vehicle in front. The longitudinal information comes from the wheel speed sensors. This x / y contour (approximately a rectangular surface in an approximately parallel alignment along the roadway) is interpreted as a parking space and, for this purpose, the trajectory for parking is calculated after a defined starting position is reached when the vehicle is stationary.In city traffic in multi-lane roads, it is possible that real gaps are present, for example, on the right, but in parallel traffic is present on the left. There is the risk here that, in the case of unfavourable constellations of vehicle lengths and relative speed, a parking space results in the signal of the left sensor, which is not actually present. This is because the ultrasonic sensor cannot basically detect a movement of the objects in the roadway longitudinal direction (i.e., traffic in or opposite to its own direction of travel) due to the principle. The detection of the relative speed of objects laterally in the vicinity to the own travel speed in the x-direction of the vehicle makes it possible to easily distinguish between real parking spaces and gaps in the moving traffic even at higher vehicle speeds. A combination of the ultrasonic sensors for measuring the parking space depth with the signal of a sensor which can detect a relative movement of the detected objects in the x direction would therefore be advantageous. It would be apparent from this whether it is stationary traffic or a moving vehicle queue. Thus, detected gaps can be checked for plausibility. For this purpose, the following sensors, for example, are suitable, which are already provided today for applications in vehicles: radar sensors which cover the lane to the rear, as in systems for passing warning or rear space monitoring, or radar sensors which, in the context of distance-related vehicle speed systems (ACC), also emit to the front, or cameras, by means of which, with all-round vision, their information can also be used for detecting slow-moving columns. By comparing the sizes of prominent points of the captured images, a rough estimation is possible even at night. However, these additional sensors for detecting the relative speed are expensive. The use of current PDC sensors, which are directed obliquely outwards, is not very useful because of their small measurement range and because of the lack of angle information.Preferably, therefore, by multifunctional use of the parking space measurement sensors, firstly the parking space is measured and secondly a side selection is made or the detected gap is checked for plausibility as a suitable parking space. The sensor, on the side of which the gap was detected, continues to be operated-preferably when the vehicle is at a standstill or else when rolling out forwards or when rolling back. If stationary objects are involved on this side, the distance signal or the signal pattern remains approximately the same or hardly changes in the transverse direction at least when the own vehicle is stationary or when it is moving very slowly. When a vehicle coil is travelling in the adjacent lane, a characteristic signal pattern in an approximate rectangular shape with marked maxima and minima can be recognized depending on the relative speed of the other vehicles to the own vehicle. Here, the sensor signals are checked for plausibility with regard to the differentiation between stationary and moving objects and also between narrow (traffic signs, pedestrians) and wider (vehicle) objects.For comparison with predetermined patterns, the detected sensor signals are preferably stored in a ring memory for a defined route. If, for example, the pattern determined from the detected sensor signals changes significantly in the form of a temporal sequence of maxima and minima when a change from forward travel to reverse travel, this is an indication of moving objects, such as a rolling platoon of vehicles on the adjacent lane.For this exemplary embodiment, reference is made in full to German patent application DE 10 2006 036 423 A1, the subject matter of which can be combined advantageously with the invention described here.The drawing shows particular problem situations with respect to the above-described exemplary embodiment, which are taken into account by the method according to the invention. It shows FIG. 1 ashows a first initial situation in which a foreign vehicle enters the detection area of the own stationary vehicle, FIG. 1 bshows a parking space misdetection when the host vehicle travels faster after standstill than the other vehicle after the first initial situation, FIG. 1 cshows a parking space misdetection when the host vehicle travels more slowly after standstill than the other vehicle after the first initial situation, FIG. 2 ashows a second initial situation, in which a foreign vehicle leaves the detection area of the own stationary vehicle, FIG. 2 bshows a parking space misdetection when the host vehicle travels faster after standstill than the other vehicle after the second initial situation, and FIG. 2 cshows a parking space misdetection when the host vehicle travels more slowly after standstill than the other vehicle after the second initial situation.All FIGS. 1a to 2c show two parallel roadway tracks. Objects, in particular in the form of vehicles, are represented as rectangles. In the respective lane shown above, the host vehicle 1 is shown with a control device (not shown in detail here) for carrying out the method according to the invention. In the lower lane in each case, a different vehicle 2 is shown. The vehicle speed of the own vehicle 1 is abbreviated as v 1, and the vehicle speed of the other vehicle 2 is abbreviated as v 2.For simplicity, the own vehicle 1 is only shown with a sensor on the right side by means of a wedge-shaped measurement range MB. By means of this sensor, which can be a simple distance sensor, the distance to the closest object is measured in the y direction of the own vehicle 1 and it is assessed whether a parking space with sufficient depth could be present. There are many known evaluation methods for this. According to the invention, it is determined whether a free area-in this case on the right adjacent lane-can also actually be a parking space in a parking lane or merely a free area between currently undetected vehicles (or other objects) on a roadway.For this purpose, according to the invention, when the host vehicle 1 is at a standstill, which is shown with the start S 0 of a route x following it, a signal change (see arrows in or against the y direction) of the sensor is detected, from which it can be seen that, at least with great probability, a host vehicle 2 has moved either into the measurement region MB (FIG. 1 a ) or out of the measurement region MB (FIG. 2 a ).Among FIGS. 1a to 2c, the respective signal changes are schematically shown as y-levels over time t. At the time t0, a signal change is respectively detected for the two initial situations at standstill S0, from which it is concluded that the adjacent lane is indeed a driving lane and thus there is no suitable parking space, even if a sufficiently large free area would be detected.According to FIG. 1 b, a parking space misdetection would follow without the invention if the host vehicle 1 travels faster after standstill S 0 (v1>v2) than the host vehicle 2 after the first initial situation.According to FIG. 1 c, a parking space misdetection would follow without the invention if the host vehicle 1 travels more slowly after standstill S 0 (v 1<v 2) than the host vehicle 2 after the first initial situation.According to FIG. 2 b, a parking space misdetection would follow without the invention if the host vehicle 1 travels faster after standstill S 0 (v1>v2) than the host vehicle 2 after the second initial situation.According to FIG. 2 c, a parking space misdetection would follow without the invention if the host vehicle 1 travels more slowly after standstill S 0 (v 1<v 2) than the host vehicle 2 after the second initial situation.Therefore, according to the invention, at standstill S 0 of the own vehicle 1, it is checked whether the signals of the sensors change during standstill S 0. During continued travel after standstill S 0 of the own vehicle 1, the detection of a suitable parking space or of a starting parking space on one vehicle side is discarded as invalid if the signals of the sensors on this vehicle side have changed during the preceding standstill of the own vehicle 1. The recognition of a suitable parking space or of an beginning parking space is preferably discarded as invalid only for a defined distance S after standstill S 0.

Claims

Method for determining a suitable parking space for a vehicle by means of sensors for measuring gaps between objects detected laterally by the vehicle, in which the sensors for measuring gaps between objects detected laterally by the vehicle can be activated both on the right and on the left of the vehicle, characterized in that, when the own vehicle (1) is at a standstill (S0), it is checked whether the signals of the sensors change during the standstill and the detection of a suitable parking space or of a starting parking space is discarded as invalid only for a defined distance (S) after the standstill (S0) if the signals of the sensors on this vehicle side have changed during the preceding standstill of the own vehicle (1).Method according to claim 1, characterised in that a predetermined change threshold has to be exceeded for the detection of a change in the signals of the sensors during standstill.

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