DE102011080931A1 - Method for calibrating rolling circumference of tire of motor vehicle, involves detecting environment side next to motor vehicle during ride for recording of delineator, and detecting number of revolutions of wheels on route - Google Patents

Abstract

The method involves detecting the environment side next to the motor vehicle (1) during the ride for recording of delineator (7), and detecting the number of revolutions of the wheels of the motor vehicle on the route between two detected delineators. The rolling circumference of the quotient from the desired distance of the delineator and the number of revolutions of the wheels is determined. The number of revolutions on the route between a predetermined number of delineators is detected. The average value is applied for determination of the rolling circumference of the wheel. An independent claim is included for a device for calibrating the rolling circumferences of a tire of a motor vehicle.

Description

State of the art

The invention relates to a method for calibrating the rolling circumferences of the tires of a motor vehicle. The invention further relates to a device for carrying out the method.

For a number of functions of driver assistance systems, it is necessary to obtain precise information about the location of an object and its own motor vehicle movement. This is especially necessary for assisted parking maneuvers or even maneuvers in close proximity.

The motor vehicle movement is usually determined by wheel pulse counters. For this purpose, however, it is necessary to know the exact route traveled by the motor vehicle between two successive detected wheel pulses. A precise value for the distance traveled is only obtained if the exact wheel circumference is known. However, the wheel circumference may be e.g. change significantly when changing wheels. An error in Reifenabrollumfang from which the route length is determined, especially in Rangiermanövern or Einparkmanövern lead to a position error. With such a position error, the collision probability to an object increases significantly. Furthermore, sloping park end positions are often possible. In particular, when supported Längeinparken the Tuschieren the curb is possible due to incorrect route calculation. Also, inappropriate expenses to the driver may be due to model errors between reality and the internal model.

To minimize the error, it is necessary to determine the tire rolling circumference. This is for example off DE 10 2007 029 870 A1 Known to evaluate wheel speed signals and signals from at least one sensor for measuring the speed of the motor vehicle on the ground. From the speed measurement and the evaluation of the wheel speed signals is closed to the Reifenabrollumfang. The system is used to monitor the tire condition.

Disclosure of the invention

Advantages of the invention

• (a) Erfassen der Umgebung seitlich neben dem Kraftfahrzeug während der Fahrt zur Erfassung von Leitpfosten,
• (b) Erfassen der Anzahl der Umdrehungen der Räder des Kraftfahrzeugs auf der Strecke zwischen zwei in Schritt (a) erfassten Leitpfosten,
• (c) Bestimmung des Abrollumfangs aus dem Quotienten aus dem Sollabstand der Leitpfosten und der Anzahl der Umdrehungen der Räder.

The method proposed according to the invention for calibrating the rolling circumferences of the tires of a motor vehicle comprises the following steps:

• (a) detecting the surroundings laterally next to the motor vehicle while driving to detect guide posts,
• (b) detecting the number of revolutions of the wheels of the motor vehicle on the route between two guide posts detected in step (a),
• (c) determining the rolling circumference from the quotient of the nominal distance of the guide posts and the number of revolutions of the wheels.

By the method according to the invention, it is possible in a simple manner to calibrate the tire rolling circumference since the guide posts used always have a prescribed distance. The guide posts can be easily detected with existing driver assistance system with the sensors already installed on the motor vehicle.

In order to compensate for inaccuracies in the distance between two guide posts, it is preferable if the number of revolutions on a route between a predetermined number of guide posts is detected. The number of guide posts is preferably above two. The number of guide posts is preferably more than five, in particular preferably more than ten, in order to be able to identify possible inaccuracies.

Alternatively, it is also possible to repeat the steps (a) and (b) several times, to form an average of the detected number of revolutions of the wheels and to use the mean value for determining the rolling circumference of the wheels. In this case too, the averaging compensates for a possible error due to deviations in the distances between the guide posts. The larger the number of measurements, the smaller the resulting error will be.

It is possible to use the nominal distance of the guide posts since the guide posts are usually set up at a distance of 50 m from one another. Alternatively, deviating distances of 50 m are possible, for example 30 m or 40 m. The distances are given in each case. In order to determine the actual desired distance of the guide posts, it is possible to detect the number of revolutions of the wheels between two detected guide posts and to multiply it by a known tire circumference. The known tire circumference may be the tire circumference, which is provided on the basis of the predefined tire size for the motor vehicle. In the case of a deviation of the calculated value from a predefined setpoint distance, the nominal distance closest to the calculated value is used as the setpoint distance for calibrating the tire rolling circumference.

Especially at junctions and in curves usually occur varying distances of the delineator posts. In this case, in the Generally, a large deviation from the set point can be measured. Here, it is possible to either turn off to the nearest predetermined target distance to determine the tire rolling circumference, but it is preferable to repeat the determination of the target distance in such a measurement and to ignore the value with the strong deviation.

In the case of a deviation between the nominal distance of the guide posts and the determined distance of the guide posts, it is preferable to use the predetermined desired distance closest to the specific distance as the desired distance in step (c). In addition to an inaccuracy in setting the guide post and thus a deviation in the distance of the guide post, it is also possible that the error in the determination of the distance results from the fact that the rolling circumference of the tire is incorrectly predetermined. The actual rolling circumference of the tire is then determined by the method according to the invention. This can then be used in the further course for the implementation of the driver-assisting functions of a driver assistance system.

In order to minimize errors in the detection of the guide posts with the sensors used for detection, it is furthermore preferred if at least two sensors are used for detecting the guide posts. By measuring with two sensors, measuring errors of a sensor can be detected and thereby eliminated.

A device according to the invention for carrying out the method preferably comprises at least one sensor for detecting the surroundings laterally next to the motor vehicle, means for evaluating whether delineators have been detected, means for detecting the number of revolutions of the wheels and evaluation means for determining the tire rolling circumference from the number of revolutions the wheels and the distance between two guide posts.

As a sensor for detecting the environment laterally next to the motor vehicle, any, known in the art sensor can be used, which is suitable for detecting the environment of a motor vehicle. Generally used sensors are, for example, ultrasonic sensors, infrared sensors, radar sensors, lidar sensors or optical sensors such as cameras.

When an ultrasonic sensor, an infrared sensor, a radar sensor or a lidar sensor is used, a signal from the sensor is emitted to detect the environment, which is reflected by a detected object. An echo generated in this way is detected by a receiver and from the detected signal it is possible to deduce the distance and the shape of an object. Since a guide post has a characteristic shape, it is possible to recognize, by evaluating the acquired data, whether a detected object is a guide post.

When optical sensors, such as cameras are used to capture the environment laterally adjacent to the motor vehicle, preferably an image processing is used to evaluate the captured images and examined on guide posts. Here too, the characteristic appearance of the guide post makes it possible to search for a specific structure in the captured image and in this way to recognize the guide post. In order to establish an exact distance between two guide posts, it is necessary to take several measurements in succession and to start and stop the measurement of the number of wheel revolutions each time a guide post is detected at the same position. This ensures that the exact distance between two guide posts is used for evaluation.

If several sensors are used, for example to rule out incorrect measurements with the sensors, it is particularly preferred if different sensor types are used for the measurement. For example, it is possible to use an ultrasonic sensor and an optical sensor or a lidar sensor and an optical sensor or even an ultrasonic sensor and a radar sensor. Any other combination of sensor types is possible.

As means for evaluating whether guide posts have been detected and evaluation means for determining the tire circumference from the number of revolutions of the wheels and the distance between two guide posts, for example a control device of the motor vehicle or an on-board computer can be used. The on-board computer or the control unit is provided in this case with a corresponding computer program with which the method can be performed and with which the acquired data can be evaluated.

The possible nominal distances between two guide posts are preferably stored in a storage medium, which can be accessed by the evaluation means for determining the tire circumference. The storage means may be a non-writable or a rewritable storage means. Any storage means known to a person skilled in the art can be used on which data can be stored and which can be accessed by the control unit or the on-board computer.

As a means for detecting the number of revolutions of the wheels Radimpulssensoren are commonly used. The data of Radimpulsensoren are then also supplied to the evaluation, so that from the data detected by the Radimpulszählern and the target distance between two Leitpostosten the Reifenabrollumfang can be determined.

Brief description of the drawings

Embodiments of the invention are illustrated in the figures and are explained in more detail in the following description.

Show it:

1 A schematic plan view of a motor vehicle for detecting guide posts,

2 A motor vehicle in side view when carrying out the method according to the invention.

Embodiment of the invention

In 1 is schematically illustrated a motor vehicle in plan view in carrying out the method according to the invention.

A motor vehicle 1 is with sensors 3 equipped with which the environment of the motor vehicle can be detected. This is done by the sensors 3 a signal 5 sent by objects within the radiation range of the signal 5 is reflected. The reflected echo is from a receiver of the sensor 3 can be received and from the duration of the signal can be deduced the distance to the object. When using at least two transmitters or at least two receivers which are spaced apart from each other, the direction of the object can additionally be determined. If an optical sensor, for example a camera, is used, the received image can be selected with suitable image processing for detecting the objects.

For the inventive method for calibration of Reifenabrollumfangs is using the sensors 3 the environment laterally next to the vehicle 1 captured to guide posts while driving 7 to detect.

To calibrate the Reifenabrollumfangs the number of revolutions of a wheel is counted, which requires the wheel until the motor vehicle 1 the distance between two delineators 7 has covered. Because the distance of the delineator posts 7 is given, can from the distance of the delineator posts 7 and the number of revolutions are closed to the Reifenabrollumfang. In order to determine the number of revolutions of the wheel, the measurement is preferably started when a guide post 7 is detected by a sensor and ends when a second guide post 7 from the same sensor 3 is detected. In order to rule out possible measurement errors, it is still possible to repeat several measurements and to form an average of the measured results. Alternatively, it is also possible, not two adjacent delineators 7 as start and end point to choose but two farther apart and the corresponding number of guide posts also to determine the route length.

Another source of error can be excluded if more than one sensor 3 is used for detecting the environment of the motor vehicle. It is possible, for example, sensors in the front and rear of the vehicle 1 to use. Furthermore, it is advantageous if multiple sensors 3 be used to use different types of sensors. As sensors, for example, as already mentioned above, ultrasonic sensors, infrared sensors, radar sensors, lidar sensors or optical sensors can be used. For example, when different types of sensors are used, it is possible to use ultrasonic sensors and radar sensors or ultrasonic sensors and optical sensors. Any other sensor combination is conceivable.

The sensors that are inserted around the delineators 7 In this case, it is preferable to detect sensors which can also be used for other driver assistance systems, for example for detecting surroundings for a parking assistance system.

In 2 is a motor vehicle for carrying out the method according to the invention in a side view.

While the motor vehicle 1 on a street 9 that drives with guide posts 7 is limited, the environment of the motor vehicle 1 from sensors 3 detected. The captured environment will be on guide posts 7 evaluated. Once a first guidepost 7 is detected, starts the measurement and the revolutions of at least one wheel 11 of the motor vehicle 1 are counted. Preference is given to the revolutions of all wheels 11 of the motor vehicle 1 counted. As soon as the sensor 3 a second guidepost 7 detected, the measurement is terminated. As already described above, the distance between the two guide posts becomes 7 and the number of revolutions of the wheels 11 the tire rolling circumference is determined. The Reifenabrollumfang results from the distance of the guide post divided by the number of Radumdrehungen.

To detect the revolutions of the wheels is usually a Radimpulszähler 13 used.

To determine the tire rolling amount, the wheel pulse counter data becomes 13 and the environmental data of the sensors with which the guide posts 7 be detected, supplied to a control unit of a suitable driver assistance system or on-board computer and evaluated with this. In order to eliminate possible measurement errors, it is preferable to perform several measurements and average the results obtained. Alternatively, it is also possible to measure over a longer distance than just the distance between two adjacent guide posts in order to minimize corresponding errors. Furthermore, as already described above, it is advantageous if a plurality of sensors, for example also different sensors, are used to detect the guide posts.

The distance between two delineators is specified by law and is usually 50 m. However, it is also possible, for example at junctions or in curves, that the distance of the guide posts from the 50 m deviates. Here, the distance is usually divisible by ten or by five. To measure the distance between two guide posts, multiply the measured number of revolutions of the wheel between two guide posts by a known wheel circumference. Since the wheel circumference does not have to correspond exactly to the actual tire rolling circumference, the value obtained may differ from the actual distance between the two guide posts, which is for example 50 m, 40 m or 30 m. In this case, the closest predetermined distance is chosen as the distance between the guide posts. The predetermined distances between the guide posts are preferably stored in a memory of the control unit. These data can then be used for evaluation to determine the tire rolling circumference.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102007029870 A1 [0004]

Claims (11)

Method for calibrating the rolling circumferences of the tires of a motor vehicle ( 1 ), comprising the following steps: (a) detecting the environment laterally next to the motor vehicle ( 1 ) while driving to detect delineators ( 7 ), (b) detecting the number of revolutions of the wheels ( 11 ) of the motor vehicle ( 1 ) on the route between two guide posts detected in step (a) ( 7 ), (c) determining the rolling circumference from the quotient of the nominal distance of the guide posts ( 7 ) and the number of revolutions of the wheels ( 11 ). A method according to claim 1, characterized in that the number of revolutions on a route between a predetermined number of guide posts ( 7 ) is detected. Method according to claim 1, characterized in that the steps (a) and (b) are repeated several times, an average of the detected number of revolutions of the wheels ( 11 ) and for determining the rolling circumference of the wheels ( 11 ) the average value is used. Method according to one of claims 1 to 3, characterized in that for determining the nominal distance of the guide posts ( 7 ) the number of revolutions of the wheels ( 11 ) between two detected guide posts ( 7 ) and multiplied by a known tire circumference. A method according to claim 4, characterized in that in case of a deviation between the desired distance and a certain distance of the guide post ( 7 ) the predetermined distance closest to the given distance is used as the desired distance in step (c). Method according to one of claims 1 to 5, characterized in that at least two sensors ( 3 ) to record the guide posts ( 7 ) are used. Apparatus for carrying out the method according to one of claims 1 to 6, comprising at least one sensor ( 3 ) for detecting the environment laterally next to the motor vehicle ( 1 ), Means for evaluating whether delineators ( 7 ) means for detecting the number of revolutions of the wheels ( 11 ) and evaluation means for determining the tire rolling circumference from the number of revolutions of the wheels ( 11 ) and the distance between two guide posts ( 7 ). Device according to claim 7, characterized in that the at least one sensor ( 3 ) for detecting the environment laterally next to the motor vehicle ( 1 ) is an ultrasonic sensor, an infrared sensor, a radar sensor, a LIDAR sensor or an optical sensor. Apparatus according to claim 7 or 8, characterized in that when using a plurality of sensors ( 3 ) different sensor types are used. Device according to one of claims 7 to 9, characterized in that the possible nominal distances between two guide posts ( 7 ) are stored in a storage medium, which can be accessed by the evaluation means for determining the tire rolling circumference. Device according to one of claims 7 to 10, characterized in that the means for evaluation and the evaluation means comprise a control device of the motor vehicle or an on-board computer.

Images