Motor vehicle having occlusion detection for ultrasonic sensors

Patent metadata

Field	Value
Publication number	US-10094923-B2
Application number	US-201415036344-A
Country	US
Kind code	B2
Filing date	Oct 30, 2014
Priority date	Nov 14, 2013
Publication date	Oct 9, 2018
Grant date	Oct 9, 2018

Abstract

In a method for checking a first ultrasonic sensor of a motor vehicle for an occlusion, a measuring signal of the first ultrasonic sensor is acquired by an evaluation unit, and from the measuring signal, a decay time of a natural oscillation of the diaphragm of the first ultrasonic sensor, brought about by an excitation pulse, is ascertained. From the measuring signal of either the first ultrasonic sensor or a second ultrasonic sensor, an echo produced by an object located in a sensing range of the first ultrasonic sensor is ascertained, and a distance value of the object is determined on the basis of the echo. An occlusion is signaled if the decay time is less than a predetermined threshold value which would be exceeded if ice and/or dirt were to adhere directly to the diaphragm, and if the distance value is less than a predetermined maximum value.

First claim

What is claimed is:

1. A method for checking a first ultrasonic sensor of a motor vehicle for an occlusion, the method comprising:
applying, by a transmitter unit, an excitation pulse to a diaphragm of the first ultrasonic sensor;
detecting, by an evaluation unit, a measuring signal of the first ultrasonic sensor, and ascertaining from the measuring signal a decay time of a natural oscillation of the diaphragm, brought about by the excitation pulse;
ascertaining, from one of the measuring signal of the first ultrasonic sensor or a measuring signal of a second ultrasonic sensor, an echo of the excitation pulse, produced by an object located in a sensing range of the first ultrasonic sensor, and determining at least a first distance value of the object on the basis of the echo; and
signaling, by the evaluation unit, an existence of the occlusion at least if (i) the decay time is less than a predetermined threshold value, and (ii) the first distance value is less than a predetermined maximum value, wherein the predetermined threshold value represents a value which is exceeded in the event at least one of ice and dirt is adhered directly to the diaphragm.

2. The method as recited in claim 1 , wherein the occlusion is also signaled if the motor vehicle is stationary during the ascertainment of the decay time and the at least first distance value.

3. The method as recited in claim 1 , wherein at least one second distance value of the object is ascertained, and a change in distance to the object is determined on the basis of the first and second distance values, and a distance traveled by the motor vehicle is determined on the basis of a movement of the motor vehicle, and during the movement of the motor vehicle, the occlusion is only signaled if the change in the distance to the object is less than the distance traveled by the motor vehicle.

4. The method as recited in claim 1 , wherein:
based on the at least first distance value, the evaluation unit enters a position of the object into a digital surrounding-field map made available in the motor vehicle;
respective positions, ascertained relative to the motor vehicle, of foreign objects detected at least by ultrasonic measurement are stored in the digital surrounding-field map;
the surrounding-field map is updated on the basis of an odometrically determined movement of the motor vehicle;
ascertaining whether the object is moving along together with the motor vehicle, based on the distance value and positions of the object entered in the surrounding-field map; and
the existence of the occlusion is signaled only if the object is moving along together with the motor vehicle.

5. The method as recited in claim 4 , wherein for the case that the existence of the occlusion is signaled, then in the sensing range of the first ultrasonic sensor independently of the measuring signal of the first ultrasonic sensor, and on the basis of map data of the surrounding-field map, distance is measured to at least one additional foreign object which is entered in the surrounding-field map and different from the object for which the first distance value was determined.

6. The method as recited in claim 1 , wherein during operation of the motor vehicle, the occlusion is signaled acoustically only for a predetermined maximum period of time.

7. The method as recited in claim 1 , wherein, in response to the signaling of the occlusion, the first ultrasonic sensor is decoupled from a proximity warning system of the motor vehicle.

8. The method as recited in claim 1 , wherein the occlusion is signaled via a communications bus in the motor vehicle.

9. A distance-measuring apparatus for a motor vehicle, comprising:
at least one ultrasonic sensor; and
a controller including a processor configured to perform the following:
apply, by a transmitter unit, an excitation pulse to a diaphragm of the first ultrasonic sensor;
detect, by an evaluation unit, a measuring signal of the first ultrasonic sensor, and ascertain from the measuring signal a decay time of a natural oscillation of the diaphragm, brought about by the excitation pulse;
ascertain, from one of the measuring signal of the first ultrasonic sensor or a measuring signal of a second ultrasonic sensor, an echo of the excitation pulse, produced by an object located in a sensing range of the first ultrasonic sensor, and determine at least a first distance value of the object on the basis of the echo; and
signal, by the evaluation unit, an existence of the occlusion at least if (i) the decay time is less than a predetermined threshold value, and (ii) the first distance value is less than a predetermined maximum value, wherein the predetermined threshold value represents a value which is exceeded in the event at least one of ice and dirt is adhered directly to the diaphragm.

Assignees

• Volkswagen Ag

Inventors

• Mossau Daniel
• Baumann Peter
• Carsten Heinecke
• Tanner Manuel
• Sanny Knut

Classifications

• G01S2015/938

  in the bumper area · CPC title

• G01S7/52004

  Means for monitoring or calibrating (short-range imaging G01S7/5205) · CPC title

• G01S7/56

  Display arrangements {(short-range imaging G01S7/52053)} · CPC title

• G01S2015/932

  for parking operations · CPC title

• G01S15/931

  of land vehicles · CPC title