Motor Vehicle Having Occlusion Detection for Ultrasonic Sensors
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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.
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Citations
19 Claims
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1-10. -10. (canceled)
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11. A method for checking a first ultrasonic sensor of a motor vehicle for an occlusion, the method comprising:
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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. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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19. A distance-measuring apparatus for a motor vehicle, comprising:
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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.
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Specification