METHOD FOR PERFORMING A DIAGNOSIS OR SELF-TEST IN AN ULTRASOUND MEASURING SYSTEM

Description

[0001] The invention relates to a method for detecting objects in a detection space in the environment of a vehicle by means of an ultrasonic measuring system and for carrying out a self-test of an ultrasonic receiving element of the ultrasonic measuring system, wherein the ultrasonic measuring system, in addition to the ultrasonic receiving element arranged on the vehicle, has an ultrasonic transmitting element also arranged on the vehicle at a known distance from the ultrasonic receiving element.

[0002] Ultrasonic measuring systems for distance detection in the vicinity of a vehicle are used in a variety of applications. Such an ultrasonic measuring system has at least one ultrasonic transmitting element and at least one ultrasonic receiving element. Often, so-called ultrasonic transducers are used. These transducers have an oscillating element that is electrically controlled to transmit an ultrasonic measuring signal and, in the subsequent receiving phase, is mechanically stimulated to oscillate by the ultrasonic measuring signal reflected from an object. Recently, however, ultrasonic devices have been increasingly used in which a micromechanical ultrasonic transmitting element and a micromechanical ultrasonic receiving element are installed in a housing or arranged directly next to one another. Such devices are also referred to as ultrasonic transducers for the purposes of this invention.

[0003] The demands on the reliability of ultrasonic measurement systems are constantly increasing. One reason for this is that driver assistance systems based on ultrasonic measurement systems must operate reliably. Therefore, there is increasing effort to test the functionality of ultrasonic measurement systems for vehicle applications through diagnostics and / or self-tests.

[0004] Known methods for testing the functionality of ultrasonic measuring systems, particularly for automotive applications, are described in DE-B-101 64 760, JP-A-59 151076, EP-A-0 312 845, DE-A-10 2005 052 633, JP-A-2008 256521, and WO-A-2019 / 096166 (document pursuant to Art. 54(3) EPC). In these ultrasonic measuring systems, the test is carried out based on plausibility checks performed in connection with the reception of ultrasonic signals.

[0005] US-A-5 269 188 discloses an ultrasonic measuring system for non-contact material testing in which the ultrasonic sensor(s) perform self-tests.

[0006] To date, such functional checks have been performed during periods when measurements cannot be taken. Unfortunately, this means that ultrasonic measurement systems are not continuously available for measurement purposes, as is required for the detection of objects in the vicinity of a vehicle.

[0007] The object of the invention is therefore to provide a method for detecting objects in a detection space in the environment of a vehicle by means of an ultrasonic measuring system and for carrying out a self-test of the ultrasonic measuring system, in which the carrying out of a self-test of an ultrasonic receiving element and possibly also of an ultrasonic transmitting element does not come at the expense of the availability of the measuring system for the detection of potential objects in the detection space.

[0008] To achieve this object, the invention proposes a method for detecting objects in a detection space in the environment of a vehicle by means of an ultrasonic measuring system and for carrying out a self-test of an ultrasonic receiving element of the ultrasonic measuring system, wherein the ultrasonic measuring system, in addition to the ultrasonic receiving element arranged on the vehicle, has an ultrasonic transmitting element also arranged on the vehicle at a known distance from the ultrasonic receiving element, wherein in the method by means of an ultrasonic transmitting element during a measuring cycle for the purpose of detecting objects in the detection space, an ultrasonic measuring signal is emitted, within a time interval defined by the propagation speed of ultrasonic signals and the distance between the ultrasonic transmitting element and the ultrasonic receiving element, beginning with the emission of the ultrasonic measuring signal, within which time interval the measuring signal emitted by the ultrasonic transmitting element has not yet reached the ultrasonic receiving element, the ultrasonic receiving element carries out a self-test, and the self-test is completed and / or aborted at the latest at the end of the time interval.

[0009] The inventive proposal for optimizing the time available for self-tests of the ultrasonic measuring system is to perform the self-test during a measurement cycle. This is based on the realization that a certain amount of time elapses between the transmission of an ultrasonic measurement signal by an ultrasonic transmitting element and the reception of the ultrasonic measurement signal potentially reflected by an object by an ultrasonic receiving element. This applies even if the potential object is located quite close to the ultrasonic measuring system.

[0010] According to the invention, the ultrasonic receiving element is diagnosed or subjected to a self-test during the period that elapses until the ultrasonic measurement signal emitted by the ultrasonic transmitting element reaches the ultrasonic receiving element directly, so to speak. This time period is defined by the propagation speed of ultrasonic signals and the distance between the ultrasonic transmitting element and the ultrasonic receiving element to be diagnosed. In the typical application of an ultrasonic measuring system as a vehicle parking aid, the ultrasonic elements are typically located at a distance of 40 cm from one another. Due to the speed of sound, this results in a period of approximately 1.2 ms. During this time, an ultrasonic receiving element receives no signals from its neighboring ultrasonic transmitting elements, so this time can be used to perform a self-test.The self-test performed within the specified period is therefore performed without the relevant ultrasonic receiving element receiving an external ultrasonic signal, in particular the signal emitted by the ultrasonic transmitting element (possibly as a reflected signal). The invention does not exclude the possibility that the ultrasonic transmitting element may receive a control signal from the communication system to which it is electrically connected (bus connection) that triggers the self-test or transmits test signals for the self-test.

[0011] Traditionally, ultrasonic measurement systems with ultrasonic transducers are used today, particularly in the automotive sector. The ultrasonic transducers do not necessarily operate separately from one another, but are operatively connected to one another via objects potentially located in the vehicle's surroundings. The method according to the invention can be used in such a scenario in such a way that the ultrasonic measurement signal that an ultrasonic transducer initially transmits, in order to then be ready to receive the potential reflection signal, is used to specify the time period for the self-test of a neighboring ultrasonic transducer. This neighboring ultrasonic transducer would not transmit an ultrasonic measurement signal during this measurement cycle, but would wait to receive an ultrasonic reflection signal.Due to the geometric arrangement of the two ultrasonic transducers relative to the potential obstacle, it can be assumed that the ultrasonic measurement signal from the first ultrasonic transducer reflected from an object will only reach the ultrasonic transducer being diagnosed after the time period defined above has elapsed. This time period, which is determined by the speed of sound and the distance between the two ultrasonic transducers, can thus be used for self-testing purposes.

[0012] The fact that, in the scenario described above, the ultrasound transducers being diagnosed do not (or should not) emit any ultrasound measurement signals themselves does not affect the functionality of the ultrasound measurement system. In a measurement system of the type described above, an ultrasound transducer can certainly be used solely to receive reflected signals without affecting the measurement results.

[0013] With the inventive proposal, the availability of the ultrasonic measurement signal is not compromised in any way, even though the ultrasonic measurement system may be subjected to ongoing diagnostics and self-tests. Of course, such self-tests do not need to be performed continuously. However, it is nevertheless advantageous that a self-test can be performed at any time during the measurement system's functionality, i.e., at the beginning of each measurement cycle.

[0014] In a further expedient embodiment of the invention, it can be provided that the measuring system has a plurality of ultrasonic transmitting elements and a plurality of ultrasonic receiving elements and / or a plurality of combinations designed as ultrasonic transducers, each comprising an ultrasonic transmitting element and an ultrasonic receiving element, and that in a measuring cycle at least one ultrasonic transmitting element transmits an ultrasonic measuring signal and a self-test is carried out for a plurality of ultrasonic receiving elements, specifically within time intervals which each begin with the transmission of the ultrasonic measuring signal and end after times defined by the propagation speed of ultrasonic signals and the distances between the ultrasonic transmitting element and the respective ultrasonic receiving elements.

[0015] The method according to the invention can be used especially in measuring systems that have several ultrasonic elements, some of which are designed as ultrasonic transmitting elements and the others as ultrasonic receiving elements.

[0016] As already described above, the ultrasonic elements of the typically used ultrasonic measuring systems can be designed as microelectroacoustic mechanical elements (MEAMF).

[0017] As already mentioned above, the ultrasonic measuring system has several ultrasonic transducers, each designed as a combination of an ultrasonic transmitter and an ultrasonic receiver.

[0018] In addition to the possibility already described above of considering as ultrasonic transducers within the scope of the invention also devices in which two mechanical microelectroacoustic elements are installed, one of which functions as a transmitting element and the other as a receiving element, a common electroacoustic oscillating element is used in an ultrasonic transducer of conventional design, which both transmits the ultrasonic measurement signal and receives ultrasonic signals and in particular ultrasonic reflection signals.

[0019] As already mentioned above, it is advisable to operate an ultrasound transducer exclusively as an ultrasound receiver if the transducer is to be diagnosed or subjected to a self-test.

[0020] In a further expedient embodiment of the invention, it can be provided that the measuring system has a control unit and that the ultrasonic transmitting elements and ultrasonic receiving elements are controlled to initiate a measuring cycle with or without a self-test.

[0021] Finally, in an expedient embodiment of the invention, it can also be provided that signals and / or data required during a self-test are evaluated to analyze the state and / or functionality of the ultrasonic receiving element and / or the ultrasonic transmitting element of an ultrasonic transducer designed as a combination of an ultrasonic transmitting element and an ultrasonic receiving element.

[0022] The key advantage of the inventive approach is the optimization of the availability of an ultrasonic measuring system for measurement purposes. Unlike conventional systems, no time periods outside of the measurement period need to be made available for performing the self-test. This allows the active measurement time to be extended, allowing measurements to be performed without interruptions, thus making more measurement data available for the ultrasonic system. This, in turn, is important for the application of the invention in the automotive sector for driver assistance systems. With the invention, previously unused time can now be used to perform measurements without having to forego self-tests.

[0023] The self-tests can be performed according to a wide variety of scenarios based on signals generated internally or externally via a bus connection of the ultrasonic receiving element. For an example of a self-test of an ultrasonic receiving element, see WO-A-2019 / 030113.

[0024] The invention is explained in more detail below with reference to the drawing. The drawing shows a schematic plan view of the rear of a vehicle, in whose bumper four ultrasonic elements in the form of ultrasonic transducers are arranged. These elements interact with a control unit, for example, via a bus system (or in a point-to-point configuration).

[0025] For example, four ultrasonic transducers 12, 14, 16, and 18 are installed in the rear of the vehicle 10, whose ultrasonic signals are transmitted into a detection area 20. The ultrasonic measuring system 22 also has a (central) control unit 24 that controls the ultrasonic elements 12, 14, 16, and 18 and receives their possibly preprocessed received signals. The control unit 24 can further process these received signals itself or, if necessary, forward these signals after intermediate processing to a higher-level control unit (not shown). All of this is of secondary importance to the invention.

[0026] As already described above, the four ultrasonic elements are designed as ultrasonic transducers. The distance 26 between adjacent ultrasonic transducers is known. In this exemplary embodiment, it is assumed that the four ultrasonic transducers are arranged adjacent to each other at a distance of 40 cm. The propagation time for an ultrasonic measurement signal, emitted, for example, by ultrasonic transducer 12, is therefore 1.2 ms until this ultrasonic measurement signal directly reaches the adjacent transducer 14. The signal path can be provided via the air or via the material of the bumper.

[0027] In one possible scenario for implementing the method according to the invention, for example, the two ultrasonic transducers 14 and 18 operate in transmit / receive mode, while the other two ultrasonic transducers 12, 16 are operated exclusively in receive mode. In this configuration, as illustrated by way of example in the drawing, two different objects 28, 30 can be detected. The object 28 reflects the ultrasonic measurement signal emitted by the ultrasonic transducer 18 both back to the ultrasonic transducer 18 and toward the adjacent ultrasonic transducer 16, which operates in receive mode. Likewise, the ultrasonic measurement signal emitted by the ultrasonic transducer 14 is reflected by the object 30 on the one hand back to the ultrasonic transducer 14, but also reaches the adjacent ultrasonic transducers 12 and 16 on the other.The time period within which the ultrasonic transducers 14, 16 operating in receive mode can perform a self-test begins when the ultrasonic transducers 14, 18 begin transmitting the ultrasonic measurement signals. In this exemplary embodiment, the time period ends after approximately 1.2 ms. Typically, this time is sufficient to perform at least some of the self-test steps required to maintain the functionality of the system. If the entire self-test cannot be performed within the specified time period, the self-test can be performed step by step over several such periods.

[0028] The previously described different operation of the four ultrasonic transducers 12, 14, 16, 18 can be carried out alternately or cyclically, swapped or continuously, so that all ultrasonic transducers can be examined one after the other for their functionality.

[0029] The previous section discussed performing the self-test. However, in addition to the self-test, a diagnosis can also be performed. LIST OF REFERENCE SYMBOLS

[0030] 10 Vehicle 12 Ultrasonic transducer (ultrasonic element) 14 Ultrasonic transducer (ultrasonic element) 16 Ultrasonic transducer (ultrasonic element) 18 Ultrasonic transducer (ultrasonic element) 20 Detection space 22 Ultrasonic measuring system 24 Control unit 26 Distance between two ultrasonic transducers 28 Object 30 Object

Claims

1. Method for detecting objects in a detection range in the environment of a vehicle using an ultrasound measuring system (22) and for performing a self-test of an ultrasound receiving element of the ultrasound measuring system, the ultrasound measuring system comprising, in addition to the ultrasound receiving system arranged on the vehicle, an ultrasound transmitting element also arranged on the vehicle at a known distance from the ultrasound receiving element, wherein in the method - an ultrasound measuring signal is emitted by means of an ultrasound transmitting element (12, 14, 16, 18) during a measuring cycle so as to detect objects (28, 30) in the detection range (20), - the ultrasound receiving element (12, 14, 16, 18) performs a self-test within a time interval within which the measuring signal emitted by the ultrasound transmitting element (12, 14, 16, 18) has not yet reached the ultrasound receiving element (12, 14, 16, 18), said interval being defined by the propagation speed of ultrasound signals and the distance (26) between the ultrasound transmitting element (12, 14, 16, 18) and the ultrasound receiving element (12, 14, 16, 18) and starting with the emission of the ultrasound measuring signal, and - the self-test is terminated or aborted at the end of the time interval at the latest.

2. Method according to claim 1, wherein the measuring system comprises a plurality of ultrasound transmitting elements (12, 14, 16, 18) and a plurality of ultrasound receiving elements (12, 14, 16, 18) and / or a plurality of ultrasound receiving elements (12, 14, 16, 18) and / or a plurality of combinations each of one ultrasound transmitting element (12, 14, 16, 18) and one ultrasound receiving element (12, 14, 16, 18), configured as ultrasound transducers (12, 14, 16, 18), and wherein, in a measuring cycle, at least one ultrasound transmitting element (12, 14, 16, 18) emits an ultrasound measuring signal and a self-test is performed for each of a plurality of ultrasound receiving elements (12, 14, 16, 18), namely within time intervals each starting with the emission of the ultrasound measuring signal and ending after periods defined by the propagation speed of ultrasound signals and the distances (26) between the ultrasound transmitting element (12, 14, 16, 18) and the respective ultrasound receiving elements (12, 14, 16, 18) and within which the measuring signal emitted by the ultrasound transmitting element (12, 13, 16, 18) has not yet reached the respective ultrasound receiving element (12, 14, 16, 18).

3. Method according to claim 1 or 2, wherein the ultrasound measuring system (22) comprises a plurality of ultrasound elements of which some are configured as ultrasound transmitting elements (12, 14, 16, 18) and others are configured as ultrasound receiving elements (12, 14, 16. 18).

4. Method according to claim 3, wherein the ultrasound elements are configured as micro-electro-acoustic mechanical elements (MEAMF).

5. Method according to one of claims 1 or 2, wherein the ultrasound measuring system (22) comprises a plurality of ultrasound transducers (12, 14, 16, 18), each configured as a combination of an ultrasound transmitter and an ultrasound receiver.

6. Method according to claim 5, wherein, in an ultrasound transducer (12, 14, 16, 18), a common electro-acoustic oscillating element both emits the ultrasound measuring signal and receives ultrasound signals and in particular ultrasound reflection signals.

7. Method according to any one of claims 2 to 6, wherein an ultrasound transducer (12, 14, 16, 18) is operated as an ultrasound transmitter for self-test purposes.

8. Method according to any one of claims 1 to 7, wherein the measuring system comprises a control unit (24), and wherein the ultrasound transmitting elements (12, 14, 16, 18) and the ultrasound receiving elements (12, 14, 16, 18) are controlled by the control unit (24) to initiate a measuring cycle with or without a self-test.

9. Method according to any one of claims 1 to 8, wherein, in a self-test, required signals and / or produced data are evaluated for an analysis of the state and / or the functionality of an ultrasound receiving element (12, 14, 16, 18) and / or an ultrasound transmitting element (12, 14, 16, 18) or the ultrasound receiving element (12, 14, 16, 18) and / or the ultrasound transmitting element (12, 14, 16, 18) of an ultrasound transducer (12, 14, 16, 18) configured as a combination of an ultrasound receiving element (12, 14, 16, 18) and an ultrasound transmitting element (12, 14, 16, 18).