Method for operating an ultrasonic sensor

Abstract

To provide a method for operating an ultrasonic sensor.SOLUTION: A method for operating an ultrasonic sensor is proposed, in which a diagnosis is carried out in an operating cycle after the end of a measurement, in which diagnosis an oscillation element of the ultrasonic sensor is weakly excited while maintaining all configuration settings of the ultrasonic sensor. This procedure is preferably carried out after each measurement, so that a failure or an indication of a failure of the ultrasonic sensor can be ascertained in good time for each measurement.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for operating an ultrasonic sensor, which comprises an electrically drivable vibration element and an electronic circuit arrangement having a drive circuit for driving the vibration element and a signal processing circuit for processing an electrical measurement signal supplied by the vibration element, the ultrasonic sensor being in particular part of a measurement and communication bus system having a bus wiring to which at least one ultrasonic sensor and a control unit for outputting control data to the at least one ultrasonic sensor and receiving result data from the at least one ultrasonic sensor are connected. [Background technology]

[0002] Ultrasonic sensors are used in the automotive sector to assist in automated driving, for example for parking assistance systems. For safety reasons, it is important that the functional availability of such ultrasonic sensors is always ensured.

[0003] In the prior art, in this regard, diagnostic procedures are performed from time to time between individual operating cycles to check the excitation path that drives the transducer elements to generate ultrasound waves and the receive path for the echo-based electrical signals.

[0004] US Pat. No. 5,699,499 describes an improved UART data transmission for transmitting echo data to a higher-level computer system in real time.

[0005] US Pat. No. 5,649,999 describes a sensor device comprising a sensor for monitoring the environment using acoustic waves.

[0006] The diagnostics performed to date are suboptimal for a variety of reasons. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] German Patent Application Publication No. 102022120106B3 [Patent Document 2] German Patent Application Publication No. 102017203136A1 Summary of the Invention [Problem to be solved by the invention]

[0008] The object of the present invention is to improve the reliability of operation of ultrasonic sensors by optimizing the diagnostic phase. [Means for solving the problem]

[0009] In order to achieve this object, the present invention relates to a method for operating an ultrasonic sensor, which comprises an electrically drivable vibration element (also called an electro-acoustic transducer, or transducer, in this case also called an ultrasonic transducer) and an electronic circuit arrangement having a drive circuit for driving the vibration element and a signal processing circuit for processing an electrical measurement signal supplied by the vibration element, the ultrasonic sensor being in particular part of a measurement and communication bus system having a bus wiring to which at least one ultrasonic sensor and a control unit for outputting control data to the at least one ultrasonic sensor and for receiving result data from the at least one ultrasonic sensor are connected, the method comprising: operating at least one ultrasonic sensor using one of a plurality of possible configuration parameter sets for execution of a number of successive operating cycles; In this case, each operation cycle is an excitation step in which a vibrating element of the at least one ultrasonic sensor is excited to transmit an ultrasonic signal by an excitation drive signal having a predefined signal shape and a predefined amplitude determined by a currently used set of configuration parameters; a decay phase following the excitation phase, in which the vibration element decays; a receiving step following the attenuation step, in which the vibrating elements are excited by potential ultrasonic echo signals and electrical measurement signals generated thereby by the vibrating elements are processed by a signal processing circuit; a data transmission step of transmitting result data representing a result of the signal processing from the at least one ultrasonic sensor to the control unit via a bus line; a pause phase between the end of the receiving phase and the start of the data transmitting phase, performing, within the resting phase for a specifiable number of successive operating cycles, a diagnostic phase for checking the functional reliability of at least one ultrasonic sensor; The vibration elements of at least one ultrasonic sensor are excited by a diagnostic drive signal having the same signal shape as the excitation drive signal, the diagnostic drive signal being used to excite the vibration elements during an excitation phase of an operating cycle and having an amplitude several orders of magnitude smaller than the excitation drive signal.

[0010] In the following, the invention will be explained on the basis of the ultrasonic sensor being configured as an ultrasonic transceiver.

[0011] An ultrasound transceiver of the present invention is conventionally operated according to a number of time-sequential operating cycles. Typically, the operating cycles, which relate to driving electroacoustic vibration signals and processing received signals, are defined by configuration parameters that determine, among other things, the shape and magnitude of the excitation drive signal and the operating parameters of circuit components (e.g., filters).

[0012] According to the present invention, during at least one of the operating cycles, a diagnostic phase is performed following the receiving phase. In this diagnostic phase, the transducer elements are excited using the same configuration parameters as used in the operating cycle, but with a significantly reduced amplitude compared to the excitation drive signal used in the excitation phase of the operating cycle. This weak excitation of the transducer elements causes them to generate weak ultrasound waves, which do not generate echo signals or interfere with the diagnosis. As a result, the diagnostic drive signal passes through the receiving path, and processing of the diagnostic drive signal makes it possible to detect whether the transducer elements are operating normally and whether the receiving path is functioning properly.

[0013] A feature of the present invention is that for diagnostic purposes, an ultrasonic transceiver is excited with a very low electrical output, causing its vibration elements to vibrate with a relatively small amplitude, and then the start and stop of the vibration of the vibration elements and the signal applied to the ultrasonic transceiver at that time are evaluated. This is done in the same configuration as when the ultrasonic transceiver was operating in the previous actual measurement phase. The signal applied to the ultrasonic transceiver in the actual excitation phase to detect echoes is not suitable for diagnostic purposes because its magnitude is too large and it over-controls the receive path. In addition, this signal may already be interfered with by nearby echoes. The very weak excitation in the diagnostic phase allows the vibration of the vibration elements to be kept within a measurable range, and in some cases the echo generated is small and negligible.

[0014] According to the present invention, the ultrasonic transceiver is checked for correct operation periodically or irregularly, particularly at each measurement. In this case, the ultrasonic transceiver excitation, the transducer itself, the signal path, and the configuration parameters selected by the current configuration profile are checked thoroughly and in accordance with the application. Transient faults affecting the measurement can also be detected because the diagnosis is performed in close time proximity to the relevant measurement, particularly each measurement. Sporadic faults from other circuits required for configuration (e.g., EEPROM and register failures) are detected by diagnostic signals. On the other hand, reconfiguring the entire system for diagnosis (as in the prior art) does not reveal faulty configurations in previous measurements.

[0015] Previously, diagnostics of ultrasound transceivers were performed as separate measurements, which required additional time and led to interruptions of the measurement sequence. This is because, according to the conventional concept, the measurement cycle, i.e., the continuous operating cycle, had to be interrupted to load the diagnostic configuration parameters, perform the diagnosis, restore the configuration for the next measurement, and restart the measurement cycle. Diagnostic configuration requires additional program memory, such as RAM or flash memory. Prior art also employed a method of using a path for diagnostics that was different from the application (measurement) by switching between the transmit and receive paths. Previously, diagnostics used selected configuration data sets for excitation, amplification, filter settings, filter coefficients, and reception, which did not necessarily match the settings used in the original application. With the new concept, the diagnostic phase is automatically performed using the same configuration profile (with the only exception being that the excitation signal amplitude is significantly reduced), making diagnostics time-efficient and user-friendly. No configuration parameter changes are required.

[0016] The configuration profile includes, for example, the number, shape and frequency of pulses of the burst excitation signal normally used to drive the vibrating element, the excitation current or voltage, i.e., excitation power, amplification, measurement time, diagnostic parameters, coding, chirp-up and chirp-down settings, etc. The profiles can be created for near-field, far-field and differently coded signals and can be flexibly selected by the measurement command. Diagnostic signals that "fit" this measurement command always use the respective active configuration profile.

[0017] The method according to the present invention is applicable to both transformer and transformerless ultrasonic transceivers, including transformerless systems with fully integrated transducer connections.

[0018] Finally, it should be noted that the insertion of a diagnostic phase into the operating cycle does not cause a delay in the data and results transferred after the actual measurement. The diagnostic utilizes a time separation (pause phase) that is necessary for other reasons. Such a pause is necessary to achieve a clear separation between the echo output and the result transmission / data communication on the data line to which the ultrasound transducer is normally connected to the command unit. The result of the diagnostic is advantageously compressed into a "normal / abnormal" bit, which is transmitted together (integrated) with the other diagnostic results after the measurement phase has ended. The transmission of additional diagnostic information does not require additional data communication.

[0019] In an advantageous embodiment of the present invention, as described above, each configuration parameter set includes specifications of operating parameters for the shape of the excitation drive signal, the magnitude of its amplitude, the magnitude of the amplitude of the diagnostic drive signal, and for the excitation drive signal and the diagnostic drive signal in the excitation path, and for the measurement and function reliability check signals of the signal processing circuitry supplied by at least one ultrasonic sensor in the receive path.

[0020] As already briefly mentioned above, at least one ultrasound transceiver may have a transformer for converting the excitation drive signal and the diagnostic drive signal, or at least one ultrasound transceiver may not have a transformer.

[0021] Preferably, the amplitude of the diagnostic drive signal is less than the amplitude of the excitation drive signal of the operating cycle by at least 10 orders of magnitude. 6 ~10 3 Especially during the 10 5 ~10 3 Especially during the 10 4 ~10 3 Between 5 x 10 and 5 x 10 5 ~6×10 3 It is between.

[0022] Preferably, after a fixed or varying number of operating cycles, the at least one ultrasound transceiver may be operated through an operating cycle with a diagnosis of the functional reliability of the at least one ultrasound transceiver.

[0023] However, advantageously, a diagnostic of the functional reliability of at least one ultrasound transceiver is performed during each operating cycle.

[0024] Instead of an ultrasonic transceiver, the ultrasonic sensor is formed from two parts, an ultrasonic transmitter, each having a vibration element, and an ultrasonic receiver, and in a diagnostic phase, the vibration elements of the ultrasonic receiver and / or the vibration elements of the ultrasonic transmitter are excited, thereby checking the functional reliability of the receiving path of the ultrasonic receiver and / or the excitation path of the ultrasonic transmitter.

[0025] The invention will be explained in more detail below on the basis of examples and with reference to the drawings. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a diagram showing an example of a typical topology of an ultrasonic measurement system including a command unit and a plurality of ultrasonic sensors; [Figure 2] FIG. 1 is a block diagram of the main components of an ultrasonic sensor drive, with a clarification of the signal flow (excitation path and reception path) and the drive of different components depending on the configuration parameter set or profile selected for the operating cycle. [Figure 3] 1 is a diagram for clearly illustrating the signal course in an ultrasonic sensor during the excitation phase as well as the actual measurement phase and during the diagnostic phase; DETAILED DESCRIPTION OF THE INVENTION

[0027] 1 shows an exemplary configuration of an ultrasonic measurement system 10 comprising a number of ultrasonic sensors 12 and a control unit 14 (command unit), all connected to one another via a communication bus 16. Alternatively, the communication can take the form of a point-to-point connection.

[0028] The parts of the drive unit 18 of each ultrasonic sensor 12 that are important to the present invention are shown in FIG. 2. The drive unit 18 has a Supply terminal 20 and a GND terminal 22 for power supply, as well as an I / O interface 24 for communication. The drive unit 18 has a generator 26 for generating an excitation drive signal for the ultrasonic sensor 12, which in this embodiment is configured as a burst generator. The generator 26 drives a driver 28, which excites (with or without a transformer) a vibration element 30 (US transducer) of the ultrasonic sensor 12, typically arranged outside the drive unit 18, to generate ultrasonic waves intended for measurement. The generator 26 and the driver 28 belong to an excitation path 32 of the drive unit 18.

[0029] The drive unit 18 further comprises a receiving path 34, via which it processes the electrical signals present at the vibration elements 30 or the ultrasonic sensors 12 and transmits them to the interface 24. The receiving path 34 contains, inter alia, an analog signal processing unit 36, which converts the electrical signals generated by the vibration elements 30, possibly after amplification, into digital signals. The analog signal processing unit 36 ​​is connected to a digital signal processing unit 38, which converts the analog signals into digital signals on its behalf. The signals processed by the digital signal processing unit 38 are sent via a communication interface 40 to the data interface 24, from which the processed signals, i.e., for example result signals representative of the measurement results or raw data representative of the measurement results, are transmitted to the control unit 14.

[0030] The circuit components, i.e., generator, driver, analog signal processing unit, and digital signal processing unit, are typically configurable according to one of several configuration profiles and can be operated with corresponding configuration parameters. The communication interface 40 is also configurable. Configuration is performed by a control unit 43, which also performs other control functions in the drive unit 18 of the ultrasonic sensor 12. Configurable settings include, among others, the signal waveform / frequency form for excitation, i.e., for example, the number, frequency, and shape of pulses generated by the generator 26, the magnitude of the drive signal reaching the vibration element 30, and settings for both the signal processing unit and the communication interface.

[0031] Each ultrasonic sensor operates continuously according to a succession of operating cycles. As is typical for ultrasonic sensors, the initial operating cycle includes an excitation phase 42 in which the generator 26 generates a burst signal, which the driver 28 amplifies and supplies to the vibrating element 30 of the ultrasonic sensor 12, as shown in FIG. 3. The vibrating element 30 then begins to vibrate, and this vibration continues for a period of time after the excitation phase 42 ends (see vibration signal 45 during excitation phase 42 and vibration signal 45 during decay phase 44 in FIG. 3).

[0032] The damping phase 44 is followed by the actual measurement phase in the form of a reception phase 46. At the end of the reception phase 46, a measurement result for detecting an obstacle is obtained (e.g., in the form of data indicating the presence of an obstacle at a certain distance from the vehicle). This evaluation or decision is then made on the basis of the measurement results of a number of ultrasonic sensors in the control unit 14.

[0033] The receiving stage 46 is usually followed by a pause stage 48, which is necessary to ensure a clear separation between the echo output (end of the echo signal) and the resulting transmission / data communication.

[0034] According to the present invention, this pause phase 48 is used for a diagnostic (see diagnostic phase 50 in FIG. 3 ) to check the functional reliability of the ultrasonic sensor 12. To this end, the vibration elements 30 of the ultrasonic sensor 12 are driven by a diagnostic drive signal 52, which has the same signal shape and frequency as the excitation drive signal 41. However, the amplitude of this diagnostic drive signal 52 is several orders of magnitude smaller than that of the excitation drive signal 41. Due to the small diagnostic drive signal 52, the vibration elements 30 vibrate weakly (see 54 in FIG. 3 ). This weak vibration of the vibration elements 30 is sufficient to check the correct functioning of the receive path 34. Similarly, the excitation path 32 can also be checked in this manner. The test (diagnosis) results are transmitted via the communication interface 40. In this case, together with the ultrasonic measurement results, a data stream representing the results may contain, for example, a single bit indicating whether functional reliability is ensured or multiple bits for encoding and transmitting the potential fault type.

[0035] 3 shows a typical example of the envelope of the received signal at the receive stage 46. At the diagnostic stage 50, a signal 51 is processed and recognized as being transmitted via the receive path 34.

[0036] In the diagnostic phase 50 according to the invention, the ultrasonic sensor 12 operates in the same configuration as in the excitation, damping and receiving phases, with the (only) difference being that the diagnostic drive signal 52 is significantly smaller than the excitation drive signal 41. This results in a vibration signal 54 in the diagnostic phase 50 that is significantly smaller than the vibration signal 45 in the previous excitation phase 42 and damping phase 44. In the simplest case, in the diagnostic phase 50 the signal 51 present in the vibrating element 30 is compared with a threshold value. If the signal 51 exceeds this (diagnostic) threshold value, the ultrasonic sensor is operating normally, otherwise it is not operating normally.

[0037] The ultrasonic sensor described above has been described based on the example of an ultrasonic transceiver having an ultrasonic transducer, i.e., an ultrasonic transducer, that alternately operates to transmit ultrasonic waves and, for example, receive ultrasonic echoes. However, the present invention is also applicable to ultrasonic measurement systems that use an ultrasonic transmitter to transmit ultrasonic waves and an ultrasonic receiver separate from the ultrasonic transmitter to receive echo signals. According to the present invention, the ultrasonic receiver includes a generator that generates a diagnostic drive signal, and during the diagnostic phase, it operates with the same configuration parameters or the same configuration profile as used in the above-described operating cycle in which the diagnostic phase is performed. The ultrasonic transmitter, as in the ultrasonic sensor, is also driven in parallel for diagnostic purposes. Weak signals present in the vibrating elements of the ultrasonic transmitter are also analyzed, thereby analyzing / diagnosing the functional viability of the ultrasonic transmitter. [Explanation of symbols]

[0038] 10 Ultrasonic Measurement System 12 Ultrasonic Sensor 14 Control unit (command unit) 16 Communication Bus 18 Drive unit 20 Supply terminal 22 GND terminal 24 I / O interfaces 26 Generator 28 Drivers 30 vibration elements 32 Excitation Pathway 34 Receiving Path 36 Analog Signal Processing Unit 38 Digital Signal Processing Unit 40 Communication Interface 41 Excitation drive signal 42 Excitation Stage 43 Control Unit 44 Decay Stages 45 Vibration signal during the excitation stage 46 Reception stage 48 Rest Phase 50 Diagnostic Stage 51 Vibration signals in the diagnostic stage 52 Diagnostic drive signal 54 Vibration in the diagnostic stage

Claims

1. 1. A method for operating an ultrasonic sensor comprising an electrically activatable vibration element and an electronic circuit arrangement having a drive circuit for driving the vibration element and a signal processing circuit for processing an electrical measurement signal provided by the vibration element, the ultrasonic sensor being part of a measurement and communication bus system having bus wiring to which at least one ultrasonic sensor and a control unit for outputting control data to the at least one ultrasonic sensor and for receiving result data from the at least one ultrasonic sensor are connected, operating the at least one ultrasonic sensor using one of a plurality of possible configuration parameter sets for execution of a number of successive operating cycles; In this case, each operation cycle is an excitation step in which the vibration elements of the at least one ultrasonic sensor are excited to transmit ultrasonic signals by excitation drive signals having a predefined signal shape and a predefined amplitude determined by a currently used set of configuration parameters; a decay stage following the excitation stage, in which the vibration element decays; a receiving step following the attenuation step, in which the transducer elements are excited by potential ultrasonic echo signals, and the electrical measurement signals generated thereby by the transducer elements are processed by the signal processing circuitry; a data transmission step of transmitting result data representing a result of signal processing from the at least one ultrasonic sensor to the control unit via the bus wiring; a pause step between the end of the receiving step and the start of the data transmitting step; performing, within said resting phase for a specifiable number of successive operating cycles, a diagnostic phase for checking the functional reliability of said at least one ultrasonic sensor; and exciting the vibration elements of the at least one ultrasonic sensor with a diagnostic drive signal having the same signal shape as the excitation drive signal, the diagnostic drive signal being used to excite the vibration elements during the excitation phase of the operating cycle and having an amplitude several orders of magnitude smaller than the excitation drive signal.

2. 2. The method of claim 1, wherein each configuration parameter set includes specifications of operating parameters for the shape of the excitation drive signal, the magnitude of its amplitude, the magnitude of the amplitude of the diagnostic drive signal, and for the excitation drive signal and the diagnostic drive signal in the excitation path, and for the measurement and function reliability check signals of the signal processing circuit provided by the at least one ultrasonic sensor in the receive path.

3. the at least one ultrasonic sensor comprises a transformer for transforming the excitation drive signal and the diagnostic drive signal; or 3. The method according to claim 1, wherein the at least one ultrasonic sensor does not have the transformer.

4. The number of orders of magnitude that the amplitude of the diagnostic drive signal is smaller than the amplitude of the excitation drive signal for the operating cycle is 10 ６ ~10 ３ During the period, especially 10 ５ ~10 ３ During the period, especially 10 ４ ~10 ３ and preferably between 5×10 ５ ~6 x 10 ３ The method according to any one of claims 1 to 3, characterized in that:

5. 5. The method according to claim 1, wherein the at least one ultrasonic sensor is operated by an operating cycle with a diagnosis of the functional reliability of the at least one ultrasonic sensor after a fixed or variable number of operating cycles.

6. 6. The method according to claim 5, characterized in that a diagnostic of the functional reliability of said at least one ultrasonic sensor is carried out at each operating cycle.

7. The method according to any one of claims 1 to 6, characterized in that the ultrasonic sensor, as an ultrasonic transceiver, has a single vibration element for transmitting ultrasonic waves and receiving ultrasonic echo waves.

8. 7. The method according to claim 1, wherein the ultrasonic sensor is formed from two parts, each of which has an ultrasonic transmitter and an ultrasonic receiver, each of which has a vibration element, and wherein in the diagnostic stage, the vibration elements of the ultrasonic receiver and / or the vibration elements of the ultrasonic transmitter are excited, thereby checking the functional reliability of the receiving path of the ultrasonic receiver and / or the excitation path of the ultrasonic transmitter.

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