LU92933B1 - Adaptive signal threshold for triggering kick detection - Google Patents

Adaptive signal threshold for triggering kick detection Download PDF

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Publication number
LU92933B1
LU92933B1 LU92933A LU92933A LU92933B1 LU 92933 B1 LU92933 B1 LU 92933B1 LU 92933 A LU92933 A LU 92933A LU 92933 A LU92933 A LU 92933A LU 92933 B1 LU92933 B1 LU 92933B1
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LU
Luxembourg
Prior art keywords
threshold
sensor
value
sensor signal
signal
Prior art date
Application number
LU92933A
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German (de)
Inventor
Baptiste Anti
Johann Bar
Hans Peter Beise
Thomas Stifter
Original Assignee
Iee Sa
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Publication date
Application filed by Iee Sa filed Critical Iee Sa
Priority to LU92933A priority Critical patent/LU92933B1/en
Priority to PCT/EP2016/069639 priority patent/WO2017032693A1/en
Priority to US15/753,794 priority patent/US10432194B2/en
Priority to DE112016003831.3T priority patent/DE112016003831T5/en
Priority to CN201680048867.1A priority patent/CN107925405B/en
Application granted granted Critical
Publication of LU92933B1 publication Critical patent/LU92933B1/en

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Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/94—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the way in which the control signals are generated
    • H03K17/945—Proximity switches
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K2217/00—Indexing scheme related to electronic switching or gating, i.e. not by contact-making or -breaking covered by H03K17/00
    • H03K2217/94—Indexing scheme related to electronic switching or gating, i.e. not by contact-making or -breaking covered by H03K17/00 characterised by the way in which the control signal is generated
    • H03K2217/9401—Calibration techniques
    • H03K2217/94026—Automatic threshold calibration; e.g. threshold automatically adapts to ambient conditions or follows variation of input
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K2217/00—Indexing scheme related to electronic switching or gating, i.e. not by contact-making or -breaking covered by H03K17/00
    • H03K2217/94—Indexing scheme related to electronic switching or gating, i.e. not by contact-making or -breaking covered by H03K17/00 characterised by the way in which the control signal is generated
    • H03K2217/9401—Calibration techniques
    • H03K2217/94031—Calibration involving digital processing

Abstract

A method of operating a sensor system, the sensor system comprising at least one sensor (26, 30), in particular designed as a proximity sensor (26, 30), with regard to generating a trigger signal (40) indicative of an occurrence of an event, in particular an operator-intended event in the presence of noise, the method comprising repetitive steps of acquiring (50) the sensor signal (28, 32) at specified sampling times, comparing (52) a value obtained as a presently sampled sensor signal (28, 32) with a presently valid first threshold value (36), generating (54) a trigger signal (40) if the value obtained as the presently sampled sensor signal (28, 32) is as large as or exceeds the presently valid first threshold value (36), omitting to generate a trigger signal (40) if the value obtained as the presently sampled sensor signal (28, 32) is less than or equal to the presently valid first threshold value (36), forming (56) a subset (44) out of the sampled sensor signals (28, 32), wherein a predetermined number of subsequently acquired sensor signals (28, 32) preceding the presently sampled sensor signal (28, 32) is excluded from forming the subset (44), based on the formed subset (44) of sampled sensor signals (28, 32), determining (58) an update value for the first threshold value (36), and replacing (60) the presently valid first threshold value (36) by the update value for the first threshold value (36) as a new presently valid first threshold value (36). (Figure 1) 92933

Description

Adaptive Signal Threshold for Triggering Kick Detection
Technical field [0001] The invention relates to method of operating a sensor system with regard to generating a trigger signal indicative of an occurrence of an event in the presence of noise, a control unit for a system for generating a trigger signal for the activation of a motor-driven vehicle door member using such method, and a software module for carrying out the method.
Background Art [0002] Sensor-controlled automatic actuation of motorized tailgates of motor vehicles is known in the art.
[0003] Utility model document DE 20 2005 020 140 U1 describes a motor vehicle door arrangement with at least one motor vehicle door and a drive for motorized movement of the motor vehicle door from the closed position into the open position and from the open position into the closed position. The arrangement further comprises a control for triggering the drive, the control being assigned an optionally actuatable mobile part which the user generally carries and which interacts with the control means over a wireless transmission link when the user approaches the motor vehicle, enhanced activation automatically carrying out opening and/or a closing as triggered by a predetermined process of use and without the necessity of activating the mobile part. In one embodiment, provision is made for a user-side operator control event, namely a user-side foot movement, to cause the motorized opening of the tailgate. With respect to enhanced activation, the control means, especially with the vehicle stopped, can be moved into the activated and deactivated states, and can be triggered by the predetermined usage process exclusively when the control means is in the activated state.
[0004] Further, international application WO 2012/084111 A1 describes a closure element assembly of a motor vehicle having a motor-displaceable closure element, wherein a sensor assembly and a sensor controller are provided for generating an operating message. By means of the operating message, motor displacement of the closure element can be triggered. The sensor controller monitors the sensor-measured values during operating event monitoring. During fault situation monitoring, the sensor controller monitors the sensor-measured values for the occurrence of a behavior that is characteristic of a fault situation.
[0005] During the fault situation monitoring process, the sensor controller increments a "fault indicator·' variable if an indication of a fault is registered at the monitoring time and, when a predetermined threshold value for the fault indicator is exceeded, a fault situation is registered as true in the sensor controller. The sensor controller generates an operating message only when, according to the two monitoring actions, an operating event but no fault situation is present.
[0006] An operational reliability of the above-presented prior art application crucially depends on an ability of the employed method for detecting an occurrence of an operator-intended event in surroundings comprising noise, for instance from interfering objects, whose magnitude may suffice to reach any predetermined threshold value set for triggering.
[0007] In the above-described systems of the prior art, when a foot or leg approaches a sensor, a sensor-generated signal is increasing. When a specified threshold is crossed, the system performs advanced measurements to validate/invalidate the foot movement.
[0008] Defining a low fixed specified threshold value, in order to start advanced measurements as soon as possible to react quickly to an event, is not viable if the signal noise is too high. The specified threshold would be crossed too often, and this would result in excessive power consumption.
[0009] Conversely, defining a high fixed specified threshold value in order to be protected against noise could result in a poor system performance, as the reaction to the event would occur in a delayed way.
Object of the invention [0010] It is therefore desirable to have a method of operating a sensor system with regard to generating a trigger signal indicative of an occurrence of an operator-intended event with an improved performance regarding detection of operator-intended events in the presence of noise, sensor system power consumption and fast response to operator-intended events.
Summary of the Invention [0011] In one aspect of the present invention, the object is achieved by a method of operating a sensor system, wherein the sensor system comprises at least one sensor that generates a sensor signal indicative of a sensed physical quantity, with regard to generating a trigger signal indicative of an occurrence of an event in the presence of noise. The method comprises repetitive steps of acquiring the sensor signal at specified sampling times, comparing a value obtained as a presently sampled sensor signal with a presently valid first threshold value, generating a trigger signal if the value obtained as the presently sampled sensor signal is as large as or exceeds the presently valid first threshold value, omitting to generate a trigger signal if the value obtained as the presently sampled sensor signal is less than the presently valid first threshold value, forming a subset out of the sampled sensor signals, wherein a predetermined number of subsequently acquired sensor signals preceding the presently sampled sensor signal is excluded from forming the subset, based on the formed subset of sampled sensor signals, determining an update value for the first threshold value, replacing the presently valid first threshold value by the update value for the first threshold value as a new presently valid first threshold value.
[0012] One advantage of the method lies in that false trigger due to time dependent noise are reliably prevented as the updated threshold value prevents generating a trigger signal in the presence of time-dependent noise. It will be noted that the method is an adaptive method, which means that that the first threshold value may be increased in an high noise environment or may be lowered in a low noise environement. The method thus adapts the sensitivity to the corresponding environment and thus ensures reliable detection of a trigger event.
[0013] The noise may be caused by changes in the surroundings with regard to the physical quantity to which the at least one sensor is sensitive. The noise may also have its origin in electromagnetic interference (EMI).
[0014] Another advantage lies in that at the same time, a trigger signal can be generated in fast response to an occurrence of a true event in a high-performance manner.
[0015] The exclusion of the predetermined number of subsequently acquired sensor signals preceding the presently sampled sensor signal from the step of forming the subset can prevent replacing the presently valid first threshold value too quickly by a larger (or smaller) new presently valid first threshold value in case of sudden increase of the sensor signal, in which case a trigger signal might not be generated.
[0016] The specified sampling times may be based on a priori knowledge about a frequency range of the event to be sensed and the present noise to be expected. According to the Nyquist-Shannon sampling theorem, frequencies lower than or equal to half of a sampling frequency are perfectly reconstructible. In one embodiment, the predetermined number of subsequently acquired sensor signals to be excluded may be selected to comprise at least three periods, more preferable at least five periods, and, most preferable, at least ten periods of the highest perfectly reconstructible frequency.
[0017] Preferably, the specified sampling times are kept constant while carrying out the method. However, adjusting the specified sampling time dependent on a magnitude of the sensor signal is also contemplated. For instance, the specified sampling time could be step-wise reduced if the magnitude of the sensor signal crosses another predetermined threshold value.
[0018] If the step of acquiring the sensor signal at specified sampling times comprises digitally converting the acquired sensor signal, the benefits of well-known methods of digital signal processing apply to the subsequent steps of the method.
[0019] In a preferred embodiment of the method, the step of determining an update value for the first threshold value comprises calculating a statistical measure that is indicative of a volatility of the values of at least the formed subset of sampled sensor signals. The step of determining an update value for the first threshold value is based on the calculated statistical measure.
[0020] Examples for the statistical measure include, but are not limited to, standard deviation, variance and mean absolute deviation. Also a weighted statistical measure is contemplated, for instance a weighting based on a magnitude and/or a frequency of the sensor signal.
[0021] In this way, the noise present in the sensor signal can be considered as a whole for reliably preventing generating a false trigger due to time dependent noise.
[0022] In another preferred embodiment of the method, the step of determining an update value for the first threshold value comprises multiplying the calculated statistical measure by a predetermined constant factor, comparing the calculated product with a predetermined lower bound value, and determining an update value for the first threshold value as the maximum of the calculated product and the predetermined lower bound value.
[0023] In this way, a predetermined distance between the sensor signal comprising the wanted signal superposed by noise and the update value for the first threshold value can be kept to prevent generating a trigger signal by the noise present, meaning a false alarm.
[0024] In yet another preferred embodiment of the method, the step of determining an update value for the first threshold value comprises calculating a difference of the presently valid first threshold value and the presently sampled sensor signal, comparing the calculated difference with a predetermined distance value, calculating the update value for the first threshold value as the sum of the presently sampled sensor signal and the predetermined distance value, if the calculated difference is less than the predetermined distance value, - calculating the update value for the first threshold value as the sum of a maximum taken among a predetermined number of samples acquired before the presently sampled sensor signal and the predetermined distance value, if the calculated difference is larger than the predetermined distance value.
[0025] Also in this way, a predetermined distance between the sensor signal comprising the wanted signal superposed by noise and the update value for the first threshold value can be kept to prevent generating a trigger signal by the noise present, i.e. a false alarm can advantageously and reliably be avoided.
[0026] In a variation of this preferred embodiment of the method having similar benefits, the step of determining an update value for the first threshold value further comprises comparing the calculated update value for the first threshold value with a predetermined lower bound value, and determining an update value for the first threshold value as the maximum of the calculated update value and the predetermined lower bound value.
[0027] In another preferred embodiment of the method, the step of determining an update value for the first threshold value comprises calculating a plurality of coefficients with respect to a suitable set of decomposition vectors, for instance orthonormal vectors as they are for example used in the discrete Fourier transform, for at least the formed subset out of the sampled sensor signals, determining a highest absolute value among the calculated plurality of coefficients, determining the update value for the first threshold value as the lesser of the determined highest absolute value and a second predetermined lower bound value.
[0028] As discussed before, frequencies lower than or equal to half of the sampling frequency are perfectly reconstructible and a plurality of discrete coefficients exists up to this frequency. The plurality of coefficients with respect to a suitable set of decomposition vectors may for instance comprise orthonormal vectors as they are for example used in the discrete Fourier transform, i.e. a plurality of discrete Fourier coefficients, or wavelet coefficients or the like.
[0029] In this way, a predetermined distance between the sensor signal comprising the wanted signal superposed by noise and the update value for the first threshold value can be kept to prevent generating a trigger signal by the noise present, meaning a false alarm. This embodiment of the method is especially suitable for applying a weighting with regard to a frequency of the noise.
[0030] In another preferred embodiment of the method, the at least one sensor of the sensor system is designed as a proximity sensor, the event is formed by an operator-intended event, and the trigger signal is designed as an input to a control unit for controlling an activation of a motor-driven vehicle door member.
[0031] In this way, the benefits of the disclosed methods presented before, in particular with regard to improved performance regarding distinction of operator-intended events and noise, in particular by interfering objects and a fast response to operate-intended events apply to the method for controlling an activation of the motor-driven vehicle door member.
[0032] Preferably, the at least one proximity sensor is based on a capacitive operating principle.
[0033] In yet another preferred embodiment, the method further comprises steps of comparing the determined update value for the first threshold value with a predetermined second threshold value, and omitting to generate a trigger signal if the determined update value for the first threshold value is equal to or larger than the predetermined second threshold value.
[0034] In this way, any indication of an occurrence of an event is blocked, as a detected level of noise, for instance from electromagnetic interference or from interference with the at least one sensor and other physical objects than the operator, reached or exceeded a level that is beyond a regime for reliable operation. The predetermined second threshold value is selected appropriately, based on results of calibration measurements.
[0035] It is another object of the invention to provide a control unit for a system for generating a trigger signal for the activation of a motor-driven vehicle door member. The control unit comprises at least one processor unit and at least one digital data memory unit, wherein the at least one processor unit has data access to the at least one digital data memory unit, a sensor driving unit that is electrically connectable to at least one proximity sensor that is configured to generate a sensor signal indicative of a distance to an object, for providing a driving voltage to the at least one proximity sensor, and a sensor signal evaluation unit that is connectable to the at least one proximity sensor and is configured for receiving the sensor signal as a signal input, and is further configured for evaluating the received sensor signal by carrying out steps of an embodiment of the method as disclosed herein.
[0036] Moreover, the at least one processor unit is configured, upon and as long as receiving a trigger signal from the sensor signal evaluation unit, to carry out additional steps of detailed evaluation of the sensor signal for generating an output signal for at least initiating an activation of the motor-driven vehicle door member, based on predetermined sensor signal validation criteria.
[0037] In this way, the benefits presented before with regard to the method of operating a sensor system apply to the control unit for generating a trigger signal for the activation of the motor-driven vehicle door member. Furthermore, a level of power consumption of the control unit can be reduced by avoiding unintendedly carrying out the additional steps of detailed evaluation of the sensor signal.
[0038] In a further aspect of the invention, a software module is provided for carrying out an embodiment of the method disclosed herein, wherein the method steps to be conducted are converted into a program code of the software module that is implementable in a digital data memory unit and that is executable by a processor unit. The processor unit may preferably be the processor unit of the control unit for controlling activation of a motor-driven vehicle door member.
[0039] The software module can enable a robust and reliable execution of the method and can allow for a fast modification of method steps.
[0040] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.
Brief Description of the Drawings [0041] Preferred embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:
Fig. 1 is a schematic illustration of a control unit in accordance with the invention; Fig. 2 schematically illustrates a sensor signal generated by a proximity sensor;
Fig. 3 schematically illustrates a result of forming a subset out of a sampled sensor signal as a step of a method in accordance with the invention;
Fig. 4 is the flow scheme of the method in accordance with the invention;
Fig. 5 shows time diagrams of proximity sensor signals, a presently valid first threshold value and a status of a trigger signal to the control unit pursuant to Fig. 1 obtained during execution of a method in accordance with the invention in a situation in which no activation is triggered;
Fig. 6 shows time diagrams of proximity sensor signals, a presently valid first threshold value and a status of a trigger signal to the control unit pursuant to Fig. 1 obtained during execution of a method in accordance with the invention in a situation, where a kick is detected and a trigger signal is generated.
Description of Preferred Embodiments [0042] Fig. 1 schematically illustrates a control unit 10 for generating a trigger signal for controlling activation of a motor-driven vehicle door member in accordance with the invention. The vehicle door member is e.g. formed by a tailgate. The control unit 10 includes a processor unit 12, and a sensor driving unit 16 that is electrically connected to two proximity sensors 26, 30 for providing driving voltages to the proximity sensors 26, 30. Each one of the two proximity sensors 26, 30 is designed as a capacitive sensor that is configured to generate a sensor signal 28, 32 indicative of a sensed physical quantity given by a distance to an object, in particular a foot of an operator, as will be described later on.
[0043] The control unit 10 further comprises a sensor signal evaluation unit 18 that is connected to the proximity sensors 26, 30 and is configured for receiving the sensor signals 28, 32 as signal inputs. The connection between the control unit 10 and the proximity sensors 26, 30 may be wire-based or wireless.
[0044] A configuration of the control unit 10 and the proximity sensors 26, 30 that are arranged at locations close to the vehicle tailgate is similar to those known in the art, for instance from international application WO 2012/084111 A1 mentioned in the introductory part of this application, and shall therefore not be described in more detail herein.
[0045] The sensor signal evaluation unit 18 is equipped with a processor unit 20 and a digital data memory 22, and is configured for evaluating the sensor signals 28, 32 received by the two capacitive proximity sensors 26, 30. To this end, the sensor signal evaluation unit 18 includes a software module 24 for carrying out a method of operating a sensor system formed by the two capacitive proximity sensors 26, 30 with regard to generating a trigger signal 40 indicative of an occurrence of an event in the presence of noise. The event is formed by an operator-intended event, in particular a kick motion of an operator's foot close to the vehicle tailgate. The trigger signal 40 is designed as an input to the processor unit 12 of the control unit 10. The method steps to be conducted are converted into a program code of the software module 24, wherein the program code is implemented in the digital data memory 22 of the sensor signal evaluation unit 18 and is executed by the processor unit 12 of the sensor signal evaluation unit 18.
[0046] In the following, an embodiment of the method will be described. A flowchart of the method is illustrated in Fig. 4. In preparation of operating the control unit 10 and the two capacitive proximity sensors 26, 30, it shall be understood that all involved units and devices are in operational state and configured as illustrated in Fig. 1. Magnitudes of the signals 28, 32 of the proximity sensors 26, 30 are being monitored by the sensor signal evaluation unit 18. Execution of the method steps is started if the magnitude of one of the signals 28, 32 of the capacitive proximity sensors 26, 30 exceeds an activation threshold. After that, the method steps are automatically repeated until the magnitudes of the signals 28, 32 of the proximity sensors 26, 30 fall below the activation threshold.
[0047] Fig. 2 schematically illustrates a typical sensor signal 28, 32 generated by the capacitive proximity sensors 26, 30 over time. A magnitude of the sensor signals 28, 32 and any threshold values 36, 38 are referenced against a corresponding baseline 34 which can be considered as a signal level resulting from applying low pass filtering to the sensor signal 28, 32. A cut-off frequency of the low pass filter may e.g. be 1/10 of an expected lowest frequency of a wanted signal. For a kick motion of the operator, the expected lowest frequency can be estimated as 0.5 Hz, so that the cut-off frequency of the low pass filter may be selected to be 0.05 Hz or even lower.
[0048] Although only described for one of the capacitive proximity sensors 26, 30 in the following, the disclosed method steps are understood to be applied to each one of the two capacitive proximity sensors 26, 30.
[0049] In a first step 50 of the method, the sensor signal 28, 32 is acquired at specified sampling times, i.e. with a constant sampling rate, and the acquired sensor signal 28, 32 is digitally converted for further signal processing.
[0050] In a next step 52 of the method, a value obtained as a presently sampled sensor signal 28, 32 (denoted in Fig. 3 by the letter k) is compared with a presently valid first threshold value 36 that is stored in the digital data memory 22 of the sensor signal evaluation unit 18.
[0051] If the value obtained as the presently sampled sensor signal 28, 32 is as large as or exceeds the presently valid first threshold value 36, a trigger signal 40 is generated by the sensor signal evaluation 18 unit as a next step 54. If the value obtained as the presently sampled sensor signal 28, 32 is less than the presently valid first threshold value 36, the generation of the trigger signal 40 is omitted.
[0052] Referring to Fig. 3, in the following step 56 of the method a subset 44 is formed out of the sampled sensor signals 28, 32. A predetermined number of subsequently acquired sensor signals 42 preceding the presently sampled sensor signal 28, 32 is excluded from forming the subset 44.
[0053] Based on the formed subset 44 of sampled sensor signals 28, 32, an update value for the first threshold value 36 is determined in a next step 58. In this step 58, a statistical measure that is indicative of a volatility of the values of at least the formed subset 44 of sampled sensor signals 28, 32, namely the standard deviation, is calculated. Algorithms for conveniently calculating the standard deviation of sampled data without the need of storing the sampled data are known from literature, for example from Donald E. Knuth: "The Art of Computer Programming”. The step 58 of determining an update value for the first threshold value 36 is based on the calculated statistical measure inasmuch as the calculated standard deviation is multiplied by a predetermined constant factor, which can be a value between 3 to 6 depending on the desired sensitivity and/or noise filtering. The factor may e.g. have a value of 4.0. Further, the calculated product is compared with a predetermined lower bound value which is depending on the electronic configuration, e.g. a value of 5.0. Both the predetermined constant factor and the predetermined lower bound value are stored in the digital data memory 22 of the sensor signal evaluation unit 18. The update value for the first threshold value 36 is determined as the maximum of the calculated product and the predetermined lower bound value. As will be obvious to those skilled in the art, the standard deviation is a dimensioned quantity. For improved readability, all quantities are expressed in arbitrary units herein.
[0054] In a next step 60 of the method, the presently valid first threshold value 36 is replaced by the update value for the first threshold value 36 as a new presently valid first threshold value 36.
[0055] Then, in another step 62, the determined update value for the first threshold value 36 is compared with a predetermined second threshold value 38 that is stored in the digital data memory 22 of the sensor signal evaluation unit 18. If the determined update value for the first threshold value 36 is equal to or larger than the predetermined second threshold value 38, the signal evaluation unit 18 may determine that the level of noise exceeds a level that is beyond a regime for reliable operation, and the generation of the trigger signal 40 is omitted as a next step 64.
[0056] The disclosed steps are repeated synchronously with the specified sampling of sensor signals 28, 32.
[0057] In an alternative method in accordance with the invention, in the step 58 of determining an update value for the first threshold value 36 on the basis of the formed subset 44 of sampled sensor signals 28, 32, an update value is determined by calculating a difference of the presently valid first threshold value 36 and the presently sampled sensor signal 28, 32, comparing the calculated difference with a predetermined distance value, calculating the update value for the first threshold value 36 as the sum of the presently sampled sensor signal 28, 32 and the predetermined distance value, if the calculated difference is less than the predetermined distance value, calculating the update value for the first threshold value 36 as the sum of a maximum taken among a predetermined number of samples acquired before the presently sampled sensor signal 28, 32 and the predetermined distance value, if the calculated difference is larger than the predetermined distance value, comparing the calculated update value for the first threshold value 36 with a predetermined lower bound value, and determining an update value for the first threshold value 36 as the maximum of the calculated update value and the predetermined lower bound value.
[0058] This may for instance be accomplished by executing the following exemplary code: max/ncrease=5; minDist=1 ; L=5; H min=L; (for first sample; k=1) preliminary s=signal(k) if baseLine (k) + H min(k-1) - s< minDist H min (k) = min(s+baseLine(k)+minDist, maxlncrease:) elseif h_min has not been updated within last 20 samples H min (k)= max(x(s)-baseLine(s); s-t-20,..., t)+minDist end H min(k)= max(H min(k), L) wherein H min(k) denotes the update value for the first threshold value, determined for a current sample of the proximity sensor signals, signal(k) denotes the presently sampled sensor signal 28, 32, L denotes the predetermined lower bound value, minDist denotes the predetermined distance value, and baseLine denotes the signal baseline 34.
[0059] In a second alternative method in accordance with the invention, in the step 58 of determining an update value for the first threshold value 36 on the basis of the formed subset 44 of sampled sensor signals 28, 32, an update value is determined by calculating a plurality of discrete Fourier coefficients for at least the formed subset 44 out of the sampled sensor signals 28, 32, determining a highest absolute value among the calculated plurality of Fourier coefficients, determining the update value for the first threshold value 36 as the lesser of the determined highest absolute value and a predetermined lower bound value.
[0060] Fig. 5 shows time diagrams of the proximity sensor signals 28, 32, the presently valid first threshold value 36 and a status of the trigger signal 40 of the sensor signal evaluation unit 18 to the processor unit 12 of the control unit 10 in a situation in which no activation is triggered. The time diagram shows how the first threshold value 36 adapts to increasing noise. During the entire time window represented in Fig. 5, the raw sensor signals 28, 32 stay clearly below the first threshold value 36 and accordingly no activation signal is triggered.
[0061] Fig. 6 shows time diagrams of the proximity sensor signals 28, 32, the presently valid first threshold value 36 and a status of the trigger signal 40 of the sensor signal evaluation unit 18 to the processor unit 12 of the control unit 10 in a situation, where a kick is detected and a trigger signal is generated. This figure displays the behaviour during a usual kick.
[0062] Around the time mark of 1100, the sensor signals 28, 32 of the respective sensors cross the respective value of the first threshold value 36 and a trigger signal 40 is generated by the sensor signal evaluation unit 18 and provided to the processor unit 12 of the control unit 10, which, upon receiving the trigger signal 40, commences to carry out additional steps of the processing of kick detection. During the further processing of kick detection, the adaptive threshold 36 is still updated in the background but it is not considered during kick processing.
[0063] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments.
[0064] Other variations to be disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting scope.
Reference Symbol List 10 control unit steps of 12 processor unit 50 acquire sensor signal 14 digital data memory unit 52 compare presently sampled sensor signal with first threshold value 16 sensor driving unit 54 generate trigger signal 18 sensor signal evaluation unit 56 form subset of sampled sensor signals 20 processor unit 58 determine update value for first threshold value 22 digital data memory 60 replace valid first threshold value by update value 24 software module 62 compare update value with second threshold value 26 proximity sensor 64 omit generating trigger signal 28 sensor signal 30 proximity sensor 32 sensor signal 34 baseline 36 first threshold value 38 second threshold value 40 trigger signal 42 excluded sampled sensor signals 44 subset of sampled sensor signals 46 flag 48 control unit output signal

Claims (11)

1. Verfahren zum Betreiben eines Sensorsystems, wobei das Sensorsystem mindestens einen Sensor (26, 30) aufweist, der ein Sensorsignal (28, 32) erzeugt, das eine abgetastete physikalische Größe anzeigt, im Hinblick auf das Erzeugen eines Triggersignals (40), das ein Auftreten eines Ereignisses bei vorhandenem Rauschen anzeigt, wobei das Verfahren die folgenden sich wiederholenden Schritte umfasst: Erfassen (50) des Sensorsignals (28, 32) zu festgelegten Abtastzeiten, Vergleichen (52) eines als ein gegenwärtig abgetastetes Sensorsignal (28, 32) erhaltenen Werts mit einem aktuell gültigen Schwellenwert (36), Erzeugen (54) eines Triggersignals (40), wenn der als das aktuell abgetastete Sensorsignal (28, 32) erhaltene Wert so groß wie oder größer als der aktuell gültige erste Schwellenwert (36) ist, Auslassen der Erzeugung eines Triggersignals (40), wenn der als das aktuell abgetastete Sensorsignal (28, 32) erhaltene Wert kleiner als der aktuell gültige erste Schwellenwert (36) ist, Bilden (56) einer Teilmenge (44) aus den abgetasteten Sensorsignalen (28, 32), wobei eine vorbestimmte Anzahl an nacheinander erfassten Sensorsignalen (28, 32), die dem aktuell abgetasteten Sensorsignal (28, 32) vorausgehen, vom Bilden der Teilmenge (44) ausgeschlossen sind, basierend auf der gebildeten Teilmenge (44) der abgetasteten Sensorsignale (28, 32), Festlegen (58) eines Aktualisierungswerts für den ersten Schwellenwert (36), und Ersetzen (60) des aktuell gültigen ersten Schwellenwerts (36) durch den Aktualisierungswert für den ersten Schwellenwert (36) als neuen aktuell gültigen ersten Schwellenwert (36).A method of operating a sensor system, the sensor system comprising at least one sensor (26, 30) generating a sensor signal (28, 32) indicative of a sensed physical quantity with a view to generating a trigger signal (40) indicates an occurrence of an event in the presence of noise, the method comprising the following repetitive steps: detecting (50) the sensor signal (28, 32) at fixed sampling times, comparing (52) a sensor signal obtained as a currently sampled sensor signal (28, 32) Value having a currently valid threshold value (36), generating (54) a trigger signal (40) if the value obtained as the currently sampled sensor signal (28, 32) is greater than or greater than the currently valid first threshold value (36), Omitting the generation of a trigger signal (40) if the value obtained as the currently sampled sensor signal (28, 32) is less than the currently valid first threshold value (36) t, forming (56) a subset (44) of the sampled sensor signals (28, 32), wherein a predetermined number of sequentially detected sensor signals (28, 32) preceding the currently sampled sensor signal (28, 32) form the Subset (44) based on the formed subset (44) of the sampled sensor signals (28, 32), setting (58) an update value for the first threshold (36), and replacing (60) the currently valid first threshold (36 ) by the first threshold (36) update value as the new currently valid first threshold (36). 2. Verfahren gemäß Anspruch 1, wobei der Schritt (50) zum Erfassen des Sensorsignals (28, 32) zu festgelegten Abtastzeiten das digitale Konvertieren des erfassten Sensorsignals (28, 32) umfasst.The method of claim 1, wherein the step (50) of detecting the sensor signal (28, 32) at fixed sampling times comprises digitally converting the sensed sensor signal (28, 32). 3. Verfahren gemäß Anspruch 1 oder 2, wobei der Schritt zum Bestimmen (58) eines Aktualisierungswerts für den ersten Schwellenwert (36) folgendes umfasst: Berechnen eines statistischen Maßes, das eine Volatilität der Werte von zumindest der gebildeten Teilmenge (44) der abgetasteten Sensorsignale (28, 32) anzeigt, und wobei der Schritt zum Bestimmen (58) eines Aktualisierungswerts für den ersten Schwellenwert (36) auf dem berechneten statistischen Maß basiert.The method of claim 1 or 2, wherein the step of determining (58) an update value for the first threshold (36) comprises: calculating a statistical measure that is a volatility of the values of at least the formed subset (44) of the sampled sensor signals (28, 32), and wherein the step of determining (58) an update value for the first threshold (36) is based on the calculated statistical measure. 4. Verfahren gemäß Anspruch 3, wobei der Schritt zum Bestimmen (58) eines Aktualisierungswerts für den ersten Schwellenwert (36) Folgendes umfasst: Multiplizieren des berechneten statistischen Maßes mit einem vorbestimmten konstanten Faktor, Vergleichen des berechneten Produkts mit einem vorbestimmten unteren Grenzwert, und Bestimmen eines Aktualisierungswerts für den ersten Schwellenwert (36) als das Maximum des berechneten Produkts und des vorbestimmten unteren Grenzwerts.The method of claim 3, wherein the step of determining (58) an update value for the first threshold (36) comprises multiplying the calculated statistical measure by a predetermined constant factor, comparing the calculated product to a predetermined lower limit, and determining an update value for the first threshold (36) as the maximum of the calculated product and the predetermined lower limit. 5. Verfahren gemäß Anspruch 1 oder 2, wobei der Schritt zum Bestimmen (58) eines Aktualisierungswerts für den ersten Schwellenwert (36) Folgendes umfasst: Berechnen eines Unterschieds des aktuell gültigen ersten Schwellenwerts (46) und des aktuell abgetasteten Sensorsignals (28, 32), - Vergleichen des berechneten Unterschieds mit einem vorbestimmten Abstandswert, Berechnen des Aktualisierungswerts für den ersten Schwellenwert (36) als die Summe des aktuell abgetasteten Sensorsignals (28, 32) und des vorbestimmten Abstandswerts, wenn der berechnete Unterschied kleiner als oder gleich dem vorbestimmten Abstandswert ist, Berechnen des Aktualisierungswerts für den ersten Schwellenwert (36) als die Summe eines Maximums, das einer vorbestimmten Anzahl an Abtastwerten entnommen wird, die vor dem aktuell abgetasteten Sensorsignal (28, 32) und dem vorbestimmten Abstandswert erfasst wurden, wenn der berechnete Unterschied größer als der vorbestimmte Abstandswert ist.The method of claim 1 or 2, wherein the step of determining (58) an update value for the first threshold (36) comprises: calculating a difference of the currently valid first threshold (46) and the currently sampled sensor signal (28, 32) - comparing the calculated difference with a predetermined distance value, calculating the update value for the first threshold (36) as the sum of the currently sampled sensor signal (28, 32) and the predetermined distance value if the calculated difference is less than or equal to the predetermined distance value Calculating the update value for the first threshold (36) as the sum of a maximum taken from a predetermined number of samples acquired prior to the currently sampled sensor signal (28, 32) and the predetermined distance value if the calculated difference is greater than is the predetermined distance value. 6. Verfahren gemäß Anspruch 5, wobei der Schritt zum Bestimmen (58) eines Aktualisierungswerts für den ersten Schwellenwert (36) darüber hinaus Folgendes umfasst: Vergleichen des berechneten Aktualisierungswerts für den ersten Schwellenwert (36) mit einem vorbestimmten unteren Grenzwert, und Bestimmen eines Aktualisierungswerts für den ersten Schwellenwert (36) als das Maximum des berechneten Aktualisierungswerts und des vorbestimmten unteren Grenzwerts.The method of claim 5, wherein the step of determining (58) an update value for the first threshold (36) further comprises: comparing the calculated update value for the first threshold (36) to a predetermined lower limit, and determining an update value for the first threshold (36) as the maximum of the calculated update value and the predetermined lower limit. 7. Verfahren gemäß Anspruch 1 oder 2, wobei der Schritt zum Bestimmen (58) eines Aktualisierungswerts für den ersten Schwellenwert (36) Folgendes umfasst: Berechnen einer Vielzahl von Koeffizienten im Hinblick auf einen geeigneten Satz an Dekompositionsvektoren für zumindest die gebildete Teilmenge (44) aus den abgetasteten Sensorsignalen (28, 32), Bestimmen eines höchsten absoluten Werts aus der berechneten Vielzahl von Koeffizienten, Bestimmen des Aktualisierungswerts für den ersten Schwellenwert (36) als der niedrigere des vorbestimmten höchsten absoluten Werts und eines vorbestimmten unteren Grenzwerts.The method of claim 1 or 2, wherein the step of determining (58) an update value for the first threshold (36) comprises: calculating a plurality of coefficients with respect to an appropriate set of decomposition vectors for at least the formed subset (44) from the sampled sensor signals (28, 32), determining a highest absolute value from the calculated plurality of coefficients, determining the update value for the first threshold (36) as the lower of the predetermined highest absolute value and a predetermined lower limit. 8. Verfahren gemäß einem der Ansprüche 1 bis 7, wobei der zumindest eine Sensor (26, 30) des Sensorsystems als ein Näherungssensor (26, 30) ausgebildet ist, das Ereignis durch ein vom Bediener beabsichtigtes Ereignis gebildet wird, und - das Triggersignal (40) als eine Eingabe in eine Steuereinheit (10) zum Steuern einer Aktivierung eines motorbetriebenen Fahrzeugtürelements angelegt ist.8. Method according to one of claims 1 to 7, wherein the at least one sensor (26, 30) of the sensor system is designed as a proximity sensor (26, 30), the event is formed by an event intended by the operator, and - the trigger signal ( 40) is applied as an input to a control unit (10) for controlling activation of a motor vehicle door element. 9. Verfahren gemäß einem der Ansprüche 1 bis 8, das darüber hinaus die folgenden Schritte umfasst: - Vergleichen (62) des vorbestimmten Aktualisierungswerts für den ersten Schwellenwert (36) mit einem vorbestimmten zweiten Schwellenwert (38), und - Auslassen (64) des Erzeugens eines Triggersignals (40), wenn der vorbestimmte Aktualisierungswert für den ersten Schwellenwert (36) gleich oder größer als der vorbestimmte zweite Schwellenwert (38) ist.The method according to one of claims 1 to 8, further comprising the steps of: - comparing (62) the predetermined update value for the first threshold (36) with a predetermined second threshold (38), and - omitting (64) the Generating a trigger signal (40) if the predetermined update value for the first threshold (36) is equal to or greater than the predetermined second threshold (38). 10. Eine Steuereinheit (10) zum Erzeugen eines Triggersignals zum Steuern der Aktivierung eines motorbetriebenen Fahrzeugtürelements, wobei die Steuereinheit (10) Folgendes aufweist: mindestens eine Prozessoreinheit (12) und mindestens eine digitale Datenspeichereinheit (14), wobei die mindestens eine Prozessoreinheit (12) Datenzugang zu der mindestens einen digitalen Datenspeichereinheit (14) hat, eine Sensorantriebseinheit (16), die elektrisch mit mindestens einem Näherungssensor (26, 30) verbunden werden kann, der konfiguriert ist, um ein Sensorsignal (28, 32) zu erzeugen, das einen Abstand zu einem Objekt anzeigt, um dem mindestens einen Näherungssensor (26, 30) eine Antriebsspannung bereitzustellen, eine Sensorsignal-Auswertungseinheit (18), die an den mindestens einen Näherungssensor (26, 30) angeschlossen werden kann und zum Empfangen des Sensorsignals (28, 32) als einen Signaleingang konfiguriert ist und zum Auswerten des empfangenen Sensorsignals (28, 32) durch Ausführen der Schritte des Verfahrens gemäß einem der Ansprüche 1 bis 9 konfiguriert ist, und wobei die mindestens eine Prozessoreinheit (12) konfiguriert ist, beim Empfangen und für die Dauer des Empfangene eines Triggersignals (40) von der Sensorsignal-Auswertungseinheit (18) zusätzliche Schritte der detaillierten Auswertung des Sensorsignals (26, 30) zum Erzeugen eines Ausgangssignals (48) auszuführen, um zumindest eine Aktivierung des motorbetriebenen Fahrzeugtürelements basierend auf den vorbestimmten Sensorsignal-Validierungskriterien zu initiieren.A control unit (10) for generating a trigger signal for controlling the activation of a powered vehicle door member, the control unit (10) comprising: at least one processor unit (12) and at least one digital data storage unit (14), the at least one processor unit (12 ) Has data access to the at least one digital data storage unit (14), a sensor drive unit (16) that is electrically connectable to at least one proximity sensor (26, 30) configured to generate a sensor signal (28, 32) indicates a distance to an object in order to provide a drive voltage to the at least one proximity sensor (26, 30), a sensor signal evaluation unit (18) which can be connected to the at least one proximity sensor (26, 30) and for receiving the sensor signal (28 , 32) is configured as a signal input and for evaluating the received sensor signal (28, 32) by execution The method according to claim 1, wherein the at least one processor unit is configured to receive additional steps upon receiving and for the duration of receiving a trigger signal from the sensor signal evaluation unit performing a detailed evaluation of the sensor signal (26, 30) to generate an output signal (48) to initiate at least activation of the powered vehicle door panel based on the predetermined sensor signal validation criteria. 11. Ein Softwaremodul (24) zum Durchführen des Verfahrens gemäß einem der Ansprüche 1 bis 9, wobei die auszuführenden Verfahrensschritte in einen Programmcode des Softwaremoduls (24) umgewandelt werden, wobei der Programmcode in einem digitalen Datenspeicher (14, 22) implementierbar und mittels einer Prozessoreinheit (12, 20) ausführbar ist.11. A software module (24) for carrying out the method according to one of claims 1 to 9, wherein the method steps to be executed are converted into a program code of the software module (24), wherein the program code in a digital data memory (14, 22) implementable and by means of a Processor unit (12, 20) is executable.
LU92933A 2015-08-24 2015-12-24 Adaptive signal threshold for triggering kick detection LU92933B1 (en)

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LU92933A LU92933B1 (en) 2015-12-24 2015-12-24 Adaptive signal threshold for triggering kick detection
PCT/EP2016/069639 WO2017032693A1 (en) 2015-08-24 2016-08-18 Adaptive signal threshold for triggering kick detection
US15/753,794 US10432194B2 (en) 2015-08-24 2016-08-18 Adaptive signal threshold for triggering kick detection
DE112016003831.3T DE112016003831T5 (en) 2015-08-24 2016-08-18 Adaptive signal threshold for triggering a kicker detection
CN201680048867.1A CN107925405B (en) 2015-08-24 2016-08-18 The method for generating the self-adapting signal threshold value for triggering foot-operated detection

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US20110156800A1 (en) * 2008-09-19 2011-06-30 Atlab Inc. Sensor, sensing method thereof, and filter therefor

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* Cited by examiner, † Cited by third party
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US20110156800A1 (en) * 2008-09-19 2011-06-30 Atlab Inc. Sensor, sensing method thereof, and filter therefor

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