Adaptive signal threshold for triggering kick detection

• US 10,432,194 B2
• Filed: 08/18/2016
• Issued: 10/01/2019
• Est. Priority Date: 08/24/2015
• Status: Active Grant

• Current Assignee: IEE International Electronics & Engineering SA (Aerospace Hi-Tech Holding Group Company Limited)
• Original Assignee: IEE International Electronics & Engineering SA (Aerospace Hi-Tech Holding Group Company Limited)
• Inventors: Bar, Johann, Anti, Baptiste, Beise, Hans Peter, Stifter, Thomas
• Primary Examiner(s): Han, Charles J
• Application Number:
  US15/753,794
• Publication Number:
  US 20180248545A1
• Time in Patent Office: 1,139 Days
• CPC Class Codes: E05F 15/73 responsive to movement or presence of persons or objects
• CPC Class Codes: E05Y 2400/32 Position control, detection or monitoring
• CPC Class Codes: E05Y 2400/44 Sensors therefore E05Y2400/322, E05Y2400/33, E05Y2400/55, E05Y2400/56, E05Y2400/852 take precedence
• CPC Class Codes: E05Y 2400/858 by body parts
• CPC Class Codes: E05Y 2900/546 Tailgates
• CPC Class Codes: G01D 5/24 by varying capacitance
• CPC Class Codes: H03K 17/945 Proximity switches H03K17/96 takes precedence
• CPC Class Codes: H03K 2217/94026 Automatic threshold calibration; e.g. threshold automatically adapts to ambient conditions or follows variation of input
• CPC Class Codes: H03K 2217/94031 Calibration involving digital processing

Abstract

A method of operating a sensor system having at least one proximity sensor, with regard to generating a trigger signal indicative of an occurrence of an operator-intended event in the presence of noise. The method includes 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 or equal to the presently valid first threshold value, forming a subset out of the sampled sensor signals, determining an update value for the first threshold value, and replacing the presently valid first threshold value by the update value.

Claims

1. A method of operating a sensor system with regard to generating a trigger signal indicative of an occurrence of an operator-actuated event in the presence of noise, the sensor system including at least one proximity sensor that generates a sensor signal indicative of a sensed physical quantity and a control unit having an evaluation unit, the method comprising steps of:

acquiring, via the evaluation unit, sample values of the sensor signal at a predetermined sampling interval,

comparing, via the evaluation unit, a presently sampled value acquired as a presently sampled sensor signal with a first threshold value stored in a memory of the evaluation unit,

generating, via the evaluation unit, the trigger signal for controlling a motor-driven vehicle door member when the value obtained as the presently sampled sensor signal is as large as or exceeds the first threshold value,

omitting to generate, via the evaluation unit, the trigger signal when the value obtained as the presently sampled sensor signal is less than the first threshold value,

forming, via the evaluation unit, a subset out of the sampled values of the sensor signals, wherein a predetermined number of consecutively acquired sensor signals immediately preceding the presently sampled value are excluded from forming the subset,

based on the formed subset of sampled sensor signals, determining, via the evaluation unit, an update value for the first threshold value, and

adapting the first threshold value to the presence of noise, via the evaluation unit, by setting the first threshold value stored in the memory of the evaluation unit equal to the update value.

2. The method as claimed in claim 1, wherein the step of acquiring, via the evaluation unit, the sensor signal at a predetermined sampling interval comprises digitally converting the acquired sensor signal.

3. The method as claimed in claim 1, wherein the step of determining, via the evaluation unit, 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,

and wherein the step of determining, via the evaluation unit, an update value for the first threshold value is based on the calculated statistical measure.

4. The method as claimed in claim 3, wherein the step of determining, via the evaluation unit, an update value for the first threshold value comprises

multiplying the calculated statistical measure by a predetermined constant factor,

comparing a calculated product of the multiplication 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.

5. The method as claimed in claim 1, wherein the step of determining, via the evaluation unit, an update value for the first threshold value comprises

calculating a difference of the 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, when the calculated difference is less than or equal to 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, when the calculated difference is larger than the predetermined distance value.

6. The method as claimed in claim 5, wherein the step of determining, via the evaluation unit, 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.

7. The method as claimed in claim 1, wherein the step of determining, via the evaluation unit, an update value for the first threshold value comprises

calculating a plurality of coefficients based on a set of decomposition vectors 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 predetermined lower bound value.

8. The method as claimed in claim 1, further comprising steps of:

comparing, via the evaluation unit, the determined update value for the first threshold value with a predetermined second threshold value, and

omitting to generate, via the evaluation unit, a trigger signal when the determined update value for the first threshold value is equal to or larger than the predetermined second threshold value.

9. A control unit for generating a trigger signal for controlling activation of a motor-driven vehicle door member, the control unit comprising:

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,

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 indicative of an operator-actuated event, and is configured for evaluating the received sensor signal by;

sampling values of the sensor signal at a predetermined sampling interval,

comparing a presently sampled value acquired as a presently sampled sensor signal with a threshold value stored in a memory of the sensor signal evaluation unit,

generating the trigger signal when the value obtained as the presently sampled sensor signal is as large as or exceeds the threshold value,

omitting to generate the trigger signal when the value obtained as the presently sampled sensor signal is less than the threshold value,

forming a subset out of the sampled sensor signals, wherein a predetermined number of consecutively acquired sensor signals immediately preceding the presently sampled sensor signal are excluded from forming the subset,

based on the formed subset of sampled sensor signals, determining an update value for the threshold value, and

adapting the threshold value to the presence of noise by setting the threshold value stored in the memory of the evaluation unit equal to the update value,

wherein the at least one processor unit is configured to generate an output signal upon and as long as the trigger signal is being received from the sensor signal evaluation unit, wherein the output signal controls the motor-driven vehicle door member based on predetermined sensor signal validation criteria.

10. A non-transitory digital data memory on which is stored a software module comprising computer-readable program code that is executable by a processor unit and configured to:

receive a sensor signal indicative of an operator actuated event from at least one proximity sensor;

sample the sensor signal at specified sampling times,

compare a value obtained as a presently sampled sensor signal with a stored threshold value,

generating a trigger signal controlling a motor-driven vehicle door member when the value obtained as the presently sampled sensor signal is as large as or exceeds the stored threshold value,

omitting to generate the trigger signal if the value obtained as the presently sampled sensor signal is less than the stored threshold value,

forming a subset out of the sampled sensor signals, wherein a predetermined number of consecutively acquired sensor signals immediately 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 stored threshold value, and

adapting the threshold value to the presence of noise by setting the stored threshold value equal to the update value.