Method of monitoring a vehicle interior

• US 5,677,666 A
• Filed: 07/16/1996
• Issued: 10/14/1997
• Est. Priority Date: 09/08/1995
• Status: Expired due to Fees

• Current Assignee: Kiekert AG (Lingyun Industrial Corporation Limited)
• Original Assignee: Kiekert AG (Lingyun Industrial Corporation Limited)
• Inventors: Stallbohm, Uwe
• Primary Examiner(s): Swann, Glen
• Application Number:
  US08/682,979
• Time in Patent Office: 455 Days
• Field of Search: 340/426, 340/544, 340/552, 340/553, 340/554, 367/93, 367/94
• US Class Current: 340/426.27
• CPC Class Codes: B60R 25/1009 Sonic sensors; Signal treatment therefor
• CPC Class Codes: G01S 15/04 Systems determining presence of a target
• CPC Class Codes: G01S 15/88 Sonar systems specially adapted for specific applications seismic or acoustic prospecting or detecting G01V1/00
• CPC Class Codes: G01S 7/527 Extracting wanted echo signals Doppler systems G01S15/50
• CPC Class Codes: G08B 13/1618 using ultrasonic detection means

Abstract

The interior of an automotive vehicle is monitored for incursion by launching primary sound wave pulses into the interior of the vehicle and picking up the primary sound wave pulse together with superimposed reflection and sound signals generated by incursion, etc. The picked-up sound waves are transformed into electrical signals which are decomposed in an A/D converter into a time sequence of digital measurement vector elements which in turn are compared with reference elements by a subtraction process to produce a different vector. Summation of the positive terms of the difference vector and summation of the negative terms of the difference vector to produce positive and negative sums allow the sums to be combined to form a gradient which is added to previous gradients to provide a gradient sum. The alarm is triggered when the gradient sum exceeds a threshold.

Claims

1. A method of monitoring an interior of an automotive vehicle for incursion utilizing an alarm system having at least one sound emitter controlled by a computer unit for repetitive launching of primary sound wave pulses into the interior of the motor vehicle, a sound receiver for picking up sound waves in the vehicle interior including the primary sound wave pulses and reflected other waves superimposed thereon and for converting received sound waves into corresponding electrical signals, an amplifier connected to said sound receiver for amplifying said electrical signals, and an analog/digital converter connected between said amplifier and said computer unit for converting said electrical signals with a scanning rate a into digital measurement vectors, said method comprising the steps of:

(a) decomposing each of said electrical signals in said analog/digital converter into a time sequence of x digital measurement vector elements n₁ . . . n_x representing a measurement vector V for each of a succession of measurement signals, with the measurement vector element n₁ being formed when the respective electrical signal rises above a predetermined rest signal level and the measurement vector element n_x being formed when the respective electrical signal falls below said predetermined rest signal level;

(b) storing the sequence of x digital measurement vector elements n₁ . . . n_x in a memory of said computer unit having p storage locations;

(c) comparing each measurement vector V stored in said memory with a previously stored reference vector R with respective reference vector elements n'"'"'_-1 . . . n'"'"'_-x and forming a difference vector D with difference vector elements d₁ . . . d_x by subtraction of the elements n₁ . . . n_x and n'"'"'_-1 . . . n'"'"'_-x ;

(d) adding all positive ones of said difference vector elements to form a positive sum S₊ and all negative ones of said difference vector elements to form a negative sum S_- ;

(e) combining said positive sum and said negative sum additively to form a gradient of value G and adding values of the gradient together with gradient values of subsequent measurement signals, thereby forming a gradient sum; and

(f) activating said alarm upon said gradient sum exceeding a predetermined alarm threshold.

2. The method defined in claim 1 wherein said scanning rate a is reduced when the number x of the measurement vector elements exceeds the number p of storage locations of the measured value memory, and the scanning rate a is increased when the number x falls below p/2.

3. The method defined in claim 1 wherein a measurement vector V is stored in a reference memory of said computer unit as a new reference vector R when a gradient value GT exceeds a predetermined drift threshold.

4. The method defined in claim 1 wherein a measurement signal, prior to conversion into a digital measurement vector, is transformed in a rectifier into an envelope-curve measurement signal.

5. The method defined in claim 1 wherein measurement signals are obtained from a plurality of sound receivers at different locations in said vehicle, further comprising the steps of multiplexing the measurement signals from said receivers to said computer unit, thereby forming trains of measurement vector elements and feeding each train representing a measurement signal vector to a respective measurement signal memory associated with a respective reference vector memory.