FR2807843A1 - System for detecting the presence of a person or animal in the boot of an automotive vehicle, or back of a cargo truck, uses an acoustic signal analysis unit to detect the presence - Google Patents

Abstract

The arrangement includes a unit, which emits an acoustic signal of a certain predetermined frequency, and a receiver in the boot for detecting the reflected signal. There is an analysis unit, which analyses the reflected acoustic signal to determine the presence of a person or animal in the boot.

Description

<U> IMPROVEMENTS IN THE </ U> <U> DETECTION OF THE <U> PRESENCE <U> OF A PERSON OR ANIMAL IN A </ U> VEHICLE <U> AUTOMOBILE </ U> The present invention relates to the detection of the presence of a person or an animal in a trunk of a motor vehicle.

There are more and more accidents, particularly in the United States, caused by the fact that an animal / a person has been locked up in a motor vehicle trunk.

To avoid this type of accident, many solutions have already been proposed.

In particular, it is already known to equip the motor vehicle trunks buttons or handles inside (e) s can easily be operated by a person located inside the trunk.

In particular, there are known systems with fluorescent handle positioned inside the trunk in the vicinity of the lock.

This solution has the merit of being particularly simple, but is not fully satisfactory.

In particular, it does not allow to be warned, outside the trunk, that a person is in trouble, locked in it.

This solution is also ineffective in the case where it is an animal that is locked inside the trunk.

Moreover, because it is a totally mechanical solution, it poses certain reliability problems.

Fluorescence also poses reliability problems over time.

An alternative solution to fluorescence could be to keep the trunk permanently lit, especially when the vehicle is stationary. This would, however, pose problems of energy consumption. Systems are also known that detect the presence of a person or an animal by detecting its infrared emissions.

Such systems are also not fully satisfactory, since they are easily disturbed by the presence of parasitic heat sources.

Finally, it has also been proposed to equip motor vehicle boxes with motion detectors.

However, the sensors proposed for this type of applications to date, such as the SmartRelease (registered trademark) of DONNELLY Corporation, remain very complex and expensive.

An object of the invention is to provide a solution for the detection of people locked in a trunk of a motor vehicle that does not have the aforementioned drawbacks and is particularly reliable and effective.

The solution proposed by the invention is a device for detecting the presence of a person or an animal in a trunk of a motor vehicle comprising motion detection means, characterized in that these motion detection means comprise: acoustic transmission means which emit in the trunk a signal with at least one given acoustic frequency and first reception means which detect in the trunk an acoustic signal resulting from the emission and reflection in the trunk of the acoustic signal emitted at this frequency, as well as means for processing the signal thus detected in order to deduce information relating to the possible presence of a person or an animal in the trunk, - additional detection means, the means of processing generating a presence detection signal function of both the signal transmitted to said processing means by the first means of acoustic detection and the signal transmitted to said processing means by the complementary detection means. Such a device is advantageously completed by the following different characteristics taken alone or in all their possible combinations - the complementary detection means comprise an infrared detector.

the complementary detection means comprise a detector of the radar type.

the acoustic transmission means emit in the trunk a signal with at least a second given acoustic frequency, the complementary detection means comprise second reception means which detect in the trunk an acoustic signal resulting from the transmission and reflection in the trunk of the acoustic signal emitted at this second frequency and the processing means comprise means for comparing characteristics of the signals output from the first and second reception means and for generating a presence detection signal as a function of this comparison.

the characteristics compared are the frequency and / or phase shift of the signals received by the first and second reception means, said reception means comprising demodulation means able to determine the frequency and / or phase shift of said signals.

the demodulation means comprise IQ demodulation means.

The invention also proposes a method for detecting the presence of a person or an animal in a trunk of a motor vehicle according to which a motion detection is implemented, characterized in that this motion detection implements an acoustic emission in the trunk of a signal with at least one given acoustic frequency, a reception for detecting in the trunk an acoustic signal resulting from the emission and reflection in the trunk of the acoustic signal emitted at this frequency, and that a signal thus detected treatment in order to deduce information relating to the possible presence of a person or an animal in the trunk, - a complementary detection, and in that one detects the presence of a person or animal in function of both this complementary detection and the detection in the trunk of the acoustic signal resulting from the transmission and reflection in the trunk of the acoustic signal emitted at the aforementioned frequency.

Other features and advantages of the invention will become apparent from the description which follows, which is purely illustrative and nonlimiting and which should be read with reference to the accompanying drawings, in which: - Figure 1 is a schematic representation illustrating the principle of detection according to a possible embodiment of the invention; FIGS. 2a and 2b illustrate the principles of two possible embodiments of the invention; FIG. 3 diagrammatically illustrates a detection device according to one possible embodiment for the invention; FIG. 4 is a block diagram illustrating various alternative embodiments of the invention; FIG. 5 illustrates the vector operation of the detector subsystem.

There is shown schematically in Figure 1 a vehicle V and the trunk C thereof, with a person P enclosed in its interior.

This chest C is equipped with a motion detection device symbolized in this figure 1 by two Cd sensors disposed opposite one another, on two side walls of the trunk.

This detection device is particularly capable of detecting the movements of a person or an animal inside the trunk (breathing movements, limb movements, etc.).

Management means that the vehicle is equipped activate this detection device when the trunk is closed and the vehicle is stopped.

When the vehicle is running or its engine is running, these management means deactivate the detection device.

The user also has the option to disable it on his own, when the vehicle is stopped. When the device is activated and a movement of a person or an animal is detected in the trunk, it transmits a detection signal to the aforementioned management means, which can implement the different actions.

In particular, the management means can activate a buzzer or light inside the cabin of the vehicle (indicator located on the dashboard for example) or outside (light or light guide disposed on the bodywork, in the immediate vicinity of the trunk lock, hazard warning lights, audible alarm, etc.).

Detecting a presence may also trigger the automatic boot opening or release the tilt of the rear seat to allow the person or animal stuck in the trunk to access the passenger compartment of the vehicle.

Detecting the presence of a person can also trigger an air intake into the trunk.

It can also trigger an automatic phone call to a rescue center.

Examples of detection devices will now be described.

According to a first possible embodiment, more particularly illustrated in FIG. 2a, the device comprises means E for transmitting, inside the trunk, at least one acoustic signal at a given frequency F and means R for receiving and processing acoustic signals reflected inside the trunk.

In the case where a person or an animal is inside the trunk, the transmitted signal is reflected by this person or animal and its movements (breathing movements or other symbolized by the speed V in the figure) will introduce a frequency shift aF ;.

The reception means R will process the acoustic signal they receive to detect this frequency difference OF ;. Means of reception that may be used are for example those which have been described, for a different application, in the patent application FR 2 767 948 of the applicant.

However, the detections implemented in this way may be disturbed by external noises (thermal shock, sound noise, mechanical impact on the vehicle, etc.), which are likely to generate in certain cases frequency variations of the same order of magnitude. than those corresponding to a movement.

To overcome this drawback, the proposed device implements a second detection intended to make it possible to invalidate or confirm the detections made by the ultrasonic detection means.

For this purpose, the trunk is also equipped with at least one IR detector or a radar detector.

In order to determine whether or not a presence of an animal or a person is detected, a weighted vote processing is implemented between the outputs of the different detectors.

Alternatively also, it can be provided that the ultrasonic detector covers, as illustrated in Figure 2b ultrasonic detection by means of two frequencies.

The emitter E then emits acoustic waves at frequencies FI and F2. These acoustic waves emitted inside the trunk are reflected inside the trunk and, where appropriate, on the person or animal enclosed, the receiver receiving a signal which is a combination of the waves emitted and reflected inside the trunk.

In the case where a person is locked inside of it, its movements will generate frequency offsets (AF, for the frequency F1, aF2 for the frequency F2). Since the frequencies F1 e F2 are different, these two frequency offsets - due to the Doppler effect - will themselves be different. On the other hand, in the case where the ultrasonic signals are disturbed by noises of the type mentioned above, the frequency offset detected for one or the other of the two frequencies will be identical.

The double determination of the frequency shifts aF, and AF2 thus makes it possible to distinguish a movement due to the presence of a person or an animal in the trunk, of a noise generated by an external disturbance.

The processing means then implement a comparison on the frequency and / or phase shift on the signals received by the receiver R and corresponding to the frequencies F1 and F2. A detailed exemplary embodiment will now be described.

As shown in FIG. 3, it comprises a first signal generator 2 which generates a signal I at a first frequency f 1, for example 70 kHz. The signal profile is a square wave.

This signal I supplies two other components: the first is a first division unit by two 4, which serves to reduce the frequency of the signal by half so that it becomes a square signal 3 of frequency f3, where f3 = (612) and is for example 35kHz.

The purpose of this division of the frequency fi by a factor of two is to provide a clock for sampling a signal reflected at the frequency f3, as described later.

Sampling is performed by a first IQ demodulator 26, whose function will be described below, synchronized by the clock signal 1.

The signal 3 of frequency f3 produced by the first divider 4 is received by two other components: a first RC 6 filter which converts it into a sawtooth signal of frequency f3, and a first IQ demodulator 26 which uses the signal as described below.

This sawtooth signal produced by the first RC filter 6 supplies a first scielsinusôidal tooth converter 8 which smooths the signal by converting it into a sinusoidal signal 7 of frequency f3.

This signal 7 feeds a first input of an adder / amplifier 18. A second input of the adder / amplifier 1 @ 8 is produced analogously by components similar to those described above.

A second signal generator 10 produces a signal 9 at a second frequency f2, for example 92kHz, and having a square wave profile. This signal 9 feeds two other components: a second division unit by two 12 which reduces by half the frequency of the signal 9, which therefore becomes a square signal 11 of frequency f4, where f4 = (fl2) and is for example 46kHz.

This signal 11 will be used to sample a reflected signal at a frequency f2, as described below.

The second component is a second IQ demodulator 30, whose function will be described below, synchronized by the signal which serves as a clock signal.

This signal 11 of frequency f4 produced by the second divider 12 is received by two other components: a second RC filter 14 which converts it into a sawtooth signal of frequency f4, and a second demodulator IQ 30 which uses the signal as described below.

This sawtooth signal 13 produced by the second RC filter 14 feeds a second sawtooth / sine-wave converter 16 which smooths the signal by converting it into a sinusoidal signal of frequency f4.

This signal 15 supplies the second input of the adder / amplifier 18.

 The adder / amplifier 18 adds the signals 7 and 15 to produce a resultant signal on two frequencies. The adder / amplifier 18 comprises an amplifier which amplifies the resulting signal 17.

This signal 17 supplies the ultrasonic transmitter 20 which emits it as an acoustic signal inside the vehicle. It would also be possible to transmit two separate signals each from their own transmitter.

The transmitter 20 and the receiver 22 are positioned at a suitable location inside the vehicle, so that the transmitted signal reaches the greater part of the interior of the vehicle, for example under the roof of the vehicle.

The dual frequency signal is emitted over a wide angle to reach many different surfaces inside vehicles. The signal is reflected by and between these surfaces to be finally received by a receiver 22.

In order to simplify the installation, the receiver 22 could be placed near the transmitter 20, provided that the receiver is not flooded with signals received directly from the transmitter without reflection inside the vehicle.

The reflection of the surfaces changes the phase and amplitude of the resulting signals for each of the components (f3 and f4) of the dual frequency signal, each surface and reflection causing a different change.

The resulting signals therefore depend on the path length between the transmitter at the reflective surface and behind the receiver, and the nature of the surfaces.

The overall signal received by the receiver 22 is the sum of all the different signals reflected from the different surfaces.

It can be said that each component, the sinusoidal origin signals 7 and 15, is modulated by its passage through the vehicle from the transmitter (s) and the receiver (s).

In the case of the presence of a person or an animal in the vehicle, the movements will modify the basic answer of the space by disturbing all the reflections.

Thus it is likely that the received signals are modified.

Signals received may also be altered by false alarm factors, such as small vehicle window deflections due to shock waves when passing near other vehicles, or sources of high frequency acoustic interference. outside the vehicle.

The received signals are therefore analyzed to determine whether the reference response has actually changed and, in this case, whether the change presumably indicates an intrusion that requires the triggering of an alarm.

From the received dual frequency signal modulated by these components, the receiver 22 generates a corresponding data signal 23.

This signal 23 supplies a first filter and a second filter.

The first filter is a bandpass filter which is only passing in a frequency band around 10 kHz for example, thereby producing a data signal from the modulated signal 7 of frequency f3.

The second filter is a bandpass filter that is only passing in a frequency band around f4, 10kHz for example, thereby producing a data signal 27 from the modulated signal of frequency f4.

The signals 25, 27 may be optionally amplified.

The signal 25 of the data channel at f3 feeds the first IQ demodulator 26 where it is sampled at f1, synchronized by the clock signal 1.

Since the square wave signal 3 at frequency f3 also supplies the first IQ demodulator 26, it is possible to obtain only the modulation of the original signal f3 by means of the transformation of the signal 3 with the signal 25. This calculated signal is then demodulated to obtain a first component in phase II and a first component in quadrature Ql. These components II and Q can be considered respectively as the real and imaginary parts of the modulation of the signal 25.

They represent a first stable vector for the interior of the vehicle, which means that they represent the phase modulation of the first transmitted sinusoidal signal 7 in the absence of an intrusion into the vehicle. Components II and Q, at the output of the first IQ demodulator 26, supply a microprocessor 32. Similarly, the signal 27 of the 46 kHz data channel supplies the second IQ demodulator 30, where it is sampled at f2, synchronized by the signal clock 9.

Since the square wave signal 11 at frequency f4 also supplies the second IQ demodulator 30, it is possible to obtain only the modulation of the original signal f4 by means of the signal transformation 11 with the signal 27.

This calculated signal is then demodulated to obtain a second phase component 12 and a second quadrature component Q2. These components 12 and Q2 can be considered respectively as E real and imaginary parts of the modulation of the signal 27. They represent a second stable vector for the interior of the vehicle, which means that they represent the phase modulation of the second signal sinusoidal transmitted 15 in the absence of intrusion into the vehicle. These components 12 'and Q2 at the output of the second IQ demodulator 30 feed the microprocessor 32.

If the inside of the vehicle is changed in any way, due to movement, the first and second stable vectors will have additional perturbation components.

This effect can be seen schematically in FIG. 4, which shows a stable vector S and several perturbation vectors, such as P.

The function of such disturbance vectors in determining the presence of an intruder will now be described in more detail, in particular with reference to the operation of the microprocessor 32.

In FIG. 3, it can be seen that the signal Il is periodically acquired by a first acquisition unit 34 and that the signal QI is periodically acquired by a second acquisition unit 36.

In a first acquisition of the signals, a first signal acquired in phase and a first signal acquired in quadrature feed a first angle resolver 38. The angle resolver 38 comprises a memory which stores the first signal acquired in phase and the first signal These signals represent the stable vector for the interior of the vehicle, vector equivalent to the vector 80 in Figure 4 representing a stable state, which signals are stored during the autonomous phase. after the activation of the device, during which the device waits for a stable state to be established, or calculates the average of the received signals I1 and Q1 over an initial period, and then stores these average values of 11 and IQ in the angle resolver 38.

In monitoring mode, a phase II signal and a quadrature QI signal are acquired periodically.

These signals together represent a current vector for the interior of the vehicle. The reference values of the in-phase signal and the quadrature signal are read from the memory of the angle resolver 38.

These are subtracted from newly acquired signals to determine the deviation vector of the new signals from the reference steady state. This is the equivalent of the perturbation vector 81 in FIG.

The angle resolver also determines the angular deviation in the I-Q space of this deflection vector from the immediately preceding deflection vector.

A first comparator 40 calculates the phase angle difference between the deflection vector and the previous deflection vector.

Then, the previous deflection vector in the previous angle unit 42 is replaced by the current deflection vector for use in the next cycle.

This process is repeated at the next acquisition. A new signal acquired in phase and a new signal acquired in quadrature are then stored in the memory, thus constituting a new vector for the interior of the vehicle. The second signal acquired in phase and the second signal acquired in quadrature are read from the memory.

The comparator 40 calculates the phase difference between the second and third vectors.

In general, at each acquisition, the newly acquired phase and quadrature signals represent a vector for the interior of the vehicle. The phase difference between this vector and the preceding vector (marked previous angle 42 in FIG. 4) is calculated by the comparator 40. This difference is designated by angular delta 44 in FIG.

Whenever a phase difference is calculated, a counter is incremented by the angular delta 44.

This operation is referenced 46 in FIG. 3. The counter can be considered as a first cumulative angle 48. At the first acquisition, it is set to zero because this value represents the notional phase angle of the stable vector.

At each subsequent acquisition, the angular delta is added to the previous cumulative angle 50.

In the absence of movements in the trunk, the signals Il and Q, will be unchanged at each acquisition, so the previous angle 42 will be equal to each newly acquired phase angle.

Consequently, the angular delta will be zero, the counter will not be incremented and the cumulative angle 48 will remain zero.

On the other hand, if there is a disturbance inside the trunk, the component f3 of the double acoustic frequency signal will be reflected differently because of the disturbance, so the modulation of the signal produced will differ from that produced when it does not. there is no disturbance.

Since the overall modulation of the signal f3 is changed, the signal supplying the first IQ demodulator 26 will have a phase angle different from that of the stable signal.

Therefore, the components II and Q change and upon acquisition by the units 34, 36 and the signal transferred to the angle resolver 38, the phase angle will differ from the previous angle 42 and the angular delta 44 will no longer be zero, the cumulative angle 48 then being incremented by the angular delta 44.

This process is repeated at each acquisition. Each time the angular delta 44 will change and will be added to the cumulative angle 48.

When a disturbance is caused by the movement of a person or animal in the trunk, the angular delta will tend to increase gradually with the same sign while the intruder enters the vehicle.

However, there are certain types of noise that could also cause an increase in the same direction of the angular delta, for example a low frequency noise whose source is outside the vehicle.

It is important that this type of noise does not trigger false alarms.

An advantage of this embodiment of the present invention is that the same process of acquiring and calculating the angular delta is performed for the second component f4 of the dual acoustic frequency signal, as shown in FIG.

For this purpose, a third and a fourth acquisition unit 52, 54 are provided which receive acquired signals and whose output signals supply a second angle resolver 56 which includes a memory 60 used to store the previous angle.

A second comparator 58 is provided that calculates the angular delta 62 and adds it to the previous angle 68 to compute a second cumulative angle 66, this cumulation process being referenced 64 in FIG.

After each acquisition, the first cumulative angle 48 and the second cumulative angle 66 are received by a threshold detection unit 70 whose function is to determine whether to trigger an alarm, decision subject to two criteria.

The first criterion, which represents an advantage over the prior art, is that the first and second cumulative angles must be linked by a predetermined relationship.

When a person or an animal moves or breathes in the trunk, the angular change of the reflected sound signal of the first component at f3 will normally differ from that of the second component at f4, given their different wavelengths.

On the other hand, in the case of a disturbance signal present in the vehicle, such as a low frequency sound wave originating outside the vehicle, the two acoustic components should undergo the same modulation, and the angular deltas 44, 62 as well as the cumulative angles 48, 66 will be equal.

Thus the first criterion may be that the first and second angles differ by a threshold value, for example 1, 2 or 3 revolutions. The second criterion requires that the movement be of sufficient magnitude.

This ensures a certain number of revolutions of each angular delta and will therefore be verified by comparing each value of the cumulative angle with a predetermined threshold value stored in the threshold detecting unit 70.

This criterion provides a second safeguard against the risk of a false alarm triggered by small movements, such as those of an insect.

If both criteria are satisfied, namely that the angles 48 and 66 exceed respective thresholds and differ by more than another threshold, it is then necessary to trigger an intrusion signal, for example an alarm.

The thresholds may be stored in a memory accessible to the threshold detection unit 70 which comprises the means necessary to process its inputs and make the decision to trigger the alarm.

The thresholds may be adjustable in the factory or by the user to allow a control of the sensitivity of the system.

Moreover, the thresholds could be dynamically adjustable by the device itself, in which case one or more of the thresholds will be automatically increased to cope with particularly problematic environments, for example the proximity of a road where the jolts caused by the Passing other vehicles causes frequent alarms if the initial threshold settings are maintained.

The present invention provides two additional protections against the triggering of false alarms.

The first is that a null window threshold is provided on the values of <B> 11, </ B> Q1, 12 and Q2. Once a stable vector has been calculated, if the subsequent values are below certain threshold values, the calculation of the angular delta and the following calculation are not performed.

This prevents the accumulation of tiny disturbance effects in cumulative angle values 48, 66.

Here again, these thresholds can be adjustable as described above.

The second protection against false alarms is to impose the following rule: if an increase of the angular delta 44, 62 is detected, the increase must take place no later than a certain number of subsequent acquisitions, otherwise the angle Cumulative 48, 66 is reset.

This avoids the possibility of accumulation of small disturbances not due to an intrusion, which could trigger an alarm after a certain time.

One way to ensure this function is to decrement at a regular interval the value of the cumulative angle of each channel to be zero after a certain time.

Preferably, the frequencies of the two channels differ by more than 5 kHz, a difference of 10 kHz still being preferable.

Claims (11)

<U> CLAIMS </ U> 1. Device for detecting the presence of a person or an animal in a trunk of a motor vehicle comprising motion detection means, characterized in that these motion detection means comprise - acoustic emission means which emit in the trunk a signal with at least one given acoustic frequency and first reception means which detect in the trunk an acoustic signal r resulting from the emission and reflection in the trunk of the acoustic signal emitted at this frequency, as well as means for processing the signal thus detected in order to deduce information relating to the possible presence of a person or an animal in the trunk, - additional detection means, the processing means generating a detection signal function of both the signal transmitted to said processing means by the first acoustic detection means and the tran smis said processing means by the complementary detection means. 2. Device according to claim 1, characterized in that the complementary detection means comprise an infrared detector. 3. Device according to claim 1, characterized in that the complementary detection means comprise a radar type detector. 4. Device according to claim 1, characterized in that the acoustic transmission means emit in the trunk a signal with at least a second given acoustic frequency, in that the complementary detection means comprise second reception means which detect in the trunk an acoustic signal resulting from the emission and reflection in the trunk of the acoustic signal emitted at this second frequency and in that the processing means comprise means for comparing characteristics of the signals output from the first and second reception means and to generate a presence detection signal based on this comparison. 5. Device according to claim 4, characterized in that the characteristics compared are the frequency and / or phase shift of the signals received by the first and second receiving means, said receiving means comprising demodulation means adapted to determine the offset. frequency and / or phase of said signals. 6. Device according to claim 5, characterized in that the demodulation means comprise demodulation means IQ. 7. A method for detecting the presence of a person or an animal in a trunk of a motor vehicle according to which a motion detection is implemented, characterized in that this motion detection uses an acoustic emission in the trunk of a signal with at least one given acoustic frequency, a reception for detecting in the trunk an acoustic signal resulting from the emission and reflection in the trunk of the acoustic signal emitted at this frequency, as well as a treatment on the signal thus detected in order to deduce information relating to the possible presence of a person or an animal in the trunk, - additional detection, and in that it detects the presence of a person or an animal according to both this complementary detection and detection in the trunk of the acoustic signal resulting from the emission and reflection in the trunk of the acoustic signal emitted at the aforementioned frequency. 8. Method according to claim 7, characterized in that the complementary detection is an infrared detection. 9. The method of claim 7, characterized in that the complementary detection is radar type. 10. Process according to claim 7, characterized in that a signal is transmitted in the trunk to at least a second given acoustic frequency, in that the complementary detection implements a reception to detect in the trunk an acoustic signal resulting from the transmission and reflection in the trunk of the acoustic signal emitted at this second frequency and in that the processing implements a comparison of the characteristics of the signals output from the first and second reception means, to detect the presence of a person and / or animal. 11. The method of claim 10, characterized in that the characteristics compared are the frequency and / or phase shift of the received signals.