EP0661679B1 - Method for adjusting an alarm module, in particular an ultrasonic alarm module and alarm module for applying this method, especially in a motor vehicle - Google Patents

Description

The present invention relates to a method of setting of an alarm module, in particular a module alarm system, and an alarm module implements such a method, in particular in a vehicle automobile.

It finds its application in the field of protection against intrusion into a closed volume, such as a passenger compartment of a motor vehicle for example.

State alarm devices technique include transmitting means such as one or emission transducers for emitting waves, for example example of ultrasonic waves, in the volume at monitor. Depending on the size and shape of this volume, as well as those of objects that can possibly be there, a wave regime stationary is established within this volume.

The principle of intrusion detection in the volume to be monitored then consists in measuring the variations in the envelope level of the signal received on receiving means, such as one or more transducers reception.

Said receiving means are connected to a detection organ whose role is to detect these variations. Furthermore, it is necessary to previously amplify the received signal in order to make it exploitable by the detection device. This is why alarm devices have an amplifier arranged between the receiving means and the detection member.

In the alarm device using the method of the invention, the adjustment of the sensitivity of the alarm device is done by adjusting the gain of this amplifier.

In some known alarm devices, the setting is determined when sizing the device according to standard data such as by example the theoretical level of the ultrasonic waves emitted and the overall volume of the vehicle interior to protect.

One of the disadvantages of this type of adjustment lies in the fact that the level of the signal received on the receive transducer cannot be determined at advance because it is dependent on the steady state which is established in the passenger compartment of the vehicle. Indeed, according to whether the transducer is at a node or a belly standing waves, the level of the received signal is different.

In addition, the standing wave regime does not is not established completely frozen but is at otherwise a slowly variable stationary regime. This variation mainly depends on the conditions climates such as the temperature inside the vehicle, which depends in particular on climatic conditions very variable from one use to another. In the practical, it is estimated that the variation of the wave level received ultrasound which is induced by these different factors is in the range of one to twenty-five, the period of this variation can be of the order of a few minutes to several hours.

Furthermore, the major drawback of the type of setting described above is that the standing wave regime settling inside of the interior of a vehicle depends on different factors which are, on the one hand, the dispersion of characteristics of the transducers used both in transmission than reception, on the other hand, variations in volume of the passenger compartment due for example to the presence objects on the rear shelf or changes in the seating arrangement. In practice, it is believed that the variation in the level of ultrasonic waves received which is induced by these different factors is around one hundred.

We know that in the alarm modules of this type, uncontrolled variations in wave level received ultrasounds are often the cause of bad which can result in nuisance tripping of the alarm device, or by a non-triggering of the device despite a real intrusion inside the passenger compartment.

This is why, in other alarm modules of the state of the art, the gain of the amplifier device reception is automatically set to depending on the level of ultrasonic waves received by the reception transducer, see for example document EP 572 302 in which the sensitivity of an alarm system is adapted according to the average value of the reception signal and the maximum peak value of the output signal of the reception chain.

Each time the device is started, the standing wave regime conditions imposed by the specific arrangement of the space inside the passenger compartment of the vehicle are thus taken into account. Of more, the setting time being much less than the standing wave variation period slowly variable, this variation has no effect on the effectiveness of the alarm system.

However, variations in the wave level volume-induced ultrasound monitored, for example due to shock or intrusion, are independent of the wave state stationary. In particular, they are identical, that the receiving transducer is placed at a node standing waves, the gain of the amplifier reception then having a first determined value, or that it is placed in a belly of standing waves, the amplifier gain then having a second value determined greater than said first value.

Therefore, the sensitivity of the alarm device is not constant and depends on the same factors of variation than those mentioned above regarding the level of ultrasonic waves received by the transducer reception.

It is therefore impossible to base a setting of the gain of the reception amplifier on the level of ultrasonic waves received by the transducer reception.

The invention is defined by claims 1 to 10.

• une première phase dite phase d'émission, pendant laquelle un signal est émis par des moyens d'émission pendant un premier temps déterminé au bout duquel l'émission est coupée ;
• une seconde phase dite phase de réception, pendant laquelle des moyens de réception sont actifs pendant un deuxième temps déterminé ;
• une troisième phase, dite phase de mesure, pendant laquelle les niveaux maximum et minimum du signal d'enveloppe du signal ultrasonore reçu pendant un troisième temps déterminé, sont relevés et mémorisés,

   et en ce que la différence entre ledit niveau maximum et ledit niveau minimum dudit signal d'enveloppe, constitue un critère d'asservissement du gain d'un amplificateur d'entrée compris dans les moyens de réception du module d'alarme.In order to remedy the drawbacks of the aforementioned prior art, the present invention provides a new method for adjusting an alarm module, in particular an ultrasonic alarm module, in particular in a motor vehicle, characterized in that that an adjustment step includes:

• a first phase called the transmission phase, during which a signal is transmitted by transmission means during a first determined time after which the transmission is cut off;
• a second phase, called reception phase, during which reception means are active for a second determined time;
• a third phase, called the measurement phase, during which the maximum and minimum levels of the envelope signal of the ultrasonic signal received during a third predetermined time are noted and stored,

and in that the difference between said maximum level and said minimum level of said envelope signal constitutes a criterion for controlling the gain of an input amplifier included in the means for receiving the alarm module.

According to another characteristic of the invention, the measurement phase is broadly included in the reception phase.

According to another characteristic of the invention, the measurement phase begins after a fourth step determined elapsed since the start of the reception.

According to another characteristic of the invention, the measurement phase ends at the end of the measurement phase reception.

According to another characteristic of the invention, the adjustment step is provided at least during the setting in standby of the alarm module.

In addition, the present invention also relates to a alarm module implementing the adjustment method described above.

Indeed it also concerns an alarm module, such as an ultrasonic alarm module especially for the monitoring of a motor vehicle interior, type comprising a detection and control unit, transmission means, and wave reception means ultrasonic, characterized in that said means of reception include a variable gain amplifier the gain of which is adjusted according to the method described above.

According to another characteristic of the invention, the transmission means include a voltage generator periodical admitting an inhibition command, and means emitting ultrasonic waves such as at least one transmitter transducer like an ultrasonic cell operating in transmitter mode.

According to another characteristic of the invention the receiving means include receiving means such as at least one receiving transducer such as a ultrasonic cell operating in receiver mode, a variable gain amplifier, a demodulator ensuring amplitude demodulation of the received and amplified signal, as well as a low pass filter.

According to another characteristic of the invention, the variable gain amplifier of the receiving means has an adjustment input adapted to receive a signal to control its gain.

According to another characteristic of the invention, the detection and control unit consists of a integrated circuit such as a microcontroller or an asic.

• A la figure 1, une courbe représentant le niveau de l'enveloppe du signal ultrasonore reçu en fonction du temps pour une valeur déterminée de l'énergie moyenne présente dans l'habitacle du véhicule ;
• A la figure 2, une courbe représentant le niveau de l'enveloppe du signal ultrasonore reçu en fonction du temps pour deux valeurs déterminées distinctes de l'énergie moyenne présente dans l'habitacle du véhicule ;
• A la figure 3, une courbe représentant le niveau de l'enveloppe du signal ultrasonore reçu en fonction du temps lors de la mise sous alarme ;
• A la figure 4, une courbe représentant le niveau de l'enveloppe du signal ultrasonore reçu en fonction du temps lors des différentes phases de l'étape de réglage selon l'invention ;
• A la figure 5, un schéma de principe du module d'alarme mettant en oeuvre le procédé de réglage selon l'invention.

Other characteristics and advantages of the present invention will appear on reading the description and the accompanying drawings which are:

• In FIG. 1, a curve representing the level of the envelope of the ultrasonic signal received as a function of time for a determined value of the average energy present in the passenger compartment of the vehicle;
• In FIG. 2, a curve representing the level of the envelope of the ultrasonic signal received as a function of time for two determined values distinct from the average energy present in the passenger compartment of the vehicle;
• In FIG. 3, a curve representing the level of the envelope of the ultrasonic signal received as a function of time during the setting on alarm;
• In FIG. 4, a curve representing the level of the envelope of the ultrasonic signal received as a function of time during the different phases of the adjustment step according to the invention;
• In FIG. 5, a block diagram of the alarm module implementing the adjustment method according to the invention.

In Figure 1 and Figure 2, we can see curves to illustrate the problem of differences in sensitivity of the alarm module in function of the steady state which is established in the passenger compartment of the vehicle, in particular the presence of a standing wave knot or belly in the area of the space where the receiving means are placed of the alarm module and depending on the energy level average present in this cabin once the regime stationary establishes.

In these figures, the abscissa axis is the axis of time while the ordinate axis represents the envelope level values of the ultrasonic signal received.

In Figure 1, we consider an average energy present in the passenger compartment of the vehicle, say a level of emission of ultrasonic waves, climatic conditions and interior arrangement determined.

Under these conditions, the wave regime stationary is established in a determined manner. The signal received by the receiving means of the alarm module is processed by said means to extract its envelope. This envelope is in the form of a curve periodic 10 reflecting the alternation of nodes 11 and bellies 12 of the standing wave regime.

We note A the level of the envelope of the received signal by the receiving means of the alarm module when these are placed at a wave node stationary. the envelope level of the received signal by the receiving means of the alarm module when these are placed at a belly of waves stationary is around twenty-five times this level AT.

A variation in the volume of the passenger compartment, due to a phenomenon such as for example an intrusion into inside this volume, or a break-in by window, as well as a shock occurring against the vehicle and likely to modify the standing wave regime, produce a disturbance whose effect is a DELTA variation of the envelope level of the received signal by the means of reception of the alarm module.

This variation in DELTA level is represented in FIG. 1 by blocks 13 and 14. It is independent of the presence of a knot or belly standing waves in front of the reception means of the alarm module, which is translated in Figure 1 by identical height for blocks 13 and 14 which are located at node 11 and belly 12 respectively standing waves.

We therefore understand that if the sensitivity of the module alarm is set according to the level of the envelope of the signal received by its reception means, the same disturbance, resulting in the same variation DELTA of the level of this envelope, will be perceived as of different amplitude depending on the reception means of the alarm module are placed at a wave node stationary or that these are placed at a belly of standing waves. In fact it will be perceived as the case may be in the same report as the report of envelope levels of the received signal when the means the alarm module are located at a standing wave belly and when these get are placed at a standing wave node, say in a ratio of one to twenty five in the case shown in figure 1.

In Figure 2, we consider two situations different in which the average energy level in the passenger compartment of the vehicle respectively first determined value and a second value determined greater than said first value determined.

The first situation is represented by the curve 21 on which the signal envelope level ultrasonic received by the module receiving means alarm is equal to a first determined value.

The second situation is represented by the curve 22 on which the signal envelope level ultrasonic received by the module receiving means alarm is equal to a second determined value greater than said first value.

An identical disturbance in the volume of the passenger compartment, due to a phenomenon such as for example a intrusion into this volume, or a break-in by broken glass, as well as a shock occurring against the vehicle and likely to modify the wave regime steady, produces amplitude disturbance different depending on whether the operating conditions of the module correspond to said first situation or to said second situation.

In the first case, this disturbance occurs translated by a DELTA1 variation in the envelope level 21 of the signal received by the module reception means alarm.

In the second case, this disturbance is reflected by a DELTA2 variation in the level of the envelope 22 of the signal received by the module receiving means alarm, the value of this variation DELTA2 being greater than the value of the aforementioned DELTA1 variation. These DELTA1 and DELTA2 level variations are represented in FIG. 1 by blocks respectively 23 and 24.

The ratio of the values of the DELTA1 and DELTA2 is proportional to the ratio of the first determined value and the second determined value of average level of energy in the passenger compartment vehicle.

We therefore understand that in order to guarantee a constant detection sensitivity in all circumstances, a enslavement of the gain of the reception amplifier must take into account the average level of energy in the passenger compartment vehicle.

In an alarm device using the method adjustment according to the invention, such a control is executed.

When the driver of the automobile leaves his vehicle and places it under alarm, the alarm device enters a first phase or stage, called phase R of adjustment or adjustment step R, as shown in figure 3.

During this phase R, the transmitting means ultrasonic waves are controlled to emit acoustic waves in the passenger compartment of the vehicle.

Means for receiving ultrasonic waves then receive an ultrasonic signal whose envelope is represented by the curve in Figure 3.

The adjustment step is itself divided into several phases which are explained below in link with the description of Figure 4. In the practical, this phase lasts only a few seconds.

Once the adjustment phase R is completed, the alarm device enters a second phase, called monitoring phase S, which is the proper operation of the alarm device. During this phase S, the wave emitting means ultrasound emits continuously or intermittently, depending on whether the alarm device is continuous emission or works by alternating activations and deactivation of means emitting ultrasonic waves.

From the point of view of the signal envelope received ultrasound, adjustment phase R and phase S of monitoring start with a rise time tm corresponding to the establishment of the wave regime stationary inside the passenger compartment of the vehicle.

Once this regime is reached, the envelope level of the ultrasonic signal received by the reception means of ultrasonic waves is equal to an Enormal value, which depends on the steady state established in the area of the space where said reception means are located. This level remains constant at the disturbance scale produced by the phenomena to be detected such as a intrusion, shock, etc ...

In FIG. 4, the adjustment phase R is represented from an instant after the establishment of the standing wave regime.

In this figure we again consider the level envelope of the ultrasonic signal received according to the time.

Thus, during a first phase, called phase because it corresponds to a period during which the means for emitting ultrasonic waves are activated, the envelope level of the ultrasonic signal received is equal to Enormal. The portion of the curve corresponding is referenced 31 in FIG. 4.

The transmission phase ends after one first time determined Te. Waves emission means ultrasound is then deactivated and the device enters in a second phase called the reception phase.

During this phase, the wave regime stationary is broken and the acoustic energy present in the passenger compartment of the vehicle is no longer maintained, since the emission of ultrasonic waves is cut off. The envelope level of the ultrasonic signal received by the means of reception therefore evolves freely up to disappearance of this signal.

This development essentially depends on characteristics of monitored volume and level of energy present in the vehicle, such as when emission phase where the standing wave regime was established.

The reception phase itself includes a sub-phase, known as the measurement phase, which corresponds to a time interval Tm, included in the interval of time Tr that the reception phase lasts, during which the envelope level of the received ultrasonic signal is analyzed to extract the maximum value Emax and the minimum value Emin.

In a preferred embodiment of the invention, the measurement phase begins after a time determined To, for example equal to a few milliseconds after the start of the reception phase, i.e. also after deactivation of the transmission means of ultrasonic waves.

This time interval To is a time delay before the start of the measurement, which is intended to guarantee that said measurement is made under real conditions of break with respect to the standing wave regime prior.

In the preferred embodiment, the phase of measurement ends at the same time as the reception phase.

But we could consider variants of realization, for example a variant in which the measurement phase and reception phase would confused.

During the measurement phase, which spans a duration Tm for example of the order of a few tens of milliseconds, an adjustment and detection unit includes means to record and save the value maximum Emax and the minimum value Emin of the level of the envelope of the received ultrasonic signal.

The portion of curve 32 representing the evolution of this level during the measurement phase indeed includes a maximum point 33 and a corresponding minimum point 34 maximum Emax and minimum Emin level audits.

The maximum level Emax can be higher than Enormal level received during the transmission phase, because the Enormal level is dependent on the wave regime stationary established in the area of space where stands find the means for receiving ultrasonic waves and can correspond to any point of the Figure 2 curve.

The Emoy difference between the maximum level Emax and the minimum Emin level recorded during the measurement constitutes on the other hand a representative quantity of the average energy present in the passenger compartment of the vehicle. In particular, this quantity is independent of the steady state established during the phase resignation.

In addition, this quantity takes into account actual operating conditions of the device alarm on each standby, especially those that relate to the operating characteristics of means for transmitting and receiving ultrasonic waves, as well as the interior arrangements of the vehicle.

The size Emoy is therefore a usable size for adjusting the gain of the reception amplifier because it provides an adjustment criterion guaranteeing constant sensitivity in all circumstances.

In FIG. 5, a detection and command 40 is connected to reception means 42 by via a MES measurement input and a amplifier gain gain gain 47 said reception means 42. The detection unit and control is also connected to transmission means 41 by an INHIB output for inhibiting said means 41.

The transmission means 41 are constituted by a generator 43 of periodic electric voltage, by example of a sinusoidal voltage at a frequency by example equal to 40 kHz, and by transmitting means of ultrasonic waves 44, such as at least one transducer transmitter like an ultrasonic cell operating in transmission mode.

One of the terminals of the transmitter transducer 44 is connected to generator 43 while the other of its terminals is connected to the electrical ground of the circuit.

The transmitter transducer 44 is placed in the space to be monitored, such as the passenger compartment of a vehicle, and transforms electrical energy received from the acoustic energy generator 43 which is thus diffused inside the passenger compartment of the vehicle.

The generator 43 is adapted to receive a signal inhibition from the detection unit and command 41 whose effect is to cut the emission of acoustic energy in the passenger compartment of the vehicle.

This inhibition signal is in particular emitted by the detection and control unit during the whole duration Te of the reception phase described above.

• des moyens récepteurs d'ondes ultrasonores 46, tels qu'au moins un transducteur récepteur comme une celulle à ultrasons fonctionnant en mode réception ;
• un amplificateur 47 à gain variable ;
• un démodulateur d'amplitude 45 ;
• un multiplieur de tension 48 ;
• un filtre passe-bas 49.

The reception means 42 consist of the following elements placed in series:

• ultrasonic wave receiving means 46, such as at least one receiving transducer such as an ultrasonic cell operating in reception mode;
• a variable gain amplifier 47;
• an amplitude demodulator 45;
• a voltage multiplier 48;
• a low-pass filter 49.

Amplifier 47 is intended to amplify the signal received by the receiving means 46 in order to make it usable by the rest of the means of reception 42, in particular by the demodulator 45. In addition, the setting the gain of this amplifier allows you to control the sensitivity of the alarm device according to the the invention.

This is why amplifier 47 has a its gain control input which is adapted to receive a setpoint signal generated by the GAIN output of the detection and control unit 40.

The role of the whole constituted by the amplitude demodulator 45, the voltage multiplier 48, and through the low pass filter 49, is to extract the envelope signal of the ultrasonic signal received by the receiver transducer 46 and amplified by the amplifier variable gain 47, and make it usable by the detection and control unit 40. As such, the low-pass filter 49 removes residue from demodulation. In a preferred embodiment of the invention, the low pass filter is carried by the voltage multiplier 48. This is for example a multiplier by two, i.e. an amplifier whose the gain is equal to two, and includes a filtering stage low pass.

The envelope signal thus extracted is sent on the MES measurement input of the detection and setting.

The detection and control unit 40 comprises input means (not shown), such as a analog / digital converter, to acquire the envelope signal of the ultrasonic wave signal under an exploitable form for him.

Indeed, in a preferred embodiment of invention, the detection and control unit is constituted by a microcontroller controlled by a program internal.

Likewise, the gain control signal delivered by the GAIN output of the detection unit 40 and order is issued in the form of a train of fixed frequency rectangular pulses, the duty cycle is variable and carries the information of gain setting.

The gain control signal is transmitted under this shape at the REG setting input of the amplifier variable gain 47 which includes suitable means such than a low-pass filter (not shown) for the transform into analog information such as voltage, directly usable for gain control of the amplifier.

In practice, any type of amplifier variable gain is usable. In one embodiment possible from the invention the variable gain amplifier is controllable in voltage. Other types of order the amplifier are possible, for example a current control.

Claims (10)

1. A method of regulating an alarm module, in particular an ultrasonic alarm module, especially in a motor vehicle, characterised in that a regulating step comprises:

   a first phase, referred to as an emission phase, during which a signal is emitted by emitter means (41) during a first predetermined time period (Te), at the end of which the emission is cut;

   a second phase, referred to as a receiving phase, during which receiver means (42) are in operation during a second predetermined time period (Tr);

   a third phase, referred to as a measurement phase, during which the maximum level (Emax) and minimum level (Emin) of the envelope signal of the ultrasonic signal received during a third predetermined time period (Tm) are taken and memorised,

   and in that the difference (Ediff) between the said maximum level (Emax) and the said minimum level (Emin) of the said envelope signal constitutes a criterion for control of the gain of an input amplifier (47) which is included in the receiver means (42) of the alarm module.
2. A regulating method according to Claim 1, characterised in that the measurement phase is included in the receiving phase.
3. A regulating method according to Claim 2, characterised in that the measurement phase starts at the end of a fourth predetermined time period (To) running with effect from the start of the receiving phase.
4. A regulating method according to Claim 2 or Claim 3, characterised in that the measurement phase is terminated at the end of the receiving phase.
5. A regulating method according to any one of the preceding Claims, characterised in that the regulating step is arranged to take place at least during arming of the alarm module.
6. An alarm module, such as an ultrasonic alarm module, especially for surveillance of a motor vehicle cabin, of the type comprising a detection and control unit (40), emitter means (41), and receiver means (42), for waves such as ultrasonic waves, characterised in that the said receiver means (42) include a variable gain amplifier (47), the gain of which is regulated in accordance with the method of any one of the preceding Claims, and in which the difference (Ediff) between the maximum level (Emax) and the minimum level (Emin) of the envelope signal of the signal received therefore constitutes a criterion for control of the said signal.
7. An alarm module according to Claim 6, characterised in that the emitter means (41) include a generator (43) of periodic voltage admitting a command for inhibition, and ultrasonic wave emitting means such as at least one emitter transducer (44) such as an ultrasonic cell operating in emission mode.
8. An alarm module according to Claim 6, characterised in that the receiver means include receiving means such as a receiving transducer (46), for example an ultrasonic cell operating in receiving mode, a variable gain amplifier (47), a demodulator for amplitude demodulation of the received and amplified signal, and a low pass filter (49).
9. An alarm module according to Claim 6, characterised in that the variable gain amplifier (47) of the receiver means has a control input (REG) adapted to receive a signal for control of its gain.
10. An alarm module according to Claim 6, characterised in that the detection and control unit consists of an integrated circuit such as a microcontroller or an "asic".

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