DE102023203477A1 - OCCUPANCY DETECTION DEVICE AND METHOD FOR DETECTING THE OCCUPANCY STATE OF A VEHICLE COMPONENT - Google Patents

Abstract

The invention relates, inter alia, to an occupancy detection device (10) for detecting the occupancy state of a vehicle component. According to the invention, it is provided that the occupancy detection device (10) has an evaluation device (200) and at least one measuring module (100) connected to the evaluation device (200), the at least one measuring module (100) has a first electrode (110) which is connected to a first connection point (101) of the measuring module (100), is electrically insulated from a reference potential (BP) and forms a first electrical capacitance with the latter, the at least one measuring module (100) has a second electrode (120) which is connected to a second connection point (102) of the measuring module (100), is electrically insulated from the reference potential and forms a second electrical capacitance with the latter, the first and second electrodes are capacitively coupled by a coupling capacitance and the evaluation device (200) is designed to measure the first and second capacitances using at least three measuring steps (MS1-MS3) to form a first and second capacitance value (C1, C2), to calculate the quotient (C1/C2) between the capacitance values and to generate an occupancy signal (SB) if the quotient deviates from a predetermined target quotient (Qsoll) beyond a predetermined amount.

Description

The invention relates to occupancy detection devices which are suitable for detecting the occupancy state of a vehicle component.

Such occupancy detection devices are provided in motor vehicles, for example for steering wheels, in order to be able to check whether the driver of the motor vehicle is touching the steering wheel and is thus able to react to the traffic situation by steering movements.

Occupancy detection devices are also used in motor vehicles to detect the occupancy status of vehicle seats in order to recognize whether the vehicle seats are occupied by a passenger or not; the information about the occupancy can be used, for example, to generate a warning signal if a vehicle seat is recognized as being occupied by a passenger but the associated seat belt is not fastened. Other applications such as deactivating airbags when vehicle seats are unoccupied and the like are also known.

The invention is based on the object of specifying an occupancy detection device which is particularly durable and can provide trustworthy measurement results over a particularly long period of time.

This object is achieved according to the invention by an occupancy detection device with the features according to patent claim 1. Advantageous embodiments of the occupancy detection device according to the invention are specified in subclaims.

According to the invention, the occupancy detection device has an evaluation device and at least one measuring module connected to the evaluation device, the at least one measuring module has a first electrode which is connected to a first connection point of the measuring module, is electrically insulated from a reference potential and forms a first electrical capacitance with the latter, the at least one measuring module has a second electrode which is connected to a second connection point of the measuring module, is electrically insulated from the reference potential and forms a second electrical capacitance with the latter, the first and second electrodes are capacitively coupled by a coupling capacitance and the evaluation device is designed to determine the first and second capacitances by including at least three measuring steps to form a first and second capacitance value, to calculate the quotient between the capacitance values and to generate an occupancy signal if the quotient deviates from a predetermined target quotient by more than a predetermined amount.

A significant advantage of the occupancy detection device according to the invention is that it enables reliable occupancy detection over a particularly long period of time. This is because the quotient between the first and second capacitance values, i.e. a relative value and not an absolute value, is used as the measurement criterion for detecting the occupancy state. The invention is based on the idea that aging of the dielectric between the electrodes and the reference potential will change the two capacitance values used to form the quotient in a comparable manner; however, this change has no influence on the quotient between the capacitance values, since the dielectric constants cancel out when the quotient is formed and the quotient is therefore unaffected by the aging of the dielectric and the corresponding change in the dielectric constant. In contrast, the quotient is changed when a person approaches or occupies the vehicle component, since the occupancy will practically never or only negligibly rarely be so symmetrical that an approach to the two electrodes occurs in an identical manner and both capacitance values are changed in the same way; rather, there will always be an asymmetrical approach and thus a change in the quotient, which can be easily recognized by comparing the measured quotient with the target quotient according to the invention. The same applies to the aging of an insulating material that covers the electrodes on the outside.

Another significant advantage of the occupancy detection device according to the invention is that other external factors - such as temperature changes, changes in air humidity, moisture, electromagnetic radiation, especially sunlight - also have a symmetrical effect on the dielectric of the capacitances, so that the latter factors influence the absolute values of the capacitances, but not the quotient. The latter factors also do not influence the detection of the occupancy state.

It is advantageous if the evaluation device measures the capacitance between the first connection point and the reference potential as the first auxiliary capacitance measurement value in a first measuring step, if the second connection point is connected to the reference potential, the evaluation device measures the capacitance between the first connection point and the reference potential as a second auxiliary capacitance measurement value in a second measuring step when the second connection point is switched to a high-impedance tristate state, and the evaluation device measures the capacitance between the second connection point and the reference potential as a third auxiliary capacitance measurement value in a third measuring step when the first connection point is connected to the reference potential or switched to the high-impedance tristate state, wherein the order of the three measuring steps is arbitrary.

The evaluation device preferably comprises a measuring device for controlling the measuring steps, for determining the quotient and for forming the occupancy signal; such a measuring device is preferably formed by a microcontroller or preferably at least also comprises such a microcontroller.

It is considered particularly advantageous if the evaluation device measures the third auxiliary capacitance measurement value in the third measuring step after it has connected the first connection point to the reference potential.

und den zweiten Kapazitätswert vorzugsweise errechnen gemäß $$C2=Cm2-\sqrt{Cm3\cdot \left(Cm1-Cm2\right)}$$

wobei C1 den ersten Kapazitätswert, C2 den zweiten Kapazitätswert, Cm1 den ersten Hilfskapazitätsmesswert, Cm2 den zweiten Hilfskapazitätsmesswert und Cm3 den dritten Hilfskapazitätsmesswert bezeichnet.In the latter embodiment, the evaluation device will preferably calculate the first capacitance value according to $$\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="DE102023203477A1\_0024.png"\; state="\{\{state\}\}">C</figure-callout>}1=\mathrm{<figure-callout\; id="1"\; label="C\; m"\; filenames="DE102023203477A1\_0024.png"\; state="\{\{state\}\}">C</figure-callout>}m1-\sqrt{Cm3\cdot \left(\mathrm{<figure-callout\; id="1"\; label="C\; m"\; filenames="DE102023203477A1\_0024.png"\; state="\{\{state\}\}">C</figure-callout>}m1-Cm2\right)}$$

and preferably calculate the second capacitance value according to $$C2=Cm2-\sqrt{Cm3\cdot \left(\mathrm{<figure-callout\; id="1"\; label="C\; m"\; filenames="DE102023203477A1\_0024.png"\; state="\{\{state\}\}">C</figure-callout>}m1-Cm2\right)}$$

where C1 denotes the first capacitance value, C2 the second capacitance value, Cm1 the first auxiliary capacitance measurement value, Cm2 the second auxiliary capacitance measurement value and Cm3 the third auxiliary capacitance measurement value.

Preferably, the evaluation device calculates a coupling capacitance value C3 indicating the coupling capacitance according to: $$C3=\sqrt{Cm3\cdot \left(\mathrm{<figure-callout\; id="1"\; label="C\; m"\; filenames="DE102023203477A1\_0024.png"\; state="\{\{state\}\}">C</figure-callout>}m1-Cm2\right)}$$

With regard to a plausibility check, it is considered advantageous if the evaluation device switches the first connection point to the high-impedance tristate state in a fourth measuring step and measures the capacitance between the second connection point and the reference potential as a fourth auxiliary capacitance measurement value after it has switched the first connection point to the high-impedance tristate state.

The evaluation device then preferably subjects the fourth auxiliary capacitance measured value, the first capacitance value, the second capacitance value and the coupling capacitance value to a plausibility check.

In the latter embodiment, it is considered advantageous if the evaluation device checks, as part of the plausibility check, whether the fourth auxiliary capacity measurement value deviates from a target capacity measurement value beyond a predetermined capacity deviation measure.

The evaluation device calculates the target capacity measured value preferably according to $$Cs4=\sqrt{\frac{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="DE102023203477A1\_0024.png"\; state="\{\{state\}\}">C</figure-callout>}1\cdot C2+\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="DE102023203477A1\_0024.png"\; state="\{\{state\}\}">C</figure-callout>}1\cdot C3+C2\cdot C3}{C2+C3}}$$

In a preferred measurement embodiment, it is provided that the evaluation device applies a measuring pulse to the first connection point via a first series resistor in the first and/or second measuring step and determines the first and second auxiliary capacitance measurement values by evaluating the temporal progression of the voltage applied to the first connection point.

In the third and/or fourth measuring step, the evaluation device applies a measuring pulse to the second connection point, preferably via a second series resistor, and determines the third and/or fourth auxiliary capacitance measurement value by evaluating the temporal progression of the voltage applied to the second connection point.

Alternatively or additionally, it can be advantageously provided that the evaluation device in the first and/or second measuring step feeds an alternating current into the first connection point or applies an alternating voltage to the first connection point and determines the first and/or second auxiliary capacitance measurement value by evaluating the alternating voltage present at the first connection point or the alternating current flowing at the first connection point.

Alternatively or additionally, it can be advantageously provided that the evaluation device in the third and/or fourth measuring step feeds an alternating current into the second connection point or applies an alternating voltage to the second connection point and determines the third and/or fourth auxiliary capacitance measurement value by evaluating the alternating voltage present at the second connection point or the alternating current flowing at the second connection point.

One of the two electrodes or both electrodes can also be used for heating. Such heating operation can be combined with the measuring operation for recording the occupancy status within the framework of a time-multiplex operation.

Accordingly, it is considered advantageous if the first electrode is connected with a first electrode end to the first connection point of the measuring module and with a second electrode end to a heating connection point of the measuring module and a heating operation switching device is present which enables an application of a vehicle-side on-board voltage between the first connection point and the heating connection point of the measuring module and an operation of the first electrode as a heating element.

It is advantageous if a disconnector is connected between the measuring device of the occupancy detection device and the first connection point. When open, the disconnector disconnects the first connection point from the measuring device and, when closed, connects the first connection point to the measuring device. The closed state of the disconnector is preferably only set when the heating operation switching device has electrically disconnected the on-board voltage from the measuring module.

In a preferred embodiment, the occupancy detection device is a steering wheel touch detection device and the measuring module is designed for integration into a vehicle steering wheel.

In another preferred embodiment, the occupancy detection device is a seat occupancy detection device and the measuring module is designed for integration into a vehicle seat.

The invention also relates to a steering wheel for a vehicle. According to the invention, the steering wheel is equipped with a measuring module of an occupancy detection device as described above.

The invention also relates to a vehicle seat for a vehicle. According to the invention, the vehicle seat is equipped with a measuring module of an occupancy detection device as described above.

The invention also relates to a method for detecting the occupancy state of a vehicle component. According to the invention, the method provides that the occupancy state is detected using at least one measuring module, the at least one measuring module has a first electrode that is connected to a first connection point of the measuring module, is electrically insulated from a reference potential and forms a first electrical capacitance thereto, the at least one measuring module has a second electrode that is connected to a second connection point of the measuring module, is electrically insulated from the reference potential and forms a second electrical capacitance thereto, the first and second electrodes are capacitively coupled by a coupling capacitance and, using at least three measuring steps, the first and second capacitances are determined to form a first and second capacitance value, the quotient between the capacitance values is calculated and an occupancy signal is generated if the quotient deviates from a predetermined target quotient by more than a predetermined amount.

With regard to the advantages of the method according to the invention and its advantageous embodiments, reference is made to the above statements in connection with the occupancy detection device according to the invention and its advantageous embodiments.

• 1 ein Ausführungsbeispiel für eine erfindungsgemäße Belegungserfassungseinrichtung, wobei eine bevorzugte Ausgestaltung eines Messmoduls der Belegungserfassungseinrichtung näher im Detail dargestellt ist,
• 2 näher im Detail eine bevorzugte Ausgestaltung einer Auswerteinrichtung, die beispielsweise für die Belegungserfassungseinrichtung gemäß 1 geeignet ist,
• 3 ein Ausführungsbeispiel für eine bevorzugte Arbeitsweise der Auswerteinrichtung gemäß 2 in Form eines Flussdiagramms,
• 4 ein weiteres Ausführungsbeispiel für eine bevorzugte Arbeitsweise der Auswerteinrichtung gemäß 2 in Form eines Flussdiagramms,
• 5 ein Ausführungsbeispiel für eine erfindungsgemäße Belegungserfassungseinrichtung, die mit einer Heizfunktion ausgestattet ist,
• 6 eine bevorzugte Ausgestaltung eines in der 5 gezeigten Trennschalters näher im Detail,
• 7 einen Messverlauf bei Anlegen eines Spannungspulses an das Messmodul,
• 8 ein Ausführungsbeispiel für eine Anordnung mit einem Lenkrad, in das ein Messmodul eines Ausführungsbeispiels für eine erfindungsgemäße Belegungserfassungseinrichtung integriert ist,
• 9 ein Ausführungsbeispiel für eine Anordnung mit einem Fahrzeugsitz, in den ein Messmodul eines Ausführungsbeispiels für eine erfindungsgemäße Belegungserfassungseinrichtung integriert ist, und
• 10-13 die Schaltzustände während der verschiedenen Messschritte.

The invention is explained in more detail below using exemplary embodiments, which show, for example:

• 1 an embodiment of an occupancy detection device according to the invention, wherein a preferred embodiment of a measuring module of the occupancy detection device is shown in more detail,
• 2 in more detail a preferred embodiment of an evaluation device, which for example for the occupancy detection device according to 1 is suitable,
• 3 an embodiment of a preferred mode of operation of the evaluation device according to 2 in the form of a flow chart,
• 4 another embodiment of a preferred mode of operation of the evaluation device according to 2 in the form of a flow chart,
• 5 an embodiment of an occupancy detection device according to the invention, which is equipped with a heating function,
• 6 a preferred embodiment of a 5 shown isolating switch in more detail,
• 7 a measurement curve when a voltage pulse is applied to the measuring module,
• 8 an embodiment of an arrangement with a steering wheel in which a measuring module an embodiment of an occupancy detection device according to the invention,
• 9 an embodiment of an arrangement with a vehicle seat in which a measuring module of an embodiment of an occupancy detection device according to the invention is integrated, and
• 10-13 the switching states during the different measuring steps.

For the sake of clarity, the same reference symbols are always used in the figures for identical or comparable components.

The 1 shows an embodiment of an occupancy detection device 10 according to the invention, which is used to detect the occupancy state of a 1 vehicle component not shown. The occupancy detection device 10 according to 1 comprises a measuring module 100 and an evaluation device 200 connected to it.

A first electrode end 111 of a first electrode 110 of the measuring module 100 is connected to a first connection point 101 of the measuring module 100. The first electrode 110 is electrically insulated from a reference potential BP, which can be, for example, the ground potential of a vehicle or the earth potential, and forms with it a first electrical capacitance which has a first capacitance value C1.

The second electrode end 112 of the first electrode 110 is not connected to any connection point of the measuring module 100 or is not electrically connected; for the sake of better understanding, it should already be mentioned that this is the case in the embodiment according to 5 is different because there the second electrode end 112 is connected to a heating connection point 103 of the measuring module 100, as will be explained in more detail below.

A first electrode end 121 of a second electrode 120 of the measuring module 100 is connected to a second connection point 102 of the measuring module 100. The second electrode 120 is also electrically insulated from the reference potential BP and forms with it a second electrical capacitance which has a second capacitance value C2. The second electrode end 112 of the second electrode 120 is also not connected to any connection point of the measuring module 100 or is also not electrically connected.

The first and second electrodes 110 and 120 are arranged close to one another so that they are electrically capacitively coupled to one another and together form a coupling capacitance having a coupling capacitance value C3.

The first and second electrodes 110 and 120 are preferably insulated from the reference potential BP using the same dielectric, so that changes in the dielectric constant caused, for example, by environmental influences (temperature changes, moisture, changes in air humidity, electromagnetic radiation, etc.) or aging will affect both capacitance values C1 and C2 in - at least approximately - an identical manner; in concrete terms, this means that environmental influences or aging will not cause any change, at least approximately no relevant change, in the ratio C1/C2 between the first capacitance value C1 and the second capacitance value C2.

The evaluation device 200 is designed to determine the first and second capacitances by forming the first and second capacitance values C1 and C2, taking into account at least three measuring steps, to calculate the quotient C1/C2 between the capacitance values and to generate an occupancy signal SB if the quotient C1/C2 deviates from a predetermined target quotient Qsoll beyond a predetermined amount, but preferably only under the condition that the measurement results are plausible.

The 2 shows a preferred embodiment of the evaluation device 200 of the occupancy detection device 10 according to 1 in more detail. The evaluation device 200 includes, among other things, a computing device 211 and a memory 212 in which a computer program product CPP and the aforementioned target quotient Qsoll are stored in a non-volatile manner. If the computing device 211 executes the computer program product CPP, the computer program product determines the mode of operation of the evaluation device 200 or at least helps determine the mode of operation.

The evaluation device 200 also comprises a plurality of transistors, of which 3 eight and are identified by the reference symbols T1 to T8. The transistors T1 to T8 can each be controlled by the computing device 211 via control lines not shown.

The evaluation device 200 also comprises two AD converters AD1 and AD2, which can be read out by the computing device 211 via readout lines, also not shown.

The computing device 211, the memory 212, the transistors T1 to T8 and the two AD Converters AD1 and AD2 are in the embodiment according to 2 Components of a measuring device, which is preferably designed as a microcontroller 210.

A first connection port P1 of the microcontroller 210 is directly connected to the first connection point 101 of the measuring module 100. A second connection port P2 of the microcontroller 210 is indirectly connected to the first connection point 101 of the measuring module 100 via a first series resistor R1.

A third connection port P3 of the microcontroller 210 is directly connected to the second connection point 102 of the measuring module 100. A fourth connection port P4 of the microcontroller 210 is indirectly connected to the second connection point 102 of the measuring module 100 via a second series resistor R2.

By switching the transistors T1 to T8 on and off, the microcontroller 210 or its computing device 211 can optionally connect the connection points 101 and 102 to the reference potential BP, put them into a high-impedance tristate state or apply a measurement signal to them; the transistors T1 to T8 thus enable the microcontroller 210 or its computing device 211 to carry out a large number of different measurement steps one after the other.

The 3 shows in the form of a flow chart a preferred embodiment of the operation of the microcontroller 210 and thus implicitly also a preferred embodiment of the computer program product CPP according to 2 , in the event that the microcontroller 210 is to check whether a vehicle component is occupied or not.

In a first measuring step MS1, the microcontroller 210 measures the capacitance between the first connection point 101 and the reference potential BP as the first auxiliary capacitance measurement value Cm1 after it has connected the second connection point 102 to the reference potential BP. The 10 shows the corresponding switching state.

In a second measuring step MS2, the microcontroller 210 measures the capacitance between the first connection point 101 and the reference potential BP as the second auxiliary capacitance measurement value Cm2 after it has switched the second connection point 102 to a high-resistance tristate state. 11 shows the corresponding switching state.

In a third measuring step MS3, the microcontroller 210 measures the capacitance between the second connection point 102 and the reference potential BP as the third auxiliary capacitance measurement value Cm3 after it has connected the first connection point 101 to the reference potential BP. The 12 shows the corresponding switching state.

The order of the three measuring steps MS1 to MS3 is arbitrary.

und den zweiten Kapazitätswert C2 gemäß $$C2=Cm2-\sqrt{Cm3\cdot \left(Cm1-Cm2\right)}$$

wobei C1 den ersten Kapazitätswert, C2 den zweiten Kapazitätswert, Cm1 den ersten Hilfskapazitätsmesswert, Cm2 den zweiten Hilfskapazitätsmesswert und Cm3 den dritten Hilfskapazitätsmesswert bezeichnet.In a calculation step RS, the microcontroller 210 determines the first capacitance value C1 according to $$\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="DE102023203477A1\_0024.png"\; state="\{\{state\}\}">C</figure-callout>}1=\mathrm{<figure-callout\; id="1"\; label="C\; m"\; filenames="DE102023203477A1\_0024.png"\; state="\{\{state\}\}">C</figure-callout>}m1-\sqrt{Cm3\cdot \left(\mathrm{<figure-callout\; id="1"\; label="C\; m"\; filenames="DE102023203477A1\_0024.png"\; state="\{\{state\}\}">C</figure-callout>}m1-Cm2\right)}$$

and the second capacitance value C2 according to $$C2=Cm2-\sqrt{Cm3\cdot \left(\mathrm{<figure-callout\; id="1"\; label="C\; m"\; filenames="DE102023203477A1\_0024.png"\; state="\{\{state\}\}">C</figure-callout>}m1-Cm2\right)}$$

where C1 denotes the first capacitance value, C2 the second capacitance value, Cm1 the first auxiliary capacitance measurement value, Cm2 the second auxiliary capacitance measurement value and Cm3 the third auxiliary capacitance measurement value.

In an occupancy test step BPS, the microcontroller 210 checks whether the quotient C1/C2 between the first capacitance value C1 and the second capacitance value C2 deviates from the specified target quotient Qsoll beyond a specified amount MAX and generates corresponding output signals, for example according to

|C1/C2 - Osoll| > MAX ⇒ Generation of the occupancy signal SB, which indicates an occupied state of the vehicle component, and
|C1/C2) - Osoll| < MAX ⇒ Generation of a free signal FS, which can also be referred to as an unoccupied signal and indicates an unoccupied state of the vehicle component.

The 4 shows in the form of a further flow chart a preferred development of the embodiment according to 3 .

In further training according to 4 the microcontroller 210 also carries out a fourth measuring step MS4, in which it measures the capacitance between the second connection point 102 and the reference potential BP as the fourth auxiliary capacitance measurement value Cm4 after it has switched the first connection point 101 to the high-resistance tristate state. The 13 shows the corresponding switching state.

In addition, the microcontroller 210 calculates the coupling capacitance value C3 in the calculation step RS according to $$C3=\sqrt{Cm3\cdot \left(\mathrm{<figure-callout\; id="1"\; label="C\; m"\; filenames="DE102023203477A1\_0024.png"\; state="\{\{state\}\}">C</figure-callout>}m1-Cm2\right)}$$

The microcontroller 210 then checks in a plausibility check step PPS whether the fourth auxiliary capacitance measurement value Cm4 corresponds to a target capacitance measurement value Cs4 or deviates too much from it. The target capacitance measurement value Cs4 is preferably calculated as follows: $$Cs4=\sqrt{\frac{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="DE102023203477A1\_0024.png"\; state="\{\{state\}\}">C</figure-callout>}1\cdot C2+\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="DE102023203477A1\_0024.png"\; state="\{\{state\}\}">C</figure-callout>}1\cdot C3+C2\cdot C3}{C2+C3}}$$

If the amount of the difference between the fourth auxiliary capacity measurement value Cm4 and the target capacity measurement value Cs4 falls below a specified deviation limit CMAX, the measurement result is plausible and a plausibility signal PS is output; otherwise a warning signal WS is output, which warns of a lack of plausibility and preferably blocks the output of the occupancy signal SB, for example according to
|Cm4 - Cs4| < CMAX ⇒ Generation of a plausibility signal PS
|Cm4 - Cs4| > CMAX ⇒ Generation of a warning signal WS and blocking of an output of the occupancy signal SB.

The 5 shows a further embodiment of an occupancy detection device 10 according to the invention, which is suitable for detecting the occupancy state of a vehicle component.

In the occupancy detection device 10 according to 5 the first electrode 110 is connected with the first electrode end 111 to the first connection point 101 and with the second electrode end 112 (cf. 1 ) to a heating connection point 103 of the measuring module 100.

A heating operation switching device 220 is connected between the microcontroller 210 and the electrode 110 of the measuring module 100, which enables an on-board voltage Ub to be applied between the first connection point 101 and the heating connection point 103 of the measuring module 100 and enables the first electrode 110 to be operated as a heating element. For this purpose, the heating operation switching device 220 has a first switching device 221 between the on-board voltage Ub and the first connection point 101 and a second switching device 222 between the heating connection point 103 and the reference potential BP.

In order to protect the connection ports P1 and P2 of the microcontroller 210 from the on-board voltage Ub, a disconnector 223 is connected between the connection ports P1 and P2 and the first switching device 221 of the heating operation switching device 220. When opened, the disconnector 223 disconnects the first connection point 101 from the microcontroller 210 and, when closed, connects the first connection point 101 to the microcontroller 210. The disconnector 223 thus enables heating operation as an alternative to measuring operation or occupancy testing; the heating operation and the measuring operation are preferably carried out one after the other using a time-division multiplexing method.

The first switching device 221, the second switching device 222 and the isolating switch 223 are preferably controlled by the microcontroller 210 via connection ports (not shown) and control lines (not shown).

Of course, a heating connection point and a heating operation switching device can also be provided for the second electrode 120 if the second electrode 120 is to be used for heating.

The 6 shows a preferred embodiment of the 5 shown disconnector 223 in more detail.

In the cases mentioned above in connection with the 1 to 6 In the embodiments described, it can advantageously be provided that the microcontroller 210 carries out the first measuring step MS1 and the second measuring step MS2 by applying a measuring pulse to the first connection point 101 via the first series resistor R1 and determining the first and second auxiliary capacitance measured values Cm1 and Cm2 by evaluating the temporal progression of the voltage applied to the first connection point 101.

In the third measuring step MS3, the microcontroller 210 applies a measuring pulse to the second connection point 102, preferably via the second series resistor R2, and determines the third auxiliary capacitance measurement value Cm3 by evaluating the temporal progression of the voltage applied to the second connection point 102.

The 7 shows, by way of example, the increase in the voltage applied to the first connection point 101 and thus to the first connection port P1 in the event of an output of a rectangular voltage pulse at the second connection port P2.

Examples include the 7 The curves for two different load capacitances of 300pF and 350pF each are shown to visualize the difference in the measured value curve.

wobei Uc die Spannung an dem ersten Anschlussport P1, U0 die Amplitude des Spannungspulses am zweiten Anschlussport P2 und C die gesuchte Lastkapazität an der ersten Anschlussstelle 101 bezeichnet, die den Hilfskapazitätsmesswert Cm1 oder Cm2 je nach Beschaltung des dritten und vierten Anschlussports P3 und P4 aufweist.Preferably, a sampling time ta in the “linear” range of the exponential increase of the voltage curve is selected for evaluation. The determination of the load capacity from the measured voltage is preferably carried out according to the following basic formula: $$Uc\left(t\right)=U0\left(1-e^{-\frac{t}{R_{1}C}}\right)$$

where Uc is the voltage at the first connection port P1, U0 is the amplitude of the voltage pulse at the second connection port P2 and C is the required load capacitance at the first connection point 101, which has the auxiliary capacitance measurement value Cm1 or Cm2 depending on the wiring of the third and fourth connection ports P3 and P4.

Setzt man einen Einzelmesspuls beispielsweise mit ca. 500µs an, so ist man in der Lage, die oben erläuterten vier Messschritte MS1 bis MS4 eines Zyklus in 2ms zu erledigen.The required capacity C is $$C=-\frac{ta}{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="DE102023203477A1\_0024.png"\; state="\{\{state\}\}">R</figure-callout>}1*ln\left(1-\frac{Uc\left(ta\right)}{U0}\right)}$$

If you set a single measuring pulse of about 500µs, for example, you can complete the four measuring steps MS1 to MS4 of a cycle explained above in 2ms.

Of course, it makes sense to record a large number of pulses in order to average the result and minimize possible interference. A fast response in the range of less than 100ms is therefore achievable in practice.

Alternatively or additionally, in the first and/or second measuring step MS1 and MS2, the microcontroller 210 can feed an alternating current into the first connection point 101 or apply an alternating voltage to the first connection point 101 and determine the first and/or second auxiliary capacitance measurement value Cm1 and Cm2 by evaluating the alternating voltage present at the first connection point 101 or the alternating current flowing at the first connection point 101, for example by evaluating the magnitude and phase or the in-phase and quadrature components.

Alternatively or additionally, in the third and/or fourth measuring step MS3 or MS4, the microcontroller 210 can feed an alternating current into the second connection point 102 or apply an alternating voltage to the second connection point 102 and determine the third and/or fourth auxiliary capacitance measurement value Cm3 or Cm4 by evaluating the alternating voltage present at the second connection point 102 or the alternating current flowing at the second connection point 102, for example by evaluating the magnitude and phase or the in-phase and quadrature components.

The 8 shows an occupancy detection device 10 in the form of a steering wheel contact detection device, in which the measuring module 100 is integrated into a vehicle steering wheel 500. The electrodes of the measuring module 100 are preferably separated from the steering wheel skeleton, which is at the reference potential, by foam or the like. The evaluation device 200 is preferably spatially separated from the measuring module 100 and the steering wheel 500 and is located, for example, in a separate control unit of the vehicle.

The 9 shows an occupancy detection device 10 in the form of a seat occupancy detection device, in which the measuring module 100 is integrated in a seat surface of a vehicle seat 600. The electrodes of the measuring module 100 are preferably separated by insulating material from a seat frame that is at the reference potential. The evaluation device 200 is preferably spatially separated from the measuring module 100 and the vehicle seat 600 and is located, for example, in a separate control unit of the vehicle.

In the embodiments according to the 1 to 9 For example, only one measuring module 100 is connected to the evaluation device 200 or the microcontroller 210; of course, more than one measuring module 100 can be connected to the evaluation device 200 or the microcontroller 210 if the evaluation device 200 or the microcontroller 210 is equipped with a correspondingly larger number of connection ports.

Finally, it should be mentioned that the features of all embodiments described above can be combined with each other in any way to form further other embodiments of the invention.

All features of subclaims can also be combined with each of the subordinate claims, either individually or in any combination with one or more other subclaims, in order to obtain further other embodiments.

list of reference symbols

10

occupancy recording device

100

measuring module

101

first junction

102

second junction

103

heating connection point

110

first electrode

111

first electrode end

112

second electrode end

120

second electrode

121

first electrode end

122

second electrode end

200

evaluation device

210

microcontroller

211

computing device

212

memory

220

heating operation switching device

221

first switching device

222

second switching device

223

circuit breaker

500

vehicle steering wheel

600

vehicle seat

AD1

AD converter

AD2

AD converter

BP

reference potential

BPS

occupancy check step

C1

first capacity value

C1/C2

quotient

C2

second capacity value

C3

coupling capacitance value

Cm1-Cm4

auxiliary capacity measurements

CPP

computer program product

Cs4

target capacity measurement value

FS

free signal

MS1-MS4

measurement steps

P1-P4

connection ports

PPS

plausibility check step

PS

plausibility signal

Qsoll

target ratio

R1

first series resistor

R2

second series resistor

RS

calculation step

SB

occupancy signal

ta

sampling time

T1-T8

transistors

Ub

on-board voltage

WS

warning signal

Claims (14)

Occupancy detection device (10) for detecting the occupancy state of a vehicle component, characterized in that - the occupancy detection device (10) has an evaluation device (200) and at least one measuring module (100) connected to the evaluation device (200), - the at least one measuring module (100) has a first electrode (110) which is connected to a first connection point (101) of the measuring module (100), is electrically insulated from a reference potential (BP) and forms a first electrical capacitance with the latter, - the at least one measuring module (100) has a second electrode (120) which is connected to a second connection point (102) of the measuring module (100), is electrically insulated from the reference potential and forms a second electrical capacitance with the latter, - the first and second electrodes are capacitively coupled by a coupling capacitance and - the evaluation device (200) is designed to include at least three measuring steps (MS1-MS3) to determine the first and second capacitances by forming a first and second capacitance value (C1, C2), to calculate the quotient (C1/C2) between the capacitance values and to generate an occupancy signal (SB) if the quotient deviates from a predetermined target quotient (Qsoll) beyond a predetermined amount. Occupancy detection device (10) according to claim 1 , characterized in that - the evaluation device (200) measures the capacitance between the first connection point and the reference potential as the first auxiliary capacitance measurement value (Cm1) in a first measuring step (MS1) when the second connection point is connected to the reference potential, - the evaluation device (200) measures the capacitance between the first connection point and the reference potential as the second auxiliary capacitance measurement value (Cm2) in a second measuring step (SM2) when the second connection point is switched to a high-impedance tristate state, and - the evaluation device (200) measures the capacitance between the second connection point and the reference potential as the third auxiliary capacitance measurement value (Cm3) in a third measuring step (MS3) when the first connection point is connected to the reference potential or switched to the high-impedance tristate state, - the order of the three measuring steps is arbitrary. Occupancy detection device (10) according to claim 2 , characterized in that the evaluation device (200) - in the third measuring step, connects the first connection point to the reference potential and measures the third auxiliary capacitance measurement value after having connected the first connection point to the reference potential, - calculates the first capacitance value according to $$C1=Cm1-\sqrt{Cm3\cdot \left(Cm1-Cm2\right)}$$

and - the second capacity value calculated according to $$C2=Cm2-\sqrt{Cm3\cdot \left(Cm1-Cm2\right)}$$

- where C1 denotes the first capacitance value, C2 the second capacitance value, Cm1 the first auxiliary capacitance measurement value, Cm2 the second auxiliary capacitance measurement value and Cm3 the third auxiliary capacitance measurement value. Occupancy detection device (10) according to claim 3 , characterized in that the evaluation device (200) - in a fourth measuring step (MS4) switches the first connection point to the high-resistance tristate state and measures the capacitance between the second connection point and the reference potential as a fourth auxiliary capacitance measurement value (Cm4) after it has switched the first connection point to the high-resistance tristate state, - calculates a coupling capacitance value indicating the coupling capacitance according to $$C3=\sqrt{Cm3\cdot \left(Cm1-Cm2\right)}$$

where C3 denotes the coupling capacitance value, and - subjects the fourth auxiliary capacitance measured value, the first capacitance value, the second capacitance value and the coupling capacitance value to a plausibility check. Occupancy detection device (10) according to claim 4 , characterized in that the evaluation device (200) checks, as part of the plausibility check, whether the fourth auxiliary capacity measurement value deviates from a target capacity measurement value (Cs4) beyond a predetermined capacity deviation measure, wherein the evaluation device (200) calculates the target capacity measurement value Cs4 according to $$Cs4=\sqrt{\frac{C1\cdot C2+C1\cdot C3+C2\cdot C3}{C2+C3}}$$

Occupancy detection device (10) according to one of the preceding claims, characterized in that - in the first and second measuring steps, the evaluation device (200) applies a measuring pulse to the first connection point via a first series resistor (R1) and determines the first and second auxiliary capacitance measured value by evaluating the temporal progression of the voltage applied to the first connection point and - in the third measuring step, the evaluation device (200) applies a measuring pulse to the second connection point via a second series resistor (R2) and determines the third auxiliary capacitance measured value by evaluating the temporal progression of the voltage applied to the second connection point. Occupancy detection device (10) according to one of the preceding claims, characterized in that - in the first and second measuring steps, the evaluation device (200) feeds an alternating current into the first connection point or applies an alternating voltage to the first connection point and determines the first and second auxiliary capacitance measured value by evaluating the alternating voltage present at the first connection point or the alternating current flowing at the first connection point and - in the third measuring step, the evaluation device (200) feeds an alternating current into the second connection point or applies an alternating voltage to the second connection point and determines the third auxiliary capacitance measured value by evaluating the alternating voltage present at the second connection point or the alternating current flowing at the second connection point. Occupancy detection device (10) according to one of the preceding claims, characterized in that - the first electrode is connected with a first electrode end (111) to the first connection point of the measuring module (100) and with a second electrode end (112) to a heating connection point (103) of the measuring module (100) and - a heating operation switching device (200) is present which enables an on-board voltage (Ub) to be applied between the first connection point and the heating connection point of the measuring module (100) and an operation of the first electrode as a heating element. Occupancy detection device (10) according to claim 8 , characterized in that - a isolating switch (223) is connected between a measuring device (210) of the occupancy detection device (10) and a first switching device (221) of the heating operation switching device and - the isolating switch, in the open state, separates the first connection point and the first switching device (221) of the heating operation switching device from the measuring device and, in the closed state, the first connection point and the first Switching device (221) with the measuring device. Occupancy detection device (10) according to one of the preceding claims, characterized in that the occupancy detection device (10) is a steering wheel touch detection device and the measuring module (100) is designed for integration into a vehicle steering wheel (500). Occupancy detection device (10) according to one of the preceding Claims 1 until 9 , characterized in that the occupancy detection device (10) is a seat occupancy detection device and the measuring module (100) is designed for integration into a vehicle seat (600). Steering wheel for a vehicle, characterized in that the steering wheel (500) is provided with a measuring module (100) of an occupancy detection device (10) according to claim 10 is equipped. Vehicle seat, characterized in that the vehicle seat (600) is provided with a measuring module (100) of an occupancy detection device (10) according to claim 11 is equipped. Method for detecting the occupancy state of a vehicle component, characterized in that - the occupancy state is detected using at least one measuring module (100), - the at least one measuring module (100) has a first electrode which is connected to a first connection point of the measuring module (100), is electrically insulated from a reference potential and forms a first electrical capacitance thereto, - the at least one measuring module (100) has a second electrode which is connected to a second connection point of the measuring module (100), is electrically insulated from the reference potential and forms a second electrical capacitance thereto, - the first and second electrodes are capacitively coupled by a coupling capacitance and - the first and second capacitances are determined using at least three measuring steps to form a first and second capacitance value, the quotient between the capacitance values is calculated and an occupancy signal is generated if the quotient deviates from a predetermined target quotient by more than a predetermined amount.

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