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EP4594159A1 - Method for sensing the presence of a human hand in a gripping region of a steering wheel - Google Patents

Method for sensing the presence of a human hand in a gripping region of a steering wheel

Info

Publication number
EP4594159A1
EP4594159A1 EP23777247.0A EP23777247A EP4594159A1 EP 4594159 A1 EP4594159 A1 EP 4594159A1 EP 23777247 A EP23777247 A EP 23777247A EP 4594159 A1 EP4594159 A1 EP 4594159A1
Authority
EP
European Patent Office
Prior art keywords
steering wheel
sensor
wheel core
input
core
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP23777247.0A
Other languages
German (de)
French (fr)
Inventor
Christian Brüggemann
Matthias Seifert
Tobias HEINLOTH
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Kostal Automobil Elektrik GmbH and Co KG
Original Assignee
Kostal Automobil Elektrik GmbH and Co KG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kostal Automobil Elektrik GmbH and Co KG filed Critical Kostal Automobil Elektrik GmbH and Co KG
Publication of EP4594159A1 publication Critical patent/EP4594159A1/en
Pending legal-status Critical Current

Links

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B62LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62DMOTOR VEHICLES; TRAILERS
    • B62D1/00Steering controls, i.e. means for initiating a change of direction of the vehicle
    • B62D1/02Steering controls, i.e. means for initiating a change of direction of the vehicle vehicle-mounted
    • B62D1/04Hand wheels
    • B62D1/046Adaptations on rotatable parts of the steering wheel for accommodation of switches
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01DMEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/14Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
    • G01D5/24Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying capacitance
    • HELECTRICITY
    • H03ELECTRONIC CIRCUITRY
    • H03KPULSE TECHNIQUE
    • H03K17/00Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/94Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the way in which the control signals are generated
    • H03K17/945Proximity switches
    • H03K17/955Proximity switches using a capacitive detector
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B62LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62DMOTOR VEHICLES; TRAILERS
    • B62D1/00Steering controls, i.e. means for initiating a change of direction of the vehicle
    • B62D1/02Steering controls, i.e. means for initiating a change of direction of the vehicle vehicle-mounted
    • B62D1/04Hand wheels
    • B62D1/06Rims, e.g. with heating means; Rim covers

Definitions

  • the invention relates to a method for detecting the presence of a human hand in a gripping area of a steering wheel by means of a capacitive sensor system, wherein the presence of a human hand in a detection area of a sensor structure comprising at least one sensor electrode connected to a first input/output of a sensor electronics represents a change in a capacitive coupling of the sensor electrode with a reference potential relative to a reference state without the presence of a hand, and wherein a metallic core of the steering wheel is connected to a ground potential.
  • the sensor electrodes used here are a single or multi-layer structure of conductive sensor mats in the steering wheel rim. These sensor systems are also known as HOD sensors (Hands On Wheel Detection).
  • HOD sensors Halves On Wheel Detection
  • the presence of a hand can be detected via a capacitive measurement. This takes advantage of the fact that there is a capacitive coupling between the hand and the sensor electrode, the capacitance Cnand of which depends on the grip condition.
  • the task of an assigned sensor electronics or a measuring method used by it is to detect a change in the capacitance Cnand caused by a change in the handle state.
  • the particular difficulty here is that the capacity Cnand and in particular the changes to be recorded are very small compared to other internal capacities of the steering wheel.
  • Sensor systems for steering wheels of a motor vehicle for hand detection with capacitive sensor structures are basically known from the prior art.
  • DE 203 09 603 LI1 shows a steering wheel with sensor electrodes arranged in sectors, which make it possible to detect the approach and/or distance of a human hand and to assign it to a specific area of the steering wheel.
  • the WO 2016/087279 A1 discloses a steering wheel for a motor vehicle, with a capacitive sensor system, the sensor structure of which can also be operated as a heating structure, at least at times.
  • the steering wheel also has a metallic steering wheel core, which can be operated as an active shielding element and subjected to a defined electrical potential in order to reduce disruptive capacitive coupling of the sensor structure to the steering wheel core.
  • the steering wheel core is connected to a fixed potential in sensor electronics.
  • the impedance ZGND of this potential connection which is generally made to a ground potential GND, typically has a capacitive component of CGND > 100 nF.
  • the sensor electrodes and the steering wheel core are usually connected via connectors to a wiring harness that is routed to the HOD electronics and is also connected to it via connectors.
  • the method according to the present invention has the advantage over the previously described prior art of avoiding such errors.
  • a diagnosis of the connection of the steering wheel core to the ground potential is carried out during runtime by connecting at least one contact point of the steering wheel core to a second input of the sensor electronics, which carries out continuous monitoring of the applied potential.
  • Fig. 1 a schematic representation of a HOD sensor system for carrying out a method according to the invention in a first variant
  • Fig. 2 a schematic representation of a HOD sensor system for carrying out a method according to the invention in a first variant
  • Fig.3 a schematic representation of a HOD sensor system according to the state of the art as well as the relevant physical variables
  • Fig. 3 which shows the prior art, in a conventional HOD sensor system the at least one sensor electrode 4 of the sensor structure of the steering wheel 2 is connected to a first input/output 3.1 of the sensor electronics 3.
  • Fig. 1 shows a first embodiment of a HOD sensor system for carrying out a method according to the invention in a first variant.
  • the basic structure of the sensor system and the method for detecting the presence of a hand in a gripping area of the steering wheel are identical to that previously described with reference to Fig. 3.
  • connection there is also a connection between one of the line(s) 6 connecting the steering wheel core 5 to the ground potential GND and a further, second input 3.2 of the sensor electronics 3.
  • a capacitive voltage divider measurement is carried out, in which the capacitive coupling between a contact point 5.1 of the steering wheel core 5 and the sensor electrode 4 is used via the capacitance Ccore.
  • the sensor electrode 4 is supplied with a control signal, which is also followed by the voltage Ucore applied to the steering wheel core 5 due to the capacitive coupling Ccore. If the connection to the steering wheel core at one of the nodes 6.1 or 6.2 of line 6 is interrupted, the ratio of the voltage divider and thus the measured voltage Ucore changes. A loss of the steering wheel connection to the ground potential GND can be detected using a value range diagnosis.
  • the voltage divider is dominated by ZGND or CGND (CGND > 100 nF, Ccore ⁇ 1 nF).
  • CGND CGND > 100 nF, Ccore ⁇ 1 nF.
  • the connection to the fixed potential GND must be interrupted during the diagnostic measurement, which is implemented via an additional switch 8. Otherwise, the measured voltage change would be too small and thus not robust against other influences on the measurement.
  • FIG. 2 shows an alternative embodiment of an HOD sensor system for carrying out a method according to the invention.
  • the line 6 'of this further connection, in which the node 6.1 is located here, is, however, in contrast to the line 6 connected to the second input 3.2 and in which the node 6.2 is located, not directly connected to the ground potential GND.
  • a short-circuit diagnosis can be used to detect an interruption in the connection to node 6.1 or 6.2.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Steering Controls (AREA)

Abstract

The invention relates to a method for sensing the presence of a human hand (1) in a gripping region of a steering wheel (2) by means of a capacitive sensor system, the presence of the human hand (1) in a detection region of a sensor structure that comprises at least one sensor electrode (4) connected to a first input/output (3.1) of a sensor electronics unit (3) resulting in a change to a capacitive coupling (CHand) of the sensor electrode (4) with a reference potential compared to a reference state without the presence of the hand (1), with a metal core (5) of the steering wheel being connected to a ground potential (GND). According to the invention, the method is characterised in that a diagnosis of the connection of the steering wheel core (5) to the ground potential (GND) is carried out during runtime by connecting at least a first contact point (5.1) of the steering wheel core (5) to a second input (3.2) of the sensor electronics unit (3), which continuously monitors the applied potential.

Description

Verfahren zum Erkennen einer Anwesenheit einer menschlichen Hand in einem Greifbereich eines Lenkrads Method for detecting the presence of a human hand in a gripping area of a steering wheel

Die Erfindung betrifft ein Verfahren zum Erkennen einer Anwesenheit einer menschlichen Hand in einem Greifbereich eines Lenkrads mittels eines kapazitiven Sensorsystems, wobei die Anwesenheit einer menschlichen Hand in einem Detektionsbereich einer zumindest eine mit einem ersten Ein- /Ausgang einer Sensorelektronik verbundene Sensorelektrode umfassenden Sensorstruktur eine Änderung einer kapazitiven Kopplung der Sensorelektrode mit einem Bezugspotential gegenüber einem Referenzzustand ohne Anwesenheit einer Hand bewirkt, und wobei ein metallischer Kern des Lenkrades mit einem Massepotential verbunden ist. The invention relates to a method for detecting the presence of a human hand in a gripping area of a steering wheel by means of a capacitive sensor system, wherein the presence of a human hand in a detection area of a sensor structure comprising at least one sensor electrode connected to a first input/output of a sensor electronics represents a change in a capacitive coupling of the sensor electrode with a reference potential relative to a reference state without the presence of a hand, and wherein a metallic core of the steering wheel is connected to a ground potential.

Bei den hierbei verwendeten Sensorelektroden handelt es sich um einen, ein- oder mehrlagigen Aufbau von leitfähigen Sensormatten im Lenkradkranz. Diese Sensorsysteme werden auch als HOD Sensoren (Hands On wheel Detection) bezeichnet. Über eine kapazitive Messung kann hierbei die Anwesenheit einer Hand erkannt werden. Dabei wird ausgenutzt, dass eine kapazitive Kopplung zwischen Hand und Sensorelektrode besteht, deren Kapazität Cnand vom Griffzustand abhängt. Aufgabe einer zugeordneten Sensorelektronik bzw. eines durch diese verwendeten Messverfahrens ist es, eine durch Änderung des Griffzustandes hervorgerufene Änderung der Kapazität Cnand zu erfassen. Die besondere Schwierigkeit hierbei besteht darin, dass die Kapazität Cnand und insbesondere die zu erfassenden Änderungen derselben sehr klein sind im Vergleich zu sonstigen internen Kapazitäten des Lenkrads. Aus diesem Grunde bedient man sich zu ihrer Messung gerne sogenannter Integrationsverfahren, bei denen in mehreren aufeinander folgenden Zyklen kleine Ladungsmengen von dem Sensorelement, dessen Kapazitätswert relativ klein und veränderlich ist, auf einen Integrationskondensator mit einem bekannten festen und deutlich größeren Kapazitätswert übertragen werden. Die an dem Integrationskondensator nach einer vorgegebenen Anzahl solcher Integrationszyklen anliegende Spannung wird dann mittels eines A/D- Wandlers gemessen und zu einer Sensoramplitude verarbeitet, die wiederum ein direktes Maß für die Kapazität Cnand ist. Andere Einflüsse, die ebenfalls die gemessene Kapazität beeinflussen können, müssen daher soweit möglich konstant gehalten werden. Dazu wird insbesondere der Lenkradkern auf ein fixes Potential gelegt. The sensor electrodes used here are a single or multi-layer structure of conductive sensor mats in the steering wheel rim. These sensor systems are also known as HOD sensors (Hands On Wheel Detection). The presence of a hand can be detected via a capacitive measurement. This takes advantage of the fact that there is a capacitive coupling between the hand and the sensor electrode, the capacitance Cnand of which depends on the grip condition. The task of an assigned sensor electronics or a measuring method used by it is to detect a change in the capacitance Cnand caused by a change in the handle state. The particular difficulty here is that the capacity Cnand and in particular the changes to be recorded are very small compared to other internal capacities of the steering wheel. For this reason, so-called integration methods are often used to measure them, in which small amounts of charge are transferred from the sensor element, whose capacitance value is relatively small and variable, to an integration capacitor with a known fixed and significantly larger capacitance value in several successive cycles. The ones on the integration capacitor after a predetermined number of such The voltage present in the integration cycles is then measured using an A/D converter and processed into a sensor amplitude, which in turn is a direct measure of the capacitance Cnand. Other influences that can also influence the measured capacity must therefore be kept constant as far as possible. For this purpose, the steering wheel core in particular is placed at a fixed potential.

Sensorsysteme für Lenkräder eines Kraftfahrzeugs zur Hands-Erkennung mit kapazitiven Sensorstrukturen sind aus dem Stand der Technik grundsätzlich bekannt. So zeigt beispielsweise die DE 203 09 603 LI1 ein Lenkrad mit sektorweise angeordneten Sensorelektroden, die es ermöglichen, die Annäherung und/oder Entfernung einer menschlichen Hand erkennen und einem bestimmten Bereich des Lenkrades zuzuorden. Sensor systems for steering wheels of a motor vehicle for hand detection with capacitive sensor structures are basically known from the prior art. For example, DE 203 09 603 LI1 shows a steering wheel with sensor electrodes arranged in sectors, which make it possible to detect the approach and/or distance of a human hand and to assign it to a specific area of the steering wheel.

Die WO 2016/087279 A1 offenbart ein Lenkrad für ein Kraftfahrzeug, mit einem kapazitiven Sensorsystem, dessen Sensorstruktur zumindest zeitweise auch als Heizstruktur betrieben werden kann. Das Lenkrad weist ferner einen metallischen Lenkradkern auf, der als aktives Abschirmelement betrieben und mit einem definierten elektrischen Potential beaufschlagt werden kann, um eine störende kapazitive Kopplung der Sensorstruktur mit dem Lenkradkern zu reduzieren. The WO 2016/087279 A1 discloses a steering wheel for a motor vehicle, with a capacitive sensor system, the sensor structure of which can also be operated as a heating structure, at least at times. The steering wheel also has a metallic steering wheel core, which can be operated as an active shielding element and subjected to a defined electrical potential in order to reduce disruptive capacitive coupling of the sensor structure to the steering wheel core.

Aufgrund der gegenüber der Kapazität Cnand zwischen einer Hand und einer jeweiligen Sensorelektrode deutlich größeren Kapazität Ccore zwischen dem Lenkradkern und dieser Sensorelektrode, hätte eine Potentialänderung des Lenkradkerns eine störende Auswirkung auf die HOD Messung. Die zur Vermeidung dieses Problems vorgesehene Anbindung des Lenkradkerns an ein fixes Potential erfolgt in einer Sensorelektronik. Die Impedanz ZGND dieser Potential-Anbindung, die im Allgemeinen an ein Massepotential GND erfolgt, hat typischerweise einen kapazitiven Anteil von CGND > 100 nF. Die Sensorelektroden und der Lenkradkern werden üblicherweise über Steckverbinder mit einem Kabelbaum verbunden, der zur HOD Elektronik geführt und mit dieser ebenfalls über Steckverbinder verbunden ist. Due to the significantly larger capacitance Ccore between the steering wheel core and this sensor electrode compared to the capacitance Cnand between a hand and a respective sensor electrode, a change in potential of the steering wheel core would have a disturbing effect on the HOD measurement. To avoid this problem, the steering wheel core is connected to a fixed potential in sensor electronics. The impedance ZGND of this potential connection, which is generally made to a ground potential GND, typically has a capacitive component of CGND > 100 nF. The sensor electrodes and the steering wheel core are usually connected via connectors to a wiring harness that is routed to the HOD electronics and is also connected to it via connectors.

Dieser Sachverhalt sowie die relevanten physikalischen Größen sind in der Fig. 3 zum Stand der Technik schematisch dargestellt. This situation as well as the relevant physical quantities are shown schematically in Fig. 3 of the state of the art.

Fehlerhafte Kontaktierungen oder Kabelbrüche in der Potential-Anbindung des Lenkradkerns können zu deutlichen Änderungen der Impedanz ZGND und insbesondere des kapazitiven Anteils CGND derselben und somit zu falschen Messergebnissen führen. Incorrect contacts or cable breaks in the potential connection of the steering wheel core can lead to significant changes in the impedance ZGND and in particular the capacitive component CGND and thus to incorrect measurement results.

Das Verfahren gemäß der vorliegenden Erfindung hat gegenüber dem zuvor beschriebenen Stand der Technik den Vorteil, solche Fehler zu vermeiden. The method according to the present invention has the advantage over the previously described prior art of avoiding such errors.

Dies gelingt erfindungsgemäß dadurch, dass eine Diagnose der Verbindung des Lenkradkerns mit dem Massepotential zur Laufzeit durchgeführt wird, indem mindestens ein Kontaktpunkt des Lenkradkerns mit einem zweiten Eingang der Sensorelektronik verbunden ist, die eine laufende Überwachung des anliegenden Potentials ausführt. This is achieved according to the invention in that a diagnosis of the connection of the steering wheel core to the ground potential is carried out during runtime by connecting at least one contact point of the steering wheel core to a second input of the sensor electronics, which carries out continuous monitoring of the applied potential.

Weitere vorteilhafte Ausgestaltungen des erfindungsgemäßen Verfahrens ergeben sich aus den weiteren Unteransprüchen sowie aus der nachfolgenden Beschreibung einer möglichen Ausführung der Erfindung. Further advantageous embodiments of the method according to the invention emerge from the further subclaims and from the following description of a possible embodiment of the invention.

Nachfolgend ist die Erfindung unter Bezugnahme auf die beigefügte Zeichnung erläutert. Dabei zeigen: The invention is explained below with reference to the accompanying drawing. Show:

Fig. 1 : eine schematische Darstellung eines HOD Sensorsystems zur Ausführung eines erfindungsgemäßen Verfahrens in einer ersten Variante Fig. 1: a schematic representation of a HOD sensor system for carrying out a method according to the invention in a first variant

Fig. 2: eine schematische Darstellung eines HOD Sensorsystems zur Ausführung eines erfindungsgemäßen Verfahrens in einer ersten Variante Fig. 2: a schematic representation of a HOD sensor system for carrying out a method according to the invention in a first variant

Fig.3: eine schematische Darstellung eines HOD Sensorsystems nach dem Stand der Technik sowie die relevanten physikalischen Größen Fig.3: a schematic representation of a HOD sensor system according to the state of the art as well as the relevant physical variables

Wie in Fig. 3, die den Stand der Technik zeigt, zu sehen, ist bei einem herkömmlichen HOD Sensorsystem die zumindest eine Sensorelektrode 4 der Sensorstruktur des Lenkrades 2 mit einem ersten Ein-/Ausgang 3.1 der Sensorelektronik 3 verbunden. As can be seen in Fig. 3, which shows the prior art, in a conventional HOD sensor system the at least one sensor electrode 4 of the sensor structure of the steering wheel 2 is connected to a first input/output 3.1 of the sensor electronics 3.

Über diesen Ein-/Ausgang 3.1 der Sensorelektronik 3 kann eine durch die Anwesenheit einer menschlichen Hand 1 in einem Detektionsbereich der Sensorelektrode 4 hervorgerufene Änderung der kapazitiven Kopplung Cnand der Sensorelektrode 4 mit der Hand 1 erfasst werden. Die Kapazität Ccore zwischen der Sensorelektrode 4 und dem Lenkradkern 5 ist demgegenüber deutlich größer. Der Lenkradkern 5 selbst ist über eine oder mehrere Leitungen 6 mit einem festen Potential, welches im Allgemeinen ein Massepotential GND ist, verbunden. Diese Anbindung weist eine Impedanz ZGND mit einem kapazitiven Anteil von typischerweise CGND > 100 nF auf. Es sind sowohl einfache als auch mehrfache Kontaktierungen des Lenkradkerns 5 bekannt, wobei eine mehrfache Kontaktierung die Robustheit der Anbindung steigert. Eine gezielte Diagnose dieser Anbindung, insbesondere um eine Unterbrechung derselben zu erkennen, ist allerdings bisher nicht bekannt. In Fig. 1 ist eine erste Ausgestaltung eines HOD Sensorsystems zur Ausführung eines erfindungsgemäßen Verfahrens in einer ersten Variante gezeigt. Der grundsätzliche Aufbau des Sensorsystems und das Verfahren zum Erkennen der Anwesenheit einer Hand in einem Greifbereich des Lenkrads sind mit dem zuvor anhand Fig. 3 beschriebenen identisch. Via this input/output 3.1 of the sensor electronics 3, a change in the capacitive coupling Cnand of the sensor electrode 4 with the hand 1 caused by the presence of a human hand 1 in a detection area of the sensor electrode 4 can be detected. The capacitance Ccore between the sensor electrode 4 and the steering wheel core 5 is, in contrast, significantly larger. The steering wheel core 5 itself is connected via one or more lines 6 to a fixed potential, which is generally a ground potential GND. This connection has an impedance ZGND with a capacitive component of typically CGND > 100 nF. Both single and multiple contacts of the steering wheel core 5 are known, with multiple contacts increasing the robustness of the connection. However, a targeted diagnosis of this connection, in particular to detect an interruption in it, is not yet known. Fig. 1 shows a first embodiment of a HOD sensor system for carrying out a method according to the invention in a first variant. The basic structure of the sensor system and the method for detecting the presence of a hand in a gripping area of the steering wheel are identical to that previously described with reference to Fig. 3.

Zusätzlich ist hier aber noch eine Verbindung einer der den Lenkradkern 5 mit dem Massepotential GND verbindenden Leitung(en) 6 mit einem weiteren, zweiten Eingang 3.2 der Sensorelektronik 3 vorhanden. Mittels dieses zweiten Eingangs 3.2 der Sensorelektronik 3 wird eine kapazitive Spannungsteilermessung durchgeführt, bei der die kapazitive Kopplung zwischen einem Kontaktpunkt 5.1 des Lenkradkerns 5 und der Sensorelektrode 4 über die Kapazität Ccore genutzt wird. Dazu wird die Sensorelektrode 4 mit einem Ansteuersignal beaufschlagt, dem aufgrund der kapazitiven Kopplung Ccore auch die am Lenkradkern 5 anliegende Spannung Ucore folgt. Ist die Anbindung an den Lenkradkern an einem der Knoten 6.1 oder 6.2 der Leitung 6 unterbrochen, verändert sich das Verhältnis des Spannungsteilers und somit die gemessene Spannung Ucore. Über eine Wertebereichsdiagnose kann ein Verlust der Lenkradanbindung an das Massepotential GND erkannt werden. In addition, there is also a connection between one of the line(s) 6 connecting the steering wheel core 5 to the ground potential GND and a further, second input 3.2 of the sensor electronics 3. Using this second input 3.2 of the sensor electronics 3, a capacitive voltage divider measurement is carried out, in which the capacitive coupling between a contact point 5.1 of the steering wheel core 5 and the sensor electrode 4 is used via the capacitance Ccore. For this purpose, the sensor electrode 4 is supplied with a control signal, which is also followed by the voltage Ucore applied to the steering wheel core 5 due to the capacitive coupling Ccore. If the connection to the steering wheel core at one of the nodes 6.1 or 6.2 of line 6 is interrupted, the ratio of the voltage divider and thus the measured voltage Ucore changes. A loss of the steering wheel connection to the ground potential GND can be detected using a value range diagnosis.

Allerdings wird der Spannungsteiler durch ZGND bzw. CGND dominiert (CGND > 100 nF, Ccore ~ 1 nF). Um eine Unterbrechung an Knoten 6.2 sicher zu erkennen, muss die Verbindung zum fixen Potential GND während der Diagnosemessung unterbrochen werden, was über einen zusätzlichen Schalter 8 realisiert wird. Andernfalls wäre die gemessene Spannungsänderung zu klein und somit nicht robust gegenüber anderen Einflüssen auf die Messung. However, the voltage divider is dominated by ZGND or CGND (CGND > 100 nF, Ccore ~ 1 nF). In order to reliably detect an interruption at node 6.2, the connection to the fixed potential GND must be interrupted during the diagnostic measurement, which is implemented via an additional switch 8. Otherwise, the measured voltage change would be too small and thus not robust against other influences on the measurement.

In Fig. 2 ist eine alternative Ausgestaltung eines HOD Sensorsystems zur Ausführung eines erfindungsgemäßen Verfahrens gezeigt. Im Unterschied zu der in Fig. 1 dargestellten Ausführung ist hier neben der Verbindung eines ersten Kontaktpunktes 5.1 des Lenkradkerns 5 mit dem zweiten Eingang 3.2 der Sensorelektronik 3 noch eine weitere Verbindung eines zweiten Kontaktpunktes 5.2 des Lenkradkerns 5 mit einem weiteren, dritten Eingang 3.3 der Sensorelektronik 3 vorhanden. Die Leitung 6‘ dieser weiteren Verbindung, in der hier der Knoten 6.1 liegt, ist jedoch im Unterschied zu der mit dem zweiten Eingang 3.2 verbundenen Leitung 6, in der der Knoten 6.2 liegt, nicht direkt mit dem Massepotential GND verbunden. Durch eine Kurzschlussdiagnose kann eine Unterbrechung der Anbindung an den Knoten 6.1 oder 6.2 erkannt werden. 2 shows an alternative embodiment of an HOD sensor system for carrying out a method according to the invention. In contrast to the embodiment shown in FIG. 1, here there is one next to the connection first contact point 5.1 of the steering wheel core 5 with the second input 3.2 of the sensor electronics 3 there is also a further connection of a second contact point 5.2 of the steering wheel core 5 with a further, third input 3.3 of the sensor electronics 3. The line 6 'of this further connection, in which the node 6.1 is located here, is, however, in contrast to the line 6 connected to the second input 3.2 and in which the node 6.2 is located, not directly connected to the ground potential GND. A short-circuit diagnosis can be used to detect an interruption in the connection to node 6.1 or 6.2.

Claims

Patentansprüche Patent claims 1 . Verfahren zum Erkennen einer Anwesenheit einer menschlichen Hand (1 ) in einem Greifbereich eines Lenkrads (2) mittels eines kapazitiven Sensorsystems, wobei die Anwesenheit der menschlichen Hand (1 ) in einem Detektionsbereich einer zumindest eine mit einem ersten Ein- /Ausgang (3.1 ) einer Sensorelektronik (3) verbundene Sensorelektrode (4) umfassenden Sensorstruktur eine Änderung einer kapazitiven Kopplung CHand der Sensorelektrode (4) mit einem Bezugspotential gegenüber einem Referenzzustand ohne Anwesenheit der Hand (1 ) bewirkt, und wobei ein metallischer Kern (5) des Lenkrades mit einem Massepotential (GND) verbunden ist, dadurch gekennzeichnet, dass eine Diagnose der Verbindung (6) des Lenkradkerns (5) mit dem Massepotential (GND) zur Laufzeit durchgeführt wird, indem mindestens ein erster Kontaktpunkt (5.1 ) des Lenkradkerns (5) mit einem zweiten Eingang (3.2) der Sensorelektronik (3) verbunden ist, der eine laufende Überwachung des anliegenden Potentials ausführt. 1. Method for detecting the presence of a human hand (1) in a gripping area of a steering wheel (2) by means of a capacitive sensor system, wherein the presence of the human hand (1) in a detection area of a sensor structure comprising at least one sensor electrode (4) connected to a first input/output (3.1) of a sensor electronics system (3) causes a change in a capacitive coupling CHand of the sensor electrode (4) with a reference potential compared to a reference state without the presence of the hand (1), and wherein a metallic core (5) of the steering wheel is connected to a ground potential (GND), characterized in that a diagnosis of the connection (6) of the steering wheel core (5) with the ground potential (GND) is carried out at runtime by connecting at least a first contact point (5.1) of the steering wheel core (5) to a second input (3.2) of the sensor electronics system (3), which carries out continuous monitoring of the applied potential. 2. Verfahren nach Anspruch 1 , dadurch gekennzeichnet, dass mittels des zweiten Eingangs (3.2) der Sensorelektronik (3) eine kapazitive Spannungsteilermessung durchgeführt wird, bei der die kapazitive Kopplung zwischen dem Lenkradkern (5) und der Sensorelektrode (4) über die Kapazität Ccore genutzt wird. 2. The method according to claim 1, characterized in that a capacitive voltage divider measurement is carried out using the second input (3.2) of the sensor electronics (3), in which the capacitive coupling between the steering wheel core (5) and the sensor electrode (4) via the capacitance Ccore is being used. 3. Verfahren nach Anspruch 2, dadurch gekennzeichnet, dass die Sensorelektrode (4) mit einem Ansteuersignal beaufschlagt wird, dem aufgrund der kapazitiven Kopplung Ccore auch die am Lenkradkern (5) anliegende Spannung Ucore folgt. 3. The method according to claim 2, characterized in that the sensor electrode (4) is supplied with a control signal, which is also followed by the voltage Ucore applied to the steering wheel core (5) due to the capacitive coupling Ccore. 4. Verfahren nach Anspruch 2 oder 3, dadurch gekennzeichnet, dass die Verbindung (6) des Lenkradkerns (5) mit dem Massepotential (GND) während der Diagnosemessung über einen zusätzlichen Schalter (8) unterbrochen wird. Verfahren nach Anspruch 1 , dadurch gekennzeichnet, dass ein zweiter Kontaktpunkt (5.2) des Lenkradkerns (5) mit einem dritten Eingang (3.3) der Sensorelektronik (3) verbunden ist, und dass durch eine Kurzschlussdiagnose eine Unterbrechung der Verbindung (6) des Lenkradkerns (5) mit dem Massepotential (GND) oder der Verbindung (6‘) des Lenkradkerns (5) mit dem dritten Eingang (3.3) der Sensorelektronik (3) erkannt wird. 4. Method according to claim 2 or 3, characterized in that the connection (6) of the steering wheel core (5) to the ground potential (GND) during the diagnostic measurement via an additional switch (8) is interrupted. Method according to claim 1, characterized in that a second contact point (5.2) of the steering wheel core (5) is connected to a third input (3.3) of the sensor electronics (3), and that an interruption of the connection (6) of the steering wheel core (5) to the ground potential (GND) or the connection (6') of the steering wheel core (5) to the third input (3.3) of the sensor electronics (3) is detected by a short-circuit diagnosis.
EP23777247.0A 2022-09-29 2023-09-26 Method for sensing the presence of a human hand in a gripping region of a steering wheel Pending EP4594159A1 (en)

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DE102022003602.9A DE102022003602A1 (en) 2022-09-29 2022-09-29 Method for detecting the presence of a human hand in a gripping area of a steering wheel
PCT/EP2023/076487 WO2024068593A1 (en) 2022-09-29 2023-09-26 Method for sensing the presence of a human hand in a gripping region of a steering wheel

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See also references of WO2024068593A1

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