Iee International Electronics and Engineering S.a.

Thomas Faber

Laurent Lamesch

Michael Puetz

Baptiste Anti

Michael Pütz

Thomas Stifter

Gianluca Favalli

Andreas Fox

Christoph Wendt

Frank Althaus

Tobias Justinger

Thomas Meyers

Erik Holzapfel

Miguel Ribeiro

Alan Koehler

Oliver Lion

Heinrich Gierens

Valentin Catalin Mica

Johnny Lorang

An impedance measurement circuit for determining a complex impedance of a capacitive sensor having at least one sense electrode operable in loading mode and at least one guard electrode. The measurement circuit includes: a pulse generator unit for providing a periodic electric measurement signal and a periodic electric guard signal; a signal sensing circuit for sensing a sense current flowing through the at least one sense electrode or the sense electrodes in response to the pulse generator unit measurement signal; and a control and evaluation unit. The control and evaluation unit is configured for determining a complex impedance from the determined sense currents with reference to a complex reference potential.

Low-cost, high measurement speed capacitive sensing circuit for loading mode operation of capacitive sensors

A sensing system for hand or body part positioning detection on an object, particularly on a rim of a steering wheel, includes at least one electrically conducting signal line that is arrangeable on a surface of the object with a priori knowledge about a relation between a distance of any portion of the at least one signal line from a reference point and information on a position on the object, a signal voltage source for providing a time-dependent measurement signal to be traveling along the signal line, and a control and evaluation unit. From a received reflected measurement signal, the control and evaluation unit determines a position or positions on the object of a portion or portions of the signal line at least partially reflecting the measurement signal. Based on the determined position or positions, a hand or body part positioning on the object is determined.

TDR-based system for hand or body part positioning detection on an object, particularly on a steering wheel

A capacitive measurement circuit for a capacitive sensing device having a plurality of antenna electrodes includes: a measurement signal voltage source, a remotely controllable switching unit, and a current measurement circuit. The switching unit includes a plurality of ports and switching members that are configured to provide connections between selected ports. The measurement signal voltage source and the current measurement circuit are operatively connected to a distinct port. Each antenna electrode is individually connectable to a distinct port. The switching unit is configured to connect, within a same measurement cycle, each of the antenna electrodes to the voltage output port and the current measurement circuit for loading mode operation. The switching unit is further configured to connect at least one of the antenna electrodes to the voltage output port and at least one other antenna electrode of the antenna electrodes to the current measurement circuit for coupling mode operation.

Capacitive sensor device with selective loading and coupling measurement mode

A method of operating a capacitive sensing device that includes exactly two electrically conductive antenna electrodes, which are placeable in two layers at a vehicle steering wheel rim, and a current measurement circuit for determining complex electric currents in the antenna electrodes. The method includes at least the following steps for constituting a measurement cycle: operating each one of the exactly two antenna electrodes in loading mode and determine the complex impedance of the respective antenna electrode; and generating a classification signal that is indicative of a present scenario, based on a fulfillment of at least one predetermined condition concerning at least one characteristic quantity of the first complex impedance as well as of the second complex impedance.

Device and method for detecting a hand grasp with a two-zone sensor in the steering wheel

An impedance measurement circuit for determining a complex impedance of a capacitive sensor that is configured for employing at least one electric heater member as an electrode to be operated in loading mode. The measurement circuit includes: a signal generating unit for providing an electric measurement signal; a signal sensing circuit measuring current through the at least one electric heater member; an electric heater member connection circuit comprising a plurality of MOSFETs for selectively electrically connecting the electric heater member either to the signal sensing circuit for complex impedance measurement or to a DC electric power unit for heating purposes; and a control and evaluation unit that is configured for controlling a switching status of the plurality of MOSFETs according to a predefined sequence, and for determining a complex impedance from the determined currents with reference to a complex reference potential during predefined stages of the predefined sequence.

Low-cost, protected capacitive sensing circuit for loading mode operation of capacitive sensors employing heater members

A sensing system and method of recognizing a hand gesture established by a sequence of hand touch positionings on an object. The method includes at least steps of: providing to a signal line a time-dependent measurement signal; receiving the measurement signal after being at least partially reflected by at least one portion of the signal line; determining positions on the object of the portions of the signal line that have reflected the measurement signal; comparing an obtained plurality of stored successively determined positions on the object with at least one predefined pattern of successive positions to derive a measure of similarity; and providing an output signal that is indicative of the predefined pattern of successive positions if the derived measure of similarity is lower than a predefined threshold value.

TDR-based system for detection of hand touch positionings on an object, particularly on a steering wheel for the purpose of hand gesture recognition

A method of detecting a hand positioning on a steering wheel using a sensing system having an electrically conducting signal line on a rim of the steering wheel with a priori knowledge about a relation between a distance of any portion of the signal line from a reference point and information on a position on the rim, and which further includes an electric impedance change of predefined magnitude that is permanently arranged at a predefined position along the signal line, a signal voltage source, and a control and evaluation unit. From a received measurement signal traveling along the signal line and having been reflected by the electric impedance change and by another portion or portions of the signal line, a reference travel time is determined. A position or positions on the rim of the other portion or portions of the signal line can then be determined.

TDR-based system and method for hand detection on a steering wheel with elimination of aging and environmental effects

A method of operating a capacitive sensing device that includes a capacitive sensor having at least one sense electrode, a measurement signal source for providing an alternating electric measurement signal with at least three fixed predefined signal frequencies to the at least one sense electrode, and an impedance measurement circuit for determining an unknown complex impedance of the at least one sense electrode from a response to the provided electric measurement signal. The method includes, for each predefined signal frequency: determining statistical quantities and signal parameters regarding a number of determined momentary values of an unknown complex impedance; eliminating portions up to a predefined hand touch movement lower limit frequency and from a predefined high-frequency limit down to a predefined hand touch movement upper limit frequency; excluding statistical outliers from determined momentary values; and using an eliminated frequency portion for calculating a momentary reference value for the unknown complex impedance.

Robust 'hands on steering wheel' classification based on a relative measurement system

A method of operating a capacitive sensing device for diagnosing a galvanic connection of at least one guard electrode. The capacitive sensing device includes at least one sense-guard capacitive sensor and a capacitive measurement circuit. The sense-guard capacitive sensor includes a first electrically conductive sense electrode and a first electrically conductive guard electrode and at least a second electrically conductive sense electrode, which is galvanically separated from the first sense electrode, and at least a second electrically conductive guard electrode. Each of the guard electrodes is proximally arranged to at least one of the sense electrodes and is galvanically separated from each of the sense electrodes. The method uses a calculated difference of imaginary parts of complex sense currents resulting from coupling mode measurements between at least two of the sense electrodes for assessing a status of the galvanic connection of the guard electrodes.

Capacitive sensor guard diagnostics from redundant coupling measurement

A sensor arrangement for capacitive position detection of a hand on a steering wheel. The sensor arrangement includes: a plurality of capacitive sensors disposed along a detection surface, which is an outer surface of the steering wheel, each sensor having at least one sensor electrode; and a measurement device electrically connected to the sensors. In order to increase the reliability of capacitive hand detection on a steering wheel, the measurement device is adapted to perform a sequence of detection operations, and in each detection operation, to activate at least one sensor by applying a detection signal to its at least one sensor electrode in order to capacitively detect the hand while grounding at least one other sensor by connecting at least one of its sensor electrodes to ground, and to activate different sensors in consecutive detection operations.

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Schweich, Germany

Thomas Faber