Detection of the presence of a hand on an operating device

Abstract

An operating device for a machine is provided, for example for an agricultural or constructional vehicle. The operating device (10) comprises a handle (11) configured to be gripped by a hand (100) of a user. The operating device (10) comprises a presence detector (15) configured to detect a presence of the hand (100) on the handle (11). The presence detector (15) comprises a radar sensor (20) providing a radar sensor signal, wherein the presence detector (15) is configured to estimate the presence of the hand (100) using the radar sensor signal.

Description

[0001]DETECTION OF THE PRESENCE OF A HAND ON AN OPERATING DEVICE FIELD OF THE INVENTION The present invention relates to an operating device for a machine, the operating device comprising a handle and a presence detector. It further relates to a method of estimating a presence of a hand of a user on an operating device. A respective machine and computer program may further be provided. BACKGROUND Operating elements such as joysticks are regularly used to control functions of a machine, such as of a construction vehicle or agricultural vehicle. In order to reduce operating errors, such as an undesired actuation of the operating element, the presence of the user's hand on the operating element can be detected. The operating element may then only become active once the presence of the hand is detected. It is thus desirable to reliably detect the presence of the hand in order to ensure that the user is not prevented from actuating the operating element (avoidance of false-negative detections) and to distinguish the hand against other objects coming into contact with the operating element (avoiding false-positive detections). To solve this problem, metallic elements can be provided in the gripping area of the joystick. A capacitive measurement can then be used to detect if a hand is present on the joystick. However, such measurement may be disturbed if the user wears gloves on his hands. Further, such capacitive detection may suffer from electromagnetic incompatibility, for example as the metallic elements may act as antennas. Also, respective capacitive measurements suffer from a dependency on temperature and humidity. The capacitive detection may furthermore recognize a metallic body as a hand, which may result in a false-positive detection. Resolving these problems may be associated with a high cost and effort. P 85022 INT - Kahler Käck Mollekopf - 85022int.Nachanmeldefassung.clean It is therefore desirable to reliably detect the presence of a hand on such operating device, such as a joystick, without the respective drawbacks. It is particularly desirable to reduce the number of false-positive detections and false-negative detections when performing such presence detection of the user's hand. Document DE 102021214415 A1 discloses an input device for inputting a command, the input device having an operating element for inputting the command, the input device further having a carrier plate, the operating element being arranged movably on a first side of the carrier plate. Furthermore, the input device has an actuator for moving the operating element and the carrier plate between an initial position and an operating position. SUMMARY Accordingly, there is a need to mitigate at least some of the drawbacks mentioned above and to provide an improved detection of the hand of a user on an operating element. This need is met by the features of the independent claims. The dependent claims describe embodiments of the invention. According to an embodiment of the invention, an operating device for a machine is provided. The operating device comprises a handle that is configured to be gripped by a hand of a user. The operating device comprises a presence detector configured to detect a presence of the hand on the handle. The presence detector comprises a radar sensor providing a radar sensor signal. The presence detector is configured to estimate the presence of the hand using the radar sensor signal. The reliability of the presence detection of the user's hand may thereby improved. As the radar waves may penetrate a casing of the handle, no openings need to be provided in the handle's casing and in particular no metal plates need to be mounted in the handle's casing. Accordingly, protection against harsh environments may be improved and manufacturing of the operating device may be facilitated. Further, as no metal plates need to be present, electromagnetic interference may be avoided. At the same time, false-positive detection due to, e.g., metallic objects, may be prevented. Even further, the detection may not be affected by a glove worn on the user's hand. Even further, the detection may be rather insensitive to temperature and humidity. P 85022 INT - Kahler Käck Mollekopf - 85022int.Nachanmeldefassung.clean Accordingly, the reliability of detection of the user's hand may be improved significantly. Conventionally, radar sensors are used to detect objects at larger distances, e.g. larger than 50 cm. Further, known radar sensors suffer from an effect termed DC peak, which occurs for distances close to the radar sensors and thus obscures objects in close range of the radar sensor. It is therefore counter-intuitive to employ such radar sensor for detecting the presence of a user’s hand of the handle, as the hand touches the handle and will thus be very close to any radar sensor present in the handle, e.g. closer than 2 cm. Although the radar signal at such distance is hidden by the DC peak, it has surprisingly been found that such radar sensor can nevertheless be employed for a reliable presence detection of the user’s hand on the handle. The presence detector may be configured to detect if the user's hand grips or grasps the handle (e.g. the palm of the hand adapts to the shape of the handle and the fingers hold the handle). The estimation of the presence of the hand may be based on the radar sensor signal. This may comprise that the radar sensor signal is processed in order to derive an estimate if the user's hand is gripping the handle or not. The handle may be actuatable by a user to control a function of the machine, and / or an operating element on the handle may be actuatable by the user to control a function of the machine (such as a button, a wheel, and / or the like provided on the handle). As an example, actuation of the handle may control a forward and / or backward motion of the machine, a steering direction of the machine, and / or the like. The handle may be provided on or may form part of a lever of the operating device. In particular, the operating device may be a joystick or a control lever, and the handle may be a respective joystick handle or lever handle. Besides an implementation as a joystick, the operating element may for example be implemented as a throttle lever, thrust lever, or the like. In an embodiment, the radar sensor is mounted to the handle. Preferably, it is mounted inside the handle. A radar wave transmitter and / or a radar wave receiver, or a transceiver, of the radar sensor may for example be mounted inside the handle. A compact configuration that is protected from environmental conditions may thus be obtained. P 85022 INT - Kahler Käck Mollekopf - 85022int.Nachanmeldefassung.clean The radar sensor may have a radiation angle and / or a detection angle for radar waves, and the handle may have a defined gripping position for the hand of the user. The radar sensor may be arranged on the handle such that if the handle is gripped by the hand in the gripping position, the radiation angle and / or the detection angle may be covered by the hand of the user. It may be at least partly covered or fully covered. ‘Arranged on the handle’ may comprise an arrangement on or at the handle. In particular, in the gripping position, a field of view of the radar sensor may be covered by the hand of the user. The radar sensor may for example be arranged such that in the gripping position, the hand completely covers the field of view of the radar sensor. An improved sensor response and an improved reliability of the detection may thereby be achieved. The radiation angle and the detection angle may in particular be a solid angle or spatial angle. Such angle or field of view is generally defined for a given radar sensor, for example in the radar sensor specification. The handle may comprise a gripping area that is bent, and the bent gripping area may be arranged to be covered by the hand of the user when the hand is in the gripping position. The radar sensor may be arranged such that the bent gripping area lies within the radiation angle and / or the detection angle of the radar sensor, in particular such that the bent gripping area lies within the field of view of the radar sensor. The arrangement may in particular be such that the radar waves emitted by the radar sensor and / or received by the radar sensor pass through the bent gripping area. Accordingly, in such configuration, if a flat object abuts against the gripping area, the gripping area and thus field of view of the radar sensor may not fully or consistently be covered by the object, so that a distinction between the user's hand and the object may be facilitated. Radar waves may in particular pass through the bent portions of the bent gripping area and may not be attenuated by a flat object, so that a wrong detection of a gripping of the handle by a hand may be avoided. The bent area may for example cover the field of view of the radar sensor, it may in particular cover the (spatial) angle over which the radar waves are emitted by the radar sensor. The bent area may be bent or have a curvature around a central (longitudinal) axis of the handle. The hand may abut the bent area (e.g. be in contact with the handle over the (whole) bent area) if the user’s hand grips the handle in the gripping position. P 85022 INT - Kahler Käck Mollekopf - 85022int.Nachanmeldefassung.clean For example, in a cross-section through a longitudinal axis of the handle, the bent area may bend at least over 15%, preferably at least over 25%, 30%, or more of the circumference of the outer surface of the handle. By providing the radar sensor with a field of view such that a respective bent area of the handle lies in the field of view, detection reliability for the gripping of the handle by the user's hand may be improved. In an embodiment, the presence detector may be configured to generate a range spectrum from the radar sensor signal. The range spectrum may indicate a signal level of the detected radar waves for different distances from the radar sensor. The presence of the hand may be estimated from the range spectrum. Such range spectrum may allow distinguishing between the distances of objects in the field of view of the radar sensor. By employing such range spectrum in the detection, the accuracy of the detection may further be improved. Such range spectrum may for example be generated by the radar sensor itself or any other processing unit of the presence detector. The range spectrum may for example be a frequency domain signal in which frequencies are indicative of (in particular proportional to) a distance or range from the radar sensor. A level of the range spectrum at a respective frequency may indicate how strongly the radar wave is reflected back to the radar sensor at the corresponding distance from the sensor. It should be clear that the range spectrum may not need to be calibrated and may simply indicate a level at different frequencies, which correspond to respective distances to the radar sensor. For example, reflected radar waves may be detected by a respective receiver (or transceiver) of the radar sensor and the corresponding signals may be processed and may be transformed into the frequency domain (e.g. using a discrete Fourier transform, e.g. a fast Fourier transform) to obtain the range spectrum. Obtaining a range spectrum from a radar sensor is generally known in the art, and any of the respectively known methods may be employed here. Such range spectrum may be obtained repeatedly, e.g. for different portions of the radar signal during operation. Optionally, in an embodiment, the presence detector is configured to estimate the presence of the hand on the handle (in particular the gripping of the handle) based on an attenuation of a signal level of radar waves detected by the radar sensor, the attenuation being caused by the presence of the hand on the handle. Conventionally, radar is used to detect a position of an object by detecting radar waves reflected back from the object. Contrary to the general use of such radar sensor, the attenuation of the radar waves may be evaluated in accordance with embodiments of the invention to estimate the presence P 85022 INT - Kahler Käck Mollekopf - 85022int.Nachanmeldefassung.clean of the hand. Such counter-intuitive approach may provide an improved accuracy at the short distance of the hand to the radar sensor that may be present in the embodiments of the operating device. Preferably, the presence detector estimates the presence of the hand from the range spectrum based on an attenuation of the level (e.g. power or intensity) of detected radar waves at one or more distances in the range spectrum. As mentioned above, the distances correspond to frequencies in the range spectrum, and the level at the respective frequencies may be evaluated. Preferably, the presence of the hand is estimated based on the attenuation of the level of the range spectrum for distances larger than a minimum distance. To detect the presence of the hand, distances of the range spectrum may thus be evaluated that are larger than the distance of the object (hand) to be detected if the object (hand) is present on the handle, e.g. gripping the handle. Surprisingly, it has been found that by such approach, the presence detection may further be improved. In particular, it has been found that the range spectrum obtained from the radar sensor signal may suffer from a relatively large DC peak, which may be due to parasitic effects. Such peak may interfere with the detection of the hand being close to the radar sensor. Such problems may be avoided by evaluating the range spectrum at distances larger than the minimum distance instead of using signal levels at the expected distance of the hand on the handle. The minimum distance may for example be selected from a range between 5 cm and 3 m, preferably between 10 cm and 1 m, e.g. between 20 cm and 1 m. The minimum distance may for example be set to a value of 20 cm or higher, 40 cm or higher, 50 cm or higher and the like. It may be selected in accordance with the geometric configuration and the sensor properties. In any case, the minimum distance may be larger than the distance to the hand of the user when the hand grips the handle (such distance may only be 0.5 to 2 cm). In an embodiment, the presence detector is configured to derive a presence signal from the radar sensor signal. The presence signal may in particular be derived from one or more range spectra, such as the range spectrum mentioned above. Range spectra may be repeatedly processed to obtain a presence score for each range spectrum, and the presence scores may form the presence signal. The presence of the hand may be estimated from a value of the presence signal, for example by comparing the presence signal to a presence threshold. By such processing of the measurements taken by the P 85022 INT - Kahler Käck Mollekopf - 85022int.Nachanmeldefassung.clean radar sensor into a simple presence signal, a simple measure for the presence of the hand may be provided and the evaluation thereof may be facilitated. For example, the presence signal may be determined by summing the range spectrum over a predetermined range of distances (which may correspond to a respective range of frequencies in the range spectrum). The distance range may for example start at the respective minimum distance and may include a range of distances or all distances of the range spectrum larger than the minimum distance. For example, if the range spectrum extends up to a maximum distance of 3 m, the range between the minimum distance, e.g.40 cm, and the maximum distance, e.g.3 m, may be summed to obtain the presence signal, or a sub range thereof may be summed to obtain the presence signal. Prior to summing, an absolute value may be formed of the range spectrum to avoid negative interference. For example, a signal power or signal magnitude of the range spectrum may be summed, for example integrated, over the respective frequency range or spectral range corresponding to the predetermined range of distances. If the radar sensor comprises plural radar wave receivers (or transceivers), the range spectra of some or of all such receivers may be used to derive the presence signal. The absolute values of the range spectra of all respective receiver channels may for example be summed to obtain the presence signal. As an example, from the signal detected by the radar wave receiver, an inter-frequency signal may be formed (e.g. by multiplication with the radar signal to be transmitted and low-pass filtering), and the resulting signal may be transformed into the frequency domain to obtain the range spectrum. An integrator may then be used to integrate the absolute signal values of the range spectrum above a certain minimum frequency corresponding to a minimum distance. This may for example be implemented by a high- pass filter that only passes the components of the inter-frequency signal above a cut-off frequency corresponding to the minimum distance, and a respective integrator circuit. The presence signal may thus be obtained in a computationally efficient way. Such processing may be implemented by means of electronic circuits and / or a digital processing unit. It should be clear that the range spectrum may be processed in form of a signal by analog and / or digital signal processing. The range spectrum may thus also be provided in form of a range signal. It only matters that the respective range spectrum or range P 85022 INT - Kahler Käck Mollekopf - 85022int.Nachanmeldefassung.clean signal comprises information, in whatever form, on the level of detected radar waves reflected at different distances from the radar sensor. The presence detector may be configured to compare the presence signal to a predetermined threshold (which may also be a dynamic threshold). The presence detector may determine the hand to be present on the handle if the presence signal meets or passes the predetermined threshold. A simple way of presence detection may thus be provided. It should be clear that depending on the definition of the presence signal, passing of the threshold may mean that the presence signal raises above the threshold, or that the presence signal drops below the threshold upon the user's hand gripping the handle. The operating device may further be configured to activate one or more functions that are operable by an actuation of the handle and / or by an actuation of an operating element provided on the handle if the presence detector indicates the presence of the user's hand on the handle, i.e. if the user has gripped the handle. Such function may for example be the control of a movement of the machine (throttle control, directional control and the like) or may control a tool of the machine, such an excavator arm or the like. In some embodiments, the operating device may comprise a controller configured to perform the estimation of the presence of the hand based on the radar sensor signal. Such controller may be provided within the operating device, or may be provided at another location on the machine. Such controller may perform any of the control and / or processing steps described herein. For example, the radar signal and / or the range spectrum may be transmitted from the radar sensor to the controller, and the controller may perform the respective evaluation to estimate the presence of the hand and may optionally perform the activation of the one or more functions upon detecting a presence of the hand. In an embodiment, the radar sensor employs a frequency-modulated continuous wave (FMCW) radar. Such type of radar may provide a reliable detection of distances in a short range. Preferably, the radar sensor comprises an integrated circuit that includes a radar transmitter and a radar receiver, or a radar transceiver. A compact configuration that is P 85022 INT - Kahler Käck Mollekopf - 85022int.Nachanmeldefassung.clean suitable for integration into the handle of the operating device may thus be obtained. The radar sensor may comprise a monolithic microwave integrated circuit (MMIC). The radar sensor may in particular be an integrated device that is implemented on a chip. Furthermore, the integrated device may further include sending and receiving antennas, or a combined antenna. Such antenna may be provided on the chip or in a package of the integrated circuit. The radar sensor may thus be provided with a small form factor and implementation may be facilitated, as there is for example no need for antenna design and the like. Such integrated radar sensor may further benefit from reduced power consumption. Preferably, the radar sensor is configured to operate at a frequency of the radar waves at which a hand has a relatively high absorption. For example, it may operate within a frequency range of 10 to 100 GHz, preferably between 50 and 80 GHz. As an example, a 60 GHz radar sensor may be employed. The reliability of detection may thereby be improved, as larger changes in the level of the range spectrum may be expected when the hand grips the handle. The radar sensor may be configured to emit a radar wave and to detect the radar wave after reflection by an object, wherein the radar sensor may further be configured to generate a radar sensor signal that is indicative of a distance of the object from the radar sensor. The radar sensor signal may accordingly comprise distance information about a distance of one or more objects from which the radar wave has been reflected. For example, the radar sensor may be configured to emit a radar wave having a change in frequence over time, in particular a frequency ramp or chirp. The frequency of such radar wave may for example be modulated by a sine wave, a sawtooth wave, a triangle wave or the like. According to a further embodiment of the invention, a machine, in particular a vehicle, comprising an operating device having any of the configurations disclosed herein is provided. The operating device is configured and arranged to control one or more functions of the machine by actuation of the handle and / or by actuation of one or more operating elements disposed on the handle. Such machine may for example be an agricultural vehicle, a construction vehicle, an industrial vehicle, or the like. P 85022 INT - Kahler Käck Mollekopf - 85022int.Nachanmeldefassung.clean According to a further embodiment of the invention, a method of estimating a presence of a hand of a user on an operating device is provided. The operating device comprises a handle that is configured to be gripped by the hand of the user, wherein the operating device comprises a presence detector configured to detect a presence of the hand on the handle, wherein the presence detector comprises a radar sensor providing a radar sensor signal. The method comprises obtaining a radar sensor signal generated by the radar sensor and estimating the presence of the hand using the radar sensor signal. The radar sensor signal may be obtained by receiving (e.g. from the radar sensor), measuring (e.g. by the radar sensor) or calculating (e.g. from raw data received from the radar sensor). The method may comprise any steps described herein with respect to the operating device. It may in particular comprise any combination of the steps described with respect to estimating the presence of the user’s hand on the handle of the operating device. According to a further embodiment, a computer program for estimating the presence of a hand of a user on an operating device is provided. The operating device comprises a handle that is configured to be gripped by the hand of the user, wherein the operating device comprises a presence detector configured to detect a presence of the hand on the handle. The presence detector comprises a radar sensor providing a radar sensor signal. The computer program comprises control instructions which, when executed by a processing unit of an operating device that is coupled to the radar sensor, cause the processing unit to perform any of the methods described herein. Such computer program, in particular the respective control instructions, may be provided on a volatile or non-volatile storage medium or data carrier, and / or may be provided via a communication connection, such as a wired or wireless network connection. By such machine, method, or computer program, advantages may be achieved that correspond to the advantages outlined further above with respect to the operating device. It is to be understood that the features mentioned above and those yet to be explained below can be used not only in the respective combinations indicated, but also in other combinations or in isolation, without leaving the scope of the present invention. In P 85022 INT - Kahler Käck Mollekopf - 85022int.Nachanmeldefassung.clean particular, the features of the different aspects and embodiments of the invention can be combined with each other unless noted to the contrary. BRIEF DESCRIPTION OF THE DRAWINGS The forgoing and other features and advantages of the invention will become further apparent from the following detailed description read in conjunction with the accompanying drawings. In the drawings, like reference numerals refer to like elements. Fig.1 is a schematic drawing showing a side view of an operating device according to an embodiment. Fig.2 is a schematic drawing showing a sectional top view of an operating device according to an embodiment. Fig.3 is a schematic block diagram illustrating components of an operating device according to an embodiment. Fig.4 is a diagram schematically illustrating range spectra obtained for different positions of a hand by a radar sensor of an operating device according to an embodiment. Fig.5 is a flow diagram illustrating a method of estimating a presence of a hand on the handle of an operating device according to an embodiment. Fig.6 is a schematic drawing illustrating a presence signal obtained from range spectra for estimating the presence of a hand on the handle of an operating device according to an embodiment. DETAILED DESCRIPTION In the following, embodiments of the invention will be described in detail with reference to the accompanying drawings. It is to be understood that the following description of the embodiments is given only for the purpose of illustration and is not to be taken in a limiting sense. It should be noted that the drawings are to be regarded as being schematic representations only, and elements in the drawings are not necessarily to scale with each other. Rather, the representation of the various elements is chosen P 85022 INT - Kahler Käck Mollekopf - 85022int.Nachanmeldefassung.clean such that their function and general purpose become apparent to a person skilled in the art. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open- ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Fig.1 schematically illustrates an operating device 10 comprising a handle 11. Handle 11 has a predefined gripping position at which the user's hand is supposed to grip the handle 11. A hand 100 in the respective gripping position is schematically shown in Fig. 1. Operating device 10 includes a presence detector 15 that comprises a radar sensor 20. Radar sensor 20 may emit and detect radar waves within a spatial angle which defines a field of view (FOW) 21 of the radar sensor 20. Radar sensor 20 is mounted within the handle 11 such that the field of view 21 is covered by hand 100 when the hand grips the handle 11 in the predefined gripping position. Radar waves emitted and / or received by the radar sensor 20 may thus need to pass through the hand 100 if the hand is present and grips the handle 11, as shown in Fig.1. The radar sensor 20 provides a radar sensor signal that is used by the presence detector 15 to detect the presence of hand 100. The outer surface of the casing of handle 11 may thus not need to be pierced and modified for such presence detection, making it particularly robust and suitable for harsh environments, such as found in agricultural of construction vehicles. An area 12 of the handle that lies within the field of view 21 is bent. This is more clearly visible in Fig.2, which shows a cross-section through line A-A in Fig.1. The cross-section may in particular be a cross-section through a longitudinal axis along which the handle 11 extends. Field of view 21 generally covers a spatial angle and can thus also be seen in the cross-section of Fig.2. The hand 100 abuts against the bent area 12 throughout the field of view 21 of the radar sensor 20. Accordingly, within the field of view 21, the radar waves have to pass through the user's hand 100 at short range. In particular, the arrangement may be such that radar waves cannot pass past the user's hand 100, in other words all radar waves transmitted and received by radar sensor 20 may need to pass through the user's hand 100 and through the bent area 12 when the user's hand 100 grips the handle 11. This may allow a distinction between a user merely bringing an open hand close to the handle 11 and a user's hand fully gripping the handle 11. This will be explained in more detail further below. P 85022 INT - Kahler Käck Mollekopf - 85022int.Nachanmeldefassung.clean The radar sensor 20 may for example be arranged such that the field of view 21 passes through a bent area 12 that spans at least 15%, preferably at least 20% of the outer circumference of handle 11 in the cross-section of Fig.2. Fig.3 schematically illustrates a possible implementation of the presence detector 15 of the operating device 10. The radar sensor 20 may include a respective transmitter 22 and a receiver 23 for emitting and detecting radar waves, respectively. It may further comprise corresponding transmitting and receiving antennas and respective signal processing electronics. The presence detector 15 may further comprise a processing unit 30 that receives a radar sensor signal 25 from the radar sensor 20. Radar sensor signal 25 may include raw data, or may already include processed data, such as an inter- frequency signal, a range spectrum, or the like. Processing unit 30 may evaluate the received radar sensor signal 25 to estimate if the hand is gripping the handle 11. For example, it may derive a presence signal and may compare the presence signal to a threshold to estimate if the hand is present or not. It may further provide a presence indicator signal 35 to a function controller 40. The function controller 40 may in accordance with the presence indicator signal 35 activate and / or deactivate a function controlled by the operating device 10. For example, if the function controller 40 receives an indication that the hand 100 is gripping the handle 11, it may activate one or more control functions that are controlled by the handle 11. The operating device 10 may for example be a joystick, and function controller 40 may activate control functions operable by moving the handle back and forth, or sideways, such as driving functions of a vehicle, actuation of a tool of the machine, or the like. Function controller 40 may form part of the operating device 10, or may be provided separate therefrom (it may be optional). Preferably, the detection of the presence of the hand is based on a range spectrum, which may be generated by the radar sensor 20 and provided to the processing unit 30, or which may be generated by the processing unit 30 based on the received radar sensor signal 25. Radar sensor 20 may be a frequency-modulated continuous wave radar, and the generation of a range spectrum from such type of radar is generally known and will thus only be briefly explained herein below. The frequency of the radar wave emitted by sensor 20 may be modulated, using for example a saw-tooth modulation, so that chirped radar wave pulses may for example be emitted. The radar waves may be reflected by an object and detected by the receiver. A time delay between the transmitted and the received radar waves will result in a frequency difference due to the frequency modulation. The signal that is emitted may then be mixed with the signal that has been P 85022 INT - Kahler Käck Mollekopf - 85022int.Nachanmeldefassung.clean detected by the receiver, for example by multiplication, and the resulting multiplied signal has frequency components corresponding to a difference of the frequencies and to a sum of the frequencies. Low-pass filtering may then result in a so-called inter- frequency signal (also termed intermediate frequency signal) that is indicative of the frequency difference between the transmitted and the received radar wave signals. As the frequency difference is proportional to the time delay, and as the time delay is proportional to the distance of the radar sensor to the object, the frequency components of the inter-frequency signal are generally proportional to the distance. Presence of an object at a particular distance may thus result in a peak in the inter-frequency signal at the frequency which corresponds to the respective distance. Such inter-frequency signal may be further processed to provide a range spectrum, for example by transformation, calibration, normalization, A-to-D conversion, and the like. The signal may in particular be transformed into a frequency domain to obtain a spectrum (range spectrum) that indicates the signal levels at the different frequencies and thus at the different distances. Such range spectrum may be determined repeatedly from the inter-frequency signal. A range signal may thereby be obtained that includes one or more range spectra recorded over time. Note that such range spectra may include the signal power for different frequencies or may be calibrated to include the signal power for different distances. Fig.4 shows in the first diagram 61 a respective range spectrum in the frequency domain that has been calibrated and that shows the signal level for distances d between 0 and 7 m. On the vertical axis, the signal level, in particular the signal magnitude, is shown in units of dBFS (decibel relative to full scale). Range spectrum 60 of diagram 61 is obtained by the radar sensor 20 in handle 11 without presence of a hand within range. Generally, if an object is within range, a respective peak would appear in the range spectrum 60 at the respective distance of the object. As can be seen, the range spectrum 60 has a relatively large DC peak close to zero distance, in particular in the distance range up to 10 cm. It may thus be difficult to directly detect the presence of the hand based upon the range spectrum 60. Objects within range of the radar sensor, such as the walls of a vehicle cabin, a person in a vehicle, a seat and the like, may cause reflections of the emitted radar waves and may accordingly result in a (relatively large) background signal present in the range spectrum 60. In particular, such background may be present over most of the distance range of the range spectrum 60, as can be seen in diagram 61. The diagram 62 illustrates the range spectrum 60 for a situation in which a flat hand touches the surface of handle 11. It can be seen that the presence of the hand close to the P 85022 INT - Kahler Käck Mollekopf - 85022int.Nachanmeldefassung.clean handle 11 may not directly be recognized from the range spectrum 60. However, the magnitude of the range spectrum is slightly lower than the magnitude without presence of the hand shown in diagram 61. Diagram 63 of Fig.4 finally shows the range spectrum 60 for a situation in which the hand grips the handle 11, and in particular fully covers the field of view 21 of the radar sensor 20 and the bent portion 12 of the handle 11. Radar energy emitted by the radar sensor 20 may thus not escape on the sides of an object, such as the flat hand, that only touches the handle 11 without gripping it. Diagram 63 shows that the hand may be obscured by the DC peak of the range spectrum 60, but that the magnitude of the range spectrum 60 is significantly attenuated at larger distances. Accordingly, range spectrum 60 may be used to identify the presence of the hand that grips the handle 11, and may in particular be used to distinguish such gripping of the handle from the presence of other objects close to the handle 11. Processing unit 30 may accordingly evaluate a respective range spectrum 60 to detect the presence of the hand. It may in particular perform an evaluation of the energy in the spectral components at larger distances (i.e. at the respective frequencies) of the range spectrum. Such range spectrum may be derived from the radar signal and evaluated repeatedly during operation. An example of a method for detecting the presence of a hand is shown in the flow- diagram of Fig.5. Such method may for example be performed by the processing unit 30. In step S1, the range spectrum 60 is obtained. It may be obtained directly from the radar sensor 20, or may be determined, e.g. from raw data obtained from radar sensor 20 using any of the known ways or any of the ways described herein. The range spectrum may further be processed, for example by taking the absolute value of the range spectrum. In step S2, the range spectrum is summed over a predetermined frequency range or a predetermined distance range to determine a presence signal. For example, the magnitude of the range spectrum 60 above a minimum distance up to the maximum distance, or a sub-range of this range, may be summed. A minimum distance may for example be positioned at a distance larger than 0.2 m, for example at 0.3 or 0.4 m. It should be clear that other values may be chosen for the minimum distance above which summation of the range spectrum occurs. If plural radar sensors 20 are used, or if the radar sensor 20 comprises plural receivers and plural range spectra may be generated for the different receivers, then the summation may occur over each of the respective range spectra. The components of one, two, three or more receiver channels of the range P 85022 INT - Kahler Käck Mollekopf - 85022int.Nachanmeldefassung.clean spectrum may for example be summed over the predetermined distance range or the corresponding predetermined frequency range. By such summation, the influence of the relatively large DC peak in the range spectrum may be reduced. The minimum distance may in particular be chosen such that the DC peak is excluded from the summation. The sum may be a presence score, and such presence score may be obtained repeatedly for range spectra derived for subsequent portions of the radar signal or for range spectra subsequently received from the radar sensor. In other words, steps S1 and S2 may be performed repeatedly over time to obtain presence scores and thus a presence signal. The result of the summations, i.e. the presence scores, may form a presence signal 70, an example of which is shown in diagram 71 of Fig.6. The presence signal PS is shown over time t and the summation has been carried out to obtain larger positive values when no hand is present. The time plot 71 shows a situation in which no hand is present on the handle 11. In step S3, the presence signal 70 is compared to a presence threshold 80, which is likewise shown in Fig.6. In step S4, it is checked if the presence signal passes the threshold 80. If this is not the case, the method continues in step S1. As shown in the diagram 72 of Fig.6, if the user grips the handle at a point in time 75, the presence signal drops significantly as the user's hand attenuates and in particular absorbs the radar energy. This corresponds to the situation of diagram 63 of Fig.4 where the signal level of the range spectrum 60 drops significantly due to the user gripping the handle. The presence signal 70 passes the threshold 80, in particular drops below the threshold 80, which indicates the presence of the hand. Accordingly, in such situation, decision step S4 detects the passing of the threshold by the presence signal 70. It is thus determined in step S5 that the user's hand is present on the handle, in particular grips the handle. The threshold 80 may be tuned such that a gripping of the handle can be detected reliably while avoiding false-positives. As can be seen in Fig.6, which is data from an actual implementation example, the change in signal level of the presence signal 70 is quite steep when the handle is gripped, so that the threshold 80 may be easily set so that a reliable detection is achieved. In other implementations, the presence signal 70 may be determined differently, and the signal may for example rise above a respective threshold when the hand grips the handle 11. Further, it is also possible to dynamically determine the threshold 80, it may for example be adjusted in dependence on environmental P 85022 INT - Kahler Käck Mollekopf - 85022int.Nachanmeldefassung.clean parameters, such as temperature or the like. This is however usually not required, as the detection is quite stable against temperature fluctuations. In step S6, an indication of presence, such as the presence indicator signal 35, is provided to the function controller 40, which may in accordance therewith activate and / or deactivate a control function while the hand is present on the handle. Such activation and / or deactivation is however optional and may not form part of the method. By embodiments of the solution disclosed herein, it may thus become possible to more reliably detect the presence of the hand by using a radar sensor. As shown above, such detection may reliably distinguish between objects being close to the handle and the hand actually gripping the handle. A capacitive sensor may already detect the presence of a hand when the hand is only near the handle, whereas by such radar sensor detection, presence may only be detected if the handle is fully gripped. Further, the detection does not depend on whether or not the user wears a glove, which will be a hindrance for capacitive sensors. As other body parts, such as elbows, knees, and the like, cannot grip the handle but can only come near it, it may reliably be distinguished between such body parts and an actual gripping of the handle by the hand. This may not be achievable by capacitive sensors. Also, metallic objects may not trigger the detection of a hand, whereas a capacitive sensor may not be able to distinguish a hand from a metallic object. Detection reliability may thus be improved and false-positives may be reduced. While specific embodiments are disclosed herein, various changes and modifications can be made without departing from the scope of the invention. The present embodiments are to be considered in all respects as illustrative and non-restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein. P 85022 INT - Kahler Käck Mollekopf - 85022int.Nachanmeldefassung.clean List of reference signs 10 operating device 11 handle 12 bent area of handle 15 presence detector 20 radar sensor 21 field of view of radar sensor 22 radar wave transmitter 23 radar wave receiver 25 radar sensor signal 30 processing unit 35 presence indicator signal 40 function controller 60 range spectrum 61-63 diagrams 70 presence signal 71-72 diagrams 80 threshold PS presence signal S1-S6 method steps P 85022 INT - Kahler Käck Mollekopf - 85022int.Nachanmeldefassung.clean

Claims

AMENDED CLAIMS received by the International Bureau on 19 September 2025 (19.09.2025)CLAIMS:

1. An operating device for a machine, wherein the operating device (10) comprises a handle (11) configured to be gripped by a hand (100) of a user, wherein the operating device (10) comprises a presence detector (15) configured to detect a presence of the hand (100) on the handle (11), wherein the presence detector (15) comprises a radar sensor (20) providing a radar sensor signal, wherein the presence detector (15) is configured to estimate the presence of the hand (100) using the radar sensor signal, wherein the presence detector (15) is configured to estimate the presence of the hand (100) on the handle (11) based on an attenuation of a signal level of radar waves detected by the radar sensor (20) caused by the presence of the hand (100) on the handle ( 11).

2. The operating device according to claim 1, wherein the radar sensor (20) is mounted to the handle (11), preferably inside the handle (11).

3. The operating device according to claim 1 or 2, wherein the radar sensor (20) has a radiation angle and / or a detection angle for radar waves, wherein the handle (11) has a defined gripping position for the hand (100) of the user, wherein the radar sensor (20) is arranged on the handle (11) such that if the handle is gripped by the hand in the gripping position, the radiation angle and / or the detection angle is covered by the hand (100).

4. The operating device according to claim 3, wherein the handle comprises a gripping area (12) that is bent, the bent gripping area (12) being arranged to be coveredby the hand (100) of the user when the hand is in the gripping position, wherein the radar sensor (20) is arranged such that the bent gripping area (12) lies within the radiation angle and / or the detection angle of the radar sensor (20).

5. The operating device according to claim 4, wherein in a cross section through a longitudinal axis of handle, the bent area extends at least over 15%, preferably at least 20%, or at least 25% of a circumference of an outer surface of the handle.

6. The operating device according to any of the preceding claims, wherein the presence detector (15) is configured to generate a range spectrum (60) from the radar sensor signal, the range spectrum (60) indicating a signal level of detected radar waves for different distances from the radar sensor (20), wherein the presence of the hand (100) is estimated from the range spectrum.

7. The operating device according to claim 6, wherein the presence detector (15) is configured to estimate the presence of the hand (100) from the range spectrum (60) based on an attenuation of the signal level of detected radar waves at one or more distances in the range spectrum (60), preferably based on the attenuation of the signal level for distances larger than a minimum distance.

8. The operating device according to any of the preceding claims, wherein the presence detector (15) is configured to derive a presence signal (70) from the radar sensor signal, in particular from one or more range spectra (60), and to estimate the presence of the hand (100) from a value of the presence signal (70), preferably by comparing the presence signal to a presence threshold (80).

9. The operating device according to claim 8 when directly or indirectly dependent on claim 6, wherein the presence signal (70) is determined by summing the range spectrum (60) over a predetermined range of distances.

10. The operating device according to claim 8 or 9, wherein the presence detector is configured to compare the presence signal (70) to a predetermined threshold (80), wherein the presence detector (15) determines the hand (100) to be present on the handle (11) if the presence signal reaches or passes the predetermined threshold (80).

11. The operating device according to any of the preceding claims, wherein the operating device (10) is configured to activate one or more functions of the operatingelement if the presence detector (15) indicates the presence of the user’s hand (100) on the handle (11), wherein the one or more functions preferably comprise at least one of a function that is operable by an actuation of the handle (11), a function that is operable by an actuation of an operating element provided on the handle (11), a function that changes information displayed to the user, or a function that changes a graphical user interface provided for the user.

12. The operating device according to any of the preceding claims, wherein the radar sensor (20) employs a frequency -modulated continuous wave, FMCW, radar.

13. The operating device according to any of the preceding claims, wherein the radar sensor (20) comprises an integrated circuit that includes a radar transmitter (21) and a radar receiver (22), or a radar transceiver, wherein preferably, the radar sensor (20) comprises a monolithic microwave integrated circuit.

14. A method of estimating a presence of a hand of a user on an operating device, wherein the operating device (10) comprises a handle (11) that is configured to be gripped by the hand (100) of the user, wherein the operating device (10) comprises a presence detector (15) configured to detect a presence of the hand (100) on the handle (11), wherein the presence detector (15) comprises a radar sensor (20) providing a radar sensor signal, wherein the method comprises: obtaining a radar sensor signal generated by the radar sensor (20); and estimating the presence of the hand (100) using the radar sensor signal, wherein the presence detector (15) estimates the presence of the hand (100) on the handle (11) based on an attenuation of a signal level of radar waves detected by the radar sensor (20) caused by the presence of the hand (100) on the handle (11).[0001][0002]Statement under Article 19(1 ] PCT:[0003]Claims 1 -14 filed herewith replace the original claims 1 -14 of the present PCT application.[0004]Claims 1 -13 are unchanged.[0005]Claim 14 has been amended to adapt claim 14 to the original claim 1. Amended claim 14 contains the additional feature that: “the presence detector (15) estimates the presence of the hand ( 100) on the handle (11) based on an attenuation of a signal level of radar waves detected by the radar sensor (20) caused by the presence of the hand ( 100) on the handle ( 11)'[0006]Basis for the amendment is the original claim 1 . A further basis for the amendment is the last paragraph on page 5 of the original PCT specification.[0007]The amended method claim 14 fully corresponds to the original device claim 14. In the Written Opinion, it is indicated that the subject-matter of the original claim 1 is novel and inventive over the prior art.[0008]For the same reasons, the subject-matter of the corresponding amended claim 14 is novel and inventive over the prior art.

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