System and method for detecting contact between a first body part and a second body part

Abstract

The invention relates to a system for detecting contact between a first body part of a person and a second body part, comprising an electrical circuit, comprising a first electrode and a second electrode, each of which is electrically connected to a control device, and wherein the first electrode is in electrical contact with a first location on the person, and the second electrode is in electrical contact with a second location on the person, the second location being different from the first location, wherein the control device comprises a signal generator by means of which an alternating current or voltage signal can be applied across the electrodes, and a signal detector, and the signal detector comprises an impedance analyzer by means of which an electrical impedance between the first electrode and the second electrode can be measured. The first location and / or the second location is / are spaced apart from the body parts between which contact is formed. Furthermore, the invention relates to a method for detecting contact between body parts of a person.

Description

[0001] HANNKE BITTNER & PARTNER

[0002] PATENT AN WALTE RECHTSANWALTE

[0003] Prtifeninger StraBe 1

[0004] 93049 Regensburg

[0005] Max-Planck-Gesellschaft February 18, 2026 zur Fdrderung der Wissenschaften e.V. GAI01-061-WOPT Hofgartenstr. 8 HA / ME / sr D-80539 M unchen

[0006] System and method for detecting contact between a first body part and a second body part

[0007] Specification

[0008] The present invention relates to a device and method for detecting contact between a first part of a (for example, human) body and a second part of the same (for example, human) body. The first part of a body and the second part of the same body are also referred to herein as the first body part and the second body part.

[0009] Touch is of crucial importance in human communication, psychology, and disease transmission. It is also increasingly relevant to communication and interaction between humans and machines. There is therefore a need to detect touch. There are already a variety of devices and methods for detecting touch, but all known methods have disadvantages and, due to their complexity and the equipment required, are not suitable for being used by a person at all times in order to detect their touch with their own body over a long period of time.

[0010] Of particular importance are self-touches, i.e., contacts that occur when a person makes physical contact with another part of their own body with one (or both) of their hands, for example. Such self-touches can occur either directly on the skin or through clothing. Humans often perform self-touch with little or no awareness; these contacts can be an expression of the human’s psychological state, such as stress or concentration on a task. Self-touch of the face, which is characterized by discrete and brief gestures, is a particularly common human behavior, with people unconsciously touching their faces about 50 times per hour. Self-touch also serves communicative purposes, complementing facial expressions and verbal utterances. To understand the behavior of both individual humans and people in general, it isHANNKE BITTNER & PARTNER GAI01-061-WOPT

[0011] 2

[0012] necessary to reliably identify self-touch in humans. The measurement should be performed with as little equipment as possible to prevent the detection process from influencing the behavior; for example, wearing bulky equipment could cause the human to change their motions or avoid self-touch.

[0013] In addition, self-touch is an integral part of all sign languages, where many signs involve contact between the left and right hands or between one or both hands and the face or chest of the signer. Since many purely optical systems cannot recognize whether or not a particular gesture involves self-touch, recognizing gestures is often difficult and error-prone for such systems.

[0014] Recognizing self-touch using sensors could provide computational systems and machines with insights into the psychological states of a human and make their behavior easier to interpret. It would also provide a way to monitor hygiene and any potential risk of transmitting pathogens such as viruses. It could also make it easier for computational systems and machines to understand sign language. Sensing systems that can reliably detect self-touch could even enable humans to use self-touch as a channel of communication with machines, thus turning the surface of the human body (and / or the clothing worn) into an interface that enables communication with a machine that can recognize (self-) contact with this body surface (and, if necessary, assign it to specific information).

[0015] A human is able to reliably recognize the occurrence of self-touch through their own sense of touch. However, replicating this detection quality remains a challenge for external sensing systems, even though there are already a number of approaches to detecting self-touch.

[0016] Self-touch can be detected using electronic skin (e-skin). Such systems typically comprise thin, flexible, and stretchable electronic circuits that sense touch, temperature, or strain across an area. They are worn on the skin by a person and can then detect the location and / or force of a touch. One major disadvantage of these methods is that large areas of the body must be covered with electronic skin, which makes such a system more expensive and also limits its comfort and practicality for long-term use. Importantly, e-skin usually cannot differentiate between self-touches and touches caused by external contact. Furthermore, movement of the body may be confused with touch (motion artifacts).HANNKE BITTNER & PARTNER GAI01-061-WOPT 3

[0017] Optical systems in which hand posture and possible self-touch are reconstructed from RGB or RGB-D videos are also known. However, a particular problem with these systems is that the distance between the body parts that may be relevant for self-touch must be determined very precisely in order to be able to reliably distinguish between (self-) contact and the immediate proximity of these body parts. Depending on the viewing angle, reliable differentiation is often difficult. In addition, the quality of the data generated in this way depends on many factors, such as lighting conditions and clothing. For the analysis of everyday situations, continuous video recording from a distance that is large enough not to influence the behavior of the person being recorded, but small enough to ensure sufficiently accurate location resolution, is not realistic.

[0018] The invention is therefore based on the problem that it is technically difficult to non-invasively and reliably detect when skin-to-skin (or skin-to-clothing) contact within a single (human) body begins and ends. Existing approaches burden the wearer, alter their appearance, change the feel of the contact, do not work well in practical scenarios, and / or have difficulty determining the exact time of the beginning or end of contact. It is therefore the task of the present invention to provide a method and a system that can reliably detect self-touches without requiring an array of sensors directly in the contact area or one or more cameras observing the human. In addition, the system should be lightweight and compact to ensure that it can be used over long periods of time and encumbers the wearer as little as possible so that their behavior is not altered by the system.

[0019] This problem is solved by the subjects of the independent claims. Advantageous embodiments and further developments of the invention are the subject of the subclaims.

[0020] A solution to the problem is thus provided by a system according to claim 1.

[0021] Thus, the problem is solved by a system for detecting contact between a first body part of a person and a second body part of the same person. The system comprises an electrical circuit, comprising a first electrode and a second electrode, each of which is electrically connected to a control device. The first electrode is in electrical contact with a first location on the person. The second electrode is in electrical contact with a second location of the same person, the second location being different from the first location. The control deviceHANNKE BITTNER & PARTNER GAI01-061-WOPT

[0022] 4

[0023] comprises a signal generator by means of which an alternating current or voltage signal can be applied across the two electrodes. Furthermore, the system comprises a signal detector.

[0024] Unless otherwise specified, “electrodes” should be understood to mean a pair consisting of the first electrode and the second electrode.

[0025] Unless otherwise specified, “body parts” should be understood to mean a first body part of a person and a second body part of the same person, between which contact is to be detected. Such contact will also be referred to as self-touch in the following. It should be clarified that, prior to contact between the two body parts, it is not necessary to determine which body parts will actually make contact. Therefore, the two body parts are not specified. For instance, contact could be made between one hand and another as the first and second body parts. Similarly, contact could also be established between a finger and a nose, with the finger acting as the first body part and the nose as second body part. Depending on the body parts involved in the contact, a different impedance signal can be measured and preferably even used to identify the body parts involved.

[0026] Unless otherwise specified, “contact” should be understood to mean direct contact, e.g., skin-to-skin contact between the first body part and the second body part. Contact is also possible via conductive objects such as clothing. However, the contact arises in addition to the connection between the first body part and the second body part, which is mandatory because they are parts of the same body.

[0027] Preferably, the system comprises only two electrodes, namely the first electrode and the second electrode, which are in contact with the person. Thus, the system can be simple and causes little discomfort to the person wearing the only two electrodes.

[0028] An important feature of the system is that the location where the first electrode is attached and the location where the second electrode is attached are spaced apart from each other.

[0029] Furthermore, the first location and / or the second location is / are spaced apart from the first body part and the second body part. This makes it possible that at least one of the body parts does not need to be equipped with an electrode in order to detect contact between this and the other body part.HANNKE BITTNER & PARTNER GAI01-061-WOPT

[0030] - 5 -

[0031] The signal detector comprises an impedance analyzer by means of which an electrical impedance between the first electrode and the second electrode can be measured.

[0032] Such a system makes it possible to detect contact that occurs between two body parts of the person wearing the electrodes, where these two contacting body parts can be the same as or different from the locations at which the electrodes are positioned. Because no item needs to be placed at the contact location itself, the contact can occur naturally without being affected by measurement equipment.

[0033] In a preferred embodiment, no electrode is present at a contact location, where contact is formed between the first body part of the person and the second body part of the same person.

[0034] Contact detection is made possible by the fact that, when self-touch occurs in the area of the first body part and / or the second body part, a change in electrical impedance between the first electrode and the second electrode can be measured, since the tissue of the human body is electrically conductive. The impedance analyzer measures the electrical impedance between the two electrodes, which generally changes when a new contact occurs between two parts of the wearer’s body. Similarly, the electrical impedance between the two electrodes generally changes when an existing contact between two parts of the wearer’s body ends. These changes are particularly pronounced when the path from the first electrode through both of the contacting body parts to the second electrode has a distance that is shorter than the main conductive path that is always present from the first electrode through the body to the second electrode.

[0035] The chosen sensing principle preferably leverages the electrical conductivity of the human body to detect a contact. In general, the impedance (Z) between two points shows how strongly the intervening material opposes the flow of an alternating current (Z = V / l). Impedance is a complex number that comprises a real part R (usually known as resistance R) and an imaginary part X (usually known as reactance X). It thus consists of two frequency-dependent components, namely a magnitude |Z| = / ?2+ X2and phase angle ZZ = tan-1-. Bioimpedance, in turn, is the impedance of a biological medium. The resistance of a biological medium is mainly influenced by the total body water, which is moderately conductive, andHANNKE BITTNER & PARTNER GAI01-061-WOPT 6

[0036] the reactance is caused mainly by the organism’s cell membranes, which at least in some cases act like capacitors.

[0037] Preferably, the system comprises an evaluation device by means of which a voltage or current signal output by the impedance analyzer can be analyzed for a change in electrical impedance and by means of which a signal can be generated when a change in electrical impedance indicative of the start or end of contact between body parts is detected, for example when the change exceeds a threshold value within a time interval.

[0038] The evaluation device can be used to analyze the impedance signal measured by the impedance analyzer for relevant changes. To do this, the impedance signal is preferably monitored and / or recorded over a longer period of time, and changes over time are registered. When, within a time interval during this longer period, the electrical impedance changes in a manner that matches a predefined criterion, for example when its rate of change exceeds a reference value and / or when its magnitude decreases by more than another reference value, this indicates that at least one body part of the person fitted with the electrodes has come into contact with a second body part of the same person.

[0039] Preferably, data (sets) provided by the signal detector are processed (further) separately or together in order to detect the beginning and / or end of (skin-to-skin or skin-to-clothing) contacts that occur over time using the system or method. To this end, the system preferably uses, for example, signal-processing methods such as filtering, thresholding, and template matching and / or neural networks, without being limited to any of these embodiments. A neural network may, for example, comprise a recurrent neural network, a long-short-term memory network, and / or transformers that are trained by combining different input modalities such as video and / or audio, without being limited to the aforementioned embodiments.

[0040] Preferably, an electrical circuit applies an alternating signal (voltage or current) across the two electrodes and measures the resulting response signal (current and / or voltage). This response signal is preferably used to continually calculate the electrical impedance between the two electrodes. Since living tissue and also some types of clothing are conductive, the start of contact, e.g., the touching of two hands, leads to a drastic and rapid reduction in the magnitude of the measured impedance (also referred to herein as bioimpedance). Similarly, the end of contact leads to a significant increase in the magnitude of the bioimpedance. TheHANNKE BITTNER & PARTNER GAI01-061-WOPT

[0041] 7

[0042] system processes the measured signals to detect these changes and, in turn, determine the start and / or end of each self-touch that occurs.

[0043] Since changes in electrical impedance can be measured accurately, contact between a first body part and a second body part can be detected with a high degree of reliability, in particular when the bioimpedance of the conductive path through the contact has a value on the same order of magnitude as or smaller than the bioimpedance of the main conductive path that is always present from the first electrode through the body to the second electrode. The strength and / or pattern of the change can provide clues as to which body parts of the person made contact. Accordingly, the system is preferably designed and set up to analyze the determined bioimpedance values in detail, in particular in terms of time resolution and / or strength. Preferably, properties of the contact from these values could be derived from the bioimpedance values, for example, the body parts that come into contact and / or the size of the contact area.

[0044] In particular, the system can precisely record the start and end times of self-touches made by a human being or any other living organism. In order to detect self-contacts, two electrodes are attached to different parts of the same body, e.g., one electrode on each wrist. Accordingly, it is preferred that the two electrodes are attached to the same person.

[0045] Depending on the arrangement of the electrodes, the system can detect (skin-to-skin or skin-to-clothing) contact over most of a person's body, either in real time or offline in a previously recorded data set. Measuring the exact start and end of contact can, among many other applications, be used in particular to improve human-computer interaction, reconstruct human poses, and monitor human behavior.

[0046] In this context, “offline” can mean, for example, that a history of bioimpedance measured previously over a certain period of time is made available to the system at a later point in time, and the system uses this (historic) data to determine the beginning and end of contacts.

[0047] Preferably, the first electrode or the second electrode is grounded or set to another approximately constant reference voltage. Preferably the alternating current signal is an alternating current or voltage signal. It has proven to be particularly advantageous when the other of theHANNKE BITTNER & PARTNER GAI01-061-WOPT 8

[0048] first and second electrodes is ungrounded and the alternating current or voltage signal is applied to the ungrounded of the two electrodes.

[0049] Preferably, the electrodes are mechanically designed and manufactured in such a way that a conductive material can be brought into stable contact with the selected part of the human body or conductive object. Preferably, relative movement of the electrodes with respect to the body or object is minimized.

[0050] Preferably, an electrically conductive and externally insulated wire connects each electrode to the control device of the system, which may be designed as an electronic circuit board, for example.

[0051] In a preferred embodiment, the electrical circuit comprises at least one further electrical component having a selected impedance, wherein the at least one further electrical component is arranged in a signal path between the signal generator and the body and in electrical series with the body. Preferably, within a signal path from the signal generator to the body, at least one electrical component with a selected impedance is connected in series with the body (or bodies, or body and object) to create an impedance divider.

[0052] When the two electrodes are attached to the same body, an alternating current or voltage signal is applied to one electrode, and the other electrode is connected to ground or a reference voltage, the impedance divider effect creates a measurable voltage or current signal that depends on the impedance of the signal path through the body. This impedance changes when contact between body parts starts or ends as long as the contact provides a second conductive path for the alternating current to flow between the electrodes and through the body compared to the main path that is always present between the two electrodes through the body. The impedance change tends to be particularly large when the path distance from the first electrode through the contacting body parts to the second electrode is shorter than the main path distance from the first electrode through the body to the second electrode.

[0053] Preferably the electrical circuit comprises one or more analog signal filter circuits for measuring an alternating current or voltage signal and for generating a low-frequency representation of the amplitude and / or phase of the alternating current or voltage signal at one or moreHANNKE BITTNER & PARTNER GAI01-061-WOPT 9

[0054] frequencies. Preferably, these low-frequency representations are then sampled significantly below the Nyquist frequency of the alternating current or voltage signal in the impedance analyzer by one or more analog-to-digital converters, generating one or more data streams that can be used for contact detection.

[0055] Alternatively, the system can comprise a computing device and an analog-to-digital converter, wherein an alternating current or voltage signal can be sampled directly with the ana-log-to-digital converter, and its amplitude and / or phase can be calculated at one or more frequencies by the computing device.

[0056] The control device preferably comprises a signal filter. Preferably, the signal generator generates an alternating current or voltage signal with a specific frequency, a discrete set of frequencies, or a frequency range.

[0057] The present invention also relates to a method for detecting contact between a first body part and a second body part of the same person.

[0058] This method is preferably executable by a system as described above. Accordingly, all features disclosed for the system shall also be deemed to be disclosed for the method.

[0059] Similarly, the system described above is designed and configured to execute a method or parts thereof as described below. Accordingly, all features disclosed for the method shall also be deemed to be disclosed for the system.

[0060] In the method according to the invention, detecting contact between the first body part and the second body part of the same person is achieved by the following steps:

[0061] forming an electrical circuit comprising a first electrode, a second electrode, and a control device, wherein the first electrode is placed in electrical contact with a first location on the person (20), the second electrode is placed on a second location on the same person, and the first location and the second location are spaced apart from each other, generating an alternating current or voltage signal by a signal generator of the control device,

[0062] applying the alternating current or voltage signal across the two electrodes, andHANNKE BITTNER & PARTNER GAI01-061-WOPT

[0063] 10

[0064] measuring an electrical impedance between the first electrode and the second electrode by means of an impedance analyzer of the signal detector.

[0065] This method is relatively easy to perform and requires only a minimal operational setup. It requires only two electrodes and has the great advantage that no electrodes need to be placed on the body parts where contact is to be detected. This means that these body parts can remain free, and the person can use them without hindrance, without being impeded by electrodes placed there. This is particularly advantageous when contacts of one or both hands are to be detected. Since the hands, and especially the fingertips, are particularly sensitive, electrodes placed there are perceived as particularly disturbing. In addition, electrodes placed there often distract the person, so that observation of involuntary contacts would not be possible or would only be possible to a limited extent.

[0066] Preferably, the first electrode and / or the second electrode are placed independently from each other on a location selected from a group comprising a wrist, a shoulder, an arm, a back of a hand, a bridge of a nose, and a back of a neck. It has been shown that placing an electrode at one of these locations is perceived as particularly unobtrusive. Placing an electrode on a wrist or a back of a hand has proven to be particularly advantageous, as a large number of contacts are made with the hands and, with an electrode at one of the aforementioned body locations, a particularly large change in bioimpedance can be detected when the hand in proximity to the electrode makes contact.

[0067] As explained above, a major advantage of the method is that electrodes do not necessarily have to be placed on the parts of the body where contact is to be detected. In principle, it would of course be possible to measure a change in bioimpedance when contact is made with a part of the body that is equipped with an electrode. For example, a hand not equipped with an electrode could touch a shoulder equipped with a first electrode, and a change in bioimpedance could be detected using a second electrode placed on the wrist of the hand that is touching the shoulder. However, it is preferable to place both electrodes so that they interfere with the user as little as possible and can also be covered by clothing.

[0068] In a preferred variant of the method, an electrical impedance is measured between the first electrode and the second electrode. The measured electrical impedance depends on the interaction between a known impedance and an unknown and time-varying electrode-to-HANNKE BITTNER & PARTNER GAI01-061-WOPT

[0069] 11

[0070] electrode electrical impedance of the body of the person, which are in electrical series within the circuit. Changes in the measured impedance reflect changes in the electrode-to-electrode impedance of the body, which occur when contact between body parts starts or ends.

[0071] Preferably, a size of the contact area and / or the body parts in contact are inferred based on a detailed analysis of the measured impedance. It has been shown that a detailed analysis of the measured impedance signal can provide information about the contact surface over which the contact takes place and / or which parts of the body are involved in the contact. To accomplish this, it is conceivable to analyze the impedance signal curve at different frequencies. One frequency range in which a particularly large difference in the measured impedance occurs during contact is the range from 1 kHz to 10 MHz, preferably 10 kHz to 7.5 MHz, more preferably 100 kHz to 5 MHz, most preferably 200 kHz to 4.5 MHz. However, other ranges may also provide clues as to which body parts are involved in the contact and how much they are touching one another.

[0072] In a preferred variant, the method allows for determining a pose of a person (20) by: capturing an image of the person in contact with the first electrode by means of an optical sensor, preferably a camera, in particular preferably an RGB camera,

[0073] calculating an approximate pose of the person from the image, and

[0074] determining a more precise pose of the person based on the approximate pose of the person by including information obtained through a method as described above about a detected contact between a first body part of the person and another body part of the same person.

[0075] This variant of the method makes it possible to recognize poses that are supposedly recognized from images with even greater certainty. In particular, if it is not possible to determine from the images whether there is actually contact between two body parts, for example due to the angle of the camera, this variant of the method can provide an indication of such contact and thus also of the pose actually assumed by the person. This variant of the method thus provides information about the arrangement of body parts in relation to each other, which cannot be deduced from image information, especially in the case of a 2D image from an RGB camera.

[0076] Further advantages and embodiments are apparent from the accompanying figures.HANNKE BITTNER & PARTNER GAI01-061-WOPT

[0077] 12

[0078] The figures show:

[0079] Fig. 1 a schematic illustration of a sensing principle of the system;

[0080] Fig. 2 a schematic representation of current pathways for different poses;

[0081] Fig. 3 an illustration of a wrist-to-wrist bioimpedance measured for the poses illustrated in Fig. 2; and

[0082] Fig. 4 a schematic representation of the electrical circuit of an embodiment of the present invention.

[0083] Fig. 1 illustrates schematically a sensing principle of the system 100. In the illustrated embodiment, the first electrode 11 and the second electrode 12 are each placed on one of the person's 20 wrists 21 and 22. The bioimpedance of the person’s body 20 is measured from wrist 21 to wrist 22. Accordingly, in the no-touch pose N shown on the left, where the hands 31, 32 do not touch each other, the impedance is influenced exclusively by an electrical pathway Puthat encompasses both arms 41, 42 and the torso 25 of the person (across their shoulders 51, 52, and neck 54). The measured bioimpedance is referred to as Zu(t).

[0084] Forming a new electrical pathway Pcbetween the wrists 21, 22, such as when the hands 31 and 32 contact each other, is represented as an additional bioimpedance component Zc(t) in parallel with the original bioimpedance Zu(t), as shown on the right.

[0085] The bioimpedance measured between two anatomical locations (such as the wrists 21, 22) varies significantly between people because it depends on the shape and composition of their bodies. It even varies within one person over time because of, for example, changes in skin temperature, core temperature, body position, muscle contraction, exercise, hydration, and fasting state.

[0086] However, as shown in Fig. 1, bringing two distinct body parts (like hands 31, 32) into contact establishes a new electrical pathway Pcthrough which current can flow in parallel with the default pathway Puthrough the body 20. Any new electrical pathway Pcleads to a decreaseHANNKE BITTNER & PARTNER GAI01-061-WOPT

[0087] 13

[0088] in the total bioimpedance Ztotai following the formula Ztot

[0089]

[0090] wherein Zuis the bioim- \ZUzc)

[0091] pedance of the default pathway (Pubetween the wrists along the arms 41, 42 and the torso 25) and Zcis the bioimpedance of the newly established pathway Pcformed by the new contact (between the wrists 21 , 22 along the hands 31 , 32).

[0092] Figure 2 shows a schematic presentation of current pathways Puand Pcfor different poses. For all six poses, their different conductivity topologies are illustrated in dashed lines. The pose on the upper left (indicated with “N”) illustrates a so-called no-touch pose. The electrical pathway Puillustrated for this pose through the user’s arms 41 , 42 and across their shoulders 51, 52 is present in all poses.

[0093] Four of the other illustrated poses provide an additional electrical pathway Pc:

[0094] Touching the fingertips of the left hand 31 and the right hand 32 together (tLR4) provides an additional electrical pathway Pcthrough the fingertips;

[0095] Touching the entire left and right hands 31, 32 together (tLR) provides an additional electrical pathway through the hands 31 , 32;

[0096] Touching the face 26 with the left hand 31 and the right hand 32 (tFLR4) provides an additional electrical pathway through the hands 31, 32 and the face 26; and

[0097] Touching the face 26 only with the right hand 32 (tFR4) provides an additional electrical pathway through the right hand 32, the face 26, the neck 54, and the left arm.

[0098] Performing a hand gesture like clenching the left hand 31 and the right hand 32 (cLR) does not alter the circuit topology but might also alter the (baseline) impedance Zu.

[0099] Fig. 3 illustrates the wrist-to-wrist bioimpedance Ztotai measured for the poses illustrated in Fig. 2. The solid lines illustrate the measured bioimpedance Ztotai for the poses tLR4, tLR, tFLR4, tFR4, cLR, and the dashed lines their respective baselines Zu(for pose N). The magnitude and phase were measured from 100 Hz to 5.1 MHz, but only the measured magnitude is illustrated in Fig. 3. The insets in the magnitude plot zoom in to show the responses from 200 kHz to 4.5 MHz.

[0100] As illustrated in Fig. 3, it is possible to notice substantial differences between the bioimpedance magnitudes across poses, especially at high frequencies from 200 kHz to 4.5 MHz as illustrated in the insets in Fig. 3. The baselines Zu(correlating to pose N) are also relativelyHANNKE BITTNER & PARTNER GAI01-061-WOPT

[0101] - 14 -

[0102] stable in this range, indicating that the change of the bioimpedance (A Bioimpedance) depends mainly on the respective pose itself.

[0103] Fig. 4 is a schematic representation of the electrical circuit 80 of an embodiment of the present invention. As illustrated, the system 100 comprises only two electrodes 11 and 12, which are in contact with the person 20 whose self-contacts are to be detected.

[0104] The signal generator 60 and the signal detector 70 are in the same electric circuit 80. Preferably, the signal generator 60 and the signal detector 70 form a common unit. At most one of the electrodes 12 is grounded or set to another (approximately) constant reference voltage. The other electrode 11 is ungrounded. The signal detector is in direct electric contact with the (single) ungrounded electrode 11.

[0105] The electrical circuit 80 has a known electrical impedance illustrated with reference sign 82. Since the electrical impedance 82 of the electrical circuit 80 is known, the electrical impedance Ztotai of the person could be measured.

[0106] In case no additional electric pathway Pcis established by a contact of the first body part 31 of the person 20 and another body part 32, the pathway Pcis not conductive (indicated by open switch 30), and the contact bioimpedance Zcfor this path is infinitely high. Consequently, only the baseline bioimpedance Zuis measured. However, if the person 20 assumes a pose in which additional contact is formed between the first body part 31 and the additional body part 32 (i.e. , symbolically closing the switch 30), the path Pcbecomes conductive, and the impedance Ztotai measured at the electrode changes according to the formula Ztotai=

[0107]

[0108] The applicant reserves the right to claim all features disclosed in the application documents as essential to the invention, provided that they are novel in relation to the prior art, either individually or in combination. It should also be noted that the individual figures also describe features which may be advantageous in themselves. The skilled person will immediately recognize that a particular feature described in a figure may be advantageous even without adopting other features from that figure. Furthermore, the skilled person will recognize thatHANNKE BITTNER & PARTNER GAI01-061-WOPT

[0109] - 15 -

[0110] advantages may also result from a combination of several features shown in individual or different figures.HANNKE BITTNER & PARTNER GAI01-061-WOPT

[0111] - 16 -

[0112] List of reference signs

[0113] 11 first electrode

[0114] 12 second electrode

[0115] 20 person, body

[0116] 21, 22 wrist, first location, second location

[0117] 25 torso

[0118] 26 face, first body part, second body part

[0119] 30 switch

[0120] 31 left hand, first body part, second body part

[0121] 32 right hand, first body part, second body part

[0122] 41 , 42 arm

[0123] 51, 52 shoulder

[0124] 54 neck

[0125] 60 signal generator, control device

[0126] 70 signal detector, impedance analyzer

[0127] 80 electrical circuit

[0128] 82 (known) electrical impedance (of the electrical circuit 80)

[0129] 100 system

[0130] Zu(t), Zu(baseline) bioimpedance (of (default) pathway Pu)

[0131] Zc(t) Zc(contact) bioimpedance (of (newly established) pathway Pc)

[0132] Ztotai measured bioimpedance (of the person)

[0133] N no-touch pose

[0134] tLR4 pose of touching the fingertips of the left hand and the right hand together tLR pose of touching the entire left and right hand together

[0135] tFLR4 pose of touching the face with the left hand and the right hand

[0136] tFR4 pose of touching the face only with the right hand

[0137] cLR pose of performing a hand gesture like clenching the left hand and the right hand Pc(electrical) pathway (closed by establishing contact)

[0138] Pu(electrical) baseline pathway / default pathway

Claims

HANNKE BITTNER & PARTNER GAI01-061-WOPT- 17 -System and method for detecting contact between a first body part and a second body partClaims1. A system (100) for detecting contact between a first body part (31) of a person (20) and a second body part (26, 32) of the same person (20) comprising an electrical circuit (80), comprising a first electrode (11) and a second electrode (12), each of which is electrically connected to a control device, and wherein the first electrode (11) is in electrical contact with a first location on the person (20), wherein the second electrode (12) is in electrical contact with a second location of the same person (20), the second location being different from the first location, wherein the control device comprises a signal generator (60) by means of which an alternating current or voltage signal can be applied across the two electrodes (11, 12), and a signal detector (70), comprising an impedance analyzer by means of which an electrical impedance (Ztotai) between the first electrode (11) and the second electrode (12) can be measured, characterized in thatthe first location and / or the second location is / are spaced apart from the first body part (31) and the second body part (26, 32) between which contact is formed.

2. The system (100) according to claim 1,characterized byan evaluation device by means of which an impedance signal output from the impedance analyzer can be analyzed for a change in electrical impedance and by means of which a signal can be generated if the change in electrical impedance exceeds a threshold value within a time interval.

3. The system (100) according to one of the previous claims,characterized in thatan alternating current or voltage signal is applied to one of the electrodes (11) while the other electrode (12) is connected to ground or a reference voltage.

4. The system (100) according to one of the previous claims,characterized in thatHANNKE BITTNER & PARTNER GAI01-061-WOPT18the electrical circuit (80) comprises at least one further electrical component having a selected impedance (82), wherein the at least one further electrical component is arranged in a signal path between the signal generator (60) and the body (20) and in electrical series with the body (20).

5. The system (100) according to one of the previous claims,characterized in thatthe electrical circuit (80) comprises one or more analog signal filter circuits for measuring an alternating current or voltage signal and for generating a low-frequency representation of the amplitude and / or phase of the alternating current or voltage signal at one or more frequencies, ora computing device and an analog-to-digital converter, wherein an alternating current or voltage signal can be sampled directly with the analog-to-digital converter and its amplitude and / or phase can be calculated at one or more frequencies by the computing device.

6. The system (100) according to one of the previous claims,characterized in thatno electrode is located at a contact location, where contact is formed between the first body part (31) of the person (20) and the second body part (26, 32) of the same person (20).

7. The system according to claim 1,characterized in thatthe signal generator (60) and the signal detector (70) are both elements of the control device and are preferably located in the same housing.

8. The system (100) according to one of the previous claims,characterized in thatthe electrical impedance (Ztotai) between the first electrode (11) and the second electrode (12) is lower when there is direct contact between the first body part (31) of the person (20) and the other body part (26, 32) of the same person (20) than when there is no direct contact between the first body part (31) of the person (20) and the otherHANNKE BITTNER & PARTNER GAI01-061-WOPT19body part (26, 32) of the same person (20).

9. The system (100) according to one of the previous claims,characterized byan optical sensor that is capable of capturing an image of the person (20) in contact with the first electrode (11), wherein the optical sensor is preferably a camera, in particular preferably an RGB camera, andan analysis device that is in data communication with the optical sensor, wherein the analysis device is capable of estimating the pose of a person captured by the optical sensor from the data captured by the optical sensor or from data derived therefrom.

10. The system (100) according to claim 9,characterized in thatthe analysis device is in data communication with the impedance analyzer, wherein the analysis device is capable of increasing the accuracy of the determined pose of the person (20) by incorporating data from the impedance analyzer.

11. Method for detecting contact between a first body part (31) of a person (20) and a second body part (26, 32) of the same person (20),characterized by the step offorming an electrical circuit (80) comprising a first electrode (11), a second electrode (12), and a control device, wherein the first electrode (11) is placed in electrical contact with a first location on the person (20), the second electrode (12) is placed on a second location (21, 22) on the same person (20) as the first body part (31), wherein the first location (31) and the second location (21, 22) are spaced apart from each other, wherein the first location and / or the second location is / are spaced apart from the first body part (31) and the second body part (26, 32),generating an alternating current or voltage signal by a signal generator (60) of the control device,applying the alternating current or voltage signal to at least one of the electrodes (11, 12), andmeasuring an electrical impedance (Ztotai) between the first electrode (11) and the second electrode (12) by means of an impedance analyzer (70) of the signal detectorHANNKE BITTNER & PARTNER GAI01-061-WOPT20(70).

12. Method according to claim 11,characterized in thatthe first electrode (11) and / or the second electrode (12) are independently from each other placed on a location (21, 22) selected from a group comprising a wrist (21, 22), a shoulder (51, 52), an arm (41, 42), a bridge of a nose (26), and a back of a neck (54), wherein preferably the first electrode (11) and the second electrode (12) are placed on different locations (21, 22), wherein preferably a conductive path exists between the two electrode locations (21 , 22) that passes through the first body part (31) of the person (20) and across a contact point to the second body part (26, 32) of the same person (20), where the contact is to be detected.

13. Method according to claims 11 or 12,characterized in thatthe electrical impedance measured between the first electrode (11) and the second electrode (12) depends on the interaction between a known impedance (82) and an unknown and time-varying electrode-to-electrode electrical impedance (Ztotai) of the body of the person (20), which are in electrical series within the circuit.

14. Method according to any of claims 11 - 13,characterized in thata size of the contact area and / or the body parts (26, 31 , 32) in contact are inferred based on a detailed analysis of the measured impedance (Ztotai).

15. Method for determining a pose of a person (20) by:capturing an image of the person (20) in contact with the first electrode (11) by means of an optical sensor, preferably a camera, in particular preferably an RGB camera, calculating an approximate pose of the person (20) from the image, and determining a more precise pose of the person (20) based on the approximate pose of the person (20) by including information obtained through a method according to any of claims 11 - 14 about a detected contact between a first body part (31) of the person (20) and another body part (26, 32) of the same person (20).

Images