TDR-based system for hand or body part positioning detection on objects, in particular on steering wheels

Abstract

A sensor system (10) for position detection of a hand or body part on an object, in particular on a rim (40) of a steering wheel (38), comprises at least one electrically conductive signal line (12) which can be arranged on a surface of the object, with prior knowledge of a relationship between a distance of any portion of the at least one signal line (12) from a reference point and information about a position on the object, a signal voltage source (26) for providing a time-dependent measurement signal which will travel along the signal line (12), and a control and evaluation unit (28). From the received reflected measurement signal, the control and evaluation unit (28) determines (54) one or more positions on the object of one or more portions of the at least partially reflected measurement signal of the signal line (12). Based on the determined one or more positions, the control and evaluation unit (28) determines (56, 62, 64) a position of the hand or body part on the object.

Description

Technical Field

[0001] The present invention relates to: a sensing system for detecting the location of a hand or other body part on an object (particularly a steering wheel); an orientation of the sensing system for detecting the location of a hand or body part; a method for detecting the location of a hand or body part by operating the sensing system; and a software module for automatically performing the method. Background Technology

[0002] In the field of motor vehicle sensor applications, it is known to use sensors in so-called Hands-Off Detection (HOD) systems, where one or more sensors provide information about whether the driver has their hands on the vehicle's steering wheel. This information can be provided as input to Advanced Driver Assistance Systems (ADAS), such as Adaptive Cruise Control (ACC), which can warn and remind the driver to take control of the steering wheel again based on the provided sensor signals. In particular, such HOD systems can be used to support compliance with the Vienna Convention requirement that the driver must always maintain control of the vehicle. HOD systems can also be used in parking assistance systems or configured to assess driver activity at high speeds in ADAS.

[0003] It is also known that capacitive sensors are used in vehicle HOD systems.

[0004] For example, WO 2016 / 096815 A1 discloses a planar flexible carrier for steering wheel heating and / or sensing the presence of a driver's hands on the steering wheel. The planar carrier, which can be mounted on a steering wheel rim without wrinkles, comprises a portion of a generally rectangular planar flexible foil having two longitudinal sides and two transverse sides. The length B of the side is 0.96 to 1.00 times the rim circumference. N slits per unit length are provided on each longitudinal side, wherein the slits on one side are staggered relative to opposite slit portions on the opposite side. The determination of the optimal shape and size of the slits is described. Further described are the heat carrier, heating and / or sensing devices, and methods for their manufacture.

[0005] Multi-zone HOD capacitive sensor systems are known in the art, comprising multiple distinct and independent sensing areas along the steering wheel. These HOD capacitive sensor systems are capable of distinguishing various ways in which a driver holds the vehicle's steering wheel (one hand, two hands, angular position).

[0006] For example, European Patent EP 1 292 485 B1 describes a steering wheel for a vehicle, comprising a steering ring, a hub, and at least one spoke connecting the steering ring and the hub. On the steering ring, sensors are arranged in a distributed manner along the circumference of the steering ring, extending over its entire length. The sensors can be configured to operate on a resistive, capacitive, or inductive basis. The sensors are subdivided into multiple segments arranged one after another in the longitudinal direction of the steering ring. The spacing between two sensor segments in the longitudinal direction of the steering ring is less than the width of a finger, wherein the sensor segments in the longitudinal direction of the steering ring are less than the width of a finger. Thus, the thumb and fingers of the hand can be reliably distinguished from each other, achieving high spatial resolution.

[0007] The use of other sensors has also been proposed for HOD applications. WO 2019 / 086388 A1 describes a system for detecting whether a user's at least one hand is on the steering wheel. This system is typically based on time-domain reflectometry (TDR) measurements. The system includes a signal line extending from a first point to a second point and disposed along at least a portion of the surface of the steering wheel. The system also includes a detection unit coupled to the first point. The detection unit is configured to send a time-correlated detection signal traveling along the signal line to receive a reflected signal traveling along the signal line and to detect the presence of a hand on the surface based on the reflected signal.

[0008] Purpose of the invention

[0009] Therefore, one object of the present invention is to provide a low-complexity sensing system for locating and detecting a hand or body part on an object (particularly a vehicle steering wheel), which is capable of distinguishing at least one hand or body part in contact with the object, no hand or body part in contact with the steering wheel, and at least one hand gripping the object.

[0010] This objective is achieved by the system for detecting a hand or body part on an object (particularly on a steering wheel) according to claim 1, the steering wheel with hand or body part positioning detection according to claim 9, and the method for detecting hand positioning on an object (particularly on a steering wheel) according to claim 10. Summary of the Invention

[0011] In one aspect of the invention, this objective is achieved by a sensing system for detecting the positioning of a hand or body part on an object (particularly on a steering wheel rim), the sensing system comprising at least one conductive signal line, a signal voltage source, and a control and evaluation unit.

[0012] At least one conductive signal line may be arranged to extend along a portion of the surface of an object, having prior knowledge of the relationship between the distance of any portion of the at least one signal line from a reference point and information about its position on the object.

[0013] The signal voltage source can be connected to each signal line and is configured to provide a time-dependent measurement signal to travel along the correspondingly connected signal line.

[0014] The control and evaluation unit can be operationally connected to each signal line and configured for use

[0015] - The measurement signal is received after at least a portion of the measurement signal has been reflected by the signal line.

[0016] - Determine one or more locations on an object where at least part of the signal line reflects the measurement signal.

[0017] - Determine the location of a hand or body part on an object based on one or more determined positions of one or more portions of a signal line.

[0018] The term "signal" as used throughout this application shall be understood to mean an electrical or electromagnetic signal. The phrase "configured as" as used in this application shall be specifically understood to mean specifically programmed, laid out, installed, or arranged. The term "(electrical) connection" as used in this application shall be specifically understood to mean an electrical connection made by means of current connection or capacitive or inductive coupling.

[0019] Generally, the sensing system for locating and detecting hand or body parts according to the present invention is based on a time-domain reflectometer (TDR), and the provided time-correlated measurement signal, intended to travel along the correspondingly connected signal lines, is suitable for TDR measurement. The signal shape of the time-correlated measurement signal may vary depending on the specific application.

[0020] The provided time-correlated measurement signal will travel along the correspondingly connected signal line and will be reflected at least partially from any impedance discontinuity along the signal line. Such impedance discontinuity can be temporarily generated by a hand or one or more fingers of the hand or body part positioned near the signal line. The nature of the resulting single or multiple impedance discontinuities is determined by the nature of the hand or body part positioned on the object.

[0021] With prior knowledge of the relationship between the distance of any portion of at least one signal line from a reference point and information about the position on the object, the proposed sensing system is able to determine the location of detected impedance discontinuities on the object. This information can be used to determine hand or body part positioning scenarios on the object, such as one or both hands touching or gripping an object like a steering wheel. The proposed sensing system for detecting hand or body part positioning on an object can have low complexity and is at least able to distinguish between scenarios where at least one hand or body part is in contact with the object, where no hand or body part is in contact with the object, and where at least one hand is gripping an object like a steering wheel.

[0022] Preferably, each signal line is designed to have a predefined uniform characteristic impedance. In this way, impedance discontinuities caused by the touch or grip of the steering wheel operator's hands are more prominent than any other potential impedance interference.

[0023] Preferably, the proposed sensing system is intended for the location detection of a hand or body part on an object formed by and part of a motor vehicle steering wheel. The term "motor vehicle" as used in this patent application should be specifically understood to include passenger cars, trucks, semi-trailer trucks, and buses, although application to other vehicles such as aircraft (yoke) or ships is also contemplated within the scope of this patent application. Furthermore, the proposed sensing system can be used for the location detection of a hand or body part on the steering mechanism of engineering vehicles or agricultural vehicles, etc.

[0024] According to the present invention, the at least one signal line includes: a first portion arranged to extend along a portion of the surface of the rim of the steering wheel facing the steering wheel operator; and a second portion arranged to extend along a portion of the surface of the rim of the steering wheel facing away from the steering wheel operator, wherein the first portion and the second portion are electrically connected in series.

[0025] It should be further noted that the terms “first,” “second,” etc., used in this application are for distinguishing purposes only and do not imply any indication or expectation of order or priority.

[0026] Using this configuration, touching only one surface of the steering wheel rim with a hand or other body part will create an impedance discontinuity, resulting in a reflected signal only in the first or second portion of the signal line. The steering wheel operator's grip will produce two reflections of the measurement signal supplied to the signal line at the same location on the rim. The two reflections of the measurement signal supplied to the signal line detected at different locations on the rim can be attributed to both hands contacting the steering wheel. Thus, a reliable distinction can be made between the location of one or more of the steering wheel operator's hands and the location of one or more grips in a particularly simple manner.

[0027] Furthermore, in such embodiments, at least one signal line is preferably shaped into a zigzag pattern, such that the maximum lateral dimension between adjacent turning points of the zigzag pattern is greater than 25% and less than 50% of the circumference of the steering wheel rim's cross-section. In this way, a first portion of the signal line is easily arranged to extend along the main portion of the rim's surface facing the steering wheel operator, and a second portion of the signal line is easily arranged to extend along the main portion of the rim's surface facing away from the steering wheel operator. It should be appreciated that, by using a zigzag pattern for the signal line, the total length of the signal line, which can be arranged to extend along a portion of the steering wheel rim's surface, can be increased compared to a straight shape, thereby alleviating the requirements regarding time resolution. Furthermore, using a zigzag pattern makes it easier to cover most of the steering wheel rim's surface, thus avoiding any "dead zones," i.e., areas where the sensing system might not be able to detect the steering wheel operator's hand touching or even gripping the rim.

[0028] Preferably, the zigzag pattern comprises semi-circular turns connected by straight sections. This provides a suitable signal line that is simple to design and requires minimal manufacturing effort.

[0029] In a preferred embodiment of the sensing system, at least one signal line is designed as a microstrip line or a coplanar waveguide, either of which includes a flexible dielectric carrier. Microstrip lines and coplanar waveguides are well-known solutions for designing electrical transmission lines as signal lines with a well-defined, desired uniform impedance. A flexible dielectric carrier advantageously allows the signal line to be mounted on the surface of a steering wheel rim with minimal wrinkling and almost imperceptible to the steering wheel operator.

[0030] Preferably, at least one signal line is terminated by at least one lumped impedance equal to the characteristic impedance of the signal line. In this way, reflection of the measurement signal provided at one end of the signal line can be avoided, and reflections are not superimposed on impedance discontinuities caused by the touch or grip of the steering wheel operator's hand.

[0031] The time-correlated measurement signal does not need to be the pulse signal commonly used in TDRs, but can be a continuous signal. In a preferred embodiment of the sensing system, the signal voltage source is configured to provide a pulse-shaping signal, a frequency-scanning signal, a pseudo-random phase-shift keying signal, or a pseudo-random signal. This provides design freedom to appropriately cover a wide range of applications.

[0032] In the case of a swept-frequency sine wave, the control and evaluation unit can be configured to apply a Fast Fourier Transform (FFT) to the received reflected measurement signal. In the case of a pseudo-random phase-shift keying signal or a pseudo-random signal, the control and evaluation unit can be configured to apply cross-correlation between the provided measurement signal and the received reflected measurement signal.

[0033] In another aspect of the invention, a steering wheel with hand or body part positioning detection is provided. The steering wheel includes embodiments of a sensing system for hand or body part positioning detection as disclosed herein, wherein at least one conductive signal line is arranged to extend along a portion of the surface of the steering wheel rim. The benefits described in the context of the sensing system according to the invention fully apply to the proposed steering wheel.

[0034] In particular, the proposed steering wheel is advantageously suited for use in the automotive field; that is, in vehicles. However, within the scope of the invention, it is also contemplated for use in aircraft and marine vessels.

[0035] In another aspect of the invention, a method is provided for detecting the location of a hand or body part on an object (particularly on a steering wheel rim) by means of an operative sensing system, wherein the sensing system comprises: at least one conductive signal line arranged to extend along a portion of the surface of the object, wherein it has prior knowledge of the relationship between the distance of any portion of the at least one signal line from a reference point and information about the position on the object; a signal voltage source operatively connectable to each signal line; and a control and evaluation unit operatively connectable to each signal line.

[0036] The method includes at least the following steps:

[0037] - By operating a signal voltage source, a time-dependent measurement signal is provided to the signal line, designed to travel along the correspondingly connected signal line.

[0038] - The operation control and evaluation unit receives the measurement signal after at least a portion of the measurement signal has been reflected by the signal line.

[0039] - The operation control and evaluation unit determines one or more locations on the object where one or more portions of the signal line have at least partially reflected the measurement signal, and

[0040] - The operation control and evaluation unit determines the location of a hand or body part on an object based on one or more determined positions of one or more portions of a signal line.

[0041] The benefits described in the context of the sensing system according to the invention apply fully to the proposed method.

[0042] In a preferred embodiment of the method, the step of determining the location of a hand or body part on an object includes: if only one location of a measurement signal that has been at least partially reflected on the rim has been determined, then determining the location of a hand or body part equivalent to single-touch positioning.

[0043] In a preferred embodiment of the method, if at least two locations on the object that at least partially reflect the measurement signal have been determined, the step of determining the location of a hand or body part on the object includes...

[0044] - Compare a first determined position on an object where at least a portion of the measurement signal is reflected by the signal line at least partially at a second determined position on the object.

[0045] - If the first determined location differs from the second determined location by at least a predefined difference threshold, then the location of the hand or body part, equivalent to touch positioning, is determined.

[0046] - If the difference between the first determined position and the second determined position is less than a predefined difference threshold, then the position of a hand or body part equivalent to the grasping hand position is determined, and

[0047] Perform the above steps for all possible pairings of a given location on the object.

[0048] In this way, the received reflective measurement signal, which includes at least two reflections, can reliably distinguish whether hand or body part positioning is equivalent to touch positioning or grasping / hand positioning.

[0049] In a preferred embodiment of the method, precise detection of hand or body part location on an object can be achieved. In these embodiments, the step of determining the location of a hand or body part on an object further includes...

[0050] - The amplitudes of the reflected and received measurement signals are compared with a predefined amplitude threshold, which depends on whether the determined hand or body part location is equivalent to touch location or grasping location.

[0051] - If the determined hand or body part location is equivalent to at least single-touch location and if the amplitude is greater than a predefined amplitude threshold used for touch location, then a fine hand or body part location equivalent to strong touch location is determined, and

[0052] - If the determined hand or body part location is equivalent to a grasping hand location and if the amplitude is greater than a predefined amplitude threshold used for grasping hand location, then a fine hand or body part location equivalent to a strong grasping hand location is determined.

[0053] In a preferred embodiment of the method, another finer detection of hand or body part location on an object can be obtained, wherein the step of determining the location of the hand or body part on the object further includes...

[0054] - Compare the signal width of the reflected and received measurement signals with a predefined signal width threshold.

[0055] - If the determined hand or body part location is equivalent to at least single touch location and if the signal width is greater than a predefined signal width threshold, then a fine hand or body part location equivalent to touch location of multiple fingers is determined.

[0056] - If the determined hand or body part location is equivalent to the grasping hand location and if the signal width is greater than a predefined signal width threshold, then a fine hand or body part location equivalent to the full-hand grasping hand location is determined.

[0057] In a preferred embodiment of the method, when the object is formed by the rim of a steering wheel, the step of determining the location of a hand or body part on the object further includes: determining a body part location equivalent to a knee driving location if the determined hand or body part location is equivalent to at least a single-touch location and if the position of the measurement signal on the rim, which is at least partially reflected by the signal line, has been determined to be at the lowest position of the rim in the current position of the steering wheel. This allows for the detection of misuse where the driver attempts to steer the vehicle using their knees.

[0058] In a preferred embodiment of the method, when the object is formed by the rim of a steering wheel, the step of determining the positioning of a hand or body part on the object further includes: determining the manipulation situation if at least one of the following conditions is met:

[0059] - It has been determined that the portion of the signal line that at least partially reflects the measurement signal is located at more than four positions on the object, and

[0060] - The location of a hand or body part, equivalent to single-touch positioning, has been determined within at least a predetermined time period.

[0061] By detecting the fulfillment of the first condition, it is possible to detect a driving condition in which another person besides the driver is touching or even gripping the rim of the steering wheel. By detecting the fulfillment of the second condition, it is possible to detect a driving condition in which the rim of the steering wheel is fixed in an impermissible manner.

[0062] In another aspect of the invention, a software module is provided for controlling the automatic execution of steps in embodiments of the method disclosed herein.

[0063] The method steps to be performed are converted into program code for a software module, wherein the program code can be implemented in a digital memory unit of a sensing system for hand positioning detection on a steering wheel, and can be executed by a processor unit of the sensing system. Preferably, the digital memory unit and / or processor unit can be the digital memory unit and / or processing unit of a control and evaluation unit of the sensing system. The processor unit can alternatively or supplementarily be another processor unit specifically designated to perform at least some of the method steps.

[0064] The software module enables robust and reliable execution of the method and allows for rapid modification of method steps.

[0065] These and other aspects of the invention will become apparent from the embodiments described below and will be elucidated with reference to the embodiments described below.

[0066] It should be noted that the features and measures individually detailed in the foregoing description can be combined with each other in any technically meaningful manner, and further embodiments of the invention are shown. The invention is characterized and described in detail, in particular, in conjunction with the accompanying drawings. Attached Figure Description

[0067] Further details and advantages of the invention will become apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings, in which:

[0068] Figure 1 The diagram schematically illustrates a sensing system according to the invention for detecting the positioning of a hand or body part on an object formed by the rim of a steering wheel in an installed state.

[0069] Figure 2 It schematically shows the following based on Figure 1 The conductive signal lines of the sensing system

[0070] Figure 3 The illustration schematically shows the situation in a scenario where both hands are touching the steering wheel (dual-touch positioning). Figure 1 The sensing system,

[0071] Figure 4 It is based on Figure 3 In the scenario, according to Figure 1 A schematic diagram of the reflection measurement signal received by the sensing system.

[0072] Figure 5 The illustration schematically shows the situation in a scenario where one hand is gripping the steering wheel (grip positioning). Figure 1 The sensing system,

[0073] Figure 6 It is based on Figure 5 In the scenario, according to Figure 1 A schematic diagram of the reflection measurement signal received by the sensing system.

[0074] Figure 7 The illustration schematically shows the situation in a scenario where both hands grip the steering wheel (grip positioning). Figure 1 The sensing system,

[0075] Figure 8 It is based on Figure 7 In the scenario, according to Figure 1A schematic diagram of the reflection measurement signal received by the sensing system.

[0076] Figure 9 The illustration schematically shows the situation in a scenario where one hand touches the steering wheel and the other hand grips the steering wheel (mixed hand positioning). Figure 1 The sensing system,

[0077] Figure 10 It is based on Figure 9 In the scenario, according to Figure 1 A schematic diagram of the reflection measurement signal received by the sensing system.

[0078] Figure 11 By operation according to Figure 1 A flowchart illustrating a method for using a sensing system to detect hand positioning on the steering wheel, and

[0079] Figures 12 to 14 Showing according to Figure 11 Optional steps of the method.

[0080] In different accompanying drawings, the same parts always have the same reference numerals or numbers. Therefore, they are usually described only once. Detailed Implementation

[0081] Figure 1 A sensing system 10 according to the invention is schematically illustrated for detecting the location of a hand or body part on an object formed by the rim 40 of a steering wheel 38 in an installed state. For clarity, only the rim 40 or the steering ring of the steering wheel 38 is shown, which also includes at least one spoke that connects the rim 40 to the steering column via a hub in a manner known per se. The steering wheel 38 can be used in vehicles designed as passenger cars, but can also be used in aircraft or ships.

[0082] The sensing system 10 includes a conductive signal line 12, a signal voltage source 26, and a control and evaluation unit 28.

[0083] The signal line 12 of the sensing system 10 is in Figure 2 The diagram illustrates the signal line 12 schematically. The signal line 12 can be shaped into a zigzag pattern comprising multiple half-circle shaped turns connected by straight sections. The signal line 12 can be designed as a coplanar waveguide with a conductive center line and two conductive return lines arranged at equal intervals on either side of the center line. The center line and return lines can be attached to a flexible dielectric carrier 14, such as a polymer foil, for example, by applying a screen printing method. In this way, the signal line 12 is designed to have a predefined uniform characteristic impedance, which can be arranged by changing the geometry and relative positions of the center line and return lines, as is known in the art.

[0084] The flexible dielectric carrier 14 is supported by a conductive ground plane that serves as an additional return line for the coplanar waveguide.

[0085] Signal line 12 can be as follows Figure 2 The diagram shown is open, but it can also be terminated with a lumped impedance equal to the characteristic impedance to avoid reflections at its ends. In the open case, total internal reflection is expected, which can be used as a time reference marker.

[0086] The maximum dimension between adjacent turning points 16 of the zigzag pattern of the signal line 12 is adapted to the circumference of the cross-section of the rim 40 of the steering wheel 38, such that the maximum lateral dimension between adjacent turning points 16 of the zigzag pattern is greater than 25% and less than 50% of the circumference of the cross-section of the rim 40 of the steering wheel 38, and in this particular embodiment it may be approximately 30% of the circumference.

[0087] like Figure 1 As shown, the conductive signal line 12 is arranged to extend along a major portion of the surface of the rim 40 of the steering wheel 38. The signal line 12 includes a first portion 18, which is arranged to extend along a major portion of the surface 20 of the rim 40 of the steering wheel 38, facing the operator of the steering wheel 38, typically the driver of the vehicle. The signal line 12 also includes a second portion 22, which is arranged to extend along a major portion of the surface 24 of the rim 40 of the steering wheel 38, facing away from the operator of the steering wheel 38. The first portion 18 and the second portion 22 of the signal line 12 are electrically connected in series without impedance discontinuity.

[0088] Signal line 12 is mounted and arranged on the surface of the rim 40 of the steering wheel 38, with prior knowledge of the relationship between the distance of any portion of signal line 12 from a reference point and information about its position on the rim 40. Any point of signal line 12 can be selected as a reference point. The position of any portion of signal line 12 on the rim 40 can be defined by specifying a surface (i.e., surface 20 facing the operator or surface 24 facing away from the operator) and by specifying a central angle relative to the zero-angle position.

[0089] Signal voltage source 26 is operatively electrically connected to signal line 12 and configured to provide a time-correlated measurement signal to travel along the connected signal line 12. In this embodiment, signal voltage source 26 is designed as an essential part of control and evaluation unit 28, sharing the same housing to improve signal processing and control of control and evaluation unit 28. In other embodiments, signal voltage source 26 may be designed as a separate unit with appropriate signal and control lines to signal line 12 and control and evaluation unit 28.

[0090] In this specific embodiment, the signal voltage source 26 is designed to provide a pulse shaping signal, but in other embodiments, the signal voltage source may be configured to provide a sweep signal, a pseudo-random phase shift keying signal, or a pseudo-random signal.

[0091] The control and evaluation unit 28 is operatively connected to the signal line 12 and the signal voltage source 26. The control and evaluation unit 28 may include a microcontroller comprising a digital data memory unit 32, a processor unit 30 having data access rights to the digital data memory unit 32, and a control interface 34. As will be explained below, the control and evaluation unit 28 is configured to receive a measurement signal after it has been reflected at least partially by at least a portion of the measurement signal already provided by the signal line 12, to determine one or more positions of one or more portions of the at least partially reflected measurement signal by the signal line 12 on the rim 40, and to determine hand positioning on the steering wheel 38 based on the determined one or more positions of the one or more portions of the signal line 12.

[0092] In the following text, reference will be made to Figure 1 and Figures 3 to 10 as well as Figure 11 Description by operation Figure 1 An embodiment of a method for using a sensing system 10 to detect the positioning of a hand or body part on an object formed by the rim 40 of the steering wheel 38. Figure 11 A flowchart of the method is provided. When preparing to operate the sensing system 10, it should be understood that all involved units and devices are in an operational state and as follows: Figure 1 The configuration shown.

[0093] To enable automated execution of the method, the control and evaluation unit 28 includes a software module 36. The method steps to be executed are converted into program code in the software module 36. This program code is implemented in the digital data storage unit 32 of the control and evaluation unit 28 and can be executed by the processor unit 30 of the control and evaluation unit 28. Alternatively, the software module 36 may reside in another control unit of the vehicle and be executable by that other control unit, and a data communication unit established between the control and evaluation unit 28 and the vehicle control unit will be used to achieve mutual data transmission.

[0094] refer to Figure 1 and Figure 11In the first step 50 of the method, a time-related measurement signal is provided to signal line 12 by operating signal voltage source 26. The measurement signal is intended to travel along the connected signal line 12. With no hands positioned on steering wheel 38 and signal line 12 terminated with lumped impedance, no reflection is expected. The provision of the time-related measurement signal can be controlled by control and evaluation unit 28. In other embodiments, the provision of the time-related measurement signal can serve as a trigger signal for control and evaluation unit 28 to begin executing the following steps.

[0095] In another step 52 of the method, the control and evaluation unit 28 is operated to receive the measurement signal (also referred to as the received reflected measurement signal) after the measurement signal has been reflected at least partially by at least a portion of the signal line 12.

[0096] In the next step 54, the operation control and evaluation unit 28 determines one or more positions on the rim 40 of one or more portions of the signal line 12 that have at least partially reflected the measurement signal. This is obtained by using prior knowledge of the relationship between the distance of any portion of the signal line 12 from the reference point and information about its position on the rim 40.

[0097] Then, in a further step, the control and evaluation unit 28 is operated to determine the hand positioning on the steering wheel 38 based on one or more determined positions of one or more portions of the signal line 12.

[0098] In the case that only one position of the portion of the signal line 12 that has partially reflected the measurement signal is determined on the rim 40, the control and evaluation unit 28 determines the hand positioning equivalent to single-touch positioning in step 56.

[0099] Figure 3 The sensing system 10 is schematically shown in a scenario where both hands 42 are touching the steering wheel 38 (dual-touch positioning), wherein one hand 42 is touching the operator-facing surface 20 of the rim 40, and the other hand 42 is touching the operator-rejecting surface 24 of the rim 40.

[0100] Figure 4 It is based on Figure 3 In the scenario, according to Figure 1 A schematic diagram of the reflected measurement signal 44 received by the sensing system 10. The vertical axis of the graph relates to the signal amplitude, while the horizontal axis relates to the circumferential position on the rim 40, starting from a reference point and extending to a portion of the signal line 12, as determined by the control and evaluation unit 28.

[0101] Based on the received reflection measurement signal 44, two positions of the signal line 12, which partially reflects the measurement signal on the rim 40, have been determined. In step 60 of the method, the control and evaluation unit 28 compares the first determined position of the first determined portion of the partially reflected measurement signal of the signal line 12 on the rim 40 with the second determined position of the second portion of the partially reflected measurement signal of the signal line 12 on the rim 46.

[0102] from Figure 4 It is clear that the two determined positions are different. More specifically, their difference is greater than a predefined difference threshold Δ. Based on this result of comparison step 60, control and evaluation unit 28 determines the hand position equivalent to the touch position in another step 62.

[0103] All predefined values, thresholds, and conditions mentioned herein can reside in the digital data memory unit 32 of the control and evaluation unit 28 and can be easily retrieved by the processor unit 30 of the control and evaluation unit 28.

[0104] Figure 5 The illustration schematically depicts a scenario where one hand 42 grips the steering wheel 38 (grip positioning). Figure 1 The sensing system 10. Similarly, the received reflection measurement signal 44 ( Figure 6 The two positions of the signal line 12 on the rim 40, which had already partially reflected the measurement signal, were determined. Figure 4 The received reflection measurement signal 44 is compared, and the two determined positions match within a predefined difference threshold Δ. For this result of comparison step 60, control and evaluation unit 28 determines the hand position equivalent to the grasping hand position in another step 64.

[0105] Figure 7 The illustration schematically shows the scenario where both hands 42 grip the steering wheel 38 (grip positioning). Figure 1 The sensing system 10. Figure 8 It is based on Figure 7 In the scenario, according to Figure 1 A schematic diagram of the reflection measurement signal 44 received by the sensing system 10.

[0106] Based on the received reflected measurement signal 44, four locations on the rim 40 of the signal line 12 where the measurement signal is partially reflected have been determined. As previously described, in step 58 of the method, the control and evaluation unit 28 selects a pair of first and second determined locations, and in step 60 compares the first determined location on the rim 40 where the first portion of the partially reflected measurement signal of the signal line 12 is located with the second determined location on the rim 40 where the second portion of the partially reflected measurement signal of the signal line 12 is located, and determines the hand positioning based on the result of comparison step 60. Comparison step 60 is performed on all possible pairs of the four determined locations on the rim 40. If the two determined locations match within a predefined difference threshold Δ, the control and evaluation unit 28 determines 64 a hand positioning equivalent to the grasping hand positioning for the considered location pairing. This is the case where two determined location pairs are identified, and the control and evaluation unit 28 determines 64 a hand positioning equivalent to the grasping hand positioning of both hands 42.

[0107] Figure 9 The illustration schematically shows the situation where one hand 42 touches the steering wheel 38 and the other hand 42 grips the steering wheel 38 (i.e., mixed hand positioning). Figure 1 The sensing system 10. Figure 10 It is based on Figure 9 In the scenario, according to Figure 1 A schematic diagram of the reflection measurement signal 44 received by the sensing system 10.

[0108] Based on the received reflected measurement signal 44, three positions on the rim of the signal line 12 where the partially reflected measurement signal has been determined have been identified. As previously described, in step 58 of the method, the control and evaluation unit 28 selects a pairing of the first and second identified positions, and in step 60 of the method, the control and evaluation unit 28 compares the first identified position of the partially reflected measurement signal of the signal line 12 on the rim 40 with the second identified position of the partially reflected measurement signal of the signal line 12 on the rim 40; and determines the hand positioning based on the result of comparison step 60. Comparison step 60 is performed for all possible pairings between the three identified positions on the rim 40.

[0109] from Figure 10 It can be clearly seen that two of the three identified positions match within a predefined difference threshold Δ. For these positions under consideration, control and evaluation unit 28 determines hand position 64, which is equivalent to the grasping hand position. The third position differs from each of the other two positions by an amount greater than the predefined difference threshold Δ. Based on this result of comparison step 60, control and evaluation unit 28 determines hand position 62, which is equivalent to the touch position of the third position.

[0110] For example Figure 3 , 5 For all hand positions determined in the scenarios shown in 7 and 9, the control and evaluation unit 28 can perform optional steps to determine fine hand positions.

[0111] for Figure 5 and Figure 7 The scene shown and Figure 9 In the scenario where the grip hand positioning is determined, the steps for determining the hand positioning on the steering wheel may further include: operating the control and evaluation unit 28 to compare the amplitude of the received reflection measurement signal 44 with a predefined amplitude threshold used for grip hand positioning. If the amplitude is greater than the predefined amplitude threshold used for grip hand positioning, the control and evaluation unit 28 determines a fine hand positioning equivalent to strong grip hand positioning; otherwise, a standard grip hand positioning is determined.

[0112] Alternatively, the step of determining the hand positioning on the steering wheel may further include: operating the control and evaluation unit 28 to compare the signal width of the received reflection measurement signal 44 with a predefined signal width threshold. If the signal width is greater than the predefined signal width threshold, the control and evaluation unit 28 determines a fine hand positioning equivalent to full-hand grip positioning; otherwise, it determines a standard grip positioning.

[0113] for Figure 3 The scene shown and Figure 9 The touch positioning determined in the scenario shown, the step of determining the hand positioning on the steering wheel 38, may further include: the operation control and evaluation unit 28 comparing the amplitude of the received reflection measurement signal 44 with a predefined amplitude threshold used for touch positioning. If the amplitude is greater than the predefined amplitude threshold used for touch positioning, the control and evaluation unit 28 determines a fine hand positioning equivalent to strong touch positioning; otherwise, a standard touch positioning is determined.

[0114] Alternatively, the step of determining hand positioning on steering wheel 38 may further include: operating control and evaluation unit 28 to compare the signal width of the received reflection measurement signal 44 with a predefined signal width threshold. If the signal width is greater than the predefined signal width threshold, control and evaluation unit 28 determines a fine hand positioning equivalent to multi-finger touch positioning; otherwise, it determines a standard touch positioning.

[0115] Figure 12 and Figure 13 The illustration shows further optional steps of a method that can allow misuse detection during driving conditions. As yet another optional step of the method ( Figure 12If the determined hand or body part positioning is equivalent to at least single-touch positioning and if the position of the signal line 12 that at least partially reflects the measurement signal on the rim 40 has been determined to be at the lowest position of the rim 40 under the current position of the steering wheel 38, then 66 can be determined to be a body part positioning equivalent to knee driving positioning.

[0116] As this method ( Figure 13 Another optional step in determining the location of hand or body parts 56, 62, and 64 includes: determining operation condition 68 if at least one of the following conditions is met:

[0117] - The locations on the object at least partially reflecting the measurement signal of signal line 12 have been determined to be at more than four positions, and

[0118] - The location of a hand or body part, equivalent to single-touch positioning, has been determined within at least a predetermined time period T.

[0119] While the invention has been detailed and described in the accompanying drawings and the foregoing description, such description is to be considered illustrative or exemplary rather than restrictive; the invention is not limited to the disclosed embodiments.

[0120] Those skilled in the art, when practicing the claimed invention, can understand and implement other variations of the disclosed embodiments by studying the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality, where "a plurality" is intended to indicate a quantity of at least two. The fact that certain measures are enumerated in mutually different dependent claims does not indicate that a combination of these measures cannot be used advantageously. Any reference numerals in the claims should not be construed as limiting the scope.

[0121] List of reference numerals

[0122] 10. Sensing System

[0123] 12 signal lines

[0124] 14 Flexible dielectric carrier

[0125] 16 Turning Point

[0126] 18 Part One

[0127] 20 Surface

[0128] 22 Part Two

[0129] 24 Surface

[0130] 26 Signal voltage source

[0131] 28 Control and Evaluation Unit

[0132] 30 processor units

[0133] 32 Digital Data Memory Units

[0134] 34 Control Interface

[0135] 36 Software Modules

[0136] 38 Steering Wheel

[0137] 40 rim

[0138] 42 hands

[0139] 44 Reflection Measurement Signal

[0140] Δ Predefined difference threshold

[0141] T is a predefined time period.

[0142] step:

[0143] 50. Provide measurement signals to the signal line.

[0144] 52. Receive reflection measurement signal

[0145] 54. Determine the position of the portion of the signal line's reflected measurement signal on the rim. 56. Determine single-touch positioning.

[0146] 58. Select the pairing of the two determined positions.

[0147] 60. Compare the determined positions on the wheel rim.

[0148] 62. Determine touch positioning

[0149] 64. Determine the gripper hand position

[0150] 66. Determine knee positioning for driving

[0151] 68. Determine the manipulation situation.

Claims

1. A sensing system (10) for detecting the positioning of a hand or other body part on the rim (40) of a steering wheel (38), the sensing system (10) comprising: - At least one conductive signal line (12) is arranged to extend along a portion of the surface of the rim (40) with prior knowledge of the relationship between: the distance of any portion of the at least one conductive signal line (12) from a reference point, and information about its position on the rim (40). - A signal voltage source (26), which operates to be connected to each signal line (12) and is configured to provide a time-dependent measurement signal to travel along the corresponding connected signal line (12), and - Control and evaluation unit (28), which operates to be able to connect to each signal line (12) and is configured to: After the measurement signal is reflected by at least a portion of the measurement signal provided by the signal line (12), the measurement signal is received (52). Determine (54) one or more locations on the object where at least part of the signal line (12) reflects the measurement signal, and Based on the determined positions of one or more portions of the signal line (12), the location of a hand or other body part on the object is determined (56, 62, 64); The at least one conductive signal line (12) comprises: a first portion (18) extendable along a portion of the rim (40) of the steering wheel (38) facing the operator; and a second portion (22) extendable along a portion of the rim (40) of the steering wheel (38) facing away from the operator, wherein the first portion (18) and the second portion (22) are electrically connected in series; and The control and evaluation unit (28) is further configured to: detect at least one hand grasping the object based on at least two positions where the measurement signal on the rim (40) is at least partially reflected by the signal line (12) if at least two positions where the measurement signal on the rim (40) is at least partially reflected by the signal line (12) have been determined.

2. The sensing system (10) according to claim 1, wherein, The at least one conductive signal line (12) is shaped into a zigzag pattern such that the maximum lateral dimension between adjacent turning points (16) of the zigzag pattern is greater than 25% and less than 50% of the circumference of the cross-section of the rim (40) of the steering wheel (38).

3. The sensing system (10) according to claim 2, wherein, The zigzag pattern includes semi-circular turns connected by straight sections.

4. The sensing system (10) according to claim 1 or 2, wherein, At least one conductive signal line (12) is designed as a microstrip line or a coplanar waveguide, either of which includes a flexible dielectric carrier (14).

5. The sensing system (10) according to claim 1 or 2, wherein, At least one conductive signal line (12) is terminated by at least one lumped impedance equal to the characteristic impedance of the at least one conductive signal line (12).

6. The sensing system (10) according to claim 1 or 2, wherein, The signal voltage source (26) is configured to provide a pulse shaping signal, a frequency sweep signal, a pseudo-random phase shift keying signal, or a pseudo-random signal.

7. A steering wheel (38) with hand positioning detection, comprising a sensing system (10) as described in any one of claims 1 to 6, wherein, The at least one conductive signal line (12) is arranged to extend along a major portion of the surface of the rim (40) of the steering wheel (38).

8. A method for detecting the positioning of a hand or other body part on the rim (40) of a steering wheel (38) by means of an operation sensing system (10), said sensing system (10) comprising: At least one conductive signal line (12) is arranged to extend along a portion of the surface of an object with prior knowledge of the relationship between the distance of any portion of the at least one conductive signal line (12) from a reference point and information about its position on the object; a signal voltage source (26) is operable to be connected to each signal line (12); and a control and evaluation unit (28) is operable to be connected to each signal line (12), wherein the at least one conductive signal line (12) comprises: a first portion (18) operable to extend along a portion of the rim (40) of the steering wheel (38) facing the operator of the steering wheel (38); and a second portion operable to extend along a portion of the rim (40) of the steering wheel (38) facing away from the operator of the steering wheel (38), wherein the first portion (18) and the second portion (22) are electrically connected in series, the method comprising at least the following steps: - By operating the signal voltage source (26), a time-related measurement signal (50) intended to travel along the correspondingly connected signal line (12) is provided to the signal line (12); - Operate the control and evaluation unit (28) to receive (52) the measurement signal after the measurement signal has been reflected by at least a portion of the measurement signal provided by the signal line (12). - Operate the control and evaluation unit (28) to determine (54) the locations on the object of one or more portions of the signal line (12) that have at least partially reflected the measurement signal; and - Operate the control and evaluation unit (28) to determine (56, 62, 64) the location of a hand or other body part on the object based on one or more determined positions of one or more portions of the signal line (12); - If at least two positions where the signal line (12) has at least partially reflected the measurement signal on the rim (40) have been determined, then the control and evaluation unit (28) is operated to determine at least one hand gripping the object based on at least two positions where the signal line (12) has at least partially reflected the measurement signal on the rim (40).

9. The method according to claim 8, wherein, The step (56) of determining the location of a hand or other body part on an object includes: determining the location of a hand or other body part equivalent to single-touch positioning if only one position of the measurement signal on the rim (40) where the signal line (12) has at least partially reflected has been determined.

10. The method according to claim 8 or 9, wherein, The steps for determining the location of a hand or other body part on objects (62, 64) include: - Compare (60) a first determined position on the object where at least a portion of the signal line (12) at least partially reflects the measurement signal with a second determined position on the object where at least a second portion of the signal line (12) at least partially reflects the measurement signal. -If the first determined position differs from the second determined position by at least a predefined difference threshold (Δ), then (62) is determined to be equivalent to touch-based positioning of the hand or other body part. - If the difference between the first determined position and the second determined position is less than the predefined difference threshold (Δ), then (64) is determined to be equivalent to the hand or other body part positioning of the grasping hand, and - Perform the above steps for all possible pairings of the determined positions on the object.

11. The method according to claim 8 or 9, wherein, The step of determining the location of a hand or other body part on the object further includes: - The amplitudes of the reflected and received measurement signals are compared with a predefined amplitude threshold, which depends on whether the determined hand or other body part location is equivalent to touch location or grasping location. - If the determined hand or other body part location is equivalent to at least single-touch location and if the amplitude is greater than the predefined amplitude threshold used for touch location, then a fine hand or other body part location equivalent to strong touch location is determined, and - If the determined hand or other body part location is equivalent to a gripping hand location and if the amplitude is greater than the predefined amplitude threshold used for gripping hand location, then a fine hand or other body part location equivalent to a strong gripping hand location is determined.

12. The method according to claim 8 or 9, wherein, The step of determining the location of a hand or other body part on the object further includes: - Compare the signal width of the reflected and received measurement signals with a predefined signal width threshold. - If the determined hand or other body part location is equivalent to at least single touch location and if the signal width is greater than the predefined signal width threshold, then a fine hand or other body part location equivalent to touch location of multiple fingers is determined. - If the determined hand or other body part location is equivalent to a grasping hand location and if the signal width is greater than the predefined signal width threshold, then a fine hand or other body part location equivalent to a full-hand grasping hand location is determined.

13. The method according to claim 8 or 9, wherein, The object is formed by the rim (40) of the steering wheel (38), and wherein the step of determining (56, 62, 64) the positioning of a hand or other body part on the object further includes: determining (66) other body part positioning equivalent to knee driving positioning if the determined hand or other body part positioning is equivalent to at least single touch positioning and if the position of the measurement signal on the rim (40) which has at least partially reflected the signal line (12) has been determined to be at the lowest position of the rim (40) below the current position of the steering wheel (38).

14. The method according to claim 8 or 9, wherein, The object is formed by the rim (40) of a steering wheel (38), and the step of determining (56, 62, 64) the positioning of a hand or other body part on the object further includes determining the manipulation situation (68) if at least one of the following is satisfied: - At least four or more locations on the object where the portion of the signal line (12) that reflects the measurement signal has been determined, and - The location of a hand or other body part, equivalent to single-touch positioning, has been determined for at least a predetermined period of time.

15. A software module (36) for controlling the automatic execution of the method as described in any one of claims 8 to 14, wherein, The method steps to be performed are converted into program code of the software module (36), wherein the program code can be implemented in the digital data storage unit (32) of the sensing system (10) as claimed in any one of claims 1 to 6 or in a separate control unit, and can be executed by the processor unit (30) of the sensing system (10) as claimed in any one of claims 1 to 6 or in a separate control unit.

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