Steering wheel with hands-off detection

Abstract

A multifunctional steering wheel (110) with HOD Sensor comprises a steering wheel rim (112), a steering wheel hub (114) and a number of spokes (116) connecting the steering wheel rim to the steering wheel hub. At least one switch group (118) comprising a number of control switches operatively connected to a vehicle interface for controlling at least one vehicle function, is arranged on the steering wheel hub (114) and / or the spokes (116). The steering wheel (110) further comprises a HOD sensor comprising at least one HOD sensing element (126) arranged on or integrated in the steering wheel rim (112) and a HOD ECU (130) operatively connected to the HOD sensor element (126) for processing signals from the HOD sensing element to determine the presence and / or location of a driver's hands. In accordance with the invention, HOD ECU is integrated into said at least one switch group (118).

Description

Steering Wheel with Hands-Off DetectionTechnical field

[0001] The present invention generally relates to a steering wheel, e.g. for automotive vehicles, and more particularly to a steering wheel with Hands Off Detection (HOD).Background of the Invention

[0002] In modem vehicles, steering wheels are evolving to incorporate a variety of functionalities beyond traditional steering control. These multifunctional steering wheels enable drivers to interact with numerous vehicle systems, such as audio controls, navigation, communication, and cruise control, through integrated switches and buttons. As vehicle technology advances, the steering wheel has become a critical interface for enhancing driver convenience and safety.

[0003] One of the significant challenges in designing multifunctional steering wheels is the limited space available to integrate the various controls and sensors necessary for these advanced functions. The steering wheel must not only accommodate these additional controls but also ensure that their placement and operation do not compromise the primary function of steering and driver safety.

[0004] Moreover, with the advent of autonomous driving and advanced driver assistance systems (ADAS), it has become increasingly important to monitor the driver's engagement with the steering wheel. Hands-off detection is a critical feature that ensures the driver remains alert and ready to take control of the vehicle when necessary. This feature typically involves sensors that detect whether the driver’s hands are on the wheel and trigger alerts or corrective actions if the driver’s hands are off the wheel for a certain period. Steering wheels with HOD (Hands-off detection) systems are e.g. disclosed in GB 2 596 586 A or US 2019 / 0009812 A1.

[0005] The one or more sensors are typically integrated into the steering wheel rim and connected to a control module, which processes signals from the HOD sensing element to determine the presence and / or location of a driver’s hands. The control module is typically arranged in the center hub of the steering wheel. However, since the steering wheel hub also has to accommodate other components, such as e.g. an airbag module, a horn switch, etc., the space in the steering wheel hub is usuallyvery limited. This significantly reduces the design freedom for the different components and thus increases the costs of the components.Object of the invention

[0006] It is therefore desirable to provide a multifunctional steering wheel with Hands-Off detection sensor, without the above described shortcomings. This object is achieved by a multifunctional steering wheel according to claim 1 .General Description of the Invention

[0007] A multifunctional steering wheel with Hands-Off detection sensor, HOD Sensor, comprises a steering wheel rim, a steering wheel hub and a number of spokes connecting the steering wheel rim to the steering wheel hub. At least one switch group comprising a number of control switches operatively connected to a vehicle interface for controlling at least one vehicle function, is arranged on the steering wheel hub and / or the spokes. The control switches may control various vehicle functions, including but not limited to audio, navigation, cruise control, and communication systems.

[0008] The steering wheel further comprises a HOD sensor comprising at least one HOD sensing element arranged on or integrated in the steering wheel rim and a HOD control unit (HOD ECU) operatively connected to the HOD sensor element for processing signals from the HOD sensing element to determine the presence and / or location of a driver’s hands. In most multifunctional steering wheels, the at least one switch group comprises a main unit, which has active electronic components like MCU, communication transceiver, etc. as well as switches and connectors, and a sub unit which has only switches and connectors and which is operatively connected to said main unit. In such a steering wheel, the main unit is operatively connected to the vehicle interface and the sub unit is operatively connected to said main unit, each said main unit and said sub unit comprising a number of control switches. In accordance with the invention, the HOD ECU is integrated into said sub unit of said at least one switch group.

[0009] In the context of the present invention, the expression “the HOD ECU is integrated into said at least one switch group” is to be understood in such a way that the HOD ECU and the switch group are physically arranged together in a commonmounting location, preferably into a common housing (i.e. the housing of the switch group). This integration may be achieved by simply arranging the circuit boards of both devices into the common housing, or in a more advanced integration, by arranging the electrical components of the switch group and the HOD ECU on a common circuit board. In the steering wheel according to the present invention, the integration of the HOD ECU into the switching group enables to free up space in the steering wheel hub, thereby increasing the freedom of design for the other components to be accommodated in the hub. On the other hand, the switching group usually has sufficient redundant space to enable the accommodation of the HOD ECU without increasing the overall size of the switching group. The present invention thus enables to reduce the overall size of the components to be integrated into the steering wheel, and thereby makes the task to integrate the different components into the steering wheel easier and thus less expensive.

[0010] It will be noted that by integrating the HOD ECU into the switching group, the present invention also eliminates the need for a specific housing for the HOD ECU. The HOD ECU is integrated into the same housing as the switching group and therefore a dedicated HOD ECU housing is no longer needed, which again enables to save costs for the overall system.

[0011] In a preferred embodiment, said control switches of said sub unit are arranged on one or more circuit boards. In this case, the HOD ECU is preferably integrated on one of said one or more circuit boards. This embodiment enables a further reduction of individual parts by eliminating the need for a dedicated circuit board for the HOD ECU. This embodiment thus makes use of the fact, that the switch group or switch group(s) usually have redundant space to populate electronic components for HOD on the printed circuit board.

[0012] The switch group comprises at least one switch group ECU, which processes the inputs of the different switches and converts them into control signals for the various vehicle functions to be controlled by the switch group. In embodiments, the HOD ECU may then be integrated into said switch group ECU. Such an embodiment thus relies on an integrated ECU for both the switch control and the HOD sensor. Such a highly integrated combined ECU results of course in the optimal space saving for the accommodation of the components into the steering wheel. It is however noted, that the integration of different control functions into asingle ECU may be technically challenging since the different control functions may have very specific requirements and limitations which are not always easy to combine together.

[0013] In a preferred embodiment, the HOD ECU is integrated on the printed circuit board of the sub unit on which the switches of the sub unit are mounted. This embodiment provides an appropriate solution from the perspective of both cost saving and technical feasibility to integrate HOD ECU into the subsidiary switch unit which usually have redundant space to populate electronic components for the HOD on the PCB.

[0014] It will be appreciated, that in embodiments, the main unit and said sub unit are arranged at different positions on said steering wheel hub or on different spokes. The main and sub unit are preferably arranged on the spokes on the left and right side of the steering wheel hub.

[0015] It is further noted that the control switches of the switch group may comprise any type of switches suitable for controlling the various vehicle functions. The control switches may e.g. comprise one or more of push-buttons and / or rotary switches and / or touch pads, etc.

[0016] The skilled person will finally appreciate, that the invention is not limited to a very specific type of HOD sensor. In fact, the HOD sensor may be based on touch sensors, such as e.g. pressure sensors, arranged on the steering wheel rim (below the trim). In other embodiments, the HOD sensing element may be a capacitive sensing mat and the HOD control unit is configured to determine the presence and / or location of a driver’s hands based on the influence on an electric field generated around said capacitive sensing mat. This type of capacitive sensing principle is widely used in the HOD in various configurations with single sensing electrodes or multiple electrodes.

[0017] In yet another embodiment, the HOD sensor may be a TDR-based HOD system in which the HOD sensing element comprises at least one signal line arranged along at least a portion of a surface of the steering wheel rim while the HOD control unit is configured to send a time-dependent detection signal traveling along the signal line, receive a reflected signal traveling along the signal line and detect the presence of a hand on the surface based on the reflected signal. SuchTDR-based HOD systems use the principles of time domain reflectometry to detect hand presence on the steering wheel by analyzing reflected electrical signals. This method offers high sensitivity, reliability, and seamless integration, making it a promising technology for modern vehicles equipped with advanced driver assistance systems.Brief Description of the Drawings

[0018] Further details and advantages of the present invention will be apparent from the following detailed description of not limiting embodiments with reference to the attached drawing, wherein:Fig.1 a schematic representation of the components of a multifunctional steering wheel according to the prior art;Fig. 2 a schematic representation of an embodiment of a multifunctional steering wheel according to the invention;Fig. 3 a view of the details of the components of an embodiment of a multifunctional steering wheel according to the invention;Fig. 4 a schematic representation of another embodiment of a multifunctional steering wheel according to the invention.Description of Preferred Embodiments

[0019] A multifunctional steering wheel 110 according to the prior art is illustrated in FIG. 1. The steering wheel 110 comprises a steering wheel skeleton encased in foam and consisting of a steering wheel rim 112, a steering wheel hub 114 and spokes 116. The spokes 116 connect the steering wheel rim 112 to the steering wheel hub.

[0020] Two switch groups 118 and 120 are arranged on the spokes 116 on either side, left and right, of the steering wheel hub 114. Each switch group 118 and 120 comprises a number of control switches which are operatively connected to a vehicle interface for controlling at least one vehicle function.

[0021] In the steering wheel shown in Fig. 1 , switch group 118 is the main unit, which has active electronic components like MCU, communication transceiver, etc. as well as switches and connectors, and is operatively connected to the vehicleinterface via wiring harness 122. Switch group 120 on the other hand is a sub unit which has only switches and connectors and which is operatively connected to said main unit 118 by means of wiring harness 124.

[0022] The steering wheel finally is equipped with a HOD sensor, which comprises at least one HOD sensing element 126 arranged on or integrated in the steering wheel rim 112. The HOD sensing element 126 is typically arranged below the trim layer 128, e.g. the leather trim, of the steering wheel 110. This is indicated in Fig. 1 by the broken away portion of the trim layer 128 where the underlying HOD sensing element 126 is made visible.

[0023] A HOD control unit (HOD ECU) 130 is operatively connected to the HOD sensor element 126 by means of a wiring harness 132. In operation, the HOD ECU 130 operates the HOD sensing element 126 and processes signals from the HOD sensing element 126 to determine the presence and / or location of a driver’s hands on the steering wheel. As shown in Fig. 1 , the HOD ECU is arranged in the steering wheel hub 114 and operatively connected to the vehicle interface by means of wiring harness 134.

[0024] It will be noted that typically the switch groups 1 18 and 120 as well as the HOD ECU each comprise a printed circuit board on which the corresponding electronic components such as micro-controllers, CAN / LIN communication transceivers as well as passive components like connectors of switches are arranged. Furthermore, each of the circuit boards is typically arranged in a housing, e.g. made of plastic material, so that the overall size of the different components makes integration into the steering wheel a challenging task.

[0025] Fig. 2 schematically illustrates an embodiment of a multifunctional steering wheel in accordance with the present invention. In this embodiment, the HOD ECU is integrated into the switch group 220, i.e. into the sub unit. The HOD sensor element 226 is connected to the HOD ECU in the switch group 220 by wiring harness 232. On the other hand, switch group 220 is connected to the main unit, i.e. switch group 218, by means of wiring harness 224. By means of the same wiring harness 224, the HOD ECU may be connected to switch group 218 and from there to the vehicle interface via common wiring harness 222. This embodiment thus allows to free up space in the steering wheel hub 214 since the HOD ECU does not require a separate housing to be accommodated in the hub 214. Furthermore, sincethe HOD ECU may be operatively connected to the vehicle interface via the commonly used wiring harnesses 222 and 224, the embodiment uses one wiring harness less than the prior art and thus further reduces the number of individual parts like connectors and the like.

[0026] Fig. 3 shows the detailed arrangement of the HOD ECU integration into the switch group.

[0027] Both the main unit switch group 318 and the sub unit switching group 320 comprise a number of control switches 336 mounted on respective printed circuit boards 338 and 340. The main unit switch group 318 further comprises the switch group ECU 342 mounted on the respective circuit board 338. The control switches 336 of the main unit switch group 318 are operatively connected to the switch group ECU 342 by means of an internal wiring 344. The control switches 336 of the sub unit switch group 320 are also operatively connected to the switch group ECU 342 by means of wiring harness 324.

[0028] The HOD sensor element 326 is connected to the HOD ECU 330 in the sub unit switch group 320 by wiring harness 332. HOD ECU 330 is mounted together with the control switches 336 of the sub unit switch group 320 on the respective circuit board 340. The HOD ECU 330 is operatively connected, together with the control switches 336 of the sub unit switch group 320, with the main unit switch group 318 by means of common wiring harness 324. Both the signals from the switch group ECU 342 and from the HOD ECU 330 are transmitted to the vehicle interface via the common wiring harness 322.

[0029] Fig. 4 shows a different embodiment of a steering wheel, in which the HOD ECU is integrated entirely into the switch group ECU 442. As a result, the printed circuit board 440 of the sub unit switch group 420 does not require to be equipped with a specific ECU as all the control functions are integrated in the switch group ECU 442. This embodiment further reduces the number of individual electronic components by a higher integration of the different functions into common microcontrollers. However as noted before, the integration of different control functions into a single ECU may be technically challenging since the different control functions may have very specific requirements and limitations which are not always easy to combine together.List of Reference Symbols210, 310, 410 steering wheel212, 312, 412 steering wheel rim214, 314, 414 steering wheel hub216, 316, 416 spokes218, 318, 418 switch group, main unit220, 320, 420 switch group, sub unit222, 322, 422 wiring harness to vehicle interface224, 324, 424 wiring harness between switch groups226, 326, 426 HOD sensing element228 trim layer330 HOD ECU232, 332, 432 wiring harness HOD sensor336, 436 control switches338, 340, 438, 440 printed circuit board342, 442 switch group ECU344, 444 Internal wiring

Claims

Claims1 . Multifunctional steering wheel with Hands-Off detection sensor, HOD Sensor, said steering wheel comprising- a steering wheel rim, a steering wheel hub and a number of spokes connecting the steering wheel rim to the steering wheel hub,- at least one switch group comprising a number of control switches operatively connected to a vehicle interface for controlling at least one vehicle function, said switch group being arranged on the steering wheel hub and / or the spokes, and- a HOD sensor comprising at least one HOD sensing element arranged on or integrated in the steering wheel rim and a HOD control unit (HOD ECU) operatively connected to the HOD sensor element for processing signals from the HOD sensing element to determine the presence and / or location of a driver’s hands; characterized in that said at least one switch group comprises a main unit and a sub unit, said main unit being operatively connected to the vehicle interface and said sub unit being operatively connected to said main unit, each said main unit and said sub unit comprising a number of control switches, and wherein said HOD ECU is integrated into said sub unit.

2. Multifunctional steering wheel according to claim 1 , wherein said control switches of said sub unit are arranged on one or more circuit boards, and wherein said HOD ECU is integrated on one of said one or more circuit boards.

3. Multifunctional steering wheel according to any one of claims 1 or 2, wherein said switch group comprises at least one switch group ECU, and wherein said HOD ECU is integrated into said switch group ECU.

4. Multifunctional steering wheel according to any one of claims 1 to 3, wherein said main unit and said sub unit are arranged at different positions on said steering wheel hub or on different spokes.

5. Multifunctional steering wheel according to any one of claims 1 to 4, wherein said control switches comprise one or more of push-buttons and / or rotary switches and / or touch pads.

6. Multifunctional steering wheel according to any one of claims 1 to 5, wherein the HOD sensing element is a capacitive sensing mat and wherein the HOD control unit is configured to determine the presence and / or location of a driver’s hands based on the influence on an electric field generated around said capacitive sensing mat.

7. Multifunctional steering wheel according to any one of claims 1 to 5, wherein the HOD sensing element comprises at least one signal line arranged along at least a portion of a surface of the steering wheel rim and wherein the HOD control unit is configured to send a time-dependent detection signal traveling along the signal line, receive a reflected signal traveling along the signal line and detect the presence of a hand on the surface based on the reflected signal.

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