Handwheel with touchless sensor device

Abstract

A handwheel, e.g., a steering wheel for a motorized vehicle, with a human-machine interface (HMI) for contactless entry of commands by gestures is proposed. The HMI comprises a sensing surface as a capacitive sensor with a detection chipset connected to the electrodes of the sensing surface for determining first, second, third and fourth capacitance observables, an orientation sensor and a processor. The processor is configured to compute a time series of position coordinates depending on the capacitance observables, to compensate the rotation of the steering wheel and to map the time series of rotation-compensated position coordinates onto one or more commands and to output these commands.

Description

HANDWHEEL WITH TOUCHLESS SENSOR DEVICEBackground of the Invention

[0001] The invention generally relates to a handwheel, such as , e.g., a racing wheel (game controller), a handwheel for a valve, a steering wheel for a motor vehicle (e.g., a bus, a car, a truck, a tram, a locomotive, a lawn-and-garden tractor, etc.)Summary of the InventionAccording to the invention, a handwheel with a human-machine interface (HMI) for contactless entry of commands by gestures is proposed. The HMI comprises a sensing surface, a capacitive sensor made of the electrodes of the sensing surface for determining first, second, third and fourth capacitance observables, a detection chipset, an orientation sensor and a processor. The processor is configured to compute a time series of position coordinates depending on the capacitance observables, to compensate the rotation of the steering wheel and to map the time series of rotation-compensated position coordinates onto one or more commands and to output these commands.

[0002] More specifically, the handwheel comprises a human-machine interface (HMI) for contactless entry of commands by gestures. The handwheel is configured for being mounted pivotable relative to a reference frame, e.g., a stationary reference frame. The HMI comprises: a sensing surface integrated into the handwheel so as to rotate with the handwheel when the handwheel is rotated, the sensing surface comprising a first sector with a first electrode, a second sector with a second electrode, a third sector with a third electrode and a fourth sector with a fourth electrode; a capacitive sensor connected to the first electrode for determining a first capacitance observable, to the second electrode for determining a second capacitance observable, to the third electrode for determining a third capacitance observable and to the fourth electrode for determining a fourth capacitance observable; an orientation sensor for determining an angular position (angle hereinafter denoted <p) of the handwheel relative to the reference frame;a processor connected to the capacitive sensor and to the orientation sensor, the processor configured to compute a time series of position coordinates in the reference frame, the position coordinates including first and second position coordinates, which, at an instant of time are computed as:where:X’ is the first position coordinate,Y’ is the second position coordinate,(p is the angular position of the handwheel relative to the reference frame,X = (CX1 -CX2) / (C1 +C2+C3+C4),Y = ((CY1 -CY2) / (C1 +C2+C3+C4),C1 is the first capacitance observable,C2 is the second capacitance observable,C3 is the third capacitance observable,C4 is the fourth capacitance observable at the instant of time,CX1 is C1 +C4 or CX1 is C1 ,CX2 is C2+C3 or, when CX1 is C1 , CX2 is C3,CY1 is C1 +C2 or, when CX1 is C1 , CY1 is C2, andCY2 is C3+C4 or, when CX1 is C1 , CY2 is C4.The processor is configured to map the time series of position coordinates onto one or more commands.

[0003] According to an embodiment, CX1 is C1 , CX2 is C3, CY1 is C2, and CY2 is C4. In this case, the centroid of the first electrode and the centroid of the third electrode lie on the X-axis (the axis of the X coordinates) in the (possibly rotating) reference frame attached to the handwheel while the centroid of the second electrode and the centroid of the fourth electrode lie on the Y-axis (the axis of the Y coordinates) in the (possibly rotating) reference frame attached to the handwheel. The X’ and Y’coordinates correspond to the X and Y coordinates after transformation into the reference frame in which the handwheel may rotate.

[0004] Alternatively, CX1 is C1 +C4, CX2 is C2+C3, CY1 is C1 +C2, and CY2 is C3+C4. In this case, the centroid of both the first electrode and the fourth electrode and the centroid of both the second electrode and the third electrode lie on the X-axis rotating with the handwheel while the centroid of both the first electrode and the second electrode and the centroid of both the third electrode and the fourth electrode lie on the Y-axis rotating with the handwheel. The X’ and Y’ coordinates correspond again to the X and Y coordinates after transformation into the reference frame in which the handwheel may rotate.

[0005] The orientation sensor may comprise an accelerometer or a gyroscope. Additionally or alternatively, the orientation sensor comprises a rotary encoder. The orientation sensor may also be comprised of an inertial measurement unit (IMU) with gyroscope, accelerometer and magnetometer sensors.

[0006] The first, second, third and fourth sectors may be arranged around a center of the sensing surface, the first sector being located opposite the third sector and the second sector being located opposite the fourth sector. The first, second, third and fourth sectors may be quadrants, i.e. , disk sectors with a central angle of 90°.

[0007] The position coordinates may include third position coordinates, which, at an instant of time are computed as Z’ = C1 +C2+C3+C4, where Z’ is the third position coordinate at the instant of time in the reference frame in which the handwheel may rotate. The Z’-axis may coincide with the rotation axis of the handwheel.

[0008] The sensing surface may comprise one or more counter-electrodes. The one or more counter-electrodes may be grounded or floating.

[0009] The processor may be configured to carry out the mapping of the time series of position coordinates onto one or more commands by pattern recognition.

[0010] The capacitive sensor may comprise one or more capacitance-to-digital converters with at least four sensing channels connected to the first, second, third and fourth electrodes, respectively.

[0011] According to a preferred embodiment, the handwheel is configured as a steering wheel for a motor vehicle.

[0012] In a preferred aspect, the invention relates to a motor vehicle, comprising the handwheel as described hereinabove. In this case, the reference frame is the motor vehicle’s reference frame, i.e. , the reference frame attached to the vehicle chassis.

[0013] In the present document, the verb “to comprise” and the expression “to be comprised of’ are used as open transitional phrases meaning “to include” or “to consist at least of”. Unless otherwise implied by context, the use of singular word form is intended to encompass the plural, except when the cardinal number “one” is used: “one” herein means “exactly one”. Ordinal numbers (“first”, “second”, etc.) are used herein to differentiate between different instances of a generic object; no particular order, importance or hierarchy is intended to be implied by the use of these expressions. Furthermore, when plural instances of an object are referred to by ordinal numbers, this does not necessarily mean that no other instances of that object are present (unless this follows clearly from context). When this description refers to “an embodiment”, “one embodiment”, “embodiments”, etc., this means that the features of those embodiments can be used in the combination explicitly presented but also that the features can be combined across embodiments without departing from the invention, unless it follows from context that features cannot be combined.Brief Description of the Drawings

[0014] By way of example, preferred, non-limiting embodiments of the invention will now be described in detail with reference to the accompanying drawings, in which:Fig. 1 : is a schematic view of a steering wheel according to an embodiment of the invention;Fig. 2: is a diagram of the HMI of the steering wheel of Fig. 1 ;Fig. 3: is an illustration of a first layout of a capacitive sensing surface;Fig. 4: is an illustration of a second layout of a capacitive sensing surface;Fig. 5: is an illustration of a third layout of a capacitive sensing surface.Detailed Description of Preferred Embodiments

[0015] Fig. 1 shows a steering wheel for a motor vehicle according to an embodiment of the invention. The steering wheel 10 comprises a ring 12 connected to a hub 14 byone or more spokes 16. The steering wheel 10 is mounted to the steering column (not shown) by the hub 14, which rotates with the ring 12 when the user makes a turn.

[0016] The steering wheel 10 comprises a HMI 18 for contactless entry of commands by gestures. The HM1 18 comprises a sensing surface 20 integrated into the handwheel 10 so as to rotate with the handwheel 10 when the handwheel 10 is rotated. In the illustrated embodiment, the sensing surface 20 is arranged in the hub 14 of the steering wheel, e.g., in a cover of the hub 14.

[0017] The sensing surface 20 is subdivided into four quadrants, each having a respective sensing electrode therein. Figs. 3-5 illustrate different, non-limiting layouts of the sensing surface 20. Each sensing electrode 22A, 22B, 22C, 22D may be surrounded by a respective counterelectrode. However, the counterelectrodes may be optional in certain configurations. The counterelectrodes may be grounded or floating.

[0018] As illustrated in Fig. 2, the sensing electrodes 22A, 22B, 22C, 22D are capacitive sensors connected with a detection chipset 24 integrating signal filtering and ADC (Analog-to-Digital converters) for determining corresponding capacitance observables C1 , C2, C3, C4, i.e., measured physical quantities indicative of the capacitance of the respective (sensing) electrode. The capacitance of each sensing electrode increases when a conductive or a dielectric moving object, e.g., the driver’s hand, approaches it. When the same object moves away from a sensing electrode, the respective capacitance decreases. The detection chipset 24 may comprise one or more capacitance-to-digital converters with at least four sensing channels connected to the first, second, third and fourth electrodes, respectively.

[0019] The capacitive sensor may include or be connected to a microprocessor or microcontroller 26 (e.g., an FPGA, an ASIC, a DSP or a CPU) that receives the capacitance observables C1 , C2, C3, C4 in digital format. The processor computes position coordinates as:X = ((C1 +C4)-(C2+C3)) / (C1 +C2+C3+C4),Y = ((C1 +C2)-(C3+C4)) / (C1 +C2+C3+C4),Z = C1 +C2+C3+C4.

[0020] The capacitance observables C1 , C2, C3, C4 may change over time and, accordingly, the computed position coordinates are time dependent. The timedependency has not been expressed explicitly in order not to overload the equations. X is the first position coordinate on an axis passing through the centroid of the first electrode and the fourth electrode (taken together) and through the centroid of the second electrode and the third electrode (taken together). Y is the second position coordinate on an axis passing through the centroid of the first electrode and the second electrode (taken together) and the centroid of the third electrode and the fourth electrode lie (taken together). The time series of X and Y coordinates indicate the trajectory of a conductive or a dielectric moving object in the rotating reference frame, e.g., the above-mentioned driver’s hand, over the sensing surface 20. The Z coordinate indicates a distance between the object and the sensing surface 20.

[0021] The microprocessor 26 receives the angle of rotation of the steering wheel, <p, from an orientation sensor 28. The orientation sensor 28 may comprise an accelerometer for sensing the direction of the Earth’s gravitational field or a gyroscope providing an angular position of the deviation of the rating steering wheel 10 from its reference position from the reference frame supporting the steering wheel 10. Additionally or alternatively, the orientation sensor comprises a rotary encoder on the shaft of the steering wheel 10. The rotary encoder may provide the angular position of the steering wheel.

[0022] The processor 26 is configured to compensate for the rotation of the steering wheel by transforming the position coordinates into the reference frame in which the steering wheel rotates:

[0023] The trajectory of the moving object, i.e. , the time series of the coordinates X’, Y’, Z’, is then mapped onto one or more commands, which are provided as outputs. The mapping of the time series of position coordinates onto one or more commands may be achieved by pattern recognition 27, including classification of the observed trajectory into the most likely among several classes. These classes preferably correspond to the different commands that the HMI may output. The pattern recognition step 27 thus translates the observed trajectories into commands. When the observed trajectory cannot be associated to a command with sufficient confidencelevel, the pattern recognition 27 may affect it to a class that does not correspond to a command.

[0024] The advantage of using the trajectory of the object not in the rotating reference frame (attached to the steering wheel) but in the reference frame in which the steering wheel rotates, i.e., in the reference frame of the motor vehicle, is that it is more intuitive for the driver to make gestures in their own reference frame than in the rotating reference frame of the steering wheel.

[0025] It should be noted that position coordinates, in particular in the capacitive sensing surface configuration of Fig.5, could, alternatively be computed as:X = (C1 -C3) / (C1 +C2+C3+C4),Y = (C2-C4)) / (C1 +C2+C3+C4),Z = C1 +C2+C3+C4.

[0026] In this case, X is the first position coordinate on an axis (rotating with the steering wheel) passing through the centroid of the first electrode and though the centroid of the third electrode while Y is the second position coordinate on an axis (rotating with the steering wheel) passing through the centroid of the second electrode and through the centroid of the fourth electrode. The Z coordinate indicates a distance between the object and the sensing surface. The transformation of the coordinates into the reference system in which the steering wheel rotates may be effected in the same manner as above.

[0027] While specific embodiments have been described herein in detail, those skilled in the art will appreciate that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention, which is to be given the full breadth of the appended claims and any and all equivalents thereof.

Claims

Claims:1 . A handwheel, for being mounted pivotable relative to a reference frame, comprising a human-machine interface for contactless entry of commands by gestures, the human-machine interface comprising a sensing surface integrated into the handwheel so as to rotate with the handwheel when the handwheel is rotated, the sensing surface comprising a first sector with a first electrode, a second sector with a second electrode, a third sector with a third electrode and a fourth sector with a fourth electrode; a detection chipset connected to the first electrode for determining a first capacitance observable, to the second electrode for determining a second capacitance observable, to the third electrode for determining a third capacitance observable and to the fourth electrode for determining a fourth capacitance observable; an orientation sensor for determining an angular position of the handwheel relative to the reference frame; a processor connected to the detection chipset and to the orientation sensor, the processor configured to compute a time series of position coordinates in the reference frame, the position coordinates including first and second position coordinates, which, at an instant of time are computed as:where X’ is the first position coordinate, Y’ is the second position coordinate, (p is the angular position of the handwheel relative to the reference frame, X = (CX1 -CX2) / (C1 +C2+C3+C4), Y = ((CY1-CY2) / (C1 +C2+C3+C4), C1 is the first capacitance observable, C2 is the second capacitance observable, C3 is the third capacitance observable, C4 is the fourth capacitance observable at the instant of time, CX1 is C1 +C4 or CX1 is C1 , CX2 is C2+C3 or, when CX1 is C1 , CX2 is C3, CY1 is C1 +C2 or, when CX1 is C1 , CY1 is C2, and CY2 is C3+C4 or, when CX1 is C1 , CY2 is C4; wherein the processor is further configured to map the time series of position coordinates onto one or more commands.

2. The handwheel as claimed in claim 1 , wherein the orientation sensor comprises an accelerometer.

3. The handwheel as claimed in claim 1 or 2, wherein the orientation sensor comprises a rotary encoder.

4. The handwheel as claimed in any one of claims 1 to 3, wherein the orientation sensor comprises an inertial measurement unit (IMU).

5. The handwheel as claimed in any one of claims 1 to 4, wherein the first, second, third and fourth sectors are arranged around a centre of the sensing surface, the first sector located opposite the third sector and the second sector located opposite the fourth sector.

6. The handwheel as claimed in claim 5, wherein the first, second, third and fourth sectors are quadrants.

7. The handwheel as claimed in any one of claims 1 to 6, wherein the position coordinates include third position coordinates, which, at an instant of time are computed as Z’ = C1 +C2+C3+C4, where Z’ is the third position coordinate at the instant of time.

8. The handwheel as claimed in any one of claims 1 to 7, wherein the processor is configured to carry out the mapping of the time series of position coordinates onto one or more commands by pattern recognition.

9. The handwheel as claimed in any one of claims 1 to 8, wherein the detection chipset comprises one or more capacitance-to-digital converters with at least four sensing channels connected to the first, second, third and fourth electrodes.

10. The handwheel as claimed in any one of claims 1 to 9, wherein CX1 is C1 +C4, CX2 is C2+C3, CY1 is C1 +C2, and CY2 is C3+C4.11 . The handwheel as claimed in any one of claims 1 to 9, wherein CX1 is C1 , CX2 is C3, CY1 is C2, and CY2 is C4.

12. The handwheel as claimed in any one of claims 1 to 11 , configured as a car steering wheel.

13. A motor vehicle, comprising the handwheel as claimed in claim 12, wherein the reference frame is the motor vehicle’s reference frame.

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