WO2007041465A1

WO2007041465A1 - Redundant angle sensor

Info

Publication number: WO2007041465A1
Application number: PCT/US2006/038381
Authority: WO
Inventors: Mark E. Lacroix
Original assignee: Timken Us Corporation
Priority date: 2005-09-29
Filing date: 2006-09-29
Publication date: 2007-04-12

Abstract

A redundant sensing apparatus (100) includes a magnet assembly (104) , a first sensor (116) , and a second sensor (120) . The magnet assembly generates a magnetic field. The first sensor is positioned in magnet assembly (104) to generate a first signal based on the magnetic field generated by the magnet assembly. The second sensor (120) is positioned adjacent the first sensor (116) to generate a second signal based on the magnetic field generated by the magnet assembly.

Description

REDUNDANT ANGLE SENSOR

RELATED APPLICATION

[0001] This application claims priority to U.S. Provisional Patent Application Serial No. 60/721,748, filed on September 29, 2005, the entire contents of which are incorporated herein by reference.

FIELD

[0002] Embodiments of the invention relate generally to sensing systems and methods, and particularly to systems and methods of sensing angles.

BACKGROUND

[0001] For enhanced reliability, non-contact sensing systems often use additional or redundant sensors. The use of additional or redundant sensors increases manufacturing costs, and requires additional space to accommodate the sensors and related components. For example, some non-contact sensing systems use two sensors and include magnets, rotors, piloting means, printed circuit boards, and housing assemblies. The addition of these components increases the size of a non-contact sensing system, and requires additional process operations that create or generate the required space. Furthermore, additional wiring is needed to connect these components to the sensors.

[0002] An example of a non-contact sensing system is an angle sensor that uses a Hall device or sensor. Such an angle sensor is typically built by placing a magnet assembly around a stationary Hall device or sensor. The magnet assembly typically consists of a one- piece permanent magnetic ring or two semicircular permanent magnets. As a result of this configuration, the stationary Hall device is positioned in a magnetic field created by the magnet assembly. An angle is therefore formed between the magnetic field and an axis defined by the Hall device.

[0003] Such an angle sensor is generally characterized by a sensor transfer function that receives as input the angle between the magnetic field and the axis of the Hall device, and outputs a corresponding voltage. As the magnet assembly rotates, the angle between the magnetic field and the axis of the Hall device changes, which in turn changes the output of the sensor. In some cases, the output is essentially a sine wave that has one full electrical cycle or period for each mechanical revolution of the magnet assembly. The output becomes nearly linear near the zero crossings of the transfer function. However, the signal loses the linearity as the angle increases or as the angular sense range expands.

SUMMARY

[0003] In one form, the invention provides a redundant sensing apparatus. The sensing apparatus includes a magnet assembly configured to generate a magnetic field. The sensing apparatus also includes a first sensor positioned in the magnet assembly, and configured to generate a first signal based on the magnetic field generated by the magnet assembly. The sensing apparatus also includes a second sensor positioned adjacent the first sensor, and configured to generate a second signal based on the magnetic field generated by the magnet assembly.

[0004] In another form, the invention provides a method of redundantly sensing a magnetic field radiated from a magnet assembly. The method includes sensing the magnetic field with first and second sensors. The method also includes generating a first signal with one of the first and second sensors based on the sensed magnetic field, and generating a second signal with the other of the first and second sensors based on the sensed magnetic field.

[0005] In yet another form, the invention provides a redundant sensing apparatus that includes a magnetic field generating assembly, and first and second sensors. The magnetic field generating assembly is operable to generate a magnetic field. The first and second sensors are arranged in a stack configuration, configured to be partially enclosed by the magnetic field generating assembly, and operable to generate at least one of first and second signals in response to the magnetic field passing through the first and second sensors.

[0006] In yet another form, the invention provides a redundant sensing assembly that includes a steering assembly, a shaft, a magnetic field generating assembly, a first sensor, and a second sensor. The steering assembly is operable to rotate. The shaft is coupled to the steering assembly to rotate in response to the rotating steering assembly. The magnetic field generating assembly is coupled to the shaft to generate a magnetic field. The first sensor is positioned proximate to the magnetic field generating assembly to detect the magnetic field and to generate a first signal based on the magnetic field. The second sensor is positioned proximate to the first sensor and the magnetic field generating assembly to detect the magnetic field and to generate a second signal based on the magnetic field.

[0007] Embodiments herein can reduce the cost of manufacturing redundant sensors, as well as reduce the size of redundant sensors.

[0004] Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] FIG. IA is a top schematic view of a non-contact redundant angle sensing apparatus.

[0006] FIG. IB is a side schematic view of the non-contact redundant angle sensing apparatus of FIG. IA.

[0007] FIG. 2 is a graph showing a transfer function of the sensing apparatus of FIGS. IA and IB.

[0008] FIG. 3 A is a second top schematic view of a second non-contact redundant angle sensing apparatus.

[0009] FIG. 3 B is a second side schematic view of the second non-contact redundant angle sensing apparatus of FIG. 3 A.

[0010] FIG. 4 shows a steering wheel position detection system according to an embodiment of the invention.

[0011] FIG. 4A shows a cross-sectional view of a portion of the steering wheel position detection system of FIG. 4.

[0012] FIG. 5 shows an axle system in a vehicle according to an embodiment of the invention.

[0013] FIG. 6 shows an exemplary kingpin assembly for use with the axle system of FIG. 5. [0014] FIG. 7 shows a perspective view of a second steering axle position detection system.

[0015] FIG. 8 shows a perspective view of a rotor portion and a stator portion of a redundant sensing assembly.

[0016] FIG. 9 shows a perspective view of the assembled redundant sensing assembly of FIG. 8.

DETAILED DESCRIPTION

[0017] Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms "mounted," "connected," "supported," and "coupled" and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, "connected" and "coupled" are not restricted to physical or mechanical connections or couplings.

[0018] Embodiments of the invention will also be described with reference to the accompanying drawing figures wherein like numbers represent like elements throughout. Certain terminology, for example, "top," "bottom," "right," "left," "front," "frontward," "forward," "back," "rear," and "rearward," is used in the following description for relative descriptive clarity only and is not intended to be limiting.

[0019] Embodiments of the invention relate to a sensing apparatus for redundantly sensing angular motion of an object. In one embodiment, the sensing apparatus includes a first sensor that is proximate to a second sensor. Both the first and second sensors are configured to generate respective first and second signals based on a magnetic field surrounding the first and second sensors. The sensing apparatus also includes a magnet assembly configured to generate the magnetic field such that the magnetic field surrounds both the first and second sensors, and can be detected by both the first and second sensors.

[0020] Embodiments of the invention provide a redundant sensor assembly including a rotating magnet assembly and piloting means. In some embodiments, the piloting means (e.g., plastic magnet holder) are used to secure the magnet assembly. At least two Hall devices are placed adjacent to each other such that a common magnetic field from the magnet assembly passes through each of the Hall devices as the magnet assembly rotates. In this way, the sensor assembly allows both of the Hall devices to be placed or mounted on a printed circuit board, and thus reduces the cost of the sensor assembly. For full redundancy, the printed circuit board can have separate sections for each of the Hall devices. Partial redundancy can be achieved by using a common power connection and a common ground wire, and keeping a plurality of outputs from each of the Hall devices separate. A common connector can also be used for both Hall devices on the circuit board. In this way, additional components, such as the printed circuit board, magnet carrier, housing, and additional connections for the second common connector, are saved. When the additional components are not used, additional process operations and wire routing processes can be eliminated. Furthermore, the size of the redundant sensor assembly can also be reduced. The sensor assembly also works for other magnetic circuits where one or more magnets are rotated around a magnetic field sensor.

[0021] FIGS. IA and IB show a top schematic view and a side schematic view of an exemplary non-contact Hall based redundant angle sensing apparatus 100, respectively. The sensing apparatus 100 includes a field generating assembly 104 mounted for rotation about a given axis 106. Although the field generating assembly 104 as shown in FIG. 1 includes a pair of semi-circular arcs 108, 112 that extend about the circumference of the field generating assembly 104, the field generating assembly 104 can also include a single ring magnet, a cylindrical magnet, a ring having a plurality of magnetic arcs, and the like.

[0022] A pair of angle sensors 116, 120 is mounted proximate to the axis 106. In some embodiments, the angle sensors 116, 120 include Hall devices. In the illustrated embodiment, the angle sensors 116, 120 are arranged in a stack configuration. In an exemplary stack configuration, the angle sensors 116, 120 are positioned adjacent to each other. Although only two angle sensors 116, 120 are shown in the FIG. IA embodiment, the sensing apparatus 100 can include other number of angle sensors to provide additional redundancy.

[0023] As shown in FIGS. IA and IB, the angle sensors 116, 120 are fixed or stationary relative to the field generating assembly 104 such that the field generating assembly 104 rotates relative to the angle sensors 116, 120. As such, a common field, such as a magnetic field from the field generating assembly 104, surrounds and passes through both of the angle sensors 116, 120. In this way, as the field generating assembly 104 rotates, the angle sensors 116, 120 can detect a change in a direction or an angle of the field generated by the field generating assembly 104 with respect to the angle sensors 116, 120. As a result of detecting the field or the angle changes, each of the angle sensors 116, 120 generates a respective signal to indicate the angle or the field detected.

[0024] Although FIG. IA shows a stationary pair of sensors 116, 120 positioned in the field generated by the rotating assembly 104, the pair of sensors 116, 120 can be configured to be rotating relative to a stationary assembly 104 in other embodiments. Furthermore, in still other embodiments, both the pair of sensors 116, 120 and the assembly 104 are rotating. In such cases, dynamic parameters such as speeds and rotating directions of at least one of the respective rotating sensors 116, 120 and the assembly 104 are used to determine the relative angles.

[0025] The sensing apparatus 100 is generally characterized by a system function or a transfer function that relates the angle between the magnetic field generated by the field generating assembly 104 and the stationary angle sensors 116, 120 to an output voltage of each of the angle sensors 116, 120. That is, the output voltage of each of the angle sensors 116, 120 is a function of the angle between the magnetic field and the respective angle sensor 116, or 120.

[0026] FIG. 2 shows an exemplary transfer function 200 that characterizes the angle sensors 116, 120 of the sensing apparatus 100 shown in FIGS. IA and IB. Particularly, angles of the magnetic field generated by the field generating assembly 104 are measured along an x-axis 204, and output voltages of each of the angle sensors 116, 120 are measured along a y-axis 208. Curve 212 illustrates a first transfer function of one of the angle sensors 116, 120. Curve 216 illustrates a second transfer function of the other of the angle sensors 116, 120. Particularly, the curve 216 shows an inverted version of curve 212 such that output signals governed by the second transfer function can be readily differentiated from output signals governed by the first transfer function. Other transfer functions can be employed. For example, FIG. 2 shows a third curve 220 that represents the second transfer function with an offset relative to the first transfer function. Having two different curves therefore allows the signals generated by the first and second sensors via the first and second transfer functions to be analyzed effectively. That is, if one of the angle sensors 116, 120 fails to generate an output voltage, the other of the angle sensors 116, 120 can be readily recognized as being operational.

[0027] In one embodiment, the angle sensors 116, 120 are mounted on a common printed circuit board ("PCB") (not shown). For a full redundant system, the angle sensors 116,. 120 are mounted on separate sections of a PCB. Each of the separate sections has a power connector, a ground connector, and an output connector. As such, when one of the angle sensors 116, 120 fails, the other of the angle sensors 116, 120 is isolated and unaffected. For a partial redundant system, the angle sensors 116, 120 can be configured to share some connections such as a common power, a common ground, and a common connector between the two sections. In the partial redundancy configuration, while the angle sensors 116, 120 can share some connections as described, the angle sensors 116, 120 have different output connections. In this way, one of the angle sensors 116, 120 can continue to function if the other of the angle sensors 116, 120 fails. In some other embodiments, when the signals generated by the angle sensors 116, 120 do not align within a tolerance band, the sensing apparatus 100 can generate a sensor failure signal, and can be shut down.

[0028] FIGS. 3 A and 3B show second top and side schematic views of a second non- contact redundant angle sensing apparatus 132, respectively. The sensing apparatus 132 includes the stationary angle sensors 116, 120. Particularly, the angle sensors 116, 120 are fixed or stationary relative to the field generating assembly 104 such that the field generating assembly 104 rotates relative to both of the angle sensors 116, 120. In the embodiment shown, the field generating assembly 104 includes first and second discrete magnets 136, 140 positioned on a ring 144. As the ring 144 and its discrete magnets 136, 140 rotate relative to the surrounded angle sensors 116, 120, the angle sensors 116, 120 generate signals such as those shown in FIG. 2. In this way, the sensing apparatus 132 can use smaller and stronger magnets, and thus provide better accuracy. [0029] Although FIG. 3 A shows a stationary pair of sensors 116, 120 positioned in the field generated by the rotating ring 144, the pair of sensors 116, 120 can be configured to be rotating relative to a stationary ring 144 in other embodiments. Furthermore, in still other embodiments, both the pair of sensors 116, 120 and the ring 144 are rotating. In such cases, dynamic parameters such as speeds and rotating directions of at least one of the respective rotating sensors 116, 120 and the ring 144 are used to determine the relative angles.

[0030] Embodiments herein can be used to detect steering wheel position or wheel position in vehicle (e.g., automotive) applications, as well as in other critical angle position sensing applications, robotic applications, packaging applications, and manufacturing assembly applications. Furthermore, embodiments herein can also be used in other equipment, such as agricultural equipment, earth moving equipment, off-road equipment, forklifts, and on-road vehicles.

[0031] FIG. 4 shows a steering wheel position detection system 400 according to an embodiment of the invention. The detection system 400 includes a steering wheel 404 coupled to one end 408 of a steering wheel shaft or column 412, and a redundant sensing assembly 416 coupled to another end 420 of the steering wheel column 412. FIG. 4A shows a cross-sectional view of the end 420. Particularly, a plurality of semi-circular magnetic arcs 424 are attached to the column end 420, and encompass a pair of stationary sensors 428 arranged in a stack configuration as discussed with respect to FIGS. 1 - 3B. The sensors 428 are connected to a redundant sensing circuit board 432 having a plurality of conductors 436 connected thereto for communicating information between the board 432 and other devices (not shown).

[0032] In operation, magnetic fields radiated from the magnetic arcs 424 are detected by one or both of the sensors 428. When the steering wheel 404 is turned, the steering column 412 in turn rotates in response to the turning steering wheel 404. While the magnetic fields radiated from the magnetic arcs 424 generally remain the same, angles at which the magnetic fields are detected by the stationary sensors 428 change in response to the rotating steering column 412. When one of the stationary sensors 428 fails, the other of the stationary sensors 428 either continues or starts to generate signals indicative of the changing magnetic fields.

[0033] FIG. 5 shows an axle system 500 of a vehicle (not shown) according to an embodiment of the invention. The axle system 500 includes an upper kingpin 504, a lower kingpin 508, and a wheel hub 512. Particularly, the upper kingpin 504 includes a steering axle position detection system therein. FIG. 6 shows an exemplary kingpin assembly 600 that can be used with the upper kingpin 504 of FIG. 5 to detect a wheel angle or an angle at which a wheel is turning. The assembly 600 includes a bearing 604 positioned near a shaft assembly 608 that rotates with the kingpin assembly 600 and provides rotation for a magnet assembly therein (not shown), such as the magnet assemblies 104 of FIGS. IA and 3 A. The magnet assembly is positioned near a plurality of redundant sensors incorporated in a stationary portion 612 of the shaft assembly 608.

[0034] FIG. 7 shows a perspective view of a second steering axle position detection system 700 for use in a vehicle (not shown) having a second kingpin 704. The second kingpin 704 is coupled to a wheel (not shown), while a stationary portion 708 is fixedly mounted to a portion 712 of the vehicle.

[0035] FIG. 8 shows a perspective view of a redundant sensing assembly 800, which is similarly to the assembly 100 of FIG. 1. The assembly 800 includes a rotor portion 804 that further includes a field generating assembly 808 having a pair of magnets 812, and a through- hole 814. The assembly 800 also includes a stator portion 816 having a plurality of sensors 820 incorporated in a center pin 824. The sensors 820 generally communicate with external devices via a plurality of conductors 828.

[0036] FIG. 9 shows a perspective view of an assembled redundant sensing assembly 800'. Particularly, the assembled redundant sensing assembly 800' results from snapping or inserting the center pin 824 of the stator portion 816 into the through-hole 814 of the rotor portion 804 of FIG. 8. Radial projections 832 extended outwardly from the center pin 824 secure the rotor portion 804 to the stator portion 816. In the embodiment shown, the rotor portion 804 has a turning angle of ± 60°. It is to be appreciated that the turning angle can be more or less in other embodiments. Although FIG. 8 shows that the conductors 828 exit from the assembled redundant sensing assembly 800' on a side thereof, the conductors 828 can also exit from the assembled redundant sensing assembly 800' in other ways. Furthermore, the assembled redundant sensing assembly 800' can also communicate with external devices wirelessly in other embodiments.

[0037] Various features and advantages of the invention are set forth in the following claims.

Claims

1. A redundant sensing apparatus comprising:

a magnet assembly configured to generate a magnetic field;

a first sensor positioned in the magnet assembly, and configured to generate a first signal based on the magnetic field generated by the magnet assembly; and

a second sensor positioned adjacent the first sensor, and configured to generate a second signal based on the magnetic field generated by the magnet assembly.

2. The sensing apparatus of claim 1 , wherein the magnet assembly is configured to enclose at least a portion of the first and second sensors.

3. The sensing apparatus of claim 1, wherein the first and second sensors comprise respective Hall sensors.

4. The sensing apparatus of claim 1, wherein the magnetic field defines a field axis, wherein the first and second sensors define a sensor axis, and wherein the first and second signals are a function of the field axis and the sensor axis.

5. The sensing apparatus of claim 1, wherein the magnet assembly rotates relative to the first and second sensors.

6. The sensing apparatus of claim 1, wherein the magnet assembly comprises at least one of a magnetic ring, a ring having a plurality of magnetic arcs, and a ring having a plurality of discrete magnets positioned thereon.

7. The sensing apparatus of claim 1, further comprising a circuit board coupled to the first and second sensors to receive the first and second signals.

8. The sensing apparatus of claim 7, wherein the circuit board comprises a plurality of sections, wherein each of the plurality of sections comprises a respective power connection and a respective ground connection, each of the plurality of sections is coupled to the respective first and second sensors, and each of the plurality of sections is coupled to another of the plurality of sections with a common connector.

9. A method of redundantly sensing a magnetic field radiated from a magnet assembly, the method comprising:

sensing the magnetic field with first and second sensors;

generating a first signal with one of the first and second sensors based on the sensed magnetic field; and

generating a second signal with the other of the first and second sensors based on the sensed magnetic field.

10. The method of claim 9, further comprising enclosing at least a portion of the first and second sensors with the magnet assembly.

11. The method of claim 9, wherein the first and second sensors comprise respective Hall sensors, and wherein sensing the magnetic field further comprises sensing the magnetic field with the respective Hall sensors.

12. The method of claim 9, wherein the magnetic field defines a field axis, wherein the first and second sensors define a sensor axis, and wherein the first and second signals are a function of the field axis and the sensor axis.

13. The method of claim 9, further comprising rotating the magnet assembly relative to the first and second sensors.

14. The method of claim 9, wherein the magnet assembly comprises at least one of a magnetic ring, a ring having a plurality of magnetic arcs, and a ring having a plurality of discrete magnets positioned thereon.

15. The method of claim 9, further comprising :

coupling the first and second sensors to a circuit board; and

receiving the first and second signals at the circuit board.

16. The method of claim 15, wherein the circuit board comprises a plurality of sections, the method further comprising: coupling at least one of a respective power connection and a respective ground connection to each of the plurality of sections;

coupling each of the plurality of sections to the respective first and second sensors; and

coupling each of the plurality of sections to another of the plurality of sections with a common connector.

17. A redundant sensing apparatus comprising:

a magnetic field generating assembly operable to generate a magnetic field; and

first and second sensors arranged in a stack configuration, configured to be partially enclosed by the magnetic field generating assembly, and operable to generate at least one of first and second signals in response to the magnetic field passing through the first and second sensors.

18. The sensing apparatus of claim 17, wherein the magnetic field generating assembly rotates relative to the first and second sensors.

19. The sensing apparatus of claim 17, further comprising a circuit board configured to be coupled to the first and second sensors to receive the first and second signals.

20. The sensing apparatus of claim 19, wherein the circuit board comprises a plurality of sections, wherein each of the plurality of sections comprises a respective power connection and a respective ground connection, each of the plurality of sections is configured to be coupled to the respective first and second sensors, and each of the plurality of sections is configured to be coupled to another of the plurality of sections with a common connector.

21. A redundant sensing assembly comprising:

a steering assembly operable to rotate;

a shaft coupled to the steering assembly, and operable to rotate in response to rotation of the rotating steering assembly;

a magnetic field generating assembly coupled to the shaft, and operable to generate a magnetic field; a first sensor positioned proximate to the magnetic field generating assembly, and configured to detect the magnetic field and to generate a first signal based on the magnetic field; and

a second sensor positioned proximate to the first sensor and the magnetic field generating assembly, and configured to detect the magnetic field and to generate a first signal based on the magnetic field.

22. The redundant sensing assembly of claim 21, wherein the magnetic field generating assembly is configured to enclose at least a portion of the first and second sensors.

23. The redundant sensing assembly of claim 21, wherein the first and second sensors comprise respective Hall sensors.

24. The redundant sensing assembly of claim 21, wherein the magnetic field defines a field axis, wherein the first and second sensors define a sensor axis, and wherein the first and second signals are a function of the field axis and the sensor axis.

25. The redundant sensing assembly of claim 21, wherein the magnetic field generating assembly rotates relative to the first and second sensors.

26. The redundant sensing assembly of claim 21 , wherein the magnetic field generating assembly comprises at least one of a magnetic ring, a ring having a plurality of magnetic arcs, and a ring having a plurality of discrete magnets positioned thereon.

27. The redundant sensing assembly of claim 21 , wherein the redundant sensing assembly is installed in a vehicle.

28. The redundant sensing assembly of claim 21 , wherein the steering assembly comprises one of a kingpin assembly and a steering wheel assembly.