Magnetic sensor system

Abstract

This invention provides a magnetic sensor system comprising a magnet mounted at the end of a rotatable shaft, a magnetic induction device including a multi-turn magnetic sensor, and a mechanism for initializing the multi-turn magnetic sensor to a known state for use. When the magnetic induction device is used to monitor the rotation of the shaft, the magnet is positioned at an initial position at a first distance from the magnetic induction device such that the magnetic field strength sensed by the magnetic induction device is within the operating window of the multi-turn magnetic sensor, defined by a minimum magnetic flux density Bmin and a maximum magnetic flux density Bmax. The mechanism includes a member for axially moving the magnet and the shaft toward the magnetic induction device such that the magnetic field sensed by the magnetic induction device exceeds the upper limit Bmax of the operating window. This causes nucleation of magnetic domain walls, thereby filling the sensor helix with magnetic domain walls and magnetizing all magnetoresistive elements to the same state. After initialization, the mechanism is configured to return the magnet to its initial position for use. In this respect, the mechanism may have a biasing device, such as a spring, which biases the magnet to the initial position.

Description

Technical Field

[0001] This invention relates to a magnetic sensor system. More specifically, this invention relates to a magnetic sensor system comprising a multi-turn magnetic sensor and a mechanism for initializing the multi-turn magnetic sensor. Background Technology

[0002] Magnetic multi-turn (MT) sensors are commonly used in applications requiring monitoring the number of rotations of a device, such as a steering wheel in a vehicle. MT sensors typically use magnetoresistive elements that are sensitive to an applied magnetic field. The resistance of the magnetoresistive element in a MT sensor can be changed by rotating a magnetic field near the sensor. The change in the magnetoresistive element's resistance can be tracked to determine the number of turns in the magnetic field, which can then be converted to the number of turns in the monitored device.

[0003] The magnetic turns information stored in the sensor needs to match the physical turns count of the sensor monitoring device; therefore, the sensor must first be set to a known magnetic state before it can be used. Thus, the magnetoresistive element needs to be magnetically initialized to one of two states so that all sensor outputs are identical at either the starting point (i.e., zero turns of the magnetic field) or the ending point (i.e., the maximum number of turns the sensor can count) of the mechanical system—for example, both having a "high" reading or a "low" reading. This is called the initialization state. Summary of the Invention

[0004] This invention provides a magnetic sensor system comprising a magnet mounted at the end of a rotatable shaft, a magnetic induction device including a multi-turn magnetic sensor, and a mechanism for initializing the multi-turn magnetic sensor to a known state for use. When the magnetic induction device is used to monitor the rotation of the shaft, the magnet is positioned at an initial position at a first distance from the magnetic induction device such that the magnetic field strength sensed by the magnetic induction device is within the operating window of the multi-turn magnetic sensor, defined by a minimum magnetic flux density Bmin and a maximum magnetic flux density Bmax. The mechanism includes a member for axially moving the magnet and the shaft toward the magnetic induction device such that the magnetic field sensed by the magnetic induction device exceeds the upper limit Bmax of the operating window. This causes nucleation of magnetic domain walls, thereby filling the sensor helix with magnetic domain walls and magnetizing all magnetoresistive elements to the same state. After initialization, the mechanism is configured to return the magnet to its initial position for use. In this respect, the mechanism may have a biasing device, such as a spring, which biases the magnet to the initial position.

[0005] A first aspect of the present invention provides a magnetic sensor system including a magnetic induction device, the magnetic induction device including at least a magnetic multi-turn sensor, wherein the magnetic multi-turn sensor includes a plurality of magnetoresistive sensing elements, a magnet is mounted on a rotatable shaft, the magnet is positioned at a first distance from the magnetic induction device such that the magnetic multi-turn sensor is operable to measure the number of turns of a magnetic field generated by the magnet, and an initialization mechanism is configured to move the magnet and the rotatable shaft axially toward the magnetic induction device such that when the magnet is at a second distance from the magnetic induction device, the magnetic field generated by the magnet generates magnetic domain walls in the plurality of magnetoresistive elements.

[0006] Similarly, when the magnet is in the first position, the magnetic field strength sensed by the multi-turn sensor is within its operating window, thus it accurately outputs the number of turns information. To initialize the multi-turn sensor to a known magnetic state, the magnet and the axial sensor are moved axially. This causes the magnetic field strength sensed by the multi-turn sensor to exceed the operating window, thereby filling the sensor with magnetic domain walls and magnetizing all magnetoresistive elements to the same state. After initialization, the magnet and shaft return to their initial positions for use.

[0007] It will be recognized that the first distance is greater than the second distance. The magnetic multi-turn sensor may have an operating window between a first magnetic field strength and a second magnetic field strength, and wherein when the magnet is at the second distance, the magnetic field strength sensed by the magnetic induction device is greater than the second magnetic field strength of the operating window.

[0008] In some arrangements, the initialization mechanism may include a movable element configured to drive the shaft axially. The initialization mechanism may also include a support element disposed around and held in a fixed axial position around the rotatable shaft; and a biasing element coupled between the support element and the movable element, the biasing element being configured to bias the movable element to a first position, wherein the magnet is at a first distance when the movable element is in the first position. For example, the biasing element may be a spring. However, it should be understood that any component suitable for biasing the movable element to the first position may be used.

[0009] In some arrangements, the initialization mechanism may include an alignment mechanism configured to hold the magnet and the rotatable shaft at a predetermined angular position as the rotatable shaft moves axially toward the magnetic induction device. For example, the alignment mechanism may include: a key attached to one side of the rotatable shaft; and an opening on the support element, arranged around the rotatable shaft and held in a fixed axial position, wherein the opening is configured to receive the key as the magnetic induction device moves axially. By providing such an alignment mechanism, the shaft can only move axially when it is in a specific angular position (i.e., when the key is aligned with the opening), thereby ensuring initialization occurs when the magnetic field is in the correct direction. In this respect, the direction of the magnetic field during initialization must correspond to the direction of the magnetic field when the rotatable shaft is at its starting point (i.e., corresponding to zero turns) or its ending point (i.e., corresponding to the maximum number of turns).

[0010] The initialization mechanism may further include a locking mechanism configured to hold the rotatable shaft in a first axial position such that the magnet and the magnetic induction device maintain a first distance, wherein the locking mechanism is unlocked to allow axial movement of the magnet and the rotatable shaft. This helps prevent the shaft from moving axially during normal operation due to vibrations from an external system. Any axial movement will result in a change in the magnetic field strength, which could lead to incorrect rotation counts. For example, the locking mechanism may include a retaining ring. However, it should be understood that the locking mechanism can be any mechanism suitable for absorbing vibrations that may interfere with rotation counts.

[0011] Magnetic multi-turn sensors can be multi-turn sensors based on giant magnetoresistive (GMR) or tunnel magnetoresistive (TMR).

[0012] Another aspect of the present invention provides a method for initializing a magnetic induction device, the method comprising: providing a magnet on a rotatable shaft; providing a magnetic induction device including at least a magnetic multi-turn sensor, wherein the magnetic induction device includes a plurality of magnetoresistive sensing elements, wherein the magnetic induction device is positioned at a first distance from the magnet such that the magnetic multi-turn sensor is operable to measure the number of turns of a magnetic field generated by the magnet; and operating an initialization mechanism configured to move the magnet and the rotatable shaft axially toward the magnetic induction device such that when the magnet is at a second distance from the magnetic induction device, the magnetic field generated by the magnet generates magnetic domain walls in the plurality of magnetoresistive elements. Attached Figure Description

[0013] This disclosure will now be described by way of example only with reference to the accompanying drawings, in which:

[0014] Figure 1 This is an example of a magnetic multi-turn sensor according to embodiments of the present disclosure;

[0015] Figure 2 This is a schematic top view of a magnetic sensor package according to an embodiment of the present disclosure;

[0016] Figure 3 These are examples of magnetic sensor systems according to embodiments of the present disclosure;

[0017] Figure 4 This is another example of a magnetic sensor system according to embodiments of the present disclosure;

[0018] Figure 5 This is another example of a magnetic sensor system according to embodiments of the present disclosure. Detailed Implementation

[0019] Magnetic multi-turn sensors can be used to monitor the number of turns of a rotating shaft. For this purpose, a magnet is typically mounted to the end of the rotating shaft, and the multi-turn sensor is sensitive to the rotation of the magnetic field as the magnet rotates with the shaft. This magnetic sensing can be applied to a wide variety of applications, such as automotive, medical, industrial control, consumer, and many other applications that require information about the position of rotating parts.

[0020] To calculate the number of turns, an xMR multi-turn sensor based on domain wall propagation in an open-loop or closed-loop helix is ​​used, typically a giant magnetoresistive (GMR) or tunneling magnetoresistive (TMR) sensor. The multi-turn sensor can then be combined with an xMR angle sensor (also known as a single-turn sensor) to determine the angular position of the rotation axis within each 360° revolution.

[0021] Figure 1 A schematic block diagram of an example magnetic sensor system 1 including an xMR multi-turn (MT) sensor 102 is shown. The magnetic sensor system 1 may also include a magnetic single-turn (ST) sensor 104, which may be a position sensor based on anisotropic magnetoresistive (AMR), giant magnetoresistive (GMR), or tunneling magnetoresistive (TMR), although it should be understood that the magnetic sensor system 1 can be implemented without the ST sensor 104 or with different types of magnetic sensors.

[0022] The sensor system 1 also includes a processing circuit 106, and an integrated circuit 100 that houses the MT sensor 102, the ST sensor 104, and the processing circuit 106. The processing circuit 106 receives the signal S from the MT sensor 102. MT 112 and processes the received signal to determine the number of turns using a turns-count decoder 108, which outputs a number of turns representing the number of turns of an external magnetic field (not shown) rotating near the MT sensor 102. Similarly, the processing circuit 106 can also receive a signal S from the ST sensor 104. ST 114. The received signal is processed using position decoder 110 to output the angular position of the external magnetic field.

[0023] Figure 2 An example representation of the magnetic stripe layout of a magnetic MT sensor 102 is shown, which includes a plurality of magnetoresistive elements 200 that may be used according to embodiments of the present disclosure. Figure 2 In the example, the magnetic strip 200 is a giant magnetoresistive (GMR) track physically arranged in an open-loop helical configuration, although it should be understood that the sensor can also be formed of tunnel magnetoresistive (TMR) material. Thus, the magnetic strip 200 has multiple segments formed by magnetoresistive elements 202 arranged in series with each other. The magnetoresistive elements 202 function as variable resistors that change resistance in response to a magnetic alignment state. One end of the magnetic strip 200 is coupled to a domain wall generator (DWG) 204. In this respect, it will be understood that the DWG 204 can be coupled to either end of the magnetic strip 200. The DWG 204 generates domain walls in response to rotation in an external magnetic field, or by some other strong external magnetic field applied outside the operating magnetic window of the sensor 102. These domain walls can then be injected into the magnetic strip 200. As the magnetic domains change, the resistance of the GMR element 202 will also change due to the resulting change in magnetic alignment.

[0024] To measure the changing resistance of the GMR element 202 during domain wall formation, the magnetic stripe 200 is electrically connected to a power supply voltage VDD 206 and ground GND 208 to apply a voltage between a pair of opposing corners. An electrical connection 210 is provided at the midpoint of the voltage source to provide a half-bridge output. Therefore, the multi-turn sensor 102 includes multiple Wheatstone bridge circuits, each half-bridge 210 corresponding to half a turn or 180° rotation of an external magnetic field. Thus, voltage measurements at electrical connections 210 can be used to measure the resistance change of the GMR element 202, which represents a change in the magnetic alignment of the free layer.

[0025] Figure 2 The example shown includes four helical windings and eight half-bridges 210, thus configured to count four turns of an external magnetic field. However, it should be understood that multi-turn sensors can have any number of helical windings, depending on the number of GMR elements. Generally, the number of turns in a multi-turn sensor can be as many as the number of helical windings. It will also be understood that the GMR elements 202 can be electrically connected in any suitable manner to provide a sensor output representing a change in magnetic alignment state. For example, the GMR elements 202 can be connected in a matrix arrangement such as described in US2017 / 0261345, which is incorporated herein by reference in its entirety. As a further alternative, each magnetoresistive element 202 can be connected individually instead of in a bridge arrangement.

[0026] As described above, the magnetic rotational speed information stored in the MT sensor 102 needs to match the physical rotational speed of the device being monitored by the MT sensor 102. Therefore, the MT sensor 102 must first be set to a known magnetic state before it can be used. To initialize the MT sensor 102, the mechanical system needs to be driven to a start or end position, and the sensor helix needs to be filled with domain walls so that the GMR element 202 provides the same sensor output. Once this is done, the MT sensor 102 will output a sequence of output signals indicating the rotational speed as the mechanical system rotates. Initialization can be accomplished by exposing the MT sensor 102 to a strong magnetic field; however, this current solution is difficult to implement once the magnetic sensor package 100 is assembled and installed in the mechanical system.

[0027] Figure 3 A first example of a magnetic sensor system 3 according to this disclosure is illustrated. A magnetic sensor package 300 including a magnetic MT sensor (not shown) is provided. It should be understood that the magnetic sensor package 300 may contain... Figure 1 The magnetic sensor system 1 shown is an MT sensor 102. A magnetic sensor package 300 is placed below a magnet 302 mounted on the end of a rotatable shaft 304, and is itself coupled to some mechanical system to be monitored. The magnet 302 is positioned above the magnetic sensor package 300 at a first distance D, which is the operating distance, whereby the magnetic field strength experienced by the magnetic sensor package 300 at this distance is within the operating magnetic window, whereby the magnetic MT sensor will accurately output rotation number information. The magnetic window is defined by a minimum magnetic flux density Bmin and a maximum magnetic flux density Bmax. Below Bmin, domain wall propagation may fail, resulting in corrupted rotation number information. Above Bmax, domain walls can nucleate, therefore, during operation, the sensor will contain erroneous rotation number information.

[0028] The magnetic sensor system 3 is provided with an initialization mechanism configured to move magnet 302 and shaft 304 axially (indicated by arrow A) toward sensor package 300. In doing so, the magnetic field experienced by the magnetic sensor package exceeds the Bmax of the magnetic MT sensor, thereby filling the MT sensor helix with domain walls and magnetizing the magnetoresistive element to its initial state. Once initialized, magnet 302 is brought back to its initial position at a first distance D above sensor package 300.

[0029] In this example, the initialization mechanism includes a spring 306 positioned between a base plate 308 and an upper plate 310, located just above the magnet 302. A rotating shaft 304 then passes through corresponding holes 305 and 307 at the centers of the base plate 308 and the upper plate 310, with the hole 305 in the base plate 308 configured to allow free rotation of the shaft 304. The base plate 308 is fixed to some external structure (not shown) such that it cannot move in the rotational or axial direction, thus providing an anchor for the initialization mechanism. In this respect, it should be understood that any suitable support structure held in a fixed axial position can serve as an anchor for the spring 306 and the upper plate 310. The upper plate 310 is fixed to the rotating shaft 304, so it can move with the shaft 304 in both the rotational and axial directions. In use, the force exerted by the upper plate 310 against the spring 306 pushes it downwards against the base plate 308, thereby compressing the spring 306 and pushing the magnet 302 downwards towards the sensor package 300, thereby increasing the magnetic field strength near the sensor package 300, thus initializing the MT sensor contained therein, as described above. Once the MT sensor has been initialized, the upper plate 310 is released, and the spring 306 then biases the upper plate 310, magnet 302, and shaft 304 back to their initial positions. In this respect, it should be understood that the upper plate 310 or shaft 304 can be pushed downwards against the force of the spring 306. For example, the shaft 304 can be pushed downwards from... Figure 3 The opposite end is driven axially. Alternatively, as another example, the upper plate 310 can be mechanically actuated by some means of pushing against its upper surface 309. Similarly, although the upper plate 310 is shown as annular, it should be understood that the upper plate 310 can be any suitable form for actuating the shaft 304 in the axial direction.

[0030] Figure 4 Another example of the magnetic sensor system 4 according to this disclosure is shown. Figure 3 As in the example shown, the magnetic sensor system 4 includes a magnetic sensor package 400, which includes a magnetic MT sensor (not shown), wherein a magnet 402 mounted on a rotation axis 404 is positioned directly above the magnetic sensor package 400. As previously described, in the initial position, the distance between the magnet 402 and the sensor package 400 is the working distance, whereby the magnetic field strength experienced by the magnetic sensor assembly 400 is within the working magnetic window where the magnetic MT sensor will accurately output the number of turns information. Figure 3Similarly, an initialization mechanism is provided, including a spring 406 connecting the base plate 408 and the upper plate 410. In this example, a key 412 is mounted to the shaft 404, which is configured to engage with an opening 414 on the base plate 408. Therefore, the upper plate 410 and the shaft 404 can only move axially downwards when the key 412 is aligned with the opening 414. This is done to ensure that the magnetic field direction is correct during initialization. In this respect, the magnetic field direction during initialization must correspond to when the rotatable shaft 404 and the mechanical system connected thereto are at the starting point (i.e., corresponding to zero revolutions) or the ending point (i.e., corresponding to maximum revolutions). Therefore, the arrangement of the key 412 and the opening 414 ensures that initialization is performed when the magnet 402 and the shaft 404 are in the desired orientation.

[0031] It is understandable that key 412 and opening 414 are one way to achieve this function, and some other suitable alignment features can be used.

[0032] Figure 5 Another example of a magnetic sensor system 5 according to this disclosure is shown. Figure 3 As in the example shown, the magnetic sensor system 5 includes a magnetic sensor package 500 containing a magnetic MT sensor, wherein a magnet 502 mounted on a rotation axis 504 is directly above the magnetic sensor package 500. As previously described, in the initial position, the distance between the magnet 502 and the sensor package 500 is the operating distance, whereby the magnetic field strength experienced by the magnetic sensor package 500 is within the operating magnetic window, in which the magnetic MT sensor will accurately output rotational speed information. Figure 3 Similarly, an initialization mechanism is provided, including a spring 506 connecting the base plate 508 and the upper plate (not visible). In this example, a locking mechanism is provided, including a locking ring 512 (e.g., a retaining ring or the like) and a locking plate 514 positioned above the upper plate, although it is understood that some other suitable fasteners or locking devices could be used to hold the shaft 504 in a fixed axial position while still allowing the shaft 504 to rotate. When the sensor system 5 is in use, the locking ring 512 is attached to the shaft 504 and abuts against the locking plate 514 to prevent the shaft 504 from moving axially, for example, due to vibrations in an external system while it is running. Any axial movement will cause a change in the magnetic field strength, which may lead to incorrect turns. Therefore, a retaining ring or the like can be used to absorb any vibrations that may disrupt the turns. Similarly, if the shaft 504 moves freely axially during use, a sudden vibration to the system may cause the sensor to initialize unexpectedly, again resulting in incorrect turns.

[0033] To initialize sensor assembly 500, locking ring 512 must be removed before axis 504 moves downward; once initialization has occurred, locking ring 512 returns to its original position.

[0034] Various modifications can be made to all the above embodiments, whether by adding, deleting and / or replacing, to provide further embodiments, wherein any and / or all of them are intended to be covered by the appended aspects.

[0035] For example, while a spring was used in the example above, it is understood that any suitable mechanism can be used to allow the magnet and shaft to move in the axial direction, and then, when using the sensor system, to hold the magnet at a position a first distance above the sensor package. For example, some other biasing device or sliding mechanism could be used instead of a spring.

[0036] Also understand, refer to Figure 5 Description of locking mechanism and reference Figure 4 The described alignment features can be used in combination.

[0037] application

[0038] Any principles and advantages discussed herein can be applied to other systems, not just those described above. Some embodiments may include a subset of the features and / or advantages set forth herein. Elements and operations of the various embodiments described above may be combined to provide further embodiments. The actions of the methods discussed herein may be performed in any suitable order. Furthermore, the actions of the methods discussed herein may be performed serially or in parallel as appropriate. Although the circuitry is shown in a particular arrangement, other equivalent arrangements are possible.

[0039] Any principles and advantages discussed herein can be implemented in conjunction with any other system, device, or method that can benefit from any of the teachings herein. For example, any principles and advantages discussed herein can be implemented in conjunction with any device that needs to correct rotational angular position data derived from a rotating magnetic field. Furthermore, such devices can include any magnetoresistive or Hall effect device capable of sensing a magnetic field.

[0040] The aspects of this disclosure can be implemented in a variety of electronic devices or systems. For example, phase correction methods and sensors implemented according to any of the principles and advantages discussed herein can be included in a variety of electronic devices and / or applications. Examples of electronic devices and applications may include, but are not limited to, components of servo systems, robots, aircraft, submarines, toothbrushes, biomedical sensing devices, and consumer electronics, such as semiconductor chips and / or packaged modules, electronic test equipment, etc. Furthermore, electronic devices may include unfinished products, including those for industrial, automotive, and / or medical applications.

[0041] Unless the context explicitly requires otherwise, throughout the specification and claims, the words “comprising,” “including,” “containing,” “having,” etc., should be interpreted in an inclusive sense, rather than an exclusive or exhaustive one. That is, in the sense of “including but not limited to.” As generally used herein, the words “coupled” or “connected” refer to two or more elements that can be directly connected or connected via one or more intermediate elements. Thus, although the various schematic diagrams shown in the figures depict exemplary arrangements of elements and components, additional intermediate elements, devices, features, or components may be present in actual embodiments (assuming that the function of the depicted circuit is not adversely affected). As used herein, the word “based on” is generally intended to cover “based on only” and “at least partially based on.” Furthermore, when used in this application, the words “here,” “on top,” “below,” and similar meanings should refer to the entire application, and not any particular part of the application. Where the context permits, singular or plural words used in the detailed description may also include the plural or singular, respectively. When referring to a list of two or more items, the word “or” is intended to cover all of the following interpretations: any item in the list, all items in the list, and any combination of items in the list. All numerical values ​​or distances provided in this article are intended to include similar values ​​within the scope of measurement error.

[0042] Although certain embodiments have been described, these embodiments are presented by way of example only and are not intended to limit the scope of this disclosure. In fact, the novel apparatuses, systems, and methods described herein can be embodied in a variety of other forms. Furthermore, various omissions, substitutions, and changes can be made to the form of the methods and systems described herein without departing from the spirit of this disclosure.

Claims

1. A magnetic sensor system, including: A magnetic induction device, the magnetic induction device comprising at least a magnetic multi-turn sensor, wherein the magnetic multi-turn sensor comprises a plurality of magnetoresistive sensing elements; A magnet mounted on a rotatable shaft is positioned at a first distance from the magnetic induction device, such that the magnetic multi-turn sensor is operable to measure the number of turns of the magnetic field generated by the magnet; and An initialization mechanism is configured to move the magnet and the rotatable shaft toward the magnetic induction device in the axial direction without requiring rotation of the rotatable shaft, such that when the magnet and the magnetic induction device are at a second distance, the magnetic field generated by the magnet produces magnetic domain walls in the plurality of magnetoresistive elements.

2. The magnetic sensor system according to claim 1, wherein the first distance is greater than the second distance.

3. The magnetic sensor system according to claim 1 or 2, wherein the magnetic multi-turn sensor has an operating window between a first magnetic field strength and a second magnetic field strength, and wherein when the magnet is at the second distance, the magnetic field strength sensed by the magnetic induction device is greater than the second magnetic field strength of the operating window.

4. The magnetic sensor system of claim 1, wherein the initialization mechanism includes a movable element configured to drive the shaft axially without requiring rotation of the rotatable shaft.

5. The magnetic sensor system according to claim 4, wherein the initialization mechanism further comprises: A support element is disposed around the rotatable shaft and held in a fixed axial position; and A biasing element, coupled between the support element and the movable element, is configured to bias the movable element to a first position, wherein when the movable element is in the first position, the magnet is at the first distance.

6. The magnetic sensor system according to claim 5, wherein the biasing element is a spring.

7. The magnetic sensor system according to claim 1 or 2, wherein the initialization mechanism includes an alignment mechanism configured to hold the magnet and the rotatable shaft at a predetermined angular position when the rotatable shaft moves axially toward the magnetic sensing device.

8. The magnetic sensor system according to claim 7, wherein the alignment mechanism comprises: A key attached to one side of the rotatable shaft; and An opening on the support element is arranged around the rotatable shaft and held in a fixed axial position, wherein the opening is configured to receive the key when the shaft moves axially toward the magnetic induction device.

9. The magnetic sensor system of claim 1 or 2, wherein the initialization mechanism includes a locking mechanism configured to hold the rotatable shaft in a first axial position such that the magnet and the magnetic sensing device maintain a first distance, wherein the locking mechanism is unlocked to allow the magnet and the rotatable shaft to move axially.

10. The magnetic sensor system of claim 9, wherein the locking mechanism includes a retaining ring.

11. The magnetic sensor system according to claim 1 or 2, wherein the magnetic multi-turn sensor is a multi-turn sensor based on giant magnetoresistive (GMR) or tunnel magnetoresistive (TMR).

12. A method for initializing a magnetic induction device, the method comprising: A magnet is provided on the rotatable shaft; A magnetic induction device is provided that includes at least a magnetic multi-turn sensor, wherein the magnetic multi-turn sensor includes a plurality of magnetoresistive sensing elements, wherein the magnetic induction device is positioned at a first distance from the magnet such that the magnetic multi-turn sensor is operable to measure the number of turns of the magnetic field generated by the magnet. and An operation initialization mechanism is configured to move the magnet and the rotatable shaft toward the magnetic induction device in the axial direction without requiring rotation of the rotatable shaft, such that when the magnet moves to a second distance from the magnetic induction device, the magnetic field generated by the magnet produces magnetic domain walls in the plurality of magnetoresistive elements.

13. The method of claim 12, wherein the first distance is greater than the second distance.

14. The method of claim 12 or 13, wherein the initialization mechanism includes a movable element configured to drive the shaft axially without requiring rotation of the shaft.

15. The method of claim 14, wherein the initialization mechanism further comprises: A support element is disposed around the rotatable shaft and held in a fixed axial position; and A biasing element, coupled between the support element and the movable element, is configured to bias the movable element to a first position, wherein when the movable element is in the first position, the magnet is at the first distance.

16. The method of claim 15, wherein the biasing element is a spring.

17. The method of claim 12 or 13, wherein the initialization mechanism further comprises an alignment mechanism configured to hold the magnet and the rotatable shaft at a predetermined angular position as the rotatable shaft moves axially toward the magnetic induction device.

18. The method of claim 17, wherein the alignment mechanism comprises: A key attached to one side of the rotatable shaft; and The opening on the support element is arranged around the rotatable axis and held in a fixed axial position; The method further includes aligning the key with the opening such that the opening accommodates the key when the shaft moves axially toward the magnetic induction device.

19. The method of claim 12 or 13, wherein the initialization mechanism further comprises a locking mechanism configured to hold the rotatable shaft in a first axial position such that the magnet and the magnetic induction device maintain a first distance, and wherein the method further comprises unlocking the locking mechanism to allow the magnet and the rotatable shaft to move axially.

20. The method of claim 19, wherein the locking mechanism comprises a retaining ring.

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