Position monitoring method using magnetic sensor system

Abstract

To provide a linear actuator device, a magnetic sensor system, and a method of use for detecting the position of a component driven by a mechanism rotatable in a linear direction.SOLUTION: A magnetic sensing device comprising a multi-turn (MT) sensor and a single turn (ST) sensor is provided within the same semiconductor package and placed in the vicinity of a rotatable mechanism. A magnet is mounted on the rotatable mechanism, such that, as the mechanism rotates, a magnetic field is generated. The MT sensor measures the number of turns of the rotating magnetic field, which is translated to the number of turns of the mechanism. The ST sensor measures the angle of the rotating magnetic field, which is translated to an angular position of the mechanism. As each turn of the mechanism is translated to a specific amount of linear motion, the amount by which the rotational mechanism has turned is proportional to the distance travelled by the driven component, and thus indicative of a linear position. Therefore, by placing a magnet and the magnetic sensing device in relation to the rotatable mechanism, with the multi-turn sensor providing the number of turns and the angle sensor providing the precise angular position within each turn, the measured rotational position can be translated to a corresponding linear position of the element being moved linearly as a result of the rotation.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to linear actuators, magnetic sensing devices and methods of use. In particular, the present disclosure relates to magnetic sensor systems and methods of use for monitoring the position of components driven by linearly rotatable mechanisms. [Background technology]

[0002] Magnetic sensor systems, including single-rotation angle sensors and multi-rotation sensors, are commonly used in applications where there is a need to monitor both the number of times a device is rotating and its precise angular position. One example is a vehicle steering wheel. Magnetic multi-rotation sensors typically include a magnetoresistive element that is susceptible to an applied external magnetic field. The resistance of the magnetoresistive element can be changed by rotating the magnetic field within the sensor's vicinity. The variation in the resistance of the magnetoresistive element is tracked to determine the number of rotations of the magnetic field, which can be converted to the number of rotations in the monitored device. Similarly, magnetic single-rotation sensors measure the field angle of a rotating magnetic field, which can be converted to the angular position of the monitored device. Summary of the Invention [Means for solving the problem]

[0003] The present disclosure provides a linear actuator apparatus, a magnetic sensor system, and a method of use for detecting the position of a component driven by a linearly rotatable mechanism. A magnetic sensing device, including both a multi-turn (MT) sensor and a single-turn (ST) sensor, is provided in the same semiconductor package and positioned around the periphery of the rotatable mechanism. A magnet is attached to the rotatable mechanism so that a rotating magnetic field is generated as the mechanism rotates. The MT sensor measures the number of rotations of the rotating magnetic field, which is converted into the number of rotations of the rotatable mechanism. The ST sensor measures the angle of the rotating magnetic field, which is converted into the angular position of the rotatable mechanism. Because each rotation of the rotatable mechanism translates into a specific amount of linear motion, the amount the rotating mechanism has rotated is proportional to the distance moved by the driving component and therefore indicates the linear position. Therefore, by positioning the magnet and magnetic sensing device relative to the rotatable mechanism, the multi-turn sensor provides the number of rotations and the angle sensor provides the precise angular position within each rotation, allowing the measured rotational position to be translated into a corresponding linear position of the element being linearly moved as a result of the rotation.

[0004] Such an arrangement provides a compact and robust device for measuring linear position and eliminates the need to install a linear position system on the linear drive component.

[0005] A first aspect of the present disclosure is a linear actuator device comprising: a first component for actuating the system in a linear direction; a rotatable mechanism configured to drive the first component in a linear direction; a magnet attached to the rotatable mechanism; at least one magnetic sensing device in the vicinity of the magnet, an angle sensor configured to detect the orientation of the magnetic field generated by the magnet as the rotatable mechanism rotates; at least one magnetic sensing device comprising: a magnetic multi-rotation sensor configured to detect the number of rotations of the magnet as the rotatable mechanism rotates; A linear actuator device is provided, wherein at least the on magnetic sensing device is configured to output a position of the first component in a linear direction based on the detected orientation of the magnetic field and the detected number of rotations.

[0006] The angle sensor and the multi-rotation sensor are preferably disposed on a first integrated circuit substrate, i.e., the multi-rotation sensor and the angle sensor are provided in the same magnetic sensor package, which can be easily installed in close proximity to the magnet without occupying a significant amount of space. It is possible.

[0007] The at least one magnetic sensing device may further comprise processing means for determining the position of the first component in a linear direction.

[0008] The angle sensor is preferably configured to detect the orientation of the magnetic field over the range of 0° to 180°, i.e., the angle sensor determines the absolute angular position within each half rotation.

[0009] The angle sensor may be one of an anisotropic magnetoresistive (AMR) based single rotation sensor, a giant magnetoresistive (GMR) based single rotation sensor, a tunnel magnetoresistive (TMR) based single rotation sensor, a Hall effect sensor, and an inductive sensor.

[0010] The multi-turn sensor can be a giant magnetoresistance (GMR) based multi-turn sensor or a tunneling magnetoresistance (TMR) based multi-turn sensor.

[0011] A multi-turn sensor may comprise multiple magnetoresistive elements electrically connected in series and physically laid out in a spiral configuration.

[0012] In such a case, the multi-rotation sensor further comprises a matrix of electrical connections arranged to electrically connect magnetic resistance elements of the plurality of magnetic resistance elements to other magnetic resistance elements of the plurality of magnetic resistance elements, the matrix being at least 3x3.

[0013] The rotatable mechanism may include a first cylindrical gear, and the first component may include a linear gear configured to cooperate with the first cylindrical gear such that rotation of the first cylindrical gear translates the linear gear in a linear direction. For example, each gear may include teeth that cooperate together, thereby providing a rack and pinion arrangement.

[0014] The rotatable mechanism may further comprise a second cylindrical gear configured to cooperate with the first cylindrical gear such that rotation of the second cylindrical gear causes corresponding rotation of the first cylindrical gear.

[0015] In such a case, a magnet may be mounted in association with the first cylindrical gear or the second cylindrical gear, such that the magnet rotates with one of the gears, thereby generating a rotating magnetic field, and the magnetic sensing device therefore monitors the rotation of the gear to which the magnet is mounted.

[0016] The rotatable mechanism may include a threaded screw and a cylindrical gear, where the threaded screw is configured to cooperate with the cylindrical gear such that rotation of the threaded screw causes rotation of the cylindrical gear. For example, the rotatable mechanism may be a worm drive arrangement including a worm and a worm gear.

[0017] In such an arrangement, the first component may then comprise a linear gear configured to cooperate with the cylindrical gear such that rotation of the cylindrical gear translates the linear gear in a linear direction.

[0018] In other arrangements, the rotatable mechanism may include a threaded shaft, and the first component includes an annular portion disposed about and configured to engage the threaded shaft such that rotation of the threaded shaft causes the annular portion to translate linearly along the threaded shaft. One example of such an arrangement is a lead screw with a nut that moves along the lead screw when rotated.

[0019] In some cases, the threaded shaft may further comprise a gear arrangement configured to drive rotation of the threaded shaft. In such cases, the magnet may be attached to the gear arrangement.

[0020] The magnets can be single-pole pair magnets or multi-pole magnets.

[0021] If the magnet is a multi-pole ring magnet, the at least one magnetic sensing device may be located at a first location adjacent the outer periphery of the multi-pole magnet and / or at a second location in front of the multi-pole magnet aligned with the pole pairs.

[0022] The linear actuator device may further comprise a motor configured to drive the rotatable mechanism.

[0023] The linear actuator device may further comprise an electromagnet for initializing the angle sensor and the multi-rotation sensor.

[0024] The linear actuator apparatus may further include a protective shield formed around the magnet and magnetic sensing device, for example, the protective shield may comprise a ferromagnetic material to protect the sensing device from stray magnetic fields that may cause erroneous readings.

[0025] The linear actuator apparatus may further comprise a linear sensor system, for example the linear sensor system may comprise an incremental linear track including a first number of magnetic poles and a further magnetic sensing device configured to count the first number of magnetic poles.

[0026] A second aspect of the present disclosure is a method of position monitoring using a magnetic sensing device, wherein a magnet is attached to a rotatable mechanism configured to actuate a first component in a linear direction, the method comprising: using an angle sensor to detect the orientation of a magnetic field generated by the magnet as the rotatable mechanism rotates; using a multi-turn sensor to detect the number of turns of the magnet as the rotatable mechanism turns; determining a position of the first component in a linear direction based on the detected orientation and the detected number of rotations.

[0027] Determining the position of the first component in the linear direction may include determining an amount of rotation in the first direction by the rotatable mechanism and determining a distance traveled by the first component in the linear direction based on the determined amount of rotation. In this regard, the amount of rotation by the rotatable mechanism is proportional to the distance traveled by the first component, and thus the measured rotation may directly translate to a linear position.

[0028] The angle sensor and the multi-rotation sensor are preferably disposed on a first integrated circuit substrate.

[0029] Detecting the orientation of the magnetic field preferably includes detecting the orientation of the magnetic field over a range of 0° to 180°.

[0030] The method may further include initializing the angle sensor and / or the multi-rotation sensor when the first component is in the start position.

[0031] A further aspect of the present disclosure is a processor; and a computer-readable medium storing one or more instructions, which, when executed, are arranged to cause a processor to perform the above-described method.

[0032] A further aspect of the present disclosure is a magnetic sensor system for monitoring position, comprising: a magnet attached to a rotatable mechanism, the rotatable mechanism configured to actuate the first component in a linear direction; and at least one magnetic sensing device in the vicinity of the magnet, an angle sensor configured to detect the orientation of the magnetic field generated by the magnet as the rotatable mechanism rotates; at least one magnetic sensing device comprising: a magnetic multi-rotation sensor configured to detect the number of rotations of the magnet as the rotatable mechanism rotates; A magnetic sensor system is provided, wherein at least the on magnetic sensing device is configured to output a position of the first component in a linear direction based on the detected orientation of the magnetic field and the detected number of rotations.

[0033] The angle sensor and the multi-rotation sensor are preferably disposed on a first integrated circuit substrate.

[0034] The at least one magnetic sensing device may further comprise processing means for determining the position of the first component in a linear direction.

[0035] The angle sensor is preferably configured to detect the orientation of the magnetic field over the range of 0° to 180°. [Brief explanation of the drawings]

[0036] The present disclosure is now described, by way of example only, with reference to the accompanying drawings in which: [Figure 1] 1A-1C are schematic top views of a multi-rotation sensor and a single-rotation sensor according to an embodiment of the present disclosure. [Figure 2] 1 is an example of a magnetic multi-rotation sensor according to an embodiment of the present disclosure. [Figure 3A] 1 illustrates an example of a magnetic sensor system according to an embodiment of the present disclosure. [Figure 3B] 1 illustrates an example of a magnetic sensor system according to an embodiment of the present disclosure. [Figure 4]1 illustrates another example of a magnetic sensor system according to an embodiment of the present disclosure. [Figure 5] 1 illustrates a further example of a magnetic sensor system according to an embodiment of the present disclosure. [Figure 6A] 1 illustrates a further example of a magnetic sensor system according to an embodiment of the present disclosure. [Figure 6B] 1 illustrates a further example of a magnetic sensor system according to an embodiment of the present disclosure. [Figure 7A] 1 illustrates a further example of a magnetic sensor system according to an embodiment of the present disclosure. [Figure 7B] 1 illustrates a further example of a magnetic sensor system according to an embodiment of the present disclosure. [Figure 8A] 1 illustrates a further example of a magnetic sensor system according to an embodiment of the present disclosure. [Figure 8B] 1 illustrates a further example of a magnetic sensor system according to an embodiment of the present disclosure. [Figure 9A] 1 illustrates a further example of a magnetic sensor system according to an embodiment of the present disclosure. [Figure 9B] 1 illustrates a further example of a magnetic sensor system according to an embodiment of the present disclosure. [Figure 10] 1 illustrates a further example of a magnetic sensor system according to an embodiment of the present disclosure. [Figure 11] 1 illustrates a further example of a magnetic sensor system according to an embodiment of the present disclosure. [Figure 12] 1 illustrates a further example of a magnetic sensor system according to an embodiment of the present disclosure. [Figure 13A] 1 illustrates a further example of a magnetic sensor system according to an embodiment of the present disclosure. [Figure 13B] 1 illustrates a further example of a magnetic sensor system according to an embodiment of the present disclosure. [Figure 14A] 1 illustrates a further example of a magnetic sensor system according to an embodiment of the present disclosure. [Figure 14B] 1 illustrates a further example of a magnetic sensor system according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0037] Magnetic multi-turn and single-turn sensors can be used to monitor the rotation count and angular position of a rotating shaft. Such magnetic sensing can be applied to a variety of different applications, such as automotive applications, medical applications, industrial control applications, consumer applications, and a host of other applications that require information about the position of rotating components.

[0038] The present disclosure provides a linear actuator apparatus, a magnetic sensor system, and a method of use for detecting the position of a linearly rotatable mechanism, such as a component driven by a rack-and-pinion arrangement or a nut on a lead screw. A magnetic sensing device, including both a multi-turn (MT) sensor and a single-turn (ST) sensor, is provided in the same semiconductor package and positioned around the periphery of the rotatable mechanism. A magnet is also attached to the rotatable mechanism so that a rotating magnetic field is generated as the mechanism rotates. The MT sensor measures the number of rotations of the rotating magnetic field, which is converted into the number of rotations of the rotatable mechanism. The ST sensor measures the angle of the rotating magnetic field, which is converted into the angular position of the rotatable mechanism. Because each rotation of the rotatable mechanism converts into a specific amount of linear motion, the amount the rotating mechanism has rotated is proportional to the distance traveled and therefore indicates the linear position. Therefore, by positioning the magnet and magnetic sensing device relative to the rotatable mechanism, the multi-turn sensor provides the number of rotations and the angle sensor provides the precise angular position within each rotation, allowing the measured rotational position to be translated into a corresponding linear position of the element being linearly moved as a result of the rotation.

[0039] Such an arrangement provides a compact and robust device for measuring linear position and eliminates the need to install a linear position system on the linear drive component.

[0040] FIG. 1 illustrates a schematic block diagram of an exemplary magnetic sensing device 1 including a multi-turn (MT) sensor 102 and a single-turn (ST) sensor 104 provided in a single semiconductor package. The MT sensor 102 is preferably a giant magnetoresistance (GMR) or tunneling magnetoresistance (TMR)-based MT sensor. The ST sensor 104 can be any magnetic ST sensor, such as an anisotropic magnetoresistance (AMR), giant magnetoresistance (GMR), or tunneling magnetoresistance (TMR)-based sensor, a Hall sensor, or an inductive sensor. Preferably, the ST sensor 104 is an AMR single-turn sensor configured to measure angular position over a 180° range, thereby providing accurate angular position within each half-turn counted by the MT sensor 102. Such an arrangement is simpler to implement and generally more robust and tolerant to disturbances due to stray magnetic fields, etc. Generally, 180° AMR single-turn sensors have higher accuracy than other magnetic angle sensors. For example, tunneling magnetoresistance (TMR) or giant magnetoresistance (GMR) based sensors often experience hysteresis issues that lead to different results for clockwise and counterclockwise rotation.

[0041] The sensing device 1 also includes a processing circuit 108 and an integrated circuit 100 in which the MT sensor 102, the ST sensor 104, and the processing circuit 108 are arranged. The processing circuit 106 receives a signal S from the MT sensor 102. MT 112 and processes the received signal to determine a rotation count using a rotation count decoder 108, which outputs a rotation count representing the number of rotations of an external magnetic field (not shown) rotating around the MT sensor 102, for example, a magnetic field generated by a magnet attached to a rotatable mechanism that drives another element in a linear direction. Similarly, the processing circuit 106 receives a signal S from the ST sensor 104. ST 114 and processes the received signals using an angular decoder 110 to output the angular position of the external magnetic field. As described in more detail below, the rotation count and angular position may then be input to a position decoder 116 that is configured to calculate the linear position of the drive element based on the amount the rotatable mechanism has rotated.

[0042] FIG. 2 shows an example of a magnetic strip 202 layout representation of a magnetic multi-rotation sensor 2, shown here on an integrated circuit 200, which may provide the MT sensor 102 shown in FIG.

[0043] In FIG. 2 , the magnetic strip 202 includes multiple magnetoresistive elements 204, preferably GMR-based magnetoresistive elements or, alternatively, TMR-based magnetoresistive elements. In this example, the magnetic strip 202 is a GMR-based magnetoresistive track physically laid out in a spiral configuration. Thus, the magnetic strip 202 has multiple segments formed by the magnetoresistive elements 204 arranged in series with one another. The magnetoresistive elements 204 function as variable resistors that change resistance depending on the magnetic alignment state. The ends of the magnetic strip 202 are coupled to domain wall generators (DWGs) 206, and it is understood that the DWGs 206 may be coupled to either end of the magnetic strip 202. The DWGs 206 generate domain walls in response to the rotation of an external magnetic field or the application of some other strong external magnetic field within the operating magnetic window of the sensor 2. These domain walls are then injected into the magnetic strip 202, and as the magnetic domains change, the resistance of the magnetoresistive elements 204 also changes due to the resulting change in magnetic alignment.

[0044] To measure the changing resistance of the magnetoresistive element 204 as the domain walls are created, the magnetic strip 202 is electrically connected to a supply voltage VDD 208 and ground GND 210 to apply a voltage between pairs of opposite corners. An electrical connection 212 is provided at the middle corner of the voltage supply to provide a half-bridge output. The multi-rotation sensor 2 thus comprises multiple Wheatstone bridge circuits, with each half-bridge 212 corresponding to a half rotation or 180 degrees of rotation of the external magnetic field. The voltage measurement at the electrical connection 212 can therefore be used to measure the change in resistance of the magnetoresistive element 204. The magnetoresistive element 204 can therefore be used to determine the number of rotations in the magnetic field, for example, by outputting the voltage measurement to the rotation count decoder 108.

[0045] The example shown in FIG. 2 includes four spiral windings and eight half bridges 212 and is therefore configured to count four full rotations of the external magnetic field. However, it is understood that a multi-rotation sensor may have any number of spiral windings, depending on the number of magnetoresistive elements 204. Generally, a multi-rotation sensor can count as many rotations as there are spiral windings. It is also understood that the magnetoresistive elements 204 can be electrically connected in any suitable manner to provide a sensor output representative of changes in magnetic alignment. For example, the magnetoresistive elements 204 can be connected in a matrix arrangement, as described in US 2017 / 0261345, the entire contents of which are incorporated by reference herein.

[0046] Alternatively, the MT sensor 102 can be a closed-loop spiral, with the magnetoresistive elements of the inner and outer spiral windings connected together to form a continuous spiral. Such an arrangement provides the effect of multiple spirals connected together, which allows for counting a very large number of revolutions.

[0047] 3A-3B illustrate a first example of a system for monitoring the linear position of a component driven by a rotatable mechanism using a magnetic sensing device. FIG. 3A provides a side view of the system 3, and FIG. 3B shows a front view. In this example, a toothed rack 302 is driven linearly by a toothed gear 300 rotatable by a rotating shaft 304, thereby forming a rack-and-pinion linear actuator. The teeth of the gear 300 and the rack 302 cooperate, so that as the gear 300 rotates, the rack 302 moves linearly in a corresponding manner, and each degree of rotation by the gear 300 causes the rack 302 to translate a proportional distance in a linear direction. For example, when the gear 300 rotates in a first direction A1, the rack is linearly translated in a first direction B1. If the gear 300 then rotates in the opposite direction A2, the rack 302 is then linearly translated in the opposite direction B2. In this manner, the rotation of gear 300 can therefore be used to drive rack 302, or vice versa, which in turn can drive some other device or system, for example, an elevator or a sliding door.

[0048] A single-pole pair magnet 306 is attached to the end of a rotating shaft 304 so that a rotating magnetic field is generated. A magnetic sensing device 308, which may be magnetic sensing device 1 described with reference to Figure 1, is located around the periphery of magnet 306. In all examples described herein, it will be understood that the magnetic sensing device may be attached to some other structure, not shown, such that it is held in a fixed location relative to the rotating magnet.

[0049] As previously mentioned, rack 302 moves linearly as gear 300 rotates in one direction or the other. Magnetic sensing device 308 measures the rotating magnetic field generated by magnet 306 to determine the amount gear 300 has rotated in either direction by counting the number of rotations made and the absolute angular position within each rotation, or preferably each half rotation, which is then used to determine the linear position of toothed rack 302. For example, gear 300 may be rotated three full rotations in a clockwise direction as measured by MT sensor 102 and an additional 45° as measured by ST sensor 104. Based on these measurements and the proportional relationship between the respective movements of gear 300 and rack 302, which may be based, for example, on the size and number of cooperating teeth, the distance traveled by rack 302 and, therefore, its linear position, can be determined, for example, by position decoder 116. If gear 300 then rotates back 360° counterclockwise, MT sensor 102 will measure only two full rotations, and the measured linear position of rack 302 will be adjusted accordingly, since it is known how far rack 302 travels per rotation of gear 300.

[0050] This arrangement provides a simple and accurate way to measure the linear position of the rack 302 without having to install a linear sensing system on the rack itself. Furthermore, by co-locating a single sensor package 308 containing both the MT and ST sensors, no calibration is required to align the readings of the two sensors because both sensors are measuring the same rotating magnetic field.

[0051] The rotating shaft 304 that drives the gear 300 may be rotated using any suitable means, for example, using a motor 400, as shown in FIG.

[0052] The above-described arrangement can also be supplemented with a second magnetic sensing device, as shown in FIG. 5 . Here, a second magnetic sensing device 502, which may comprise a Hall sensor or a magnetoresistive sensor, is attached to the rack 302 for movement therewith. An incremental linear track 500 containing alternating north and south poles is provided parallel to the rack 302. As the rack 302 moves linearly, the second magnetic sensing device 502 detects the magnetic poles and incrementally measures the change in position as it moves along the track 502. To accurately measure linear position, synchronization is required so that one revolution corresponds to one or half cycles of movement on a linear scale. This arrangement can be used in addition to or instead of the ST sensor of the first magnetic sensing device 308. While a magnetic track 500 and sensor 502 are described, it is understood that several other linear encoders, such as optical encoders, can also be used.

[0053] 6A-6B illustrate another example of a system for monitoring the linear position of a component driven by a rotatable mechanism using a magnetic sensing device.

[0054] In this example, the magnet 406 is attached to the end of a first rotating shaft 604a, which is driven by a motor 601, although it will be understood that any suitable drive means may be used, which in turn drives a first toothed gear 600A. The teeth of the first gear 600A are arranged to cooperate with the teeth of a second toothed gear 600B, which may be attached to a second shaft 604B for further structural support. It will also be understood that the magnet 606 and magnetic sensing device 608 may alternatively be disposed on the second shaft 604B so as to rotate with the second gear 600B. The second gear 600B is then arranged to cooperate with the teeth of a toothed rack 602 to cause its linear movement. As described above with reference to the example of Figures 3A-B, as shaft 604A rotates, first gear 600A rotates, causing corresponding rotation in the opposite direction of second gear 600B, which in turn causes rack 602 to translate a corresponding distance in a linear direction.

[0055] As mentioned above, the magnetic sensing device 608 is positioned around the magnet 606, thereby measuring the magnetic field generated by the magnet 606 as the shaft 604A rotates. Based on the rotating magnetic field, the magnetic sensing device 608 measures the rotating magnetic field generated by the magnet 606 to determine the number of rotations and absolute angular positions of the first and second gears 600A, 600B, which can then be translated to the linear position of the rack 602 as described above.

[0056] 7A-7B illustrate a further example of a system for monitoring the linear position of a component driven by a rotatable mechanism using a magnetic sensing device, similar to that of FIGS. 3A-3B , except that in this example, a multi-pole magnet 706 is mounted on the shaft 704. The use of the multi-pole magnet 706 helps increase the resolution of the sensing devices 708A, 708B, and specifically, the ST sensor 104, by providing multiple rotations of the magnetic field for each rotation of the gear 700. In such a case, the magnetic sensing device 708 may be mounted in two different positions, shown here as 708A and 708B. In the first position, the magnetic sensing device 708A is mounted in line with the magnet 706, such that the magnet 706 is positioned adjacent its outer periphery. While the sensing device 708A is shown above the magnet 706 in this example, it will be understood that it may be located anywhere around the periphery of the magnet 706. In the second position, the magnetic sensing device 708B is mounted in front of the magnet 706, such that the magnet 706 is aligned with the pole pairs. Again, it is understood that the magnetic sensing device 708B can be located at any radial position. At these locations, the magnetic sensing devices 708A, 708B remain within the magnetic window of the magnetic field, and changes in the magnetic field angle are directly proportional to changes in the angle of the gear 700. Alternatively, the system can include two magnetic sensing devices 708A, 708B located at two different locations, as described above, with each sensing device 708A, 708B including an MT sensor and an ST sensor within a single semiconductor package. This can improve fault tolerance in the event of a sensor failure within the package.

[0057] 8A-8B illustrate a further example of a system for monitoring the linear position of a component driven by a rotatable mechanism using a magnetic sensing device. In this example, the rotatable mechanism is a worm drive arrangement in which a magnet 806 and magnetic sensing device 808 are attached to the end of a threaded screw 800A, also referred to as a "worm," which rotates to drive a cylindrical gear 800B (also referred to as a "worm gear"), as described above. The worm gear 800B drives a toothed rack (not shown) or similar linear motion. The magnetic sensing device 808 measures the rotating magnetic field as the worm 800A rotates, thereby measuring the amount of rotation by the worm 800A. Each degree of rotation of the worm 800A causes a proportional amount of rotation by the worm gear 800B, which in turn causes a proportional amount of linear movement by the drive component, so that the measured rotational position can be converted to a linear position.

[0058] 9A-9B illustrate another example of a system for monitoring the linear position of a component driven by a rotatable mechanism using a magnetic sensing device. In this example, a nut 902 is driven linearly by a rotating shaft having a lead screw 900 that is rotatable by a rotating shaft 904. The nut 902 may have internal ball screw threads that cooperate with the threads of the lead screw 900 such that as the lead screw 900 rotates, the nut 902 moves linearly along the lead screw 900, with each degree of rotation of the lead screw 900 causing the nut 902 to translate a proportional distance in the linear direction.

[0059] As previously described, a single-pole pair magnet 906 is attached to the end of a rotating shaft 904 so that a rotating magnetic field is generated. A magnetic sensing device 908, which may be the magnetic sensing device 1 described with reference to FIG. 1, is located around the magnet 906.

[0060] As previously mentioned, the nut 902 moves linearly as the lead screw 900 rotates in one direction or the other. The magnetic sensing device 908 measures the rotating magnetic field generated by the magnet 906 to determine the amount the lead screw 900 has rotated in either direction by counting the number of rotations made and the absolute angular position within each rotation, or preferably each half rotation, which is then used to determine the linear position of the nut 902. For example, the lead screw 900 may be rotated two full rotations in the clockwise direction as measured by the MT sensor 102 and an additional 15° as measured by the ST sensor 104. Based on these measurements and the proportional relationship between the respective movements of the lead screw 900 and the nut 902, it may be determined, for example, by the position decoder 116, that the nut 902 has traveled 20 mm from left to right.

[0061] As previously mentioned, this provides a simple and very accurate way to measure the linear position of the nut 902 without having to install a linear sensing system on the nut itself. Furthermore, by co-locating a single sensor package 908 containing both the MT and ST sensors, no calibration is required to align the readings of the two sensors because both sensors are measuring the same rotating magnetic field.

[0062] As shown by way of example in FIG. 10 , the rotatable shaft 904 driving the lead screw 900 may be rotated by a motor 1000 or some other suitable means. In another arrangement, shown in FIG. 11 , a motor 1100 is arranged to drive the shaft 904 via a gearbox 1102 or some other power transmission. In such an arrangement, a magnet 1106 may be attached to the shaft of the motor 1100 with a peripherally located magnetic sensing device 1108 to measure the rotation of the motor 1100. This magnet 1106 and magnetic sensing device 1108 may be provided instead of, or in addition to, the magnet 906 and sensor 908 located on the lead screw 900. As previously described, the measured rotation of the motor 1100 causes a corresponding rotation of the lead screw 900, which in turn causes a corresponding linear movement by the nut 902. The amount of rotation by the motor 1100 measured by the magnetic sensing device 1108 may therefore be converted to a linear position of the nut 902.

[0063] The arrangement described above with reference to FIGS. 9A-9B can also be supplemented with a second magnetic sensing device, as illustrated in FIG. 12. Here, a second magnetic sensing device 1202, which may comprise a Hall sensor or a magnetoresistive sensor, is attached to the nut 902 in some manner so that it moves with the nut 902. An incremental linear track 1200 containing alternating north and south poles is provided parallel to the lead screw 900. As the nut 902 moves linearly, the second magnetic sensing device 1202 detects the magnetic poles and incrementally measures the change in position as it moves along the track 1202. To accurately measure linear position, synchronization is required so that one revolution corresponds to one or half cycles of movement on a linear scale. This arrangement can be used in addition to or instead of the ST sensor of the first magnetic sensing device 908. While a magnetic track 1200 and sensor 1202 are described, it is understood that some other linear encoder, such as an optical encoder, could also be used.

[0064] 13A-B illustrate another example of a system for monitoring the linear position of a component driven by a rotatable mechanism using a magnetic sensing device.

[0065] In this example, the magnet 1306 is attached to the end of a first toothed gear 1310A. The teeth of the first gear 1310A are arranged to cooperate with the teeth of a second toothed gear 1310B, which is attached to the shaft 1304 of the lead screw 1300, so that the first toothed gear 1310A, the second toothed gear 1310B, and the lead screw 1300 all rotate together. It will be understood that the first toothed gear 1310A may be driven by some other means, such that rotation of the first toothed gear 1310A drives rotation of the second toothed gear 1310B and the lead screw 1300. Alternatively, the shaft 1304 of the lead screw 1300 may be driven by some other means, such as a motor, so that rotation of the lead screw 1300 drives rotation of the first and second gears 1310A, 1310B.

[0066] As described above, the magnetic sensing device 1308 is positioned around the magnet 1306, thereby measuring the magnetic field generated by the magnet 1306 as the first toothed gear 1310A rotates. Based on the rotating magnetic field, the magnetic sensing device 1308 measures the rotating magnetic field generated by the magnet 1306 to determine the number of rotations and absolute angular position of the first and second gears 600A, 600B, which can then translate the first and second gears 1300A, 1300B and the lead screw 1300 to a linear position of the nut 902, as described above.

[0067] 14A-B illustrate a further example of a system for monitoring the linear position of a component driven by a rotatable mechanism using a magnetic sensing device, similar to that of FIGS. 9A-B, but in this example, a multi-pole magnet 1406 is mounted on the shaft 1404. The use of the multi-pole magnet 1406 helps increase the resolution of the sensing devices 1408A, 1408B, and specifically, the ST sensor 104, because it provides multiple rotations of the magnetic field for each rotation of the lead screw 1400. In such a case, the magnetic sensing device 1408 may be mounted in two different positions, shown here as 1408A and 1408B. In the first position, the magnetic sensing device 1408A is mounted in line with the magnet 1406, such that the magnet 1406 is positioned adjacent its outer periphery. In this example, the sensing device 1408A is shown above the magnet 1406, but it will be understood that it may be located anywhere around the periphery of the magnet 1406. In the second position, the magnetic sensing device 1408B is mounted in front of the magnet 1406 so that the magnet 1406 is aligned with the pole pair. Again, it is understood that the magnetic sensing device 1408B can be located at any radial position. In these positions, the magnetic sensing devices 1408A, 1408B remain within the magnetic window of the magnetic field, and changes in the magnetic field angle are directly proportional to changes in the angle of the gear 1400. Alternatively, the system can include two magnetic sensing devices 1408A, 1408B located at two different locations, as described above, with each sensing device 1408A, 1408B comprising an MT sensor and an ST sensor within a single semiconductor package. This can improve fault tolerance in the event of a sensor failure within the package.

[0068] It will be appreciated that the methods and systems for measuring linear position described herein may be applied to several different applications in which a component is driven in a linear direction by a rotary mechanism, including, but not limited to, clutch actuators, transmission actuators, seat position / rotation, power sliding doors, sunroofs, power sliding windows, tilt actuators, active suspension forklift steering (tilt, position, extension), window blinds, window shutters, printers, elevators, machining equipment (lathes, milling, wire cut), 3D printers, and dispensing / injection equipment.

[0069] The use of magnetic sensing devices and magnet arrangements has significant advantages in that it provides a significantly smaller, less complex and cheaper system compared to existing linear measurement systems currently used in such applications. Furthermore, magnetic sensors do not require power to measure rotational speed and angular position and can therefore continue to output measurements if power is lost elsewhere.

[0070] Various modifications may be made to all of the above embodiments by way of addition, deletion, and / or substitution to provide further embodiments, any and / or all of which are intended to be encompassed by the appended claims.

[0071] For example, in any of the above arrangements, a shield in the form of a cap or the like made from a ferromagnetic material may be placed around the magnet and magnetic sensing device to protect against stray magnetic fields that may interfere with rotation counting and angle measurement.

[0072] In another example, the system may be provided with an electromagnet that initializes the magnetic sensing device when the rotatable mechanism and drive element are in a starting position, e.g., when the drive element is in one of its end positions or in an intermediate position. Preferably, the electromagnet is located near the MT sensor to align all of the magnetizations of the magnetoresistive elements in one direction. That is, when the drive element is in its starting position, the electromagnet may initialize the magnetic sensor so that this position corresponds to a zero rotation count reading by the MT sensor and a zero degree angle reading by the ST sensor. This then provides a starting point from which the rotation count and angle are measured as the rotatable mechanism rotates to linearly drive the element.

Claims

1. 1. A linear actuator device comprising: a first component for operating the system in a linear direction; a rotatable mechanism configured to drive the first component in the linear direction; a magnet attached to the rotatable mechanism; at least one magnetic sensing device in the periphery of the magnet, an angle sensor configured to detect the orientation of the magnetic field generated by the magnet as the rotatable mechanism rotates; at least one magnetic sensing device comprising: a magnetic multi-rotation sensor configured to detect the number of rotations of the magnet as the rotatable mechanism rotates; the at least one magnetic sensing device is configured to output a position of the first component in the linear direction based on the detected orientation of the magnetic field and the detected number of rotations.

2. 2. The linear actuator device of claim 1, wherein the angle sensor and the multi-rotation sensor are disposed on a first integrated circuit board.

3. 3. The linear actuator arrangement of claim 1 or 2, wherein the at least one magnetic sensing device further comprises processing means for determining the position of the first component in the linear direction.

4. 4. The linear actuator device of claim 1, wherein the angle sensor is configured to detect the orientation of the magnetic field over a range of 0° to 180°.

5. 5. The linear actuator device of claim 1, wherein the angle sensor is one of an anisotropic magnetoresistance (AMR) based single rotation sensor, a giant magnetoresistance (GMM) based single rotation sensor, a tunneling magnetoresistance (TMR) based single rotation sensor, a Hall effect sensor, and an inductive sensor.

6. 6. The linear actuator device according to claim 1, wherein the multi-turn sensor is a giant magnetoresistance (GMR) based multi-turn sensor or a tunnel magnetoresistance (TMR) based multi-turn sensor.

7. 7. The linear actuator device of claim 1, wherein the multi-turn sensor comprises a plurality of magnetoresistive elements electrically connected in series and physically laid out in a spiral configuration.

8. 8. The linear actuator device of claim 7, wherein the multi-rotation sensor further comprises a matrix of electrical connections arranged to electrically connect magnetoresistive elements of the plurality of magnetoresistive elements to other magnetoresistive elements of the plurality of magnetoresistive elements, the matrix being at least 3x3.

9. 9. The linear actuator device of claim 1, wherein the rotatable mechanism comprises a first cylindrical gear and the first component comprises a linear gear configured to cooperate with the first cylindrical gear, such that rotation of the first cylindrical gear translates the linear gear in a linear direction.

10. 10. The linear actuator device of claim 9, wherein the rotatable mechanism further comprises a second cylindrical gear configured to cooperate with the first cylindrical gear such that rotation of the second cylindrical gear causes corresponding rotation of the first cylindrical gear.

11. The linear actuator device of claim 10 , wherein the magnet is mounted in association with the first cylindrical gear or the second cylindrical gear.

12. 9. The linear actuator device of any one of claims 1 to 8, wherein the rotatable mechanism comprises a threaded screw and a cylindrical gear, the threaded screw configured to cooperate with the cylindrical gear, such that rotation of the threaded screw causes rotation of the cylindrical gear.

13. 13. The linear actuator device of claim 12, wherein the first component comprises a linear gear configured to cooperate with the cylindrical gear such that rotation of the cylindrical gear translates the linear gear in a linear direction.

14. 9. The linear actuator device of claim 1, wherein the rotatable mechanism comprises a threaded shaft and the first component comprises an annular portion disposed around and configured to engage the threaded shaft, such that rotation of the threaded shaft causes the annular portion to translate linearly along the threaded shaft.

15. 15. The linear actuator device of claim 14, wherein the threaded shaft further comprises a gear arrangement configured to drive the rotation of the threaded shaft.

16. 16. A linear actuator device according to any one of claims 1 to 15, wherein the magnet is a single-pole pair magnet or a multi-pole magnet.

17. 17. The linear actuator apparatus of claim 1, wherein the magnet is a multi-pole ring magnet and the at least one magnetic sensing device is located at a first position adjacent an outer periphery of the multi-pole magnet and / or at a second position in front of the multi-pole magnet aligned with a pole pair.

18. 18. The linear actuator device of claim 1, further comprising a motor configured to drive the rotatable mechanism.

19. 19. The linear actuator device of claim 1, further comprising an electromagnet for initializing the angle sensor and multi-rotation sensor.

20. 20. The linear actuator apparatus of claim 1, further comprising a protective shield formed around the magnet and magnetic sensing device.

21. 21. The linear actuator device of claim 20, wherein the protective shield comprises a ferromagnetic material.

22. 22. A linear actuator device according to any one of claims 1 to 21, further comprising a linear sensor system.

23. the linear sensor system is an incremental linear track including a first number of magnetic poles; 23. The linear actuator apparatus of claim 22, comprising: a further magnetic sensing device configured to count the first number of magnetic poles.

24. 1. A method of position monitoring using a magnetic sensing device, wherein a magnet is attached to a rotatable mechanism configured to actuate a first component in a linear direction, the method comprising: using an angle sensor to detect the orientation of the magnetic field generated by the magnet as the rotatable mechanism rotates; using a multi-rotation sensor to detect the number of rotations of the magnet as the rotatable mechanism rotates; determining a position of the first component in the linear direction based on the detected orientation and the detected number of rotations.

25. Determining the position of the first component in the linear direction determining an amount of rotation in a first direction by the rotatable mechanism; and determining a distance traveled by the first component in the linear direction based on the determined amount of rotation.

26. 26. The method of claim 24 or 25, wherein the angle sensor and the multi-rotation sensor are disposed on a first integrated circuit substrate.

27. 27. The method of any one of claims 24 to 26, wherein detecting the orientation of the magnetic field comprises detecting the orientation of the magnetic field over a range from 0° to 180°.

28. The method of any one of claims 24 to 27, further comprising initializing the angle sensor and / or multi-rotation sensor when the first component is in a start position.

29. a processor; A computer readable medium storing one or more instructions, which, when executed, are arranged to cause said processor to perform the method of any one of claims 24 to 28.

30. 1. A magnetic sensor system for monitoring position, comprising: a magnet attached to a rotatable mechanism, the rotatable mechanism configured to actuate the first component in a linear direction; and at least one magnetic sensing device in the vicinity of the magnet, an angle sensor configured to detect the orientation of the magnetic field generated by the magnet as the rotatable mechanism rotates; at least one magnetic sensing device comprising: a magnetic multi-rotation sensor configured to detect the number of rotations of the magnet as the rotatable mechanism rotates; the at least one magnetic sensing device configured to output a position of the first component in the linear direction based on the detected orientation of the magnetic field and the detected number of rotations.

31. 31. The magnetic sensor system of claim 30, wherein the angle sensor and the multi-rotation sensor are disposed on a first integrated circuit substrate.

32. 32. The magnetic sensor system of claim 30 or 31, wherein the at least one magnetic sensing device further comprises processing means for determining the position of the first component in the linear direction.

33. The magnetic sensor system of any one of claims 30 to 32, wherein the angle sensor is configured to detect the orientation of the magnetic field over a range of 0° to 180°.

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