Patent Description:
As illustrated in <FIG>, related art sensor systems <NUM> utilized for navigation, such as Attitude and Heading Reference Systems (AHRS) and Inertial Navigation Systems (INS), typically include a linear stack of discrete, uniaxial sensors. The related art sensor system <NUM> illustrated in <FIG> includes a housing or a chassis <NUM> housing a linear stack of three uniaxial accelerometers <NUM> stacked on top of a linear stack of three uniaxial magnetometers <NUM>. Stacking the sensors <NUM>, <NUM> in a linear arrangement results in a relatively large volumetric package or envelope of the sensor system <NUM>. For instance, related art measurement while drilling (MWD) survey tools utilized in the oil and gas industry are typically confined to a <NUM> inch outer diameter chassis <NUM> that fits inside a <NUM> inch drill collar, and the axial arrangement of the sensors <NUM>, <NUM> and corresponding electronics housed in the chassis <NUM> may have a length extending over <NUM> feet along an axis of the chassis <NUM>. Additionally, the relatively large volumetric size of the related art sensor system <NUM> may result in relatively high cost, weight, and power consumption, and may inhibit the sensor system <NUM> from being positioned in an optimal location.

The significant spacing between the sensors <NUM>, <NUM> in the related art sensor system <NUM> may also result in positional errors or uncertainties when the output signal of the sensor system <NUM> is utilized by a navigation algorithm because navigation algorithms typically assume a single point location of the sensor system <NUM>. Although pre-operational calibration may be performed to compensate for the fixed offsets between the sensors <NUM>, <NUM>, the related art sensor system <NUM> is also subject to deformation during use (e.g., during a drilling operation), which may require more complex real-time calibration to compensate for positional errors or uncertainties caused by the deformation of the sensor system <NUM>. Moreover, the related art sensor system <NUM> is also sensitive to external environmental stimuli, such as thermal and mechanical gradients across the sensor system <NUM>, due to the relatively large volumetric size of the sensor system <NUM> and the spacing between the sensors <NUM>, <NUM>. For instance, different thermal or mechanical loads (e.g., stresses) on different portions of the sensor system <NUM> may alter the output of the sensor system <NUM> depending on the distribution of the thermal and mechanical loads across the sensor system <NUM>. These spatially-dependent effects exhibited by the related art sensor system <NUM> may result in positional errors and uncertainties when the sensor system <NUM> is incorporated into a navigation system.

The invention relates to a MEMS sensor suite according to claim <NUM> and a method of manufacturing the MEMS sensor suite according to claim <NUM>. Further embodiments are claimed in the dependent claims. <CIT> relates to a self-contained, integrated micro-cube-sized inertial measurement unit is provided wherein accuracy is achieved through the use of specifically oriented sensors, the orientation serving to substantially cancel noise and other first-order effects, and the use of a noise-reducing algorithm such as wavelet cascade denoising and an error correcting algorithm such as a Kalman filter embedded in a digital signal processor device. <CIT> relates to MEMS devices fabricated using inexpensive substrate materials such as paper or fabric. <CIT> relates to a solid-state heading that comprises a three-axis Hall effect magnetometer and a three-axis accelerometer.

The accelerometer sensor polyhedron may include a flex circuit or a rigid flex printed circuit board. The accelerometer sensor polyhedron may include the rigid flex printed circuit board, and the series of axial accelerometers may be electrically connected together by signal routing wires extending through flexible hinges of the rigid flex printed circuit board.

The magnetometer sensor polyhedron may include a flex circuit or a rigid flex printed circuit board. The magnetometer sensor polyhedron may include the rigid flex printed circuit board, and the series of axial magnetometers may be electrically connected together by signal routing wires extending through flexible hinges of the rigid flex printed circuit board.

The MEMS sensor suite may include a front-end board, and the accelerometer sensor polyhedron and the magnetometer sensor polyhedron may be mounted on the front-end board.

The MEMS sensor suite may include a series of electronic components on the three faces of the accelerometer sensor polyhedron, such as signal amplifiers, filters, and/or analog-to-digital converters.

The MEMS sensor suite may include a series of electronic components on the three faces of the magnetometer sensor polyhedron, such as signal amplifiers, filters, and/or analog-to-digital converters.

The present disclosure is also directed to various methods of manufacturing a MEMS sensor suite. In one embodiment, the method includes connecting a series of sensors to a circuit and folding the circuit into a sensor polyhedron having a series of faces. The series of sensors are on three faces of the series of faces of the sensor polyhedron.

The sensor polyhedron may be a cube and the three faces may be three mutually orthogonal faces.

Folding the circuit into the sensor polyhedron may include positioning the series of sensors connected to the circuit between a folding fixture and a press. The folding fixture defines a cubic cavity and an opening in communication with the cubic cavity. Folding the circuit into the sensor polyhedron may also include moving the press and the folding fixture relatively toward each other and pressing the series of sensors and the circuit into the cubic cavity through the opening in the folding fixture. Pressing the series of sensors and the circuit into the cubic cavity conforms the circuit to a shape of the cubic cavity.

The circuit may be a flex circuit or a rigid flex printed circuit board, and the sensors may include a series of axial accelerometers, a series of axial magnetometers, and/or a series of gyroscopes.

The press may be a solid cube having a size smaller than a size of the cubic cavity in the folding fixture.

The cubic cavity in the folding fixture may have a volume of approximately (about) <NUM> in<NUM>.

The method may also include mounting the sensor cube on a front-end board.

This summary is provided to introduce a selection of features and concepts of embodiments of the present disclosure that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used in limiting the scope of the claimed subject matter. One or more of the described features may be combined with one or more other described features to provide a workable device.

These and other features and advantages of embodiments of the present disclosure will become more apparent by reference to the following detailed description when considered in conjunction with the following drawings. In the drawings, like reference numerals are used throughout the figures to reference like features and components.

The present disclosure is directed to various embodiments of a micro-electro-mechanical (MEMS)-based sensor suite configured to provide an inertial measurement. The MEMS-based sensor suite of the present disclosure may be utilized in measurement while drilling (MWD) survey tools used for underground navigation in the oil and gas industry. The MEMS-based sensor suite of the present disclosure may be utilized in any other suitable environment. For instance, the MEMS-based sensor suite of the present disclosure may be utilized in an autonomous or semi-autonomous vehicle navigation system (e.g., the MEMS-based sensor suite may be utilized in driver assistant systems (SAE Level <NUM>) to fully autonomous vehicles (SAE Level <NUM>)). The MEMS-based sensor suite of the present disclosure may provide dead reckoning for vehicle navigation during GPS blackouts periods (e.g., <NUM> minutes or longer between GPS acquisition) to provide continuous vehicle navigation and/or guidance during the GPS blackout periods. The MEMS-based sensor suite may also be positioned internally in an autonomous or semi-autonomous vehicle to augment or supplant external sensors on the vehicle in environmental conditions where external sensors on the vehicle are impaired (e.g., environmental conditions in which visual cues are difficult for the external sensors to discern). Additionally, the MEMS-based sensor suite of the present disclosure may be utilized to provide navigation in direct impact systems (e.g., small diameter bombs (SMB)) or unmanned aerial vehicles. In one or more embodiments, the MEMS-based sensor suite of the present disclosure may meet the low size, weight, power, and cost (C-SWAP) requirements for compact and power-limited platforms. The MEMS-based sensor suite of the present disclosure may also be utilized to provide navigation and/or guidance in closed systems with minimal or no external references (e.g., GPS or other signals).

The MEMS-based sensor suite of the present disclosure is packaged in a smaller configuration than related art sensor suites. For instance, in one or more embodiments, the MEMS-based sensor suite of the present disclosure may exhibit an approximately <NUM> times reduction in length and an approximately <NUM> times reduction in volume compared to related art sensor suites, which is configured to reduce the cost, weight, and power consumption of the MEMS-based sensor suite compared to related art sensor suites. Reducing the packaging volume of the MEMS-based sensor suite compared to related art sensor suites is also configured to reduce the sensitivity of the MEMS-based sensor suite to external environmental stimuli. For instance, the MEMS-based sensor suite of the present disclosure is configured to reduce spatially-dependent errors, such as errors due to stress and/or temperature gradients across the MEMS-based sensor suite, by minimizing or at least reducing the distance between the sensors in the sensor suite. Additionally, reducing the packaging volume of the MEMS-based sensor suite compared to related art sensor suites is also configured to increase sensor placement accuracy and enable insertion of the MEMS-based sensor suite into optimal locations inaccessible by related art sensor suites.

When the MEMS-based sensor suite of the present disclosure is incorporated into a navigation system that assumes a single point location of the sensor suite, the reduced volumetric size of the MEMS-based sensor suite compared to related art sensor suites is configured to increase the positional accuracy of the navigation system by more closely positioning the sensors of the sensor suite to the single point location. Furthermore, reducing the packaging volume of the MEMS-based sensor suite is configured to reduce deformation of the sensor suite during use (e.g., during a drilling operation) compared to related art sensor suite systems, and this reduction in deformation is configured to increase the accuracy of the output signal of the sensor suite (e.g., increase the accuracy of the location and heading output signal of the sensor suite). The MEMS-based sensor suite of the present disclosure is also configured to reduce sensor-to-sensor misalignments and non-orthogonalities compared to related art sensor suites, which would otherwise contribute to errors or uncertainties in the location and heading output signals of the sensor suite.

With reference now to <FIG>, a MEMS-based sensor suite <NUM> according to one embodiment of the present disclosure includes a housing or a chassis <NUM> housing a three axis accelerometer <NUM>, a three axis gyroscope <NUM>, and a three axis magnetometer <NUM>. In the illustrated embodiment, the three axis accelerometer <NUM> includes an accelerometer sensor polyhedron (e.g., a cube) <NUM> or die having a series of faces <NUM> and three uniaxial accelerometers <NUM>, <NUM>, <NUM> on three faces <NUM> (e.g., three mutually orthogonal faces) of the accelerometer sensor polyhedron <NUM>. In the illustrated embodiment, the three uniaxial accelerometers <NUM>, <NUM>, <NUM> include a first MEMS accelerometer <NUM> configured to measure a vector component of gravity along an x-axis, a second MEMS accelerometer <NUM> configured to measure a vector component of gravity along a y-axis orthogonal to the x-axis, and a third MEMS accelerometer <NUM> configured to measure a vector component of gravity along a z-axis orthogonal to both the x-axis and the y-axis. In the illustrated embodiment, the uniaxial MEMS accelerometers <NUM>, <NUM>, <NUM> are aligned with the x-, y-, and z-axes, respectively, of the accelerometer cube such that the uniaxial MEMS accelerometers <NUM>, <NUM>, <NUM> have mutually orthogonal orientations. Together, the uniaxial MEMS accelerometers <NUM>, <NUM>, <NUM> define a triaxial MEMS accelerometer configured to measure or determine an orientation of the three axis accelerometer <NUM> with respect to the gravitational force of Earth.

With continued reference to the embodiment illustrated in <FIG>, the faces <NUM> of the accelerometer sensor polyhedron <NUM> of the three axis accelerometer <NUM> are defined by circuits <NUM>, <NUM>, <NUM> on which the uniaxial MEMS accelerometers <NUM>, <NUM>, <NUM>, respectively, are mounted. In one or more embodiments, each of the circuits <NUM>, <NUM>, <NUM> may be a flex circuit or a rigid flex printed circuit board. In one or more embodiments, each of the circuits <NUM>, <NUM>, <NUM> of the three axis accelerometer <NUM> may also include signal conditioning circuitry proximate (e.g., directly adjacent) the uniaxial MEMS accelerometers <NUM>, <NUM>, <NUM>, respectively. Additionally, in one or more embodiments, the three axis accelerometer <NUM> may include one or more electronic components on the circuits <NUM>, <NUM>, <NUM> and coupled the uniaxial MEMS accelerometers <NUM>, <NUM>, <NUM> for processing the output signal of the uniaxial MEMS accelerometers <NUM>, <NUM>, <NUM>, such as, for instance, an amplifier, a signal filter, an analog-to-digital converter (ADC), or combinations thereof. In one or more embodiments, the three axis accelerometer <NUM> may include one or more of these electronic components for each of the three uniaxial MEMS accelerometers <NUM>, <NUM>, <NUM>.

Although in one or more embodiments it is referred to herein as a "cube," in one or more embodiments, the accelerometer sensor polyhedron <NUM> may not be a complete cube and one or more faces <NUM> of the accelerometer sensor polyhedron <NUM> may be open. For instance, in one or more embodiments, the accelerometer sensor polyhedron <NUM> may include three closed faces <NUM> corresponding to the uniaxial MEMS accelerometers <NUM>, <NUM>, <NUM> and three open faces.

In one or more embodiments, the accelerometer sensor polyhedron <NUM> occupies a bulk volume or a total volume of approximately <NUM> in<NUM> (e.g., the accelerometer sensor cube <NUM> has a length l of approximately <NUM> in, a width w of approximately <NUM> in, and a height h of approximately <NUM> in). In one or more embodiments, the uniaxial MEMS accelerometers <NUM>, <NUM>, <NUM> have a size (e.g., an area) smaller than the faces <NUM> of the accelerometer polyhedron <NUM>. In one embodiment, each of the faces <NUM> of the accelerometer sensor cube <NUM> has an area of approximately <NUM> in<NUM> and each of the uniaxial MEMS accelerometers <NUM>, <NUM>, <NUM> has an area from approximately <NUM> in<NUM> to approximately <NUM> in<NUM>. In one embodiment, each of the faces <NUM> of the accelerometer sensor polyhedron <NUM> has an area of approximately <NUM> in<NUM> and each of the uniaxial MEMS accelerometers <NUM>, <NUM>, <NUM> has an area of approximately <NUM> in<NUM> (e.g., each of the uniaxial MEMS accelerometers <NUM>, <NUM>, <NUM> has length of approximately <NUM> inch and a width of approximately <NUM> inch).

With continued reference to the embodiment illustrated in <FIG>, the three axis gyroscope <NUM> of the MEMS-based sensor suite <NUM> includes a gyroscope sensor polyhedron (e.g., a cube) or die <NUM> having a series of faces <NUM> and three uniaxial MEMS gyroscopes <NUM>, <NUM>, <NUM> on three face <NUM> (e.g., three mutually orthogonal faces) of the gyroscope sensor polyhedron <NUM>. In the illustrated embodiment, the three uniaxial gyroscopes include a first MEMS gyroscope <NUM> configured to measure a vector component of Earth's rotation along an x-axis, a second MEMS gyroscope <NUM> configured to measure a vector component of Earth's rotation along a y-axis orthogonal to the x-axis, and a third MEMS gyroscope <NUM> configured to measure a vector component of Earth's rotation along a z-axis orthogonal to both the x-axis and the y-axis. In the illustrated embodiment, the uniaxial MEMS gyroscope <NUM>, <NUM>, <NUM> are aligned with the x-, y-, and z-axes, respectively, of the gyroscope sensor polyhedron <NUM>. Together, the uniaxial MEMS gyroscopes <NUM>, <NUM>, <NUM> define a triaxial MEMS gyroscope configured to measure or determine a heading of the MEMS-based sensor suite <NUM> with respect to Earth's rotation (e.g., the triaxial MEMS gyroscope may be configured to perform an inclination measurement).

With continued reference to the embodiment illustrated in <FIG>, the faces <NUM> of the gyroscope sensor polyhedron <NUM> of the three axis gyroscope <NUM> are defined by circuits <NUM>, <NUM>, <NUM> on which the uniaxial MEMS gyroscopes <NUM>, <NUM>, <NUM>, respectively, are mounted. In one or more embodiments, each of the circuits <NUM>, <NUM>, <NUM> may be a flex circuit or a rigid flex printed circuit board. In one or more embodiments, each of the circuits <NUM>, <NUM>, <NUM> of the three axis gyroscope <NUM> may also include signal conditioning circuitry proximate (e.g., directly adjacent) the uniaxial MEMS gyroscopes <NUM>, <NUM>, <NUM>, respectively. Additionally, in one or more embodiments, the three axis gyroscope <NUM> may include one or more electronic components on the circuits <NUM>, <NUM>, <NUM> and coupled the uniaxial MEMS gyroscopes <NUM>, <NUM>, <NUM> for processing the output signal of the uniaxial MEMS gyroscopes <NUM>, <NUM>, <NUM>, such as, for instance, an amplifier, a signal filter, an analog-to-digital converter (ADC), or combinations thereof. In one or more embodiments, the three axis gyroscope <NUM> may include one or more of these electronic components for each of the three uniaxial MEMS gyroscopes <NUM>, <NUM>, <NUM>.

Although in one or more embodiments it is referred to herein as a "cube," in one or more embodiments, the gyroscope sensor polyhedron <NUM> may not be a complete cube and one or more faces <NUM> of the gyroscope sensor cube <NUM> may be open. For instance, in one or more embodiments, the gyroscope sensor polyhedron <NUM> may include three closed faces <NUM> corresponding to the uniaxial MEMS magnetometers <NUM>, <NUM>, <NUM> and three open faces.

In one or more embodiments, the gyroscope sensor polyhedron <NUM> occupies a bulk volume or a total volume of approximately <NUM> in<NUM> (e.g., the gyroscope sensor cube <NUM> has a length l of approximately <NUM> in, a width w of approximately <NUM> in, and a height h of approximately <NUM> in). In one or more embodiments, the gyroscope sensor polyhedron <NUM> has the same or substantially the same size (e.g., volume) as the accelerometer sensor polyhedron <NUM>. In one or more embodiments, the uniaxial MEMS gyroscopes <NUM>, <NUM>, <NUM> have a size (e.g., an area) smaller than the faces <NUM> of the gyroscope sensor polyhedron <NUM>. In one embodiment, each of the faces <NUM> of the gyroscope sensor polyhedron <NUM> has an area of approximately <NUM> in<NUM> and each of the uniaxial MEMS gyroscopes <NUM>, <NUM>, <NUM> has an area from approximately <NUM> in<NUM> to approximately <NUM> in<NUM>. In one embodiment, each of the faces <NUM> of the gyroscope sensor polyhedron <NUM> has an area of approximately <NUM> in<NUM> and each of the uniaxial MEMS gyroscopes <NUM>, <NUM>, <NUM> has an area of approximately <NUM> in<NUM> (e.g., each of the uniaxial MEMS gyroscopes <NUM>, <NUM>, <NUM> has length of approximately <NUM> inch and a width of approximately <NUM> inch).

With continued reference to the embodiment illustrated in <FIG>, the three axis magnetometer <NUM> of the MEMS-based sensor suite <NUM> includes a magnetometer sensor polyhedron (e.g., a cube) or die <NUM> having a series of faces <NUM> and three uniaxial magnetometers <NUM>, <NUM>, <NUM> on three faces <NUM> (e.g., three mutually orthogonal faces) of the magnetometer sensor polyhedron <NUM>. In the illustrated embodiment, the three uniaxial magnetometers include a first MEMS magnetometer <NUM> configured to measure angular velocity about an x-axis (e.g., a roll axis), a second MEMS magnetometer <NUM> configured to measure angular velocity about a y-axis (e.g., a pitch axis) orthogonal to the x-axis, and a third MEMS magnetometer <NUM> configured to measure angular velocity about a z-axis (e.g., a yaw axis) orthogonal to both the x-axis and the y-axis. In the illustrated embodiment, the uniaxial MEMS magnetometers <NUM>, <NUM>, <NUM> are aligned with the x-, y-, and z-axes, respectively, of the magnetometer sensor polyhedron <NUM>. Together, the uniaxial MEMS magnetometers define a triaxial MEMS magnetometer configured to measure or determine magnetic field vector at the MEMS-based sensor suite <NUM> and the triaxial MEMS magnetometer may be configured to perform an azimuthal measurement. In one or more embodiments, the MEMS-based sensor suite may be provided without the magnetometer <NUM>.

With continued reference to the embodiment illustrated in <FIG>, the faces <NUM> of the magnetometer sensor polyhedron <NUM> of the magnetometer <NUM> are defined by circuits <NUM>, <NUM>, <NUM> on which the uniaxial MEMS magnetometers <NUM>, <NUM>, <NUM>, respectively, are mounted. In one or more embodiments, each of the circuits <NUM>, <NUM>, <NUM> may be a flex circuit or a rigid flex printed circuit board. In one or more embodiments, each of the circuits <NUM>, <NUM>, <NUM> of the magnetometer <NUM> may also include signal conditioning circuitry proximate (e.g., directly adjacent) the uniaxial MEMS magnetometers <NUM>, <NUM>, <NUM>, respectively. Additionally, in one or more embodiments, the magnetometer <NUM> may include one or more electronic components on the circuits <NUM>, <NUM>, <NUM> and coupled the uniaxial MEMS magnetometers <NUM>, <NUM>, <NUM> for processing the output signal of the uniaxial MEMS magnetometers <NUM>, <NUM>, <NUM>, such as, for instance, an amplifier, a signal filter, an analog-to-digital converter (ADC), or combinations thereof. In one or more embodiments, the magnetometer <NUM> may include one or more of these electronic components for each of the three uniaxial MEMS magnetometers <NUM>, <NUM>, <NUM>.

Although in one or more embodiments it is referred to herein as a "cube," in one or more embodiments, the magnetometer sensor polyhedron <NUM> may not be a complete cube and one or more faces <NUM> of the magnetometer sensor polyhedron <NUM> may be open. For instance, in one or more embodiments, the magnetometer sensor polyhedron <NUM> may include three closed faces <NUM> corresponding to the uniaxial MEMS magnetometers <NUM>, <NUM>, <NUM> and three open faces.

In one or more embodiments, the magnetometer sensor polyhedron <NUM> occupies a bulk volume or a total volume of approximately <NUM> in<NUM> (e.g., the magnetometer sensor cube <NUM> has a length l of approximately <NUM> in, a width w of approximately <NUM> in, and a height h of approximately <NUM> in). In one or more embodiments, the magnetometer sensor polyhedron <NUM> has the same or substantially the same size (e.g., volume) as the accelerometer sensor polyhedron <NUM> and/or the magnetometer sensor polyhedron <NUM>. In one or more embodiments, the magnetometers <NUM>, <NUM>, <NUM> have a size (e.g., an area) smaller than the faces of the magnetometer sensor polyhedron <NUM>. In one embodiment, each of the faces <NUM> of the magnetometer sensor polyhedron <NUM> has an area of approximately <NUM> in<NUM> and each of the uniaxial MEMS magnetometers <NUM>, <NUM>, <NUM> has an area from approximately <NUM> in<NUM> to approximately <NUM> in<NUM>. In one embodiment, each of the faces <NUM> of the magnetometer sensor polyhedron <NUM> has an area of approximately <NUM> in<NUM> and each of the uniaxial MEMS magnetometers <NUM>, <NUM>, <NUM> has an area of approximately <NUM> in<NUM> (e.g., each of the uniaxial MEMS magnetometers <NUM>, <NUM>, <NUM> has length of approximately <NUM> inch and a width of approximately <NUM> inch).

<FIG> illustrates the uniaxial MEMS gyroscopes <NUM>, <NUM>, <NUM> of the MEMS-based sensor suite <NUM> according to one embodiment of the present disclosure. As illustrated in <FIG>, each uniaxial MEMS gyroscope <NUM>, <NUM>, <NUM> is sealed in an individual ceramic leadless chip carrier (LCC) <NUM>. In <FIG>, the uniaxial MEMS gyroscope <NUM>, <NUM>, <NUM> is shown prior to sealing the uniaxial MEMS gyroscope <NUM>, <NUM>, <NUM> in the LCC <NUM> with a lid (i.e., the lid is omitted to reveal the uniaxial MEMS gyroscope <NUM>, <NUM>, <NUM>). In one or more embodiments, the area of the LCC <NUM> is less than or equal to the area of the faces <NUM> of the gyroscope sensor polyhedron <NUM>. In one embodiment, the LCC <NUM> has an area of approximately <NUM> in<NUM> (e.g., a length l of approximately <NUM> in and a width w of approximately <NUM> in) and a thickness T of approximately <NUM> in. Additionally, in one or more embodiments, each uniaxial MEMS gyroscope <NUM>, <NUM>, <NUM> is sealed under vacuum using encapsulated getters (e.g., less than approximately <NUM> mTorr) to preserve the high quality factors and the sensitivity of the uniaxial MEMS gyroscopes <NUM>, <NUM>, <NUM>.

<FIG> illustrates the uniaxial MEMS accelerometers <NUM>, <NUM>, <NUM> and the uniaxial magnetometers <NUM>, <NUM>, <NUM> of the MEMS-based sensor suite <NUM> according to one embodiment of the present disclosure. As illustrated in <FIG>, each uniaxial MEMS accelerometer <NUM>, <NUM>, <NUM> and each uniaxial magnetometer <NUM>, <NUM>, <NUM> is sealed in an individual ceramic leadless chip carrier (LCC) <NUM>. In <FIG>, the uniaxial MEMS accelerometer <NUM>, <NUM>, <NUM> and the uniaxial magnetometer <NUM>, <NUM>, <NUM> is shown prior to sealing the uniaxial MEMS accelerometer <NUM>, <NUM>, <NUM> and the uniaxial magnetometer <NUM>, <NUM>, <NUM> in the LCC <NUM> with a lid (e.g., the lid is omitted to reveal the uniaxial MEMS accelerometer <NUM>, <NUM>, <NUM> and the uniaxial magnetometer <NUM>, <NUM>, <NUM>). In one or more embodiments, the area of the LCC <NUM> is less than or equal to the area of the faces <NUM> of the accelerometer sensor polyhedron <NUM>. In one or more embodiments, the area of the LCC <NUM> is less than or equal to the area of the faces <NUM> of the magnetometer sensor polyhedron <NUM>. In one embodiment, the LCC <NUM> has an area of approximately <NUM> in<NUM> (e.g., a length l of approximately <NUM> in and a width w of approximately <NUM> in) and a thickness T of approximately <NUM> in. Additionally, in one or more embodiments, each uniaxial MEMS accelerometer <NUM>, <NUM>, <NUM> is hermetically sealed under an inert gas to dampen unwanted oscillations. In one or more embodiments, each uniaxial MEMS magnetometer <NUM>, <NUM>, <NUM> is sealed under vacuum using encapsulated getters (e.g., less than approximately <NUM> mTorr) to preserve the high quality factors and the sensitivity of the uniaxial MEMS magnetometers <NUM>, <NUM>, <NUM>.

With reference now to <FIG>, a system <NUM> for manufacturing a MEMS-based sensor suite <NUM> according to one embodiment of the present disclosure includes a folding fixture <NUM> and a press <NUM>. In the illustrated embodiment, the folding fixture <NUM> defines a cubic cavity <NUM> and the press <NUM> is a solid cubic anvil configured to extend at least partially into the cubic cavity <NUM>. Additionally, in the illustrated embodiment, an outer surface (e.g., a face) of the folding fixture <NUM> defines an opening <NUM> (e.g., a square opening) in communication with the cubic cavity <NUM>. In the illustrated embodiment, the opening <NUM> in the folding fixture <NUM> faces the press <NUM>, and the press <NUM> is aligned with the opening <NUM> in the folding fixture <NUM>. In the illustrated embodiment, the cubic cavity <NUM> in the folding fixture <NUM> has a volume of approximately <NUM> in<NUM> (e.g., a length of approximately <NUM> inch, a width of approximately <NUM> inch, and a depth of approximately <NUM> inch). In the illustrated embodiment, the opening <NUM> in the folding fixture <NUM> has an area of approximately <NUM> in<NUM> (e.g., a length of approximately <NUM> inch and a width of approximately <NUM> inch). Additionally, in the illustrated embodiment, the press <NUM> is slightly smaller than the cubic cavity <NUM> in the folding fixture <NUM> such that the press <NUM> is configured to extend at least partially into the cubic cavity <NUM> in the folding fixture <NUM> (e.g., the cubic cavity <NUM> in the folding fixture <NUM> is configured (sized and shaped) to accommodate the press <NUM>).

To form a MEMS-based sensor suite according to one embodiment of the present disclosure, a series of sensors <NUM>, <NUM>, <NUM> are connected (e.g., soldered) to at least one circuit <NUM>, and the sensors <NUM>, <NUM>, <NUM> connected to the at least one circuit <NUM> are positioned between the folding fixture <NUM> and the press <NUM>. The press <NUM> is then moved (arrow <NUM>) relative toward the folding fixture <NUM> (e.g., the press <NUM> is moved toward the folding fixture <NUM>, the folding fixture <NUM> is moved toward the press <NUM>, or the folding fixture <NUM> and the press <NUM> are both moved toward each other) such that the sensors <NUM>, <NUM>, <NUM> mounted on the at least one circuit <NUM> are pressed into the cubic opening <NUM> in the folding fixture <NUM> by the press <NUM>. As the sensors <NUM>, <NUM>, <NUM> and the circuit <NUM> are pressed into the cubic opening <NUM> in the folding fixture <NUM> by the press <NUM>, the sensors <NUM>, <NUM>, <NUM> and the circuit <NUM> are folded (arrows <NUM>, <NUM>) about x- and y-axes (e.g., axes <NUM>, <NUM> in-plane with the opening <NUM> of the cubic chamber <NUM>) such the sensors <NUM>, <NUM>, <NUM> and the circuit <NUM> conform to sidewalls <NUM> (e.g., three mutually orthogonal sidewalls) of the cubic chamber <NUM> and corresponding sidewalls <NUM> (e.g., three mutually orthogonal sidewalls) of the press <NUM>. In the illustrated embodiment, after the sensors <NUM>, <NUM>, <NUM> and the circuit <NUM> have been pressed into the cubic chamber <NUM> by the press <NUM>, the sensors <NUM>, <NUM>, <NUM> and the circuit <NUM> form a sensor polyhedron (e.g., the accelerometer sensor cube <NUM>, the magnetometer sensor cube <NUM>, or the gyroscope sensor cube <NUM> illustrated in <FIG>) and the sensors <NUM>, <NUM>, <NUM> are positioned on three mutually orthogonal faces of the sensor cube. In one or more embodiments, after the sensors <NUM>, <NUM>, <NUM> and the at least one circuit <NUM> have been folded into the sensor cube, the circuit <NUM> may be coupled to the sidewalls <NUM> of the press <NUM> with an adhesive (e.g., an adhesive may be applied to the sidewalls <NUM> of the press <NUM> and/or a surface of the circuit <NUM> opposite the surface on which the sensors <NUM>, <NUM>, <NUM> are mounted). Accordingly, in one or more embodiments, the press <NUM> may form an interior support structure of the sensor cube. In one or more embodiments, the press <NUM> may be withdrawn from the cubic cavity <NUM> of the folding fixture <NUM> after pressing the sensors <NUM>, <NUM>, <NUM> and the circuit <NUM> into the cubic cavity <NUM> such that the sensor cube is hollow.

The sensors <NUM>, <NUM>, <NUM> may be any suitable type or kind of sensor depending on the type of information and signals the MEMS-based sensor suite is desired to generate or transmit and/or type of system into which the MEMS-based sensor suite is intended to be incorporated (e.g., a navigation system for a wellbore or an autonomous or semi-autonomous vehicle). For instance, in one embodiment, the sensors <NUM>, <NUM>, <NUM> may be uniaxial MEMS accelerometers. In another embodiment, the sensors <NUM>, <NUM>, <NUM> may be uniaxial MEMS magnetometers. In a further embodiment, the sensors <NUM>, <NUM>, <NUM> may be uniaxial MEMS gyroscopes. In one or more embodiments, the sensors <NUM>, <NUM>, <NUM> may be any suitable combination of uniaxial MEMS accelerometers, uniaxial MEMS magnetometers, and uniaxial MEMS gyroscopes. The system <NUM> illustrated in <FIG> may be utilized to manufacture the embodiment of the IMU <NUM>, the compass <NUM>, and the gyroscope <NUM> illustrated in <FIG>.

Additionally, in the illustrated embodiment, the system <NUM> also includes a front-end board <NUM>. The front-end board <NUM> may support one or more electronic components for processing the output signal of the sensors <NUM>, <NUM>, <NUM>, such as, for instance, an amplifier, a signal filter, an analog-to-digital converter (ADC), or combinations thereof. The one or more sensor cubes may be mounted on the front-end board <NUM>.

In one or more embodiments, the at least one circuit <NUM> may be one or more flex circuits or one or more rigid flex printed circuit boards. <FIG> illustrates a pair of rigid flex printed circuit boards <NUM> according to one embodiment of the present disclosure that are suitable for use with the manufacturing system <NUM> depicted in <FIG>.

<FIG> is a flowchart depicting tasks of a method <NUM> of manufacturing a MEMS-based sensor suite according to one embodiment of the present disclosure. In the embodiment illustrated in <FIG>, the method includes a task <NUM> of connecting a series of sensors to a circuit and a task <NUM> of folding the circuit and the sensors into a sensor cube such that the sensors are on three mutually orthogonal faces of the sensor cube. The sensors may be any suitable type or kind of sensor depending on the type of information and signals the MEMS-based sensor suite is desired to generate and/or transmit and/or type of system into which the MEMS-based sensor suite is intended to be incorporated (e.g., a navigation system for a wellbore or an autonomous or semi-autonomous vehicle). For instance, in one embodiment, the sensors may be uniaxial MEMS accelerometers. In another embodiment, the sensors may be uniaxial MEMS magnetometers. In a further embodiment, the sensors may be uniaxial MEMS gyroscopes. In one or more embodiments, the sensors may be any suitable combination of uniaxial MEMS accelerometers, uniaxial MEMS magnetometers, and uniaxial MEMS gyroscopes. The above-described tasks <NUM>, <NUM> of connecting the sensors to the circuit and folding the sensors and the circuit into a sensor cube may be repeated to form each of the different sensors units of the MEMS-based sensor suite (e.g., the above-described tasks may be performed to form an IMU including an accelerometer sensor cube, and then the tasks may be repeated to form a compass including a gyroscope sensor cube, or vice versa).

In one or more embodiments, the task <NUM> of folding the circuit and the sensors into the sensor cube (e.g., the accelerometer sensor cube, the magnetometer sensor cube, or the gyroscope sensor cube) includes a task <NUM> of positioning the sensors connected to the circuit (e.g., the flex circuit or the rigid flex printed circuit board) between a folding fixture defining a cubic cavity and a press configured to extend at least partially into the cubic cavity of the folding fixture. In one or more embodiments, the task <NUM> of folding the circuit into the sensor cube also includes a task <NUM> of moving the press and the folding fixture relatively toward each other and pressing the plurality of sensors and the circuit into the cubic cavity in the folding fixture, which bends and conforms the circuits to a shape of the cubic cavity in the folding fixture and the exterior shape of the press.

Claim 1:
A MEMS sensor suite (<NUM>), comprising:
a three axis accelerometer, comprising:
an accelerometer sensor polyhedron (<NUM>) comprising a plurality of faces (<NUM>);
a plurality of MEMS axial accelerometers (<NUM>, <NUM>, <NUM>) on three faces of the plurality of faces of the accelerometer sensor polyhedron;
a three axis magnetometer, comprising:
a magnetometer sensor polyhedron (<NUM>) comprising a plurality of faces (<NUM>); and
a plurality of axial magnetometers (<NUM>, <NUM>, <NUM>) on three faces of the plurality of faces of the magnetometer sensor polyhedron
wherein each axial magnetometer (<NUM>, <NUM>, <NUM>) is sealed under vacuum using encapsulated getters to preserve a high quality factor; and
a three axis gyroscope, comprising:
a gyroscope sensor polyhedron (<NUM>) comprising a plurality of faces (<NUM>); and
a plurality of axial gyroscopes (<NUM>, <NUM>, <NUM>) on three faces of the plurality of faces of the gyroscope sensor polyhedron,
wherein each gyroscope (<NUM>, <NUM>, <NUM>) is sealed under vacuum using encapsulated getters to preserve a high quality factor. wherein the three axis accelerometer, the three axis gyroscope, and the three axis magnetometer are stacked in a linear stack.