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US-12625201-B2 - Controlling motion with magnetometers

US12625201B2US 12625201 B2US12625201 B2US 12625201B2US-12625201-B2

Abstract

In one embodiment, an apparatus includes a first magnetometer that measures a magnetic induction and direction of a magnetic field. The first magnetometer has a first coordinate frame that includes a first x axis, a first y axis, and a first z axis. The apparatus includes a second magnetometer that measures the magnetic induction and direction of the magnetic field. The second magnetometer has a second coordinate frame that includes a second x axis, a second y axis, and a second z axis. Each of one or more of the second x axis, the second y axis, or the second z axis is has a predetermined orientation relative to the first x axis, the first y axis, or the first z axis.

Inventors

  • Alexandre TOUTOV
  • Pavlo Borsuk

Assignees

  • Astra Navigation, Inc.

Dates

Publication Date
20260512
Application Date
20220512

Claims (20)

  1. 1 . An apparatus comprising: a first magnetometer operable to measure a magnetic field, wherein the first magnetometer comprises a first coordinate frame that comprises a first x axis, a first y axis, and a first z axis; a second magnetometer operable to measure the magnetic field, wherein: the second magnetometer comprises a second coordinate frame that comprises a second x axis, a second y axis, and a second z axis; and each of one or more of the second x axis, the second y axis, or the second z axis has a predetermined orientation relative to the first x axis, the first y axis, or the first z axis; a third magnetometer operable to measure the magnetic field, wherein the third magnetometer comprises a third coordinate frame that comprises a third x axis, a third y axis, and a third z axis; and a fourth magnetometer operable to measure the magnetic field, wherein: the fourth magnetometer comprises a fourth coordinate frame that comprises a fourth x axis, a fourth y axis, and a fourth z axis; and each of one or more of the fourth x axis, the fourth y axis, or the fourth z axis has a predetermined orientation relative to the third x axis, the third y axis, or the third z axis.
  2. 2 . The apparatus of claim 1 , wherein each of one or more of the orientations is predetermined by being measured.
  3. 3 . The apparatus of claim 1 , wherein: each of one or more of the second x axis, the second y axis, or the second z axis is approximately 180° or 0° from the first x axis, the first y axis, or the first z axis; and each of one or more of the fourth x axis, the fourth y axis, or the fourth z axis is approximately 180° or 0° from the third x axis, the third y axis, or the third z axis.
  4. 4 . The apparatus of claim 1 , wherein: the second x axis is approximately 180° from the first x axis; the second y axis is approximately 180° from the first y axis; the second z axis is approximately 0° from the first z axis; the fourth x axis is approximately 180° from the third x axis; the fourth y axis is approximately 180° from the third y axis; and the fourth z axis is approximately 0° from the third z axis.
  5. 5 . The apparatus of claim 1 , wherein: the second magnetometer is positioned and oriented relative to the first magnetometer such that each of one or more of the second x axis, the second y axis, or the second z axis is approximately 180° from the first x axis, the first y axis, or the first z axis, respectively; and the fourth magnetometer is positioned and oriented relative to the third magnetometer such that each of one or more of the fourth x axis, the fourth y axis, or the fourth z axis is 180° from the third x axis, the third y axis, or the third z axis, respectively.
  6. 6 . The apparatus of claim 1 , wherein: the second magnetometer is positioned relative to the first magnetometer such that measurement of the magnetic field by the second magnetometer along each of one or more of the second x axis, the second y axis, or the second z axis is approximately equal to measurement of the magnetic field by the first magnetometer along each of one or more of the first x axis, the first y axis, or the first z axis, respectively; and the fourth magnetometer is positioned relative to the third magnetometer such that measurement of the magnetic field by the fourth magnetometer along each of one or more of the fourth x axis, the fourth y axis, or the fourth z axis is approximately equal to measurement of the magnetic field by the third magnetometer along each of one or more of the third x axis, the third y axis, or the third z axis, respectively.
  7. 7 . The apparatus of claim 1 , wherein the first, second, third, and fourth magnetometers are arranged on a plane.
  8. 8 . The apparatus of claim 7 , wherein: the first and second magnetometers are positioned along a first line on the plane; and the third and fourth magnetometers are positioned along a second line on the plane that is approximately perpendicular to the first line.
  9. 9 . The apparatus of claim 8 , further comprising: a fifth magnetometer arranged on the plane and positioned along a third line on the plane and operable to measure the magnetic field, wherein the fifth magnetometer comprises a fifth coordinate frame that comprises a fifth x axis, a fifth y axis, and a fifth z axis; a sixth magnetometer arranged on the plane and positioned along a third line on the plane and operable to measure the magnetic field, wherein: the sixth magnetometer comprises a sixth coordinate frame that comprises a sixth x axis, a sixth y axis, and a sixth z axis; and each of one or more of the sixth x axis, the sixth y axis, or the sixth z axis has a predetermined orientation relative to the fifth x axis, the fifth y axis, or the fifth z axis; a seventh magnetometer arranged on the plane and positioned along a fourth line on the plane and operable to measure the magnetic field, wherein the seventh magnetometer comprises a seventh coordinate frame that comprises a seventh x axis, a seventh y axis, and a seventh z axis; and an eighth magnetometer arranged on the plane and positioned along a fourth line on the plane and operable to measure the magnetic field, wherein: the eighth magnetometer comprises an eighth coordinate frame that comprises an eighth x axis, an eighth y axis, and an eighth z axis; and each of one or more of the eighth x axis, the eighth y axis, or the eighth z axis has a predetermined orientation relative to the seventh x axis, the seventh y axis, or the seventh z axis; wherein: the third line is approximately perpendicular to the fourth line; and there is an approximately 45° angle between first line and the third line.
  10. 10 . The apparatus of claim 1 , wherein: the first magnetometer is arranged on a first facet of a three-dimensional shape; and the third magnetometer is arranged on a second facet of the three-dimensional shape.
  11. 11 . The apparatus of claim 10 , wherein: the second magnetometer is arranged on the first facet of the three-dimensional shape; and the fourth magnetometer is arranged on the third facet of the three-dimensional shape.
  12. 12 . The apparatus of claim 10 , wherein: the second magnetometer is arranged on a third facet of the three-dimensional shape; and the fourth magnetometer is arranged on a fourth facet of the three-dimensional shape.
  13. 13 . The apparatus of claim 1 , further comprising a device that is operable to navigate or localize using the first, second, third, and fourth magnetometers.
  14. 14 . The apparatus of claim 1 , further comprising a device that is operable to generate one or more portions of a magnetic map of an area using the first, second, third, and fourth magnetometers.
  15. 15 . A method comprising: receiving output from a sensor set comprising: a first magnetometer operable to measure a magnetic field, wherein the first magnetometer comprises a first coordinate frame that comprises a first x axis, a first y axis, and a first z axis; a second magnetometer operable to measure the magnetic field, wherein: the second magnetometer comprises a second coordinate frame that comprises a second x axis, a second y axis, and a second z axis; and each of one or more of the second x axis, the second y axis, or the second z axis has a predetermined orientation relative to the first x axis, the first y axis, or the first z axis; a third magnetometer operable to measure the magnetic field, wherein the third magnetometer comprises a third coordinate frame that comprises a third x axis, a third y axis, and a third z axis; and a fourth magnetometer operable to measure the magnetic field, wherein: the fourth magnetometer comprises a fourth coordinate frame that comprises a fourth x axis, a fourth y axis, and a fourth z axis; and each of one or more of the fourth x axis, the fourth y axis, or the fourth z axis has a predetermined orientation relative to the third x axis, the third y axis, or the third z axis; and navigating or determining a position of a device based at least in part on the output of the sensor set.
  16. 16 . The method of claim 15 , wherein each of one or more of the orientations is predetermined by being measured.
  17. 17 . The method of claim 15 , wherein: each of one or more of the second x axis, the second y axis, or the second z axis is approximately 180° or 0° from the first x axis, the first y axis, or the first z axis; and each of one or more of the fourth x axis, the fourth y axis, or the fourth z axis is approximately 180° or 0° from the third x axis, the third y axis, or the third z axis.
  18. 18 . The method of claim 15 , wherein: the second x axis is approximately 180° from the first x axis; the second y axis is approximately 180° from the first y axis; the second z axis is approximately 0° from the first z axis; the fourth x axis is approximately 180° from the third x axis; the fourth y axis is approximately 180° from the third y axis; and the fourth z axis is approximately 0° from the third z axis.
  19. 19 . The method of claim 15 , wherein the first, second, third, and fourth magnetometers are arranged on a plane.
  20. 20 . The method of claim 15 , wherein the first magnetometer is arranged on a first facet of a three-dimensional shape; and the third magnetometer is arranged on a second facet of the three-dimensional shape.

Description

TECHNICAL FIELD This disclosure generally relates to magnetic navigation and localization. BACKGROUND Gyroscopic systems (including heading-vertical gyroscope platforms) may be used to determine a vehicle's orientation angles (e.g. heading, pitch, and roll) in a joint rectangular coordinate frame relative to the Earth-Centered, Earth-Fixed (ECEF) coordinate frame, and those calculations may be used to control the vehicle. However, such systems are typically complex, often relying on suites of multiple different sources. Such systems are often relatively heavy (e.g. approximately 5 kg or more) and relatively expensive. As a result, the use of such systems on smaller unmanned or manned aerial vehicles (e.g. up to approximately 100 kg of takeoff weight) and other robots is often impractical. In addition or as an alternative to gyroscopic systems, data from satellite navigation systems may be use to determine a vehicle's course. Many such systems operate on the premise of a Global Navigation Satellite System (GNSS). GNSS is a general term used to describe a network of satellites that can be used to produce position, navigation, and time (PNT) data sets. The Global Positioning System (GPS) is a widely used form of GNSS. Regional applications of such systems are also used to generate more regionally specific PNT data. For example, Galileo can be used in Europe; GLONASS can be used in Russia; and the BeiDou Navigation Satellite System (BDS) can be used in China. GNSSs can have failure points. For example, some GNSSs lose reliability when operated inside buildings or in areas where network communication to the device is intermittent. Some GNSSs lose reliability when operated in dense city environments where large buildings interfere with communication signals. Some GNSSs lose reliability when operated in areas such as caves, tunnels, and mountains that impede location devices' reception of signals from GNSS satellites. Moreover, some GNSSs are susceptible to malicious attacks by electronic interference or physical intervention that degrade their reliability. BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A-1D illustrate example unmanned aerial vehicles (UAVs). FIGS. 2A-2K illustrate example unmanned ground vehicles (UGVs). FIGS. 3A-3D illustrate example unmanned underwater vehicles (UUVs). FIGS. 4A-4G illustrate example unmanned surface vessels (USVs). FIG. 5 illustrates example measurement of an example magnetic field at an example point in space. FIG. 6 illustrates an example magnetometer. FIGS. 7A-7B illustrate an example module with an example magnetometer. FIG. 8 illustrates an example sensor set including four example magnetometers. FIG. 9 illustrates an example sensor set including eight example magnetometers. FIG. 10 illustrates an example sensor set including magnetometers for measuring a distance traversed or speed. FIG. 11 illustrates example magnetic measurements by an example pair of magnetometers. FIG. 12 illustrates an example system for controlling motion with magnetometers. FIG. 13 illustrates an example method for controlling motion with magnetometers. FIG. 14 illustrates an example method for measuring a distance traversed or a speed. FIG. 15 illustrates an example computer system. DESCRIPTION OF EXAMPLE EMBODIMENTS Particular embodiments facilitate autonomous motion of a robot (which may include a UAV, UGV, UUV, or USV) along a route recorded on a data-storage device. In particular embodiments, one or more magnetic fields are recorded along the route and the robot then navigates that route based at least in part on data received from magnetometers or other sensors on the robot. In particular embodiments, recorded magnetic data along a route may be used for information support of navigation and motion-control systems of autonomous robotic systems. In particular embodiments, a robot autonomously or semi-autonomously navigates a route using a magnetic map of the route or an environment of the route. In particular embodiments, a person navigates a route using a magnetic map of the route or an environment of the route. Particular embodiments substantially obviate accelerometers and gyroscopic devices on board the robot. FIGS. 1A-1D illustrate example UAVs. FIG. 1A illustrates an example MAVIC 3 camera drone made by SZ DJI TECHNOLOGY. FIG. 1B illustrates an example U.S. Air Force MQ-1 Predator drone. FIG. 1C illustrates an example KARGU rotary-wing attack drone made by STM SAVUNMA TEKNOLOJILERI MÜHENDISLIK VE TICARET. FIG. 1D illustrates an example ALPAGU fixed-wing attack drone, also made by STM SAVUNMA TEKNOLOJILERI MÜHENDISLIK VE TICARET. Although particular UAVs are described and illustrated herein, this disclosure contemplates any suitable UAVs. In particular embodiments, a UAV is an aircraft without a human pilot, crew, or passengers on board. A UAV may be a component of an unmanned aircraft system (UAS), which may include a ground-based or other controller and a system of communication with the UAV.