WO2013033755A1 - A method and system of recalibrating an inertial sensor - Google Patents
A method and system of recalibrating an inertial sensor Download PDFInfo
- Publication number
- WO2013033755A1 WO2013033755A1 PCT/AU2012/001009 AU2012001009W WO2013033755A1 WO 2013033755 A1 WO2013033755 A1 WO 2013033755A1 AU 2012001009 W AU2012001009 W AU 2012001009W WO 2013033755 A1 WO2013033755 A1 WO 2013033755A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- chassis
- sensor
- inertial sensor
- bias
- determining
- Prior art date
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C25/00—Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass
- G01C25/005—Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass initial alignment, calibration or starting-up of inertial devices
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P21/00—Testing or calibrating of apparatus or devices covered by the preceding groups
Definitions
- the invention relates to calibration of a sensor. More particularly the invention relates, but is not limited, to in field recalibration of inertial sensors. BACKGROUND TO THE INVENTION
- Inertial sensors are used in many applications to measure movement of objects.
- vehicles such aeroplanes and automated vehicles
- electronic devices such as smart phones
- inertial sensors to determine orientation, movement, and/or other relevant variables.
- Inertial sensors typically include gyroscopes, which measure the rate of change of angle with time, and accelerometers, which measure linear acceleration. Often such sensors are collectively packaged into an inertial measurement unit (IMU).
- IMU inertial measurement unit
- a typical IMU will contain at least a three-axis accelerometer, and often includes one or more gyroscopes. IMUs sometimes also contain a 2 or 3 axis magnetometer for sensing the Earth's magnetic field (although not actually an inertial sensor).
- Inertial sensing is often used to determine an 'attitude' of an object or a vehicle (i.e. the rotation of object or vehicle with respect to a reference frame, usually a theoretical perfectly level ground surface), !n many applications, accurate inertial sensing is critical. For example, in precision agriculture, knowledge of 'attitude' of a vehicle is required to compensate for movements of a Global Navigation Satellite Systems (GNSS) antenna through terrain level changes and undulation.
- GNSS Global Navigation Satellite Systems
- sensor precision is often high enough that an offset induced by the tilting of a GNSS antenna mounted on a vehicle can produce a measurable positioning error (e.g. of at least same order of magnitude as the GNSS system itself).
- tilt angle is sometimes compensated with the use of angular estimates derived from sensor measurements produced by an IMU mounted in the vehicle.
- a method of determining an inertial sensor bias including the steps of: obtaining the orientation of the inertial sensor relative to a chassis; obtaining a first inertial sensor measurement;
- the step of determining the sensor bias includes considering the first and second sensor measurements, determining possible bias values, determining constraints, and determining the sensor bias value from possible bias values within the constraints.
- the determined sensor bias value is the only physically possible bias value determined from the possible bias values and the constraints.
- the step of determining possible bias values includes determining an intersection of two spheres of possible bias values, being a circle of values.
- the possible bias values are determined from a gravity constraint.
- the step of determining possible bias values includes solving a linear algebra problem.
- determining the constraints includes using a sensor orientation rotation that corresponds to the obtained orientation of the sensor relative to the chassis.
- the sensor orientation rotation is a rotation matrix.
- the step of determining constraints includes producing a line constraint that converges at least once with the possible bias values.
- the line constraint is a parametric equation.
- a direction vector of the parametric equation is determined from a nullspace solution.
- a point on the line constraint is also determined.
- the point on the line constraint is determined using a minimum norm solution, even more preferably using a pseudoinverse.
- the step of determining the sensor bias includes determining an intersection between the possible bias values and the line constraint.
- the line constraint may intersect the possible bias values at two points, and the step of determining the sensor bias preferably includes selecting one point which is physically possible.
- the step of selecting one point which is physically possible includes determining which point falls within a predetermined range.
- the predetermined range is determined from a range of values provided by the manufacturer of the sensor.
- the step of determining the sensor bias may include determining two line constraint intersection solutions for each inertial sensor measurement. If only one line constraint intersection solution falls within the predetermined range then preferably that solution is determined to be the inertial sensor bias value. If more than one line constraint intersection solution falls within the predetermined range, then preferably the smaller of the two bias values is selected.
- the first inertial sensor measurement and the second inertial sensor measurement are conducted by an inertial measurement unit (IMU) mounted on the chassis.
- the IMU includes at least a three-axis accelerometer.
- the first inertial sensor measurement and the second inertial sensor measurement consist of a measurement of gravity only.
- the sensors are contained in the chassis, preferably a vehicle chassis, which is either rotated in the same location or is returned to the location of the first inertial sensor measurement after rotating the chassis for the second inertial sensor measurement.
- the method may include measuring the rotation of the chassis between the first inertial sensor measurement and the second inertial sensor measurement. Measurement of the rotation of the chassis between the first inertial sensor measurement and the second inertial sensor measurement may include using a yaw sensor and/or manually measuring the rotation.
- a method of calibrating an inertial sensor including the steps of: determining a sensor bias according to the aforementioned method;
- a method of determining a location of a chassis including the steps of: determining a sensor bias according to the aforementioned method;
- GNSS global navigation satellite system
- a system configured to determine a sensor bias, the system including:
- IMU inertial measurement unit
- a computing resource in communication with the IMU and including a processor and memory;
- memory of the computing resource is programmed to instruct the processor to:
- a system of calibrating an inertial measurement unit including: an IMU having one or more sensors mounted at an orientation relative to a chassis;
- a computing resource in communication with the IMU and including a processor and memory; wherein the IMU:
- the computing resource is an embedded system.
- the computing resource may automatically determine when the chassis with the mounted IMU has been rotated or, alternatively, the computing resource may provide a prompt adapted to receive an input from a user to confirm when said chassis has been rotated.
- the prompt may be graphical on a display and may assist the user in determining rotation of said chassis.
- the IMU preferably includes a three-axis accelerometer.
- the IMU may further include one or more angular rate sensors and/or a 2 or 3 axis magnetometer.
- the system may also include a global navigation satellite system (GNSS) component connected to the processor. Output from the GNSS component may be utilised to assist in determining the sensor bias.
- GNSS component preferably includes a GPS receiver. The sensor bias may be determined according to the aforementioned method.
- Figure 1 is a flow chart illustrating steps of a method according to the invention
- Figure 2 is a flow chart illustrating sub-steps of step 130 of the flow chart in figure 1 ;
- Figure 3 illustrates a graphic example of determining a bias value from possible values within constraints.
- the invention generally relates to determining sensor bias for an inertial sensor, particularly an accelerometer.
- Inertial sensors have a bias that changes with temperature and time.
- Such inertial sensors are used in many applications including vehicles.
- the invention is primarily described with reference to vehicles, and even more particularly with reference to land vehicles, no limitation is meant thereby and the invention could be applied to other embodiments including, for example, in electronic devices such as electronic and electromechanical tools, mobile phones, consoles, game controllers, remote controls, etc.
- Figure 1 illustrates a flow chart that has steps (100 to 130) that outline a method according to an embodiment of the invention.
- a first inertial sensor measurement is obtained (step 100) by collecting and processing data
- the IMU will be part of a navigation system which includes a computing resource, typically including a processor and memory. At a point when the vehicle is stationary the sensor data is received and processed by the system.
- an accelerometer sensor For a stationary vehicle, an accelerometer sensor will measure the following: where is the specific force measurement in the body frame, is the rotation from the navigation (locally level) frame to the sensor frame, is the gravity vector in the navigation frame, b 0 is the
- the accelerometer bias, and ⁇ is a non-fixed perturbation on the measurement.
- the sensor data is typically processed using signal processing to determine an estimate of the specific force at the location.
- the estimate of the specific force includes signal processing to account for other factors such as, for example, removal of engine vibration (if the engine is running) or other disturbances.
- the processed estimate of the specific force results in a first inertial sensor measurement .
- the sensor is then rotated 180° (step 110).
- the system prompts a user to turn a chassis, preferably a vehicle chassis, that the sensor is mounted on around 180° once sufficient data has been collected at the first point.
- a chassis preferably a vehicle chassis
- Some vehicles such as excavators, may be able to turn 180° on the same point.
- other vehicles have to be driven and returned to the same location facing the other way.
- positional equipment such as a GPS, may be able to assist the user in returning to the same location.
- a second inertial sensor measurement is obtained (step 120) by collecting and processing data from the sensor. Like the first inertial sensor measurement the sensor data is processed using signal processing to determine an estimate of the specific force which results in a second inertial sensor measurement .
- Each gravity measurement (equation (7) and equation (8)) form a sphere of possible values for the bias in light of the constraints of gravity. If the sensor is rotated on perfectly flat ground for the two inertial sensor measurements (steps 100 and 1200 then the two spheres will coincide. Otherwise, if the rotation is on uneven ground, as is usually the case, an intersection of the two spheres from the 180° manoeuvre will form a circle of values that fulfil the constraints of gravity.
- Figure 2 illustrates step 130 of figure 1 in more detail. By considering the measurements (step 132 of figure 2) and determining the sphere, from perfectly flat ground, or the circle, from uneven ground, the possible bias values for the sensor are determined (step 134).
- a chassis frame in the preferred embodiment a vehicle frame
- the sensor frame known value, typically determined when the sensors are mounted in the chassis
- the rotation from the navigation frame to the vehicle frame i.e. the attitude of the vehicle
- equation (13) can be rewritten to include :
- equation (15) may be rewritten as:
- Figure 3 illustrates a graphical representation of the circular gravity constraint 10 (i.e. the intersection of two spheres of possible bias values discussed previously) and the line constraint 20 for a zero-noise and a perfect 180° rotation condition.
- the intersection of the gravity constraint 10 and the line constraint 20, being points 40 and 50 need to be determined. Once determined, the intersection 40, 50 that falls within a predetermined range 30, which corresponds to the physically possible bias values determined from the sensor datasheet, is the correct bias value (i.e. intersection 50 in figure 3).
- the line constraint 20 may only be approximately on the same plane. In order to cater for this, the intersection of the line constraint 20 with each sphere of possible values determined from the gravity constraint (as discussed previously) is determined.
- intersection of the line constraint 20 with each sphere can be determined given a sphere in the form of: and a line in the form of:
- intersection points may then be determined as:
- intersection represents the correct bias value. Where more than one intersection falls within the predetermined range of physically possible bias values, the intersection that represents the smaller of the two bias values is selected to be the determined bias value.
- the method and system according to the present invention allows a sensor to be easily calibrated without the need to send the sensor, or equipment containing the sensor, to a third party or back to the manufacturer.
- the invention can easily be carried out in a vehicle by rotating the vehicle 180°. This allows the sensors to be recalibrated at minimal cost and with minimal downtime to an operator. Additionally, the relative ease of recalibration means that the sensors can be recalibrated frequently ensuring that any sensor bias due to age or temperature is kept to a minimum, even due to seasonal changes, and the like, if desired.
- a further advantage of the present invention is that no temperature sensors, or other additional components, are required in order to try to estimate the sensor bias. This reduces costs and complexity of devices utilising the invention compared to those that use bias models, and the like, to estimate the bias. Furthermore, the present invention is typically more accurate than devices that use a bias model as the bias is actually measured and not merely assumed to match the bias model.
- the method and system can be utilised to calibrate an IMU in a vehicle on flat and near flat ground by obtaining only two measurements either side of a simple 180° manoeuvre. Operators of vehicles can therefore easily recalibrate the IMU when desired, such as during temperature changes.
- rotation matrices are used in the determination of the sensor offset in the preferred embodiment, it will be appreciated that other representations of rotations may be utilised including, for example, Euler angles, quaternions, and axis-angles.
- adjectives such as first and second, left and right, top and bottom, and the like may be used solely to distinguish one element or action from another element or action without necessarily requiring or implying any actual such relationship or order.
- reference to an integer or a component or step (or the like) is not to be interpreted as being limited to only one of that integer, component, or step, but rather could be one or more of that integer, component, or step etc.
- the terms 'comprises', 'comprising', 'includes', 'including', or similar terms are intended to mean a non-exclusive inclusion, such that a method, system or apparatus that comprises a list of elements does not include those elements solely, but may well include other elements not listed.
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
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Abstract
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Priority Applications (6)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU2012307069A AU2012307069A1 (en) | 2011-09-08 | 2012-08-29 | A method and system of recalibrating an inertial sensor |
BR112014005130A BR112014005130A2 (en) | 2011-09-08 | 2012-08-29 | method and system for sensor recalibration |
CN201280043450.8A CN103782180A (en) | 2011-09-08 | 2012-08-29 | Method and system of recalibrating an inertial sensor |
EP20120830416 EP2753941A4 (en) | 2011-09-08 | 2012-08-29 | A method and system of recalibrating an inertial sensor |
CA2848102A CA2848102A1 (en) | 2011-09-08 | 2012-08-29 | A method and system of recalibrating an inertial sensor |
MX2014002805A MX2014002805A (en) | 2011-09-08 | 2012-08-29 | A method and system of recalibrating an inertial sensor. |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU2011903660 | 2011-09-08 | ||
AU2011903660A AU2011903660A0 (en) | 2011-09-08 | A method and system of recalibrating a sensor |
Publications (1)
Publication Number | Publication Date |
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WO2013033755A1 true WO2013033755A1 (en) | 2013-03-14 |
Family
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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PCT/AU2012/001009 WO2013033755A1 (en) | 2011-09-08 | 2012-08-29 | A method and system of recalibrating an inertial sensor |
Country Status (8)
Country | Link |
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EP (1) | EP2753941A4 (en) |
CN (1) | CN103782180A (en) |
AR (1) | AR087800A1 (en) |
AU (1) | AU2012307069A1 (en) |
BR (1) | BR112014005130A2 (en) |
CA (1) | CA2848102A1 (en) |
MX (1) | MX2014002805A (en) |
WO (1) | WO2013033755A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102022126969B3 (en) | 2022-10-14 | 2023-12-28 | Deutsches Zentrum für Luft- und Raumfahrt e.V. | Calibrating a rotation rate sensor |
Families Citing this family (8)
Publication number | Priority date | Publication date | Assignee | Title |
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CN106767929B (en) * | 2017-01-19 | 2019-11-05 | 浙江大学 | A method of for correcting inertial sensor coordinate axle offset |
US12004852B2 (en) * | 2017-09-28 | 2024-06-11 | Vital Connect, Inc. | Sensor calibration considering subject-dependent variables and/or body positions |
WO2019183750A1 (en) * | 2018-03-26 | 2019-10-03 | 深圳市锐明技术股份有限公司 | Inertia sensor correction method and apparatus, terminal device and storage medium |
US11009522B2 (en) * | 2018-09-07 | 2021-05-18 | Caterpillar Inc. | Systems and methods for calibrating an acceleration sensor using a payload system |
CN109581523B (en) * | 2018-11-12 | 2020-05-01 | 湖北省地震局 | Method and system for calibrating accelerometer by satellite tracking satellite device |
CN111521196B (en) * | 2020-04-14 | 2022-09-06 | 京东方科技集团股份有限公司 | Sensor correction method and device, virtual reality equipment and storage medium |
WO2022198590A1 (en) * | 2021-03-25 | 2022-09-29 | 华为技术有限公司 | Calibration method and apparatus, intelligent driving system, and vehicle |
CN114947627B (en) * | 2022-08-01 | 2022-11-22 | 深圳市云鼠科技开发有限公司 | Determination method, device, equipment and storage medium for initializing IMU of sweeper |
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US7066004B1 (en) * | 2004-09-02 | 2006-06-27 | Sandia Corporation | Inertial measurement unit using rotatable MEMS sensors |
US20080208501A1 (en) * | 2005-07-15 | 2008-08-28 | Jens Fiedler | Method For Determining and Correcting Incorrect Orientations and Offsets of the Sensors of an Inertial Measurement Unit in a Land Vehicle |
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WO2006026751A1 (en) * | 2004-08-31 | 2006-03-09 | Kelsey-Hayes Company | A method for correction of inertial sensor mounting offsets |
EP1701135A1 (en) * | 2005-03-11 | 2006-09-13 | Delphi Technologies, Inc. | Method of calibrating an acceleration sensor |
WO2008068542A1 (en) * | 2006-12-04 | 2008-06-12 | Nokia Corporation | Auto-calibration method for sensors and auto-calibrating sensor arrangement |
US7835880B2 (en) * | 2007-09-29 | 2010-11-16 | Imu Solutions, Inc. | Methods for improving accuracy of measurement and calibration of accelerometer parameters |
US20110077891A1 (en) * | 2009-09-25 | 2011-03-31 | Sirf Technology Holdings, Inc. | Accelerometer-only calibration method |
CN101788305A (en) * | 2010-03-26 | 2010-07-28 | 中北大学 | Method for rapid field calibration of micro inertial measurement unit |
CN102003968B (en) * | 2010-09-03 | 2012-03-14 | 哈尔滨工程大学 | Single-axle table calibration method for fiber optic gyro strapdown inertial navigation system |
-
2012
- 2012-08-29 CN CN201280043450.8A patent/CN103782180A/en active Pending
- 2012-08-29 BR BR112014005130A patent/BR112014005130A2/en not_active IP Right Cessation
- 2012-08-29 AU AU2012307069A patent/AU2012307069A1/en not_active Abandoned
- 2012-08-29 EP EP20120830416 patent/EP2753941A4/en not_active Withdrawn
- 2012-08-29 CA CA2848102A patent/CA2848102A1/en not_active Abandoned
- 2012-08-29 MX MX2014002805A patent/MX2014002805A/en not_active Application Discontinuation
- 2012-08-29 WO PCT/AU2012/001009 patent/WO2013033755A1/en active Application Filing
- 2012-09-06 AR ARP120103296 patent/AR087800A1/en unknown
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
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US7066004B1 (en) * | 2004-09-02 | 2006-06-27 | Sandia Corporation | Inertial measurement unit using rotatable MEMS sensors |
US20080208501A1 (en) * | 2005-07-15 | 2008-08-28 | Jens Fiedler | Method For Determining and Correcting Incorrect Orientations and Offsets of the Sensors of an Inertial Measurement Unit in a Land Vehicle |
Non-Patent Citations (1)
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Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102022126969B3 (en) | 2022-10-14 | 2023-12-28 | Deutsches Zentrum für Luft- und Raumfahrt e.V. | Calibrating a rotation rate sensor |
Also Published As
Publication number | Publication date |
---|---|
AU2012307069A1 (en) | 2014-03-06 |
EP2753941A4 (en) | 2015-04-29 |
BR112014005130A2 (en) | 2017-04-18 |
CN103782180A (en) | 2014-05-07 |
AR087800A1 (en) | 2014-04-16 |
CA2848102A1 (en) | 2013-03-14 |
EP2753941A1 (en) | 2014-07-16 |
MX2014002805A (en) | 2014-04-10 |
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