CN111256688A - Pre-integration algorithm of inertial navigation system - Google Patents
Pre-integration algorithm of inertial navigation system Download PDFInfo
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- CN111256688A CN111256688A CN201911152293.4A CN201911152293A CN111256688A CN 111256688 A CN111256688 A CN 111256688A CN 201911152293 A CN201911152293 A CN 201911152293A CN 111256688 A CN111256688 A CN 111256688A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C21/00—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00
- G01C21/10—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00 by using measurements of speed or acceleration
- G01C21/12—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00 by using measurements of speed or acceleration executed aboard the object being navigated; Dead reckoning
- G01C21/16—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00 by using measurements of speed or acceleration executed aboard the object being navigated; Dead reckoning by integrating acceleration or speed, i.e. inertial navigation
Abstract
The invention discloses a pre-integration algorithm of an inertial navigation system, which comprises the following steps: step 1: initializing definition; step 2: calculating a pre-integration result; and step 3: calculating an equivalent rotation vector; and 4, step 4: calculating the rotation relation of a machine system between two continuous moments; and 5: the inertial state is resolved, and the pre-integration algorithm of the inertial navigation system can reduce the inertial resolution frequency, reduce the operation time and improve the real-time performance of the algorithm on the premise of not losing inertial data in an underwater integrated navigation method.
Description
Technical Field
The invention belongs to the technical field of inertial navigation, and particularly relates to a pre-integration algorithm of a strapdown inertial navigation system.
Background
In an underwater inertial navigation system, the output frequency of carrier inertial data is high and is about 200 Hz. However, the frequently used acoustic sensor data in underwater integrated navigation is updated at a low frequency, namely, the data is updated once in about 10 s. In the multi-sensor data fusion optimization process, a method for solving the maximum posterior probability of the system is often used for navigation positioning of the carrier, and if a conventional inertia factor is added into the data fusion process at the rate of inertia measurement, the data fusion calculation load is increased, and the real-time performance is deteriorated.
For the problem, the common mode is to acquire effective data once every several beats in the inertial data and to use the extracted data to resolve at a lower frequency. In an environment where long-time navigation is needed underwater, the requirement on navigation accuracy is often high, and therefore a calculation method capable of reducing the calculation complexity in a data fusion algorithm and making full use of inertia measurement data is needed.
Disclosure of Invention
The technical problems solved by the invention are as follows: a pre-integration algorithm of an inertial navigation system is provided, and in an underwater integrated navigation method, the inertia resolving frequency is reduced on the basis of not losing inertia data, so that the real-time performance of the algorithm is improved.
The technical scheme of the invention is as follows:
a pre-integration algorithm for an inertial navigation system, comprising the steps of:
step 1: initializing definition;
step 2: calculating a pre-integration result;
and step 3: calculating an equivalent rotation vector;
and 4, step 4: calculating the rotation relation of a machine system between two continuous moments;
and 5: the inertial state is resolved.
Initialization definition in step 1, specifically, initializing position information of a moving carrierSpeed informationAnd attitude informationWherein:in the formula of △ Px、△Py、△PzX, Y, Z, position change amount in three directions, △ Vx、△Vy、△VzIs X, Y, Z the amount of speed change in three directions,is tiTime ti+1Amount of change in attitude at time, tiIs the initial moment of carrier motion and I is the identity matrix.
The pre-integration calculation result in the step 2 specifically comprises: when there is new measurement data at tj+1Calculating the variation of the updated position when the mobile terminal is added to the system at any timeUpdate rate variationUpdating attitude varianceCompute pre-integral △ xi→j+1Wherein t isj+1=tj+△t,tjIs the motion carrier pre-integration calculation time, △ t is the time interval when new measurement data arrives.
calculating an updated attitude change amountThe calculation formula is as follows:in the formulaIs tjTime tj+1Attitude information of the moment;
the step 3 of calculating the equivalent rotation vector specifically includes: in a speed update period T ═ Tj+1-tjIn the shorter case, the equivalent rotation vector Φ is calculated as:
wherein the content of the first and second substances,in the formula (I), the compound is shown in the specification,is the angular velocity of the navigation system relative to the body,is the angular velocity of the inertial system relative to the machine system,is tiThe attitude matrix of the motion carrier at a moment,is the angular velocity of the navigation system relative to the inertial system.
Step 4, calculating the rotation relationship of the machine system between two consecutive moments, wherein the calculation formula is as follows:
step 5 inertial state solution, including position of navigation systemSpeed of rotationAnd postureThe calculation formula is respectively as follows:
is tiTime tjThe attitude rotation matrix at a time of day,is tiThe location of the time of day navigation system,is tiThe attitude matrix of the time-machine system,is tiThe speed of the moment in time is,is tiThe acceleration of gravity at the location of the moment,is tiThe angular velocity of the moving carrier at that moment.
And ending the pre-integration process, selecting the reference coordinate system as the body coordinate system at the moment when the next pre-integration is started, and initializing the following steps: order toAnd entering the next pre-integration process.
The invention has the beneficial effects that: the pre-integration algorithm of the inertial navigation system can reduce the inertial resolving frequency, reduce the operation time and improve the real-time performance of the algorithm on the premise of not losing inertial data in an underwater integrated navigation method.
Detailed Description
The following further details the examples of the invention:
a pre-integration algorithm for an inertial navigation system, comprising the steps of:
step 1: initializing definition;
step 2: calculating a pre-integration result;
and step 3: calculating an equivalent rotation vector;
and 4, step 4: calculating the rotation relation of a machine system between two continuous moments;
and 5: the inertial state is resolved.
Initialization definition in step 1, specifically, initializing position information of a moving carrierSpeed informationAnd attitude informationWherein:in the formula of △ Px、△Py、△PzX, Y, Z, position change amount in three directions, △ Vx、△Vy、△VzIs X, Y, Z the amount of speed change in three directions,is tiTime ti+1Amount of change in attitude at time, tiIs the initial moment of carrier motion and I is the identity matrix.
The pre-integration calculation result in the step 2 specifically comprises: when there is new measurement data at tj+1Calculating the variation of the updated position when the mobile terminal is added to the system at any timeUpdate rate variationUpdating attitude varianceCompute pre-integral △ xi→j+1Wherein t isj+1=tj+△t,tjIs the moment of the pre-integration calculation of the moving carrier,△tis the time interval in which new metrology data arrives.
calculating an updated attitude change amountThe calculation formula is as follows:in the formulaIs tjTime tj+1Attitude information of the moment;
the step 3 of calculating the equivalent rotation vector specifically includes: in a speed update period T ═ Tj+1-tjIn the shorter case, the equivalent rotation vector Φ is calculated as:
wherein the content of the first and second substances,in the formula (I), the compound is shown in the specification,is the angular velocity of the navigation system relative to the body,is the angular velocity of the inertial system relative to the machine system,is tiThe attitude matrix of the motion carrier at a moment,is the angular velocity of the navigation system relative to the inertial system.
Step 4, calculating the rotation relationship of the machine system between two consecutive moments, wherein the calculation formula is as follows:
step 5 inertial state solution, including position of navigation systemSpeed of rotationAnd postureThe calculation formula is respectively as follows:
is tiTime tjThe attitude rotation matrix at a time of day,is tiThe location of the time of day navigation system,is tiThe attitude matrix of the time-machine system,is tiThe speed of the moment in time is,is tiThe acceleration of gravity at the location of the moment,is tiThe angular velocity of the moving carrier at that moment.
The pre-integration process is finished, and when the next pre-integration is started, the reference coordinate system is selected as the body coordinate system at the moment, and the following initialization is carried out: order toAnd entering the next pre-integration process.
When the pre-integration step length is 50 steps, the error of the equivalent inertia calculation method is larger than that of the traditional binary sample algorithm, although the equivalent inertia calculation finally has larger error in simulation data of about 7 hours, the error of the equivalent algorithm and the traditional algorithm are kept in the same order of magnitude, and the equivalent algorithm is an effective approximation of the traditional algorithm. Meanwhile, the two methods are compared in simulation time, 253.780516s is used in the traditional calculation method, 185.32451s is used in the equivalent calculation method, and therefore the equivalent calculation method is better in calculation efficiency. In the practical application process, the relation between the calculation precision and the calculation time is balanced, and the calculation can be performed by adopting an equivalent inertia calculation method under the conditions that the precision requirement is high, the data volume is large, and the real-time performance of the calculation is seriously influenced.
In the three-dimensional simulation, the pre-integration algorithm times at several different step sizes are compared, as shown in the following table:
as can be seen from the table, in the pre-integration-based inertial solution algorithm, the operation time gradually shortens as the integration step increases. The longer the pre-integration time, the lower the accuracy of the inertial solution algorithm, but the better the real-time performance of the algorithm. Therefore, in practical application, on the premise of ensuring that the pre-integration time is shorter, the step length of the pre-integration is reasonably set to avoid overlarge resolving error.
The above-described embodiments are merely illustrative of one of the preferred embodiments of the present invention and do not limit the spirit and scope of the present invention. Various changes and modifications of the technical solution of the present invention should fall within the protection scope of the present invention without departing from the concept of the present invention, and the technical contents of the present invention are all recorded in the claims.
Claims (8)
1. A pre-integration algorithm for an inertial navigation system, comprising: the method comprises the following steps:
step 1: initializing definition;
step 2: calculating a pre-integration result;
and step 3: calculating an equivalent rotation vector;
and 4, step 4: calculating the rotation relation of a machine system between two continuous moments;
and 5: the inertial state is resolved.
2. The pre-integration algorithm of an inertial navigation system according to claim 1, wherein: initialization definition in step 1, specifically, initializing position information of a moving carrierSpeed informationAnd attitude informationWherein:in the formula,. DELTA.Px、ΔPy、ΔPzX, Y, Z is the position variation in three directions, Δ Vx、ΔVy、ΔVzIs X, Y, Z the amount of speed change in three directions,is tiTime ti+1Amount of change in attitude at time, tiIs the initial moment of carrier motion and I is the identity matrix.
3. The pre-integration algorithm of an inertial navigation system according to claim 1, wherein: the pre-integration calculation result in the step 2 specifically comprises: when there is new measurement data at tj+1Calculating the variation of the updated position when the mobile terminal is added to the system at any timeUpdate rate variationUpdating attitude varianceCalculating a pre-integral Deltaxi→j+1Wherein t isj+1=tj+Δt,tjIs the moment of the pre-integration calculation of the moving carrier, and Δ t is the time interval of the arrival of new measurement data.
4. The pre-integration algorithm for computing an inertial navigation system according to claim 3, wherein: the calculated updated position variation amountThe calculation formula is as follows:
calculating an updated attitude change amountThe calculation formula is as follows:in the formulaIs tjTime tj+1Attitude information of the moment;
5. the pre-integration algorithm of an inertial navigation system according to claim 1, wherein: the step 3 of calculating the equivalent rotation vector specifically includes: in a speed update period T ═ Tj+1-tjIn the shorter case, the equivalent rotation vector Φ is calculated as:
wherein the content of the first and second substances,in the formula (I), the compound is shown in the specification,is the angular velocity of the navigation system relative to the body,is the angular velocity of the inertial system relative to the machine system,is tiThe attitude matrix of the motion carrier at a moment,is the angular velocity of the navigation system relative to the inertial system.
7. the pre-integration algorithm of an inertial navigation system according to claim 1, wherein: step 5 inertial state solution, including position of navigation systemSpeed of rotationAnd postureThe calculation formula is respectively as follows:
is tiTime tjThe attitude rotation matrix at a time of day,is tiThe location of the time of day navigation system,is tiThe attitude matrix of the time-machine system,is tiThe speed of the moment in time is,is tiThe acceleration of gravity at the location of the moment,is tiThe angular velocity of the moving carrier at the moment;
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Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
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CN112146653A (en) * | 2020-08-03 | 2020-12-29 | 河北汉光重工有限责任公司 | Method for improving integrated navigation resolving frequency |
CN112284379A (en) * | 2020-09-17 | 2021-01-29 | 江苏大学 | Inertia pre-integration method of combined motion measurement system based on nonlinear integral compensation |
CN112464432A (en) * | 2020-10-27 | 2021-03-09 | 江苏大学 | Inertial pre-integration optimization method based on double-speed numerical integration structure |
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郭凯祥等: "一种快速的基于预积分的SINS等价解算方法", 《舰船电子对抗》 * |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN112146653A (en) * | 2020-08-03 | 2020-12-29 | 河北汉光重工有限责任公司 | Method for improving integrated navigation resolving frequency |
CN112284379A (en) * | 2020-09-17 | 2021-01-29 | 江苏大学 | Inertia pre-integration method of combined motion measurement system based on nonlinear integral compensation |
WO2022057350A1 (en) * | 2020-09-17 | 2022-03-24 | 江苏大学 | Inertial pre-integration method for combined motion measurement system based on nonlinear integral compensation |
CN112284379B (en) * | 2020-09-17 | 2023-09-22 | 江苏大学 | Inertial pre-integration method of combined motion measurement system based on nonlinear integral compensation |
CN112464432A (en) * | 2020-10-27 | 2021-03-09 | 江苏大学 | Inertial pre-integration optimization method based on double-speed numerical integration structure |
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