CN110672095A - Pedestrian indoor autonomous positioning algorithm based on micro inertial navigation - Google Patents
Pedestrian indoor autonomous positioning algorithm based on micro inertial navigation Download PDFInfo
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Abstract
The invention relates to the technical field of navigation positioning, and discloses a pedestrian indoor autonomous positioning algorithm based on micro inertial navigation, which comprises the following steps: a. step detection; b. calculating the attitude, position and speed by dead reckoning; c. and predicting and updating the system error based on the EKF frame. The problem of divergence of a PDR positioning algorithm is restrained, the MEMS and IMU modules are bound on the feet by utilizing the short static time of the feet when a person walks, the static interval of the feet when the person walks is judged by analyzing IMU data, the speed is returned to zero by utilizing the static interval to serve as a zero-speed measurement value, then an EKF algorithm is adopted, each error of an updating system is corrected by utilizing the zero-speed measurement value, and the divergence of the position of the system is restrained. The self-positioning method is realized under the environment (such as indoor environment) where GNSS is rejected, completely independent of external auxiliary equipment and only dependent on the wearable micro inertial navigation module, and the self-positioning of the pedestrian is realized.
Description
Technical Field
The invention relates to the technical field of navigation and positioning, in particular to a pedestrian indoor autonomous positioning algorithm based on micro inertial navigation.
Background
Along with the development of society, people have increasing demands on material culture and navigation positioning. In outdoor open environments, GNSS systems (global navigation satellite systems, such as GPS) are well established and are widely used in our daily lives; however, in the environments such as urban building groups, mountainous areas, forests, indoor areas, etc., GNSS systems often cannot receive signals, so that positioning becomes very difficult. Taking indoor pedestrian positioning as an example, many application scenes, such as battle, fire fighting, medical treatment, tour guide, shopping, games and the like, have urgent requirements on positioning and navigation, can provide better life experience for people, and is a powerful guarantee for life safety! Therefore, the research on the pedestrian positioning method which can be applied to the indoor has great practical significance and greatly promotes the development of the society.
Disclosure of Invention
The invention mainly provides a pedestrian indoor autonomous positioning algorithm based on micro inertial navigation, which is realized in a GNSS refusal environment, for example: in the indoor environment, do not rely on external auxiliary assembly at all, only rely on wearable little inertial navigation module, realize the problem of pedestrian's autonomic location.
In order to solve the technical problems, the invention adopts the following technical scheme:
a pedestrian indoor autonomous positioning algorithm based on micro inertial navigation comprises the following steps:
a. step detection;
b. calculating the attitude, position and speed by dead reckoning;
c. predicting and updating system errors based on an EKF frame;
2. the pedestrian indoor autonomous positioning algorithm based on micro inertial navigation according to claim 1, characterized in that:
the step a is based on the PDR positioning based on the ZUPT and the ZARU, the PDR positioning is based on the detection of the static moment of the IMU falling to the ground, and the detection of the IMU falling to the ground is judged by adopting three conditions based on an accelerometer and a gyroscope:
1: mode of acceleration
2: variance of acceleration mode over time
3: mode of angular velocity
Performing logical and operation on B1, B2 and B3, wherein B is B1& B2& B3, and if and only if B is 1, determining that the foot is grounded and stationary;
in the step b, because the MEMS has zero offset, the zero offset is removed from the original acceleration and angular velocity before the MEMS is input into the EKF frame:
whereinThe acceleration and the angular velocity of the carrier after zero offset correction at the moment k,is an estimated value in an EKF model;
then, updating a direction cosine matrix, wherein the matrix is another expression form of the attitude and can be directly converted into an attitude Euler angle;
whereinIs the DCM estimated by the carrier to navigation system at time k-1,DCM, I predicted from the carrier to the navigation system at the time k3Is a 3 rd order identity matrix, δ ΩkIs thatΔ t is the IMU sampling time interval;
thus, the speed and position estimated under the navigation system can be obtained:
wherein v (k, k-1) and r (k, k-1) respectively represent the predicted speed and position at the moment k, are not corrected by EKF, and g represents the gravity acceleration, i.e. g is approximately equal to 9.8m/s2;
Then, according to the error of EKF estimation, the speed, position and DCM matrix are corrected:
wherein r (k, k), v (k, k),respectively representing the k time, and correcting the position, the speed and the DCM matrix after the EKF is statically detected according to the previous step; delta rkδ v is an EKF state estimation error; delta thetakIs about the state estimation error delta phikThe antisymmetric matrix of (a):
in the step c, the error state of the EKF frame comprises 15 elements:
here, the δ X (k, k) state is, in turn, represented as δ φk: pitch, roll, yaw angle errors;carrier three-axis angular velocity error; delta rk: a spatial position error; delta vk: a spatial velocity error;the carrier triaxial acceleration error, so the state transition model is:
δX(k,k-1)=ΦkδX(k-1,k-1)+Qk-1(1.15)
wherein the state transition matrix is:
wherein the content of the first and second substances,is acceleration under navigation systemOf an inverse-symmetric matrix, Qk-1Is process noise;
the state covariance prediction model is:
the measurement model is as follows:
Zk=HδX(k,k)+Rk(1.20)
Zkfor the measured values, H is the measurement matrix, RkTo measure noise;
thus, the measurement update at time k can be expressed as:
δX(k,k)=δX(k-1,k-1)+Kk[Zk-HδX(k,k-1)](1.21)
wherein, KkExpressed as kalman gain:
then, updating the state covariance to complete the EKF iteration process;
in practical use, the measured values are the velocity v (k, k-1) and ω (k, k-1) when the foot is down, and the corresponding measured value and observation matrix is:
in order to further improve the precision, in the invention, the error between the altitude information measured by the barometer and the vertical displacement calculated by dead reckoning is utilized, the output course of the magnetometer and the course error calculated by an algorithm are introduced, the ZUPT and the ZARU are jointly used as the measured values, the state is cooperatively constrained, the precision is improved, and the corresponding measured values and the observation matrix are as follows:
wherein Δ yaw ═ δ Φ (3) - ΦMag,Δh=r(3)-Hbarometer。
Further, still include:
acquiring an initial pose:
[1] calculating an initial position and an attitude, setting the initial position to be zero, and calculating the initial attitude by (1.26):
where pitch represents the initial pitch angle, roll represents the initial roll angle, G represents the gravitational acceleration, ax,ayRespectively representing the acceleration output values of the x axis and the y axis of the machine body;
[2]and calculating the course by the magnetometer: first according to [1]The pitch and roll angles are calculated in the step (2), and the magnetometer is output to a data body coordinate system: mB_MAG(mx,my,mz) Is converted into a navigation coordinate system by the formula (1.27) and is marked as MN_MAG(Bx,By,Bz) Then, the heading is calculated according to the formula (1.28), and the tilt compensation is realized:
[3] converting the pitch angle, the roll angle and the yaw angle obtained in the previous step into a DCM matrix as initial values:
wherein p represents pitch, r represents roll, and φ represents φmag_yaw。
Has the advantages that: the problem of divergence of a PDR positioning algorithm is restrained, the MEMS and IMU modules are bound on the feet by utilizing the short static time of the feet when a person walks, the static interval of the feet when the person walks is judged by analyzing IMU data, the speed is returned to zero by utilizing the static interval to serve as a zero-speed measurement value, then an EKF algorithm is adopted, each error of an updating system is corrected by utilizing the zero-speed measurement value, and the divergence of the position of the system is restrained. The self-positioning method is realized under the environment (such as indoor environment) where GNSS is rejected, completely independent of external auxiliary equipment and only dependent on the wearable micro inertial navigation module, and the self-positioning of the pedestrian is realized.
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FIG. 1 is a flow chart of an embodiment positioning algorithm;
FIG. 2 is a diagram illustrating a test result of an indoor simple environment algorithm according to an embodiment;
FIG. 3 is a diagram illustrating the results of an indoor EMI environment algorithm test according to an embodiment;
FIG. 4 is a diagram illustrating the test results of an indoor long-time testing algorithm according to an embodiment;
FIG. 5 is a graph of the test results of an indoor and outdoor combined wide-range long-time test algorithm according to an embodiment;
Detailed Description
The following will further describe in detail a pedestrian indoor autonomous positioning algorithm technical solution based on micro inertial navigation according to an embodiment of the present invention.
It should be noted that the test methods described in the following embodiments, unless otherwise specified, are all conventional methods, and are commercially available; in the description of the present invention, the terms "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are only for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.
The first embodiment is as follows: as shown in fig. 1 and fig. 2, the pedestrian indoor autonomous positioning algorithm based on micro inertial navigation of the present embodiment includes the following steps:
a. step detection;
b. calculating the attitude, position and speed by dead reckoning;
c. predicting and updating system errors based on an EKF frame;
2. the pedestrian indoor autonomous positioning algorithm based on micro inertial navigation according to claim 1, characterized in that:
the step a is based on the PDR positioning based on the ZUPT and the ZARU, the PDR positioning is based on the detection of the static moment of the IMU falling to the ground, and the detection of the IMU falling to the ground is judged by adopting three conditions based on an accelerometer and a gyroscope:
1: mode of acceleration
2: variance of acceleration mode over time
3: mode of angular velocity
Performing logical and operation on B1, B2 and B3, wherein B is B1& B2& B3, and if and only if B is 1, determining that the foot is grounded and stationary;
in the step b, because the MEMS has zero offset, the zero offset is removed from the original acceleration and angular velocity before the MEMS is input into the EKF frame:
whereinThe acceleration and the angular velocity of the carrier after zero offset correction at the moment k,is an estimated value in an EKF model;
then, updating a direction cosine matrix, wherein the matrix is another expression form of the attitude and can be directly converted into an attitude Euler angle;
whereinIs the DCM estimated by the carrier to navigation system at time k-1,DCM, I predicted from the carrier to the navigation system at the time k3Is a 3 rd order identity matrix, δ ΩkIs thatΔ t is the IMU sampling time interval;
thus, the speed and position estimated under the navigation system can be obtained:
wherein v (k, k-1) and r (k, k-1) respectively represent the predicted speed and position at the moment k, are not corrected by EKF, and g represents the gravity acceleration, i.e. g is approximately equal to 9.8m/s2;
Then, according to the error of EKF estimation, the speed, position and DCM matrix are corrected:
wherein r (k, k), v (k, k),respectively representing the k time, and correcting the position, the speed and the DCM matrix after the EKF is statically detected according to the previous step; delta rkδ v is an EKF state estimation error; delta thetakIs about the state estimation error delta phikThe antisymmetric matrix of (a):
in the step c, the error state of the EKF frame comprises 15 elements:
here, the δ X (k, k) state is, in turn, represented as δ φk: pitch, roll, yaw angle errors;carrier three-axis angular velocity error; delta rk: a spatial position error; delta vk: a spatial velocity error;the carrier triaxial acceleration error, so the state transition model is:
δX(k,k-1)=ΦkδX(k-1,k-1)+Qk-1(1.15)
wherein the state transition matrix is:
wherein the content of the first and second substances,is acceleration under navigation systemOf an inverse-symmetric matrix, Qk-1Is process noise;
the state covariance prediction model is:
the measurement model is as follows:
Zk=HδX(k,k)+Rk(1.20)
Zkfor the measured values, H is the measurement matrix, RkTo measure noise;
thus, the measurement update at time k can be expressed as:
δX(k,k)=δX(k-1,k-1)+Kk[Zk-HδX(k,k-1)](1.21)
wherein, KkExpressed as kalman gain:
then, updating the state covariance to complete the EKF iteration process;
in practical use, the measured values are the velocity v (k, k-1) and ω (k, k-1) when the foot is down, and the corresponding measured value and observation matrix is:
in order to further improve the precision, in the invention, the error between the altitude information measured by the barometer and the vertical displacement calculated by dead reckoning is utilized, the output course of the magnetometer and the course error calculated by an algorithm are introduced, the ZUPT and the ZARU are jointly used as the measured values, the state is cooperatively constrained, the precision is improved, and the corresponding measured values and the observation matrix are as follows:
wherein Δ yaw ═ δ Φ (3) - ΦMag,Δh=r(3)-Hbarometer。
Further comprising: acquiring an initial pose:
[1] calculating an initial position and an attitude, setting the initial position to be zero, and calculating the initial attitude by (1.26):
where pitch represents the initial pitch angle, roll represents the initial roll angle, G represents the gravitational acceleration, ax,ayRespectively representing the acceleration output values of the x axis and the y axis of the machine body;
[2]and calculating the course by the magnetometer: first according to [1]The pitch and roll angles are calculated in the step (2), and the magnetometer is output to a data body coordinate system: mB_MAG(mx,my,mz) Is converted into a navigation coordinate system by the formula (1.27) and is marked as MN_MAG(Bx,By,Bz) Then, the heading is calculated according to the formula (1.28), and the tilt compensation is realized:
[3] converting the pitch angle, the roll angle and the yaw angle obtained in the previous step into a DCM matrix as initial values:
wherein p represents pitch, r represents roll, and φ represents φmag_yaw。
Further, the algorithm operates as follows:
[1] IMU data filtering: in order to improve the resolving precision, firstly, preprocessing acceleration and gyroscope original data, wherein the acceleration and gyroscope original data comprise acceleration low-pass filtering and gyroscope band-pass filtering, and an adopted filter is Butterworth second-order filtering;
[2] removing zero offset by combining the acceleration and gyroscope data with the state error estimated by the EKF according to the formula (1.8);
[3]from the gyroscope data and the DCM matrix at the previous time according to (1.9): cDCMUpdate the current time CDCMA matrix;
[4]from the obtained CDCMMatrix, converting the body acceleration into the acceleration under the navigation system by the formula (1.17)
[5]Is composed of [3]Calculated CDCMMatrix and [ 4]]Calculating the estimated speed and position of the obtained navigation acceleration according to the formula (1.11) by using the dead reckoning principle;
[6] calculating a state transition matrix from (1.16);
[8] calculating a process noise matrix according to the time parameters;
[9] calculating a state covariance prediction model according to (1.19);
[10] and judging whether the step is in a zero-speed interval, wherein 1 represents a static interval, and 0 represents a swing interval according to the formulas (1.1) to (1.7), so that the step detection is realized.
If the judgment result is '1' according to the [10], the following operations are executed:
[11] updating the kalman gain according to equation (1.22);
[12] determining a measurement value according to equation (1.25), and measuring a transfer matrix;
[13] and updating the state quantity according to the formula (1.21) on the basis of the formulas (11) and (12);
[14] updating the state covariance matrix according to the formula (1.22) on the basis of the (11) and the (12);
[15] updating the cosine matrix of the position, the speed and the direction according to the formula (1.12) according to the state quantity updated in the step (13);
[16] storing the cosine matrix of the position, the speed and the direction in the step (15) as an initial value of the next moment and a starting point of the dead reckoning of the next moment;
[17] and if the judgment result is '0' according to the step [10], skipping the steps from the step [11] to the step [15], and directly executing the step [16 ].
The algorithm firstly carries out pedestrian 'step detection' according to sensor data of a micro inertial navigation module and in combination with a human kinematics rule, and identifies a 'zero-speed interval' (a static interval) in the moving process of a pedestrian; then, the state output of the static interval is utilized, and the linear velocity and the angular velocity in the interval are artificially determined to be zero and are taken as a zero-velocity measurement value; and finally, an EKF algorithm framework is adopted, the zero-speed measurement value, magnetometer data and barometer data are jointly used as an observed value of an EKF state, errors of position, speed and attitude in the course of dead reckoning are corrected, and the purpose of accurate positioning is achieved.
As shown in fig. 1, wherein the barometer, magnetometer, gyroscope, accelerometer in the box represent the sensors used; the content of the dashed box represents the measurement values under the EKF framework for correcting the systematic errors.
In the following, the actual meanings represented by the various parts in fig. 1 are briefly described:
initial pose: the method comprises the steps of initializing state variables, setting initial positions and calculating initial postures and direction cosine matrixes of carriers.
Attitude and position estimation: after zero offset of the body acceleration is removed, the body acceleration is rotated to a navigation coordinate system through a direction cosine matrix, and linear acceleration is obtained after gravity is removed; then integrating to obtain the speed, and integrating the speed again to obtain the position; because the position and the speed through integration have errors, the system state errors are measured through an EKF frame to correct the position, the speed and the attitude errors. And finally outputting the corrected position, speed and attitude information.
Step detection: mainly tie up the orientation module on the foot, according to gyroscope and acceleration data, judge "stationary region" when pedestrian's foot lands and realize the step and detect. In the "rest interval", 2 results were obtained, i.e., ZUPT (zero velocity interval update, whose measured value is the difference between the output velocity and zero) and ZARU (zero angular velocity interval update, whose measured value is the gyroscope output), as measured values of the EKF frame.
EKF state prediction and update: in attitude and position estimation, velocity and position are obtained by acceleration integration, and direction cosine matrix is obtained by gyroscope integration, thus obtaining a prediction equation of the system, and then according to sensor measurement values, such as barometer height difference, magnetometer calculated angle difference, ZARU and ZUPT. And updating the system state error.
Zero offset correction: and correcting the zero offset error of the accelerometer and the gyroscope by using the acceleration and the angular velocity offset estimated in the EKF system state error, so that the measurement result is more accurate.
In order to verify the accuracy of the algorithm, the test is carried out in a plurality of indoor and outdoor scenes.
The evaluation method comprises the following steps:
first, the error between the Start point (Start mark in fig. 2 to 5) and the End point (End mark in fig. 2 to 5) of the observation positioning (in the actual trajectory of the motion, the Start point of the pedestrian coincides with the End point).
And secondly, testing whether the repeatability of the positioning track is good (in actual walking, more repeated tracks exist, and the contact ratio of the middle positioning position is good or not in the movement process is mainly verified).
In fig. 2, in a simple indoor environment (less magnetic field interference), the accuracy of rectangular motion in a small range is tested, and the rectangular track is repeated 4 times, so that the track coincidence degree is very good, and the starting point and the end point are basically coincident.
In fig. 3, in an indoor complex environment (with large magnetic field interference), the contact ratio when the track moves along the fixed track is tested, in an actual test, the track moves repeatedly 8 times, the contact ratio is also very good, and the starting point and the end point are basically overlapped.
In fig. 4, the accuracy of long-time positioning is tested, the walking distance is greater than 1000 meters, the time is about 25 minutes, and it can be seen that the overlap ratio of the algorithm track is very good, and the error of the starting point and the end point is less than 1 meter.
In fig. 5, the limit test is performed, the pedestrian moves about 4000 meters in combination indoors and outdoors, the test time is about 55 minutes, the moving range is large (a rectangular area with the length of about 180 meters and the width of about 120 meters), and the starting point and the end point are about 7 meters in error from the test result.
From the experimental results of fig. 2 to 5, it can be concluded that the present invention has very high positioning accuracy and very good track contact ratio; under the condition of independent positioning without depending on external equipment, the algorithm has low divergence speed and high robustness. Multiple experiments prove that the algorithm precision is superior to 0.2 percent, exceeds similar positioning schemes on the market and reaches the domestic advanced level.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (3)
1. The pedestrian indoor autonomous positioning algorithm based on micro inertial navigation is characterized in that: the method comprises the following steps:
a. step detection;
b. calculating the attitude, position and speed by dead reckoning;
c. and predicting and updating the system error based on the EKF frame.
2. The pedestrian indoor autonomous positioning algorithm based on micro inertial navigation according to claim 1, characterized in that:
step a, PDR positioning based on ZUPT and ZARU, wherein the PDR positioning is based on detecting the static moment of the I steel landing, and the landing of the IMU is detected based on the judgment of an accelerometer and a gyroscope by adopting three conditions:
1: mode of acceleration
2: variance of acceleration mode over time
3: mode of angular velocity
Performing logical and operation on B1, B2 and B3, wherein B is B1& B2& B3, and if and only if B is 1, determining that the foot is grounded and stationary;
in the step b, because the MEMS has zero offset, the zero offset is removed from the original acceleration and angular velocity before the MEMS is input into the EKF frame:
whereinThe acceleration and the angular velocity of the carrier after zero offset correction at the moment k,is an estimated value in an EKF model;
then, updating a direction cosine matrix, wherein the matrix is another expression form of the attitude and can be directly converted into an attitude Euler angle;
whereinIs the DCM estimated by the carrier to navigation system at time k-1,DCM, I predicted from the carrier to the navigation system at the time k3Is a 3 rd order identity matrix, δ ΩkIs thatΔ t is the IMU sampling time interval;
thus, the speed and position estimated under the navigation system can be obtained:
wherein v (k, k-1) and r (k, k-1) respectively represent the predicted speed and position at the moment k, are not corrected by EKF, and g represents the gravity acceleration, i.e. g is approximately equal to 9.8m/s2;
Then, according to the error of EKF estimation, the speed, position and DCM matrix are corrected:
wherein r (k, k), v (k, k),respectively representing the k time, and correcting the position, the speed and the DCM matrix after the EKF is statically detected according to the previous step; delta rkδ v is an EKF state estimation error; delta thetakIs about the state estimation error delta phikThe antisymmetric matrix of (a):
in the step c, the error state of the EKF frame comprises 15 elements:
here, the δ X (k, k) state is, in turn, represented as δ φk: pitch, roll, yaw angle errors;carrier three-axis angular velocity error; delta rk: a spatial position error; delta vk: a spatial velocity error;the carrier triaxial acceleration error, so the state transition model is:
δX(k,k-1)=ΦkδX(k-1,k-1)+Qk-1(1.15)
wherein the state transition matrix is:
wherein the content of the first and second substances,is acceleration under navigation systemOf an inverse-symmetric matrix, Qk-1Is process noise;
the state covariance prediction model is:
the measurement model is as follows:
Zk=HδX(k,k)+Rk(1.20)
Zkfor the measured values, H is the measurement matrix, RkTo measure noise;
thus, the measurement update at time k can be expressed as:
δX(k,k)=δX(k-1,k-1)+Kk[Zk-HδX(k,k-1)](1.21)
wherein, KkExpressed as kalman gain:
then, updating the state covariance to complete the EKF iteration process;
in practical use, the measured values are the velocity v (k, k-1) and ω (k, k-1) when the foot is down, and the corresponding measured value and observation matrix is:
in order to further improve the precision, in the invention, the error between the altitude information measured by the barometer and the vertical displacement calculated by dead reckoning is utilized, the output course of the magnetometer and the course error calculated by an algorithm are introduced, the ZUPT and the ZARU are jointly used as the measured values, the state is cooperatively constrained, the precision is improved, and the corresponding measured values and the observation matrix are as follows:
wherein Δ yaw ═ δ Φ (3) - ΦMag,Δh=r(3)-Hbarometer。
3. The pedestrian indoor autonomous positioning algorithm based on micro inertial navigation according to claim 2, characterized in that: further comprising:
acquiring an initial pose:
[1] calculating an initial position and an attitude, setting the initial position to be zero, and calculating the initial attitude by (1.26):
where pitch represents the initial pitch angle, roll represents the initial roll angle, G represents the gravitational acceleration, ax,ayRespectively representing the acceleration output values of the x axis and the y axis of the machine body;
[2]and calculating the course by the magnetometer: first according to [1]The pitch and roll angles are calculated in the step (2), and the magnetometer is output to a data body coordinate system: mB_MAG(mx,my,mz) Is converted into a navigation coordinate system by the formula (1.27) and is marked as MN_MAG(Bx,By,Bz) Then, the heading is calculated according to the formula (1.28), and the tilt compensation is realized:
[3] converting the pitch angle, the roll angle and the yaw angle obtained in the previous step into a DCM matrix as initial values:
wherein p represents pitch, r represents roll, and φ represents φmag_yaw。
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