CN115855032A - Integrated displacement monitoring equipment and method integrating GNSS and MEMS deep displacement technology - Google Patents
Integrated displacement monitoring equipment and method integrating GNSS and MEMS deep displacement technology Download PDFInfo
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Abstract
The invention discloses integrated displacement monitoring equipment and a method integrating GNSS and MEMS deep displacement technology, wherein the displacement monitoring equipment comprises a GNSS monitoring device and N sections of array sensors which are buried in soil of a monitoring point and are sequentially connected from top to bottom, and each section of array sensor comprises a rigid rod and an MEMS triaxial accelerometer fixedly arranged at the top of the rigid rod; the GNSS monitoring device comprises a GNSS upright and a GNSS receiving antenna arranged at the top of the GNSS upright, and the bottom of the GNSS upright is connected with the top of the first section of array sensor through a lower piece. According to the invention, the single-section array sensors are formed by fixedly connecting the MEMS triaxial accelerometer with the rigid body rod, a plurality of single-section array sensors are connected in series, the topmost section of array sensor is fixedly connected with the vertical rod of the GNSS monitoring equipment, and the displacement monitoring of the ground and deep layers of the monitoring point is realized through the algorithm model.
Description
Technical Field
The invention relates to the technical field of displacement monitoring, in particular to integrated displacement monitoring equipment and method fusing GNSS and MEMS deep displacement technology.
Background
The GNSS positioning technology is widely applied to displacement monitoring of landslide, ground settlement, ground cracks and other geological disasters at present. The three-dimensional coordinates of the antenna in a specific coordinate system can be accurately acquired by tracking continuous signals of the GNSS satellite. The technology is based on coordinates and distance, reflects the motion of the target by the difference between the new-stage coordinates and the initial coordinates, and can realize the deformation monitoring of centimeter level and even millimeter level. The technology can carry out continuous monitoring and has the advantages of all weather, high precision, full automation and the like. However, in a complex terrain area, satellite signals are easy to block, multipath effect is serious, and accuracy is affected to a certain extent.
A sensor used in the micro-electro-mechanical system (MEMS) deep displacement monitoring technology is an inclinometer, and a core device of the MEMS deep displacement monitoring technology is an MEMS acceleration sensor, so that the gravity acceleration components in different axial directions can be sensed and measured, the angle between the corresponding axis and the gravity direction is calculated, and the displacement of the corresponding measuring unit is calculated through the change of the angle. The principle is shown in the figure. The technology has the advantages of small size, high precision, good stability, strong independence and the like of the MEMS device, and can make up for the disadvantages of the GNSS technology in theory.
In view of the theoretical complementarity between the GNSS monitoring technology and the MEMS deep displacement monitoring technology, some researchers have developed a combined monitoring method using GNSS and deep displacement technology, and achieved certain results. For example: the invention patent of the invention applied by the Guilin electronic technology university 'a deep level displacement monitoring device and method based on the GNSS technology' (patent publication No. CN 111486781A) discloses a deep level displacement monitoring device and method based on the GNSS technology, the device comprises a GNSS antenna, a network bridge equipment box, a GNSS base station, a central control module and an inclination monitoring and sensing system: the inclination monitoring sensing system comprises an inclinometer pipe, wherein the inclinometer pipe is vertically embedded in the soil body, and the top of the inclinometer pipe is provided with a GNSS antenna; an inclination measuring device is arranged in the inclination measuring pipe, an angle measuring sensor used for measuring an included angle between the inclination measuring pipe and the vertical direction is arranged in the inclination measuring device, and the inclination measuring device is connected with the network bridge equipment box through a cable; the GNSS antenna is used for measuring the three-dimensional coordinate of the inclinometer; the network bridge equipment box is arranged at an undisturbed position to receive data transmitted by the GNSS antenna and the inclinometer equipment; the GNSS base station is arranged on a monitoring pier outside the construction area; the central control module receives data transmitted by the GNSS base station and the bridge equipment box respectively, calculates the inclination values of the stratums at different depths according to the current elevation and the plane position of the top of the inclinometer pipe and the change values and the change amplitudes of the elevation and the plane position, and realizes deformation monitoring of different underground depths.
Currently, no matter the GNSS and the deep inclinometer work independently for monitoring, or the above-mentioned GNSS technology-based deep layer displacement monitoring method in the prior art, a key problem is not solved: the GNSS is used as a ground surface displacement monitoring technology, if millimeter-level monitoring precision is achieved, long-time synchronous observation is needed to calculate a base line, and the monitoring period is different from hours to days; if real-time positioning monitoring is required, the precision standard is inevitably reduced to a centimeter level, so that the requirement of monitoring precision in part of actual engineering is met to a millimeter level.
Disclosure of Invention
The invention aims to provide a novel monitoring device integrating GNSS and MEMS deep displacement technology, which improves the precision level of surface displacement by combining the GNSS and a deep inclinometer and does not influence the precision of deep displacement and the real-time performance of monitoring.
In order to achieve the purpose, the invention provides integrated displacement monitoring equipment integrating GNSS and MEMS deep displacement technology, which comprises a GNSS monitoring device and N sections of array sensors connected in sequence, wherein N is an integer greater than or equal to 1, and each section of array sensor comprises a rigid rod and an MEMS triaxial accelerometer fixedly arranged at the top end of the rigid rod; GNSS monitoring devices includes the GNSS pole setting and sets up the GNSS receiving antenna on GNSS pole setting top, the bottom of GNSS pole setting is passed through down the piece and is saved with the top one array sensor's top is connected.
The invention also discloses an integrated displacement monitoring method integrating GNSS and MEMS deep displacement technology, which is characterized in that the integrated displacement monitoring method adopts the equipment to monitor the displacement of a monitoring point, the length of each section of array sensor is L, N sections of array sensors are vertically embedded in soil of the monitoring point, the embedding depth is N multiplied by L, and the two-dimensional coordinate of each section of array sensor in the horizontal plane is (x =0, y = 0); the distance between the bottom surface of the GNSS upright stanchion and the antenna phase center of the GNSS receiving antenna is S; the integrated displacement monitoring method comprises the following steps: when the earth crust changes to cause the displacement of the underground and the earth surface of the monitoring point, the horizontal coordinate change condition of each node position is deduced according to the triaxial angle measured by the MEMS triaxial accelerometer; the specific method for calculating the angle by the MEMS triaxial accelerometer comprises the following steps:
in an initial state, the data measured by the MEMS triaxial accelerometer are normalized to obtain g = (0, 1) T By rotation R N Then, the coordinate after acceleration normalization is obtained as a = (a) x ,a y ,a z ) T And then:
wherein，R N The rotation angle of the MEMS triaxial accelerometer;
from formula 2):
in the above formula, θ is the offset angle of the current position and the initial attitude of the single-section array sensor in the z-axis direction,
the offset angle of the current position and the initial attitude of the single-section array sensor in the y-axis direction is obtained; the three-dimensional direction coordinate offset of the position of the MEMS triaxial accelerometer at the top of the single section array sensor compared with the position of the bottom of the single section array sensor is:
if the bottommost section of array sensor is the first section of array sensor, the horizontal coordinate of the top of the ith section of array sensor at the current stage from bottom to top is as follows:
deducing the horizontal coordinate of the topmost section of the array sensor according to the formula 5), namely the horizontal coordinate of the ground position; because the GNSS upright in the GNSS monitoring device is fixedly connected with the topmost array sensor, the angle offset of the GNSS receiving antenna is consistent with the angle offset of the topmost array sensor; and deducing the three-dimensional plane coordinate variation at the phase center of the GNSS antenna in the same way:
further, the GNSS positioning method is as follows: setting a GNSS reference station to perform carrier phase differential positioning or real-time precise single-point positioning.
Further, if a GNSS reference station is set up for carrier phase differential positioning, the axial direction of the xyz coordinate of the array sensor is kept consistent with the axial direction of the ENU coordinate of the monitoring point when the equipment is erected.
Further, the initial value of the GNSS differential positioning result is set as (E) 0 ,N 0 ,U 0 ) If the positioning result in this period is (E, N, U), the three-dimensional direction coordinate variation value is:
GNSS differential positioning based three-dimensional direction coordinate change result (delta E, delta N, delta U) and MEMS triaxial accelerometer derivation result (delta x) GNSS ,Δy GNSS ,Δz GNSS ) And processing in a weighting mode to obtain a filtering algorithm as shown in a formula 8):
in formula 8), σ 0 The error in the unit weight is determined according to an empirical value or an actual application environment; sigma GNSS-E ,σ GNSS-N ,σ GNSS-U Respectively determining the errors of the GNSS differential positioning result in the east direction, the north direction and the sky direction by a positioning algorithm; sigma MEMS-x ,σ MEMS-y ,σ MEMS-z The mean errors of the GNSS antenna phase center coordinate offset values derived through the MEMS triaxial accelerometer and corresponding to the three-dimensional directions are respectively obtained through the formula 6) according to an error propagation law.
Compared with the prior art, the invention has the following beneficial effects:
(1) The integrated displacement monitoring equipment forms the single-section array sensor by fixedly connecting the MEMS triaxial accelerometer with the rigid body rod, simultaneously connects a plurality of single-section array sensors in series, and fixedly connects the topmost section of array sensor with the vertical rod of the GNSS monitoring equipment, thereby realizing the hardware condition of the integrated displacement monitoring equipment and realizing the displacement monitoring of the ground and the deep layer of the monitoring point.
(2) The integrated displacement monitoring method provided by the invention realizes the one-by-one calculation of the offset angles of the single-section array sensors by utilizing the characteristic that the MEMS triaxial accelerometer senses the direction of the gravity acceleration, and simultaneously calculates the three-dimensional coordinate change value of the top of each section of array sensor by utilizing the mathematical relationship between the length of the rigid body rod and the offset angle, and finally calculates the coordinate change condition of the phase center position of the GNSS antenna. Meanwhile, the deviation condition of the phase center of the GNSS antenna is obtained through a precise single-point positioning algorithm or a carrier differential positioning algorithm, the GNSS positioning result is subjected to constraint on a mathematical model by utilizing an MEMS calculation result, more stable and precise monitoring on earth surface displacement is realized, and meanwhile, the monitoring accuracy of each underground node is ensured.
In addition to the objects, features and advantages described above, other objects, features and advantages of the present invention are also provided. The present invention will be described in further detail below with reference to the drawings.
Drawings
The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the embodiments of the invention without limiting the embodiments of the invention. In the drawings:
FIG. 1 is a schematic diagram of gravitational field angular offset estimation of a MEMS triaxial acceleration sensor;
FIG. 2 is a schematic diagram of an angular derivative deformation of a MEMS triaxial acceleration sensor;
FIG. 3 is a schematic diagram of the operation of the integrated displacement monitoring device of the preferred embodiment of the present invention;
FIG. 4 is a schematic diagram of the operation of a single segment array sensor of the present invention;
wherein, the 1-GNSS monitoring device; 2-array sensor.
Detailed Description
Embodiments of the invention will be described in detail below with reference to the drawings, but the invention can be implemented in many different ways, which are defined and covered by the claims.
Referring to fig. 3, the embodiment provides an integrated displacement monitoring device integrating GNSS and MEMS deep displacement technology, including a GNSS monitoring apparatus 1 and N array sensors 2 sequentially connected from top to bottom, where N is an integer greater than or equal to 1, and each array sensor 2 includes a rigid rod and a MEMS triaxial accelerometer fixedly disposed at the top end of the rigid rod; GNSS monitoring devices 1 includes the GNSS pole setting and sets up the GNSS receiving antenna on GNSS pole setting top, and the bottom of GNSS pole setting is connected with the top of first section array sensor 2 through pushing down the piece. In the structure, the GNSS receiving antenna can be externally connected with a GNSS receiver or directly select a GNSS receiver-antenna integrated machine.
The invention also provides an integrated displacement monitoring method fusing the GNSS and MEMS deep displacement technology, and displacement monitoring of the monitoring point is realized by adopting the integrated displacement monitoring equipment. For N sections of array sensors, the length of a single section of array sensor 2 is set to be L, and the distance between the bottom surface of the GNSS upright stanchion and the antenna phase center of the GNSS receiving antenna is set to be S; when the apparatus is mounted, the holding device is in a vertical state, the burial depth is N × L, and the two-dimensional coordinates of each segment of the array sensor 2 in the horizontal plane are set to (x =0, y = 0). Since the burial depth is generally deep, the bottom position of the device is in a stable state by default. Therefore, the integrated displacement monitoring method comprises the following steps: when the earth crust changes to cause the displacement of the underground and earth surface of the monitoring point, the horizontal coordinate change condition of each node position of the device can be deduced according to the triaxial angle measured by the MEMS triaxial accelerometer. The specific method for calculating the angle by the MEMS triaxial accelerometer comprises the following steps:
when the MEMS triaxial accelerometer is fixed on the rigid rod, and the X axis, the Y axis and the Z axis of the accelerometer are respectively superposed with the E axis, the N axis and the U axis of the monitoring point, the acceleration measured by the MEMS triaxial accelerometer can be considered to represent the gravity acceleration g under the condition that the machine body does not move violently. In the initial state, the data measured by the MEMS triaxial accelerometer are normalized to obtain g = (0, 1) T MEMS triaxial accelerometer rotates by R N After the angle, the coordinate after acceleration normalization is obtained as a = (a) x ,a y ,a z ) T And then:
from formula 2):
taking a single-section array sensor as an example, referring to fig. 4, θ is a deviation angle between the current position and the initial attitude of the single-section array sensor in the z-axis direction,
the offset angle of the current position of the single-section array sensor and the initial attitude in the y-axis direction is shown. The three-dimensional direction coordinate offset of the position of the MEMS triaxial accelerometer at the top of the single section array sensor compared with the position of the bottom of the single section array sensor is:
if the bottommost section of array sensor is the first section of array sensor, the horizontal coordinate of the top of the ith section of array sensor at the current stage from bottom to top is as follows:
and (5) deducing the coordinates of the topmost array sensor, namely the horizontal coordinates of the ground position. Because the GNSS upright in the GNSS monitoring apparatus 1 is fixedly connected to the array sensor located at the topmost part, the angular offset of the GNSS receiving antenna is consistent with the angular offset of the array sensor located at the topmost part; in the same way, the three-dimensional plane coordinate variation at the phase center of the GNSS antenna can be deduced:
in an embodiment of the present invention, the GNSS positioning method is to set a GNSS reference station to perform carrier phase differential positioning (corresponding to the coordinate result is ENU) or to perform real-time precise point positioning (corresponding to the coordinate result is BLH). Taking the setting of a GNSS reference station for carrier phase differential positioning as an example, it is only necessary to keep the xyz coordinate axis of the array sensor and the ENU coordinate axis of the monitoring point to be the same when the integrated displacement monitoring device is erected, and it is ensured that the GNSS positioning result offset direction and the MEMS deep displacement meter calculation result direction are the same, so that no additional coordinate conversion is required.
In an embodiment of the present invention, the initial value of the GNSS differential positioning result is set as (E) 0 ,N 0 ,U 0 ) If the positioning result in this period is (E, N, U), the three-dimensional direction coordinate variation value is:
based on GNSS differential positioning results (Delta E, delta N, delta U) and MEMS triaxial accelerometer derivation results (Delta x) GNSS ,Δy GNSS ,Δz GNSS ) The filtering algorithm can be obtained by processing in a weighting manner as shown in formula 8):
in formula 8), σ 0 The error in unit weight can be determined according to an empirical value or an actual application environment; sigma GNSS-E ,σ GNSS-N ,σ GNSS-U Respectively determining the errors of the GNSS differential positioning result in the east direction, the north direction and the sky direction by a positioning algorithm; sigma MEMS-x ,σ MEMS-y ,σ MEMS-z The mean errors of the GNSS antenna phase center coordinate offset values derived through the MEMS triaxial accelerometer and corresponding to the three-dimensional directions are respectively obtained through the formula 6) according to an error propagation law.
The integrated displacement monitoring method is based on the field of deformation monitoring application, integrates the traditional ground and underground independent monitoring mode on sensor hardware and an algorithm model, provides a method for restraining a GNSS positioning result through a monitoring result of an MEMS (micro-electromechanical system) triaxial accelerometer, greatly avoids the situation of low positioning result precision caused by the influence of GNSS signal shielding and the like, can better replace the original scheme of underground deep layer displacement monitoring and surface displacement monitoring, and realizes the ground and underground integrated three-dimensional monitoring of a specific point location.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (5)
1. The integrated displacement monitoring equipment fused with the GNSS and MEMS deep displacement technology is characterized by comprising a GNSS monitoring device (1) and N sections of array sensors (2) which are sequentially connected, wherein N is an integer greater than or equal to 1, and each section of array sensor comprises a rigid rod and an MEMS triaxial accelerometer fixedly arranged at the top end of the rigid rod; GNSS monitoring devices (1) include the GNSS pole setting and set up the GNSS receiving antenna on GNSS pole setting top, the bottom of GNSS pole setting is passed through down the piece and is partly with top the top of array sensor is connected.
2. An integrated displacement monitoring method integrating GNSS and MEMS deep displacement technology is characterized in that the device of claim 1 is adopted to monitor the displacement of a monitoring point, the length of each section of array sensor (2) is L, N sections of array sensors are vertically buried in soil of the monitoring point, the buried depth is N multiplied by L, and the two-dimensional coordinate of each section of array sensor in a horizontal plane is (x =0, y = 0); the distance between the bottom surface of the GNSS upright stanchion and the antenna phase center of the GNSS receiving antenna is S; the integrated displacement monitoring method comprises the following steps: when the earth crust changes to cause the displacement of the underground and the earth surface of the monitoring point, the horizontal coordinate change condition of each node position is deduced according to the triaxial angle measured by the MEMS triaxial accelerometer; the specific method for calculating the angle by the MEMS triaxial accelerometer comprises the following steps:
in an initial state, the data measured by the MEMS triaxial accelerometer are normalized to obtain g = (0, 1) T By rotation R N Then, the coordinate after acceleration normalization is obtained as a = (a) x ,a y ,a z ) T And then:
wherein R is N The rotation angle of the MEMS triaxial accelerometer;
from formula 2):
in the above formula, θ is the offset angle of the current position and the initial attitude of the single-section array sensor in the z-axis direction,
the offset angle of the current position and the initial attitude of the single-section array sensor in the y-axis direction is obtained; the three-dimensional direction coordinate offset of the position of the MEMS triaxial accelerometer at the top of the single section array sensor compared with the position of the bottom of the single section array sensor is:
if the bottommost section of array sensor is the first section of array sensor, the horizontal coordinate of the top of the ith section of array sensor at the current stage from bottom to top is as follows:
deducing the horizontal coordinate of the topmost section of the array sensor according to the formula 5), namely the horizontal coordinate of the ground position; because the GNSS upright in the GNSS monitoring device (1) is fixedly connected with the array sensor positioned at the topmost part, the angle deviation of the GNSS receiving antenna is consistent with the angle deviation of the array sensor at the topmost part; and deducing the three-dimensional plane coordinate variation at the phase center of the GNSS antenna in the same way:
3. the integrated displacement monitoring method according to claim 2, wherein the GNSS is positioned in a manner that: the GNSS reference station is set for carrier phase differential positioning or real-time precise single-point positioning.
4. The integrated displacement monitoring method according to claim 3, wherein if a GNSS reference station is set up for carrier phase differential positioning, the xyz coordinate axis of the array sensor is kept consistent with the ENU coordinate axis of the monitoring point during erection of the device.
5. The integrated displacement monitoring method according to claim 4, wherein the initial value of the GNSS differential positioning result is set as (E) 0 ,N 0 ,U 0 ) If the positioning result in this period is (E, N, U), the three-dimensional direction coordinate variation value is:
GNSS differential positioning based three-dimensional direction coordinate change result (delta E, delta N, delta U) and MEMS triaxial accelerometer derivation result (delta x) GNSS ,Δy GNSS ,Δz GNSS ) Processing is carried out in a weighting mode, and the obtained filtering algorithm is as shown in a formula 8):
in formula 8), σ 0 The error in the unit weight is determined according to an empirical value or an actual application environment;
σ GNSS-E ,σ GNSS-N ,σ GNSS-U respectively determining the errors of the GNSS differential positioning result in the east direction, the north direction and the sky direction by a positioning algorithm; sigma MEMS-x ,σ MEMS-y ,σ MEMS-z The mean errors of the GNSS antenna phase center coordinate offset values derived through the MEMS triaxial accelerometer and corresponding to the three-dimensional directions are respectively obtained through the formula 6) according to an error propagation law.
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