Integrated fusion navigation system based on MEMS and fiber-optic gyroscope

Abstract

The invention discloses an integrated fusion navigation system based on an MEMS (Micro Electro Mechanical System) and an optical fiber gyroscope. The integrated fusion navigation system comprises a triaxial optical fiber gyroscope, a triaxial accelerometer, a triaxial MEMS gyroscope, a triaxial MEMS accelerometer, a GNSS (Global Navigation Satellite System) satellite navigation module, a first navigation module and a second navigation module, the data output ends of the three-axis fiber-optic gyroscope and the three-axis accelerometer are connected with the first navigation module, the data output ends of the three-axis MEMS gyroscope and the three-axis MEMS accelerometer are connected with the second navigation module, and the data output end of the GNSS satellite navigation module is connected with the first navigation module and the second navigation module at the same time. The first navigation module and the second navigation module are mutually connected; and the first navigation module and the second navigation module are connected to calculate the received data respectively and then output navigation data respectively. According to the invention, the problem that accurate navigation cannot be realized when a single sensitive element breaks down can be solved.

Description

Technical Field

[0001] The present invention relates to the field of navigation technology, and in particular to an integrated fusion navigation system based on MEMS and fiber optic gyroscope. Background Art

[0002] Inertial navigation systems are generally divided into optical (such as optical fiber, laser, etc.), micromechanical (MEMS), flexible, etc. according to the gyroscope.

[0003] Fiber optic gyroscopes use solid structures and use light as sensitive signals, so the warm-up time is very short, and they are highly reliable, long-lived, and anti-interference. Since the light source is located outside the working circuit, even if it rotates at a low speed, there will be no locking problem similar to that of a laser gyroscope. However, there are still a series of technical problems with fiber optic gyroscopes, which affect the accuracy and stability of fiber optic gyroscopes, such as the effects of temperature transients, vibrations, and polarization. MEMS gyroscopes have outstanding features such as small size, light weight, low cost, low power consumption, good reliability, and a large measurement range. They have broad application prospects, but they are still low-precision gyroscopes with large random drift errors.

[0004] Most of the current navigation systems use one of them as a sensitive element to detect angular rate and acceleration, resulting in the defect of low accuracy; there are also solutions that use a combination of two to complement each other to improve the accuracy of the entire navigation system, but in the actual working process, once one of them fails, it will cause serious and huge problems in the entire navigation system, and navigation will not be possible, which has a very limited improvement in system reliability. Traditionally, redundant backup is achieved in the form of main inertial navigation plus backup inertial navigation. In this mode, the main inertial navigation and backup inertial navigation cannot realize data fusion processing. Any failure of any one-axis gyroscope (a total of 3 axes) or accelerometer (a total of 3 axes) in any inertial navigation will cause the inertial navigation system to fail, thus putting the carrier at great risk; and the two sets of inertial navigation are costly, large in size, and heavy in weight, which seriously restricts the low cost, light and miniaturization of eVolt, drones, etc., and is not conducive to the explosive growth of the industry.

[0005] Therefore, there is an urgent need to provide a navigation system that can fully integrate navigation data and has low cost and small size. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide an integrated fusion navigation system based on MEMS and fiber optic gyroscope, which can solve the problem that accurate navigation cannot be achieved when a single sensitive element fails.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: an integrated fusion navigation system based on MEMS and fiber optic gyroscope, characterized in that it includes a three-axis fiber optic gyroscope, a three-axis accelerometer, a three-axis MEMS gyroscope, a three-axis MEMS accelerometer, a GNSS satellite navigation module, and a first navigation module and a second navigation module; wherein the data output ends of the three-axis fiber optic gyroscope and the three-axis accelerometer are connected to the first navigation module, the data output ends of the three-axis MEMS gyroscope and the three-axis MEMS accelerometer are connected to the second navigation module, the data output end of the GNSS satellite navigation module is connected to the first navigation module and the second navigation module at the same time, and the first navigation module and the second navigation module are connected to each other; the first navigation module and the second navigation module are connected to each other to respectively solve the received data and then output the navigation data for use by the host computer such as the flight control system, and the host computer selects one of them to use according to the navigation system status bit and its own task.

[0008] Furthermore, the three-axis fiber optic gyroscope includes an IMU bracket, and the three-axis sensitive elements of the three-axis fiber optic gyroscope are respectively installed on the sides corresponding to X, Y, and Z of the IMU bracket; the three-axis accelerometer, three-axis MEMS gyroscope, and three-axis MEMS accelerometer are all installed in the IMU bracket, and the GNSS satellite navigation module is installed on the IMU bracket or the shell.

[0009] Furthermore, the working process of the first navigation module includes the following steps: 1) After powering on, it is initialized and then the data of the three-axis fiber optic gyroscope Gf and the three-axis accelerometer Am1 are collected; 2) Receive data from the second navigation module to obtain Gm data of the MEMS gyroscope and Am2 data of the MEMS accelerometer; 3) Receive data from the GNSS satellite guidance module; 4) Determine whether the Gf data is valid, if so, proceed to step 5); if not, continue to determine whether the Gm data is valid, if so, proceed to step 5); if not, output fault information; 5) Determine whether the Am1 data is valid, if valid, proceed to step 6); if invalid, continue to determine whether the Am2 data is valid, if valid, proceed to step 6); if invalid, output fault information; 6) Determine whether the GNSS data is valid. If it is valid, perform integrated navigation solution. If it is invalid, perform pure inertial navigation solution. 7) Output the solution data.

[0010] Furthermore, the working process of the second navigation module includes the following steps: 1) Initialize after powering on, and then collect the Gm data of the MEMS gyroscope and the Am2 data of the MEMS accelerometer; 2) Receive data from the first navigation module to obtain data from the three-axis fiber optic gyroscope Gf and data from the three-axis accelerometer Am1; 3) Receive data from the GNSS satellite guidance module; 4) Determine whether the Gm data is valid. If so, proceed to step 5); if not, continue to determine whether the Gg data is valid. If so, proceed to step 5); if not, output fault information; 5) Determine whether the Am2 data is valid, if valid, proceed to step 6); if not valid, continue to determine whether the Am1 data is valid, if valid, proceed to step 6); if not valid, output fault information; 6) Determine whether the GNSS data is valid. If so, perform combined navigation solution; if not, perform pure inertial navigation solution and determine whether the first navigation module is valid. If so, use the first navigation module's attitude and velocity data for Kalman filter compensation; 7) Output the solution data.

[0011] Compared with the prior art, the present invention has the following advantages: 1. IMU integration and integrated design reduce volume and improve accuracy: Since the three-axis orthogonal configuration of the fiber optic gyroscope sensitive ring naturally forms an internal cavity, it is generally not used except for the placement of accelerometers (the placement of circuit board cards will cause the temperature characteristics of the fiber optic gyroscope to deteriorate), and the integrated design can make full use of the space to place MEMS gyroscopes and MEMS accelerometers, thereby making full use of space and reducing volume. The integrated design also makes the center of mass of the fiber optic gyroscope / MEMS gyroscope coincide as much as possible, reducing the internal rod arm, so that when the inertial device fails, the two navigation modules can easily use the data of the remaining devices without considering additional errors.

[0012] 2. The dual navigation module integrated design is adopted, and the GNSS satellite navigation module PPS synchronous fiber optic gyro IMU and MEMS IMU are used for acquisition to minimize the impact of delay on the system. When the inertial device fails, the navigation module 1 / 2 can seamlessly switch the data source, which reduces the volume and improves the system accuracy.

[0013] 3. The integrated design of the whole machine reduces the size of the whole machine compared to the traditional dual inertial navigation redundant backup design. During the production process, the calibration and testing of two IMUs can be completed at one time, which reduces the number of processes and greatly reduces the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a principle block diagram of the present invention.

[0015] Figure 2 It is a schematic diagram of the assembly structure of the present invention.

[0016] Figure 3 This is the workflow diagram of the first navigation module.

[0017] Figure 4 This is the workflow diagram of the second navigation module. DETAILED DESCRIPTION

[0018] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0019] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. In the description of the present invention, it should be noted that the orientation or position relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the invention product is usually placed when used, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance. In addition, the terms "horizontal", "vertical", etc. do not mean that the components are absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted. In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0021] Example: See Figure 1 , Figure 2 An integrated fusion navigation system based on MEMS and fiber optic gyroscope includes a three-axis fiber optic gyroscope, a three-axis accelerometer, a three-axis MEMS gyroscope, a three-axis MEMS accelerometer, a GNSS satellite navigation module, and a first navigation module and a second navigation module. The data output ends of the three-axis fiber optic gyroscope and the three-axis accelerometer are connected to the first navigation module, and the data output ends of the three-axis MEMS gyroscope and the three-axis MEMS accelerometer are connected to the second navigation module. The data output end of the GNSS satellite navigation module is connected to the first navigation module and the second navigation module at the same time, and the first navigation module and the second navigation module are connected to each other, wherein the first navigation module and the second navigation module use the data collected by the PPS synchronous fiber optic gyroscope IMU and MEMS IMU to achieve mutual connection. During implementation, a power supply module is also included to power each electrical component.

[0022] During actual assembly, the three-axis fiber optic gyroscope includes an IMU bracket, and the three-axis sensitive elements of the three-axis fiber optic gyroscope are respectively installed on the X, Y, and Z corresponding sides of the IMU bracket. The three-axis accelerometer, three-axis MEMS gyroscope, and three-axis MEMS accelerometer are all installed in the IMU bracket, and the GNSS satellite navigation module can be installed on the IMU bracket or the housing according to the product appearance requirements. Since the three-axis orthogonal configuration of the fiber optic gyroscope sensitive ring naturally forms an internal cavity, it is generally not used except for placing the accelerometer (the placement of the circuit board card causes the temperature characteristics of the fiber optic gyroscope to deteriorate), and the integrated design can make full use of the space to place the MEMS gyroscope and the MEMS accelerometer, thereby making full use of the space and reducing the volume; the integrated integrated design also allows the center of mass of the fiber optic gyroscope / MEMS gyroscope to coincide as much as possible, reducing the internal lever arm, so that when the inertial device fails, the two navigation modules can easily use the data of the remaining devices without considering additional errors.

[0023] The first navigation module and the second navigation module are connected to each other and respectively solve the received data and output a full set of navigation data for use by a host computer such as a flight control system. The host computer selects one of them for use according to the state of the navigation system and its own task judgment.

[0024] Through the above design, the integrated design of the whole machine reduces the size of the whole machine compared to the traditional dual inertial navigation redundant backup design. During the production process, the calibration and testing of two IMUs can be completed at one time, which reduces the number of processes and greatly reduces the production cost.

[0025] In this proposal, see Figure 3 The working process of the first navigation module includes the following steps: 1) After powering on, it is initialized and then the data of the three-axis fiber optic gyroscope Gf and the three-axis accelerometer Am1 are collected; 2) Receive data from the second navigation module to obtain Gm data of the MEMS gyroscope and Am2 data of the MEMS accelerometer; 3) Receive data from the GNSS satellite guidance module; 4) Determine whether the Gf data is valid, if so, proceed to step 5); if not, continue to determine whether the Gm data is valid, if so, proceed to step 5); if not, output fault information; 5) Determine whether the Am1 data is valid, if valid, proceed to step 6); if invalid, continue to determine whether the Am2 data is valid, if valid, proceed to step 6); if invalid, output fault information; 6) Determine whether the GNSS data is valid. If it is valid, perform integrated navigation solution. If it is invalid, perform pure inertial navigation solution. 7) Output the solution data.

[0026] In this proposal, see Figure 4 The working process of the second navigation module includes the following steps: 1) Initialize after powering on, and then collect the Gm data of the MEMS gyroscope and the Am2 data of the MEMS accelerometer; 2) Receive data from the first navigation module to obtain data from the three-axis fiber optic gyroscope Gf and data from the three-axis accelerometer Am1; 3) Receive data from the GNSS satellite guidance module; 4) Determine whether the Gm data is valid. If so, proceed to step 5); if not, continue to determine whether the Gg data is valid. If so, proceed to step 5); if not, output fault information; 5) Determine whether the Am2 data is valid, if valid, proceed to step 6); if not valid, continue to determine whether the Am1 data is valid, if valid, proceed to step 6); if not valid, output fault information; 6) Determine whether the GNSS data is valid. If so, perform combined navigation solution; if not, perform pure inertial navigation solution and determine whether the first navigation module is valid. If so, use the first navigation module's attitude and velocity data for Kalman filter compensation; 7) Output the solution data.

[0027] Under normal working conditions, 1) Navigation module 1 collects sensitive angular rate and acceleration information of fiber optic gyroscope and accelerometer 1, receives satellite navigation information sent by GNSS satellite navigation module, and realizes integrated navigation; Navigation module 1 receives IMU information sent by navigation module 2, but does not participate in navigation solution; 2) Navigation module 2 collects angular rate and acceleration information sensitive to MEMS accelerometer and MEMS gyroscope information, receives satellite navigation information sent by GNSS satellite navigation module, and realizes integrated navigation; Navigation module 2 receives IMU information sent by navigation module 1, calibrates MEMS data, and can greatly improve the accuracy of MEMS navigation output. Both output navigation information and status information for use by the host computer.

[0028] 3) The data between the two navigation modules are synchronized through the PPS signal of the GNSS satellite navigation module.

[0029] When any inertial device fails, navigation module 1 / 2 can perform navigation calculations based on the data from the remaining inertial devices, improving overall reliability and avoiding overall failure of the inertial navigation. For example, when a MEMS gyroscope fails: 1) Navigation module 1 works normally; 2) Navigation module 2 collects MEMS accelerometer information, receives fiber optic gyroscope data sent by navigation module 1, and completes navigation solution; receives satellite navigation information sent by GNSS satellite navigation module to realize combined navigation.

[0030] 3) Navigation modules 1 / 2 both output navigation information, and the overall machine availability rate is 100%.

[0031] Similarly, when accelerometer 1 fails: 1) Navigation module 1 collects fiber optic gyroscope information, receives MEMS accelerometer data sent by navigation module 2, and completes navigation solution; receives satellite navigation information sent by GNSS satellite navigation module to realize integrated navigation.

[0032] 2) Navigation module 2 works normally; 3) Navigation modules 1 / 2 both output navigation information, and the overall machine availability rate is 100%.

[0033] When navigation module 1 or 2 fails, the whole machine degenerates into the traditional dual INS redundant backup mode where one of the INS fails.

[0034] This solution integrates the dual navigation modules and uses the GNSS satellite navigation module PPS synchronous fiber optic gyro IMU and MEMS IMU to collect data, thereby minimizing the impact of latency on the system. When an inertial device fails, navigation module 1 / 2 can seamlessly switch data sources, reducing the size and improving system accuracy.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the technical solution. Those skilled in the art should understand that those modifications or equivalent substitutions of the technical solution of the present invention that do not depart from the purpose and scope of the technical solution should be included in the scope of the claims of the present invention.

Claims

1. An integrated fusion navigation system based on MEMS and fiber optic gyroscope, characterized by: The system comprises a three-axis fiber optic gyroscope, a three-axis accelerometer, a three-axis MEMS gyroscope, a three-axis MEMS accelerometer, a GNSS satellite navigation module, a first navigation module and a second navigation module; wherein the data output ends of the three-axis fiber optic gyroscope and the three-axis accelerometer are connected to the first navigation module, the data output ends of the three-axis MEMS gyroscope and the three-axis MEMS accelerometer are connected to the second navigation module, the data output end of the GNSS satellite navigation module is connected to the first navigation module and the second navigation module at the same time, and the first navigation module and the second navigation module are connected to each other; the first navigation module and the second navigation module are connected to each other to respectively solve the received data and then output the navigation data respectively for use by the host computer, and the host computer selects one of them to use according to the navigation system status bit and its own task.

2. The integrated fusion navigation system based on MEMS and fiber optic gyroscope according to claim 1 is characterized in that: The three-axis fiber optic gyroscope includes an IMU bracket, and the three-axis sensitive elements of the three-axis fiber optic gyroscope are respectively installed on the X, Y, and Z corresponding sides of the IMU bracket; the three-axis accelerometer, three-axis MEMS gyroscope, and three-axis MEMS accelerometer are all installed in the IMU bracket, and the GNSS satellite navigation module is installed on the IMU bracket or the shell.

3. The integrated fusion navigation system based on MEMS and fiber optic gyroscope according to claim 1 is characterized in that: The working process of the first navigation module includes the following steps: 1) After powering on, it is initialized and then the data of the three-axis fiber optic gyroscope Gf and the three-axis accelerometer Am1 are collected; 2) Receive data from the second navigation module to obtain Gm data of the MEMS gyroscope and Am2 data of the MEMS accelerometer; 3) Receive data from the GNSS satellite guidance module; 4) Determine whether the Gf data is valid, if so, proceed to step 5); if not, continue to determine whether the Gm data is valid, if so, proceed to step 5); if not, output fault information; 5) Determine whether the Am1 data is valid, if valid, proceed to step 6); if invalid, continue to determine whether the Am2 data is valid, if valid, proceed to step 6); if invalid, output fault information; 6) Determine whether the GNSS data is valid. If it is valid, perform combined navigation solution. If it is invalid, perform pure inertial navigation solution. 7) Output the solution data.

4. The integrated fusion navigation system based on MEMS and fiber optic gyroscope according to claim 1 is characterized in that: The working process of the second navigation module includes the following steps: 1) Initialize after powering on, and then collect the Gm data of the MEMS gyroscope and the Am2 data of the MEMS accelerometer; 2) Receive data from the first navigation module to obtain data from the three-axis fiber optic gyroscope Gf and data from the three-axis accelerometer Am1; 3) Receive data from the GNSS satellite guidance module; 4) Determine whether the Gm data is valid. If so, proceed to step 5); if not, continue to determine whether the Gg data is valid. If so, proceed to step 5); if not, output fault information; 5) Determine whether the Am2 data is valid, if valid, proceed to step 6); if not valid, continue to determine whether the Am1 data is valid, if valid, proceed to step 6); if not valid, output fault information; 6) Determine whether the GNSS data is valid. If so, perform combined navigation solution; if not, perform pure inertial navigation solution and determine whether the first navigation module is valid. If so, use the first navigation module's attitude and velocity data for Kalman filter compensation; 7) Output the solution data.

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