CN211698218U - High-precision navigation system combining precise point positioning and inertial navigation system - Google Patents
High-precision navigation system combining precise point positioning and inertial navigation system Download PDFInfo
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Abstract
The utility model provides a high accuracy navigation of accurate point location and inertial navigation system combination. The high-precision navigation system comprises: the navigation terminal device comprises an inertia sensing unit, a satellite positioning receiver, a processing module and a wireless transmission module, wherein the inertia sensing unit obtains inertia observation data, the satellite positioning receiver obtains satellite observation data, and the wireless transmission module transmits the satellite observation data through a wireless network. And the navigation server receives satellite observation data from the navigation terminal equipment, calculates satellite navigation data of the navigation terminal equipment based on the satellite observation data, and transmits the satellite navigation data back to the navigation terminal equipment through a wireless network. Thus, the utility model provides a navigation terminal equipment can provide high accuracy navigation service that can be high with very low cost.
Description
Technical Field
The utility model relates to a navigation especially relates to a high accuracy navigation of accurate point location and inertial navigation system combination.
Background
The combination of precision Point location (PPP) and Inertial Navigation System (INS) is an effective high-precision location technology route for low-cost automobile consumer market. PPP is based on a multi-band Global Navigation Satellite System (GNSS) and high-precision satellite State Space correction (SSR), and is widely applied to the field of real-time high-precision positioning. However, the continuity and reliability of such high-precision GNSS positioning may be significantly degraded in a poor observation environment, resulting in erroneous determination by the autopilot system. The INS performs navigation based on the inertial sensing unit, is not interfered by external signals or shielding, and can overcome the defects of PPP. Since the errors of the gyroscopes and accelerometers in the inertial sensing unit can accumulate over time, the accuracy of the INS can also degrade significantly over time. The PPP and INS combined system overcomes the defects of a single system through the combination of the observation values of the GNSS and the INS, and improves the positioning accuracy, reliability and usability. However, the implementation of the combined PPP and INS system in a low-cost terminal will face the following difficulties:
1) the SSR correction data are generally broadcast through an L wave band of a communication satellite or a wireless network, and under the condition of poor satellite signal observation conditions, the SSR correction data are influenced to be received;
2) the navigation terminal device must support communication satellite L-band decoding protocol and Ntrip protocol, rtcm (radio technical Commission for landmark services) information format, SSR correction data decoding and corresponding orbit, clock error and pseudorange phase deviation calculation. The typical RTCM3 packet types and contents are shown in the following table:
3) complex data processing algorithms such as PPP-related error correction calculation, ambiguity fixing, Kalman (Kalman) filtering combination, and the like require a large amount of computing power and power consumption;
4) at present, because the number of signal channels is limited, the number of dual-frequency observed values cannot be ensured on the premise of ensuring multiple systems, and the influence of ionospheric delay cannot be eliminated through dual-frequency ionospheric independent combination.
5) The correct fixing of the ambiguity plays a crucial role in PPP convergence. For survey grade GNSS receivers, PPP technology typically requires 15-30 minutes to converge to within 10 centimeters of the positioning accuracy requirements of the drone, i.e., horizontal. For low-cost devices, the ambiguity fixing will be more difficult, so the PPP convergence time and the accuracy after the PPP convergence are a core problem to be solved. Traditional ambiguity fixing typically uses the LAMBDA method to perform ambiguity decorrelation and integer ambiguity search after the floating ambiguity reaches a certain precision. Two sets of integer ambiguity combinations were obtained and subjected to ratio detection. The combination of ambiguities considered optimal if detected can be fixed. In practice, however, some slight ambiguity bias may result in undetectable radio, resulting in convergence of the PPP location.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to provide a high accuracy navigation of accurate point location and inertial navigation system combination, it can make low-cost navigation terminal equipment provide reliable high accuracy navigation service.
To achieve the object, according to one aspect of the present invention, the present invention provides a high precision navigation system combining precise point positioning and an inertial navigation system, comprising: the navigation terminal device comprises an inertia sensing unit, a satellite positioning receiver, a processing module and a wireless transmission module, wherein the inertia sensing unit obtains inertia observation data, the inertia observation data comprise acceleration sensing data and angular velocity sensing data, the processing module calculates the acceleration sensing data and the angular velocity sensing data to obtain inertia position variation and inertia velocity variation, obtains a current inertia position based on the previous inertia position and inertia position variation, obtains a current inertia velocity based on the previous inertia velocity and inertia velocity variation, the satellite positioning receiver obtains satellite observation data, the satellite observation data comprise a pseudo-range observation value, a phase observation value and a Doppler observation value, and the wireless transmission module transmits the satellite observation data through a wireless network; a navigation server for receiving satellite observation data from the navigation terminal device, calculating satellite navigation data of the navigation terminal device based on the satellite observation data, and transmitting the satellite navigation data back to the navigation terminal device through a wireless network, wherein the satellite navigation data comprises a satellite navigation position and a satellite navigation speed, wherein the processing module of the navigation terminal device obtains the current integrated navigation position by taking the satellite navigation position as a reference and combining the current inertial position, the current combined navigation speed is obtained by taking the satellite navigation speed as a reference and combining the current inertial navigation speed, the sample rate of the satellite observation data is lower than the sample rate of the inertial observation data, the sample rate of the satellite observation data refers to the number of the satellite observation data obtained per second, and the sample rate of the inertial observation data refers to the number of the inertial observation data obtained per second.
Compared with the prior art, the utility model provides a navigation terminal equipment can provide high accuracy navigation service that can be high with very low cost.
Drawings
Fig. 1 is a schematic structural diagram of a high-precision navigation system according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a navigation terminal device according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a navigation server according to an embodiment of the present invention.
Detailed Description
To further illustrate the technical means and effects of the present invention adopted to achieve the predetermined objects, the following detailed description of the embodiments, structures, features and effects according to the present invention will be given with reference to the accompanying drawings and preferred embodiments.
The utility model provides a high accuracy navigation of accurate point location and inertial navigation system combination can be based on this kind of structure high accuracy navigation and operate on the navigation terminal equipment of low cost (for example 50 dollars) to can provide reliable high accuracy navigation service, for example positioning accuracy will reach within 10 centimetres, and then support autopilot's navigation.
Fig. 1 is a schematic structural diagram of a high-precision navigation system 100 according to an embodiment of the present invention. The high-precision navigation system 100 includes a navigation terminal device 102 and a navigation server 106.
The navigation terminal apparatus 102 may be plural. The navigation terminal device 102 can be mounted on a motor vehicle, so as to perform high-precision navigation on driving navigation, especially unmanned navigation, of the motor vehicle. The navigation terminal 102 can communicate with the navigation server 106 via a wireless network 104. Wireless network 104 can be 2G, 3G, 4G or 5G network, also can be the combination of a plurality of networks, for example bluetooth +4G, Wifi + internet +5G etc. the utility model discloses to wireless network 104's concrete type does not have the requirement, as long as can support stable communication can.
Fig. 2 is a schematic structural diagram of the navigation terminal 102 according to an embodiment of the present invention. The navigation terminal device 102 includes an inertial sensing unit 210, a satellite positioning receiver 220, a processing module 230, and a wireless transmission module 240. The inertial sensing unit 210 obtains inertial observation data. The inertial sensing unit 210 includes an acceleration sensor 211 and a gyroscope 212, and the inertial observation data includes accelerometer dataAcceleration sensing data obtained by the velocity sensor 211 and angular velocity sensing data obtained by the gyroscope 212. The processing module 230 calculates the acceleration sensing data and the angular velocity sensing data to obtain the inertial position variation prAnd the amount of change v of the inertial velocityrBased on the previous inertial position and the amount of change p in the inertial positionrObtaining the current inertia position based on the previous inertia speed and the inertia speed variation vrAnd obtaining the current inertia speed. The satellite positioning receiver 220 obtains satellite observation data, which includes a pseudorange observation value, a phase observation value, and a doppler observation value.
In one embodiment, the wireless transmission module 230 transmits the satellite observations over the wireless network 104. The navigation terminal 102 may be one device packaged in one box, or may be two or more devices packaged in two or more independent boxes, and these devices operate in combination to realize the function of the navigation terminal 102. When implemented, the wireless transmission module 240 may be located in the same box as other modules, or may be located in a different box from other modules.
The navigation server 106 receives satellite observation data from the navigation terminal device 102, calculates satellite navigation data of the navigation terminal device 102 based on the satellite observation data, and transmits the satellite navigation data to the navigation terminal device 102 through the wireless network 104, where the satellite navigation data includes a satellite navigation position and a satellite navigation speed.
The processing module 230 of the navigation terminal device 102 obtains the current integrated navigation position by combining the current inertial position with the satellite navigation position as a reference, and obtains the current integrated navigation speed by combining the current inertial navigation speed with the satellite navigation speed as a reference. The sample rate of the satellite observation data is lower than the sample rate of the inertial observation data, the sample rate of the satellite observation data refers to the number of the satellite observation data obtained per second, and the sample rate of the inertial observation data refers to the number of the inertial observation data obtained per second. In particular, the sample rate of the satellite observations is typically 1-10, i.e. 1-10 satellite observations are obtained per second, such as 1, and the sample rate of the inertial observations is 50-1000, i.e. 50-1000 inertial observations are obtained per second, such as 100.
In a preferred embodiment, the wireless transmission module 240 further transmits the inertial observation data to the navigation server 106 through a wireless network, and at this time, the navigation server 106 calculates satellite navigation data of the navigation terminal device 102 by combining the inertial observation data and the satellite observation data. In another alternative embodiment, the wireless transmission module 240 further transmits the inertial position variation and the inertial velocity variation to the navigation server 106 via a wireless network, and the navigation server 106 calculates satellite navigation data of the navigation terminal 102 by combining the inertial position variation, the inertial velocity variation and the satellite observation data. The navigation server 104 may also obtain attitude information according to the inertial observation data, or the inertial position variation and the inertial speed variation, and the navigation server 104 transmits the attitude information back to the navigation terminal device 102 for navigation.
Since the PPP/INS combined positioning core algorithm is implemented on the navigation server 106, the navigation terminal device 102 only needs to transmit observation data back to the navigation server 106 through a wireless network, and final satellite navigation data is transmitted back to the navigation server 106 after the operation of the navigation server 106 is completed. In this way, the navigation terminal device 102 does not involve the calculation related to positioning and the subsequent data processing with large calculation amount, so that the calculation capability and power consumption requirements of the navigation terminal device can be greatly reduced, and the cost of the navigation terminal device 102 can be reduced as much as possible.
The utility model provides a high accuracy navigation 100 can be used for autopilot, also can be used for other applications of other high accuracy navigation.
The high-precision navigation system 100 can support four systems, i.e., GPS, GLONASS (GLONASS), galileleo (galileo), and BEIDOU (BEIDOU).
In one embodiment, the navigation server 106 calculates the satellite navigation data of the navigation terminal apparatus 102 based on the inertial position variation, the inertial velocity variation, and the satellite observation data by the following calculation. Fig. 3 is a schematic structural diagram of the navigation server 106 according to an embodiment of the present invention.
The PPP observed value model is as follows
In equations (1), (2) and (3), P, L and D represent GNSS pseudoranges, phases and doppler observations, respectively; subscripts j and s are frequency and satellite PRN number, respectively; p is a position; v is the velocity; c is the speed of light; t is a clock difference; r is a receiver and d is pseudo range deviation; u is a phase deviation; t is tropospheric delay; i is ionospheric delay; and N is the ambiguity. Δ P and Δ L are the various error corrections of pseudorange and phase. Is an observed value error.
For the four systems of GPS, GLONASS, GALILEO and BEIDOU, the PPP model state parameters are:
the observed value model of INS is:
in formulae (5) to (7), SgAnd SaCoefficient errors of the gyroscope and the accelerometer respectively; b isgAnd BaZero bias for the gyroscope and accelerometer respectively.
And
respectively representing theoretical and actual angular velocity observed values;
and fbRespectively representing theoretical and actual acceleration observed values;
converting a matrix from an INS coordinate system to a navigation coordinate system;
is the angular velocity of the inertial system relative to the ECEF coordinate system;
is the ECEF coordinate system relative to the navigation coordinate system; gnIs the gravitational acceleration under the navigation coordinate system.
The velocity, position and rate of change of the coordinate transformation matrix. From equation (7), p can be obtainedr，vrThus, the position speed at the current moment is obtained:
pr,INS＝pr,k-1+pr,k(8)
vr,INS＝vr,k-1+vr,k(9)
the tight combination observation model is as follows:
the state parameters of the combined navigation model are as follows:
in a preferred embodiment, the navigation server 106 performs interactive detection on the high-precision satellite state space correction SSR correction data based on satellite observation data transmitted from a plurality of navigation terminal devices to correct the high-precision satellite state space correction. And the navigation server carries out interactive detection on the satellite navigation data of one or more navigation terminal devices and the satellite navigation data of another navigation terminal device. The specific application scenarios are as follows: 1) on the basis of the ionosphere model, if the position of the terminal equipment in the region is converged, the ionosphere inclined direction delay corresponding to the equipment observation value can be calculated to detect and correct the ionosphere model; 2) if another terminal device data is found to be transmitted back to the server in the vicinity of one terminal device, the precision point positioning mode can be directly switched to an RTK (real time kinematic) model to accelerate the convergence of the position information.
In a preferred embodiment, the navigation server receives SSR correction data in RTCM format from other data sources, and the navigation server calculates satellite navigation data of the navigation terminal device based on the SSR correction data and satellite observation data in RTCM format from the navigation terminal device.
In one embodiment, to reduce the cost, the navigation terminal device 102 can only provide single-frequency satellite observation data, and the navigation server 106 needs to estimate the ionospheric delay in calculating the satellite navigation data of the navigation terminal device 102 based on the satellite observation data. Preferably, the navigation server 106 adopts a global ionosphere model as a correction when estimating the ionosphere delay to estimate the ionosphere slant direction delay and constrain the ionosphere slant direction delay to estimate the ionosphere delay, so as to ensure the positioning accuracy and the convergence time of the precise point positioning.
The method for estimating the ionospheric diagonal delay and constraining the ionospheric diagonal delay by adopting the global ionospheric model as correction specifically comprises the following steps:
wherein vtec is the number of ionosphere electrons in the vertical direction; n and M are respectively ionized layer spherical harmonic function series and order; cnmAnd SnmAre spherical harmonic coefficients respectively; λ s is the average daily fixed point longitude;
the ionospheric puncture point latitude; kappajIs a frequency coefficient;
is the ionospheric projection coefficient, PnmIs an integral legendre function.
The ionospheric delay constraint function is,
in one embodiment, the navigation server 106 needs to perform ambiguity fixing in the process of calculating the satellite navigation data of the navigation terminal device 102 based on the satellite observation data. The navigation server 106 adopts an integer ambiguity weighted average strategy when the ambiguity is fixed, performs ambiguity decorrelation and integer ambiguity combination search by using an LAMBDA method after the floating ambiguity reaches a predetermined precision, calculates the weight of the ambiguity combination according to the residual square sum of the searched integer ambiguity and the corresponding floating ambiguity, obtains n groups of optimal ambiguity combinations and weights thereof to calculate the weighted average ambiguity, and directly fixes the weighted average ambiguity if the interpolation of the weighted average ambiguity and the integer is less than a predetermined threshold, such as 0.001.
In one embodiment, the navigation terminal device 102 sends the satellite observation data to the navigation server 106 in rtcm3 format at a frequency of 1 Hz. The navigation terminal device 102 calculates p in formulas (5) to (7) as well as p in formulas (8) and (9)r，vrAnd sending the information to the navigation server.
The navigation server receives, decodes satellite observation data, broadcasts ephemeris, SSR corrections, and GNSS error corrections needed to compute PPP.
The corresponding information can be obtained after decoding by the RTCM3, and the specific corresponding corrections of other information besides the satellite orbit and clock error can be found in equations (1) - (3).
The RTCM3 track clock error correction information is as follows:
ΔSSR(IODE,t0)＝(Or,Oa,Oc,O′r,O'a,O′c,C0,C1,C2) (15)
o in formulae (15) to (17)r,Oa,Oc,O′r,O'a,O′c,C0,C1,C2Radial, tangential and normal orbital corrections and correction number rates of change, correction of clock error and correction rates and accelerations, respectively.
t＝C0+C1(t-t0)+C2(t-t0)2(18)
Δts＝Δtb-t/c (19)
The user position, velocity, time, attitude information, GNSS related status information (atmospheric error, floating ambiguity, etc.) and INS related status information (accelerometer and gyroscope biases and scale factors, etc.) are then obtained by the calculations of equations (1) - (14). After the reliable floating ambiguity is obtained, the ambiguity is updated by adopting the integer ambiguity weighted average strategy. And obtaining the result after the ambiguity is updated.
According to another aspect of the present invention, the present invention can be implemented as a high-precision navigation method combining precise point positioning and an inertial navigation system. The high-precision navigation method comprises the following steps: the method comprises the steps that an inertia sensing unit of the navigation terminal equipment obtains inertia observation data, the inertia observation data comprise acceleration sensing data and angular velocity sensing data, a processing module of the navigation terminal equipment calculates the acceleration sensing data and the angular velocity sensing data to obtain inertia position variation and inertia velocity variation, a current inertia position is obtained based on a previous inertia position and the inertia position variation, and a current inertia velocity is obtained based on the previous inertia velocity and the inertia velocity variation; a satellite positioning receiver of the navigation terminal equipment obtains satellite observation data, wherein the satellite observation data comprises a pseudo-range observation value, a phase observation value and a Doppler observation value; the wireless transmission module of the navigation terminal equipment transmits the satellite observation data through a wireless network; the navigation server receives satellite observation data from the navigation terminal equipment, calculates satellite navigation data of the navigation terminal equipment based on the satellite observation data, and transmits the satellite navigation data back to the navigation terminal equipment through a wireless network, wherein the satellite navigation data comprises a satellite navigation position and a satellite navigation speed, wherein the processing module of the navigation terminal device obtains the current integrated navigation position by taking the satellite navigation position as a reference and combining the current inertial position, the current combined navigation speed is obtained by taking the satellite navigation speed as a reference and combining the current inertial navigation speed, the sample rate of the satellite observation data is lower than the sample rate of the inertial observation data, the sample rate of the satellite observation data refers to the number of the satellite observation data obtained per second, and the sample rate of the inertial observation data refers to the number of the inertial observation data obtained per second.
For details of implementation of the high-precision navigation method, reference may be made to the above high-precision navigation system, which is not repeated here.
As used herein, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, including not only those elements listed, but also other elements not expressly listed.
In this document, the terms front, back, upper and lower are used to define the components in the drawings and the positions of the components relative to each other, and are used for clarity and convenience of the technical solution. It is to be understood that the use of the directional terms should not be taken to limit the scope of the claims.
The features of the embodiments and embodiments described herein above may be combined with each other without conflict.
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the present invention, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included within the protection scope of the present invention.
Claims (3)
1. A combined precision point location and inertial navigation system high precision navigation system comprising:
navigation terminal equipment, it includes: the inertial sensing unit is used for obtaining inertial observation data; a satellite positioning receiver for obtaining satellite observation data; the satellite positioning system comprises an inertial position sensing unit, a processing module and a wireless transmission module, wherein the inertial position sensing unit is used for calculating acceleration sensing data and angular velocity sensing data in inertial observation data to obtain inertial position variation and inertial velocity variation, obtaining a current inertial position based on a previous inertial position and inertial position variation, obtaining a current inertial velocity based on a previous inertial velocity and inertial velocity variation, and transmitting the satellite observation data out through a wireless network;
a navigation server for receiving satellite observation data from the navigation terminal device, calculating satellite navigation data of the navigation terminal device based on the satellite observation data, and transmitting the satellite navigation data back to the navigation terminal device through a wireless network, wherein the satellite navigation data comprises a satellite navigation position and a satellite navigation speed,
the processing module of the navigation terminal device obtains a current combined navigation position by taking the satellite navigation position as a reference and combining a current inertial position, obtains a current combined navigation speed by taking the satellite navigation speed as a reference and combining the current inertial navigation speed, wherein the sample rate of the satellite observation data is lower than the sample rate of the inertial observation data, the sample rate of the satellite observation data refers to the number of the satellite observation data obtained per second, and the sample rate of the inertial observation data refers to the number of the inertial observation data obtained per second.
2. The high accuracy navigation system of claim 1, wherein the wireless transmission module further transmits the inertial observation data to the navigation server via a wireless network, the navigation server calculates satellite navigation data of the navigation terminal device by combining the inertial observation data and the satellite observation data, or,
the wireless transmission module further transmits the inertial position variation and the inertial speed variation to the navigation server through a wireless network, and the navigation server calculates satellite navigation data of the navigation terminal device by combining the inertial position variation, the inertial speed variation and the satellite observation data.
3. The high accuracy navigation system of claim 1, wherein the navigation terminal device is installed on a motor vehicle, and the navigation terminal device performs driving navigation on the motor vehicle according to a current combined navigation position and the current combined navigation speed.
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