JP2006189320A - Positioning calculator, positioning device, and positioning calculation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve positioning accuracy, reception sensitivity, and extrapolation accuracy when positioning is interrupted in a satellite navigation system.
In an arithmetic unit 300, an observation amount correction unit 330 outputs a distance between a satellite and a receiver based on a pseudorange and a Doppler amount output from a GPS receiver and a rate of change in distance as an observation value. The relative motion calculation unit 340 outputs the distance based on the moving body position / velocity, which is the previous positioning calculation result, and the distance change rate as calculated values. The residual calculation unit 350 outputs the difference between the observed value and the calculated value as a residual. The positioning calculation unit 370 performs positioning calculation by Kalman filter processing based on the residual and the clock error. In this Kalman filter process, the clock error is a tertiary system of clock bias, clock drift, and clock bias acceleration. The clock reset detection / compensation unit 360 is also characterized in that the clock error is processed in a tertiary system in the compensation process of the clock error accompanying the clock reset of the receiver.
[Selection] Figure 4

Description

  The present invention relates to a positioning calculator, a positioning device, and a positioning calculation method in a satellite navigation system.

In GPS (Global Positioning System) / GNSS (Global Navigation Satellite System) receivers, the distance measured after measuring the propagation time between the satellite and the receiver and multiplying the propagation time by the speed of light. Perform positioning calculation using information. The reference signal used for the propagation time measurement is generated by a clock in the receiver. Therefore, an extremely stable clock is required to accurately measure the position and speed. Therefore, a high-accuracy crystal clock with temperature compensation (TCXO: Temperature Compensated Xtal Oscillator) is used in a high-performance receiver.
Further, the clock bias and the clock drift are estimated and compensated by a Kalman filter or the like (Non-Patent Document 1).
Introduction to Random Signals and Applied Kalman Filtering, 3rd Edition, R.M. G. Brown and P.M. Y. C. Hwang, John Wiley & Sons, 1997

However, since TCXO is relatively expensive, it is desirable in terms of cost to use XO without temperature compensation. However, in this case, the performance of positioning accuracy, sensitivity, and extrapolation accuracy when positioning is interrupted is degraded.
Further, when the clock bias error becomes excessive and synchronization with the GPS time cannot be achieved, the receiver performs time alignment by resetting the clock. At this time, in a receiver using an inexpensive crystal oscillator (XO), the clock drift and the rate of change of the rate are large, so discontinuity occurs in the speed and position at the time of reset.

The present invention has been made in order to solve the above-described problems. Even when a positioning signal is received by a receiver using a low-accuracy clock such as XO without temperature compensation, positioning accuracy is improved. The purpose is to be able to improve.
It is another object of the present invention to improve the receiving sensitivity of the receiver.
It is another object of the present invention to improve positioning accuracy with respect to positioning by extrapolation performed when reception of a positioning signal is interrupted.
It is another object of the present invention to reduce the discontinuity of the position and speed of the moving object calculated even when the receiver clock is reset.

  The positioning calculator of the present invention includes a clock error included in the receiver, a clock bias indicating a positioning target position error based on the clock error, and a clock drift and clock indicating a positioning target speed error based on the clock error. It is characterized by performing a positioning operation on a positioning target by performing a Kalman filter process expressed by a clock bias acceleration indicating an error of the positioning target acceleration based on the error of the positioning target.

According to the present invention, positioning accuracy can be improved even when positioning is performed by receiving a positioning signal with a receiver using a low-accuracy clock such as XO without temperature compensation.
Further, the receiving sensitivity of the receiver can be improved.
In addition, positioning accuracy can be improved for positioning by extrapolation performed when reception of positioning signals is interrupted.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram of a positioning device 100 according to the first embodiment.
In FIG. 1, the positioning device 100 includes a GPS receiver 200 and a calculator 300.
The GPS receiver 200 receives a positioning signal including GPS and GNSS navigation messages. Then, the pseudo distance from the GPS satellite that has transmitted the positioning signal is calculated based on the propagation time of the received positioning signal. Further, the relative speed in the distance direction from the GPS satellite is calculated as the Doppler amount based on the frequency of the received positioning signal.
In addition, the calculator 300 receives the pseudo distance, the Doppler amount, and the navigation message from the GPS receiver 200 and performs a positioning calculation.

FIG. 2 is a hardware configuration diagram of the positioning device 100, the GPS receiver 200, and the arithmetic unit 300 in the first embodiment.
In FIG. 2, the positioning device 100, the GPS receiver 200, and the arithmetic unit 300 include a CPU (Central Processing Unit) 911 that executes a program. However, the positioning device 100, the GPS receiver 200, and the arithmetic unit 300 may each include the CPU 911 and the following hardware, or may share the CPU 911 and the following hardware.
The CPU 911 is connected to the ROM 913, the RAM 914, the communication board 915, and the magnetic disk device 920 via the bus 912.
The RAM 914 is an example of a volatile memory. The ROM 913 and the magnetic disk device 920 are examples of a nonvolatile memory. These are examples of a storage device or a storage unit.
The communication board 915 is connected to a FAX machine, a telephone, a LAN, the Internet, and the like.
For example, the communication board 915 is an example of an information input unit and an example of an output unit.

  The magnetic disk device 920 stores an operating system (OS) 921, a program group 923, and a file group 924. The program group 923 is executed by the CPU 911 and the OS 921.

The program group 923 stores programs that execute functions described as “˜units” in the description of the embodiments described below. The program is read and executed by the CPU 911.
In the file group 924, in the description of the embodiment described below, “determination result of”, “calculation result of”, “processing result of”, “update result of”, “extrapolation result of” The result information described with an expression such as “is stored as“ ˜file ”.
In addition, the arrow portion of the flowchart described in the description of the embodiment described below mainly indicates input / output of data, and for the input / output of the data, the data is the magnetic disk device 920, FD (Flexible Disk cartridge), Recording is performed on an optical disc, a CD (compact disc), an MD (mini disc), a DVD (Digital Versatile Disk), and other recording media. Alternatively, it is transmitted through a signal line or other transmission medium.

  In addition, what is described as “unit” in the description of the embodiment described below may be realized by firmware stored in the ROM 913. Alternatively, it may be implemented by software alone, hardware alone, a combination of software and hardware, or a combination of firmware.

  In addition, a program for implementing the embodiment described below may be stored using a recording device using a magnetic disk device 920, FD, optical disk, CD, MD, DVD, or other recording medium.

FIG. 3 is a configuration diagram of the GPS receiver 200 according to the first embodiment.
3, the GPS receiver 200 includes a GPS antenna 210, an RF (Radio Frequency) front-end processing unit 220, an XO 230, an A / D (Analog / Digital) conversion unit 240, and a baseband chip processing unit 250.
In the GPS receiver 200, first, the GPS antenna 210 receives GPS and GNSS positioning signals.
Then, the XO 230 generates a reference signal of about 20 MHz, for example.
Next, the RF front end processing unit 220 performs high frequency analog processing on the received positioning signal. Specifically, since it is difficult to directly digitally process a positioning signal of about 1.5 GHz, mixing is performed using a reference signal generated by the XO 230, and a difference frequency signal is extracted. And the process which finally drops the frequency of a positioning signal to about 2 MHz-10 MHz is performed by performing a mixing process in multiple times.
Next, the A / D conversion unit 240 converts the positioning signal processed by the RF front end processing unit 220 from an analog signal to a digital signal. Before the A / D conversion, a filtering process may be performed to avoid the influence of aliasing or the like. In the filtering process, a SAW (Surface Acoustic Wave) filter is generally used as a high frequency filter.
The baseband chip processing unit 250 performs spectrum despreading on the digitally converted positioning signal. By performing the spectrum despreading, the carrier wave before the spectrum spread is extracted from the positioning signal transmitted by the spectrum spread by the GPS satellite. Next, the phase difference (chip time) between the carrier wave extracted by performing spectrum despreading and the reference signal generated by the XO 230 is detected. Then, the detected phase difference (positioning signal propagation time) is multiplied by the speed of light to calculate a pseudo distance between the GPS satellite that has transmitted the positioning signal and the GPS receiver 200. Further, the relative difference between the GPS satellite and the GPS receiver 200 in the pseudo-distance distance direction based on the Doppler frequency, with the frequency difference between the received positioning signal frequency and 1575.42 MHz being the reference frequency of the GPS L1 signal as the Doppler frequency. The speed is calculated as a Doppler amount.

FIG. 4 is a configuration diagram of the arithmetic unit 300 according to the first embodiment.
In FIG. 4, a calculator 300 includes a distance correction calculation unit 310, a satellite position / velocity calculation unit 320, an observation amount correction unit 330, a relative motion calculation unit 340, a residual calculation unit 350, a reset detection / compensation unit 360, and a positioning calculation unit. (Kalman filter) 370 is provided.
The arithmetic unit 300 receives the pseudo distance, the Doppler amount, and the navigation message from the GPS receiver 200, performs a positioning calculation by the positioning calculation unit 370, and the position and speed of the moving object that is the positioning target including the GPS receiver 200. And the XO 230 clock error generated by the GPS receiver 200 is output. Here, the calculator 300 inputs the moving body position, moving body speed, and clock error output from the positioning calculation unit 370 together with the pseudo distance, Doppler amount, and navigation message output from the GPS receiver 200 during the next positioning calculation. To perform positioning calculation. And the positioning accuracy is improved by this feedback processing.

  First, the satellite position / velocity calculation unit 320 receives a navigation message from the GPS receiver 200 and calculates a satellite position and a satellite speed based on the input navigation message.

The distance correction calculation unit 310 receives the navigation message output from the GPS receiver 200, the moving body position output from the positioning calculation unit 370, and the satellite position output from the satellite position / velocity calculation unit 320. The correction amount for each of the pseudo distance and the Doppler amount output by 200 is calculated.
The correction amount is for correcting an error included in the pseudo distance and Doppler amount calculated by the GPS receiver 200. Among the errors included in the pseudorange and the Doppler amount, there are errors due to the received positioning signal being affected by the ionosphere and troposphere, clock errors of GPS satellites, and clock errors of the XO 230 of the GPS receiver 200. . Then, the distance correction calculation unit 310 calculates an error due to the ionosphere and the troposphere and a clock error of the GPS satellite. The positioning error calculation unit 370 calculates the clock error of the GPS receiver 200, and the observation amount correction unit 330 inputs the calculation to the clock error.
Therefore, the distance correction calculation unit 310 first determines the elevation angle from the relative positional relationship of the mobile body with respect to the GPS satellites based on the mobile body position input from the positioning calculation unit 370 and the satellite position input from the satellite position / velocity calculation unit 320. Ask for. Further, the altitude at which the moving body is located is acquired from the moving body position. Also, ionospheric information is acquired from the navigation message output by the GPS receiver 200. Then, an error due to the ionosphere and the troposphere is calculated based on the elevation angle of the GPS satellite, the altitude of the moving object, information on the ionosphere, and the like. The calculation method of the error due to the ionosphere and the troposphere is described in, for example, “Global Positioning System: Theory and Applications Volume, 1996, AAAA, Parkinson, BW and Spikler, J”. The clock error of the GPS satellite is obtained from the navigation message.

Next, the observation amount correction unit 330 receives the pseudo distance and the Doppler amount from the GPS receiver 200, inputs the correction amount for each of the pseudo distance and the Doppler amount from the distance correction calculation unit 310, and receives the clock from the positioning calculation unit 370. Enter the error.
The clock error input from the positioning calculation unit 370 is indicated by a clock bias and a clock drift. The clock bias is a distance value obtained by multiplying the clock error time by the speed of light, and the clock drift is a speed value obtained by differentiating the clock drift with respect to time. is there.
Here, the pseudo distance input from the GPS receiver 200 is ρ, the Doppler amount is ρ ′, the correction amount for the pseudo distance input from the distance correction calculation unit 310 is Δρ, the correction amount for the Doppler amount is Δρ ′, and the positioning calculation unit 370. The clock bias of the clock error input from tcb is tcb and the clock drift is tcd.
Then, the positioning calculation unit 370 outputs ρ + Δρ + tcb as an observed value of the distance between the satellite and the moving object, and ρ ′ + Δρ ′ + tcd as an observed value of the distance change rate between the satellite and the moving object.

The relative motion calculation unit 340 inputs the satellite position and the satellite velocity from the satellite position / velocity calculation unit 320, and inputs the moving body position and the moving body speed from the positioning calculation unit 370. The distance between the satellite position and the moving body position is calculated as ρ _C , and the distance change rate between the satellite speed and the moving body speed (relative speed in the distance direction between the satellite and the moving body) is calculated as ρ ′ _C and output. To do.

Next, the residual calculation unit 350 inputs the observation value ρ + Δρ + tcb of the distance between the satellite and the moving object and the observation value ρ ′ + Δρ ′ + tcd of the distance change rate between the satellite and the moving object from the observation amount correction unit 330, The calculated value ρ _C of the distance between the satellite and the moving object and the calculated value of the distance change rate ρ ′ _C between the satellite and the moving object are input from the motion calculation unit 340. Then, the difference between the observed value and the calculated value is calculated and output as a residual. That is, the residual of the distance between the satellite and the moving body is (ρ + Δρ + tcb) −ρ _C , and the residual of the distance change rate between the satellite and the moving body is (ρ ′ + Δρ ′ + tcd) −ρ ′ _C.
The residual calculation unit 350 receives the clock error from the observation amount correction unit 330 and outputs the input clock error.

Next, the reset detection / compensation unit 360 inputs the residual and the clock error from the residual calculation unit 350.
Here, it is assumed that the arithmetic unit 300 stores a threshold value for determining whether or not the clock is reset in the GPS receiver 200 in the storage unit. For example, corresponding to 1 msec which is the period of the GPS C / A code, 300 km which is an approximate distance obtained by multiplying 1 msec by the speed of light is stored as a threshold value. However, the threshold value may be another value, for example, a value based on specifications related to clock reset of the GPS receiver 200.
Then, the reset detection / compensation unit 360 compares the threshold stored in the storage unit with the residual of the distance input from the residual calculation unit 350. If the residual is larger than the threshold, the GPS receiver 200 It is determined that a reset has been performed. However, the reset detection / compensation unit 360 may acquire information on the presence / absence of reset directly from the GPS receiver 200 and determine the presence / absence of reset based on the acquired information.

  If the reset detection / compensation unit 360 determines that the clock has been reset in the GPS receiver 200, the reset detection / compensation unit 360 calculates the following Equation 1 to correct the clock error and perform compensation for the reset.

  In the above Equation 1, tcb, k represents a clock bias at a certain observation (k), tcd, k represents a clock drift at a certain observation, and tca, k represents a clock drift at a certain observation in time. Indicates the differentiated acceleration value (clock bias acceleration). Δt indicates the offset time at the time of resetting, and c indicates the speed of light.

  Conventionally, in the compensation for the reset of the clock of the GPS receiver 200, the following equation 2 is calculated.

  As shown in Equation 2 above, conventionally, compensation for clock reset has been performed by adding a distance (c × Δt) for the offset to the value of the clock bias.

Compared with the conventional formula 2, the above formula 1 adds a displacement distance (Δt × tcd, k) due to clock drift within the offset time to the calculation of the clock bias (tcb, k). Thus, for example, when the offset is 1 msec by resetting the clock, if the clock drift is 300 m / s, an error of about 3 m can be corrected with respect to the conventional equation 2, and the offset time or If the clock drift value is large, the error can be further corrected. That is, positioning accuracy can be improved.
Further, in the above formula 1, the calculation for the clock bias acceleration (tca, k) is added as compared with the conventional formula 2. As a result, the positioning accuracy can be increased as described above.
In the calculation for compensation for the clock reset, the addition of the displacement distance (Δt × tcd, k) due to the clock drift and the calculation for the clock bias acceleration (tca, k) are respectively described in the embodiments. 1 is a characteristic point of the positioning device 100 and the arithmetic unit 300.

  The reset detection / compensation unit 360 outputs a clock error to the residual calculation unit 350 after the above processing.

  Next, the positioning calculation unit 370 inputs the distance residual, the distance change rate residual, and the clock error from the residual calculation unit 350, performs Kalman filter processing, performs positioning calculation on the moving body, and moves the moving body position. , Mobile speed, clock error is output.

FIG. 5 is a configuration diagram of the positioning calculation unit 370 in the first embodiment.
The Kalman filter process of the positioning calculation unit 370 will be described below with reference to FIG.

  Hereinafter, the superscript “+” used in the equations indicates an estimated value after Kalman processing, and the superscript “−” indicates a predicted value before Kalman processing. The superscript “T” indicates a transposed matrix, and the superscript “−1” indicates an inverse matrix. The subscript “k” indicates the time of observation. Here, “k” corresponds to the previous observation, and “k + 1” corresponds to the current observation after one sampling time has elapsed from “k”.

  The positioning calculation unit 370 includes a time extrapolation processing unit 371 and an observation update processing unit 372.

  First, the time extrapolation processing unit 371 applies the transition matrix Φ indicating the transition of the state quantity to the state quantity X (moving body position, moving body speed, clock error) of the moving body that has been subjected to the Kalman filter processing, for one sampling time. Extrapolation is performed to obtain a predicted value of the state quantity X. The calculation formula is shown in Formula 3.

  Next, the time extrapolation processing unit 371 performs extrapolation on the error covariance matrix P to obtain a predicted value of the error covariance matrix P. The calculation formula is shown in Formula 4.

  In the above equation 4, Q represents a process noise matrix, which is calculated corresponding to the dynamics of the moving object.

  Next, the observation update processing unit 372 obtains a Kalman gain matrix K. The calculation formula is shown in Formula 5.

  In Equation 5, H represents an observation matrix, and is calculated by obtaining a direction cosine vector from the geometric relationship between the satellite and the moving body. R represents an observation noise matrix, which is calculated corresponding to a reception state of the GPS receiver 200 such as a C / N (Carrier / Noise) ratio and an elevation angle.

  Next, the observation update processing unit 372 updates the prediction value of the error covariance matrix P obtained by the time extrapolation processing unit 371 by using the Kalman gain matrix K obtained by Expression 5, and the error covariance matrix P Obtain an estimate of. The calculation formula is shown in Formula 6.

  Next, the observation update processing unit 372 updates the predicted value of the state quantity X obtained by the time extrapolation processing unit 371 using the Kalman gain matrix K obtained by Equation 5, and obtains the estimated value of the state quantity X. Ask. The calculation formula is shown in Formula 7.

  In Equation (7), Z represents an observed quantity vector, and is an observed quantity (moving object position, moving object speed, clock error) of the moving object that includes the residual calculated by the residual calculating unit 350 as a clock error.

  The positioning calculation unit 370 performs the above processing and outputs the obtained state quantity X (moving body position, moving body speed, clock error). Then, the output moving body position becomes the positioning result of the positioning device 100. The output mobile body position, mobile body speed, and clock error are input to the arithmetic unit 300 during the next positioning calculation process.

  Further, the estimated value of the state quantity X and the estimated value of the error covariance matrix P obtained by the observation update processing unit 372 of the positioning calculation unit 370 are the same as those in the next state quantity extrapolation process (Equation 3) and the error covariance extrapolation. It becomes an input of the time extrapolation processing unit 371 at the time of processing (Equation 4).

Next, feature points in the first embodiment at the time of Kalman filter processing performed by the positioning calculation unit 370 will be described.
FIG. 6 is a diagram illustrating a conventional clock error model.
The clock error model of FIG. 6 is the matrix element of the transition matrix Φ used by the time extrapolation processing unit 371 of the positioning calculation unit 370 in the state quantity extrapolation processing (Equation 3) and the error covariance extrapolation (Equation 4). The conventional model about the part which shows transition of a clock error is shown. A formula representing this conventional clock error model is shown in Formula 8.

In the above equation 8, T _S indicates a sampling interval and is an elapsed time since the previous positioning calculation. Wcb, k and Wcd, k are white noises with respect to the clock bias and the clock drift, respectively, and this white noise has an average value of zero and known dispersion. In the relationship with the clock error model in FIG. 6, Wcb, k and Wcd, k are obtained by replacing Wb and Wd with discrete systems, respectively.

  Here, when the XO without temperature compensation is used for the crystal clock instead of the TCXO with temperature compensation as in the first embodiment, there is a problem that the clock bias acceleration increases due to poor clock accuracy. . However, the conventional clock error model shown above is a two-dimensional model composed of a clock bias and a clock drift, and there is a problem that positioning accuracy is deteriorated because the influence of clock bias acceleration cannot be removed.

FIG. 7 is a graph showing the clock bias in the first embodiment.
FIG. 8 is a graph showing clock drift in the first embodiment.
When the XO without temperature compensation is used as in the first embodiment, the clock bias changes as shown in FIG. FIG. 8 shows a change in clock drift indicating a clock speed obtained by differentiating the clock bias. It can be seen that the value of the clock acceleration obtained by differentiating the clock drift is large because the value changes greatly.

Therefore, in the first embodiment, a clock error model for removing the influence of clock bias acceleration is used.
FIG. 9 is a diagram illustrating a clock error model according to the first embodiment. Expression 9 represents the clock error model in the first embodiment expressed by a mathematical expression.

In the clock error model in the first embodiment, the clock bias acceleration tca, k is added to the conventional clock error model. In other words, the clock bias tcb, the value of the distance calculated from the acceleration in the k (tca, k) × ( Ts 2/2) was added, clock drift tcd, the rate of the value calculated from the acceleration in the k (tca, k) X Ts is added.

FIG. 10 is a graph showing clock bias acceleration in the first embodiment.
It can be seen that the change in the clock bias acceleration in FIG. 10 is less than the change in the clock drift in FIG. For this reason, by removing the influence of the clock bias acceleration, it can be said that positioning can be performed with high accuracy even when XO without temperature compensation is used.

  As described above, the feature of the first embodiment is that the clock error model is a three-dimensional model of clock bias, clock drift, and clock bias acceleration.

  In the first embodiment, in the positioning device 100 that calculates the position / velocity of the moving object based on the signal from the GPS satellite, the function of estimating the change rate of the drift error of the mounted clock and the function of eliminating the discontinuity at the time of clock reset It was shown that the addition of was the point.

In other words, in the conventional positioning calculation unit, the clock error model is a secondary system consisting of a clock bias and a clock drift rate, but in order to obtain high accuracy even with a low-cost clock with low stability, the clock bias acceleration is set. One of the points is to construct the Kalman filter dynamics as an added third order system and perform estimation.
In the second-order model, it is assumed that the clock bias acceleration is Gaussian noise. However, when an inexpensive temperature uncompensated clock (XO) is used, a clock bias acceleration having a correlation component is generated, and this assumption holds. Absent. For this reason, the estimation accuracy by the Kalman filter is lowered, and the error is enlarged. Therefore, in the first embodiment, the error is prevented from being enlarged by modeling the clock bias acceleration as a bias component (random walk process) that fluctuates.

Thereby, the accuracy of the position / velocity estimated by the Kalman filter is improved, and the accuracy of the Doppler integration can be improved by improving the velocity estimation accuracy, thereby improving the reception sensitivity. Furthermore, by estimating the dynamic model of the clock with high accuracy, position / velocity estimation accuracy in the case of satellite tracking interruption is improved.
Here, a description will be given of improvement in reception sensitivity. Although the GPS signal is very weak, a C / A code with a period of 1 msec is transmitted 20 times continuously, and integration can be performed between samples of a navigation message of 50 Hz. Further, the sensitivity can be further increased by performing integration at a period of 20 msec or longer after the signal is squared. However, since the Doppler transition between the satellite and the GPS receiver changes during this integration, it is necessary to perform integration while performing correction. In order to perform this correction, the Doppler transition amount is integrated, and this is called Doppler integration. In order to perform this correction with high accuracy, it is necessary to accurately estimate the Doppler transition amount, and it is necessary to improve the estimation accuracy of the speed of the moving body. In other words, the reason is that the reception sensitivity is improved by the first embodiment.
Next, a description will be given of the improvement in position / velocity estimation accuracy when satellite tracking is cut off. In the case of satellite tracking interruption, the position is obtained by extrapolating the speed, but the influence of the clock bias acceleration on the speed cannot be removed by the conventional method, but can be removed by the first embodiment. It is relatively good and the accuracy of the extrapolated position is improved.

The reset detection / compensation unit 360 adds a displacement distance (Δt × tcd, k) due to the clock drift and calculates the clock bias acceleration (tca, k) to calculate the clock bias and clock drift that compensate for the clock reset. The point is to add minutes.
In the GPS receiver 200, in order to keep the clock bias error at a small value, reset processing is performed when the error exceeds a certain threshold. At this time, in the Kalman filter that assumes continuous dynamics, if the discontinuity due to the reset is not detected and compensated, the influence of the discontinuity or the like occurs on the position / speed estimation output of the moving body. In addition, when using a low-cost clock (XO) having a correlation component in the clock bias acceleration, discontinuity occurs due to the influence of the clock bias acceleration at the time of reset. Therefore, in the first embodiment, the occurrence of the discontinuity is prevented by performing correction in consideration of the influence of the clock bias acceleration.

1 is a configuration diagram of a positioning device 100 according to Embodiment 1. FIG. FIG. 2 is a hardware configuration diagram of the positioning device 100, the GPS receiver 200, and the arithmetic unit 300 in the first embodiment. FIG. 2 is a configuration diagram of a GPS receiver 200 in the first embodiment. FIG. 3 is a configuration diagram of a calculator 300 in the first embodiment. FIG. 3 is a configuration diagram of a positioning calculation unit 370 in the first embodiment. The figure which shows the conventional clock error model. 3 is a graph showing a clock bias in the first embodiment. 3 is a graph showing clock drift in the first embodiment. FIG. 4 shows a clock error model in the first embodiment. 3 is a graph showing clock bias acceleration in the first embodiment.

Explanation of symbols

  100 positioning device, 200 GPS receiver, 210 GPS antenna, 220 RF front end processing unit, 230 XO, 240 A / D conversion unit, 250 baseband chip processing unit, 300 arithmetic unit, 310 distance correction calculation unit, 320 satellite position / Speed calculation unit, 330 observation amount correction unit, 340 relative motion calculation unit, 350 residual calculation unit, 360 reset detection / compensation unit, 370 positioning calculation unit, 371 time extrapolation processing unit, 372 observation update processing unit, 911 CPU , 912 bus, 913 ROM, 914 RAM, 915 communication board, 920 magnetic disk device, 921 OS, 923 program group, 924 file group.

Claims (9)

In the positioning calculator that inputs the output data of the receiver that receives the positioning signal, which is a receiver equipped with a clock, and performs the positioning calculation on the positioning object using the Kalman filter corresponding to the error of the clock provided in the receiver.
The clock error of the receiver is the clock bias indicating the position error of the positioning target based on the clock error, the clock drift indicating the speed error of the positioning target based on the clock error, and the positioning target acceleration based on the clock error. A positioning calculator that performs a positioning operation on a positioning target by performing a Kalman filter process with a clock bias acceleration indicating an error in the positioning. This is a positioning calculator that performs positioning calculation on the positioning target by inputting the output data of the receiver that receives the positioning signal, and is equipped with a clock. In a positioning calculator that performs positioning calculations on positioning targets in response to errors,
When the receiver resets the clock, a value corresponding to the distance corresponding to the clock drift indicating the speed error of the positioning target based on the clock error is added to the clock bias indicating the positioning position error based on the clock error. A positioning calculator that performs a positioning calculation on a positioning target by adding.   When the receiver resets the clock, the value corresponding to the distance corresponding to the clock bias acceleration indicating the error of the positioning target acceleration based on the clock error and the clock bias indicating the positioning target position error based on the clock error The positioning calculator according to claim 2, wherein the positioning calculation is performed on the positioning target. An antenna for receiving a positioning signal including a navigation message from a satellite and a clock for generating a reference signal are provided, and a satellite and a positioning target based on a phase difference between the positioning signal received from the antenna and a reference signal generated by the clock. Information on the frequency difference between the received positioning signal and the positioning signal transmitted by the satellite is calculated as the Doppler amount, the navigation message included in the received positioning signal, the calculated distance, and the calculated Doppler amount A receiver that outputs
A positioning calculator that calculates and outputs the position of the positioning target and the speed of the positioning target.
A satellite position / velocity calculation unit that inputs a navigation message output by a receiver, calculates a satellite position and a satellite velocity based on the input navigation message, and outputs the calculated position;
The positioning target position output by the positioning calculator, the satellite position output by the satellite position / velocity calculation unit, and the navigation message output by the receiver are input, and the input positioning target position, the satellite position and the navigation message are input. And calculating the correction amount for the distance output by the receiver, and the relative velocity in the distance direction between the satellite and the positioning target based on the Doppler amount output by the receiver as the distance change rate and the position of the input positioning target. A distance correction calculation unit that calculates a correction amount for the distance change rate based on the position of the satellite and the navigation message, and outputs a correction amount for the calculated distance and a correction amount for the distance change rate;
The distance output by the receiver and the Doppler amount are input as observation amounts, and the correction amount for the distance output by the distance correction calculation unit and the correction amount for the distance change rate are input, and the correction for the input distance is input to the input distance. In addition to adding the amount, the relative speed in the distance direction between the satellite and the positioning target based on the input Doppler amount is used as the distance change rate, and the correction amount for the input distance change rate is added to the distance change rate, and the correction amount is added. An observation amount correction unit that outputs a distance and a rate of change in distance;
Input the position of the positioning target output by the positioning calculator, the speed of the positioning target, the position of the satellite and the speed of the satellite output by the satellite position / velocity calculation unit, the distance between the satellite and the positioning target, the satellite and the positioning target A relative motion calculation unit that calculates and outputs a distance change rate indicating a relative speed in the distance direction of
Enter the distance and distance change rate output by the observation amount correction unit, the distance and distance change rate output by the relative motion calculation unit, and the difference between the distance input from the observation amount correction unit and the distance input from the relative motion calculation unit And a residual calculation unit that calculates a difference between the distance change rate input from the observation amount correction unit and the distance change rate input from the relative motion calculation unit and outputs as a residual,
The residual output from the residual calculator is input, and the clock error of the receiver is calculated as the clock bias indicating the position error based on the clock error and the speed error based on the clock error. The clock drift acceleration and the clock bias acceleration indicating the error of the positioning target acceleration based on the clock error are shown. Based on the input residual, the clock error is processed as the clock bias, clock drift and clock bias acceleration. A positioning apparatus comprising: a positioning calculation unit that performs a positioning calculation on a positioning target and outputs a position of the positioning target calculated by the positioning calculation and a speed of the positioning target. An antenna for receiving a positioning signal including a navigation message from a satellite having a clock and a clock for generating a reference signal, and a satellite based on a phase difference between the positioning signal received from the antenna and a reference signal generated by the clock And the distance between the positioning target and the information on the frequency difference between the received positioning signal and the positioning signal transmitted by the satellite is calculated as the Doppler amount, and the navigation message included in the received positioning signal and the calculated distance are calculated. A receiver that outputs the amount of Doppler, a receiver that resets the clock when the clock of the receiver and the clock of the satellite cannot be synchronized, and
It is a positioning calculator that calculates and outputs the position of the positioning target, the speed of the positioning target, and the clock error of the receiver,
A satellite position / velocity calculation unit that inputs a navigation message output by a receiver, calculates a satellite position and a satellite velocity based on the input navigation message, and outputs the calculated position;
The positioning target position output by the positioning calculator, the satellite position output by the satellite position / velocity calculation unit, and the navigation message output by the receiver are input, and the input positioning target position, the satellite position and the navigation message are input. And calculating the correction amount for the distance output by the receiver, and the relative velocity in the distance direction between the satellite and the positioning target based on the Doppler amount output by the receiver as the distance change rate and the position of the input positioning target. A distance correction calculation unit that calculates a correction amount for the distance change rate based on the position of the satellite and the navigation message, and outputs a correction amount for the calculated distance and a correction amount for the distance change rate;
The distance output by the receiver and the Doppler amount are input as observation amounts, and the correction amount for the distance output by the distance correction calculation unit and the correction amount for the distance change rate are input, and the correction for the input distance is input to the input distance. In addition to adding the amount, the relative speed in the distance direction between the satellite and the positioning target based on the input Doppler amount is used as the distance change rate, and the correction amount for the input distance change rate is added to the distance change rate, and the correction amount is added. An observation amount correction unit that outputs a distance and a rate of change in distance;
Input the position of the positioning target output by the positioning calculator, the speed of the positioning target, the position of the satellite and the speed of the satellite output by the satellite position / velocity calculation unit, the distance between the satellite and the positioning target, the satellite and the positioning target A relative motion calculation unit that calculates and outputs a distance change rate indicating a relative speed in the distance direction of
Enter the distance and distance change rate output by the observation amount correction unit, the distance and distance change rate output by the relative motion calculation unit, and the difference between the distance input from the observation amount correction unit and the distance input from the relative motion calculation unit And a residual calculation unit that calculates a difference between the distance change rate input from the observation amount correction unit and the distance change rate input from the relative motion calculation unit and outputs as a residual,
When the clock error output by the positioning calculator is input and the receiver resets the clock, the clock bias indicating the positioning target position error based on the clock error is set to the positioning target speed based on the clock error. A reset calculation unit that calculates and outputs a value corresponding to a distance corresponding to a clock drift indicating an error; and
The residual output from the residual calculation unit and the clock bias output from the reset calculation unit are input, and the positioning calculation is performed on the positioning target based on the input residual and clock bias, and the positioning target position and the positioning target A positioning apparatus comprising a positioning calculation unit that outputs a speed and a clock error. The reset calculator is
When the receiver resets the clock, the value corresponding to the distance corresponding to the clock bias acceleration indicating the error of the positioning target acceleration based on the clock error and the clock bias indicating the positioning target position error based on the clock error 6. The positioning device according to claim 5, wherein a calculation for adding is performed and output. A positioning calculation method for a positioning calculator that inputs output data of a receiver that is equipped with a clock and receives a positioning signal, and performs positioning calculation for a positioning target using a Kalman filter in response to an error of the clock included in the receiver. In
The clock error of the receiver is the clock bias indicating the position error of the positioning target based on the clock error, the clock drift indicating the speed error of the positioning target based on the clock error, and the positioning target acceleration based on the clock error. A positioning calculation method characterized in that a positioning calculation is performed on a positioning target by performing a Kalman filter processing expressed by a clock bias acceleration indicating an error of the positioning error. This is a positioning calculator that performs positioning calculation on the positioning target by inputting the output data of the receiver that receives the positioning signal, and is equipped with a clock. In the positioning calculation method of the positioning calculator that performs the positioning calculation for the positioning target in response to the error,
When the receiver resets the clock, a value corresponding to the distance corresponding to the clock drift indicating the speed error of the positioning target based on the clock error is added to the clock bias indicating the positioning position error based on the clock error. A positioning calculation method characterized by adding and performing a positioning calculation on a positioning target.   When the receiver resets the clock, the value corresponding to the distance corresponding to the clock bias acceleration indicating the error of the positioning target acceleration based on the clock error and the clock bias indicating the positioning target position error based on the clock error The positioning calculation method according to claim 8, wherein the positioning calculation is performed on the positioning target by adding.

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