JP2019078596A - Flight vehicle-purpose navigation device and flight vehicle control method - Google Patents

Abstract

To provide a flight vehicle-purpose navigation device and flight vehicle control method that can derive a location and speed of a flight vehicle with high accuracy.SOLUTION: A flight vehicle-purpose navigation device comprises: one or more antennas that receive a radio wave from each of a plurality of five or more man-made satellites; a first derivation unit that derives a relative distance and relative speed between the man-made satellite and a flight vehicle at a time when the radio wave is received as an index value as to each of the plurality of man-made satellites on the basis of the radio wave received by each antenna; a prediction unit that predicts at least one index value of the relative distance and relative speed between the man-made satellite and the flight vehicle at a time in future as to each of the plurality of man-made satellites; and a second derivation unit that derives a location and speed of the flight vehicle on the basis of a comparison result of the index value derived by the first derivation unit based on the radio wave received by the antenna at the prediction time of the prediction unit with the prediction value predicted by the prediction unit.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an aircraft navigation system and an aircraft control method.

  In recent years, techniques such as measuring the position and velocity of a flight vehicle are known by mounting an inertial sensor and a positioning sensor by a positioning satellite on a flight vehicle such as a rocket and using detection results of these sensors in combination. (See Patent Documents 1 and 2).

US Patent No. 8868258 U.S. Pat. No. 5,737,978

  However, in satellite positioning, the relative distance between the satellite and the aircraft (hereinafter referred to as pseudo range) and the relative velocity between the satellite and the aircraft (hereinafter referred to as pseudo) based on radio waves transmitted by the satellite In the case where the propagation path of the radio wave from the artificial satellite can not be viewed linearly from the determination of the range rate), an error may occur in the satellite positioning due to the multipath propagation. As a result, the measurement accuracy of the position and velocity of the flying object may be reduced.

  The present invention has been made in consideration of such circumstances, and it is an object of the present invention to provide an aircraft navigation system and an aircraft control method capable of accurately deriving the position and velocity of an aircraft. To be

  One aspect of the present invention is a flight navigation system mounted on a flight vehicle, wherein each of the one or more antennas receives radio waves from each of a plurality of five or more artificial satellites, and each of the one or more antennas. A first derivation unit for deriving, as an index value, a relative distance and a relative velocity between the artificial satellite and the aircraft at the time of reception of the radio wave for each of the plurality of artificial satellites based on the radio wave received by A prediction unit for predicting an index value of at least one of a relative distance and a relative velocity between the satellite and the aircraft at a certain time in the future for each of the plurality of satellites; a prediction time of the prediction unit Based on the comparison result between the index value derived by the first derivation unit based on the radio wave received by the antenna and the index value predicted by the prediction unit. Te, a second deriving unit that derives the position and speed of the aircraft, a flight-body navigation device comprising a.

  According to one aspect of the present invention, the position and velocity of the flying object can be derived accurately.

It is a figure which shows an example of the use scene of the rocket 1 by which the flight navigation device 100 of 1st Embodiment was mounted. It is a schematic block diagram of the rocket 1 of 1st Embodiment. It is a block diagram of the flight navigation system 100 of 1st Embodiment. It is a figure which shows an example of a structure of the arithmetic module 110 of 1st Embodiment. It is a flow chart which shows an example of a series of processings by operation module 110 of a 1st embodiment. It is a figure which shows an example of a simulation result. It is a figure for demonstrating the method to determine the presence or absence of the multi-path by aircraft dynamics. It is a figure for demonstrating the method to determine the presence or absence of the multi-path by aircraft dynamics.

  Hereinafter, with reference to the drawings, embodiments of a flight navigation system and a flight control method of the present invention will be described. The flight navigation system is a device mounted on a flight vehicle such as a rocket, an artificial satellite, a spacecraft, an aircraft, a flight drone, and the like. In the following, the aircraft is described as a rocket as an example, but as described above, it may be another aircraft such as an artificial satellite or a spacecraft. In addition to the flight vehicle, the flight navigation system may be mounted on another mobile vehicle such as a car or a ship.

First Embodiment
[Use scene]
FIG. 1 is a view showing an example of a usage scene of the rocket 1 on which the aircraft navigation device 100 of the first embodiment is mounted. For example, the rocket 1 is launched upward from the launch site (fire point) where the lightning arrester LT or the like is built. At this time, the flight navigation system 100 mounted on the rocket 1 derives the position and velocity of the rocket 1 based on each radio wave transmitted by each of the five or more artificial satellites (navigation satellites) SAT. The rocket 1 is navigated to the destination based on the position and velocity. The satellite SAT may include a quasi-zenith satellite. In the present embodiment, as an example, the flight navigation system 100 will be described as capturing eight satellites SAT.

Rocket Configuration
FIG. 2 is a schematic block diagram of the rocket 1 of the first embodiment. The rocket 1 is, for example, a multistage rocket, and an artificial satellite or the like is stored in the uppermost stage, and the lower stages are separated from the uppermost stage during navigation and fall. The rocket 1 includes, for example, a first stage rocket 10, a second stage rocket 12, and a top stage third stage rocket 14. Immediately after the rocket 1 is launched, the rocket 1 flies with the propulsive force by the first stage rocket 10, and then, after separating the first stage rocket 10, it flies with the propulsive force of the second stage rocket 12 and finally the third stage rocket 14 causes a payload 20 such as a satellite to reach space. The aircraft navigation system 100 is stored, for example, in the second stage rocket 12.

[Aircraft navigation system]
The flight navigation system 100 derives the pseudo ranges and pseudo range rates between each of the eight satellites SAT and the rocket 1, and derives the total of 8 derived pseudo ranges and pseudo range rates, and the rockets. The position and velocity of the rocket 1 are derived by combining the position and velocity determined based on the inertial force of 1. At this time, the flight navigation system 100 determines whether the pseudo range and the pseudo range rate corresponding to each satellite SAT include an error due to the influence of the multipath, and the error due to the multipath is included. If it is determined, the position and velocity of the rocket 1 are derived using the remaining pseudo range and pseudo range rate without errors, without utilizing the pseudo range and pseudo range rate including errors.

  FIG. 3 is a block diagram of the flight navigation system 100 of the first embodiment. The flight navigation device 100 is connected to, for example, one or more antennas AT and a communication device TM. The flight vehicle navigation device 100 includes, for example, an arithmetic module 110, an IMU (Inertial Measurement Unit; inertial measurement device) 130, a power supply module 140, and a storage unit 150. In the present embodiment, for example, it is assumed that three or more antennas AT are provided in the flight navigation system 100.

  The antenna AT receives radio waves from the outside (for example, radio waves from the satellite SAT), and outputs a signal (hereinafter referred to as a satellite positioning signal) corresponding to the received radio waves to an LNA (Low Noise Amplifier). The LNA amplifies the satellite positioning signal input from the antenna AT, and outputs the satellite positioning signal to the arithmetic module 110.

  The calculation module 110 derives the position and velocity of the rocket 1 based on the satellite positioning signal input from the LNA and the information input from the IMU 130.

  The IMU 130 includes, for example, a triaxial acceleration sensor composed of MEMS (Micro Electro Mechanical Systems) and an optical fiber, and a triaxial gyro sensor. The IMU 130 outputs the values detected by these sensors to the arithmetic module 110. The detected values by the IMU 130 include, for example, accelerations in the horizontal direction, the vertical direction, and the depth direction, and the speeds (rates) of the pitch, roll, and yaw axes.

  The power supply module 140 is connected to a power supply not shown. The power supply module 140 includes, for example, a protection circuit and a DC-DC converter, and supplies power to each part of the aircraft navigation device 100.

  The storage unit 150 is realized by, for example, a read only memory (ROM), a random access memory (RAM), and an electrically erasable programmable read only memory (EEPROM). In addition, the storage unit 150 may be realized by an HDD (Hard Disc Drive), a flash memory, or the like. The storage unit 150 stores, for example, various processing results by the arithmetic module 110.

  The communication device TM transmits various information to a ground monitoring device (not shown) using, for example, a telemeter line. The ground monitoring device acquires, for example, the position and velocity of the rocket 1 after the rocket 1 has been launched from the rocket 1 by telemetry communication. Then, the ground monitoring device repeatedly estimates the dropping point when the rocket 1 falls temporarily, and transmits an instruction signal to the rocket 1 so as to avoid the danger due to the falling. When the ground monitoring device can not acquire information on the position and velocity from the rocket 1 even after a predetermined time has elapsed, the ground monitoring device transmits a command signal for restarting the flight navigation device 100 mounted on the rocket 1. Do.

  FIG. 4 is a diagram showing an example of the configuration of the arithmetic module 110 according to the first embodiment. For example, the arithmetic module 110 includes an inertial navigation arithmetic processing unit 112, a satellite navigation arithmetic processing unit 114, a combined navigation arithmetic processing unit 116, a prediction unit 118, and a determination unit 120. The satellite navigation arithmetic processing unit 114 is an example of the “first derivation unit”, and the combined navigation arithmetic processing unit 116 is an example of the “second derivation unit”. The combination of the IMU 130 and the inertial navigation arithmetic processing unit 112 is an example of the “detection unit”.

  Part or all of the components of the calculation module 110 are realized by execution of a program stored in the storage unit 150 by a processor such as a micro processing unit (MPU) or a central processing unit (CPU). Also, some or all of the components of the computing module 110 may be realized by hardware such as a field-programmable gate array (FPGA), a large scale integration (LSI), or an application specific integrated circuit (ASIC). , May be realized by cooperation of software and hardware.

  The inertial navigation arithmetic processing unit 112 derives the position of the rocket 1 based on the detection value input from the IMU 130. For example, the inertial navigation processing unit 112 derives the position of the rocket 1 by time-integrating the velocity included in the detection value. In addition, the inertial navigation arithmetic processing unit 112 may derive the velocity by temporally integrating the acceleration included in the detected value, and may further derive the position of the rocket 1 by temporally integrating the velocity. The inertial navigation processing unit 112 outputs the information indicating the derived velocity and / or position to the composite navigation processing unit 116 and the prediction unit 118.

  The satellite navigation processing unit 114 derives a pseudo range and a pseudo range rate for each of the satellites SAT based on satellite positioning signals corresponding to the radio waves of eight satellites SAT, for example. For example, the satellite navigation processing unit 114 determines the propagation speed (speed of light) of the radio wave as the difference between the transmission time when the radio wave is transmitted by each satellite SAT and the reception time when the radio wave is received from the satellite SAT. The pseudo range of each satellite SAT is derived by multiplying. The satellite navigation processing unit 114 also derives a Doppler frequency from the Doppler shift of the frequency of each satellite positioning signal, and derives a pseudorange rate of each artificial satellite SAT based on the Doppler frequency. In addition, the satellite navigation processing unit 114 may derive a pseudo range rate from time change of the pseudo range instead of using the Doppler frequency.

  Then, the satellite navigation processing unit 114 derives the position and velocity of the rocket 1 based on the derived pseudo range and the pseudo range rate (hereinafter also referred to as an observation value). For example, the satellite navigation processing unit 114 determines the position of each artificial satellite SAT from the navigation message (ephemeris) included in the radio waves of each artificial satellite SAT, and determines the position of the artificial satellite SAT and each artificial satellite SAT. Based on the pseudo range, the intersection point positions of the circles equidistant from each artificial satellite SAT are derived. Further, the satellite navigation arithmetic processing unit 114 obtains an error of the reception time of the radio wave from each of the artificial satellites SAT, and corrects the intersection point position of the circle equidistant from each of the artificial satellites SAT. The satellite navigation processing unit 114 derives, as the position of the rocket 1, the point of intersection of circles equidistant from each of the satellites SAT. At this time, the satellite navigation arithmetic processing unit 114 uses the radio waves of five or more satellites SAT to solve four unknowns of the three-dimensional position of each dimension and the error of the reception time of the radio waves. Of the rocket 1 by solving four unknowns so that the sum of squares of the distance error components is minimized, assuming that the pseudo range of each artificial satellite SAT contains the distance error components. Derive the position.

  Also, for example, the satellite navigation processing unit 114 determines the speed of each satellite SAT from the navigation message (ephemeris) included in the radio waves of each satellite SAT, and the speed of each satellite SAT and each satellite SAT. And the pseudo range rate, which is the relative speed of the rocket 1, to derive the speed of the rocket 1. The satellite navigation processing unit 114 outputs information indicating the derived position and velocity to the composite navigation processing unit 116 and the prediction unit 118. In the following, deriving the position and velocity of the rocket 1 based on the observed values of the pseudo range and the pseudo range rate will be described as “satellite positioning”.

  The combined navigation processing unit 116 combines the position and velocity of the rocket 1 derived by the inertial navigation processing unit 112 and the position and velocity of the rocket 1 derived by the satellite navigation processing unit 114 into an integrated form. To derive. Hereinafter, the process of integrating the position and velocity will be described as "combined navigation".

  For example, the composite navigation processing unit 116 calculates the difference between the position of the rocket 1 derived by the inertial navigation processing unit 112 and the position of the rocket 1 derived by the satellite navigation processing unit 114, and the inertial navigation processing unit The difference between the velocity of the rocket 1 derived by 112 and the velocity of the rocket 1 derived by the satellite navigation processing unit 114 is determined, and the position and velocity of the future rocket 1 are calculated from these differences using a time series filter Predict. The time series filter is, for example, an algorithm for predicting the future state of an observation target (in the embodiment, rocket 1) such as a Kalman filter. The combined navigation processing unit 116 corrects the position and velocity of the rocket 1 derived by the satellite navigation processing unit 114 based on the predicted position and velocity of the rocket 1 in the future. “Correction” is, for example, averaging the predicted values of position and velocity and observed values of position and velocity by arithmetic mean, geometric average, or the like. Thereby, the position and velocity of the rocket 1 derived by each arithmetic processing unit are integrated. The combined navigation processing unit 116 then transmits the integrated information on the position and velocity of the rocket 1 to the ground monitoring device using the communication device TM.

  The prediction unit 118 predicts one or both of a pseudo range and a pseudo range rate (hereinafter, one or both of them is also referred to as a predicted value) at a certain time in the future, for each of eight satellites SAT. For example, the prediction unit 118 may determine the position of an unknown number of rockets 1 that may be obtained from the pseudo range assumed to be observed in the future and the pseudo range rate that is also assumed to be observed in the future. It is assumed that each of the velocity of the rocket 1 and the velocity and velocity of the rocket 1 is the position and velocity of the rocket 1 derived by the inertial navigation processing unit 112. The pseudo range and the pseudo range rate at a certain point in the future are predicted by back-calculating the pseudo range and the pseudo range rate that should be known at a certain point in the future.

  In addition, the prediction unit 118 calculates a pseudo range and a pseudo range rate at a certain time in the future for each of the eight satellites SAT based on the position and velocity of the rocket 1 derived in the past by the satellite navigation processing unit 114. One or both may be predicted. For example, the prediction unit 118 obtains the acceleration of the rocket 1 by temporally differentiating the amount of change in the velocity of the rocket 1 derived by the satellite positioning of the satellite navigation processing unit 114 in the previous and previous two times. More specifically, when the satellite navigation processing unit 114 repeatedly derives the velocity of the rocket 1 in a 10 [Hz] cycle by satellite positioning, the prediction unit 118 determines that the amount of change in velocity is 0.1 [s]. Find the acceleration by differentiating with. Then, the prediction unit 118 predicts the velocity and position derived by satellite positioning in the next cycle from the obtained acceleration and velocity.

  The determination unit 120 determines, based on the pseudo range and the pseudo range rate predicted by the prediction unit 118, whether or not multipath has occurred. Then, the satellite navigation arithmetic processing unit 114 described above changes the method of deriving the position and velocity of the rocket 1 according to the determination result of the determination unit 120. Details of this process will be described later using a flowchart.

  FIG. 5 is a flowchart showing an example of a series of processing by the operation module 110 according to the first embodiment. The processing of this flowchart is repeatedly performed, for example, at a predetermined cycle (for example, 100 [Hz] cycle) after the rocket 1 is launched.

  First, the prediction unit 118 predicts one or both of a pseudo range and a pseudo range rate at a certain time in the future, for each of the eight satellites SAT (step S100).

  Next, the determination unit 120 clears the temporary parameter N to zero (step S102). The temporary parameter N is an internal parameter used for the processing operation of this flowchart, and corresponds to the number of satellites SAT to be supplemented. In the subsequent processing, it is assumed that the temporary parameter N indicates the satellite SAT (N) to be processed. The artificial satellite SAT (N) to be processed is an example of a "target artificial satellite".

  Next, the determination unit 120 increments the temporary parameter N that has been cleared to zero so that N = N + 1 (step S104). For example, in the first process, the satellite SAT (1) is selected as a processing target among eight satellites SAT.

  Next, determination unit 120 selects a pseudo range derived based on a satellite positioning signal of antenna AT satisfying a predetermined condition among a plurality of antennas AT that have received radio waves of artificial satellite SAT (N) selected as a processing target and The pseudo range rate is acquired from the satellite navigation processing unit 114 (step S106). The predetermined condition is, for example, that the reception power (signal strength of the satellite positioning signal) is the largest.

  Next, the determination unit 120 compares the pseudo range and the pseudo range rate acquired from the satellite navigation processing unit 114 with the pseudo range and the pseudo range rate predicted by the prediction unit 118 (step S108). For example, when the satellite SAT targeted for processing of the pseudo range and the pseudo range rate acquired from the satellite navigation processing unit 114 is SAT (1), the determination unit 120 predicts each of the eight satellites SAT. Among the plurality of pseudo ranges and pseudo range rates predicted by unit 118, the pseudo range and pseudo range rate predicted when the satellite SAT (1) is to be processed is selected, and the selected pseudo range and pseudo range are selected. The range rate (predicted value) is compared with the pseudo range and pseudo range rate (observed value) obtained from the satellite navigation processing unit 114. When only one of the pseudo range and the pseudo range rate is predicted by the prediction unit 118, the determination unit 120 may compare only the pseudo ranges or only the pseudo range rates.

  Next, the determination unit 120 determines whether or not a multipath is generated based on the difference between the compared pseudoranges and / or the difference between the pseudo range rates (step S110). For example, when the difference between the pseudo ranges and / or the difference between the pseudo range rates is equal to or greater than the threshold, the determination unit 120 determines that multipath is generated in the radio wave received by the antenna AT that satisfies the predetermined condition. For example, when the pseudo range rate which is a predicted value is 5 [m / s] and the pseudo range rate which is an observed value is 10 [m / s], for example, the determination unit 120 has an obvious error. , It is determined that multi-path has occurred.

  On the other hand, when the difference between the pseudo ranges and / or the difference between the pseudo range rates is less than the threshold, the determination unit 120 determines that multipath does not occur in the radio wave received by the antenna AT that satisfies the predetermined condition.

  If it is determined that the multipath does not occur in the received radio wave of the antenna AT satisfying the predetermined condition, the satellite navigation operation processing is performed based on the received radio wave of the antenna A in the current processing cycle of the flowchart. The pseudo range and the pseudo range rate derived by the unit 114 are permitted to be used for satellite positioning by the satellite navigation processing unit 114 (step S112).

  On the other hand, when determining section 120 determines that a multipath is generated in the received radio wave of the antenna AT satisfying the predetermined condition, the predetermined condition is satisfied among the other antennas AT excluding the antenna AT satisfying the predetermined condition. The pseudo range and pseudo range rate derived based on the satellite positioning signal of another antenna AT (for example, the antenna AT having the second largest received power (signal strength of the satellite positioning signal)) are acquired from the satellite navigation processing unit 114 (Step S114).

  Next, the determination unit 120 determines whether the pseudo range and the pseudo range rate can be acquired in the process of S114 (step S116), and when it is determined that the pseudo range and the pseudo range rate can be acquired, the process of S108 described above is performed. Returning to the process, it is repeated to compare the pseudo range and the pseudo range rate acquired from the satellite navigation processing unit 114 with the pseudo range and the pseudo range rate predicted by the prediction unit 118.

  On the other hand, when the determination unit 120 can not acquire the pseudo range and the pseudo range rate in the process of S114, or when the antenna AT which has already acquired the observation value is removed, the selectable antenna AT remains. If not (when all are selected), the pseudo range and pseudo range rate between the satellite SAT (N) selected as the process target and the rocket 1 in the current processing cycle of the flowchart, the satellite navigation arithmetic processing unit It prohibits using for the satellite positioning by 114 (step S118). By such processing, for example, when the number of antennas AT is three, the determination unit 120 makes the predicted value and the threshold value or more out of the observed values of each of the three antennas AT for a certain artificial satellite SAT (N) Search the observation values that do not diverge in a round-robin manner, and even if there is an observation value that does not deviate by more than a threshold value even if one, allow the observation value to be used for satellite positioning, do not deviate by more than a threshold value If no observation value exists, it is prohibited to use all observation values for the satellite SAT (N) for satellite positioning. In this way, satellite positioning can be performed excluding the highly probable observation value including an error due to multipath until the next processing cycle of the flowchart.

  Next, the determination unit 120 determines whether the temporary parameter N is 8 or more (step S120). If the temporary parameter N is less than 8, the determination unit 120 returns to the process of S104 described above, increments the temporary parameter N, and changes the satellite SAT (N) to be processed. For example, when the artificial satellite SAT (1) is selected as the processing target when the temporary parameter N is 1, the artificial satellite SAT (2) is selected as the processing target in the present processing. By repeating the process as described above, it is determined whether or not multipath is generated for each observation value of the eight satellites SAT.

  On the other hand, when the determination unit 120 determines that the temporary parameter N is 8 or more, the satellite navigation arithmetic processing unit 114 uses the observed values permitted to be used by the determination unit 120 to determine the position and velocity of the rocket 1. It derives (step S122). The process of this flowchart is complete | finished by this.

  Although the process of the above-described flowchart has been described as being repeatedly executed at a predetermined cycle after the rocket 1 is launched, the present invention is not limited to this. For example, the process is terminated when the rocket 1 reaches a predetermined altitude or more It is also good. The predetermined altitude is, for example, a high altitude (for example, an altitude of tens of thousands of kilometers) which is generally said to be unlikely to cause multipath. By terminating the process at such an advanced level, the processing load can be reduced.

[Simulation test]
The applicant of the present application carried out the simulation test described below. FIG. 6 is a diagram showing an example of a simulation result. In the figure, (a) shows a simulation result to which the present method is not applied, and (b) shows a simulation result to which the present method is applied. In any of the figures, the vertical axis represents velocity error [m / s], and the horizontal axis represents time [s].

  As shown in (a), when the observation value and the prediction value are compared, and it is not determined whether the observation value is used for satellite positioning according to the comparison difference, the satellite SAT (N As the error of the pseudo range rate increases, the error of the velocity of the rocket 1 determined by satellite positioning also increases (see the section of T1).

  On the other hand, as shown in (b), when it is determined whether to use the observation value for satellite positioning according to the comparison difference by comparing the observation value and the prediction value, for example, every 3 seconds Although the error starts to increase from pseudo range to pseudo range rate, since the pseudo range rate is still less than the threshold, it is used for satellite positioning, and there is also an error in the velocity of the rocket 1 that is the positioning result. On the other hand, around 3.5 seconds, the error of the pseudo range rate exceeds the threshold, and this pseudo range rate is not used for satellite positioning, and as a result, the error of the velocity of the rocket 1 which is the positioning result decreases (See section T2).

  According to the first embodiment described above, based on one or more antennas AT that receive radio waves from each of the five or more multiple satellites SAT and the radio waves received by each of the one or more antennas AT, Satellite navigation calculation to derive pseudoranges between the satellite SAT and the rocket 1 and pseudorange rates between the satellite SAT and the rocket 1 at the time when radio waves are received, for each of a plurality of satellites SAT The pseudo range between the satellite SAT and the rocket 1 and the satellite SAT and the rocket 1 at a certain time in the future for each of the plurality of satellites SAT based on the radio wave received by the processing unit 114 and the antenna AT A prediction unit 118 configured to predict at least one of a pseudo range rate between 1 and 1; The position and velocity of the rocket 1 are calculated based on the comparison result of the observed value derived by the satellite navigation processing unit 114 based on the radio wave received by the antenna AT at By providing the compound navigation processing unit 116 for deriving, for example, multipaths occur in observed values (a pseudo range and a pseudo range rate) of one or two or three satellites SAT out of eight. Even in this case, satellite positioning can be performed by the remaining four or more satellites SAT. As a result, since the position and velocity of the rocket 1 can be derived by composite navigation without being affected by errors due to multipath, it is possible to accurately derive the position and velocity of the rocket 1 as an example of a flying object. it can.

  Further, according to the above-described first embodiment, since the processing of the above-described flowchart is repeatedly performed in a predetermined cycle after the rocket 1 is launched, this effect is suppressed even when a multipass occurs due to the smoke of the rocket 1 or the like. be able to.

Second Embodiment
The second embodiment will be described below. In the first embodiment described above, when the difference between any of one or more observation values of a certain satellite SAT and the predicted value is equal to or more than the threshold value, it is assumed that the observation value of the satellite SAT is not used for satellite positioning. explained. On the other hand, in the second embodiment, the observation value is weighted according to the difference between the observation value and the prediction value, and satellite positioning is performed using the weighted observation value, unlike the first embodiment. . That is, the second embodiment is different from the first embodiment in that it is used for satellite positioning even if the difference between the observed value and the predicted value is equal to or more than the threshold. Hereinafter, differences from the first embodiment will be mainly described, and descriptions of parts in common with the first embodiment will be omitted.

  The satellite navigation arithmetic processing unit 114 of the second embodiment assigns weights to each observation value based on the difference when the determination unit 120 compares the observation value and the prediction value. For example, the satellite navigation arithmetic processing unit 114 reduces the weight as the difference between the observed value and the predicted value increases, and increases the weight as the difference decreases. The weight given to each observation value may be, for example, a weighted sum that is 1 when the weights are summed. At this time, the weight may be zero. As a result, the degree of contribution of satellite positioning is reduced as the observed value (the observed value with a large difference from the predicted value) having a high probability that the error due to multipath is included more, and the observed value (not with the predicted value) decreases. As the difference is smaller, the contribution of satellite positioning can be improved.

  According to the second embodiment described above, since the observation value is weighted according to the difference between the observation value and the prediction value, and satellite positioning is performed using the weighted observation value, the influence of multipath is suppressed. Satellite positioning can be performed using more observation values of the artificial satellite SAT, and the position and velocity of the rocket 1 can be accurately derived.

  Generally, when the rocket 1 is placed at the launch site, radio interferences such as the lightning arrestor LT may be present in the propagation path of radio waves between the rocket 1 and the artificial satellite SAT. In this case, it may be considered that the observation value of the satellite SAT flying in a predetermined fixed direction is not used for satellite positioning. However, if the number of satellites SAT that can be captured at the time of launch of the rocket 1 is reduced, the accuracy of the position and velocity of the rocket 1 may be reduced. For example, when the rocket 1 in a stationary state transitions to a motion state, the acceleration is the largest, and more precise control is required. Therefore, it is preferable to obtain as many satellite SAT observations as possible when launching the rocket 1. In addition, since it is difficult to know in advance the direction in which the multipath error is mixed, the multipath SAT error value is included in the observation value of the satellite SAT flying in a direction different from the predetermined fixed direction. In some cases.

  On the other hand, in the second embodiment, the observation values of all the satellites SAT from the time of launch of the rocket 1 are assigned weights according to the difference from the predicted values, and all the weighted observation values Since the position and velocity of the rocket 1 are derived by utilizing the satellite positioning in the satellite positioning, the rocket 1 can be more accurately navigated while enhancing the robustness against multipath.

Third Embodiment
The third embodiment will be described below. In the first and second embodiments described above, it is determined whether or not multipath occurs in accordance with the difference between the observed value and the predicted value. On the other hand, in the third embodiment, in addition to or instead of the difference between the observed value and the predicted value, it is determined from the analysis result of the vehicle body dynamics of the rocket 1 whether or not the multipath occurs. This is different from the first and second embodiments. Hereinafter, differences from the first and second embodiments will be mainly described, and descriptions of parts in common with the first and second embodiments will be omitted.

  For example, the determination unit 120 in the third embodiment includes the maximum change amount such as the velocity, acceleration, and jerk assumed in advance in the flight environment of the rocket 1, and the change amount such as the current velocity, acceleration, and jerk of the rocket 1. Are compared to determine whether or not multipath has occurred. For example, in the East-North-Up coordinate system having the launch point of the rocket 1 as the origin, the determination unit 120 is an East axis (hereinafter, E axis), a North axis (hereinafter, N axis), and an Up axis (hereinafter, The vector decomposition of the observed value, which is a scalar quantity, to each U axis). Then, the determination unit 120 determines whether the vector-resolved observed value of each axis exceeds the threshold, and if any of the vector-resolved observed values of each axis exceeds the threshold, a multipath occurs. It is determined that

  FIG. 7 and FIG. 8 are diagrams for explaining a method of determining the presence or absence of multipath by aircraft dynamics. For example, each axis of the East-North-Up coordinate system may be provided with different threshold values. For example, a relatively large threshold Th (U) is set on the U axis when the rocket 1 propels vertically upward, and a threshold Th (E) smaller than the threshold Th (U) on the E axis and the N axis. And Th (U) are respectively set. This makes it easy to tolerate the occurrence of an error with respect to the U-axis, which is the direction in which jerk tends to occur (the direction in which the acceleration is likely to fluctuate rapidly and follow-up delay easily occur), and The occurrence of errors can be made unacceptable for the axes and the N axis. For example, in the example of FIG. 7, the vector of the observation value is equal to or less than the threshold value in each axis, and therefore the determination unit 120 determines that multipath does not occur. On the other hand, in the example of FIG. 8, the vector of the observation value exceeds the threshold value in the N axis, so the determination unit 120 determines that the multipath is generated. As described above, if the actual vehicle dynamics of the rocket 1 is larger than the vehicle dynamics of the rocket 1 assumed in advance, the determination unit 120 includes an error due to multipath in the observed value, and it is assumed as a result thereof. It can be determined that the observed value and the large observed value are derived.

  In addition, the determination unit 120 may use an observation value derived by the satellite navigation processing unit 114 based on radio waves received by the antenna AT at a certain point (hereinafter, first point) and a second point in time after the first point. Whether or not multipath occurs may be determined based on the comparison result with the observation value derived by the satellite navigation processing unit 114 based on the radio wave received by the antenna AT in. For example, when the increment between the vector value of each axis at the first time point and the vector value of each axis at the second time point is equal to or greater than the threshold, the determination unit 120 determines that multipath is generated. For example, when the pseudo range rate is large at the U axis at the first time point and the pseudo range rate is small at the E axis and the N axis, the pseudo range rate is small at the U axis at the second time point Thus, when the pseudo range rate increases in the E axis and the N axis, the rocket 1 ceases to propelled in the Up direction, and instead indicates that it has started to move in the East direction and the North direction. In such a case, since the rocket 1 performs a motion different from the motion that can normally be taken, the determination unit 120 may derive an observed value that is different from the expected observed value due to an error due to multipath. It can be determined. When it is determined by the determination unit 120 that a multipath is generated, the satellite navigation arithmetic processing unit 114, as described above, does not use the observation value including the error due to the multipath, but uses only other observation values. Perform satellite positioning.

  According to the third embodiment described above, it is determined whether multi-path is generated or not from the analysis result of the vehicle body dynamics of the rocket 1. Therefore, it is more accurate whether or not the observation value includes an error due to multi-path. It can be detected well. As a result, the position and velocity of the rocket 1 can be derived more accurately by composite navigation without being affected by errors due to multipath.

The above embodiment can be expressed as follows.
One or more antennas that receive radio waves from each of five or more multiple satellites,
Storage for storing information,
A processor that executes a program stored in the storage;
The processor executes the program to
Based on radio waves received by each of the one or more antennas, for each of the plurality of artificial satellites, the relative distance and relative velocity between the artificial satellite and the aircraft at the time of reception of the radio waves is used as an index value. Derive
Predicting, for each of the plurality of artificial satellites, an index value of at least one of a relative distance and a relative velocity between the artificial satellite and the aircraft at a future time;
The position and velocity of the aircraft are derived based on the comparison result between the index value derived based on the radio wave received by the antenna at the prediction time of the index value and the predicted index value. Flight navigation system.

  As mentioned above, although the form for carrying out the present invention was explained using an embodiment, the present invention is not limited at all by such an embodiment, and various modification and substitution within the range which does not deviate from the gist of the present invention Can be added.

  As described above, the flight navigation system according to the present invention may be mounted on a non-flying mobile body such as a car or a ship other than the flight body, as described below. Can be used as a mobile control method. In particular, in automatic driving of a car, it is useful because the position and speed of the car can be derived accurately.

The said embodiment can also be expressed as follows other than the expression mentioned above.
(1)
A mobile navigation system mounted on a non-flying mobile unit,
One or more antennas that receive radio waves from each of five or more multiple satellites,
Based on radio waves received by each of the one or more antennas, for each of the plurality of artificial satellites, the relative distance and relative velocity between the satellite and the mobile at the time of reception of the radio waves are used as index values. A first derivation unit for deriving;
A prediction unit for predicting an index value of at least one of a relative distance and a relative velocity between the artificial satellite and the moving body at a certain time in the future, for each of the plurality of artificial satellites;
The moving body of the moving body based on the comparison result of the index value derived by the first derivation unit based on the radio wave received by the antenna at the prediction time of the prediction unit and the index value predicted by the prediction unit. A second derivation unit for deriving the position and velocity;
Mobile navigation device with
(2)
It further comprises a detection unit that detects the position and velocity of the moving body based on the inertial force acting on the moving body.
The prediction unit is configured to calculate, for each of the plurality of artificial satellites, a relative distance and relative distance between the satellite and the mobile object at a certain time in the future based on the position and velocity of the mobile object detected by the detection unit. Predict at least one indicator value of the velocity,
The mobile navigation device according to the above (1).
(3)
The prediction unit is configured to, for each of the plurality of artificial satellites, the satellite and the mobile unit at a certain time in the future, based on the position and velocity of the mobile unit in the past derived by the first derivation unit. Predict at least one index value of relative distance and relative velocity,
The mobile navigation device according to the above (1).
(4)
It further comprises a detection unit that detects the position and velocity of the moving body based on the inertial force acting on the moving body.
The second derivation unit is
Among the index values derived for each of the artificial satellites by the first derivation unit, the index value corresponding to the target artificial satellite to be processed and the index value predicted for each of the artificial satellites by the prediction unit It is determined whether or not the difference from the index value corresponding to the target artificial satellite is equal to or greater than a threshold value,
When it is determined that the difference is less than the threshold value, based on the index value derived for each of the artificial satellites by the first derivation unit, and the position and velocity of the moving body detected by the detection unit. Derive the position and velocity of the moving body,
When it is determined that the difference is equal to or more than a threshold, a plurality of index values excluding the index value corresponding to the target artificial satellite from the index values derived for each of the artificial satellites by the first derivation unit And deriving the position and velocity of the moving object based on the position and velocity of the moving object detected by the detection unit.
The mobile navigation system according to any one of the above (1) to (3).
(5)
The second derivation unit is
A determination process of determining whether the difference is equal to or more than a threshold is repeated at a predetermined cycle,
When it is determined that the difference is greater than or equal to the threshold while repeating the determination process, the detection unit detects a plurality of index values excluding the index value corresponding to the target satellite until at least the next cycle. Deriving the position and velocity of the moving object based on the position and velocity of the moving object
The mobile navigation device according to the above (4).
(6)
It further comprises a detection unit that detects the position and velocity of the moving body based on the inertial force acting on the moving body.
The second derivation unit is
The difference between the index value derived for each of the artificial satellites by the first derivation unit and the index value predicted for each of the artificial satellites by the prediction unit is derived for each of the satellites,
The index value derived for each of the artificial satellites by the first derivation unit is given a weight according to the derived difference,
The position and velocity of the moving body are derived based on the index value for each of the satellites to which the weight is assigned and the position and velocity of the moving body detected by the detection unit.
The mobile navigation system according to any one of the above (1) to (3).
(7)
The second deriving unit reduces the weight as the difference is larger, and increases the weight as the difference is smaller.
The mobile navigation device according to (6) above.
(8)
The second derivation unit further includes
The position and velocity of the mobile unit are derived based on the comparison result between the index value derived by the first derivation unit and a predetermined threshold.
The mobile navigation device according to any one of the above (1) to (7).
(9)
The second derivation unit further includes
The index value derived by the first derivation unit based on radio waves received by the antenna at a first time point, and the first based on radio waves received by the antenna at a second time point after the first time point Deriving the position and velocity of the moving body based on the comparison result with the index value derived by the deriving unit
The mobile navigation device according to any one of the above (1) to (8).
(10)
A computer mounted on a non-flying mobile comprising one or more antennas receiving radio waves from each of a plurality of five or more satellites,
Based on radio waves received by each of the one or more antennas, for each of the plurality of artificial satellites, the relative distance and relative velocity between the satellite and the mobile at the time of reception of the radio waves are used as index values. Derive
Predicting, for each of the plurality of artificial satellites, an index value of at least one of a relative distance and a relative velocity between the artificial satellite and the mobile at a certain time in the future;
The position and velocity of the moving body are derived based on a comparison result of an index value derived based on radio waves received by the antenna at the prediction time of the index value and the predicted index value.
Mobile control method.

AT: antenna 100: aircraft navigation system 110: arithmetic module 112: inertial navigation arithmetic processor 114: satellite navigation arithmetic processor 116: composite navigation arithmetic processor 118: predictor 118: determination unit , 130: MPU, 140: power supply module, 150: storage unit, TM: communication device

Claims (10)

A flight navigation system mounted on a flight vehicle,
One or more antennas that receive radio waves from each of five or more multiple satellites,
Based on radio waves received by each of the one or more antennas, for each of the plurality of artificial satellites, the relative distance and relative velocity between the artificial satellite and the aircraft at the time of reception of the radio waves is used as an index value. A first derivation unit for deriving;
A prediction unit that predicts an index value of at least one of a relative distance and a relative velocity between the artificial satellite and the aircraft at a certain time in the future, for each of the plurality of artificial satellites;
The flying object is obtained based on the comparison result of the index value derived by the first derivation unit based on the radio wave received by the antenna at the prediction time of the prediction unit, and the index value predicted by the prediction unit. A second derivation unit for deriving the position and velocity;
Navigation system with an aircraft. And a detection unit that detects the position and velocity of the flying object based on the inertial force acting on the flying object.
The prediction unit determines, for each of the plurality of artificial satellites, a relative distance and relative distance between the artificial satellite and the aircraft at a certain time in the future, based on the position and velocity of the aircraft detected by the detection unit. Predict at least one indicator value of the velocity,
An aircraft navigation system according to claim 1. The prediction unit is configured to, for each of the plurality of artificial satellites, between the artificial satellite and the aircraft at a certain time in the future, based on the position and velocity of the previous air vehicle derived by the first derivation unit. Predict at least one index value of relative distance and relative velocity,
An aircraft navigation system according to claim 1. And a detection unit that detects the position and velocity of the flying object based on the inertial force acting on the flying object.
The second derivation unit is
Among the index values derived for each of the artificial satellites by the first derivation unit, the index value corresponding to the target artificial satellite to be processed and the index value predicted for each of the artificial satellites by the prediction unit It is determined whether or not the difference from the index value corresponding to the target artificial satellite is equal to or greater than a threshold value,
When it is determined that the difference is less than the threshold value, based on the index value derived for each of the artificial satellites by the first derivation unit, and the position and velocity of the flying object detected by the detection unit. Derive the position and velocity of the aircraft;
When it is determined that the difference is equal to or more than a threshold, a plurality of index values excluding the index value corresponding to the target artificial satellite from the index values derived for each of the artificial satellites by the first derivation unit Deriving the position and velocity of the aircraft based on the position and velocity of the aircraft detected by the detection unit;
The flight navigation system according to any one of claims 1 to 3. The second derivation unit is
A determination process of determining whether the difference is equal to or more than a threshold is repeated at a predetermined cycle,
When it is determined that the difference is greater than or equal to the threshold while repeating the determination process, the detection unit detects a plurality of index values excluding the index value corresponding to the target satellite until at least the next cycle. Deriving the position and velocity of the aircraft based on the position and velocity of the aircraft;
An aircraft navigation system according to claim 4. And a detection unit that detects the position and velocity of the flying object based on the inertial force acting on the flying object.
The second derivation unit is
The difference between the index value derived for each of the artificial satellites by the first derivation unit and the index value predicted for each of the artificial satellites by the prediction unit is derived for each of the satellites,
The index value derived for each of the artificial satellites by the first derivation unit is given a weight according to the derived difference,
The position and velocity of the flying object are derived based on the index value for each of the satellites to which the weight is given and the position and velocity of the flying object detected by the detecting unit.
The flight navigation system according to any one of claims 1 to 3. The second deriving unit reduces the weight as the difference is larger, and increases the weight as the difference is smaller.
The flight navigation system according to claim 6. The second derivation unit further includes
The position and velocity of the aircraft are derived based on the comparison result between the index value derived by the first derivation unit and a predetermined threshold.
The flight navigation system according to any one of claims 1 to 7. The second derivation unit further includes
The index value derived by the first derivation unit based on radio waves received by the antenna at a first time point, and the first based on radio waves received by the antenna at a second time point after the first time point Deriving the position and velocity of the aircraft based on the comparison result with the index value derived by the deriving unit;
The flight navigation system according to any one of claims 1 to 8. A computer mounted on an aircraft comprising one or more antennas for receiving radio waves from each of a plurality of five or more artificial satellites,
Based on radio waves received by each of the one or more antennas, for each of the plurality of artificial satellites, the relative distance and relative velocity between the artificial satellite and the aircraft at the time of reception of the radio waves is used as an index value. Derive
Predicting, for each of the plurality of artificial satellites, an index value of at least one of a relative distance and a relative velocity between the artificial satellite and the aircraft at a future time;
The position and velocity of the aircraft are derived based on a comparison result of an index value derived based on radio waves received by the antenna at the prediction time of the index value and the predicted index value.
Flight control method.

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