JP3770259B2 - Positioning device - Google Patents

Description

  The present invention relates to a positioning device.

  The conventional positioning device selects a positioning satellite based on the geometrical arrangement of the positioning satellite with respect to itself. (For example, Non-Patent Document 1).

Chan-Woo Park, Jonathan P. How, “Quasi-optimal Satellite Selection Algorithm for Real-time Applications” ION GPS 2001, September 2001)

  The technique described in Non-Patent Document 1 has a problem that, when a mobile body equipped with a positioning device accelerates, tracking of a positioning satellite positioned in the acceleration direction of the mobile body is removed, and accurate positioning cannot be performed. .

  An object of the present invention is to provide a positioning device that selects a positioning satellite in a direction in which tracking of a positioning satellite is unlikely to be missed due to acceleration of a moving object.

  A positioning apparatus according to the present invention includes a direction calculation unit that calculates the presence direction of each positioning satellite relative to itself based on reception signals from a plurality of positioning satellites, a movement calculation unit that outputs the movement direction of the self, A selection unit that preferentially selects the positioning satellite that has a large angle between the direction in which the positioning satellite exists and the direction of movement of the self, and calculates the self-position based on the received signal from the positioning satellite selected by the selection unit A positioning calculation unit.

  As described above, according to the present invention, it is possible to provide a positioning device that selects a positioning satellite in a direction in which tracking of a positioning satellite is difficult to be removed by acceleration of a moving body.

Embodiment 1
1 to 11 are diagrams showing a first embodiment of the present invention. FIG. 1 is a block diagram illustrating a configuration example of the positioning device 100.

  From the positioning satellite 1 (1A, 1B,... 1N), satellite orbit information called a navigation message necessary for positioning, information on time (clock error), and the like are transmitted. The positioning satellite 1 includes a GPS (Global Positioning Systems) satellite, a quasi-zenith satellite, and a geostationary satellite.

  The positioning device 100 includes a receiver 2, a direction calculation unit 3, a motion calculation unit 4, a selection unit 5, and a positioning calculation unit 6.

  The receiver 2 receives each navigation message from a plurality (N) of positioning satellites 1 (1A, 1B... 1N), and outputs the received information.

  The direction calculation unit 3 is, for example, a specific positioning satellite 1A (or 1B,... 1N) among received signals from a plurality (N) of positioning satellites 1 (1A, 1B,... 1N) received by the receiver 2. Based on the received signal from the positioning device 100, the presence direction of the specific positioning satellite 1A with respect to the positioning device 100 is calculated and the result is output. The calculation method will be described later.

  In some cases, the direction calculation unit 3 determines the presence direction of the specific positioning satellite 1A (or 1B,... 1N) after the specified time Δt seconds and the positioning device 100 based on the orbit information of the specific positioning satellite 1A. You may calculate and output the result. Similarly, the direction calculation unit 3 outputs the presence directions of the positioning satellites 1B,.

  The existence direction here is the direction of a specific positioning satellite 1A viewed from the position of the positioning device 100, and may be represented by a vector. The direction calculation unit 3 outputs the calculated presence direction as presence direction information. Hereinafter, the existence direction is referred to as an existence direction vector, but it is not limited to a vector. Moreover, the direction of the positioning device 100 viewed from the positioning satellite 1A may be used.

  The motion calculation unit 4 calculates the motion direction of the positioning device 100, and outputs the calculated motion direction as motion direction information. The calculation method will be described later. The movement direction may be expressed as a vector. The direction of motion refers to the direction of acceleration or the direction of jerk obtained by differentiating acceleration. Hereinafter, an example in which the motion direction is an acceleration vector will be described. However, the present invention is not limited to acceleration or a vector.

  The selection unit 5 receives the presence direction vector obtained for the positioning satellites 1A, 1B,... 1N output from the direction calculation unit 3 and the acceleration vector output from the motion calculation unit 4. Based on this input information, the angle formed by the existence direction vector and the acceleration vector is calculated, and the positioning satellites 1 having the largest angle are selected in descending order and preferentially selected (K). In addition, when the formed angle exceeds 90 degrees, a value obtained by subtracting from 180 degrees is referred to as an angle formed below.

  The magnitude of the angle formed may be calculated by taking, for example, the inner product of the presence direction vector and the acceleration vector. The selection unit 5 outputs information on a plurality (K) of positioning satellites 1 selected with priority. That is, information indicating which positioning satellite 1 should be selected is output.

  The positioning calculation unit 6 includes a plurality of (K) positioning satellites 1A, 1B,... Which are preferentially selected by the selection unit 5 among navigation messages from a plurality (N) of positioning satellites 1 received by the receiver 2. Calculate the position of the positioning device 100 based on the navigation message from 1N. The calculation of the position will be described later.

  The positioning satellite 1 includes a GPS satellite, a quasi-zenith satellite, and a geostationary satellite. A GPS satellite is a satellite used in a positioning system using an orbital altitude of about 20,000 km, a period of 12 hours, and 24 earth-orbiting satellites. GPS satellites transmit navigation messages that are necessary for positioning.

  The quasi-zenith satellite orbits once a day according to the rotation of the earth so as to have an inclination angle of about 45 degrees from the equator plane. Note that the inclination angle from the equator plane may be arbitrarily set depending on the design.

  In addition, three aircraft are arranged so as to be 120 degrees apart at the ascending intersection eclipse (intersection with the equator plane). The trajectory of the quasi-zenith satellite orbit projected onto the ground surface is such that the quasi-zenith satellite draws an “eight-shape” or “tears pattern” that intersects the equator when the ground is fixed. It is going around. FIG. 2 shows, as an example, the locus of the quasi-zenith satellite orbit projected onto the ground surface in the case of “eighth-shaped”.

  The three quasi-zenith satellites are located above Japan seamlessly by changing (meeting) every eight hours, but with different orbital planes. Also, when considering the region in Japan, there are always quasi-zenith satellites with elevation angles of 70 degrees or more in large urban areas such as Tokyo and Osaka.

  Orbital elements when there are three quasi-zenith satellites are expressed as follows. The orbital length radius is about 42,164 km for all three orbits, that is, a period of about 23 hours and 56 minutes, the eccentricity is 0.09923 ± 0.0008 for all three orbits, the orbital inclination angle is 45 degrees for all three orbits, and the ascending point red longitude is 120. The near point argument is set to 270 degrees for all three trajectories, and the near point separation angles are 129.23 degrees, 0.36 degrees, and 230.41 degrees, respectively.

  The quasi-zenith satellite may transmit a navigation message necessary for positioning similar to the GPS satellite. Further, correction information used for high-accuracy positioning may be transmitted. There is a difference between the actual distance to the positioning satellite 1 and the distance to the positioning satellite 1 calculated based on the electromagnetic waves transmitted from the positioning satellite 1 due to the ionosphere and the like. The correction information is information relating to the difference as an example.

  A geostationary satellite is a satellite arranged in a geostationary orbit 36,000 km from the equator. Geostationary satellites may transmit navigation messages that are required for positioning similar to GPS satellites

  The direction calculation unit 3 calculates the presence direction vector of each of a plurality (N) of positioning satellites 1 from the positioning device 100. Hereinafter, a specific positioning satellite 1A will be described as an example for explanation. In calculating the existence direction vector, information on the position of the positioning device 100 and the position of the positioning satellite 1A is required.

  The position of the positioning device 100 may be information that the positioning device 100 holds in advance, or may be calculated from the received signal of the receiver 2 using the principle of positioning using a normal positioning satellite 1. When the position of the positioning device 100 is held in advance, the position of the positioning device 100 after time Δt seconds from the current time (t0) may be used as necessary.

  When calculating the position of the positioning device 100 using the principle of positioning using the normal positioning satellite 1, temporary temporary position information is obtained. In other words, the position of the positioning device 100 is finally calculated by the positioning calculation unit 6 using the positioning satellite 1 selected by the selection unit 5, but temporarily by the positioning satellite 1 arbitrarily selected as the previous stage. Thus, the position of the positioning satellite 100 is calculated.

  The position of the positioning satellite 1A may be calculated from the orbit information of the positioning satellite 1A included in the navigation message. If necessary, the position of the positioning satellite 1A after the time Δt seconds from the present time (t0) may be used from the orbit information of the positioning satellite 1A.

  As described above, the position of the positioning device 100 and the position of the positioning satellite 1A can be obtained. The existence direction vector can be calculated from the position of the positioning device 100 obtained here and the position of the positioning satellite 1A.

  The positioning principle by the positioning satellite 1 is shown below. In order to measure the position of the positioning device 100 three-dimensionally, it is necessary to receive the navigation message transmitted from at least four positioning satellites 1 by the receiver 2. The receiver 2 measures the time until the navigation message transmitted from the positioning satellite 1 reaches the receiver 2 for each positioning satellite 1 (1A, 1B... 1N). From each measured time, the distance to each positioning satellite 1 (1A, 1B... 1N) and the receiver 2 is calculated, and positioning is performed.

  As an example, the case where the center of the earth is used as a reference will be described. It is assumed that the position r of the positioning device 100 is (X1, Y1, Z1) with respect to the earth center. Further, it is assumed that the position rs of the positioning satellite 1 is (X2, Y2, Z2) with respect to the center of the earth. In this case, the presence direction vector s from the positioning device 100 to the positioning satellite 1 can be expressed as (X2-X1, Y2-Y1, Z2-Z1) from s = rs-r. Of course, the reference axis need not be centered on the earth, and may be set arbitrarily.

  The acceleration vector of the positioning device 100 output from the motion calculation unit 4 may be information held in advance by the positioning device 100 or information actually measured. Details will be described later.

  However, the acceleration vector of the positioning device 100 needs to be in the same coordinate system as the presence direction vector from the positioning device 100 to the positioning satellite 1.

  Next, the selection unit 5 will be described. The selection unit 5 preferentially selects the positioning satellite 1 having a large angle between the presence direction vector of each of the plurality (N) of positioning satellites 1 and the acceleration vector from the positioning device 100. Here, the necessity of increasing the angle formed will be described below.

  The positioning satellite 1 is moving in orbit. Further, the positioning device 100 may also be moving. For this reason, the received signal from the positioning satellite 1 undergoes a Doppler shift. This Doppler shift differs depending on the speed of the positioning satellite 1 and the positioning device 100.

  The normal receiver 2 is provided with a band pass filter. If the band of the band-pass filter is wide, a wide band frequency can be received, but noise increases. Conversely, if the band is narrow, only a narrow band frequency can be received, but the noise is reduced. Normally, noise is proportional to the 1/2 power of the frequency band. The band of the bandpass filter is determined by the design in consideration of the band width and noise.

  The speed is different for each positioning satellite 1, and the received signal of the receiver 2 has a different Doppler shift as a result. That is, the receiver 2 adjusts the center wavelength of the bandpass filter according to the positioning satellite 1 and receives the signal from the positioning satellite 1 at the center of the bandpass filter.

  The above will be described with reference to FIG. FIG. 3 is a diagram illustrating an image of a transmission wave of the positioning satellite 1, a reception wave of the receiver 2, and a bandpass filter band. The actual signal from the positioning satellite 1 is equal to or less than the noise level, but FIG. 3 shows the signal intensity increased for explanation. The signal from the actual positioning satellite 1 is picked up from the noise level by despreading the spectrum.

  FIG. 3A is a diagram showing an image of the transmission frequency of the positioning satellite 1 and the reception frequency of the receiver 2, where the vertical axis represents the signal intensity and the horizontal axis represents the frequency. The center frequency of the transmission wave 7 from the positioning satellite 1 is f1, and the center frequency of the reception wave 8 at the receiver 2 is f2. The difference between the center frequencies f1 and f2 is due to the Doppler shift.

  FIG. 3B shows a band 9 of the bandpass filter of the receiver 2. The band 9 of the bandpass filter is rectangular for explanation. The actual bandwidth may be determined by design. FIG. 3 (c) shows the received wave 10 that has passed through the band 9 of the bandpass filter of FIG. 3 (b). Since the center frequency f2 of the received wave 8 matches the center frequency f2 of the band 9 of the bandpass filter, the signal strength is obtained even after passing through the bandpass filter.

  FIG. 3D shows a case where the Doppler shift is changed for some reason. The received wave 11 is obtained by shifting the received wave 8 by Δf. FIG. 3 (e) shows a received wave 12 in which the received wave 11 has passed through the band 9 of the bandpass filter. Since the center frequency f2 + Δf of the received wave 11 does not match the center frequency f2 of the band 9 of the bandpass filter, the signal intensity passing through the bandpass filter is weak.

  If the center frequency f2 of the received wave 8 is suddenly shifted, the receiver 2 cannot keep track of the positioning satellite. As described above, since the signal transmitted from the positioning satellite 1 is weak, correlation processing is performed in the receiver 2.

  Tracking the received signal means moving the reception frequency so that the correlation is maximized. If the Doppler shift changes abruptly, the receiver 2 cannot track the received signal. That is, if the center frequency of the received wave 8 is suddenly shifted, the receiver 2 cannot track the received signal.

  If the receiver 2 cannot keep track of the positioning satellite, the receiver 2 enters a search for the next satellite. As a result, positioning satellites used for positioning are switched, resulting in discontinuity in the positioning calculation results.

  FIG. 4 is a diagram illustrating an example in which the positioning device 100 cannot track the positioning satellite 1. A situation in which the positioning device 100 mounted on the moving body 13 cannot keep track will be described with reference to FIG.

  The moving body 13 is moving in the direction of the moving body central axis 200 with an acceleration ab. The moving body central axis 200 is an axis defined uniquely for the moving body, and may be arbitrarily determined. In FIG. 4, as an example, the axis in the length direction is the moving body central axis 200.

  The mobile body 13 is provided with the antenna 14 of the receiver 2. When viewed from the antenna 14, the angle between the specific positioning satellite 1A and the moving body central axis 200 is Ea. Further, when viewed from the antenna 14, the angle formed between the specific positioning satellite 1B and the moving body central axis 200 is Eb.

  The acceleration ata in the positioning satellite 1A direction is ab sin (Ea), the acceleration atb in the direction of the positioning satellite 1B is ab sin (Eb), and ata> atb. This indicates that when the acceleration in the direction of the positioning satellite 1A is compared with the acceleration in the direction of the positioning satellite 1B, the former acceleration increases.

  That is, the change in the Doppler shift of the received signal of the positioning satellite 1A in the receiver 2 is larger than that of the received signal of the positioning satellite 1B. The Doppler shift of the received signal is determined by the speed of the positioning satellite 1 or the moving body 13. If the speed of the positioning satellite 1 or the moving body 13 is constant, the Doppler shift of the received signal is constant. When acceleration occurs, the speed changes every moment, so the Doppler shift changes with time. Of course, when jerk, which is a derivative of acceleration, is generated, the speed changes every moment, so the Doppler shift changes with time.

  When receiving a signal from the positioning satellite 1A having a large change in Doppler shift, the receiver 2 is more likely to remove the tracking than receiving a signal from the positioning satellite 1B having a small change in Doppler shift. That is, in order for the receiver 2 not to remove the tracking of the positioning satellite 1, it is preferable that the angle formed by the presence direction vector and the acceleration vector of the positioning satellite 1 is large.

  In the selection unit 5, for each of a plurality (N) of positioning satellites 1 (1A, 1B,... 1N), an angle formed by each direction vector and acceleration vector of each positioning satellite is sequentially calculated, and the angle formed Positioning satellite 1 with a large is selected with priority.

  As described above, four positioning satellites are required to three-dimensionally determine the position of the moving body, so four positioning satellites having a large angle are preferentially selected.

  The specific calculation of the selection unit 5 is shown below. The position of the positioning device 100 with respect to the earth center is assumed to be r. Further, if the position of the i-th positioning satellite 1i with respect to the earth center is rsi, the existence direction vector si is expressed by Equation (1).

  Therefore, the unit vector ei of the existence direction vector si of the i-th positioning satellite 1i is expressed by Equation (2).

  Here, an acceleration vector of the positioning device 100 having the same coordinate system as the unit vector ei of the existence direction vector is assumed to be an. An angle Ei formed by the unit vector ei of the existence direction vector of the i-th positioning satellite 1i and the acceleration vector an is expressed by Equation (3).

  In the selection unit 5, the positioning satellite 1i having a large angle Ei formed by the unit vector ei of the existence direction vector si of the i-th positioning satellite 1i and the acceleration vector at is selected in descending order, and a plurality (K) of satellites are preferentially selected. To do.

  In order to improve positioning accuracy, the geometrical arrangement of positioning satellites is important. In other words, the positioning accuracy does not increase even if a plurality of positioning satellites in the same direction are used. In order to improve positioning accuracy, each positioning satellite needs to be geometrically separated.

  The selection unit 5 can set a threshold value atm that can be allowed by the acceleration in the positioning satellite direction in consideration of the acceleration that does not remove the tracking of the receiver 2 described above. That is, the receiver 2 does not remove the tracking if the acceleration is equal to or less than the threshold value atm. Here, first, the acceleration ati in the i-th positioning satellite 1i direction is calculated. The acceleration ati can be calculated by equation (4).

  Next, the excess degree D is calculated using the equation (5), and a positioning satellite that can be tolerated by acceleration in the positioning satellite direction is selected. If the positioning satellite 1 having the excess D = 0 based on the equation (5) is used, tracking is not removed.

  If there are more than four positioning satellites 1 with the excess degree D = 0 in equation (5), the geometrical arrangement of these positioning satellites 1 may be selected. If the number of positioning satellites 1 with an excess degree D = 0 falls below four, tracking may be out of place compared to the case of the excess degree D = 0, but from a positioning satellite 1 with a smaller value of the excess degree D Select four aircraft in sequence. That is, four or more positioning satellites 1 that are preferentially selected by the selection unit 5 are preferably four or more.

  The positioning calculation unit 6 performs positioning based on the navigation message from the positioning satellite 1 used for positioning selected by the selection unit 5. The receiver 2 may be used for receiving the navigation message. The positioning in the positioning calculation unit 6 may use the above-described principle of positioning by the positioning satellite 1. The processing content in the positioning calculation unit 6 may be performed by the receiver 2.

  Further, based on the high-precision positioning information from the quasi-zenith satellite, the positioning calculation unit 6 may measure the position of the positioning device 100 with high accuracy. High-accuracy positioning refers to positioning that is one or more digits more accurate than single positioning of GPS satellites, and is corrected by the above-described positioning correction information.

  FIG. 5 is a block diagram illustrating another example of the positioning device. As an example, the motion calculation unit 4 includes a motion direction measurement unit 15 and a reference axis conversion unit 16. That is, the motion calculation unit 4 outputs a motion direction measurement unit 15 that outputs the motion direction based on the central axis of the positioning device 100, and a reference axis conversion unit that converts the motion direction based on the moving body central axis into a motion direction based on the inertial axis. 16. The central axis reference is a coordinate system based on the above-described central axis. Further, the inertia axis reference will be described later.

  The motion direction measurement unit 15 only needs to output the motion of the positioning device 100 in the three-dimensional direction with reference to the moving body central axis. For example, the motion direction measurement unit 15 may be an accelerometer that can output acceleration. Of course, the known reference axis may be used as long as it has a known reference axis without using the moving body central axis as a reference.

  Further, the motion direction measurement unit 15 may be the same reference axis as the presence direction vector by the direction calculation unit 3. In this case, the reference axis conversion unit 16 is not necessary.

  Taking the case where the reference axis of the movement direction measuring unit 15 is the moving body central axis reference as an example, the processing in the reference axis converting unit 16 will be described. The reference axis conversion unit 16 converts the reference axis based on the attitude angle of the positioning device 100. The posture angle is indicated by an inertia standard. The inertia reference here refers to the same coordinate system as the existence direction vector. In the above, the existence direction vector is a coordinate system based on the center of the earth.

  When the roll angle of the attitude angle of the positioning device 100 is φ, the pitch angle is θ, and the yaw angle is ψ, a conversion matrix C for converting the moving body center axis reference to the inertial axis reference is expressed by Expression (6). Note that the roll angle φ, the pitch angle θ, and the yaw angle ψ are rotation angles on the X, Y, and Z axes that are the three axes of the positioning device 100.

  Note that the posture angle of the positioning device 100 may be a measured value of the current posture angle, or information held in advance. Information held in advance will be described later.

  If the acceleration vector of the positioning device 100 based on the moving body central axis output from the motion direction measuring unit 15 is ab, the acceleration vector at which is the same as the inertial axis reference, that is, the existing direction vector, can be expressed by Expression (7).

  As described above, the acceleration vector in the central axis reference direction of the moving body 13 can be converted into an acceleration vector in the same coordinate system as the existence direction vector. In this way, even if the existence direction vector and the acceleration vector are different in coordinate system, it can be converted into the same coordinate system.

  Although the movement direction measuring unit 15 is provided in FIG. 5, the value may be used as long as the direction of the positioning device 100 can be predicted in advance. Specifically, it will be described with reference to the block diagram of the positioning device shown in FIG. FIG. 6 is a block diagram illustrating a configuration example of the positioning device 100.

  As an example, the motion calculation unit 4 includes a first table 17, a motion direction output unit 18, and a reference axis conversion unit 16. The first table 17 stores the movement direction based on the central axis of the positioning device 100 in association with time. The movement direction output unit 18 outputs the movement direction based on the central axis of the positioning device 100 after a specified time Δt seconds from the movement direction stored in the first table 17.

  That is, the motion calculation unit 4 stores the first table 17 that stores the motion direction based on its own central axis in association with time, and the motion based on its own central axis after a predetermined time from the first table 17. A movement direction output unit 18 that outputs a direction, and a reference axis conversion unit 16 that converts the movement direction based on its own central axis from the movement direction output unit 18 into a movement direction based on an inertial axis.

  When the moving body 13 is a flying body, the propulsion device is burned and accelerated immediately after the flying body is launched. After combustion is completed, the vehicle decelerates due to the effects of air resistance and gravity. The combustion time of the propulsion device mounted on the flying object and the output of the propulsion device are determined by design. For this reason, it is possible to predict in advance the acceleration applied to the flying object after reaching the target after the flying object is launched. Of course, the speed and jerk applied to the flying object can be predicted in advance.

  FIG. 7 is an example of acceleration applied to the flying object based on the combustion time and output of the flying object propulsion device. In FIG. 7, the horizontal axis t indicates time, and the vertical axis ab indicates the acceleration of the moving body 13. The attached characters x, y, and z on the vertical axis indicate the direction, the X direction indicates the front of the moving body, the Y direction indicates the lower side of the moving body, and the Z direction indicates the left direction of the moving body.

  The time t0 on the horizontal axis in FIG. 7 indicates the time immediately before the launch of the flying object. Immediately after launching the flying object, the acceleration increases rapidly. The fact that the acceleration abx in the x direction is negative at time t1 indicates that the vehicle is decelerating due to air resistance or gravity as combustion of the propulsion device ends.

  The first table 17 stores a movement direction based on its own central axis in association with time. As an example, the first table 17 stores information on acceleration in the X, Y, and Z directions shown in FIG. Of course, the first table 17 may store information on speed and jerk. Moreover, you may memorize | store in the 1st table 17 combining the information regarding speed, acceleration, and jerk as needed.

  FIG. 8 shows an example of the movement direction stored in the first table 17, and shows the acceleration direction of the positioning device 100 in association with time. In addition, you may determine the reference | standard of a movement direction arbitrarily. As an example, the center axis 200 of the moving body 13 is used as a reference.

  In FIG. 8, accelerations abx, aby, and abz in the X, Y, and Z directions of the moving body are stored for each time. The time interval may be arbitrarily determined according to the design. Note that time t0 in FIG. 8 indicates the time immediately before the launch of the flying object.

  Since the acceleration of the moving body 13 changes from moment to moment, it is more based on the acceleration of the positioning device 100 after the specified time Δt seconds than on the current acceleration measured by the motion direction measuring unit 15 described above. The receiver 2 is less likely to miss tracking.

  If it is known that the tracking is lost before Δt seconds, it is possible to switch to the next satellite during Δt seconds when tracking is lost. In the current system, Δt is about 5 seconds, but may be arbitrarily determined according to the design.

  As described above, the positioning satellite can be selected based on the acceleration information of the mobile object that is held in advance, and the positioning device 100 can select the positioning satellite 1 that does not deviate from the tracking of the positioning satellite by the acceleration of the mobile object. it can.

  Next, a case where the posture angle of the moving body 13 is held in advance will be described. FIG. 9 is a block diagram illustrating an example of the reference axis conversion unit 16. The reference axis conversion unit 16 includes a second table 19 and an attitude angle reference conversion unit 20. That is, the second table 19 that stores its own posture angle in association with the time, and outputs its own posture angle after a predetermined time Δt from the second table 19, and based on the output, the central axis of its own And a posture angle reference axis conversion unit 20 that converts the reference movement direction into the inertial axis reference movement direction.

  As described above, when the moving body 13 is a flying body as an example, since the acceleration applied to the moving body is known in advance, the attitude angle of the flying body from the launching of the flying body until reaching the target can be known in advance.

  Hereinafter, a case where the attitude angle of the positioning device 100 is known in advance will be described. FIG. 10 is an example of the attitude angle of the flying object based on the combustion time and output of the flying object propulsion device. The horizontal axis t in FIG. 10 indicates time, and the vertical axis indicates the posture angle of the moving body 13. The posture angle, φ, θ, and ψ on the vertical axis indicate the roll angle, pitch angle, and yaw angle, respectively. The time t0 on the horizontal axis in FIG. 10 indicates the time immediately before the launch of the flying object.

  The second table 19 stores information on the posture angle shown in FIG. 10 for each time. FIG. 11 shows the attitude angle of the positioning device 100 stored in the second table 19 as an example, and the time.

  Since the acceleration of the moving body 13 changes from moment to moment, the receiver 2 removes the tracking based on the posture angle of the positioning device 100 after the specified time rather than based on the current measured value of the posture angle. Less.

  Therefore, in the posture angle reference conversion unit 20, the moving body central axis reference is determined based on the posture angle of the moving body after a specified time Δt from the present out of the posture angle information of the moving body stored in the second table 19. Convert to inertial axis reference.

  As described above, the positioning satellite can be selected based on the attitude angle information of the mobile body that is held in advance, and the positioning apparatus 100 can select the positioning satellite that does not deviate from the tracking of the positioning satellite due to the acceleration of the mobile body. it can.

  The positioning device of this embodiment configured as described above can achieve the following effects.

  The positioning device includes a direction calculation unit 3 that calculates the presence direction of each positioning satellite 1 relative to itself based on reception signals from a plurality of positioning satellites 1, a movement calculation unit 4 that outputs the movement direction of itself, and positioning A selection unit 5 that preferentially selects a positioning satellite 1 having a large angle between the direction in which the satellite 1 exists and the direction of movement of the satellite 1 and the self-position is determined based on a received signal from the positioning satellite 1 selected by the selection unit 5. A positioning calculation unit 6 for calculating, and by positioning the positioning satellite, a positioning satellite in a direction in which tracking of the positioning satellite is difficult to be removed can be selected by acceleration of the moving body.

  The motion calculation unit 4 outputs a motion direction measurement unit 15 that outputs a motion direction based on its own central axis, and converts the motion direction based on its own central axis from the motion direction measurement unit 15 into a motion direction based on an inertial axis. A reference axis conversion unit 16 and select a satellite based on its own direction of movement.

  The motion calculation unit 4 stores a first table 17 that stores a movement direction based on its own central axis in association with time, and a movement direction based on its own central axis after a predetermined time from the first table 17. A movement direction output unit 18 for outputting, and a reference axis conversion unit 16 for converting the movement direction based on the central axis from the movement direction output unit 18 into a movement direction based on the inertial axis, after a specified time The satellite can be selected based on its own position.

  The reference axis conversion unit 16 outputs a second table 19 that stores its own posture angle in association with time, and outputs its own posture angle after a predetermined time from the second table 19, and based on the output An attitude angle reference axis conversion unit 20 that converts the movement direction based on the central axis of the self into a movement direction based on the inertial axis, and selecting a satellite based on the attitude of the self after a predetermined time. it can.

Embodiment 2
FIG. 12 is a diagram showing a second embodiment of the present invention. In the first embodiment, the excess degree D at a certain temporary point is calculated by the equation (5). In the present embodiment, by calculating the excess degree D at a plurality of times, when the moving body 13 is a flying object, the optimum positioning satellite 1 is selected over the entire flying time.

  The positioning device shown in FIG. 12 will be described below. The direction calculation unit 3 calculates the presence direction of each positioning satellite 1 relative to itself based on the received signals from the plurality of positioning satellites 1.

  The first table 17 stores the movement direction of its own central axis in association with time. The movement direction output unit 18 outputs the movement direction based on its own central axis from the first table 17 after a predetermined plurality of hours.

  The second table 19 stores its posture angle in association with time. The posture angle reference axis conversion unit 16 causes the second table 19 to output its own posture angle after a plurality of prescribed hours, and based on the output, the plurality of central axis reference movement directions are converted into inertial axis reference motion directions. Convert to motion direction.

  The multiple selection unit 21 calculates the angle formed by the presence direction of the positioning satellite 1 at a plurality of times output from the direction calculation unit 3 and the movement direction at the plurality of times output from the attitude angle reference conversion unit 16, The positioning satellite 1 having a large angle formed in the plurality of calculated times is preferentially selected.

  The positioning calculation unit 6 calculates its own position based on the received signal from the positioning satellite selected by the multiple selection unit 21.

  The direction calculation unit 3 and the attitude angle reference axis conversion unit 20 output a direction vector and an acceleration vector for each Δt from the time t0 when the flying object is launched. In some cases, the direction vector and the acceleration vector may be output from the direction calculation unit 3 and the posture angle reference axis conversion unit 20 in accordance with a request from the multiple selection unit 21. The multiple selection unit 21 calculates the excess degree D for a plurality of hours according to the equation (8).

  The positioning satellite 1 having the excess D = 0 based on the formula (8) does not remove the tracking of the positioning satellite 1 due to the acceleration of the positioning device 100. If there are more than four positioning satellites 1 with the excess degree D = 0 in equation (8), the geometrical arrangement of these positioning satellites 1 may be selected.

  If the number of positioning satellites 1 with an excess degree D = 0 falls below four, tracking may be out of place compared to the case of the excess degree D = 0. Select four aircraft in sequence. That is, it is preferable that the number of the positioning satellites 1 to be preferentially selected by the selection unit 5 is four or more.

  The positioning calculation unit 6 performs positioning of the positioning device 100 based on the information from the multiple selection unit 21. In this way, the positioning satellite 1 can be selected in consideration of the time during which the flying object is flying.

  When the moving body 13 is a flying body, the moving body 13 is launched vertically or horizontally, and after launching, the posture is changed to a trajectory toward the target direction. The antenna 14 provided in the moving body 13 can receive only the radio waves of the positioning satellite 1 within a certain angle from above the antenna surface. Therefore, when the attitude angle of the moving body changes, the positioning satellite 1 that can be received by the antenna 14 changes.

  FIG. 13 is a diagram showing a receivable area by the antenna of the mobile body 13 when the attitude angle of the mobile body 13 changes. In FIG. 13, the antenna 14 having a specific reception characteristic mounted on the mobile body 13 can receive radio waves from the positioning satellite 1 located in the conical surfaces 22 </ b> A and 22 </ b> B with the apex angle Em from above. For this reason, when the mobile body 12 is at the position A in FIG. 13, it is possible to receive radio waves from the positioning satellite 1A.

  Next, when flying to position B in FIG. 13, the attitude angle of the moving body 13 changes, and the positioning satellite 1A cannot enter the conical surface 22B of the apex angle Em. That is, the electromagnetic wave from the positioning satellite 1A cannot be received. As described above, when the attitude changes during the flight, the satellites that can be used for positioning may change.

  If the unit vector representing the upper surface direction of the antenna 14 is db, the apex angle Ei representing the direction of the positioning satellite 1 from the upper surface of the antenna 14 can be calculated by Equation (9).

  Note that ei in Expression (9) indicates a unit vector of the i-th positioning satellite 1 calculated by Expression (2). C represents the direction cosine matrix calculated by the equation (6).

  When the maximum apex angle receivable in the GPS antenna to be used is Em, it can be determined that reception is possible if Ei is smaller than Em. That is, by selecting a satellite with the excess degree D = 0 in the equation (10), the positioning satellite 1 that cannot be received due to the change in the attitude of the moving body can be excluded from the selection candidates.

  The positioning device of this embodiment configured as described above can select a positioning satellite in a direction in which tracking of a positioning satellite is difficult to be removed due to acceleration of a moving object by considering a plurality of times.

  Furthermore, a positioning satellite can be selected in consideration of the antenna receivable area.

It is a block which shows the structural example which shows Embodiment 1 of the positioning apparatus concerning this invention. It is a figure which shows an example of the ground surface locus | trajectory of a quasi-zenith satellite. (a) The figure which showed the image of the transmission frequency of a positioning satellite, and the reception frequency of a receiver, (b) The figure which showed the band of the band pass filter, (c) The figure which shows the received wave which passed the band pass filter (D) is a figure which shows the received wave which the reception wave shifted (DELTA) f, (e) is a figure which shows the reception wave which the reception wave which shifted (DELTA) f passed the band pass filter. It is a figure which shows an example in which a positioning apparatus becomes unable to track a positioning satellite. It is a block which shows Embodiment 1 of the positioning apparatus concerning this invention. It is a block which shows Embodiment 1 of the positioning apparatus concerning this invention. It is a figure which shows an example of the calculation result of the acceleration added to a flying body based on the combustion time and output of a flying body propulsion apparatus. It is a figure which shows the movement direction of a positioning apparatus matched with the time memorize | stored in the 1st table. It is a block diagram which shows Embodiment 1 of the reference axis conversion part concerning this invention. It is a figure which shows an example of the calculation result of the attitude | position angle of a flying body. It is a figure which shows the movement direction of a positioning apparatus matched with the time memorize | stored in the 2nd table. It is a block diagram which shows Embodiment 2 of the positioning apparatus concerning this invention. It is the figure which showed the receivable area | region by the antenna of a moving body when the attitude | position angle of a moving body changed.

Explanation of symbols

1 positioning satellite, 2 receiver, 3 direction calculation unit, 4 motion calculation unit, 5 selection unit, 6 positioning calculation unit, 7 transmission wave, 8 reception wave, 9 band pass filter band, 10 reception through band pass filter Wave, 11 received wave, 12 received wave passed through bandpass filter, 13 moving body, 14 antenna, 15 motion direction measuring unit, 16 reference axis converting unit, 17 first table, 18 motion direction output unit, 19 second Table, 20 attitude angle reference conversion unit, 21 multiple selection unit, 22A in conical surface, 22B in conical surface, 100 positioning device, 200 moving body central axis direction.

Claims (5)

A direction calculator that calculates the presence direction of each positioning satellite relative to itself based on received signals from a plurality of positioning satellites;
A motion calculation unit that outputs the direction of movement of itself;
A selection unit that preferentially selects the positioning satellites having a large angle between the direction of presence of the positioning satellites and the direction of movement of the self;
A positioning calculation unit that calculates a self-position based on a received signal from a positioning satellite selected by the selection unit;
Positioning device equipped with. The motion calculation unit is a motion direction measurement unit that outputs a motion direction based on its own central axis,
A reference axis conversion unit that converts the movement direction based on the central axis from the movement direction measurement unit into a movement direction based on an inertial axis;
The positioning device according to claim 1, comprising: The motion calculation unit includes a first table that stores a motion direction based on its own central axis in association with time;
A direction-of-motion output unit that outputs a direction of motion based on the center axis of the self after a specified time from the first table;
A reference axis conversion unit that converts the movement direction based on the central axis from the movement direction output unit into a movement direction based on an inertial axis;
The positioning device according to claim 1, comprising: The reference axis conversion unit stores a second table that stores its posture angle in association with time;
A posture angle reference axis conversion unit that outputs the posture angle of the self after a predetermined time from the second table, and converts the movement direction of the central axis based on the output to the movement direction of the inertial axis based on the output;
The positioning device according to claim 2, further comprising: A direction calculator that calculates the presence direction of each positioning satellite relative to itself based on received signals from a plurality of positioning satellites;
A first table that stores a movement direction based on its own central axis in association with time;
From the first table, a movement direction output unit that outputs a movement direction based on its own central axis after a plurality of predetermined hours;
A second table that stores its posture angle in association with time;
Posture angle reference axis conversion which outputs the posture angle of the self after a prescribed plurality of hours from the second table and converts the motion directions based on the plurality of central axes into motion directions based on the inertial axis based on the output. And
The angle formed by the positioning satellite existing direction at a plurality of times output from the direction calculation unit and the movement direction at the plurality of times output from the attitude angle reference conversion unit is calculated, and the calculated plurality of times A plurality of selection units for preferentially selecting the positioning satellites having a large angle formed by
A positioning calculation unit that calculates a self-position based on a received signal from a positioning satellite selected by the plurality of selection units;
Positioning device equipped with.

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