JPH11183603A - Doppler navigation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain accurate positional information, by correcting speed error due to Doppler frequency deviation based on the change of the beam length change speed when the attitude of an aircraft changes. SOLUTION: Information such as attitude, azimuth, altitude, and time of an aircraft are inputted from various kinds of sensor 9 for body information, and a synchronizer 10 corrects and synchronizes measurement deviation from three-dimensional speed information from these and a Doppler speed operator 6. A two-dimensional speed converter 11 converts the three-dimensional speed information to two-dimensional speed information being projected on a horizontal surface based on attitude and azimuth information, and a two-dimensional position calculator 6 integrates over time and obtains two-dimensional position information. A beam length change speed calculator 15 obtains the beam length change speed from various kinds of information of the synchronizer 11, and an error speed calculator 16 obtains the Doppler deviation frequency of each beam from these and obtains three-dimensional error speed information and then converts it to two-dimensional speed error information. A calculator 17 of amount of positional correction integrates it over time and adds and corrects the obtained amount of position correction and transmits accurate positional information to a switcher 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio wave mounted on an aircraft, transmitting a radio wave toward the ground surface, and detecting a reflected wave from the ground surface, that is, a Doppler shift frequency corresponding to the speed of the aircraft contained in the received radio wave. Obtaining information and improving the Doppler navigation system that supplies speed information to the host device or pilot as navigation information to be used for flight control of the aircraft, etc., together with the speed information of the aircraft, the position information of the aircraft is sent to the host device or It is possible to supply to the pilot.

[0002]

2. Description of the Related Art There are various types of navigation devices that provide flight status such as attitudes such as pitch angle and roll angle of the aircraft, azimuth of the nose, flight altitude, etc., to an upper navigation device or a pilot of the aircraft. One of them is a Doppler navigation device that provides aircraft speed information. The Doppler navigation device is a device that transmits radio waves from an aircraft to the ground surface, detects a Doppler frequency shift corresponding to the speed of the aircraft included in the reflected wave, and calculates the speed. FIG. 9 relates to the principle of this device. 1 is an aircraft, 2 is a conventional Doppler navigation device, 3 is a beam of radio waves transmitted and received by the Doppler navigation device, 4 is a ground surface, The vector is V, and the angle between the velocity vector V of the aircraft and the beam 3 is Γ. At this time, if the transmission frequency of the transmission beam 3 is ft and the radio wave propagation speed is c,
Due to the Doppler effect, the Doppler frequency shift fd included in the reflected wave is represented by Equation 1, and the velocity V is represented by Equation 2 from Equation 1.

[0003]

(Equation 1)

[0004]

(Equation 2)

Therefore, the speed V of the aircraft can be obtained by detecting the Doppler frequency shift contained in the received radio wave. The Doppler navigation device is a device that obtains the speed of an aircraft based on such a principle. In an actual device, it is necessary to decompose the speed of the aircraft into three-dimensional information that is orthogonal to each other and provide it to a higher-level navigation device or pilot. Therefore, the beams transmitted and received from the Doppler navigation device must be in three or more directions. Becomes

FIG. 10 is a diagram showing the configuration of a conventional Doppler navigation system. In the figure, 2 is the same as FIG. 9, 5 is an antenna composed of a transmitting antenna 5a and a receiving antenna 5b, 6 is a Doppler speed calculator having a transmitting / receiving function and a speed calculating function of the Doppler navigation device, and 6a is a transmission reference. A transmitter for generating a signal; 6b a receiver for amplifying a received signal;
c is a mixer that outputs the difference between the frequency of the transmission reference signal and the received signal, that is, the Doppler shift frequency, 6d is a frequency tracker that tracks the Doppler shift frequency and outputs a tracking value, and 6e is a speed that calculates the speed of the aircraft. It is an arithmetic unit. FIG.
Has shown the relationship between the velocity vector of the airframe and the beam transmission angle based on the Doppler navigation system coordinate system for a Doppler navigation system that transmits four beams to the ground surface as an example of a conventional Doppler navigation system. Things. In the figure,
1 and 2 are the same as those in FIG. 9, and the coordinate system is a coordinate system based on the Doppler navigation device mounted on the bottom surface of the fuselage of the aircraft 1 as the origin and reference. In the Doppler navigation device fixed to the fuselage,
The T-axis, the L-axis, and the V-axis correspond to the aircraft orthogonal to each other, the T-axis corresponds to the nose-oriented aircraft, the L-axis corresponds to the starboard-oriented aircraft, and the V-axis corresponds to the downward aircraft. Va is the velocity vector of the aircraft, and its components VT, VL, and VV are the projections of Va on the T axis, L axis, and V axis, respectively,
,, Are the beam projection point on the ground surface, the origin,
,, Indicate the direction of the transmitted beam, the angle formed by each beam with each of the T, L, and V axes is constant, the angle formed with the T axis is γ, the angle formed with the L axis is σ, and the V axis And the angle formed is Ψ.

Next, the operation will be described. In FIG. 10, a transmitter 6a sends a transmission reference signal of a transmission beam to a transmission antenna 5a and a mixer 6c, and a transmission radio wave is transmitted from the antenna 5a. The transmission radio wave of each beam is reflected on the ground surface and received by the antenna 5b, and the reception frequency at that time is the one that has undergone the Doppler frequency shift accompanying the speed of the aircraft. The antenna 5b outputs the received radio wave as a received signal to the receiver 6b, and the receiver 6b amplifies the received signal corresponding to each beam and outputs the amplified signal to the mixer 6c. Inside the mixer 6c, the transmitter 6a and the receiver 6b
And extracts the frequency difference between the transmission reference signal and the reception signal of the transmission beam, that is, the Doppler shift frequency included in each beam, and outputs it to the frequency tracker 6d. The frequency tracker 6d outputs the frequency tracking value to the speed calculator 6e while tracking the input frequency. In the speed calculator 6e, based on the Doppler shift frequencies of the beams in the four directions, three-dimensional speed information Va that coincides with the aircraft axis.
(VT, VL, VV) are calculated. Next, the speed calculator 6e
The internal calculation will be described.

In FIG. 11, the Doppler shift frequency contained in each reflected wave of the beam in four directions is represented by f
Assuming that d1, fd2 for fd3, and fd4 for fd4, each Doppler shift frequency is based on the contribution of the velocity component when the airframe velocity is projected onto each beam. Expression 3 is obtained from Expression 1 using the projections VT, VL, and VV on the axes coincident with the machine axis, the angles γ, σ, and す formed by each axis and each beam, the transmission frequency ft, and the speed c of the radio wave. Is obtained, and by solving Equation 3 as a simultaneous equation, Equation 4 is obtained.

[0009]

(Equation 3)

[0010]

(Equation 4)

Therefore, by substituting the Doppler shift frequencies fd1 to fd4 of the respective beams into Equation 4, it is possible to obtain a velocity component along the axis of the aircraft, that is, three-dimensional velocity information.

[0012]

FIG. 12 is a diagram for explaining a problem to be solved by the present invention. In the figure, 1,
Reference numerals 2 and 4 are the same as those in FIG. 9, reference numeral 7 is a transmission beam from the Doppler navigation device 2 fixed to the aircraft 1 during horizontal flight, and reference numeral 8 is a transmission beam when the aircraft 1 pitches.
In the conventional Doppler navigation system, for example, as shown in FIG. 12, when the aircraft 1 pitches, the beam projection point on the aircraft 1 moves, so that the beam length changes from BL1 to BL2, and the change speed is time. Equation 5 for t
Becomes

[0013]

(Equation 5)

A shift in Doppler frequency occurs due to the change in the beam length, and an error occurs in the three-dimensional velocity information obtained by the equation (4). For this reason, in the range of use in which only three-dimensional speed information is provided to a higher-order navigation device or pilot, a speed error occurs only in a short time of the attitude change of the aircraft, When the function of outputting position information by integration is added, there is a problem that the above error is superimposed on the time integration value and an error occurs in the position information.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and reduces the influence of a speed error due to a Doppler frequency shift caused by a beam length change speed that occurs when an airframe attitude changes. The purpose of the present invention is to obtain a Doppler navigation system having a function of outputting position information with high accuracy.

[0016]

In order to achieve the above object, a Doppler navigation system according to a first aspect of the present invention provides Doppler outputs of various types of aircraft information such as aircraft attitude information, azimuth information, altitude information, and time information. Input to the navigation device,
Synchronization in which three-dimensional speed information in a coordinate system based on this device and attitude information, azimuth information, and altitude information of the aircraft and in which the coordinate axes coincide with the aircraft's aircraft axis are collected at the same time based on the above time information. From the three-dimensional velocity information and direction information calculated by the Doppler velocity calculator
A two-dimensional velocity converter for calculating two-dimensional velocity information in a horizontal plane based on a certain direction, a two-dimensional position calculator for integrating two-dimensional velocity information with time to calculate two-dimensional position information, A two-dimensional speed memory that temporarily stores two-dimensional speed information and keeps storing the same when a Doppler speed calculator malfunctions, and an estimated value of two-dimensional position information by time-integrating the output of the two-dimensional speed memory A position error compensator that outputs estimated two-dimensional position information, and attitude information, altitude information,
A beam length change speed calculator that obtains the attitude change angular speed of the aircraft from the time information and calculates the beam length change speed of the radio wave transmitted from the aircraft, and obtains the Doppler shift frequency generated by the beam length change to obtain three-dimensional speed information. 3 which is the amount of error correction
An error speed calculator for obtaining two-dimensional error speed information, further calculating two-dimensional error speed information as a correction amount of an error of the two-dimensional speed information in a horizontal plane, and time-integrating the output of the error speed calculator. A position correction amount calculator that calculates the correction amount of the two-dimensional position information, and an adder that adds the two-dimensional position information of the two-dimensional position calculator and the correction amount of the two-dimensional position information of the position correction amount calculator A position output controller that constantly monitors the operation of the Doppler velocity calculator and outputs an operation state; and outputs the output of the adder or the position error compensator according to the output of the position output controller.
And a switch for selecting as dimensional position information.

Further, in the Doppler navigation system according to the second invention, the outputs of various sensors of body information such as aircraft attitude information, azimuth information, and time information are connected to the Doppler navigation system, and the aircraft attitude information, azimuth information, A synchronizer that combines three-dimensional velocity information of the aircraft in a coordinate system whose coordinate axes coincide with the axis of the aircraft in a horizontal flight state based on the time information based on the time information based on the time information; A two-dimensional speed converter for calculating two-dimensional speed information in a horizontal plane based on a certain direction from the two-dimensional speed information and the direction information, and calculating two-dimensional position information by time-integrating the two-dimensional speed information A two-dimensional position calculator that temporarily stores the two-dimensional velocity information and keeps storing the information when the Doppler velocity calculator is abnormal. A position error compensator that outputs the two-dimensional estimated position information, which is an estimated value of the two-dimensional position information, by time-integrating the output of the storage device, and the angle of incidence of the radio wave beam transmitted from the antenna to the ground surface is fixed And a posture stabilizer to keep
An attitude controller that controls the attitude of the attitude stabilizer, a position / orientation output controller that constantly monitors the operation of the Doppler velocity calculator and the attitude controller, and outputs the operating state, and according to the output of the position / orientation output controller A switch for selecting the output of the adder or the position error compensator as two-dimensional position information; and a three-dimensional velocity information in a coordinate system whose coordinate axes coincide with the axes of the aircraft in a horizontal flight state. And a speed coordinate converter for converting three-dimensional speed information in a coordinate system corresponding to the machine axis based on the time information and the attitude information.

In the Doppler navigation system according to the third aspect of the present invention, the outputs of various types of aircraft information such as aircraft attitude information, azimuth information, altitude information, and time information are connected to the Doppler navigation system, and the attitude information and azimuth of the aircraft are obtained. A synchronizer that combines information, altitude information, and three-dimensional speed information in a coordinate system that uses this device as a reference and in which a coordinate axis coincides with the axis of the aircraft as information measured at the same time based on the time information; A two-dimensional speed converter that calculates two-dimensional speed information in a horizontal plane based on a certain direction from the two-dimensional speed information and the above-mentioned direction information, and calculates two-dimensional position information by time-integrating the two-dimensional speed. A two-dimensional position calculator, a two-dimensional speed memory that temporarily stores two-dimensional speed information and keeps storing the information when the Doppler speed calculator is abnormal, and outputs a two-dimensional speed memory output. A position error compensator that integrates and outputs two-dimensional estimated position information that is an estimated value of two-dimensional position information, a low-pass filter that removes high-frequency components in an arbitrary band with respect to the output of the two-dimensional position calculator, Aircraft informationA filter controller that sets the band of the low-pass filter based on attitude information, altitude information, and time information from various sensors, a position output controller that constantly monitors the operation of the Doppler speed calculator, and outputs the operation state, And a switch for selecting the output of the low-pass filter or the output of the position error compensator as two-dimensional position information in accordance with the output of the position output controller.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a block diagram showing Embodiment 1 of the present invention. In the figure,
2, 5 and 6 are the same as those in FIG. 10, 9 is an aircraft information various sensor for obtaining aircraft attitude information, azimuth information, altitude information, and time information, 10 is the aircraft attitude information, azimuth information,
A synchronizer that combines the altitude information and the three-dimensional speed information obtained from the Doppler speed calculator 6 as information measured at the same time based on the time information. Reference numeral 11 denotes a three-dimensional speed calculated by the Doppler speed calculator. Information Va (VT, VL, VV),
A two-dimensional speed converter for calculating two-dimensional speed information in a horizontal plane based on a certain direction from the posture information and the direction information;
Reference numeral 2 denotes a two-dimensional position calculator for integrating the two-dimensional speed with time to calculate two-dimensional position information. Reference numeral 13 temporarily stores the two-dimensional speed and keeps storing the two-dimensional speed when the Doppler speed calculator is abnormal. A position error compensator for integrating the output of the two-dimensional speed memory with time and calculating two-dimensional estimated position information which is an estimated value of the two-dimensional position information when the output of the Doppler speed calculator is abnormal; Is a beam length change rate calculator that obtains the attitude change angular velocity of the aircraft from the attitude information, altitude information, and time information of the aircraft, and calculates the beam length change rate of the radio wave transmitted from the aircraft, and 16 is the Doppler shift caused by the beam length change The frequency is obtained and the error of the three-dimensional speed information is 3
An error speed calculator for obtaining two-dimensional error speed information, and further calculating two-dimensional error speed information which is an error of the two-dimensional speed information in a horizontal plane. A position correction amount calculator for calculating the correction amount of the position, an adder 18 for adding the two-dimensional speed and the position correction amount, and a position output 19 for constantly monitoring the operation of the Doppler speed calculator and outputting an operation state. The controller 20 outputs the output of the adder or the position error compensator to 2 according to the output of the position output controller.
This is a switch for selecting as dimension position information.

Embodiment 1 of the present invention is configured as described above, and transmits an electric wave to the ground surface, and obtains three-dimensional velocity information of the aircraft from the Doppler shift frequency included in the received electric wave. The operation of the speed calculator 6 is the same as that of the conventional device.

Next, a first embodiment of the present invention is provided with a function of integrating the two-dimensional velocity in a horizontal plane parallel to the ground surface obtained from the three-dimensional velocity information with time and outputting position information with few errors. Will be described.

FIGS. 2, 3, and 4 are diagrams for explaining the operation of the first embodiment. FIG. 2 shows a two-dimensional speed converter 11.
, Three-dimensional velocity information Va (VT, VL, V
FIG. 5 is a diagram for explaining conversion from V) to two-dimensional velocity information of VH (VX, VY). In the figure, 1, 2, and 4 represent FIG.
Reference numeral 21 denotes a beam of a radio wave transmitted and received by a Doppler navigation device fixed to an aircraft, 22 denotes a horizontal plane parallel to the ground surface 4 and a two-dimensional velocity obtained as an output of the two-dimensional velocity converter 11. Information is represented as a vector in this horizontal plane. FIG. 3 is a diagram for explaining the correction by the addition of the output of the two-dimensional position calculator 12 and the position correction amount calculator 17 in the adder 18, but VH (VX, V
In this case, only one of the two-dimensional velocity information of Y) is noted. In the figure, the time during which the attitude of the aircraft is changing from time t1 to time t2,
Is the true position information obtained from the time integration value of the true speed information, 24 is the position information including the error obtained as the output of the two-dimensional position calculator 12, and 25 is the above obtained as the output of the position correction amount calculator 17. Correction amount of position information including error, 2
Reference numeral 6 denotes corrected position information obtained as an output of the adder 18. Further, FIG. 4 shows that the position output controller 19 selects the output of the position error compensator 14 instead of the output of the adder 18 while the abnormality of the Doppler velocity calculator 6 has occurred, thereby obtaining a position with high accuracy. FIG. 4 is a diagram for explaining a mechanism for outputting information, but focuses on only one of the two-dimensional velocity information of VH (VX, VY) as in FIG. 3. In the figure, t3 is the time of occurrence of the abnormality, 2 before t3.
7 is position information output when the output of the adder 18 is selected, 28 after t3 is true position information output, 29
Is the output of the adder 18 whose change has become zero due to the occurrence of an abnormality,
Numeral 30 denotes estimated position information which is estimated and calculated based on the storage speed of the two-dimensional speed storage 13 and is an output of the position error compensator 14.
In FIG. 1, aircraft attitude information, azimuth information, altitude information, and time information are input from the aircraft information various sensors 9, and the synchronizer 10 receives the attitude information, the azimuth information, the altitude information, and the Doppler speed The obtained three-dimensional velocity information is corrected for a time lag, and synchronized to output the information measured at the same time. Two-dimensional speed converter 11
In FIG. 2, three-dimensional speed information Va (VT, VL, VV) obtained as three-dimensional speed information based on attitude information and azimuth information of an aircraft is projected on a horizontal plane parallel to the ground surface as shown in FIG. Two-dimensional velocity information VH (VX, V
Y). The two-dimensional position calculator 6 obtains two-dimensional position information by time-integrating the two-dimensional speed information VH. This two-dimensional position information is accurate when the aircraft continues to fly horizontally without changing its attitude,
When the aircraft makes a pitch and roll rotational movement, an error occurs in the output of the two-dimensional position calculator 12 due to the Doppler frequency shift accompanying the beam length change from the length BL1 to the BL2 as shown in FIG. The error is corrected by the following circuit. The beam length change speed calculator 15 outputs the change speed of the beam length from the attitude information, altitude information, and time information obtained via the synchronizer 10, and the error speed calculator 16 is included in the reception frequency of each beam. The Doppler shift frequency associated with the beam length change speed is obtained to obtain three-dimensional error speed information which is a correction amount of an error of three-dimensional speed information. Convert to dimensional speed error information. The position correction amount calculator 17 performs time integration of the two-dimensional error speed information output from the error speed calculator 16 and calculates the position correction amount. The adder 18 adds the output of the two-dimensional position calculator 12 including the position error due to the change in the attitude of the body as shown in FIG. 3 and the output of the position correction amount calculator 17 which is the position error correction amount, The accurate position information is transmitted to the switch 20. On the other hand, the two-dimensional speed memory 13
In this example, the two-dimensional speed information VH is temporarily stored and sent to the position error compensator 14, and the position error compensator 14 integrates the input VH with time and sends it to the switch. The position output controller 19 constantly monitors the operation state of the Doppler speed calculator 6, and outputs a Doppler operation state signal indicating a normal or abnormal operation state. The switch 20 outputs the output of the adder 18 as two-dimensional position information. When an abnormality occurs, the two-dimensional velocity storage unit 13 stores the two-dimensional velocity information immediately before the abnormality occurs, the two-dimensional velocity converter 11 and the beam length change velocity calculator 15 stop operating, and the switch 20 Outputs the output of the position error compensator 14 as two-dimensional position information.
As a result, as shown in FIG.
Thereafter, the output of the position error compensator 14 for obtaining position information from the two-dimensional velocity information recorded immediately before t3 from the output of the adder 18 whose output is constant is selected, and the occurrence of an abnormality in the Doppler velocity calculator 6 Even at the time, the accuracy of the two-dimensional position information is kept good.

Embodiment 2 FIG. FIG. 5 is a block diagram showing Embodiment 2 of the present invention. In the figure, 2, 5,
6, 9 to 14 and 20 are the same as those in the first embodiment, 31 is a posture stabilizer for keeping the antenna always on a horizontal plane, 32 is posture information and posture stabilizer 3 inputted from various sensors 9 for body information.
1 is a posture controller that controls the posture stabilizer 11 from the posture information, 33 is a position / posture output controller obtained by adding the function of monitoring the operation of the posture controller 32 to the position output controller 19 in the first embodiment, and 34 is The attitude information and the azimuth information obtained via the synchronizer, and the three-dimensional velocity information of the aircraft in a coordinate system based on this device and in which the coordinate axes coincide with the aircraft axes in the horizontal flight state of the aircraft are always input. This is a speed coordinate converter for converting into three-dimensional speed information in a coordinate system in which the coordinate axes coincide with the aircraft axis.

The second embodiment of the present invention is configured as described above, and the three-dimensional velocity information V from the Doppler velocity calculator 6 is used.
a (VT, VL, VV), VT and VL are always in a horizontal plane parallel to the ground surface. In the two-dimensional speed converter 11, VT and VL of the three-dimensional speed information are transmitted from the synchronizer 10. Conversion to two-dimensional speed information only by azimuth information, and position output controller 1 in the first embodiment
9, except for using a position / posture output controller 33 to which an operation monitoring function of a posture controller 32 is also added. 3 obtained from the arithmetic unit 6
After the measurement time deviation of the dimensional speed information is corrected and synchronized by the synchronization circuit 10, it is converted to two-dimensional speed information by the two-dimensional speed converter 11, and its output is output to the two-dimensional position calculator 12 and the two-dimensional speed. The time is integrated by the position error compensator 14 via the storage device 13 and output as two-dimensional position information to the switch 20. The position output controller 19 in the first embodiment has a function of monitoring the operation of the attitude controller 32. Based on the operation control of the two-dimensional velocity converter 11, the two-dimensional velocity memory 13 and the switch 20 based on the added Doppler operation state signal of the position / posture output controller 33, the two-dimensional selected by the switch 20 The operation of outputting the position information is the same as in the first embodiment.

FIG. 6 is a diagram for explaining the structure of the second embodiment. In the figure, 1, 3, and 4 are the same as in FIG.
Is connected to the attitude stabilizer 31 and the attitude controller 32, and is always kept horizontal regardless of the attitude of the aircraft. Θ is always constant with respect to the ground surface due to the effect of the attitude stabilizer 31 and the attitude controller 32. This is the angle between the transmitting beam that maintains the angle and the horizontal plane. In the second embodiment of the present invention, the attitude information from the body information sensors 9 and the attitude information of the attitude stabilizer are input to the attitude controller 32. The attitude controller 32 controls the attitude of the antenna 35 by outputting an attitude control signal to the attitude stabilizer 31 based on the input information, and, as shown in FIG. The angle Θ is kept constant. Also, among the three-dimensional speed information Va (VT, VL, VV), VT and VL always exist in the horizontal plane regardless of the change in the attitude of the aircraft.
1 obtains only the azimuth information from the synchronizer 10 to obtain a two-dimensional velocity VH based on a certain azimuth. Further, the speed coordinate converter 34 obtains three-dimensional speed information Va (VT, VL, VV) in a coordinate system in which the coordinate axes coincide with the axes in the horizontal flight state of the aircraft obtained via the synchronous circuit 10.
Is converted to three-dimensional velocity information Va ′ (V) in a coordinate system that always coincides with the aircraft axis, similarly to the conventional Doppler navigation system.
T ′, VL ′, VV ′) based on the time information and the attitude information from the synchronization circuit 10. With such a mechanism, it is possible to always avoid the occurrence of the Doppler frequency shift due to the speed of each beam length change accompanying the attitude change of the aircraft, and it is possible to output two-dimensional position information with good accuracy.

Embodiment 3 FIG. FIG. 7 is a block diagram showing Embodiment 3 of the present invention. In the figure, 2, 5,
6, 9 to 14, 19, and 20 are the same as those in the first embodiment.
Is a filter controller that sets and outputs a low-pass filter band based on attitude information, altitude information, and time information input from the body information various sensors 9 via the synchronizer 10, 37 is based on the output of the filter controller 36, Two-dimensional position calculator 12
Is a low-pass filter that performs low-pass filtering on the two-dimensional position information output from.

The third embodiment of the present invention is configured as described above. The attitude information, the azimuth information, the altitude information, and the three-dimensional velocity information obtained from the Doppler velocity calculator 6 are input from the various body information sensors 9. After the deviation of the measurement time is corrected and synchronized by the synchronizer 10, it is converted into two-dimensional speed information by the two-dimensional speed converter 12, and the output is output to the two-dimensional position calculator 1.
Position error compensator 1 via two- and two-dimensional velocity storage 13
, Time-integrated in the switch 4 and two-dimensional position information
0, according to the control signal of the position output controller 19,
Under the operation control of the two-dimensional speed changer 12, the two-dimensional speed storage 13, and the switch 20, the operation of outputting the two-dimensional position information selected by the switch 20 is the same as that of the first embodiment. .

FIG. 8 is a diagram for explaining the structure of the third embodiment. FIG. 8B shows VH (VX, VX) as in FIG.
In this case, only one of the two-dimensional velocity information of Y) is noted. In the drawing, reference numeral 38 denotes a filter characteristic of a cutoff frequency f1 set in the low-pass filter 37 during horizontal flight, 39 denotes a filter characteristic of a cutoff frequency f2 shifted to a lower frequency side set in the low-pass filter 37 when the body attitude changes, Reference numeral 40 denotes an output of the low-pass filter 37 which is position information including an error when the filter characteristics of the above 38 are applied without changing the setting between the body posture change sections t4 to t5, and 41 denotes the above 39 corresponding to a posture change. Is the output of the low-pass filter 37, which is the error-reduced position information when the filter characteristics are set. In the third embodiment of the present invention, the posture information from the various body information sensors 9 is input to the filter control unit 36. The Doppler frequency shift caused by each beam length change speed accompanying the attitude change of the aircraft appears as an error in the time integral value of the two-dimensional speed information in the two-dimensional position calculator 12 as a result. Also, the higher the posture change speed, the sharper, ie, the higher the frequency component. Therefore, the filter controller 36 determines the frequency component of the error based on the attitude information, the altitude information, and the time information, and outputs band setting information of the low-pass filter. The low-pass filter 37 performs a filtering process on the output of the two-dimensional position calculator 12 according to the output of the filter controller 36. In this way, as shown in FIG. 12A, when the attitude of the aircraft changes, the filter characteristic is changed from 38 to 39 to a lower frequency range, so that the frequency changes at a high frequency due to the altitude and attitude change of the aircraft.
The error in the output of the dimension position calculator 12 can be reduced,
Two-dimensional position information can be output with good accuracy as indicated by 41 in (b).

[0029]

As described above, according to the present invention, the following effects can be obtained.

According to the first invention, attitude information, azimuth information, altitude information, and time information are input to the conventional Doppler navigation device from various types of body information sensors, and a synchronous circuit, a two-dimensional speed converter, and a two-dimensional position calculation are performed. , Two-dimensional speed memory, position error compensator, beam length change speed calculator, error speed calculator, position correction amount calculator, adder, position output controller, switch The correction amount of the two-dimensional position information corresponding to the Doppler shift frequency caused by each beam length change speed due to the change is obtained, so that the two-dimensional position information can be output with good accuracy.

According to the second invention, attitude information, azimuth information, and time information are input to the conventional Doppler navigation device from various types of body information sensors, and a synchronous circuit, a two-dimensional speed converter,
By adding a two-dimensional position calculator, two-dimensional speed memory, position error compensator, adder, position / posture output controller, switch, posture controller, posture stabilizer, and velocity coordinate converter, the aircraft posture , The transmission angle between the ground surface and each beam can be kept constant, avoiding the occurrence of Doppler shift due to each beam length change speed accompanying the attitude change of the aircraft, and the two-dimensional position with good accuracy Information can be output.

According to the third aspect of the present invention, attitude information, azimuth information, altitude information, and time information are input to the conventional Doppler navigation apparatus from various types of body information sensors, and a synchronous circuit, a two-dimensional speed converter, and a two-dimensional By adding a position calculator, a two-dimensional speed memory, a position error compensator, an adder, a position output controller, a switch, a filter controller, and a low-pass filter, when the attitude of the aircraft changes, the beam length changes accordingly. The high range of the output of the two-dimensional position calculator 6 including the Doppler shift frequency due to the speed can be cut, and the two-dimensional position information can be output with good accuracy.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing conversion of a three-dimensional speed into a two-dimensional speed.

FIG. 3 is a diagram illustrating correction of position information in an adder 12;

FIG. 4 is a diagram illustrating an output of a switch when an abnormality occurs.

FIG. 5 is a block diagram showing a second embodiment of the present invention.

FIG. 6 is a diagram showing beam transmission angle control by the attitude stabilizer.

FIG. 7 is a block diagram showing a third embodiment of the present invention.

FIG. 8 is a diagram illustrating the effect of reducing errors due to a low frequency shift of the filter band when the attitude of the aircraft changes.

FIG. 9 is a diagram illustrating the principle of a Doppler navigation device.

FIG. 10 is a block diagram showing a conventional Doppler navigation device.

FIG. 11 is a diagram illustrating an example of a Doppler navigation device that transmits and receives beams in four directions.

FIG. 12 is a diagram illustrating a change in a beam length due to pitching of a body.

[Explanation of symbols]

1 aircraft, 2 conventional Doppler navigation systems, 3 radio transmission and reception beams, 4 ground surface, 5 antennas, 5a
Transmitting antenna, 5b receiving antenna, 6 Doppler velocity calculator, 6a transmitter, 6b receiver, 6c mixer,
6d frequency tracker, 6e speed calculator, 7 transmit and receive beam of length BL1 from Doppler navigation device fixed to the aircraft at a certain time, 8 transmission of BL2 length when aircraft pitched And receiving beam, 9 airframe information various sensors, 10 synchronizer, 11 two-dimensional velocity converter, 12 two-dimensional position calculator, 13 two-dimensional velocity memory, 14 position error compensator, 15 beam length change velocity calculator, 16 error speed calculator, 17 position correction amount calculator, 18 adder, 19 position output controller, 20
Switch, 21 transmitting and receiving beams from Doppler navigation equipment fixed to the aircraft, 22 horizontal plane parallel to the surface of the earth, 23 true position information, 24 position information including error,
25 correction amount of position information, 26 position information after correction, 2
7 Output of position information when output of adder 18 is selected, 28 true position information, 29 output of adder whose change becomes zero due to occurrence of abnormality, 30 position error compensator which is two-dimensional estimated position information 14 outputs, 31 posture stabilizer, 32 posture controller, 33 position / posture output controller, 3
4 Velocity coordinate converter, 35 Components of conventional Doppler navigation system always kept horizontal, 36 Filter controller, 3
7 Low-pass filter, 38 Cutoff frequency is f1
39, a filter characteristic having a cutoff frequency of f2, 40 an output of a low-pass filter serving as position information including an error, 41 an output of a low-pass filter serving as position information after error reduction.

Claims (3)

[Claims] An antenna mounted on an aircraft for transmitting radio waves toward the ground surface and receiving reflected waves from the ground surface,
A Doppler speed calculator that obtains three-dimensional speed information in a coordinate system in which a coordinate axis coincides with the aircraft axis based on its own device from the Doppler shift frequency corresponding to the aircraft speed included in the reflected wave. And, aircraft attitude information obtained from the aircraft body information various sensors, attitude information such as pitch angle, roll angle, azimuth information indicating the nose orientation, altitude information indicating flight altitude, time information is input, and the time information is input. A synchronizer that combines the three-dimensional velocity information, the attitude information, the azimuth information, and the altitude information as information measured at the same time, and a three-dimensional signal obtained by the Doppler velocity calculator.
A two-dimensional speed converter that obtains a two-dimensional speed in a horizontal plane based on a certain direction from the two-dimensional speed information and the direction information;
A two-dimensional position calculator for time-integrating the two-dimensional speed information to calculate two-dimensional position information; and temporarily storing the two-dimensional speed information and keeping the storage when the Doppler speed calculator is abnormal. A two-dimensional velocity memory, a position error compensator for time-integrating the output of the two-dimensional velocity memory and outputting two-dimensional estimated position information which is an estimated value of the two-dimensional position information, and an attitude information of the aircraft A beam length change speed calculator for obtaining the attitude change angular speed of the aircraft from altitude information and time information and calculating a beam length change speed of a radio wave transmitted from the aircraft; and obtaining a Doppler shift frequency generated by the beam length change speed. Is the correction amount of the error of the three-dimensional speed information.
An error speed calculator that obtains two-dimensional error speed information that obtains two-dimensional error speed information that is a correction amount of an error of two-dimensional speed information in a horizontal plane, and time-integrates the output of the error speed calculator. A position correction amount calculator for calculating the correction amount of the two-dimensional position information; and adding the two-dimensional position information of the two-dimensional position calculator and the correction amount of the two-dimensional position information of the position correction amount calculator. An adder, a position output controller that constantly monitors the operation of the Doppler speed calculator and outputs an operation state, and outputs the output of the adder or the position error compensator two-dimensionally according to the output of the position output controller. And a switch for selecting the position information as the position information. 2. An antenna mounted on an aircraft, transmitting radio waves toward the ground surface, and receiving a reflected wave from the ground surface,
From the Doppler shift frequency corresponding to the speed of the aircraft included in the reflected wave, three-dimensional speed information of the aircraft in a coordinate system in which the coordinate axes coincide with the axes of the aircraft in a horizontal flight state based on the own apparatus Doppler velocity calculator that obtains, attitude information such as the pitch angle and roll angle of the aircraft obtained from the aircraft body information various sensors,
A synchronizer that inputs azimuth information indicating the azimuth of the nose, time information, and synchronizes the speed, the attitude information, and the azimuth information as information measured at the same time based on the time information, and the Doppler speed calculator Two-dimensional velocity converter that obtains a two-dimensional velocity in a horizontal plane with reference to a certain azimuth from the velocity information and the azimuth information obtained as described above, and calculates two-dimensional position information by time-integrating the two-dimensional velocity information A two-dimensional position calculator,
A two-dimensional velocity memory that temporarily stores the two-dimensional velocity information and keeps storing the abnormality when the Doppler velocity calculator is abnormal; and a two-dimensional position information obtained by time-integrating the output of the two-dimensional velocity memory. A position error compensator that outputs two-dimensional estimated position information that is an estimated value of the position stabilizer; a posture stabilizer that keeps a constant angle of incidence of a beam of a radio wave transmitted from the antenna on the ground; An attitude controller for controlling the attitude,
A position / posture output controller that constantly monitors the operation of the Doppler velocity calculator and the posture controller and outputs an operation state;
A switch that selects the output of the adder or the position error compensator as two-dimensional position information according to the output of the position / posture output controller matches the coordinate axis of the aircraft axis in the horizontal flight state of the aircraft. The three-dimensional velocity information in the coordinate system is always converted to the three-dimensional velocity information in the coordinate system that coincides with the aircraft axis.
A Doppler navigation device, comprising: a speed coordinate converter that converts dimensional speed information based on the time information and the attitude information. 3. An antenna mounted on an aircraft, transmitting radio waves toward the ground surface, and receiving a reflected wave from the ground surface,
A Doppler speed calculator that obtains three-dimensional speed information in a coordinate system in which a coordinate axis coincides with the aircraft axis based on its own device from the Doppler shift frequency corresponding to the aircraft speed included in the reflected wave. And, aircraft attitude information obtained from the aircraft body information various sensors, attitude information such as pitch angle, roll angle, azimuth information indicating the nose orientation, altitude information indicating flight altitude, time information is input, and the time information is input. Based on the speed, the attitude information, the azimuth information, and the altitude information as information measured at the same time based on the synchronizer, and a certain azimuth based on the speed information and the azimuth information obtained by the Doppler speed calculator, A two-dimensional velocity converter that obtains a two-dimensional velocity in a horizontal plane, a two-dimensional position calculator that performs time integration of the two-dimensional velocity information to calculate two-dimensional position information, Two-dimensional velocity memory that temporarily stores the velocity information of the Doppler velocity calculator and retains the storage when the Doppler velocity calculator is abnormal, and an estimated value of two-dimensional position information obtained by time-integrating the output of the two-dimensional velocity memory A position error compensator that outputs two-dimensional estimated position information, a low-pass filter that removes high-frequency components from the output of the two-dimensional position calculator, and the various body information sensors obtained through the synchronizer. A filter controller that sets the band of the low-pass filter based on the attitude information of the position, a position output controller that constantly monitors the operation of the Doppler velocity calculator and outputs an operation state, and a filter that responds to the output of the position output controller. A switch for selecting the output of the low-pass filter or the output of the position error compensator as two-dimensional position information.