JPH0612259B2 - Gyro compass device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a gyro compass device, in particular, a so-called strap-down type gyro compass device in which a gyro which is a sensor and an accelerometer are directly attached to a navigation body such as a vehicle or a ship, and The gyro and accelerometer are on a stabilized platform, which aims to reduce the settling time for a platform-type gyrocompass device that is attached to the vehicle via a gimbal system.

[Prior Art] First, an example of a conventional strap-down type gyro compass device for a ship will be described with reference to FIG. It consists of a gyro unit (1a) having three gyros (X-gyro, Y-gyro and Z-gyro) directly attached to the navigation body of a ship or the like, and a digital conversion circuit (1b) for converting its output into a digital quantity. Similarly to the angular velocity detector (1), three accelerometers (X-
An accelerometer (2a) having an accelerometer, a Y-accelerometer and a Z-accelerometer) and an acceleration detector (2) composed of a digital conversion circuit (2b) for converting its output into a digital quantity are used to detect an inertial signal. It constitutes a part (3), which detects the movements of the earth and the navigation body and outputs angular velocity signals and acceleration signals, respectively. The output signals of the angular velocity detecting section (1) and the acceleration detecting section (2) are input to the gyro compass calculating section (4).

In the gyro compass calculator (4), the angular velocity detector
(1) The angular velocity signal is used for rotation correction and compass calculation unit (6)
Is output to the direction cosine calculator (5) together with the corrected torqueing signal obtained through the second coordinate conversion calculator (10). The direction cosine calculator (5) is a direction cosine between the coordinate axes of the navigation body (roll axis, pitch axis, yaw axis) and the earth coordinate axes (north-south axis, east-west axis, vertical axis at the point where the navigation body is located). Output a signal. This direction cosine signal is supplied to the first coordinate conversion calculation section (7) together with the acceleration signal from the acceleration detection section (2). This converts the acceleration in the navigation body coordinate axis direction into acceleration components a _N , a _E in the axial direction of the earth coordinate system, that is, the north-south and east-west axial directions, and outputs the acceleration components a _N , a _E.

On the other hand, the log signal obtained from the speedometer (11) of the navigation vehicle via the conversion circuit (12) is used together with the azimuth signal from the gimbal angle calculation unit (13) to which the direction cosine signal is input, and the speed component force. and input to the arithmetic unit (15) decomposes in the north-south and east-west direction of the log component _{V 'N, V' E.} This log component _V'N ,
Supply V _'E estimated position calculation unit (16), where it performs an operation of integration such, it more, and outputs the estimated position of the navigation body.

Further, the log output components V ′ _N and V ′ _E and the acceleration components a _N and a _E are corrected and compared in the acceleration correction calculation section (17), and their respective differences, that is, the inclination errors θ _N , θ _E is obtained, and these and the known rotation angular velocity and the estimated position from the estimated position calculation unit (16) are used as the rotation correction and compass calculation unit (6).
The angle deviation between the earth coordinate system, which is considered as the calculation unit, and the earth coordinate system of the actual navigation body is converged to zero by the gyro compass loop. Among these tilt errors θ _N and θ _E , the tangent plane of the earth coordinate system, which is considered as the arithmetic unit, is inclined about the east-west axis with respect to the tangent plane at the position of the navigation body The tilt error θ _N corresponds to the tilt error, and the tilt error θ _E corresponds to the tilt around the north-south axis. Therefore, in response to the tilt errors θ _N and θ _E , a loop for rotating the earth coordinate system, which is considered as the arithmetic unit, around the vertical axis to bring it closer to the earth coordinate system of the actual navigation body, The finger north loop of the gyro compass, the loop trying to approach the east-west axis to the dumping group of the gyro compass,
Loops that try to get closer to the north-south axis correspond to the east-west level system, respectively.

Of these, a system composed of two loops corresponding to the tilt error θ _N , that is, a finger north loop and a damping group is called gyrocompassing.

The role of the second coordinate conversion calculation unit (10) is to convert the rotation command about each axis into components about the roll, pitch, and yaw axes of the navigation body in which the actual gyro axis exists.

On the other hand, the direction cosine signal from the direction cosine calculation unit (5) is converted into attitude angle signals such as the azimuth angle, pitch angle, and roll angle of the navigation vehicle in the gimbal angle calculation unit (13) and sent to the external required department. Is output.

Next, the platform type gyro compass will be described. In addition, this explanation will be made in the case of the platform type gyro compass, which is the gyro compassing described above.

FIG. 4 shows an example thereof, which has a structure in which a uniaxial degree of freedom gyro is placed on the platform (5 '). The example of FIG. 4 is also a gyrocompass with an integrator. In the gyro compass shown in FIG. 4, not one gyro but at least two known so-called "uniaxial degree-of-freedom gyros" are used. Therefore, first, the "1-axis degree of freedom gyro" will be briefly described. In the example of FIG. 4, there is a uniaxial degree of freedom gyro indicated by (Y) in the center, and a gyro (100) is built in it. Many elements such as pickups, torquers, etc. are built into the inside of an actual 1-axis DOF gyro.
Although it is complicated, the gyro itself with 1-axis of freedom is well known, so the description of its contents will not be given here.
Basically, a 1-axis DOF gyro is a 3-axis, that is, a 1-axis DOF gyro (Y).
s), an input shaft (I _Y ), an output shaft (O _Y ), and an electrical input terminal and an output terminal. The uniaxial degree of freedom gyro (Y) is an outer casing (110) around the input shaft (I _Y ).
) Is sensitively detected, and an electric signal is generated from its output terminal. When the gyro (Y) is in the position shown in FIG. 4, if the entire gyro (Y) tries to rotate around the input shaft (I _Y ) together with the platform (5 ′) to which it is fixed. For the above reason, a signal is output from the output terminal, and this output passes through the resolver (58) and the amplifier (47) as shown by the dotted line in FIG.
Is amplified by and is absorbed by the servo motor (57) to control it, and this movement is transmitted to the vertical ring (14 ′) via the gear (g) and the shaft (51), and the vertical shaft (53 ′) ), Turn the platform (5 ') and cancel the turning around the axis (I _Y ) of the first gyro (Y). Therefore, the platform (5 ') has a property of continuing to take a fixed posture around the axis (I _Y ) with respect to outer space. If the axis (I _Y ) is offset by about 90 ° due to the relative displacement between the platform (5 ') and the vertical ring (14') and becomes parallel to the axes (59) and (59 '), the gyro ( The output signal of Y) must reach the servo motor (56) via the amplifier, and the servo control around the axis (I _Y ) becomes impossible. In this way, the servo motor (5
The combined output of 6) and (57) allows the output signal of the gyro (Y) to be controlled by the amplifier (4) so that the gyro (Y) can always control the axis (I _Y ) of the platform (5 ').
It is the role of the resolver (58) to distribute to 6) and (47). In addition, another one-axis gyro (Z)
This input shaft (I _Z ) on the platform (5 ′)
The rotation of the platform (5 ') around the gyro (Z) is sensed by the gyro (Z), and its output signal is amplified by the amplifier (45) and drives the servomotor (55) through the path shown by the dotted line. , This also moves the platform (5 ′) around the axis (I _Z ) via the gear (g ₁ ), so that again the platform (5 ′) is constant about the axis (I _Z ) with respect to outer space. It has the property of maintaining posture. First
In the example shown, the other one perpendicular to the axes (I _Y ) and (I _Z ).
There is also a 1-axis degree of freedom gyro (X) around the axis,
The stabilization of the platform (5 ') is also realized, but this is not related to the finger north movement, so the description is omitted. Thus, with respect to outer space, two accelerometers (x) and (y) as well as three gyros are fixed on the platform (5 ') stabilized around three axes. In each of the figures, accelerations in the directions of the arrows (ax) and (ay) are detected, and an electric signal proportional to this is generated. Again, an accelerometer that detects east-west acceleration
Since (y) has no direct relation to the finger north movement, its explanation is omitted. On the other hand, the accelerometer (x) detects the acceleration in the direction of the arrow (ax), that is, the direction of the spin axis (Ys) of the uniaxial degree of freedom gyro (Y), so that the platform (5 ')
As shown in the same figure, if the inclination angle θ of the spin axis (Ys) from the horizontal plane is very small, the output of the accelerometer (x) shows the component of the earth gravity acceleration in the angle θ direction. Further, when the navigation body equipped with the gyro compass device is in motion, a value including the motion acceleration component in the spin axis (Ys) direction is output as an output signal.

By the way, in the example of FIG. 4 as well, there is the same one as the acceleration correction calculation unit (17) described in the strapdown gyro compass. The same is _true for the log output component V'N. Therefore, the output of the accelerometer (x) and the log output component V '
_The acceleration correction calculation unit (17) corrects and compares _N with each other to obtain the difference between them, that is, the inclination error θ _N , and output it.

On the other hand, the one-axis degree-of-freedom gyro has an input terminal as described above, and if a command angular velocity signal is electrically given to this, if the servo system works around the input axis, , Each platform (5 ') has the property of precessing around the input shaft at the commanded angular velocity. The output of the acceleration correction calculation unit (17), that is, the inclination error θ _N , is indicated by an amplifier (3
1), (32), (35 '), and an amplifier (3
When the outputs of 1 ') and (32') are combined by the amplifier (33 ') and input to the gyro (Z) with one axis of freedom,
The platform (5 ') produces a precession φ around the axis (I _Z ), ie the axis (53'). Similarly, if the output of the amplifier (35 ') is returned to the uniaxial degree of freedom gyro (Y), the platform (5')
It is possible to pre-session around the axis (I _Y ) in the direction of decreasing inclination. Therefore, the amplifier (31 ')
Is a proportional amplifier, the gain of which is K, and the amplifier (32)
Is an integrator, the time constant of which is K / T _I , and the amplifier (35) is a proportional amplifier whose gain is μ. The spin axis (Ys) of the gyro (Y) in FIG. ), Settled to the north and horizontally.

On the other hand, the posture angle signals such as the direction angle, pitch angle, roll angle, etc. of the platform (5 ') and the navigation body (attached via the housing (28)) are output by the angle transmitter of each axis supporting the platform. To be done.

The gyro compass having two types of structures has been described above as an example.

The gyro compass loop in the above example is originally a non-linear system that interferes with the three axes of the vertical axis, north-south axis, and east-west axis. And the east-west level system is separated.

The east-west level system in the platform type gyrocompass of the above example is a system that stabilizes the platform (5 ') around another axis perpendicular to the axes (I _Y ) and (I _Z ). The gyro (X) having the degree of freedom of axis and the accelerometer (y) for detecting the acceleration in the east-west direction make the level error in the east-west direction of the platform (5 ') zero. Since this east-west level system is irrelevant to the present invention, its explanation is omitted.

Next, for the purpose of explaining the present invention, when the above two examples of gyrocompassing are represented by a block diagram for control engineering, the two examples are equivalent and can be represented as shown in FIG. After that, this fifth
It will be described with reference to the drawings.

Gyrocompassing (GC) will be described with reference to the block diagram of FIG.

When there is an initial heading error (γ ₀ ), the gyro of the east-west axis (6) is measured via the angular velocity Ωcosλ of the horizontal rotation component (Ω is the rotation velocity of the earth and λ is the latitude of the local point where the navigation body is located).
0), this east-west axis gyro (60) tilts the gimbal around the north-south axis. The north-south axis accelerometer (61) detects this tilt and outputs it as a tilt proportional signal. At this time, the north-south axis accelerometer (61) adds and outputs the motion acceleration of the navigation body in the north-south axis direction. The output signal of the accelerometer (61), the acceleration-correction unit (17), the north-south axis component V _'N log signals, is corrected, the inclination error theta _N is obtained. This tilt error θ _N , after being latitude-corrected as is well known, is passed through a finger north gain (62) (gain is K) and a finger north integrator (63) (this constant is k / T ₁ ) to obtain the vertical axis. The vertical axis gyro (64) is rotated until it is fed back to the gyro (64) and the east-west level axis gyro (60) no longer detects a horizontal rotation component. This is the Shihoku loop.
Since the vibration is not damped by this alone, the tilt error θ _N is damped by being fed back to the east-west axis gyro (60) via the damping gain (65) or this gain μ. This is the Damping Group.

In this way, the gyro compassing (GC)
With the finger north loop and the damping group, the heading error and the level error can be reduced to zero.

[Problems to be solved by the invention]

The gyrocompassing (GC) represented by the block diagram of FIG. 5 is Laplace-transformed according to the control engineering calculation method (S is a Laplace operator), and the azimuth error γ (s) is calculated with respect to the initial azimuth error γ ₀ . When obtained, the following equation is obtained.

The motion of the azimuth error in the equation (1) can be obtained by examining the root of the characteristic equation in which the denominator of the equation (1) is set equal to 0. Therefore, S ³ + μgS ² + KΩgS + KΩg / T _I = 0. ).

Since the coefficients of this equation (2) are all positive, the equation (2) must have at least one negative real root. Now, letting this be -a (a> 0), equation (2) can be expressed in the following form.

(S + a) (S ² + 2ξωnS + ωn ² ) = 0 (3) That is, the characteristic equation of the gyrocompassing (GC) represented by the equation (2) is the exponential function solution represented by the equation (3). It can be seen that it is composed of a secondary vibration system having a time constant a, a damping constant ξ, and a natural period ωn. The time constant a corresponds to the finger north integration time constant K / T _I.

If the finger north integrator (63) is not provided, the equation (2) becomes S ₂ + μg S + KΩG = 0 (4), which can directly correspond to the secondary vibration system.

S ² + 2ξωnS + ωn ² = 0 (5) Now, the gyrocompass that has been put into practical use is designed based on a natural period of, for example, a Schlar period of 84.4 minutes and a half-period damping rate of 0.3. Determine the damping gain μ, finger north gain K, and finger north integration time constant K / T _I in equation (2).

By the way, it has been stated that the static determinate motion with respect to the initial azimuth error γ ₀ in the gyrocompassing (GC) equation (1) is determined by the characteristic equation, and this is performed at the time of design. Therefore, in order to reduce the settling time of the azimuth error, it is necessary to shorten the natural period and increase the damping.

However, shortening the natural period and decreasing the half-cycle attenuation rate (increasing the attenuation) means increasing the damping gain μ, the finger north gain K, etc., and the error due to the disturbance increases, so There is a limit. Therefore, the settling time of the gyro compass is constrained, for example, on the condition that the natural period is set to 84.4 minutes and the half period attenuation rate is set to 0.3. That is, conventionally, it has been impossible to shorten the settling time of the gyro compass to less than 1.5 hours, for example.

[Means for solving problems]

Therefore, the present invention intends to provide a gyro compass device having a short settling time, which comprises an inertial signal detecting section,
A gyro compass device having a log signal generator and a gyro compass calculator or an azimuth transmitter for calculating outputs of the log signal generator and outputting an estimated position signal of the latitude at which the tilt error and inertia signal detector is located. Then, an estimator (71) is provided, which is supplied with the estimated position signals of the inclination error θ _N and the latitude, generates an estimated value of the azimuth error based on these signals, and estimates the azimuth error. The gyro compass device is configured to remove the azimuth error in a short time by subtracting the value into the azimuth angle from the gyro compass calculation unit or the azimuth angle transmitter.

[Action]

In the gyro compass device of the present invention, the estimator (7
The tilt error θ _N and the latitude calculated value of the estimated position are supplied from the gyrocompass device (70) to 1), and the estimator (71) outputs the estimated value of the bearing error from this. By subtracting the estimated value of this azimuth error from the azimuth angle of the outgoing angle (roll angle, pitch angle and azimuth angle) output as the relative angle of the navigation vehicle with respect to true north and the local horizontal system, the azimuth angle The azimuth error included in can be offset. At this time, the heading error estimation value of the estimator (71) gradually approaches the heading error of the gyro compass with time, and finally matches, but the time until this match is the settling time of the heading error of the gyro compass. Compared to this, it is a sufficiently short time.

Therefore, by attaching this estimator (71) to the gyro compass, the settling time of the heading error of the gyro compass has been controlled by the natural period and the half-period damping coefficient of the gyro compass in the past. In the present invention, the estimated time until the estimated orientation error value of the estimator (71) matches the orientation error is changed. This estimated time can be set arbitrarily as will be described later, so that if the time is set to be sufficiently shorter than the settling time of the gyro compass (for example, 10 minutes), the settling time of the gyro compass can be significantly shortened.

〔Example〕

An example of the gyro compass device according to the present invention will be described with reference to FIG. In the present invention, the conventional gyro compass is used as it is, and the estimator (71) is attached to it. For the above reason, the gyro compass has the code (7
0) and the description thereof is omitted.

However, since the basic characteristics of the gyro compass device are not changed even if the finger north integrator (63) is removed, the finger north integrator (63) is omitted.

The estimator (71) is supplied with the tilt error θ _N and the latitude calculated value of the estimated position from the gyrocompass device (70), and outputs the estimated value of the azimuth error based on this. By adding the estimated value of this bearing error to the bearing angle output from the gyro compass device (70) as the relative attitude angle of the navigation vehicle with respect to true north and the local horizontal system in the adder (72), The azimuth error included in the azimuth can be offset.

Therefore, in the statically determinative motion with respect to the initial azimuth error, the statically determinative time of the gyrocompass azimuth error has conventionally been governed by the natural period and the half-cycle attenuation rate of the gyrocompass, but in the present invention, Is changed to the estimated time until the heading error estimated value of the estimator (71) matches the heading error.

With reference to FIG. 5, the representative of the gyro con passing (GC) by the _{equation, N = -μθ N + Ωcos λγ} ‥‥ (A1) = -kθ N ‥‥ (A2) θ N slope error is directly obtained, γ is the heading error that cannot be obtained directly, μ is the damping constant for forming the damping group, k is the finger north constant for forming the finger north loop, Ω is the earth rotation speed, λ is the gyro compass device Latitude.

Further, the acceleration component generated by the motion of the navigation body is corrected by the acceleration correction calculation unit (17) and therefore cannot be expressed in the formula.

Estimator (71) has an estimated value filter to an observer for calculating an estimated azimuth error gamma _est and (71a) smoothing the ripple of the estimated heading error gamma _est (71b).

The observer (71a) is a gyrocompassing (GC)
Equations (A1) and (A2) of Eq. (1) have a mathematical model including an estimated tilt error θ _Nest and an estimated heading error γ _est , and calculate the deviation between the input tilt error θ _N and the estimated tilt error θ _Nest. , The deviation is multiplied by an appropriate gain so that the deviation converges to 0 in a shorter time than the gyro compass cycle, and the feedback is fed back to the mathematical model.

As a result, when the deviation is almost zero, the tilt error θ _N and the estimated tilt error θ _Nest substantially coincide with each other, and a static definite motion is performed.

At this time, the azimuth error γ performs a static definite motion constrained by the equations (A1) and (A2), while the estimated azimuth error γ _est is also constrained by a mathematical model equivalent to the equations (A1) and (A2). Therefore, the same static motion as the bearing error γ is performed.

Therefore, an unknown bearing error γ can be obtained by taking out the estimated bearing error γ _est of the observer (71a).

Next, the observer (71a) will be described using equations.

From the formulas (A1) and (A2), the state quantity X (t) is expressed as follows: (t) = A (t) X (t) (A3) where the state quantity X (t) is The matrix A (t) is Here, since the cos λ term changes depending on the latitude λ, the matrix A (t) is time-varying.

Also, since the state quantity X (t) that can be detected is x ₁ (t),
The output y (t) is y (t) = CX (t) (A6) where the matrix C is C = [10] ... (A7) Therefore, the mathematical model of the gyrocompassing (GC) Was obtained from the equations (A3) to (A7).

Therefore, the mathematical model used by the observer (71a) is (t) = A '(t) Z (t) (A8) where the state quantity Z (t) is the estimated value of the state quantity X (t). Yes, The matrix A '(t) is Here, λ ′ is an estimated value of the latitude λ of gyrocompassing (GC) and corresponds to an estimated position signal.

The deviation ERR between the inclination error θ _N and the estimated inclination error θ _Nest is ERR = θ _N −θ _Nest = y−CZ (t) (A11) The deviation ERR is multiplied by the gain G and fed back to the mathematical model (A8). The formula is that of the observer (71a). That is, (t) = A ′ (t) Z (t) + G · ERR (A12) where the gain G is an appropriate constant, State quantity X (t) of equation (A3) and estimated state quantity Z of equation (A12)
Taking the differentiation of the difference from (t), (t) − (t) = A ′ (t) Z (t) + G ・ (y-CZ (t))-A (t) X (t) ＝ (A '(t) -GC) Z (t) -A (t) -GC) X (t) = F · (Z (t) -X (t)) ... (A14) where matrix A' (t) uses the same value as the matrix A (t).

The matrix F is as follows: F = A-GC (A15) (A14) Integrating Z (t) = X (t) + e ^Ft (Z (0) -X (0)) (A16) where Then, X (0) and Z (0) are initial values at the time of startup, respectively. Therefore, by selecting the gain G so that the e ^Ft term converges to 0 in a shorter time than the gyrocompass period, the estimated state quantity Z (t) coincides with the state quantity X (t) in a short time. To do.

Therefore, the estimated heading error γ _est of the observer (71a) can be obtained in a short time during the static definite motion of the gyrocompassing (GC).
Thus, the azimuth error γ can be estimated.

On the other hand, the estimated value filter (71b) is a low-pass filter having a time constant T ₂ and is configured by n1 stages.
It has the function of attenuating the ripple of the estimated heading error which is the output of a).

If the ripple component of the heading error does not matter, the estimation value filter (71b) is not necessary.

〔The invention's effect〕

By adding the azimuth error estimated by the estimator (71) to the azimuth transmission angle, the static settling time was constrained by the natural period of the compass and the half-period damping coefficient, etc. It can be replaced by the convergence time of the short-term estimator. Further, since this estimator (71) does not change or affect the specifications and characteristics of the target compass,
The conventional gyro compass design has no disadvantages.

[Brief description of drawings]

FIG. 1 is a block diagram of an example of the present invention, FIG. 2 is a block diagram of a main part thereof, FIG. 3 is a block diagram of a conventional strap-down type gyro compass device, and FIG. 4 is a conventional platform type gyro. FIG. 5 is a perspective view of the compass, and FIG. 5 is a block diagram of the gyro compassing thereof. In the figure, (GC) is a gyrocompassing stem,
(70) is a gyro compass, (71) is an estimator, (71a)
Is an observer, and (71b) is an estimated value filter.

Claims (1)

[Claims] 1. An inertial signal detecting unit, a log signal generating unit, and outputs of an inclination error and a latitude position where the inertial signal detecting unit is located by performing arithmetic processing on the outputs of the inertial signal detecting unit and the log signal generating unit. In a gyrocompass device having a gyrocompass calculator and an azimuth transmitter, an estimator for inputting the estimated position signals of the tilt error and latitude and calculating and outputting an estimated value of the azimuth error is provided. Has a mathematical model equivalent to the gyro compass, calculates the deviation between the estimated tilt error and the tilt error of the mathematical model corresponding to the tilt error, and the deviation becomes zero in a shorter time than the cycle of the gyro compass. It is configured to multiply the deviation by an appropriate gain so as to converge and feed it back to the mathematical model, and when the deviation is substantially zero, it corresponds to the heading error. The estimated azimuth error of mathematical expression models gyrocompass apparatus characterized by being configured to modify the orientation by subtracting from the azimuth signal from the azimuth transmitter.