JPH07234235A - Velocity measuring apparatus for submerged navigating body - Google Patents

Abstract

PURPOSE:To enhance velocity measuring accuracy by reducing the effects of integral errors. CONSTITUTION:A velocity measuring apparatus 1 comprises an inertial device 11 and a velocity measuring portion 13, the inertial device 11 comprising a gyrocope 7, an accelerometer 6 and an inertia data computing part 10, the velocity measuring portion 13 comprising a first 14 and second 15 velocity measuring part and a traveling state judging part 16. The inertia data computing part 10 computes an inertial velocity V1 from both acceleration and angular velocity and, using as a reference value the corrected inertial velocity VI inputted from the first velocity correcting part 14, computes the velocity VI through further correction during each steady-state traveling period. The first velocity correcting part 14 outputs the inertial velocity VI to the outside during each acceleration/deceleration period, and computes an inertial velocity VI' through correction during each steady-state traveling period by using as a reference value a corrected mechanical velocity VP' inputted from the second velocity correcting part 15. The second velocity correcting part 15 computes the mechanical velocity VP=K'N by correcting a mechanical velocity VP=KN (K is a coefficient and N is the rotation speed of a propulsion device) using the inertial velocity VI during each steady-state traveling period, and outputs the mechanical velocity VP' to the outside.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed measuring device for underwater vehicles, and more particularly to reducing measurement error, that is, improving accuracy.

[0002]

2. Description of the Related Art As a conventional speed measuring device of this type,
There are those that measure the speed of the running body from the rotational speed of the propulsion unit of the underwater vehicle, and those that measure the acceleration in the propulsion direction by providing an inertial device and integrate it to obtain the speed. (A) A device for measuring the speed of the running body from the rotational speed of the propulsion device. As shown in FIG. 4, the underwater vehicle 2 rotationally drives a propulsion device 3 such as a screw attached to the tail by a motor 4, and It is sailing by the obtained thrust T generated by the propulsion machine.
A conventional speed calculation process will be described with reference to FIGS.

First, the rotation speed N of the propulsion unit 3 is set to N
^When set to ^* and starting rotation, the propulsion body 2 will have an initial thrust T
= Accelerated at To. As the speed V of the vehicle 2 increases, the thrust T decreases in inverse proportion to the speed V. That is, T∝1 / V (1) On the other hand, the running resistance F increases in proportion to the square of the speed V.
That is, F∝V ² ………… (2) If the acceleration A and mass of the vehicle 2 are M, then the relational expression of A = (TF) / M ………… (3) is established. To do.

When the generated thrust T becomes equal to the running resistance F at the point Po in FIG. 5, then the acceleration A = 0 from the equation (3), and the speed V of the running body 2 becomes constant. T, F, and V at the equilibrium point Po of T and F are T
^When expressed by ^* , F ^* , and V ^* , F ^* = T ^* …………… (4) F ^* = k ₁ ^* V ^{* 2} (k ₁ ^* : proportional constant) …………… (5) T _{^{* = k 2 * N * 2}} : each formula (k ₂ ^* proportional constant) ............ (6) is established. Substituting equations (5) and (6) into (4), k ₁ ^* V ^{* 2} = k ₂ ^* N ^{* 2} ∴V ^* = (k ₂ ^* / k ₁ ^* ) ^1/2 N ^* ……… （7） Here, if we put (k ₂ ^* / k ₁ ^* ) ^1/2 = K ^* ……………… (8), we can express V ^* = K ^* N ^* ………… (9). As shown in equation (9), if we add a suffix (suffix) P to the vehicle speed (called mechanical speed) obtained from the propulsion machine speed, V _P ^* = K ^* N ^* …………… (9 ') The constant K ^* is equal to the thrust T ^* and the resistance F ^*, and the acceleration A =
It is a value when it is 0, that is, when the speed V of the vehicle is equal to the constant speed V _P ^* , and it changes according to the speed V when acceleration / deceleration is present. However, when the mechanical speed V _{P in the} case of acceleration / deceleration is obtained, the nominal value K (for example, K = K ^* is assumed) is used, and it is approximately obtained from V _P ≈KN ………… (10) There is.

(B-1) Platform-type inertial device As shown in FIG. 6A, a horizontal stabilizer (platform) 5
A triaxial accelerometer 6 and a gyroscope (hereinafter referred to as a gyro) 7 are installed on the top. The gyro 7 detects the rotational fluctuation and the earth rate (rotational angular velocity) of the moving body 2, and the servo amplifier 8 outputs signals corresponding to the detected signals.
The servo motor 9 is controlled via the to keep the stable horizontal base 5 horizontal. Acceleration A of the vehicle detected by accelerometer 6 (A
_X , A _Y , A _Z ) are integrated by the calculation unit 10 to obtain the velocity V _I (V
_IX , V _IY , V _IZ ). That is, V _I (V _IX , V _IY , V _IZ ) = ∫A (A _X , A _Y , A _Z ) dt (11) In FIG. 6A, only the fluctuation in the pitch direction is shown. In reality, there is shaking in the three axis directions.

(B-2) Strap-down type inertial device In the platform type, the horizontal stabilizer is held mechanically horizontally and the acceleration above it is detected, whereas in the case of the strap-down type, Using the angular velocities ω (ω _x, ω _y , ω _z ) in the three-axis directions obtained by the gyro 7 directly attached to the aircraft without using the horizontal stabilizer, the arithmetic unit 10 uses the aircraft coordinate system (x, y, z) is the local horizontal coordinate system (X, Y,
Z), a coordinate transformation matrix [C] is obtained, and this matrix [C] is further multiplied by the acceleration A ( _AX , _Ay , _AZ ) in the body coordinate system detected by the accelerometer 6. , V _i (V _IX , V _IY , V _IZ ) in the local horizontal coordinate is obtained by converting the acceleration into the local horizontal coordinate system and integrating the converted acceleration. That is, V _I (V _IX , V _IY , V _IZ ) = ∫ [C] A (A _X , A _y , A _Z ) dt (12) The velocity V _I obtained by the inertial device is the inertial velocity. To distinguish it from the mechanical velocity V _P.

[0007]

In the conventional method for obtaining the mechanical speed V _P from the rotational speed N of the propulsion unit 3, when the speed is changing at the time of starting, as shown in FIG. Since 2 has a mass M, the true speed V rises later than the rise of the propulsion machine speed N, so that V ≠ V _P = KN (K is a nominal value, for example, K = K
^* ), Which is a large calculation error.

In a period in which the propulsive force T and the drag force F are balanced and stable at the final speed, V≈V _P ^* = KN ^* , but K
Originally, it was obtained by tests on a reduced model and may not match the actual model, and there are variations among products. Therefore, a speed calculation error occurs. Further, in the method of obtaining the velocity by the inertial device, the error contained in the accelerometer signal is integrated and the velocity error increases with time.

When the gyro signal ω has an error,
The speed error increases with time because the virtual horizontal plane in the stable horizontal base or the arithmetic unit is not kept true, and the coordinate transformation matrix has an error and the gravity coupling component is integrated. There are drawbacks such as.
An object of the present invention is to eliminate these drawbacks, and to provide a speedometer that obtains speed data with a smaller error, that is, higher accuracy than in the past.

[0010]

[Means for Solving the Problems]

(1) The invention according to claim 1 is an inertial device including a gyroscope, an accelerometer, and an inertial data calculation unit;
It is a speed measuring device for underwater vehicles comprising a speed measuring unit including a speed correcting unit and a running state determining unit. The gyroscope detects the rotational angular velocity ω in the three axis directions. The accelerometer measures acceleration A in the three-axis directions.
Is to detect. The inertia data calculation unit calculates the velocity (referred to as inertial velocity) V _I of the underwater vehicle from the acceleration A and the angular velocity ω and inputs the velocity V _I to the first velocity correction unit, and in each steady traveling period. The corrected inertial velocity V _I ′ input from the first velocity correction unit is used as a reference value to calculate the corrected inertial velocity V _I.

The running state determination unit determines the underwater vehicle from the acceleration A and the angular velocity ω or the acceleration / deceleration signal (dN / dt; N is the rotational speed of the propulsion machine) obtained from the propulsion engine section of the underwater vehicle. The acceleration / deceleration period and the steady running period are discriminated and the discrimination signal is inputted to the first and second speed correction sections. The first speed correction unit outputs the inertial speed V _I input from the inertial data calculation unit to the outside of the device during each acceleration / deceleration period, and the second speed during each steady running period.
The inertial velocity V further corrected by using the corrected mechanical velocity V _P ′ obtained by the velocity correction unit (the velocity obtained from the rotational velocity N is referred to as a mechanical velocity and represented by V _P ).
By calculating the _I ', and inputs the inertial data operation unit.

[0012] The second speed correction unit, during each steady running period
The mechanical speed V_P= KN (K is a coefficient)
Inertial velocity V_IMechanical velocity V corrected using_PPlay ′
It is calculated and output to the outside of the device. (2) In the invention of claim 2, the underwater navigation according to (1) above.
In the velocity measuring device for a running body, the second velocity correction unit is
The first time point of the second (i = 1, 2, 3 ...) Steady state running period
t_i ^*Where the inertial velocity V_I(T_i ^*) And the above times
Rolling speed N (t_i ^*), The corrected coefficient K_i′ = V
_I(T_i ^*) / N (t_i ^*), The coefficient K_i′
Using the corrected mechanical speed in each steady running period
V_P′ = K_iCalculate'N.

(3) In the invention of claim 3, in the speed measuring device for underwater vehicle according to claim (1), the second speed correction unit is the first time point t ₁ of the first steady running period. ^*
, The inertial velocity V _I (t ₁ ^* ) and the rotation velocity N (t ₁
From ^*), corrected coefficient _{K 1 '= V I (t} 1 *) / N
(T ₁ ^* ) is calculated, and the coefficient K ₁ ′ is used in common, and the corrected mechanical speed V _P ′ = in each steady running period.
Calculate K ₁ ′ N.

(4) According to the invention of claim 4, in the speed measuring device for underwater vehicle according to any one of the items (1) to (3), the inertial data calculation unit is provided for the attitude of the vehicle. The angle, azimuth, or position can be calculated and output to the outside.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the case of FIG. 1, which is applied to an automatic piloting system for underwater vehicles. Inertial device 1
Reference numeral 1 has a gyro 7 having three orthogonal axes and an accelerometer 6, and an angular velocity ω and an acceleration A obtained from them are calculated by a calculation unit 10, whereby a posture angle (pitch angle θ, roll angle φ), an azimuth angle ψ, Calculate velocity V _I , position P, etc. Promotion Department 1
2 detects and also adjusts the rotational speed N of the thruster shaft.

The speed measuring unit 13 includes the following 14, 15, 1
Speed data V with high accuracy_TOutput
You can The first speed correction unit 14 is the inertial device 11.
Inertial velocity V obtained_IIs obtained from the propulsion machine rotation speed N.
Speed V_P= Speed corrected for KN (K is the nomisal value)
V_PFurther correction based on ′_IGet ′. Also inertial speed
Degree V_ISwitch SW₂, SW₃Output to. Second speed
The correction unit 15 determines the mechanical speed V _PThe inertial velocity V_IBased on
Correct, V_PWe obtain ′ = K′N. Running state determination unit 16
Is the acceleration A and the angular velocity ω obtained from the inertial device 11.
Is larger than the change dN / dt of the increase / decrease in rotation from the engine section 12.
The judgment signal Sa is output by judging the deceleration period and the steady running period.
Force

The guidance calculator 17 is preset
With signals controlled from the cruise course or from outside
Attitude angle (pitch angle θ, roll angle φ) obtained by self
Position angle ψ, position P, speed V_TGenerates a steering signal Sb
It Controlled by the traveling state determination signal Sa (Fig. 2A)
Switch SW₁To SW ₃Are respectively B and B in FIG.
On / off control is performed as indicated by C and D. Steady running period
Switch SW in between₁Is turned on, and the second speed correction unit 1
Mechanical speed V corrected from 5_P′ Is the first speed correction unit 1
4 is input. In the first speed correction unit 14, V_PRiff
Inertial velocity V input from the inertial device as an offset value_I
Is corrected, and the corrected speed V_I′ Is the inertial data calculation unit
Enter in 10. In the inertia data calculation unit 10, it is corrected
Inertial velocity V_I′ Is used as a reference value for further correction
Inertial velocity V_ITo calculate V_IThe integration error of
I try not to increase with time.

During the acceleration / deceleration period, the switch SW ₂ is turned on, and the inertia speed V _I (t) is input from the first speed correction unit 14 to the second speed correction unit 15. In the second speed correction unit 15, the speed V _I (t) is divided by the rotation speed N (t) input from the rotation speed detection unit 12a, and the time t = when the running state determination signal Sa falls from ON to OFF. Quotient of t ^* V _I (t ^* )
/ N (t ^*) 'as a, the constant K in the steady running period' constant K that has been corrected velocity V _P of the speed corrected using the '
(T) = K′N (t) is calculated and input to the guidance calculation unit 17 through the speed correction unit 14 and the contact bc of the switch SW ₃ .

The switch SW ₃ is switched to the contact a side during the acceleration / deceleration period, and the inertial velocity V _I is input to the guidance calculator 17 as the output velocity V _T of the measuring device. It should be noted that the inertia data calculation unit 10 and the first speed correction unit 14 can be combined into one. In that case, a state estimation filter such as a Kalman filter may be used for the combined portion to correct not only the velocity data but also the data such as the attitude angle, the azimuth angle, and the position.

The first speed correction unit 14 outputs the inertial speed V _I to the outside during the acceleration / deceleration period in synchronization with the determination signal Sa, and the second speed correction unit 15 synchronizes with the determination signal Sa to perform steady running. Since the corrected mechanical speed V _P ′ can be output to the outside during the period, the switch SW ₃ may be omitted. In addition, the first and second speed correction units 14 and 15 use the determination signal S
Based on a, the speed V is calculated during the period required by the other side.
_I or V _P ′ can be supplied, or speed data can always be supplied and the data can be fetched in a necessary period by the side using the switch SW ₁ ,
SW ₂ may be omitted.

Next, the operation of FIG.
Let us explain this in more detail by taking the time-varying characteristic as an example. When starting, the inertial speed of the propulsion axis by the inertial device 11
V_IIs correct and V _T= V_IIs output to the outside. Elapsed time from start or fluctuation of acceleration
Or acceleration / deceleration signal dN / dt obtained from the propulsion engine unit 12
Time t when it is determined that the speed has become constant due to ₁ ^*Then V_P(T₁ ^*) = KN (t₁ ^*) …………… (13) V found from_P(T₁ ^*), Which is more accurate than)
_I(T₁ ^*) Is correct, V_I(T₁ ^*) = K₁′ N (t₁ ^*) ≡ V_P′ (T₁ ^*) ... (14), corrected nominal value K₁′ K₁′ = V_I(T₁ ^*) / N (t₁ ^*) …………… (15) is requested.

After that, during steady-state running with a small fluctuation of the rotation speed, V _P ′ = K ₁ ′ N (16) obtained from the corrected K ₁ ′ and the rotation speed N of the propulsion machine is correct, and This is output (V _T = V _P ′). Further, since the error of the velocity V _I obtained from the inertial device increases until then, V _I ′ corrected by using V _P ′ as a reference value is input to the inertial data calculation unit 10.

If acceleration / deceleration has occurred, V _I is correct and V _T = V _I is output. At time t ₂ ^* is determined that the steady driving Second, similarly to ^{_{V P (t 2 *) =}} KN (t 2 *) obtained from _{............... (17) V P (t} 2 *) More accurate than V _I (t ₂
^* ) Is correct, and the corrected nominal value K is set by setting V _I (t ₂ ^* ) = K ₂ ′ N (t ₂ ^* ) = _VP ′ (t ₂ ^* ) ... (18) ₂ ′ K ₂ ′ = V _I (t ₂ ^* ) / N (t ₂ ^* ) …………… (19) is calculated.

[0024] However, the coefficient K 'is the dimension of Kohashikarada 2 and propulsion units 3, the shape does not change, it is considered that the time constant, in (15) the nominal value was corrected calculated from the equation K _1' Can be omitted and the calculation can be simplified. (A) The second speed correction unit 15 obtains V _P ′ = K ₂ ′ N obtained from (a) the corrected K ₂ ′ and the propulsion machine rotation speed N during the second steady running in which the rotation speed fluctuation is small. ……………… Assuming that (20) is correct, this is output (V _T = V _P ′).

(B) Alternatively, the corrected nominal value K ₁ ′ obtained in step ( ₁ ) is used every time to obtain and output V _P ′ = K ₁ ′ N (21). Also, the velocity V obtained from the inertial device
_{Since the} error of I increases during the steady running period, the first speed correction unit 14 corrects V _I ′ corrected using V _P ′ as a reference value.
Is input to the inertial data calculation unit 10.

[0026]

EFFECT OF THE INVENTION Conventionally, since the mechanical speed V _P = KN calculated from the rotational speed N of the propulsion machine is used as the speed output V _T , the true speed V of the running body 2 is its own during acceleration / deceleration. Due to the existence of the mass, a large calculation error occurred because it was considerably delayed from the change of the propulsion machine rotation speed N. However, in the present invention, since the detected speed V _I of the inertial device 11 is the speed output V _T , the calculation error is caused. Significantly reduced.

Conventionally, the velocity output V _T during steady running was also obtained from V _P = KN, but originally the constant K was obtained by testing a reduced model, and there was an error with the actual machine, Furthermore, there are variations for each of the vehicles. For these reasons, there was a considerable speed calculation error even during steady driving. However, in the present invention, the acceleration signal A and the angular velocity ω detected by the inertial device are distinguished from the acceleration / deceleration signal dN / dt obtained from the propulsion engine unit 12 during acceleration / deceleration and during steady running, and the former is changed to the latter. Point t when switching
^* The inertial velocity V _I (t ^*) and the rotation speed N (t ^*) from the corrected coefficients K 'determined ^{_{= V I (t *) /}} N a (t ^*) for each Wataru Hashikarada, the K' Is used to determine the speed output V _T = V _P ′ = K′N during steady running. Therefore, the calculation error caused by the error of the conventional constant K itself can be eliminated.

In the conventional method for obtaining the velocity by the inertial device, the error contained in the accelerometer output and the gyro output is also integrated, so that there is a drawback that the integration error increases with time. Since the inertial velocity V _I is used only during acceleration / deceleration for a relatively short time, the integration error is considerably reduced. Moreover, the inertial speed V _I is corrected by the corrected speed output V _T =
Since the inertial device performs the correction calculation so as to match the corrected inertial velocity V _I ′ with V _P ′ = K′N as the reference value, the integration error that increases with time as in the conventional case is removed. Is in a state. Therefore, the inertial velocity V _I can be used as the velocity output V _T at any time during acceleration / deceleration, and highly accurate data without the influence of the previous integration error can be obtained.

[Brief description of drawings]

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

FIG. 2 is an operation waveform diagram of a main part of FIG.

FIG. 3 is a diagram showing a temporal change in the detection speed of a main part in FIG.

FIG. 4 is a principle explanatory diagram of thrust T and resistance F acting on the underwater vehicle.

5 is a diagram showing a change characteristic of the thrust T and the resistance F of FIG. 4 with respect to a traveling speed V.

FIG. 6 is a principle explanatory view of a conventional example in which an inertial device is mounted on an underwater vehicle to detect speed.

FIG. 7 is a diagram showing an example of changes in the propulsion machine rotation speed N and the true speed V of the running body with respect to time t.

Claims (4)

[Claims] 1. An underwater vehicle speed including an inertial device including a gyroscope, an accelerometer, and an inertial data calculation unit, and a speed measurement unit including first and second speed correction units and a running state determination unit. A measuring device, wherein the gyroscope detects a rotational angular velocity ω in three axis directions, the accelerometer detects an acceleration A in the three axis directions, and the inertia data calculation unit , V of the underwater vehicle (referred to as inertial velocity) V _I is calculated from the acceleration A and the angular velocity ω and input to the first velocity correction unit, and the first velocity correction is performed in each steady traveling period. The corrected inertial velocity V _I ′ input from the section is used as a reference value to calculate the corrected inertial velocity V _{I. The} traveling state determination unit calculates the acceleration A and the angular velocity ω or the underwater vehicle. Guess Acceleration and deceleration signal obtained by the engine unit (dN
/ Dt; N is the rotational speed of the propulsion unit) and determines the acceleration / deceleration period of the underwater vehicle and the steady running period, and inputs the determination signal to the first and second speed correction units, The first speed correction unit outputs the inertial speed V _I input from the inertial data calculation unit to the outside of the device during each acceleration / deceleration period, and the correction obtained by the second speed correction unit during each steady running period. Mechanical speed V _P ′ (speed obtained from the rotation speed N is called mechanical speed and is represented by V _P ).
Is further used as a reference value to calculate an inertial speed V _I ′, which is input to the inertial data calculation unit. The second speed correction unit, in each steady traveling period, mechanical speed V _P = Let KN (K is a coefficient) be the inertial velocity V
_An underwater vehicle speed measuring device, characterized in that it calculates a mechanical speed V _P ′ corrected using _I and outputs it to the outside of the device. 2. The underwater vehicle speed measurement device according to claim 1, wherein the second speed correction unit is i-th (i = 1,
2, 3 ...) At the first time point t _i ^* of the steady traveling period, the inertial speed V _I (t _i ^* ) and the rotational speed N (t
_{From i} ^* ), the corrected coefficient K _i ′ = V _I (t _i ^* ) / N
(T _i ^* ) is calculated, and the corrected mechanical speed V _P ′ = K _i ′ N in each steady running period is calculated using the coefficient K _i ′.
Is calculated. 3. The underwater vehicle speed measuring device according to claim 1, wherein the second speed correction unit is configured to inertial speed V _I (t ₁₎ at a first time point t ₁ ^* of a first steady running period.
^* ) And the rotational speed N (t ₁ ^* ) corrected coefficient K ₁ ′ =
V _I (t ₁ ^* ) / N (t ₁ ^* ) is obtained and its coefficient K ₁ ′
Is commonly used to calculate the corrected mechanical speed V _P ′ = K ₁ ′ N in each steady running period. 4. The underwater vehicle speed measuring device according to claim 1, wherein the inertial data calculation unit calculates an attitude angle, an azimuth angle, or a position of the vehicle and outputs the data to the outside. It is characterized by being able to output.