JP2733598B2 - Underwater vehicle speed measurement device - Google Patents

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 a method for reducing measurement errors, that is, improving accuracy.

[0002]

2. Description of the Related Art Conventional speed measuring devices of this type include:
There are a type that measures the speed of a marine vehicle based on the rotation speed of a propulsion unit of an underwater vehicle, and a type that measures the acceleration in the direction of propulsion by providing an inertial device and calculates the speed by integrating the acceleration. (A) Apparatus for measuring the speed of the running vehicle from the rotation speed of the propulsion unit As shown in FIG. 4, the underwater vehicle 2 drives a propulsion unit 3 such as a screw attached to its tail by a motor 4, and The ship is sailing with the obtained thrust T generated by the thruster.
A conventional speed calculation process will be described with reference to FIGS.

First, the rotation speed N of the propulsion device 3 is set to N
^{* When} the engine starts rotating, the hull 2 has an initial thrust T
= 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) Assuming that the acceleration A and mass of the vehicle 2 are M, the relational expression of A = (T−F) / M (3) holds. I do.

When the generated thrust T and the running resistance F are equal at the point Po in FIG. 5, the acceleration A = 0 at that time according to the equation (3), and the speed V of the running body 2 is constant. T, F, and V at the equilibrium point Po between T and F are represented by T
^*, F ^*, is represented by ^{V *, F * = T *} ............... (4) F * = k 1 * V * 2 (k 1 *: proportional constant) ............... (5) T ^* = K ₂ ^* N ^{* 2} (k ₂ ^* : proportionality constant) Each equation of (6) holds. (5), (6) by substituting equation in the ^{_{(4), k 1 * V}} * 2 = k 2 * N * 2 ∴ V * = (k 2 * / k 1 *) 1/2 N * ...... ……… (7) Here, if (k ₂ ^* / k ₁ ^* ) ^1/2 = K ^* ... (8), then V ^* = K ^* N ^* ... (9) can be expressed. If a subscript (suffix) P is added to the speed of the sailing body (referred to as mechanical speed) determined from the rotation speed of the propulsion unit as in equation (9), V _P ^* = K ^* N ^* …………… (9 ') The constant K ^* is such that the thrust T ^* and the resistance F ^* are balanced and the acceleration A =
The value is 0 when the vehicle speed V is equal to the constant speed _VP ^* , and changes according to the speed V when there is acceleration / deceleration. However, when obtaining the machine speed V _P of when there is acceleration or deceleration by using the nominal value K (e.g. K = K ^* assuming), with approximately determined from V _P ≒ KN ............... (10) I have.

(B-1) Platform type inertial device As shown in FIG. 6A, a horizontal stabilizer (platform) 5
A three-axis accelerometer 6 and a gyroscope (hereinafter referred to as a gyroscope) 7 are provided on the top. The gyro 7 detects the rotation fluctuation and the earth rate (rotational angular velocity) of the marine vessel 2 and uses a signal corresponding to the detected signal to generate a servo amplifier 8.
To control the servo motor 9 to keep the stable horizontal base 5 horizontal. The acceleration A of the hull body detected by the accelerometer 6 (A
_X , A _Y , A _Z ) are integrated by the calculation unit 10 and the speed V _I (V
_IX , V _IY , V _IZ ). _{That, V I (V IX, V} IY, V IZ) = ∫A (A X, A Y, A Z) dt ............... (11) shows only Figure 6A the upset in the pitch direction, Actually, there is a three-axis sway.

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

[0007]

In a manner to obtain the mechanical speed V _P from the rotational speed N of a conventional propulsion apparatus 3 THE INVENTION An object will to solve the above-In the case where the rate of such at the start has changed, as shown in FIG. 7, Kosokutai 2 has a mass M, and the true speed V rises later than the rise of the propulsion unit rotation speed N, so that V ≠ V _P = KN (K is a nominal value, for example, K = K
^* ), Resulting in a large calculation error.

In a period in which the propulsive force T and the drag F are balanced and stable at the final speed, V ≒ V _P ^* = KN ^*.
Is originally obtained by a test with 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 speed by the inertial device, the error included in the accelerometer signal is integrated, and the speed error increases with time.

When the gyro signal ω has an error,
The fact that the virtual horizontal plane in the stable horizontal platform or the operation unit is not held true true, and that the coordinate transformation matrix has an error and integrates the gravitational coupling component causes the speed error to increase with time. There are drawbacks.
SUMMARY OF THE INVENTION An object of the present invention is to provide a speedometer which eliminates these drawbacks and obtains speed data with a smaller error, that is, with higher accuracy than in the prior art.

[0010]

[Means for Solving the Problems]

(1) The invention according to claim 1 is an inertial device comprising a gyroscope, an accelerometer, and an inertial data operation unit, and first and second inertial devices.
This is a speed measuring device for an underwater vehicle, comprising a speed correcting unit and a speed measuring unit including a running state determining unit. The gyroscope detects a rotational angular velocity ω in three axial directions. The accelerometer calculates the acceleration A in the three axial directions.
Is to be detected. The inertial data operation unit, said (referred to as inertial velocity) from the acceleration A and the angular velocity ω speed of underwater vehicle by calculating the V _I, and inputs to the first speed correcting section in each steady running period is for calculating the inertial velocity V _I in which the first speed correcting unit inertial velocity is corrected is input from the V _I 'is further corrected as a reference value.

[0011] The running state determination unit determines the acceleration A and the angular velocity ω or the acceleration / deceleration signal (dN / dt; N is the rotation speed of the propulsion unit) obtained by the propulsion engine unit of the underwater vehicle. The acceleration / deceleration period and the steady running period are determined, and the determination signal is input to the first and second speed correction units. It said first speed correcting unit outputs the inertial velocity V _I of each deceleration period is input from the inertial data arithmetic unit to the outside of the apparatus, in each normal running period, the second
The inertia speed V further corrected using the corrected mechanical speed V _P ′ obtained by the speed correction unit (the speed obtained from the rotation speed N is referred to as mechanical speed and expressed as V _P ) as a reference value.
_I ′ is calculated and input to the inertial data calculation unit.

[0012] The second speed correction unit is provided for each steady running period.
The mechanical speed V_P= KN (K is a coefficient)
Inertia velocity V_IMechanical velocity V corrected using_P′
And outputs it to the outside of the device. (2) According to the second aspect of the invention, the underwater navigation according to the above (1) is provided.
In the speed measurement device for a running body, the second speed correction unit may include i
First time point of the (i = 1,2,3 ...) steady running period
t_i ^*In the above, the inertial velocity V_I(T_i ^*) And said times
Rolling speed N (t_i ^*) From the corrected coefficient K_i'= V
_I(T_i ^*) / N (t_i ^*) And its coefficient K_i′
Using the corrected mechanical speed during each steady driving period
V_P'= K_i'N.

(3) In the invention according to claim 3, in the underwater vehicle speed measuring device according to the above (1), the second speed correction unit is configured to determine the first time point t ₁ of the first steady running period. ^*
, The inertial speed V _I (t ₁ ^* ) and the rotation speed N (t ₁
^* ), The corrected coefficient K ₁ ′ = V _I (t ₁ ^* ) / N
(T ₁ ^* ), and using the coefficient K ₁ ′ in common, the corrected mechanical speed _VP ′ =
Calculate K ₁ 'N.

(4) In the invention according to claim 4, in the underwater vehicle speed measurement apparatus according to any one of the above (1) to (3), the inertial data calculation unit includes a posture of the vehicle. The angle, azimuth or position can be calculated and output to the outside.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. 1 in which an embodiment of the present invention is applied to an underwater vehicle autopilot. Inertial device 1
1 has a gyro 7 and an accelerometer 6 of three orthogonal axes, and an angular velocity ω and an acceleration A obtained from these are calculated by an arithmetic unit 10 so that an attitude angle (pitch angle θ, roll angle φ), an azimuth angle ψ, The speed V _I , the position P, etc. are calculated. Promotion Agency 1
2 detects and adjusts the rotational speed N of the thruster shaft.

The speed measuring unit 13 has the following 14, 15, 1
6 and high-accuracy speed data V_TOutput
Can be The first speed correction unit 14 is connected to the inertial device 11
Inertia velocity V obtained_IIs obtained from the mechanical
Speed V_P= KN (K is the nominal value) corrected speed
V_P'Is further corrected based on_I'. Also inertial speed
Degree V_ISwitch SW_Two, SW_ThreeOutput to 2nd speed
The correction unit 15 calculates the mechanical speed V _PIs the inertial velocity V_IBased on
Correct, V_P'= K'N. Running state determination unit 16
Is the acceleration A and angular velocity ω obtained from the inertial device 11
Is greater than the change dN / dt in the increase / decrease of rotation from the engine unit 12.
A determination signal Sa is output after determining the deceleration period and the steady driving period.
Power.

The guidance calculation unit 17 is set in advance.
On the course or signals controlled from the outside
Attitude angle (pitch angle θ, roll angle φ), direction
Angle ψ, position P, speed V_TGenerates a steering signal Sb
You. It is controlled by the traveling state determination signal Sa (FIG. 2A).
And switch SW₁Or SW _ThreeAre B in FIG. 2, respectively.
On / off control is performed as shown in C and D. Steady running period
Switch SW 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_P′ Riff
Inertial velocity V input from inertial device as reference value_I
Is corrected, and the corrected speed V_I′ Is the inertia data operation unit
Enter 10 In the inertia data calculation unit 10, the corrected
Inertia velocity V_I'As a reference value,
Inertia velocity V_ITo calculate V_IThe integration error of
It does not increase over 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. The second speed correction unit 15 divides the speed V _I (t) by the rotation speed N (t) input from the rotation speed detection unit 12a, and the time t = when the traveling state determination signal Sa falls from on to off. t ^* of the quotient V _I (t ^*)
/ N (t ^* ) is obtained as a corrected constant K ′, and the speed V _P ′ whose speed is corrected using this constant K ′ during the steady running period.
(T) = seeking K'N (t), and inputs to the induction calculation unit 17 through the contact b-c of the speed correcting section 14 and the switch SW _3.

The switch SW ₃ is the acceleration and deceleration time is switched to the contact a side, inertial velocity V _I is input to the induction calculating section 17 as the output speed V _T of the measuring device. In addition, the inertia data calculation unit 10 and the first speed correction unit 14 can be combined into one. In this case, not only velocity data but also data such as an attitude angle, an azimuth angle, and a position can be corrected by using a state estimation filter such as a Kalman filter in the united portion.

[0020] The first speed correcting section 14 in synchronization with the judgment signal Sa, and outputs the inertial velocity V _I outside the acceleration or deceleration period, and the second speed correcting section 15 in synchronization with the judgment signal Sa, steady running the period, the corrected mechanical velocity V _P 'can be output to the outside, it may be omitted switch SW _3. The first and second speed correction units 14 and 15 output the determination signal S
a during the period required by the other party based on the
Or so as to supply the _I or V _P ', or constantly supplies the speed data, so that data can be fetched appropriate period required side to use, the switch SW _1,
The SW ₂ may be omitted.

Next, the operation of FIG. 1 will be described with reference to FIG.
This will be described in more detail with reference to a temporal change characteristic. At the time of start, the inertial speed in the direction of the propulsion axis by the inertial device 11
V_IIs correct and V _T= V_IIs output to the outside. Time elapsed since start or fluctuation of acceleration
Or the acceleration / deceleration signal dN / dt obtained from the propulsion engine unit 12.
T when it is determined that the speed is constant ₁ ^*And V_P(T₁ ^*) = KN (t₁ ^*) ……………………………………… (13)_P(T₁ ^*Inertia velocity V with higher accuracy than
_I(T₁ ^*) Is correct and V_I(T₁ ^*) = K₁'N (t₁ ^*) ≡V_P'(T₁ ^*) ... (14) and corrected nominal value K₁'K₁'= V_I(T₁ ^*) / N (t₁ ^*) …………… (15)

Hereafter, it is assumed that V _P ′ = K ₁ ′ N obtained from the corrected K ₁ ′ and the propulsion unit rotation speed N during steady running with small fluctuations in the rotation speed. This is output ( _VT = _VP '). Further, since the error of the speed V _I obtained from the inertial device increases before that, V _I ′ corrected with V _P ′ as a reference value is input to the inertia data calculation unit 10.

If acceleration or deceleration occurs, V _{I is determined} to be 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 *) V _I (t ₂
^*) As a ^{_{correct, V I (t 2 *)}} = K 2 'N (t 2 *) = V P' (t 2 *) at the ............... (18), corrected nominal value K _{2 'K 2' = V I} (t 2 *) / N (t 2 *) Request ............... (19).

However, the coefficient K 'is considered to be constant over time since the size and shape of the hull 2 and the propulsion unit 3 do not change, so the corrected nominal value K ₁ ' obtained by the equation (15) is used. Can be omitted, and the processing can be simplified to simplify the operation. (A) The second speed correction unit 15 is configured to provide, during the second steady running with little rotation speed fluctuation, (A) V _P ′ = K ₂ ′ N obtained from the corrected K ₂ ′ and the propulsion unit rotation speed N. ... (20) is assumed to be correct and is output (V _T = V _P ′).

(B) Alternatively, by using the corrected nominal value K ₁ 'obtained every time, V _P ' = K ₁ 'N (21) is obtained and output. 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 ′ using V _P ′ as a reference value.
Is input to the inertial data calculation unit 10.

[0026]

As conventionally velocity output V _T, according to the present invention, at the time of acceleration and deceleration so have used mechanical speed V _P = KN which was calculated from the rotational speed N of the propulsion unit, the true velocity V of Kohashikarada 2 is itself a large calculation error to significantly lag the changes in the propulsion speed N by the presence of the mass occurs, so this during acceleration and deceleration is invention has a detection speed V _I a velocity output V _T of the inertial device 11, is computed error Significantly reduced.

Conventionally, the speed output V _T at the time of steady running was also obtained from V _P = KN. However, the constant K was originally obtained by testing a reduced model, and there was an error with the actual machine. Further, there is a variation for each vehicle. For these reasons, there was considerable speed calculation error even during steady driving. However, according to the present invention, the acceleration signal A and the angular velocity ω detected by the inertial device determine whether the vehicle is accelerating or decelerating and when the vehicle is in a steady running state based on the acceleration / deceleration signal dN / dt obtained from the propulsion engine unit 12. Switching time t
^The coefficient K ′ = V _I (t ^* ) / N (t ^* ) corrected from the inertia speed V _I (t ^* ) and the rotation speed N (t ^* ) of ^* is obtained for each cruising vehicle. Is used to determine the speed output V _T = V _P '= K'N during steady running. Therefore, it is possible to eliminate the calculation error caused by the error of the conventional constant K itself.

In the conventional method for obtaining the speed by the inertial device, the errors included in the accelerometer output and the gyro output are integrated together, so that there is a disadvantage that the integration error increases with time. Since the inertial velocity V _I is used only during the acceleration / deceleration in a very short time, the integration error is considerably reduced. In addition, the inertial speed V _I is the corrected speed output V _T = during a relatively long period of steady running.
Since the inertial device performs the correction operation so as to coincide with the corrected inertial velocity V _I ′ using V _P ′ = K′N as a reference value, the conventional integration error that increases with time has been removed. In state. Therefore, it is possible to use the inertial velocity V _I at any time if during acceleration and deceleration to the velocity output V _T, yet is highly affected without the precision of previous integration error data obtained.

[Brief description of the 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 a detection speed of a main part in FIG. 1;

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

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

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

FIG. 7 is a diagram illustrating an example of a change in the rotation speed N of the propulsion device and the true speed V of the traveling vehicle with respect to time t.

Claims (4)

(57) [Claims] 1. An underwater vehicle speed comprising 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 traveling state determination unit. A measuring device, wherein the gyroscope detects a rotational angular velocity ω in three axial directions; the accelerometer detects the acceleration A in the three axial directions; the (referred to as inertial velocity) from the acceleration a and the angular velocity ω speed of underwater vehicle by calculating the V _I, and inputs to the first speed correcting section in each normal running period, the first speed correction The corrected inertia speed V _I ′ input from the section is used as a reference value to calculate a further corrected inertia speed V _I , wherein the traveling state determination unit is configured to calculate the acceleration A and the angular velocity ω or the underwater vehicle. Push Acceleration and deceleration signal obtained by the engine unit (dN
/ Dt; N is the rotation speed of the propulsion unit) and determines the acceleration / deceleration period and the steady traveling period of the underwater vehicle, and inputs the determination signal to the first and second speed correction units. said first speed correction unit said inertial velocity V _I input from the inertial data arithmetic unit outputs to the outside of the apparatus at each deceleration period, each normal running period, obtained by the second speed correcting section corrects Mechanical speed V _P ′ (the speed obtained from the rotation speed N is referred to as mechanical speed and is represented by V _P )
Is used as a reference value to calculate the inertia speed V _I ′, which is input to the inertia data calculation unit. The second speed correction unit calculates the mechanical speed V _P = KN (K is a coefficient) is calculated by
_A speed measuring device for underwater vehicles, wherein the device 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 an ith (i = 1,
2,3 ...) at the first time point t _i ^* of steady running period, the inertial velocity V _I (t _i ^*) and the rotation speed N (t
_i ^* ), the corrected coefficient K _i ′ = V _I (t _i ^* ) / N
(T _i ^* ) is obtained, 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 measurement device according to claim 1, wherein the second speed correction unit is configured to control the inertial speed V _I (t ₁₎ at a first time point t ₁ ^* of a first steady running period.
^* ) And the coefficient K ₁ ′ = corrected from the rotation speed N (t ₁ ^* )
V _I (t ₁ ^* ) / N (t ₁ ^* ) is obtained and its coefficient K ₁ ′
Using in common, characterized by calculating the corrected mechanical velocity V _P '= K _1' N in each steady running period. 4. The underwater vehicle speed measurement 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 externally calculates the attitude angle, the azimuth angle, or the position of the vehicle. It can be output.