DE2818202A1 - NAVIGATION DEVICE FOR LAND, AIR OR SEA VEHICLES - Google Patents

Description

Patent attorneys
DIPL.-PHYS. JÜRGEN WEISSE DIPL.-CHEM. DR. RUDOLF WOLGAST

D 562o Velbert 11 - Langenberg, Bökenbusch 41 P.O. Box 11 o3 86 Telephone (o2127) 4ol9 Telex 8516895

Patent registration Bodenseewerk Geräteechnik GmbH, D-7770 Überlingen / Bodensee

Navigation device for land, air or sea vehicles

The invention relates to a navigation device for land, air or sea vehicles, containing :.

an inertia measuring unit with rotationally sensitive inertia sensors, which react to rotational movements around axles fixed to the vehicle respond, and accelerometers that respond to linear accelerations along axles fixed to the vehicle, Speed sensors, which are based on the speed components of the vehicle in the direction of predetermined address fixed vehicle axles, and a Transformationpar ameter computer on which the signals from the inertia measuring unit are switched on and the calculation of transformation parameters for the transformation of vector components of a vehicle-fixed coordinate system is set up in a fixed-earth coordinate system.

A navigation device has the task of the position of the vehicle in a suitable earth-fixed coordinate system to specify.

909845/008

There are inertial navigation devices are known in which a The platform is gimbaled and stabilized with respect to the vehicle by gyroscopes and carries accelerometers Address linear accelerations along platform-fixed axes. By integrating the acceleration signals twice Receive signals that reflect the distance covered in the various directions with respect to a reference point. Since the Gyroscopic endeavors to stabilize the platform in inertial space, while usually the platform with an axis perpendicular is to be kept aligned to the earth's surface, the output signals are fed back to the platform for post-rotation (Richard H. Parvin "Inertial Navigation" D. van Nostrand Comp. Inc, 1962). Such inertial navigation devices with gimbals suspended and stabilized and tracked to the surface of the earth Platform are extremely complex. The speed and speed obtained by integrating the acceleration signals Position signals are subject to certain characteristic errors.

It is also known to arrange the accelerometers not on a stabilized platform but fixed to the vehicle. Changes in the position of the vehicle are recorded by turning gyros, which are used to calculate transformation parameters that describe the mutual position of the measuring system fixed to the vehicle and the fixed reference system. In a coordinate transformation computer the acceleration signals measured in the vehicle-fixed coordinate system are transferred to the Earth-fixed coordinate system transformed. Speed and position signals can then be integrated into one Earth-based coordinate system can be obtained. Such devices are referred to as "strapdown" inertial navigation devices (V. Wetzig "To determine the direction reference in strapdown navigation systems" DFVLR, IFF, 1974)

909845/0089

It is also in the not pre-published, older one Patent application P 27 41 274.4-52 proposed a device for automatically determining the north direction in a land vehicle has been, in which a biaxial, electrically constrained gyroscope with its spin axis is essentially vertical is arranged and on its input axes perpendicular to each other and to the twist axis each have a position tap and one Has torque generator. The signal of each position tap assigned to an input axis is crossed over to the torque generator of the other input axis. The signals fed to the two torque generators are simultaneous switched to a north deviation calculator, which calculates the deviation of a device-fixed from the ratio of the signals Supplies a signal reproducing the reference direction from north. In a preferred embodiment of the patent application P 27 41 274.4-52 a pair of accelerometers is connected to the gyro unit, the axes of sensitivity of which are perpendicular to one another stand and parallel to the two input axes which a pair of error signals according to the deviation of the Deliver gyroscopic axis from the vertical. From the signals from the north deviation calculator and the accelerometer v / ground the lag angles of the KCeiseleinhe'it and in particular the Normal deviation calculated. When used in a vehicle, the accelerometers are fixed to the vehicle and the The housing of the gyro can be pivoted through 90 ° about one of the input axes of the gyro. A calculator calculates from the Accelerometer supplied information about the position of the vehicle to the horizontal and that supplied by the gyro Angular velocities around the fixed vehicle entry axes of the gyroscope determine the true course.

However, the device after this older registration does not provide the course with the position of the vehicle.

909845/0080

There is also a device for navigation of land vehicles known (DE-OS 25 45 025), which a north-seeking Meridian gyro to determine the north direction, a free gyro that can be aligned with the meridian gyro as a course reference device, a speed sensor (tachometer) for generating a signal proportional to the vehicle speed and has a computer that provides the position of the vehicle from the course and speed. Determining the position of the Vehicle from the signals of a speed sensor is also with certain, for this navigation method afflicted with characteristic errors.

The invention is based on the object of creating a navigation device for land, air or sea vehicles, which is at simple construction allows an exact determination of the position.

According to the invention, this object is achieved by a correction signal generator, to which transformation parameters are switched from the transformation parameter computer and their Output signals the proportions of the accelerations acting on the accelerometers caused by gravity and superimposed on the signals of the accelerometer to form translational acceleration signals are, integrators on which the translational acceleration signals are switched on and which deliver inertial speed signals, an optimal filter to which the inertial Speed signals and the signals of the speed sensors are switched on and which are taken into account these signals deliver optimized speed signals based on vehicle-fixed coordinates, a coordinate transformation computer, which the optimal speed signals and the transformation parameters from the transformation parameter calculator are supplied and to transform these speed signals into transformed speed signals is set up, which are related to a fixed-earth coordinate system, and a position computer to which the transformed Speed signals are switched on and which is set up to form position signals which the Position of the vehicle wi ^ igrg ^ bgijy.g q g g

-JV-

According to the invention, speed signals are once made from the signals according to the principles of inertial navigation the accelerometer won. The inertial sensors of the inertial measuring unit that respond to rotary motion allow the compensation of the gravity-related components in the accelerometer signals, so that without Gyro-stabilized platform signals that reflect the pure translational accelerations in the vehicle Display coordinates. From this, "inertial" speed signals can be generated through integration over time. Further speed signals, also in fixed vehicle coordinates, are supplied by the speed sensors, so that the speed information redundant, namely once by the inertial speed signals and to is available to others through the speed sensors. Each of these speed signals is for the relevant one Measurement processes are subject to characteristic errors, so that the speed signals usually differ from one another will. The inertial speed signal tends to errors increasing over time, while with most speed sensors ζextinvariant zero point and scale factor errors appear. The two types of speed signals are applied to a matched filter, which supplies estimated values, which takes into account the different error processes and the represents the most likely values for the velocity components.

Such optimal filters and their design are known per se (A. Gelb "Applied Optimal Estimation" MIT Press, London 1974 or U. Krogmann "Das Kaiman-Filter" in "Internationale Electronic Rundschau "1974 issue 3 pages 45-49 and issue 4 pages 71-76).

9098A5 / 008Ö

The optimized ones obtained in this way in the vehicle-fixed coordinate system Speed signals are then converted into a by the coordinate transformation computer by means of the transformation parameters, which in this case fulfill their second function Earth-based coordinate system transformed. The position is derived from the speed components transformed in this way certainly.

Advantageously, transformation parameter correction signals are from the optimal filter switched to the transformation parameter calculator.

Furthermore, it is possible and advantageous for the optimal filter to receive speed correction signals for correction the output signals of the speed sensors can be generated in order to at least partially compensate for the typical error components mentioned.

The inertia measuring unit can, in the manner of patent application P 27 41 274.4-52, with a two-axis gyro and two Accelerometers be constructed, with a rotational accelerometer as a further rotationally sensitive inertia sensor is provided with a downstream integrator whose input axis is parallel to the spin axis of the gyro in its pivoted position.

Instead of two uniaxial accelerometers, a biaxial accelerometer can also be used. Instead of A two-axis gyro can also be provided with two single-axis turning gyros. Finally, can also take place a biaxial gyro, two uniaxial rotational accelerometers with downstream integrators can be used.

09845 / QQ8i

* \ 28182Ü2

A Doppler radar can be used as speed sensors in aviation, a sonar log in seafaring and land vehicles a laser or electromechanical position or speed sensor can be provided.

The invention is explained in more detail below using an exemplary embodiment with reference to the accompanying drawings:

Fig. 1 is a perspective view and

shows schematically a vehicle and the arrangement of the various sensors on this vehicle.

Fig. 2 shows in perspective the inertia measuring unit when determining the north direction.

Fig. 3 shows the arrangement and circuit of the

two-axis gyro in the inertial measuring unit of FIG.

4 shows the inertia measuring unit in its "navigation" operating position.

Fig. 5 is a circuit diagram showing signal processing for navigation.

Fig. 6 shows as a block diagram an optimal filter,

as used in the arrangement of FIG.

In Fig. 1, 10 denotes a vehicle. Speed sensors 12, 14 are attached to the vehicle 10, for example electromechanical speed sensors, which the vehicle speed in the direction of the vehicle longitudinal

F F

axis χ and the vehicle transverse axis y. On the vehicle an inertia measuring unit 16 is also attached. the

909845/0089

Inertia measuring unit 16 contained in a frame (housing) a two-axis gyro 20 which can be pivoted relative to the frame 18 about an axis 22 parallel to the transverse axis of the vehicle is. This pivoting takes place by means of a motor 24 and is monitored by an angle sensor 26. In the The position of the gyro 20 shown is the spin axis parallel to the vehicle longitudinal axis χ. The two entrance axes

of the gyro 20 are parallel to the vehicle transverse axis y and to

F.
Vehicle vertical axis ζ. Two accelerometers 28 and 30 are also attached to the frame 18 of the inertia measuring unit. The input axis of the accelerometer 28 is parallel to the vehicle longitudinal axis χ and the input axis of the acceleration

F gungsmesser 30 is parallel to the vehicle transverse axis y. The inertia measuring unit 16 further includes a rotational accelerometer 32, the input axis of which is parallel to the longitudinal

axis χ and the twist axis of the gyro 20 is. The rotational accelerometer 32 thus measures rotational accelerations around the

F.
Vehicle longitudinal axis χ.

The gyro 20 with its housing can be rotated by 90 between the position shown in FIG Can be pivoted position, which is shown in FIG. This pivoting takes place by means of the servomotor 24, the can be controlled via servo electronics controlled by the angle sensor 26. Depending on the position of a switch 36 controls the servo electronics in the position shown in FIG. 2 or in the position of FIG. 4.

In the position of FIG. 2, the gyro 20 supplies signals which allow a determination of the north direction. That is Subject of the earlier patent application P 27 41 274.4-52 and shown again schematically in FIG.

909845/0089

The gyro 20 is arranged in FIG. 3 with its twist axis H parallel to the vertical axis z_, of the housing or frame 18. The input _{axis y G of} the gyro coincides with the axis 22 (FIG. 1), while the input axis x_ runs perpendicular to the spin axis of the gyroscope and the input axis y _r . The gyro is rotatably mounted in a cardan frame 38 about the input _{axis x G.} A tap 40 and a are located on the input axis x ″

ti

Torque generator 42. The cardan frame 38 is rotatably mounted on the frame about the input axis y_ «on the input axis y_ sits a tap 44 and a torque generator 46.

The output signal of tap 44 is switched to torque generator 42 via an amplifier. The signal from tap 40 is switched to torque generator 46 via an amplifier 50. The gain levels of the amplifiers and 50 are selected to be so high that the gyro 20, the cardan frame 38 and the frame 18 are practically electrically tied to the relative positions shown in FIG. If the axis z _G is arranged exactly vertically, then the ratio of the signals tapped at the outputs 52 and 54 and switched to the torques 42 and 46 is proportional to the tangent of the angle ψ between the input _{axis y G} and the north direction. In the event of a deviation between the vertical axis ζ and the vertical, which can be determined by the accelerometers 28 and 30, the output signals of the accelerometers 28 and 30 and the signals from the outputs 52 and 54 are fed to a signal processing circuit 56 (FIG. 2) , the attitude angle and the true course of the vehicle 10 is determined.

In this way, the north direction and the true heading of the vehicle with respect to that north direction will be established at the start of the journey determined. The gyro 20 is then pivoted by 90 into the position shown in FIGS. 4 and 5. According to the teaching of the Patent application P 27 41 274.4-52 the gyro then acts as a course gyro.

9Ö9845 / 0089 " ¹⁰ -

- yr-

In the present arrangement, the inertia measuring unit 16 also contains the rotational accelerometer 32, the one Integrator 58 is connected downstream and in this way the

F supplies angular velocity around the vehicle's longitudinal axis χ, while the gyro outputs 20 signals which

F F

speeds around the axes y and ζ, i.e. the transverse axis of the vehicle and the vertical axis of the vehicle.

The angular velocities w supplied by the gyro 20 and w about the vehicle transverse axis y or the vehicle vertical axis

F ^Z
z and that from the rotational accelerometer 32 and integrator

F 58 delivered angular velocity w around the vehicle longitudinal

F.
axis χ are switched to a transformation parameter calculator 60. As a transformation parameter between the vehicle-fixed coordinate system and an earth-fixed coordinate system

N system are the elements of the direction cosine matrix C ". A computer unit 62 is via an input 64 the

N
Initial values C ₇ -, (0) are supplied to the direction cosine matrix which

can be determined according to the teaching of patent application P 27 41 274.4-52. The computing unit forms from this and from the angular

K)

speeds ω
Direction cosine matrix according to the relationship

the time derivative C _p der

-NW F

FF *

where Ω is the rotational speed tensor

F F

- ω

- b)

- ta χ

is. The elements of the rotational speed tensor are calculated from the measured rotational speed signals

909845/0089

- 11 -

as follows:

F. ω ^ω ζ F. W. χ ^w z χ F. F. W.
y «Ν F. F.

- c

Ω "cos Φ

R + H

R + H ^V E

FF

where w, w χ y

the rotational speed signals ,, β “the

^ do

Earth's rotation speed, Φ the geographical latitude, V ", V" die East and north speed of the vehicle, R is the radius of the earth and H is the height of the vehicle above sea level. The so obtained matrix C "represented by nine elements integrated by an integrator 66, i.e. the integrator

"F.

integrates each of the nine elements of the matrix C _n , whereby the nine elements of the direction cosine matrix C, which is changed by the rotational speeds from the initial state, are obtained. As indicated by the connection 68, these elements are connected to the computer unit 62 which, with digital signal processing, now C_ in the next computing cycle

S forms with the new direction cosine matrix C_.

In the case of analog signal processing, the computer unit 62 would be a circuit arrangement with multipliers and adders, which of nine input signals from connection 68 and the three angular velocity signals ω, ω, ω nine

x y ζ

Forms linear combinations according to the rules of multiplication of matrices. These nine linear combinations are connected to nine analog integrators in the integrator 66, the outputs of which are fed back to the computer unit 62 via the connection 68. Via input 64, the elements of the direction _{cosine matrix C n} , namely the outputs of the integrators, are reset to predetermined initial values for the time t = 0.

909845/0089

Instead of using the elements of the direction cosine matrix as transformation parameters, the matrixing can also be done with the four elements of a rotational quaternion or directly with three Euler angles.

The transformation parameters for transforming a vector from a vehicle-fixed coordinate system (F-system) into an earth-fixed coordinate system (N-system), for example with the coordinates north, east and vertical, are at the output of the transformation parameter computer 60, in the form of the elements C, the direction cosine matrix _{C p is available.}

If the vehicle vertical axis ζ and thus the vertical axis ζ of the inertia measuring unit 16 is not exactly vertical, then components of the acceleration due to gravity g act on the two accelerometers 28 and 30. These components in the output signals of the accelerometers 28, 30 are compensated for by the output signals of correction signal generators 70 and 72, respectively. _{The direction cosines C 31} and C-, _{2 are} fed to these correction signal generators 70 and 72 from the output of the transformation parameter computer 60, the correction signal generators 70 and 72 delivering output signals gC ₃₁ and 9C _32, respectively. These output signals are superimposed on the signals from the accelerometers 28, 30 in summing points 74 and 76, respectively, whereby pure translational acceleration signals are formed which reflect the translational accelerations of the vehicle in the coordinate system fixed to the vehicle.

The translational acceleration signals obtained in this way are applied to integrators 78 and 80, the inertial velocity

F F

supply speed signals v _T or ν. Further speed

FF
signals V _n and V _n are from the speed sensors

^x Y ρ ρ

12 and 14 delivered. These speed signals ν _τ , ν

FF
or ν, ν are fed to an optimal filter 82.

909845/0089

The optimal filter 82 determines from the speed signals

T? "P ¹ P" P

v _T , ν, v _T and V _n optimized speed signals ν and ν for the components of the speed in a coordinate system fixed to the vehicle. Furthermore, the optimal filter 82 supplies correction signals C _x . for the transformation Jj Korr ρ _F

parameter CL ₁ and correction signals ν _v _, and ν „. for the i; xj \ orr yi \ orr

The speeds measured by the speed sensors (12, 14. The signals C i are sent via a connection 84 to a correction computer 88 which forms part of the transformation _parameter computer 60. The correction signals ν Ko and ν vKorr are fed to correction circuits 88 and 90, respectively. which cause a correction of the speed signals supplied by the speed sensors 12, 14. As a result, for example, the slip of chains or wheels in land vehicles with electromechanical speed sensors η can be taken into account.

In the case of land vehicles, it can be assumed that the lateral speed ν = 0. The speed sensor can then be omitted, so that the optimal filter 82 the value

F.
V _n = 0 is supplied.

With the speed components supplied by the optimal filter 82 ν, ν and that from a vertical channel 92

^ y F

supplied vertical velocity ν in a coordinate transform calculator 94, which also includes the corrected transformation parameters C "by the transformation parameter calculator are supplied to 60, the velocity components ^V E ^'v N ^{f V} D * ~ ^{n e} ^ - ^NEM space- or earth-based coordinate system by the relationship V = CL ₁ V is calculated. These speed components v ″, v ″, v_, are sent to a position computer 96

£ i IN YY

switched, which uses the usual methods of dead reckoning to position the vehicle to the north (N) East (E) and Altitude (H) calculated. From the values for the north and East position can be calculated from latitude Φ as specified in P 25 45 025.3. Φ is required for the calculation of the rotational speed tensor.

909845/0089

- 14 -

Although this is not necessary for the navigation method according to the invention, the course φ as well as pitch and roll angles 9- or Φ can also be determined and displayed from the elements of the direction cosine matrix by a position angle calculator 98, as is shown, for example, in patent application P 27 41 274.4- 52 is disclosed.

F For ships and land vehicles, ν = 0 can be set.

The structure of the optimal filter 82 is shown in FIG.

FF The speed _{signals v T} and ν are connected to one another in a summing point 100. The speed signals ν and ν are also switched against each other at a summing point. Feedback signals are superimposed on the difference signals in summing points 104 and 106, respectively. The signals thus obtained at the summing points are fed to a linearized dynamic model 108 of the system, which forms the core of the optimal filter 82, with time-dependent factors K _x (t) and K (t).

The model 108 thus receives a two-dimensional input variable State vector. It provides an output State vector χ with the components

χ =

FF FF

^V x ' ^V y' ^C Korr ' ^V xKorr' ^v yKorr

The block F (t) contains the coefficients as a time-dependent matrix of the linearized dynamic model, the order of which corresponds to the number of elements in the state vector χ. The mitj dt The designated block is formed by integration and linear combination of the components from the time-dependent weighted input signals the state vector x. This state vector χ forms the output variables of the optimal filter 82 and is also via the Block H, which is a matrix with two rows and a number of

909845/0089

- 15 -

Columns according to the order of χ symbolized into one implemented two-dimensional vector representing the two feedback signals.

- 16 -

909845/0089

Claims (3)

- xr- Claims ' 1.) Navigation device for land, air or sea vehicles,'"■ - containing: an inertia measuring unit with rotationally sensitive inertia sensors, which respond to rotary movements around axles fixed to the vehicle, and accelerometers which respond to Linear accelerations along axes fixed to the vehicle speak to, Speed sensors, which act on the speed components of the vehicle address above ground in the direction of predetermined axles fixed to the vehicle, and one Transformation parameter computer to which the signals of the inertia measuring unit are switched and which is used for Calculation of transformation parameters for the transformation of vector components from a vehicle-mounted one The coordinate system is set up in a fixed-earth coordinate system, marked by Correction signal generator (70, 72) to which transformation parameters from the transformation parameter calculator (60) are switched on and their output signals the gravity-induced proportions of the accelerometers (28,30) acting accelerations and the signals of the accelerometer (28,30) to Formation of translational acceleration signals are superimposed, - 17 - 909845/0088 ORIGINAL INSPECTE - vr - Integrators (78, 80) to which the translational acceleration signals are connected and which deliver inertial speed signals, a matched filter (82) to which the inertial speed signals and the signals from the speed sensors (12,14) and which speed signals are optimized taking these signals into account supplies in relation to fixed vehicle coordinates, a coordinate transformation computer (94) to which the optimized speed signals and the transformation parameters from the transformation parameter calculator (60) are supplied and to transform these speed signals into transformed speed signals is set up, which are related to a fixed-earth coordinate system, and a position computer (96) to which the transformed speed signals are switched and which is used for Formation of position signals is set up, which reflect the position of the vehicle (10). 2. Navigation device according to claim 1, characterized in that that from the optimal filter (82) transformation parameter correction signals are connected to the transformation parameter computer (60). 3. Navigation device according to claim 1 or 2, characterized in that that from the optimal filter (82) speed correction signals for correcting the output signals of the Speed sensors (12,14) can be generated. 90984 5/0089