DE3131111A1 - CIRCUIT DEVICE FOR DETERMINING THE NORTH DIRECTION - Google Patents

Description

PATENT LAWYERS Dipl.-Phys. JÜRGEN WEISSE · Dipl.-Chem. Dr. RUDOLF WOLGAST

BÖKENBUSCH41 D 5620 VELBERT 11 - LANGENBERG Box 110386 Telephone: (02127) 4019 Telex: 8516895

10 patent application

Bodenseewerk Geräteechnik GmbH, D-7770 Überlingen Gyroscope to determine the north direction

The invention relates to a gyroscopic device for determination containing the north direction

(a) a meridian spinning top suspended in a housing,

(b) a tap that points to the deflection of the meridian gyro responds to a housing reference,

(c) a torque generator, the 30th

(c,) around the vertical axis on the meridian top acts and

(c ") from the signal of the tap in the sense of a 35 Fixation of the meridian top to the housing

reference is applied, and

(d) a signal evaluation circuit that

(d,) is acted upon by the signal connected to the tap,
5

(d _? ) contains a filter and

(d,) provides a filtered signal which shows the deviation of the housing reference from north represents.

DE-PS 1 941 808 discloses a gyro device for determining the north direction with a on a band in a housing suspended meridian gyro known, in which a tap for generating a signal according to the azimuth deflection of the gyro with respect to a housing reference given by the band zero position is provided. A torque generator acts on the meridian gyro, which is generated by the signal from the tap is applied via a high-gain amplifier. This torque generator is exercising the meridian gyro generates a torque about the azimuth axis that corresponds to the gyro directional torque, i.e. the The rotation of the earth caused by the rotation of the gyroscope counteracts the north-orientated torque. Of the The meridian gyro then does not swing in the north with its gyroscopic spin axis, which is a lengthy one The procedure would be because the meridian gyro, which is suspended from a ribbon, has a practically undamped oscillation

"^ represents a system with a long period of oscillation. Rather the meridian gyro is electrically connected to the housing reference, i.e. the tape zero position, tied up. The torque to be exerted on the meridian top is proportional to the gyro straightening torque and thus at

° small angles between the centrifugal axis and north proportional to this angle. If you are at sufficient

high amplification of the signal delivered by the tap you can determine the angle between the gyroscopic axis and Can neglect the housing reference, the torque of the torque generator is proportional to the angle between housing reference and north. Can one assume that the torque generator works linearly, in this way, the amplified signal from the tap that is connected to the torque generator is supplied Measure for this angle between the housing reference and north. This signal can be used to indicate the north direction (DE-AS 20 08 702) or for navigation purposes (DE-AS 25 45 025).

Due to the electrical restraint of the meridian gyro and the oscillation period of the system significantly shortened. It can then be suspended in a freely adjusting tape compared to previously known Meridian gyroscopes determine the north deviation for a short time, i.e. the angle between the device reference and north will. Nevertheless, it still takes an undesirably long time before a stationary value for the North deviation has set. The measurement is also affected by external interference.

In order to eliminate the influence of such external disturbances, it is known to switch to the torque generator, as hatred for the north deviation serving signal to an analog-to-digital converter, the supplies a digital signal corresponding to this signal.

¹ ^ This digital signal is connected to a computer which is set up for recursive averaging from the digital signals sampled at specified time intervals. The averaging suppresses the influence of interference. Through this,

^aJ , however, is that the averaging takes place recursively

• ensures that a measured value is obtained relatively quickly Available (DE-OS 25 45 026 and DE-OS 26 18 and US-PS 40 75 764). If the measured value also initially may be flawed, however, it will be improved as the Averaging takes place. A low-pass filter is usually connected upstream of the analog-digital converter.

The invention is based on the object of further shortening the time within which a measured value is obtained with a desired accuracy in a gyroscope of the type defined at the outset, and of suppressing the influence of mechanical disturbances on the measurement.
15th

According to the invention, this object is achieved by that

(e) the filter is a Kalman filter, 20

(e,) which simulates the system of the bound meridian gyro,

(e ") on which as the first filter input signal ^ the difference of the on the torque generator

applied signal (Mg) and an estimated value supplied by the Kalman filter

(Mg) this signal is applied.

In the case of a Kalman filter, the system that supplies the measured variables is simulated by a model. One off The estimated value resulting from such a model for one of the measured quantities is identical to that actually in the system measured value of the measured variable and compared from the

Difference a filter input signal is formed. These

Filter input signals are multiplied by suitable time-dependent functions on integration means given and change parameters of the model until the filter input signals disappear. Then corresponds the model of reality, and on the model obtained in this way, estimated values for measured quantities of the System, e.g. as in the present case for the angle

do can be obtained between device reference and north.

It has been shown that by using such a Kalman filter to determine an estimated value Ji for the angle between the device reference and north in a gyro device of the present type compared to the known device described, a considerable improvement in both the setting time and in terms of the suppression of mechanical disturbances can be achieved.

Refinements of the invention are the subject of

Subclaims.

An embodiment of the invention is as follows with reference to the accompanying drawings

explained in more detail;
25th

Fig. 1 is a schematic perspective view of the mechanical structure of the gyro.

2 shows, as a block diagram, the linking of the various measured variables the gyro and the Kalman filter for signal processing.

Fig. 3 illustrates the adjustment process

in a known gyroscope
and with a gyro with
a Kalman filter.
5

4 illustrates the influencing of the setting process by disturbances in a known gyroscope and the gyro with a Kalman filter.
10

The gyroscope includes a housing 10 in which
a meridian gyro 12 is suspended from a mast 14 by means of a tape 16. The housing 10 defines
a coordinate system with the vertical axis ζ and
the axes χ and y, which are perpendicular to this and to each other.

The axis y represents a device reference. If the meridian gyro 12 with its gyroscopic twist axis 18 is determined by the y and z axes
Is level, the belt 16 is relaxed. This position is therefore referred to as the tape zero position. The deflection
of the meridian gyro 12 with respect to the device reference y is detected by means of a tap 20 indicated here as a potentiometer. The signal from the tap is over
a high-gain amplifier 22 is connected to a torque generator 24. The gyroscopic axis is
denoted by 26.

The following terms are used in the following

used, which can also be seen from Fig. 1:
30th

Cl = azumuth angle between gyroscopic axis 26 and
North

β = azimuth angle between housing reference y and north
35

^ & η = deflection of the gyroscopic twist axis 26 with respect to the housing reference

§ - elevation angle of the gyroscopic axis 26,

c = torsion spring constant of the belt suspension

m - mass of that formed by the meridian gyro 12

Roundabout pendulum,
10

r = length of the pendulum

g = acceleration due to gravity

I = moment of inertia of the centrifugal pendulum around the x-axis I = moment of inertia of the centrifugal pendulum around the z-axis

H = gyroscopic swirl

UJ = angular velocity of the earth's rotation φ = geographical latitude

M = that of the torque generator 24 from the amplifier 22 supplied signal,

My = H ω sin ψ

M .. = H ω cos ψ
N e

V = gain of the amplifier

1 + T _D s

VF _R (s) = V = transfer function of the amplifier

1 + T ₁ s

kers

s = variable of the Laplace transform

K .. (i, k = 1,2,3,4) = time-dependent functions

V _M = the variance of the measurement noise process of the signal applied to the torque generator

V eft = the variance of the measurement noise process of the deviation of the _{gyroscopic twist axis 26 from the housing reference}

M β = disturbance torque around the vertical axis Z Ma = disturbance torque around the x-axis

, W = power layers of the system noise inputs

At the top of Fig. 2 is the gyroscope, generally designated 28, in block diagram form shown.

The moment equation for the moments about the vertical axis ζ (Fig. 1) reads

(1) I ₂ e = M _e - Ha _e cos <P sin «- Hß - [vF _R (s) + ( ^{Y a} A

So I α is equal to the sum of the around the vertical axis ζ acting moments, namely the flow moments M,

of the gyro straightening torque as a result of the horizontal component 30

te of the earth's rotation H ta cos φ sine, the gyroscopic torque due to a rotational speed about the x-axis H β and the torque exerted by the torque generator 24 and the belt 16 on the meridian gyro 12. This latter torque is proportional to the angle "., By which the centrifugal axis 26 relative to the

Housing reference is deflected. The proportionality factor contains the gain of the Amplifier 22 (in which, for the sake of simplicity, the factor of the torque generator 24 is included).

The gain of the amplifier 22 has a time behavior F "(s) with a transfer function, which is indicated as a factor in equation (1) (mathematically not entirely correct).

The equation of moments about the x-axis results

(2) L) β = M ₈ + Hm sinqp + Hei - mrg sin P χ ρ e

I ρ is again equal to the sum of those around the x-axis acting moments, namely the disturbance moments Me due to external influences, the gyroscopic moment H ω sin φ, which is due to the vertical component of the earth's rotation, a gyroscopic moment H «due to Rotational speeds β around the vertical axis ζ and with the opposite sign of a Peldel moment P = mrg sinß that with a deflection of the meridian gyro 12 with the mast 14 from the perpendicular direction and thus with a Deflection of the gyratory axis 26 from the horizontal plane occurs. Since it is a heavy circle egg , β and ρ, i.e. the nutation, can be neglected will. In the case of fine alignment, that is, when the gyroscopic spin axis 26 is already essentially aligned to the north and α is small, sin ο can be replaced by «and sin p by ß. the end Equations (1) and (2) then result in the following linearized model equations

(3) Hi = Pβ - M _v - W _v (4) HP = - M _n * - M

JS.

A with -the Kompensatiorasmoment or idem, s to ..the --torque generator -24. Switched to f

(5) Mg Cs) =. = CV; F _r Cb) + ^ ₈ ) :: o _{: ft} Cs) 5

The torsion spring constant C is negligible because the reinforcement factor -V . in practice by three ZZe.hner potencies greater than CC -. The / disturbance moments Me and M

TO ^a

are in equations (3) and (4) as atochastic

Signals designated with WuW.
^s ν ζ

These model equations (3) and (4) are in FIG Black diagram-shown in the upper "part of Rig. -2.

A summation point 30 represents equation '(-41.! The deviation α of the gyroscopic twist axis ZG from north, cdi-e, as can be seen after .wind, in the "point ^: 32 ;: of the block diagram appears, is: multiplied by>

M _M - = "H ep cos φ, as shown by the block j34. This product appears with a negative sign at the summing point. 24 delivered torque M, the Djcoportional zder ^: ftbwexchang :: a the circle ^ eldrällacbse _Z6 (with

from the housing reference (with the azimuth angle α) and at point; 36 des. Block diagrams: -appears. This deviation α, dEft ^ from the 'tap ¹ ' 20 is multiplied by the gain factor ^ of the amplifier ~ 22, as shown in block J7: idar;, also appears with a negative sign 30. The third summand, rder; at the 'collecting point

'becomes effective is the magnitude W- representing the disturbance torque about the z-axis. According to equation (4), the summing point 30 results as the sum H ^. The deviation of the gyroscopic spin axis from north in the azimuth d, h «around the z-axis thus results in an angular velocity β around the x-axis (FIG. 1). This angular velocity results from the sum signal at the summing point by dividing by H _? which is represented by a block 36 'The angle of deflection about the x' axis

"^ Is obtained therefrom by integration, represented by a block 38, the Kreiseldrallaehae 26 thus searches at an angle β in azimuth relative to north, it its elevation angle to change. The elevation angle ρ causes, however, according to equation (3) through the

"5 pendulum moment P = m.r.g an angular velocity« around the azimuth axis z.

A summing point 40 in FIG. 2 represents equation (3) _e

^ ® The elevation angle § , which results from the integration symbolized by the block (carried out by the system), is multiplied by P = mrg. This product becomes effective at the summing point 40 with a positive sign. With a negative sign becomes

furthermore H ₁ , = H β sin «and the disturbance torque ν e τ

representing quantity M "effective. At the summing point Then, according to equation (3), H β results. The angular velocity β about the azimuth axis ζ is obtained by dividing by H, which is shown by block 44

is posed. Integrating the angular velocity m, represented by block 46, results in “at point 32.

A summing junction 48 represents the tap 20 where the difference between the angle ® GehäusereferenE

, ο

and north and the angle _a between the gyroscopic axis and north is formed and the angle «. supplies. One

(t)
Quantity W _a = ά represents stochastic disturbances of α, which when integrated, as represented by block 50, result in the angle α. As the initial value of the integration of _a (t) is predetermined.

This block diagram thus represents the gyro device 28 shown in FIG. 1 in a linearized form. 10

A signal evaluation circuit contains a Kalman filter 52, which is shown in the lower part of FIG is. This Kalman filter 52 forms the model of the gyroscope represented by the block diagram after. It provides estimated values for the various sizes that are characterized by a roof (λ). Mg is, for example, an estimate of that exerted on the meridian gyro by the torque generator 24 Torque or the signal applied to the torque generator. As the first filter input variable the difference between the signal Mg and that of

the estimated value Mg supplied to the Kalman filter 52 of this Signal.

Optionally, on the Kalman filter 52, as a second filter input signal, the difference of the deviation ο. of the meridian gyro 12 ″ from the signal representing the housing reference y and an estimated value α _{Δ supplied by the Kalman filter 52}

^ou this signal must be activated. This is indicated by dashed lines in FIG.

The filter input signals are time-dependent Factors multiplied and integrated, being by the

Integrals the parameters of the model can be changed until the filter input signals disappear. It can

it can then be assumed that the model modified in this way corresponds to the real system, so that the an The estimated values taken from the model reflect the real values occurring in the system.

In the preferred embodiment, the Kalman filter 52 following structure 5

In a first summing point 54, the difference

"IQ formed a first signal which represents an estimated value Mg for the signal switched to the torque generator 24, and a second signal which represents the estimated value u, multiplied by H ω cos ψ, of the angle between the gyro axis 26 and north.

"15, where, as I said, H is the circular twist, ω is the angular velocity of the earth's rotation and φ is the geographical latitude. The difference obtained is divided by the circular twist H, as indicated by block. The sum is formed at a second summing point 58 the difference between the first summing point 54 and the first filter input signal _{multiplied by a time-dependent factor [<2} o, the multiplication being represented by the block 60, divided by the gyroscopic swirl H.

And the sum formed in the second summing point 58 is integrated by integration means 62. The signal obtained in this way, which represents an estimated value β for the elevation angle of the gyroscopic swirl axis 26, is multiplied by a factor P = mrg, as shown by block 64, where m is the mass of the meridian gyro 12, r is the length of the gyro pendulum (FIG. 1 ) and g is the acceleration due to gravity. In a third summing point 66 the sum is formed from the integral multiplied by P from the integration means 62 and a signal M = H θ sin ψ "

ve

The sum formed in the third summing point 66 is divided by the gyroscopic swirl H, as by Block 68 is indicated. In a fourth summing point, the sum is formed from that caused by the gyroscopic swirl H divided sum of the third summing point and that multiplied by a time-dependent factor K ^ first filter input signal, the factor K being represented by block 72. the The sum formed in the fourth summing point 70 is integrated by integration means 74, the The signal obtained in this way represents the said estimated value cc of the angle between the gyroscopic axis and north, that multiplied by the factor M .. = H »cos <p represented by block 76 in the first summing point 54 is subtracted. The first filter input signal is with a time-dependent factor K ^ 2 represented by block 78, multiplied and then integrated by integrating means 80, where a signal is obtained which represents the estimated value for the angle between the device reference y and north. In a fifth summing point 82, the difference is formed from the integrated sum of the fourth summing point 70 and that with the factor K, ~ multiplied and integrated first filter input signal, a signal being obtained which has a

Estimate et. represents the deflection of the meridian gyro 12 against the housing reference y. In a sixth summing point 84, the sum is formed from the signal multiplied by a factor D , which was obtained in point 86 by * dividing the sum from the third summing point 66 by the gyroscopic twist H, which was multiplied by a factor γ.

¹ 1st difference from the fifth summing point 82, the filter input signal multiplied by a time-dependent factor K and, with a negative sign,

the estimated value multiplied by a factor γ - ι

Mg of the signal switched to the torque generator 24. The factor D through block 88, the factor γ through block 90 , 1 is the factor K. ₉

1 1

symbolized by block 92 and the factor γ by block. The sum formed in the sixth summing point is integrated by integration means 96, as a result of which said estimated value Mg of the signal connected to the torque generator 24 is obtained.

Optionally, the second filter input signal multiplied by a time-dependent factor K ₉₁ , represented by the dashed block 98, can be added to the second summing point 58, which, as said, is the difference between a signal representing the deviation of the meridian gyro 12 from the housing reference y and a the estimated value © supplied by the Kalman filter . this signal is. In the fourth summing point 70, the second filter input signal multiplied by a time-dependent factor K], represented by the dashed block 100, would then be added. The integration means 80, which supply an estimated value ^ of the angle between the device reference y and north, would additionally integrate the second filter input signal multiplied by a time-dependent factor K 1. The factor Kj is symbolized by block 102. Finally, in the sixth summing point, the second filter input signal multiplied by a time-dependent factor K, represented by block 104, would be added.

To form the first Filtereingangssigna s] ^ is formed in an eighth summing point 106, the sum of

the signal Mg actually applied to the torque generator 24, with the negative sign dem

A estimate Mg provided by the Kalman filter 52

this ** signal applied to the torque generator 24 and a signal V .. which represents the variance of the measurement noise process of the signal Mg applied to the torque generator. To form the second filter input signal, in a ninth summing point 108 the sum is formed from the signal β supplied by the tap 20 and representing the deviation of the meridian gyro 12 from the housing reference y. , with a negative sign the estimated value α _Α supplied by the Kalman filter 52, this signal representing the deviation of the meridian gyro 12 from the housing reference y and a signal V _a . , which represents the variance of the measurement noise process of the deviation of the meridian gyro from the housing reference.

As can be seen, the Kalman filter 52 forms the linearized one Gyro 28 system according to. Blocks 88,90,94 with integrator 96 are one Replica of the amplifier 22, its transfer function with

(6) VF _R (s) ₌ V

Is accepted. This model is supported by the Filter 3Q input signals from summing points 106 and 108 with time-dependent factors represented by the Blocks 60, 98, 72, 100, 102, 78, 92 and 104, which respond to the inputs of integration means 62, 74, 80 and 96 be varied until the filter input signals disappear and the model is adapted to reality.

Figures 3 and 4 illustrate the results achieved by the inventive design of the signal processing means compared to the prior art Advantages.

In Fig. 3, line 110 represents the real word of the

Angle »between the device reference and north. "ο

Curve 112 shows how the display of a device, for example according to Dt-OS 1 941 808, enters into this value «,

ig if the switched to the torque generator 24 Signal Mg is only passed through a low-pass filter for signal processing. Curve 114 shows the run-in of the measured value if, in addition to the low-pass filter, a mean value filter of the type described in US Pat. No. 4,075,764 is provided is, curve 116 finally shows the approach of the display in the real value when using the described Kalman filter 52. It turns out that the signal processing described is about three times as fast is like prior art signal processing. The signal processing described is permitted the estimate of the Winkel® to the nearest J ~ approximately 20 seconds, while with the known arrangement only an accuracy is achieved after 60 seconds of about 3 ~~ results in «.

Fig. 4 shows the behavior with regard to the suppression external disturbances again in comparison to the previously known solutions “.

Line 118 shows the real value of the angle _α . Curve 120 shows the course of the estimated value ^e when interference occurs when the signal Mg is only passed through a low-pass filter. Curve 122 shows the course of the estimated value for the same interference using a low-pass filter

1 an average filter according to US Pat. No. 4,075,764. Finally, curve 124 shows the course over time of the estimated value when a Kalman filter 52 described type is used.

Claims (5)

313111 Claims ! »J Gyro device for determining north direction containing (a) a merian top (12) suspended in a pendulum manner in a housing (10), (b) a tap (20) that refers to the deflection (%) of the meridian gyro responds to a housing reference (y), (c) a torque generator (24) which (c.) acts around the vertical axis (z) on the meridian gyro (12) and (c ") from the signal of the tap (20) in the sense a bondage of the fieridian gyro (12) to the housing reference (y) applied is and (d) a signal evaluation circuit that (d,) is acted upon by the signal (Mg) applied to the tap (20), (d _o ) contains a filter and (d,) provides a filtered signal which represents the deviation (β) of the housing reference (y) from north, characterized in that (e) the filter is a Kalman filter (52), (e,) which is the system of the bound meridian gyro (12) simulates, (e_) on which the first filter input signal is the difference of the on the torque generator activated signal (Mg) and one supplied by the Kalman filter (52) th estimated value (Mg) of this signal is applied. 2. Gyro device according to claim 1, characterized in that on the Kalman filter, in addition, as a second filter input signal, the difference of a signal representing the deviation of the meridian gyro (12) from the housing reference ( ^a _A ) ^and one of the Kalman filter (52) supplied estimated value (α _fl ) of this signal is applied, 3. Gyroscope according to claim 1, characterized in-OQ net that the Kalman filter (52) has the following structure: (a) The difference is formed in a first summing point (54) (a,) a first signal which has an estimate λ worth Mg for that on the torque generator (24) represents switched signal, and (a ") of a second signal, which is the estimated value multiplied by H β cos 9" represents the angle between the gyroscopic axis (26) and north, where H the spin §5 the angular velocity of the earth's rotation and ψ is the latitude. (b) The difference obtained is divided by the gyroscopic twist H. (c) In a second summing point (58) the Sum formed (c.) the difference from the first summing point (54) divided by the gyroscopic swirl H and (c ") the with a time-dependent factor K ~ _ multiplied first filter input signal (d) The sum formed in the second summing point (58) is integrated by integration means (62) , (e) the signal obtained in this way, which has an estimated value β for the elevation angle of the gyroscopic spin axis is multiplied by a factor P = m.r.g, where 5 m is the mass of the meridian top, r is the length of the top pendulum and g is the acceleration due to gravity. (f) In a third summing point (.66) the sum is formed from (f,) the integral multiplied by P of the Integration means (62) and 15 (f _o ) a signal M = Hu sin ». Α ν e ~ (g) The sum formed in the third summing point (66) is divided by the gyroscopic twist H. 20th (h) In a fourth summing point (70) the sum is formed from (h,) the sum divided by the gyroscopic twist H from the third summing point (66) and (h ") the one with a time-dependent factor K," multiplied first filter input signal 30 (i) The sum formed in the fourth summing point (70) is integrated by integration means (74), the signal obtained in this way said · estimate * of the angle between the circular axis (26) and north. (j) The first filter input becomes (j,) multiplied by a time-dependent factor K, “and then
5 (J ₂ ) integrated by integrating means (80) to obtain a signal which the estimated value α for the angle between Represents device reference (y) and north. 10 (k) In a fifth summing point (82) the difference is formed from (k i) the integrated sum of the fourth Summing point (70) and (k ") that multiplied by the factor K, _ and integrated first filter input signal, whereby a signal is obtained that Λ. nen estimated value <s for the deflection of the Meridian gyro (12) against the housing reference (y) represents. (1) In a sixth summing point (84) the sum is formed from VT ₀ (I ₁ ) which is multiplied by a factor (^ -) 1st signal obtained by dividing the Sum of the third summation point (66) was obtained by 3 "the gyroscopic twist H, (I ₇ ) the difference from the fifth summing point (82) multiplied by a factor T, ^e ^ ^nem time-dependent factor K._ multiplied filter input signal and, (Ia) with a negative sign, the one with a Factor (y) multiplied estimate Mg the shell on aen torque generator (24) signal. (m) The sum formed in the sixth summing point (84) is integrated by integration means (96) grated, whereby said estimated value Mg of the switched to the torque generator (24) Signal (Mg) is obtained. 4. Gyroscope according to Claims 2 and 3, characterized in that (n) in the second summing point (58) additionally multiplied the λλ by a time-dependent factor K " second filter input signal is added, (o) In the fourth summing point (70) the nc is added with a time-dependent factor K ,, multiplied second filter input signal, (p) by the integration means (80), the one Estimate * of the angle between device efeo on renz (y) and north deliver, in addition that with a time-dependent factor K ,, multiplied second filter input signal is integrated and (q) in the sixth summing point (84) additionally multiplied by a time-dependent factor K. second filter input signal is added. 5. Gyro device according to claim 4, characterized in that (r) to form the first filter input signal in an eighth summing point (106) the sum is formed by (r,) that on the torque generator (24) actually activated signal Mg, 10 (τy) with a negative sign, the estimated value Mg supplied by the Kalman filter (52) of this signal applied to the torque generator (24), and 15 (r,) a signal that shows the variance of the measurement Represents the noise process of the signal applied to the torque generator (24), and
20th (s) to form the second filter input signal in a ninth summing point (108) the sum is formed from (s.) the one supplied by the tap (20), the Deviation of the meridian gyro (12) from the housing reference (y) representing signal & . , (s ") with a negative sign, that of the Kaiman filter (52) supplied estimate worth ß. this the deviation of the meridian gyro (12) from the housing reference (y) representing signal and 35 (s,) a signal that shows the variance of the Heß- and Rausch process of the deviation of the Meridian gyro (12) from the housing reference (y) represents.