JPS5870167A - Angular speed sensor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention reduces the accumulation of gyro output angular errors caused by lock-in angular velocity by dithering, or biasing, a laser angular velocity sensor by 2>-ff. This invention relates to an improved method. Apparatus for implementing this novel table method is also disclosed.

In a simple laser angular velocity sensor, sometimes referred to as a Ring-Lazer-Jade, two monochromatic light beams are directed in opposite directions along a closed-loop path that defines the central input axis at which the rotational speed is to be detected. will be issued. As the ring laser gyro rotates about the input axis, the length of the effective leop path traveled by one beam is lengthened and the effective lep path length traveled by the other beam is shortened.

As a result, the path lengths of the two beams are changed and the frequency of the i-beam is changed, with one being
the other becomes lower. The reason is that the frequency of the laser beam depends on the length of the rapping path. The frequency of the two six waves, and thus the difference in the frequency of the two waves, is a function of the rotation of the closed loop path, and a phase relationship is defined between the two waves that is a function of the rotation of the two waves.

Vibration of two beams #! When I differs, the phase φ between the beams changes at a rate proportional to the difference in their frequencies. The total phase change Δφ between the two beams is proportional to the time integral of the frequency difference and proportional to the time integral of the input rotational speed about the input axis of the gyro. Therefore, the total phase change over a certain time is the full angle around the input axis during the integration time! Il indicates the displacement, and the phase change rate dψ/di between the two waves indicates the rotational speed about the input axis of the gyro.

However, at low rotational speeds, the frequency difference between the two beams is small and the two beams tend to resonate or "lock in" to each other so that they vibrate at only one frequency. Therefore, in a simple laser gyro, the frequency difference is zero at low rotational speeds, making it impossible to measure low rotational speeds.

The rotational speed below which the difference in frequency between the openings of the two beams becomes zero is generally called the "lock-in speed." When the gyro rotates below the lock-in speed and the beam is locked in, the gyro's output angle error is zero.

Of course, the inability to accurately measure low rotational speeds reduces the effectiveness of laser angular velocity sensors in navigation equipment.
Become. Therefore, in order to use laser angular velocity sensors more effectively in navigation equipment, much research and development has been conducted in the field of laser angular velocity sensors with the aim of reducing or eliminating the effects of "lock-in." ing.

1. To reduce or eliminate the influence of “Four-Queen”
U.S. Patent No. 11411 No. 3, the technology of which is owned by the applicant
No. 373,650. Disclosed in that patent is a laser angular rate sensor in which an O element is provided to introduce a frequency bias into two light beams traveling in opposite directions.

The applied frequency bias is such that a large frequency difference (like that which occurs just before "lock-in") exists between two beams of light traveling in opposite directions for most of the time. . Sarak.

The sign or polarity of the frequency difference introduced is 1 such that after one complete cycle of periodically reversing bias, the time-integrated frequency difference between the two optical biases #1 is zero. be periodically reversed.

Near the time when the sign or direction of the bias reverses, the frequency difference ranges from the p-in velocity to zero, so there is a tendency for the bias to become "locked in."
The period of "lock-in" is very short, and as a result the possibility of gyro output angle differences being accumulated is greatly reduced. However, errors still accumulate in the gyro output angle signal and eventually reach a troublesome level.

This is especially true in navigation equipment.

An improvement to the biasing device shown in the aforementioned US patent is disclosed in commonly assigned US Pat. No. 3,467,472. This U.S. patent includes the aforementioned U.S. Pat.
In addition to periodically varying the bias as shown in No. 50, the small gyro output angle errors that live around the time when the bias reverses to 1 are randomized so that the average cumulative error becomes smaller. A bias device is disclosed that provides randomized bias. Although this improvement is sufficient, it is necessary to further reduce the lock-in error in order to widely apply laser angular velocity sensors to inertial navigation systems.

The present invention provides a dithering or biasing system for a laser angular velocity sensor to significantly reduce the effects of lock-in. The frequency bias introduced by this improved biasing device fK is used to adjust the frequencies of the two light beams traveling in opposite directions and the phase between them to a predetermined angle. , the error accumulated during at least two successive bias periods or dither cycles approaches zero. Techniques that exploit the amplitude of frequency biases can be implemented with or without using the random-match bias principle.

A laser gyro assembly consists of a lasing medium that provides two electrical energy waves of approximately single frequency, here referred to as optical beams, and a plurality of reflectors that form a closed loop path or enclosed region. be done. The axis perpendicular to the enclosed area is generally defined as the gyro input axis. The two light beams travel in opposite directions along a closed loop path. That is, the beams are in opposite directions. A readout device fjI is provided to monitor the frequency difference between the two light beams traveling in opposite directions.

The extraction device detects the instantaneous phase of the two beams traveling in opposite directions, and distinguishes between the corresponding clockwise and counterclockwise inertial rotations of the closed loop path centered on the gyro input axis. K to do.

Two detectors are used to distinguish between positive and negative phase changes. Note that the rate of change of phase between the two beams scales the rotational speed, but the zero speed is indicative of a twin or zero rotational speed.

Hereinafter, the present invention will be described in detail with reference to the drawings.

Figure 1 is based on U.S. Patent Nos. 3373650 and 346747.
2 shows a typical well-known ring laser gyro 100 shown in No. 2. The laser generating medium 10 has two beams 11 which travel in opposite directions to each other and have a substantially simple frequency.
．． yields 12. Those beams are reflected 913, 14 .
Proceed along the triangular closed loop path formed by 15.

This closed loop path is shown surrounding an orthogonal reference axis, herein referred to as the gyro input axis, 26.

Closed loop paths can be created in several ways. For example, the reflector 13 can be a U-spherical surface 913' if desired. This concave mirror allows alignment of the optical path. The position of the reflecting mirror 140, which is a plane mirror, can be controlled by the transducer t14. In order to optimally perform laser oscillation, the reflection fa 14 can be positioned to control the optical path lengths of the two light beams traveling in opposite directions.

Such a transducer is disclosed in commonly owned US Pat. No. 3,581,227. Additionally, the optical path length control device is disclosed in U.S. Patent No. 415297 owned by the applicant.
It is disclosed in No. 1.

The combination of the reflecting mirror 1s, the combined prism 21, and the detector 22 constitutes a laser gyro reader. Reflector 15 is shown as a semi-transparent plane mirror. Therefore, part of the energy of the light beams 11, 12 can be transmitted through the mirror 15.

A portion of the energy of the beam 11i2 transmitted through the reflecting mirror 15 is incident on the combination prism 21, and the output light beams 11' and 12' from the combination prism 21 are made orthogonal to each other.

These light beams 11/, 12' are uniquely related to the frequency and phase of the two light beams 11, 12 traveling in opposite directions. Their light beams 11'.

12' are superimposed by a detector 22 to produce an interference stripe pattern consisting of alternating bright and dark bands IK, side by side. The interference fringes indicate the behavior of the instantaneous phase relationship between two light beams traveling in opposite directions. If two light beams traveling in opposite directions have the same frequency, the instantaneous phase between the two light beams traveling in opposite directions will be constant, and the interference pattern will be constant. However, if two light beams traveling in opposite directions have different vibration #1, the instantaneous phase relationship of those beams will change over time, and interference will occur depending on which of the two beams has a higher frequency. The pattern appears to move to the right or left. Therefore, by monitoring the instantaneous phase relationship between the two light beams, the magnitude and direction of the rotational movement about the input axis 26 can be determined. The direction of the motion, the direction of the phase change, that is, which beam has the higher frequency, is determined by K, and the angle of rotation, that is, the angular displacement of the closed loop path from a certain reference position, and the change in the number of fringes. , n1llJ is defined by that portion passing through the fixed reference mark of the detector.

Each complete change in interference (ie, maximum brightness to minimum brightness, minimum brightness to maximum brightness) represents a phase change of 2z radians between the two light beams.

The rate of change in the movement of the interference field is determined by the laser gyro input shaft 26.
Indicates the rotation speed around .

An example of an apparatus for detecting the laser beam phase of two laser beams is shown in FIG. 4a.

This device consists of two detectors 22ae22b arranged on the output side of the combined prism 21 and spaced apart by about 1/4 (λ/4) of the interference stripe spacing. The physical dimensions of the device depend on the optical relationships involved in the device. Detector 2
2m and 22b can be constituted by a photodetector that generates an output signal indicating the strength of the interference stripe pattern. Detectors 22a, 22
By separating the interference stripes by about one fourth of the spacing of the interference stripes, a phase of the photodetector can be obtained such that the direction and magnitude of the motion of the interference stripes can be monitored. When the gyro is rotated clockwise, the interference stripe pattern Fi moves in one direction, and when the gyro is rotated counterclockwise, the interference stripe pattern Fi moves in the opposite direction. By counting the number of maximum and minimum brightnesses resulting from the movement of the interference fringes (from bright to dark) through one detector, the rotation speed is determined, and the rotation speed of the detector 2 is determined.
By comparing the changes in the directions of the two bright transmission signals given (2a*22bK), the direction of rotation by K is determined. The brightness value detected by each detector indicates the instantaneous phase between the two light beams traveling in opposite directions. As explained later, each party beam is offset by a different offset angle β.

At each time each detector responds to a different brightness as shown in FIG. The output of each detector is directly related to the phase φ between the beams offset i by some offset phase constant β that depends on the spatial location of the detector relative to the brightness of the pattern and the instantaneous phase φ. In the example shown in Figures 1 and 2, the value of β is π/2 radians. If the detector is perfectly positioned id, its value of β will match λ/4K. In the following discussion, the value of is indicated by an expression containing φ.

Referring again to Figure 81, the outputs of the detectors 22ay22bO are processed by a well-known signal processing circuit 2 for processing the outputs of the detectors to determine angular rotation, magnitude, orientation, and angular displacement.
given to 4. An example of this signal processing circuit 24 is disclosed in U.S. Pat. No. 3,373,650 and U.S. Pat.
No. 7425. The output of each detector is amplified and then used to trigger a digital detector that monitors relative positive and negative counts. Each count represents a 2 radian phase change of the two light beams traveling in opposite directions along a closed loop path about the input end 26. The relationship between each count and the angular displacement of the angular velocity sensor depends on the sensor's relationship between the input velocity and the bias frequency difference (ie, the scale 7 actor). For example, ] degrees/hour (1 of the rotational speed of the fi sphere)
/15) It is possible to make a laser gyro with an inertial input rotation speed relationship. This laser gyro converts the frequency difference between the two light beams within the laser gyro cavity into IHz lfc. One hour and one degree is exactly one arc second of time. Therefore, one arc second of inertia angle is generated every second, resulting in a phase change of 2 radians between the two beams. The reason is that the parasitic number difference I over an integration time of 1 second
This is because the time integral of H is 2π radians. Then, each count has a weight of 1 arc second, and K. If the sensor rotates 360 degrees about the input axis, that is, one rotation, an output of 1296,000 kakunts is generated.

A rotation in one direction defines those counts or pulses as positive, and a rotation in the opposite direction defines those pulses as eclipses. (The logic is similar to the logic used in digital incremental angle encoders.) Typically, the closed loop path shown in FIG. It is supported by a support element 25. Although detector 22 is also shown as being supported by support element 25, detector 22 can also be mounted externally to support element 2S. In Figure 1, the laser generating medium is shown to be in the optical path of two light beams passing in opposite directions, but the present invention is not limited to such a structure. The lasing medium is resonant within the support element 2! ! 9) It is desired to generate two beams of light that extend in opposite directions along a supported closed-loop path.

Next, the operation of the laser angular velocity sensor shown in FIG. 1 will be explained in detail. When there is no rotation about the input axis 26, the frequencies of the light beams 11 and 12 are equal and the light beam 1
The pattern created on the detection 1922 by 1'12' is a constant tt.

When the inertial table 25 rotates about 1 m 126, the frequency of one light beam becomes high and the frequency of the other light beam becomes low depending on the direction of rotation. Correspondingly, the waveform on the detector 22 created by the beams 11', 12' moves with a speed proportional to the difference in frequency of the two beams 11, 12. Any detector 22a*22
The brightness measured by bK is that of beam 1 traveling in opposite directions.
Indicates a phase between 1 and 12. The rate of change in phase indicates rotation, and can be expressed mathematically by the following equation (1): where 1φ = instantaneous phase between the two light beams 8 = scale factor of the dial; The input rotation speed ω of the gyro is the lock-in speed of the gyro.

Equation U) describes the lock-in error relationship between the input speed and the apparent phase relationship. The rate of change in phase is directly related to the input speed, but the lock-in speed ω of the gyp,
It should be noted that there is a change in the error term containing . When the input rotational speed is low ωLL, the error term is very large.
hs This error term is usually called the lock-in error and is particularly troublesome when determining angular rotation.

The phase relationship between the beams can be observed using a photodetector of much smaller dimensions (than the spacing of the interference fringes).

The rotation speed can be measured by a stone plate that records the distance between the interference stripes, or the speed at which the brightness of the umbrella height moves through the detector. The speed of movement is proportional to the difference in frequency. Each time the interval of one beam is recorded is 2f? between the two beams. Represents the phase change in Gian. The integral of the frequency difference over time (counting the number of changes in the stripes) is, as mentioned above, proportional to the total phase change between the two beams, and therefore the integral time of the closed loop path about the gyro input axis. It is proportional to the amount of full-width combustion inside. Mathematically, this is expressed by the following equation.

ζ Here, 1Δφ is the total amount of phase change (in radians) during the integration time of the phase between the beams 11 and 12 whose frequencies are fg and fl, and its sign indicates the direction of rotation.

Each time that one stripe interval is detected can be called a "count." Count lI number and scale 7
The fraction of the total force multiplied by the actor indicates the angular displacement during the integration time, and the rate of change of the count indicates the rotational speed.

Equation (1) can be expressed in various units using the output count of the photodetector 22, and is shown in parentheses.

! = sensor input angular displacement expressed in force9nt, d! /dt
is the sensor input speed P expressed as a count of 7 seconds; gyro lock-in speed expressed as a count of 7 seconds 0=angular displacement output of the gyro expressed as a count, dO
/dt is the jar output speed including lock-in error.

Due to lock-in, contribution power of 0 is actual input! may not be equal to . The output angle lock-in error of the gyro is (as shown in the first generation, the lock-in error difference i!LgV
c.

g = o - i (3) Equation (3) shows that the gyro's output angular count is equal to the input angular displacement plus a certain error based on the angular rotation about the gyro's input axis.

0! r+1! (4) Expression (4) is converted into (2
) Substituting it into the formula gives the amount difference formula (town) expressed by the gyro output quant.

= M = FLall (2K(t+g)) (s
) t @) length describes the lock-in error inherent in a type ring laser angular velocity sensor as shown in FIG. The output of this sensor is a signal related to the inertial input angle measured by the sensor and is provided by signal processing device 24. The senna output includes a lock-in difference which is described by equation (5). In the following discussion, it is assumed that there is a senna output signal that includes a lock-in error and is related to the inertial input to the sensor.The purpose of the present invention is, of course, to eliminate the lock-in error contained in the normal senna output signal. The goal is to minimize the error. (5
) will become clear from the following explanation.

As mentioned above, U.S. Pat. A laser gyro is disclosed in which a bias is applied that periodically reverses the frequency of the beam.

The reversing bias is of such a nature that the time-integrated frequency difference between the two light beams is approximately zero after one complete cycle of the periodically reversing bias. (The bias shown in U.S. Pat. No. 3,373,650 is periodic or repeatable, but it does not have to be periodic; it does not have to be periodic; it just requires a sufficiently large number of inversions per second. ) As disclosed in that U.S. patent, the periodic table inversion of the biases t2Km! When a rotational motion is imparted, the difference in frequency between the two beams can be determined mechanically, for example by acting directly on the lasing path, i.e. the lasing medium. ii! By changing K, you can do a lot of work. The fool's solution is referred to in the above-mentioned US patent as providing an "electrical k" bias.

In the mechanically biased method, the loser gyro is simply electromechanically biased around the gyro's input axis so as to maintain the effective gyro input rotational speed higher than the lock-in speed most of the time. Normal/reverse vibration, or dithering, is caused, and the input rotational speed simply reverses direction periodically.

The frequency of each beam is affected by the vibration (dithering motion) about the gyro input axis that is applied (by this mechanical biasing method), so that vibration in one direction will cause the frequency of one to be higher. However, the frequency of the other one is lower, and the vibration in the other direction becomes Km in the opposite direction of the frequency. If the frequency of the oscillatory motion is high enough and the effective rotational speed caused by that oscillation is high enough, the IK between the beams will be low because the difference in the varying frequencies will exist for most of the time. Most of the effects of lock-in can be avoided even when measuring the first speed longitudinal. In the method of electrically biasing,
To directly separate the frequencies of a laser beam by causing a change in the laser generation optical path.To add a frequency bias to two beams traveling in opposite directions.To add a frequency bias in the optical path of those beams using electro-optical devices such as Faraday media. In the mechanically biasing and electrically biasing methods disclosed in U.S. Pat. No. 3,373,650, the frequency of at least one of the beams is biased or adjusted to such that a frequency difference exists between the beams for most of the time. The applied bias periodically reverses, i.e. the "sign" of the frequency difference
, the time integral of the frequency difference between the two beams is equal to one bias cycle, or dither.
- Cycle Itch9 is almost zero.

A periodically reversing biasing device 30 is provided for biasing the frequencies of the two beams traveling in opposite directions.
The base 25#c is connected via the base 25#c. In a mechanical bias device, the bias device 30 mechanically rotates the pace 25 in a positive direction and a reverse direction around the input shaft 2 of one gyro so as to change the frequency of at least one side. Any device that introduces changing frequency biases of alternating sign can be used. In a practical sense, although biasing device 30F1 typically produces a periodically reversing frequency bias, periodicity is not necessarily required; i.e., the frequency bias is fully Km to provide useful lock-in error reduction. It doesn't have to be reversible.

The rotational motion caused by the biasing device 30 is herein referred to as dithering motion.

The actual rotation to be determined by the gyro is defined as an inertial motion input. Therefore, the gyro or the gyro input shaft 2
The sensor input movement (2) actually measured around point 6 is the sum of the inertial input movement and the dither movement. Therefore, in order to obtain an output signal indicative of only inertial input motion, K must provide means for discriminating between inertial input motion and dither motion. Such discrimination means are well known and are not shown in FIG. An example of such a discrimination technique is the rice a.
+* Shown in Grant No. 3373650.

As mentioned above, when the rotation speed is low, mutual i
The frequency difference between the two beams traveling in opposite directions is also high, and a bias is applied to maintain the frequency between the beams.・The time at which the mechanical bias reverses direction. Nearby, the sign of the frequency difference changes and the corresponding bending rate dψ/dtFi of the phase ψ between the beams becomes zero. These times are referred to herein as "zero speed crossings" and are important in describing the increase in lock-in error. In electrical or electromechanical biasing devices, an eiK% "zero speed crossing" occurs where the sign of the frequency difference is reversed.

Transcendental function equations (1), (2)a of gyro output angular velocity
, is a function of the instantaneous phase angle of the opening of the two beams traveling in opposite directions, the sensor lock-in velocity, and the phase angle measurement offset. In order to solve the Vn) equation to obtain the actual amount of lock-in velocity, a time-varying equation for the value φ or OK is first obtained. It can be provided by a varying bias.

Then 1 U.S. Pat. No. 3,373,650 and 3,467,472
A device similar to the bias device disclosed in No. VC will be described below. In a mechanical biasing device, the ring-laser gyro 1000 base 725 is periodically rotated in one direction and the opposite direction, and the difference in the frequencies of two beams traveling in opposite directions is a sine. If it is changed in a wavy manner and its sign is periodically alternated, it becomes . In such a situation, as the pace 25 rotates in one direction, the magnitude of the instantaneous phase angle between the beams increases continuously over time.

When the direction of the base rotation is changed by 250 (zero speed crossing)
, the difference in frequency that becomes more convenient over time tends to zero. ・At each zero velocity crossing, the second derivative dlψ/dt"!' increases by 1 yx*
In particular, the sign of the second derivative corresponds to the direction of the rotation angle.

FIG. 11 is a graph showing the error resulting from the relationship expressed by equation (5) for a dithered gyro at the completion of a zero speed crossing region where the direction of rotation is reversed.

A curve 412 is a graph showing the relationship between the gyro speed output and time, and shows a decrease in the frequency before the zero speed crossing at time TOK and an increase in the frequency after that. The amplitude of the curve 412, which is constant, depends on the lock-in speed ωLt or PL (unit: count) of the sensor. Curve 413 gyro angle output wA%g
is obtained by integrating the curve 412. This error 8 oscillates with varying frequency and amplitude before the change in direction, and represents a step of increasing fill angle 1 across the direction of change.

1. As can be seen from the figure, the error given by equation 1(5) always exists, but has its most important effect on the zero speed crossing. In the case of a ring laser gyro that is periodically dithered in a sinusoidal manner, such changes occur twice for each dither cycle, as shown in curve 413, at each zero speed crossing. Such errors occur. Unfortunately, in conventional biasing systems, their lock-in errors are not necessarily equal in magnitude, nor are they always opposite in sign, which tends to accumulate errors in the gyro's output. This is sometimes called Random Drift-O or Random Nine Orcs.

The above discussion concerns a mechanically dithered gyro. However, optically or electrically dithering
Since the characteristics obtained are similar to the characteristics described above, the following description will not be clear.

In the bias arrangement mrtc of the present invention, the errors accumulated over a series of successive dither cycles are zero! The frequency bias is controlled to change the instantaneous phase between the two beams proceeding at KW during subsequent zero velocity crossings.

Next, a novel bias device of the present invention will be explained.

When the inertial input rotational speed is zero, only the sensor rotational speed is generated by the dither movement around the input shaft 26 of the laser gyro, and the laser gyro rotates in a positive sinusoidal manner around the input shaft 26. Let us explain the situation in which the dither is dithered in the direction of reverse rotation.

FIG. 2 shows a wire 7 showing such a situation. Figure 2 #
C is the input dither angle of the concentrator, i.e. the true gyro input angle I (counts) about the gyro input axis 26;
and time over several dither cycles when the dither motion is completely sinusoidal. It should be noted that ".count" corresponds directly to the phase angle change in 2π Luans. If there is no gyro lock-in speed, no slope or accumulation will occur since the gyro output angle 0 is zero after one complete dither cycle. Another way to express this is
This means that the time integral over the period of the dither cycle of the frequency difference of two light beams traveling in opposite directions is zero. However, as shown in FIG. 11, the cumulative output angle error B or K occurs due to lock-in.

Although the dither shown in FIG. 2 is sinusoidal, its role in M& of the gyro output angle error g can be appropriately expressed by considering the dither as parabolic. In other words, in the case of a positive scissor half cycle, the maximum dither angle is an upwardly convex parabola;
In the case of a half cycle, it can be considered as a downwardly convex parabola whose maximum dither angle is θ. Therefore, the positive dither angle parabola (i.e., the gyro inertial input angle) can be expressed by the following equation, and the negative dither angle parabola can be expressed by the following equation. Note that the unit ``count'' has a corresponding unit of the phase change between two beams traveling in opposite directions. The positive dither angle paraboloid IiI is d3ψ/dt or 6
The negative dither angle parabola corresponds to a first polarity of dzφ/di'' (1i opposite to dzφ/di'').

First, we will explain the positive Nizer angle paraboloid class.

Substituting equation (6) into the v4 difference equation (51), unless the quality of the laser fist gyro is unacceptably low, the change in error E over several dither half-cycles is negligible. Therefore, The seagull on the right side of equation (8) can be considered to be constant. Then, if equation (8) is integrated over time from minus infinity to plus infinity, then for a positive dither angle paraboloid #, Equation (9) can be obtained that expresses the output angle error that increases.

The above integral is based on Fresnel integral properties.

The expression for the increasing error for the dither angle paraboloid 1Iilk of IjKz ia can be found in a similar manner.

For practical purposes, -1 and 1° can be expressed as a single VcO since #1#f is strong. However, #for #
It is important to remember the difference between the two, because even a small difference between the numbers can cause a big difference in the triangle.

Complete l dither-11? Total error increment over cycles,
It can be expressed as the sum of the 9 errors accumulated on the positive dither angle parabola function and the sum of the errors accumulated on the negative dither angle parabola - 0 function. The sum is Δ1 - 1ΔB. For this ζ, m, =x#, +.

2θ weight + i. Using simple trigonometry formulas, equation (12) becomes K as follows.

A, -m ((2) 2N: (ε 10 ---- upper)) (13) Only inertial rotation around the gyro input shaft 26 is dithered.
Assuming motion, equation (ta) is completely dithered.
・Total incremental gyro output angle error Δ accumulated during the cycle
Represents G.

(13) 1 perfect l dither due to the error expressed by Eq.
- When the angular displacement around the gyro input shaft 26 is zero during a cycle, the gyro output angle indicates that the gyro has rotated by a certain angle.

In a navigation device, this is shown by a certain angular rotation. This is, of course, a mistake. The reason for this is that when formula 03) was determined, it was assumed that there was no Senna motion other than the dither motion. Each zero speed crossing in each dither cycle constitutes a clock-in error. Therefore, the gyro output angle error resulting from each dither half cycle is cumulative. As a result, the accumulated (1
The error expressed by equation 3) is an increasing contribution of the lock-in error, previously referred to as random drift or random quota. When a laser gyro is operated continuously, if the cumulative arbitration becomes too large, it cannot be used as a precision navigation device, and therefore, the accumulation becomes too much! It is necessary to minimize the difference or eliminate the error altogether.

In the present invention, it is represented by formulas (12) and (13). The cumulative gyro output error angle for each dither cycle is:
The instantaneous phase difference between two beams traveling in opposite directions is
In the subsequent zero speed crossings, jin and k are changed by a predetermined value.
You can significantly reduce KfIR. The mechanically biased system described above can handle instantaneous phase differences by varying the maximum positive and negative dither amplitudes by a preselected amount at subsequent zero speed crossings.

FIG. 3 shows a block diagram of one embodiment of an error cancellation biasing device employing the principles of the present invention. ring 9
A laser gyro 100 is coupled to biasing device '30 via a coupling element 31 similar to that shown in FIG. The bias device 30 can be constructed either mechanically or electrically. For convenience of explanation, a bias device [30 and a coupling element 31] are used to vibrate the ring laser gyro 100 about its input shaft 26, and to move the IK in mutually opposite directions within the ring laser gyro 10G.
Assume a mechanical configuration in which the frequency bias of two beams can be periodically reversed.

This can be done, for example, using a motor coupled to pace 25. Bias device 30 is controlled by a bias control signal provided by bias control signal generator 32.

The bias-control signal 4 seen from the bias-control signal generator 32 to the connecting element 33 combines the output of the first signal generator 34 resulting in an output of the form ＾dB(2πFd t) and the output of the first signal generator 34 of the form Km(2fFxL). It is the sum of the output of the signal generator 35 of 1g2 which produces the output.

The output of these signals added together by the adder 36 is a bias control signal for controlling the bias device f30. PXe
=Fd/2, the bias control signal has a maximum positive and negative swing of 11! is consumed periodically, resulting in a sine wave signal. The periodic variation in the amplitude of the bias control signal is determined by a second signal generator 35 having a selected amplitude and frequency F8. The frequency of the sinusoidal change is F
It is determined by d.

Figure 4 Company, lock-in error during normal sensor output is increased by 1
The present invention's Tomihiro difference cancellation bias teaser is reduced to 1.
It is a graph showing movement. 41!1 shows a graph of the dither motion provided by the embodiment of the present invention shown in FIG. The maximum dither negative amplitude provided by bias device 30 is periodically varied to a preselected gMK determined by a bias control signal provided by bias control signal generator 32. . Fxae
For Fd/2, the first sinusoidal dither angle shown in FIG. 1 has a maximum positive dither amplitude 0□ and a maximum negative dither amplitude θ. Second sine wave dither
The maximum positive and negative swings of the cycle are each 0. .

θ4. The third dither cycle is the same as the first dither cycle 2, and so on. The total incremental gyro output angle error from two successive teaser cycles is the sum of each incremental difference in each half cycle of each dither cycle, equation (9) # (11), It can be found that K can be applied to the two subsequent dither cycles shown in the figure, and can be expressed by the following equation (14).

Δft (2 cycles) + 6g (as) + ΔB (θ,) +
6g (ls) + Δ■ (04) (14) The total incremental gyro output angle error described by 04) 2 for two subsequent dither cycles is K if the relationship shown by the following equation is true. ], it can be reduced to zero.

C16) Same as before It is assumed that the dew is small but constant during the following few cycles.

The relationship shown in equations (15) and (18) is θ breath−
θ heat = N±1/2 count (17)'l
'4 = N top 1/21yt:y) (
18) is always true. In these formulas, N is any integer.

Equations (17) and (18) are the maximum positive dither angle θ1
．． 0s differs by a partial difference of ±172 of the count,
Assuming that the negative maximum dither angles, , and θ4 differ by ±]/2 kakunts, the resulting increased gyro output angle error for two subsequent dither cycles with this relationship is zero. shows.

That is, the lock-in error related to the senna output is t1! as described above. Be reduced to nothing. It is important to emphasize that only the partial difference in counts between maximum dither and negative amplitudes is significant. The reason is that the integer part of the force 9 nt is 2
This is because it corresponds to the integer part of the 2s phase cost conversion between the two beams and has no effect on the reduction of the lock-in amount difference (
Equation (14), (1B).

Refer to the triangular relationship shown in (16) N4).

Referring again to the FGA diagram, the 34-digit signal generator, the second
1. so that the ring laser gyro 100 has the largest positive and negative dither amplitudes when operated independently of the signal generator 35. Can control each bias device. Second
When the first signal generator 34 is operated independently of the first signal generator, the laser gyro 100 achieves maximum dither.
The amplitude of the output of the second signal generator 35 is selected such that the second signal generator 35 can control the biasing device 30 to have the square root @1/2A. The sum of the outputs of the first, w, and second signal generators 34,35 constitutes the bias control signal of the bias control signal generator. By oscillating the rotation of the laser gyro 100 in the forward and reverse directions according to this bias-controlled Th signal, the amplitude of the dither angle was increased alternately by 1/4 (*/2) of the count. , then reduce the difference between the maximum positive dither-negative amplitude and the maximum subsequent dither-negative amplitude to the desired value, 1/2 of the count (π), and then use Equation 1 (ls
)', the equation shown in (11) is satisfied, and the difference in the angle of the sea bream accumulated over the following two Diso cycles is biased so that #l becomes zero.
Control 30 wJ.

An example of the biasing device 30 and coupling element 31 is a spring K and a bolted electrode stone, as shown in 1 US Pat. No. 3,373,650 KB. A pulse is applied to the electromagnet, a torque is applied to the barb, and the laser gyro 10
A dither operation or oscillation is performed in proportion to the magnitude and polarity of the pulse to which zero is applied. The spring-electromagnet system is high 1
Since nQ is shown, when one pulse is applied, several cycles of dither movement are performed. Each pulse is very lightly damped, resulting in nine sinusoidal ringings. When the pulse is combined with a sinusoidally dithered laser gyro, the pulse causes a very lightly damped sinusoidally ringing dither square root at the main dither frequency. The false system that is generated is shown in Figure 95.

Another embodiment of the present invention is shown in the aS diagram illustrating another error cancellation biasing device using the principles of the present invention.

FIG. 5 is similar to the circuit shown in FIG. 3, except that bias signal generator 532 is used instead of bias signal generator 320 in FIG. Second signal generator 35
Bias signal generator 532Fi is similar to bias signal generator 32, except that a pulse generator 537 is used instead. As shown in Figure 1, the 1 pulse generator 537 has an amplitude of
Alternating positive and negative pulses can be generated that are in phase with the main dither signal generated by the dither signal. In FIG. 5a, curve 500 represents the dither movement caused by the signal generated by the first signal generator 34, and curve 510 represents the dithering movement caused by the pulse generated by the pulse generator 537KJJ+. This shows the dithering motion. those two dithers
The dithering motion obtained by combining the motions has an amplitude that is periodically intensified. By suitably shaping the pulses generated by the second signal generator 537, a dithering motion similar to that produced by the biasing device of FIG. 3 is produced. That is, the bias device 30 causes the laser beam 100' to vibrate as shown in FIG. By lifting the dither angle, the amplitude of the dither angle can be alternately increased and decreased by a quarter of a degree. In situations such as +, the desired difference between the maximum positive dither amplitude and the maximum negative dither amplitude will increase, resulting in the difference between the two subsequent dithers. After 11t cycles, it costs $8 and the gyro output angle error is reduced to almost zero.

The above analysis of equations (9) to (18) describes conditions that reduce the accumulated gyro output angle error to approximately zero for a cycle group consisting of V dither cycles. It can be generalized.

For the evaluation that the mathematical expressions in equations (15) and (16) are composed of u dither cycles, (19) I'm here.

In this equation (19), #? is 1tIk: TaserΦ
The maximum positive dither angle amplitude (Kwant) for each individual t1 in the cycle group, θ is the maximum subsequent negative dither angle amplitude (Ff) for the same de1 cycle group.
txt!), B is assumed to be small, and txt! is assumed to be small over M dither cycles. Assuming that it is constant.

(19) Equation (19) indicates that a predetermined value of the maximum positive and negative dither angle widths of a certain dither cycle group that satisfies Equation C19 is determined by , #1 may be the sum of the incremental errors that are zero. For example, if the maximum positive and negative dither angle amplitudes are monotonically and partially increased by a quarter of a quart for each subsequent dither cycle, then 8 dither II+t
-I have more friends than Ikuru! AS becomes zero. As before, in the example, only the one-quarter fractional difference between the subsequent maximum dither-negative amplitudes is at a cost for the triangular chest ampere. Of course, the result of disembarkation is determined by M.
! , plus eight positive maximum dither-negative amplitudes at the zero speed crossing and eight positive maximum dither-negative amplitudes (19
) It is only necessary to satisfy the relationship shown in the formula 6. Therefore, it is not necessary to increase monotonically. Eight positive and negative dither negative amplitudes that satisfy equation (19) can be found from the following equation.

Here, A - a certain amplitude M expressed in quanta, the number of dither cycles in the selected group, 1 a group M
This is the first dither cycle. Therefore, the maximum dither for l# in subsequent dither cycles is
- Given the many possibilities of changing cycles, the cumulative error for each successive dither cycle group is t! It can be used to make it zero.

As mentioned above, # and # in equation (19). As mentioned above, is related to the instantaneous phase difference K[m between two beams traveling in opposite directions during positive and negative successive zero velocity crossings. Therefore, the above considerations demonstrate that the electrical biasing device Kt provides a frequency bias without mechanical rotation.
m used.

It should also be noted that the amplitude used in the above equation is the maximum amplitude of the dither cycle. However, what is more important is when dψ/di is zero and corresponds to near zero sensor input speed around the gyro input axis 26, that is, when the frequency difference is zero and the sign changes. dither
It has a negative amplitude.

The sensor input velocity dψ/dt is the dither motion glass inertial input motion.

Based on the bias device shown in Figs. 3 and 5 and the corresponding analysis by K, Equations (15), (16), (19)
Fully control the maximum positive and negative dither - negative amplitude to meet the maximum positive and negative dither requirements. However, due to the very small perturbations in the subsequent dither cycle pairs, additional errors not included in the mathematical analysis described above are lost.

These perturbations may not be random, but may be the result of selected biasing devices. To make those fluctuations random, 前艷米ai1%#l! f No. 8467
A dual random signal generator similar to that shown in No. 472 may be used. FIG. 6 shows another embodiment of the present invention showing an error cancellation biasing device using the J[Il of the present invention and the inventive OJI principle disclosed in U.S. Pat. No. 3,464,472.

FIG. 6 shows ti!, except that a bias control signal generator 632 is used in place of the bias signal generator 320 shown in FIG. Bias device K11 shown in figure J3
A similar biasing device is shown. Signal generator 340s multi-K12 random amplitude generator 634b in Figure 4 and sine function generation! Bias signal generation 6632 except that a first signal generator 634 comprising 8634m is used.
is similar to bias signal generator 32. The first signal generator 11 produces a sinusoidal function similar to the first signal generator, except that the wave II for each pair of subsequent dither cycles is randomly distributed. First signal generator-3
4, the #Il signal generator 634 can be similarly used in place of the bias device O first signal generator 34 shown in FIG.

In operation, the dither device shown in FIG. 6 dithers the gyro for two dither cycles with some random maximum positive and negative teaser amplitude. The dither negative amplitude is approximately constant except that it is provided by the signal generator of the second dither. The second signal generator is
Two subsequent positive maximum dither-negative amplitudes and two subsequent negative maximum dither angle root $11 $1/2 quanta vary one maximum dither-negative amplitude. Next, the amplitude of the first signal generator 6341 is seen randomly KW,
It is held constant for the next two dither cycles, and so on. In this way, the average error 1iIF resulting from the perturbation of the bias device fK is significantly reduced.
Those errors are made random.

In the above explanation, 1. The laser gyro was assumed to have only a dither sequence and zero inertial input motion.

Here, the sensor input movement around the input axis of the laser gyro is a constant rotation i11 degrees! For a situation in which the laser gyp is subjected to a surface dithering motion that includes a corresponding inertial input motion and the amplitude between two subsequent dithering cycles differs by one-half of a quart as described above. I will think deeply. This situation is illustrated graphically in FIG. In this graph, the base motion is (20)
At a constant rotational speed 111 according to the second direction.

I b= I X 4F4 (20) ζζ,
Fd is the periodically inverted dither-0 frequency 1 ``i'' is the angular increment of inertial input rotation in IK of the quarter of the dither-Φ cycle.

In FIG. 7, the following two maximum positive dither-negative amplitudes can be mathematically described by the following equation.

Ml Tomi +1 + 1-31 (21) M3-M-
)+! +! , where I/C,T is the angular rotation in the middle of the dither cycle. Further, the maximum negative dither amplitude that follows can be expressed by the following equation.

Mu2 = Mu + 4- ” ' (22) Mu4 = A -
--I-31 ρl), by substituting equation (22) into equation (13) and then adding the v4 differences during the two subsequent dither cycles, we get The following formula is obtained for the cumulative error (cut):

th2π(mu-τ+I+1+1)+sh+2π(mu-7-x-g-31)) (23)
From the trigonometry constant, equation (2B) becomes the following equation.

((2)2K(Mu1)-2K(I+g)) (
Audience) C24) Formula is 2 when pace luck wJ exists.
The accumulated error over more than one successive dither cycle is a function of the inertial input motion.

When the base motion is low, it is far superior to the bias device shown in the 3rd, 5th and 6th fusions. On the other hand, when the base motion velocity is relatively high, the error cancellation biasing device of the present invention allows the total look-in error, which is the sum of all Δ−, to increase as the inertia input velocity increases. The reason why high inertial input speeds are undesirable is that they do not take into account the effect of inertial input speed on the eight-loop control of the bias applied by the difference canceling device. .

FIG. 8 shows a schematic diagram of another embodiment of the error cancellation biasing device of the present invention. Jin's embodiment uses closed-loop control. The device shown in No. 8 EK provides bias control of the cap, taking into account the effects of inertial input velocity. In FIG. 8, the laser gyro 100 is connected to the coupling element 3.
1) (to the bias device 30; the bias device sO is controlled by a bias control signal provided by a bias control signal generator 832). angle detector gos combined 1g80
1 and the phase angular velocity detector port 0
This phase angle detector 8G2 always generates a 1 output signal when the phase angle between the light beams of the gyro 100 passes through zero (dφ/at-0). do. Therefore, the output signal is "zero speed crossing"
shows. This "zero speed crossing" is the same as described above.

The output signal of phase angle detector 80G is subjected to multiple processing by error signal element 900. This error signal element 900 is a sample
It includes an ordered circuit H4. This sample bold circuit samples and holds the output value of the 1 phase angle detector 800 at the zero velocity crossing indicated by the phase angular velocity detector 1*0 output signal.

Phase angle velocity detector 802 provides a gate signal to sample bold circuit 804 via coupling element 805 . Error signal element 900 includes a signal processor 81s.

This signal processor 8T5 is a sample/enjoy circuit 804.
The output of the error signal element 900 responsive to the bias output is connected to the bias control signal generator 8 via a coupling element 810.
Given to 32. This bias control signal generator 832
generates a bias control signal in response to a signal applied to it.

Equations (12), (13), which describe the principle of the present invention,
(24), the accumulated gyro output angular error is, assuming that the instantaneous phase angle between the two light beams differs by a selected value of plus or minus π radians at the time of zero velocity crossing. 9. It is stated that the field can be significantly smaller. The closed-loop biasing device shown in Figure 8 applies the principles of the present invention explained in equations (17), (18), and (19) K, and consists of two The value at successive zero crossings of the instantaneous phase angle between the beams has the same polarity as the second derivative -1φ/dt'' and is the n value accumulated over two successive dither cycles or bias reversal cycles. The selected value of plus or minus - radians is chosen so that the twin-in error is zero (the polarity of the second derivative corresponds to the same polarity of the dither angle in the mechanical embodiment). .

Therefore, the four-in-one error contained in the sensor output is significantly reduced to zero. Closed loop control Oj to realize the closed loop bias device shown in FIG.
Shown in the graph of figure. To explain this principle, we will use the IAS device again (mechanical) (IAS device), but electrical) (IAS scissors installation) can be used in the same way. The actuated device is such that the coupling element 31 is one or more leaf springs or other OII-like couplings l! The laser
The gyro 100 is vibrated in the positive direction and in the opposite direction around the gyro input shaft 26, forming a dither motion. Such a system is assumed to be the high Q spring-mass system described above.

Assume that there is a certain input pace movement rate and that there is a certain dither negative amplitude growth rate.

Let the input pace movement speed be the dither cycle IJ)R, and the amplitude growth rate be the dither cycle per fiM.
Kawant. Then, US Patent 1337365
As disclosed in No. 0, a fully sinusoidally dithered gyro has the following maximum and minimum dither negative amplitudes m, /m, , m*/ for -1x2 cycles. Exist throughout.

Mu: l1-3/4 (14M) Mu, wa+1/4 (R-M) Mu, xP+1/4 (RAM) Mu, =N+3/4 (M-1) In particular, %P#N is positive and negative. represents the maximum dither negative amplitude (kakunt) of .

Assume that with Increase the magnitude of these O/< ruses, X and Y, to increase the Iser angle amplitude to x, y*sagaku. this is,/(
As shown in FIG. 9, the situation is very similar to the case where the Iass device is a high-q spring-mass system described above.
The amplitude given to I<Rus X, Y- in synchronization with the two dither cycles is given at point 11 of "+X", that is, at the start of the positive dither cycle, and the amplitude “-X” pulse continues (Year 20 positive disa-
It is given at point 3, which is the start of the fist cycle.

Furthermore, at point 2, which is the start of the negative portion of the first dither cycle, an I (Lemay) with amplitude ``10Y'' is applied, and at the start of the subsequent corner portion of the second dither cycle. A pulse of amplitude r-YJ is applied at point 4.In the high Q spring-mass system described above, in the absence of perturbation or random 'IkII difference, the dither motion is shows the peak amplitude alternating between values 9 that differ by a selected value depending on the thickness of X.
If and Y are chosen appropriately, the instantaneous phase angle between the two beams is 49ψ/d t'' for two subsequent zero velocity crossings of the same polarity (same dither - negative polarity) by a predetermined amount, For example, it is possible to make the difference by 1π radians.

Four successive maximum amplitudes at four successive zero speed crossings! , AltAl'm4 to/<Rusx.

When Y is combined, they are expressed mathematically as follows.

hl=P-3/4(14M)+X As :N+1/4(RM) +X-Y^, =P+
1/4 (14M) + X-Y-X = P + 1/4 (14M)
-YA =N+8/4(M-R)+(X-Y-X+Y
) = N + 3/4 (M - 1) (25) Applying the principles of the present invention, the accumulated gyro output angle errors can be calculated by t can be significantly reduced for one dissipation cycle. The relationship between the maximum amplitude MU and MU*A1#MU40 is MU, FUMU, -1/2 (26° MU, -1/2) Assuming that the above conditions are true, equation (25) can be expressed as x, Solving for yK is x + yzM ten wings + 1 / 2 (27)X
-Y! M-■+172 From this, it becomes x-v+1/2 (28)4.

It should be noted that the amplitudes of pulses X and Y need not have a wide range of variation, since the strength of those pulses can be varied by any integer number of quanta. It is only the decimal part of those kakunts. Therefore, X4! -Y size D-1/2
Power? A range of +1/2 quanta is sufficient.

Next, we convert equation (27) into arbitrary inertial input motion and dither.
Assume that the amplitudes of the pulses X and Y are modulated such that the amplitude of the pulses X and Y is at least one of the following. It remains to determine the appropriate error signal to use to modulate the X and Y pulse generators. Especially %X
Assuming that there is a slope difference between and Y by the amount ``y'' and ry'', equation (28) changes to the following equation.

X = M + 1/2 thousand
==N+3/4 (MR) 10x -y +1/2A
, :P+1/4 (M-am) -y (3
″)) A4-N+3/4 (M-R) is obtained.

As a result, we get . Then, since the modulation errors "x" and "yJ" are introduced, the expression expressed by the (addition) equation is no longer the Hiron expression. (
31) If we take the sine on both sides of the equation, we get 2π(M4-M8)
= Yu2K(x-y) Mu=I or θ+1/8, so (using the equations being equal, Mu=01-1 +1/8 Mu, = 0.10+1/8 m s =Os g + 1/8 m4ζ04 +g+ 1/8.In this ζ, 0□e am # o, * o is 4
represents the instantaneous gyro output phase angle at two consecutive zero speed crossings. Substituting this into (32)2 yields the following equation.

5ia2π(0301)mgb+2g(x+y)1 to 1
2ti04-o2)=yu2g(y-x) Expanding the left side of these equations, we get (dg+2f03)(am2t01)-(am2g03
) (m2ro1) = gk + 21f (x + y) (m2r04) (co + 2r02) - (am2i04)
(slo2r02) f33) Second, to determine the error variables rxJ and ryJ that depend on the sine and cosine values of the instantaneous gyro output phases between the light beams traveling in opposite directions at four successive zero-velocity crossings. The pairwise equation of is obtained. 01 e Om e O, # 04 is detected by the detector 22 as shown in FIG.
It is obtained at the output terminal of 1°22b. Their detected amounts are separated by 174 degrees of interference stripe spacing. This spacing allows one detector to represent the sine value of the instantaneous gyro output phase angle between the light beams and the other detector to represent the cosine value of that phase angle. Of course, one quarter of the interval between the interference stripes
F for the value! There is a certain tolerance difference, which results in a small but negligible error.

Assume now that the output of detector 22ao represents the sine of the phase angle of the two beams, and that the output of detector 22- represents the cosine of that same phase angle. Assume that the output is expressed by the following equation.

In particular, n is the amplitude number 1 at the subsequent zero speed crossing,
2,3.4.

Nominally, M x B, α=β. In particular, m, II represents the gain value of the detectors 22m, 22-, and α, / is 1/4
Represents the phase angle tolerance difference between interference fringes. Here, consider the discriminant functions U, V, -(J, v, and U4v, -U, V4. Since there is no limit on B, α, and β, 8, yυg'q@- 〇1VtkB(*2”(03+α
)(2)2π(Of+β)−gh+2g(01+α)(
2) 2K(03+β)) 8@e=U4V@U, V4=kB(*21K(04
+α) (2) 2π(02+β)−−2π(02+α)(
2) 2g(04+β)) From the trigonometric formula, the right-hand sides of 81 and 8■ are 4th-order K.

81x, iBmb2g (o3-ol) am2g (α
-β) Chapter 8 = ^Blo2π(o4-02)w2π(lα
-β) Therefore, 81-muBw2πCα1β)th2K(o3-01)shamuBas 2K (α-β)*2K(X+F)8 mushrooms=5Bw2g(α-β)*2π(y x )=muB(2
)2π(α-β)gln2π(y-x)Here, if 1y and . Here, K=2π^B(2)2π
(α−β). Therefore, x= (81-8= ) / 2 K F" (L + 8! ) / 2. Since X and y represent the errors in X and Y, er
7) Keep both the left and right sides expressed by the equation correct, and set the correct pulse amplitude X so that the gyro output angle difference accumulated over two subsequent dither cycles is approximately zero
To obtain Y9h6KFiX, we must subtract r and y from y respectively, i.e., X' = X x = X-(8,-8s)
/2KY'= Y y= Y-(L-Hz)
/2 This means that for a signal with zero error, X and y#
i is kept constant, otherwise x, y is used to modulate the pulse amplitude x, y as commanded by the error signal.
means that it is modified by adding the increment x, y) and subtracting the increment.

The error signals S1 and 81 are triangular multilevel ambiguity trIgo
nom@tr lc multivalue ambl
Please note that the term ``gulty''. That is,
When the two amplitudes (01 and 01 in the case of 81, and 04 and 0. in the case of 8°) differ by 1/2 quant, the error signal is not trivial; Even when they are equal, there is no error signal. In other words, the zero difference signal for Xml is also fed back with an error of 172 counts. Therefore, it is sometimes necessary to increase the error signal by 1/2 quart. This ambiguity is explained by another analog meter x'
That is, Gw(J□+U@+V1+Va1(==[J,
+[J4+ V, +V4G exceeds a certain threshold value (for example, G>1/2(^+B)) Add 1/2 kawant to s, and if 1H exceeds a certain threshold value, 8 m K ” Add 1/2 kacunto.

FIG. 1.theta. is a more detailed block diagram of a closed loop error cancellation biasing device employing the principles of the present invention than in FIG. This closed loop error 1 cancellation bias &if operates in the same way as the bias device shown in FIG. 8, and #! Utilizing the control method described with reference to FIG. Assume an electropattern biasing device exhibiting a high spring-mass system.

In FIG. 10, ring laser e-gyro 800 is laterally biased from biasing device 30 through coupling 11I element 31. In FIG. The bias device [31t] is controlled by a bias control signal provided from a bias control signal generator 832. 10th FkJO closed loop bias device 10
includes error signal generation 1ssoo.

The error signal generator 900 biases the error signal to the control signal generator 83? in response to the gyro output phase angle relationship between the two beams traveling in opposite directions. -Give. This completes the closed loop control system.

The bias #IJ control signal generator 832 includes an adder 836;
It consists of an X pulse generator 835 and a Y pulse generator &837. Adder 8311a adds the output signals from signal generator 834, similar to first signal generator 34 of FIG. X/<Russ generator 83 connection Y pulse generator 8
37 generates a pulse signal. These pulse signals are added to the output signal of the dizer signal generator 834 by a summer 836. The output of summer 836 is the bias damping signal from bias control signal generator $32 and is applied to via lateral 30.

Bias signal generator 832 receives an error signal from error signal generator S@. This Ow4 difference signal generation aso.

is a signal processor 875 and a sample/hold game) 8
04m, 804b and signal storage device 807m, 807k
including. The signal processor 815 processes phase angle data in response to the gyro output phase angle between two oppositely different light beams, and outputs an output error signal χ that modulates the X pulse generator 835 and the Y pulse. Generates an error signal y that modulates a generator 831.

The biasing device of FIG. 10, like the biasing device shown in FIG. 8, requires a value of the phase angle φ of two light beams traveling in opposite directions IK at approximately zero velocity crossing. Furthermore, the control method used in the apparatus of FIG.
Use the sine and cosine values of the phase angle that correspond to the zero speed crossing. In FIG. 40, a laser gyro 800 similar to laser gyro 100 (FIG. 1) includes a photodetector 22ae2.
2b is provided. The photodetectors 22ae and 22b are spaced apart from each other by a distance of 1/4 of the distance between the interference trench patterns.
A phase angle detector is constructed that generates signals indicative of the sine and cosine of the phase angle between the two beams. The output terminal of the photodetector 22m is coupled to the window comparator 841 via the time differentiation circuit 845, and the output terminal of the photodetector 22 is connected to the time differentiation circuit 845.
45b coupled to window comparison 843.

The output terminals of these window comparators are logically coupled to an AND circuit 844. Window Hikini 41841, 843% differentiator 845a and 845 bs and AND-gate circuit 8
44 is a phase angular velocity detector 8020 shown in Figure 8.
perform a function.

As shown in FIG. 10, the error signal generator SOO
The sample and hold circuits 1104m and 804 are gate-controlled by the output of an AND gate 844. The output of the photodetector 220 is applied to the sample bold circuit 804m, and the output of the photodetector 22b is applied to the sample bold circuit 804b. The output of each sample bold circuit 804, 804b is stored in temporary storage 80.
7 a p 80 T k each and knead. Their sample bold circuits and temporary storage can be analog, digital, or a combination thereof;
Here for 1 Ming, a sample bold circuit 110
4m, 804b It will be considered as a digital representation of the output company photodetection age 22a*22b. Storage device 807m,
It is assumed that 807b is a normal digital memory circuit.

The outputs of the temporary storage devices 807m and 8G7b are processed by the signal processor 875 of the bait difference signal generator. The signal processor 875 performs the calculation described above using equation (25) in order to output an output control error signal indicating X and y in (25 stages). Generator 8
35 and Y pulse generator 837, respectively. The error signal X,7 is generated by the X pulse generator 83 as described above.
5 and Y pulse generator 831, respectively.

Since window comparators 841 and 843 are similar to each other, window comparator 841 will be explained. Illustrated in FIG. 10a is one embodiment for constructing a window comparator. 10th
Referring to figure a, window comparator $41 is connected to comparators 842a and 842a.
42b. Comparator 842m.

842b is used as a simple comparator to compare the levels of the two signals and can be a conventional operational amplifier or other device. The output terminal of the differentiator 8451 is connected to the positive input terminal of the saddle device 842a. Differentiator 845
Output line comparator 1142 of a! It is also connected to the inverting input terminal of I. The inverting input terminal of the comparator 842b has a reference voltage of 1"
+'K41 is connected, and the non-inverting input terminal of the comparator 842- is connected to the reference voltage r-JK.Comparators 842m, 842
The output of b is combined with the Noah game) 114@.

Next, the operation of the one-window comparator 841 will be explained. As long as there is a constantly changing phase of sufficient velocity (dφ/dt) between the light beams, the phase differentiator 845aO output can be positive or negative and its magnitude is a sufficiently small amount C. A pre-selected value such as 〕Turtle is large. In this situation, the output of one (but not both) of comparators 12 and 842 is a logic 1 (high voltage level corresponding to IJ).The output of NOR gate 84s is a logic 0 in this situation. (rOJ). On the other hand, while the zero speed crossing dψ/dt is zero, the output of the differentiator 8451 decreases to a value lower than the positive or negative value of e, and the output of the comparator 8451 decreases to a value lower than the positive or negative value of e.
The output lines to 42a and 842 become "0". In this situation, the output of NOR gate 210 is "1".

The window comparator 843 is connected to the output terminal of the phase differentiator 845b. This window comparator 843 performs the same operation as described for the window comparator 843 in response to the output of the photodetector 22m. That is, when the rate of change of the phase angle between the light beams is higher than the threshold value of the window comparator, the output of the window comparator 843 is always K "0"], and the rate of change of the phase angle is higher than the threshold value. C
When it is low, it is "1".

Next, the operation of the closed loop bias device shown in FIG. 1 will be explained. The photodetectors 22as22b are arranged at a distance of about 174 times the distance between the interference fringe patterns. The output of photodetector 22& can be thought of as the sine of the phase angle between two light beams traveling in opposite directions, and the output of photodetector 22 represents the cosine of the phase angle between the same light beams. You can think about it.

At the zero speed crossing, the output of comparator 141, 843 is "1". The reason is that the time cost ratio of the phase angle is zero, so the value is between +1 and -6. In this situation, since each output of the window comparators 841 and 848 is rlJ, the output of the Antogedro 44 is "l".
However, in all other situations, the output of the AND gate 44 is rOJ, which performs a constantly applied dithering motion, as the output of the AND gate 844 changes from ``0'' to ``L''.
sample bold circuit 804a, 11
04b is gated and whatever is applied to its input terminal is sampled and held temporarily until the next gate, which occurs at the next zero speed crossing. Thus, the sample-and-prison circuit represents the sine and cosine, respectively, of the phase angle between the light beams at photodetector 22a when each zero velocity crossing occurs.

A photodetector 22ae22b samples the output of the detector 22b.

The outputs of the sample and jail circuits 804m, 8041+ are stored in the storage devices 807a, 80rbK, and then processed appropriately by the signal processor 900.

The signal processor 900 combines the instantaneous phase angles from the photodetectors 22a*22b at subsequent zero velocity crossings to obtain (
34) Apply pressure as described with reference to equations to provide output control differential signals X and y. The signal processor 815 uses the formula c)K
The signal processing device 13 can be used as long as it can perform arithmetic operations such as those described in connection with the solution of the simultaneous sleep formula i.
7B can be used in both analog and digital formats.

Continuing with the discussion, it is important to identify the "dominance" of subsequent zero velocity crossings in relation to the instantaneous phase angle during each portion of the dither cycle between two beams traveling in opposite directions. Hereinafter, successive positive zero speed crossings will be referred to as zero speed crossings where dlφ/dll is positive,
d1φ/dt'' is negative. In a mechanical bias device, positive and negative zero speed crossings are when the direction of rotation changes from the first direction to the second direction. and the time at which the direction of rotation changes from the second direction to the first direction, respectively.Referring to FIG.
．． 5 sK, and the subsequent negative zero speed crossings correspond to dither negative amplitudes M1 and M4.

At this point, there is no inertial input motion and the bias control signal generator 1132 provides a bias control signal to the bias device 3° for each of two subsequent zero speed crossings of the same sign (i.e.
positive or negative zero-velocity crossing) k such that the instantaneous phase angles between the two beams at K differ by exactly one-half quart, or ±π Kudian. In the current situation, the output signals x, y are zero and To], the X pulse generator 83s and the Y pulse generator 837 are constant 11, referring to 3rd g,
The 311th case where the cumulative gyro output angle error is zero
behaves as described above for expressions related to .

We will now discuss the response of the closed loop biasing device shown in FIG. 1O in situations where there is some inertial input motion within the device shown in FIG. 1O. In this situation, the instantaneous phase angles between two successive zero-velocity crossings of the same sign no longer differ by radians. In this situation, the signal processor sOO is
! Since the appropriate X and y signal values are quickly provided to modulate the X value of S and the value of Y pulse generator 8370y, the X and y values are again zeroed. Therefore, the rules are such that the t-phase angles between the light beams for successive zero velocity crossings of the same sign differ by ±π radians and the total error accumulated over two dither cycles is zero.
X and 1 provide the closed loop error signal needed to operate the gyro's rounding bias system in closed loop mode. Of course, this is the sensor output Ki! ! This means that the lock-in error caused by 1 is also reduced to almost zero.

The control technique described in (25) and illustrated in the embodiment shown in FIG. It should be noted that this is only one example of the various control techniques that can be used.

- difference signal generator 900 and bias control signal generator 832;
The combination with the beak of the watch g1shi, which happened previously,
The instantaneous phase angles must be controlled based on the instantaneous phase angle at the dither angle and the instantaneous phase angle at the counterclockwise beak dither angle. The error signal generator 900 and the nine control metrics tc and the subsequent zero speed crossing values are such that the lock-in error in the output signal typically associated with a ring laser sensor 900 is significantly reduced (19). It can have a predetermined value according to 2. Furthermore, although one or more of the described embodiments have been described using mechanically biased contact, electrical/optical techniques, as described above, may also be used to reduce lock-in errors. Although the lock-in error reduction described above uses zero velocity cross phase angle information, other selected phase velocity points can also be selected. This is within the scope of the invention.

[Brief explanation of the drawing]

Fig. 1 is a diagram of a conventional ring laser angular velocity sensor, Fig. 1a is a diagram of an example of a phase angle detector used in the sensor of Fig. 1, and Fig. 211 is a diagram of a dithered sensor.
A graph showing the relationship between angle and time; FIG. 3 is a block diagram of an embodiment of the present invention; FIG. 4 is a block diagram of an example; FIG. 7 is a graph of dither angle versus time pixel inertial input motion; FIG. 11 is a detailed block diagram of a closed loop feedback biasing device employing the principles of the present invention; and FIG. 11 is a grab of the lock-in error inherent in a sensor of the type shown in FIG. 30...Bias device, 32,532,632°832...Bias control signal generator, 34.35.
... Signal generator, 537 ... Pulse generator, 63
4...Random amplitude generator, 800...Phase angle detector, 802...Phase angular velocity detector, 804@...
- Gun sample 11 indicator circuit, 875... Signal processor, 841, 843... Fist/window comparator. Patent applicant: Honeywell, Inc., sub-agent Masaki Yamakawa (and one other person) Engraving of drawings (no changes to the content) Itch, 2 Fte:;, 4 Fta, 5 Ftcy, 6 Ftcy, 9 Ftc; 11 FtO, θ Commissioner of the Patent Office NN *57. Right, 13
81, Indication of the case 1999 patent application No. 11'7G33 2, all EIFI
3. Relationship with the case of the person making the amendment Date of the patent applicant
Showa Town, October 6th, 2019 - Subject of G4 correction, drawing 41

Claims (1)

[Scope of Claims] (1) There is an angular velocity sensor in which two tIts move in opposite directions along a closed loop path in alternate layers, and the frequency of the combined wave is the lI number of the rotational speed of the closed loop path. Yes, there is a phase separation S between the waves that is a function of the rotation speed of the closed-loop path, and the sensor has a lock-in error that is related to the true rotation angle of the sensor but is inherent to the sensor. The first sen containing? In the angular velocity sensor that generates the wave, the phase φ of the phase relationship between the waves is dφ/dt
%1 when the selected value occurs.
So that the 11th value and the 20th value are taken alternately (and 4l-)
An angular velocity sensor characterized by being equipped with a bias device capable of distributing waves before zero. (It is an angular velocity sensor in which two tIts move in opposite directions to P! along a closed loop path, and the frequency of the combined wave is the a movement of the rotational speed of the closed loop path, and the interval between the waves is has a phase relationship that is a function of the rotational speed of the closed-loop path, and the sensor generates a sensor signal #l that is related to the true rotation angle of the sensor but includes a lock-in error that is inherent to the sensor. said angular velocity sensor (having a terminal adapted to receive an IAS control signal) for changing the frequency of at least one said wave;
dφ/dt is zero, and the phase of the phase M coefficient between the waves is d"94?/di.
The bias device is capable of controlling the bias device and the control signal “IAS” so as to take the first and second values alternately when the corresponding values of “IAS” are of the same polarity. The bias signal generator generates at least one previous i-wave such that the frequency difference between the waves varies periodically at a first frequency. a first signal generator for generating a first signal for periodically varying the frequency; and at least one signal generator for generating a first signal for periodically varying the frequency of the waves; a second signal generator that generates a first signal to periodically oscillate the frequency of the wave; and a second signal generator that adds the first signal and the second signal to generate the bias control signal. an adder, and the bias device includes a selected #L of dφ/di.
occurs, the running time is selected, and the phase alternately takes the first value and the second value when running, and the bias is set so that the OVa gain in the first Senna signal is made sufficiently small. An improved angular velocity sensor, wherein the device is characterized by a human acting on the phase in response to the piezoelectric control signal. (a supporting element supporting two nearly single-frequency electromagnetic radiation beams that can travel #trt around a closed-loop path and passing #C in opposite directions, a phase angle detector, and a bias and a bias control signal generator, the frequency of the multiplexing is equal to the ra number of the rotational speed of the closed loop path,
There is a phase relationship between the waves that is a function of the rotation speed of the closed loop path, and the phase angle detector loses at least one output signal related to the phase ψ of the phase relationship between the waves O. Similarly, the biasing device can envy the phase φ of the phase relationship, and controlling the biasing device so that the phase takes a phase value related to the control signal at a selected nine value of dφ/dt. The first bias device # has a terminal element adapted to receive a bias control signal for
The bias control signal generation device generates the bias control signal in response to at least one output signal of the phase angle detector, and the bias control signal generator generates at least one of the bias control signals. In response to two output signals, dψ
a first element determining a first phase value of said phase when a first selected value of /dt occurs; and a second element of dφ/di.
The control signal causes the biasing device to generate a second phase angle value of the phase the next time the selected value of is generated such that the first phase value and the second phase value are a second element that determines the bias control signal in response to the first phase value so as to differ by a predetermined value. (4) The 8th circle of the closed loop path is t! Two mutually oppositely traveling beams that can proceed are interference generated by a supporting element supporting a beam of electromagnetic radiation of a single frequency and an optically combining part of said two beams. a phase angle detector including first and second transducers generating an output signal in response to the pattern and a selected phase difference in response to the output signals of the first and second transducers; The mansion and dφ
at least a first error related to the difference between the actual phase difference of the first and second magnitude of said phase when the selected values of /di are generated the first and second times '31 successively; an error signal element that generates a signal; and a bias control signal generator that generates the bias control signal in response to the first error signal, the frequency of the combined wave being equal to the rotational speed of the closed loop path. yIJ several degrees Celsius, there exists a phase relationship where the function Ka of the waves is a function of the rotation speed of the closed loop path, and the $1. !
- each second transducer is responsive to a different part of said interference pattern, and each transducer of prearrangement I and Fukushi 2 is related to the phase of said phase relationship between said waves but with a predetermined measured phase offset; the bias control signal generator has output signals that differ by a first
a first signal generating a first signal for periodically varying said frequency of at least one said wave so as to vary at a frequency of
a pulse orderer of Ml that generates an output signal that is a pulse of electrical energy of alternating polarity in temporal relation to a selected value of dψ/di; and of said first signal element) 1! an adder for generating the bias control signal by adding the signal of 1 and the output signal of the first pulse generator, the first pulse generator being related to the error signal of the preposition 1; The biasing device acts on the phase in response to the bias control signal such that the phase has a magnitude of energy and the phase assumes first and second values that differ by the selected phase difference. 4. Laser angular velocity sensor◎゛