KR20110072316A - Method and apparatus for compensating phase error of ring laser gyro - Google Patents

Abstract

PURPOSE: A method and an apparatus for compensating a phase error of a ring laser gyroscope are provided to improve the operating reliability of a gyroscope by using phase error compensation algorithm. CONSTITUTION: A method for compensating a phase error of a ring laser gyroscope is as follows. An output signal of a gyroscope(101) is changed into the square wave signal. An edge is detected from the square wave signal. The time of the detected edge is measured and stored. A phase error is calculated from the measured edge time. A phase error of the output signal is compensated using the calculated phase error.

Description

Phase error compensation method of a ring laser gyroscope and an apparatus therefor {Method and apparatus for compensating phase error of ring laser gyro}

The present embodiment relates to a ring laser gyroscope, and more particularly, to a phase error compensation method of a ring laser gyroscope and an apparatus therefor.

The ring laser gyroscope allows the laser beams to travel in opposite directions, for example clockwise and counterclockwise, simultaneously in a resonator of three or more reflectors, and the frequency of these laser beams causes the gyroscope to rotate externally. It depends on the rotational angular velocity at the time, and it is a device for measuring the rotational angle (or rotational angular velocity) by detecting the difference of the frequency, that is, the phase difference.

The output of such a ring laser gyroscope appears in the form of a sin curve, and the frequency of the sinusoid curve changes according to the magnitude of the external rotational input. However, when the size of the external rotation input is small, a lock-in effect occurs in which the frequencies of the two laser beams are equal to each other due to the backscatter of the reflector, and this occurs when the size of the rotation input is below a certain threshold. There is a problem that gyroscope measurement is impossible.

To solve this problem, the body vibration of the sine wave is applied to the gyroscope, which causes the output of the gyroscope to appear in the form of a sinusoidal curve that periodically passes through the lock-in period. This lock-in period causes a phase change before and after the direction change of the gyroscope, and this phase change causes the gyroscope to malfunction.

Conventionally, a phase is calculated using a second-order curve curve fitting on the half-cycle frequency variation in the output signal of the gyroscope appearing before the turning point of the sinusoidal body vibration, and the output signal of the gyroscope appearing after the turning point. After calculating the phase using the half-cycle frequency change, a method of estimating the phase change in the lock-in period by comparing the calculated phases before and after the change of direction is used.

However, in the conventional phase change estimation method, the phase error is estimated to be smaller or greater than the actual phase error according to the operation state of the gyroscope. This reduces the operation reliability of the gyroscope.

The problem to be solved by the present invention is to improve the performance of the gyroscope by providing a method that can compensate for the phase error of the ring laser gyroscope.

Another object of the present invention is to provide an apparatus for performing a phase error compensation method.

The phase error compensation method of the ring laser gyroscope according to an embodiment of the present invention for solving the above problems, converting the output signal of the gyroscope into a square wave signal, detecting the edge from the square wave signal, Measuring and storing the time, calculating the phase error using the measured edge time, and correcting the phase error of the output signal using the calculated phase error.

According to an aspect of the present invention, there is provided a phase error compensating apparatus for correcting a phase error of an output signal according to a signal processing circuit for calculating a phase error from an output signal of a gyroscope and a calculated phase error. It includes an error correction unit.

According to the method and apparatus for compensating the phase error of a ring laser gyroscope according to the present invention, the phase error in the lock-in period caused by the sinusoidal body vibration of the gyroscope is estimated by calculating the time-phase area of the output signal of the gyroscope. By using the phase error compensation algorithm that compensates for the phase error of the output signal, the operation reliability of the gyroscope can be improved.

In order to fully understand the present invention, the operational advantages of the present invention, and the objects achieved by the embodiments of the present invention, reference should be made to the accompanying drawings that illustrate embodiments of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Like reference numerals in the drawings denote like elements.

1 is a schematic block diagram of a phase error compensator of a gyroscope for compensating for a phase error according to an embodiment of the present invention.

Referring to FIG. 1, the phase error compensator 100 includes a gyroscope 101, a signal processing circuit 103, and an error compensator 105.

The gyroscope 101 includes four reflectors 111 and two light detectors 113 and a relative angular velocity sensor (RAVS) 115.

The four reflectors 111 reflect two traveling waves traveling in opposite directions in the gyroscope 101.

Each of the two light detectors 113 may be located in one of the four reflectors 111, and detects the output of the gyroscope 101 reflected by the four reflectors 111 to detect two detection signals ( PDS1, PDS2) are output.

In some cases, a coupling prism (not shown) may be further disposed between one reflector and two light detectors 113.

The relative angular velocity sensor 115 senses the behavior of the gyroscope 101 and outputs a sensing signal, that is, an angular velocity signal DTHR.

The two detection signals PDS1 and PDS2 and the angular velocity signal DTHR output from the gyroscope 101 are input to the signal processing circuit 103.

The signal processing circuit 103 estimates and outputs the phase error ψ _e of the gyroscope 101 from the two detection signals PDS1 and PDS2.

The signal processing circuit 103 also outputs a control signal IRQ for controlling the operation of the phase error calculator 145 of the signal processing circuit 103 from the angular velocity signal DTHR.

The signal processing circuit 103 includes a first signal processor 120 and a second signal processor 140.

2 is a schematic block diagram of the first signal processor illustrated in FIG. 1, and FIG. 3 is a signal waveform diagram according to an operation of the first signal processor.

1 to 3, the first signal processing unit 120 of the signal processing circuit 103 receives the first detection signal PDS1 from one of two optical detectors 113 of the gyroscope 101. A first circuit 121 for outputting the first square wave signal sinP and a second detection signal PDS2 received from the other of the two optical detectors 113 to output the second square wave signal cosP. And a second circuit 125 and a third circuit 127 that receives the angular velocity signal DTHR from the relative angular velocity sensor 115 and outputs a third square wave signal DTHZR.

Each of the first circuit 121, the second circuit 125, and the third circuit 127 is an amplifier 131, 134, 137, a comparator 132, 135, 138, and a glitch remover 133, 136, 139).

The first amplifier 131 of the first circuit 121 amplifies and outputs the first detection signal PDS1. The first detection signal PDS1 may be a current signal, and the amplified first detection signal PDS1 ′ may be a voltage signal.

The first comparator 131 of the first circuit 121 compares the amplified first detection signal PDS1 ′ with the reference level Ref and outputs a first square wave signal sinP according to the comparison result.

Here, when the amplified first detection signal PDS1 ′ is a voltage signal, the reference level Ref may be a voltage value of zero.

For example, the first comparator 131 may adjust the first level (eg, the high level) when the amplified first detection signal PDS1 ′ is greater than the reference level Ref, that is, a positive level. The branch outputs the first square wave signal sinP.

In addition, the first comparator 131 has a first level having a second level (eg, a low level) when the amplified first detection signal PDS1 ′ is smaller than a reference level Ref, that is, a level of (−). Output a square wave signal sinP.

That is, the first comparator 131 compares the amplified first detection signal PDS1 ′ with the reference level Ref, and accordingly, the first square wave signal sinP in which the first level and the second level appear alternately. Outputs

The second amplifier 134 of the second circuit 125 is the same as the first amplifier 131 of the first circuit 121 except for receiving and amplifying the second detection signal PDS2 as an input. .

Similarly, the second detection signal PDS2 may be a current signal, and the second detection signal PDS2 'amplified by the second amplifier 134 may be a voltage signal.

Also, the second comparator 135 is the same as the first comparator 131 except for comparing the amplified second detection signal PDS2 ′ with the reference level Ref to output a second square wave signal cosP. Do.

Here, the first square wave signal sinP output from the first circuit 121 and the second square wave signal cosP output from the second circuit 125 may have a phase difference of π / 2. This is because the first detection signal PDS1 and the second detection signal PDS2 output from the gyroscope 101 have a phase difference of π / 2.

In addition, the third amplifier 137 of the third circuit 127 is the same as the first amplifier 131 of the first circuit 121 except for receiving and amplifying the angular velocity signal DTHR as an input.

Similarly, the angular velocity signal DTHR may be a current signal, and the angular velocity signal DTHR ′ amplified by the third amplifier 137 may be a voltage signal.

In addition, the third comparator 138 is the same as the first comparator 131 except that the third square wave signal DTHZR is output by comparing the amplified angular velocity signal DTHR ′ and the reference level Ref.

Meanwhile, the glitch removers 133, 136, and 139 illustrated in FIG. 2 are comparators of the first circuit 121, the second circuit 125, and the third circuit 127. The first square wave signal sinp, the second square wave signal cosP, and the third square wave signal DTHZR output from the second comparator 135 and the third comparator 138 may be removed.

In addition, according to various embodiments of the present disclosure, the glitch removers 133, 136, and 139 may be located in the second signal processing circuit 140 to be described later, or may be omitted in some cases.

In addition, although not shown in the drawings, a delay generator (not shown) may be further included at the rear ends of the glitch removers 133, 136, and 139, respectively.

4 is a schematic block diagram of the second signal processor illustrated in FIG. 1, and FIGS. 5 and 6 are signal waveform diagrams illustrating operations of the second signal processor.

1 and 4 to 6, the second signal processor 140 may include an edge detector 141, a storage 143, a phase error calculator 145, a first pulse counter 146, and a first pulse counter 146. And a two pulse counting unit 147, a first timer 142, and a second timer 144.

The edge detector 141 detects a plurality of edges RE and FE from the first square wave signal sinP output from the first signal processor 120.

Here, the plurality of rising edges (hereinafter referred to as RE and falling edges (hereinafter referred to as FE)) may refer to a portion where a level is shifted in the first square wave signal sinP, for example, a plurality of rising edges RE and a plurality of rising edges RE. And a falling edge FE.

The edge detector 141 may output an edge time ET for each of the plurality of detected edges RE and FE. For this purpose, the first timer 142 sends the time t to the edge detector 141. To provide.

For example, the first timer 142 provides the edge detector 141 with a time t during the operation of the phase error compensator 100.

The edge detector 141 generates an interrupt at a time t provided from the first timer 142 by using the plurality of edges RE and FE detected from the first square wave signal sinP, respectively. The edge time ET can be measured.

The measured number of edge times ET is provided to and stored in the storage 143.

The storage unit 143 stores a plurality of edge times ET provided from the edge detector 141.

The storage unit 143 stores a plurality of edge times ET in a first time domain and a second time domain according to the third square wave signal DTHZR output from the third circuit 127 of the first signal processor 120. Can be classified and stored as.

For example, the storage unit 143 may set the edge times ET1 and the direction change reference point before the direction change reference point according to the third square wave signal DTHZR output from the third circuit 127. The data is classified and stored according to the later edge time ET1.

The first pulse counting unit 146 is also called a quadrature encoder pulse (QEP) circuit, and counts a count signal from the first square wave signal sinP and the second square wave signal cosP output from the first signal processing unit 120. Outputs CS). The count signal CS is provided to the error correction unit 105 to be described later.

The second pulse counter 147 counts the number of times zero-crossing of the first square wave signal sinP occurs after zero-crossing of the third square wave signal DTHR and according to the counting result. Output a control signal IRQ.

The control signal IRQ is output to the phase error calculator 145 to control its operation.

The phase error calculator 145 calculates and outputs a phase error ψ _e from the output of the gyroscope 101 output at a predetermined time by the second timer 134, that is, the first detection signal PDS1. .

The phase error calculator 145 receives a plurality of edge times ET1 and ET2 from the storage unit 143 according to the control signal IRQ output from the second pulse counter 147, and detects the first detection time. The phase error ψ _e may be calculated from the first detection signal PDS1 mapped to the signal PDS1 and mapped with the edge time.

The phase error calculator 145 estimates the estimated signal ES from the first detection signal PDS1.

For example, the first detection signal PDS1 output from the gyroscope 101 may be represented by Equation 1 below.

In addition, the phase error ψ _e calculated from the phase error calculator 145 may be represented by Equation 2 below.

Here, K _scf is a proportional constant of phase and angular velocity, Ω _L is a lock-in region threshold [deg / sec], and β is an initial phase coefficient.

The phase error calculator 145 calculates the phase error ψ _e by using the plurality of edge times ET1 and ET2 output from the storage unit 143 together with [Equation 1] and [Equation 2]. The phase error ψ _e may be calculated by calculating an edge time-specific area of the estimated signal ES estimated from the first detection signal PDS1.

In this case, the phase error calculator 145 may calculate a phase error ψ _e in an adjacent section of the direction change reference point of the gyroscope 101, which is a phase error ψ _e of the gyroscope 101. This is because it occurs near the reference point.

The phase error calculator 145 performs an edge time of an adjacent section of the direction change reference point to among the plurality of edge times ET1 and ET2, for example, the edge times t ₁ , t ₂ , and t ₋₁ shown in FIG. 5. And substituting t ₋₂ into [Equation 2] to calculate edge hourly areas S ₁ , S ₀ , S _{_1} .

The area for each edge time may be represented by Equation 3 below.

Here, t ₀ is an intermediate value (or an average value) between t ₁ and t ₋₁ , and ψ ₀ represents the phase of the gyroscope at t ₀ .

t ₀ may be represented by Equation 4 below.

In order to calculate ψ ₀ , a system of equations using t ₁ , t ₂ , t _-1, and t _-2 can be represented by Equation 5 below, and ψ ₀ can be represented by Equation 6 according to Equation 5. ]

The median value of the phase error computation unit 145, the intermediate value and the direction conversion calculated area after the reference point (S _{_1)} in the direction change control point phase error, i.e., the calculated surface area (S ₁₎ before as shown in Figure 6 it is possible to calculate the phase error (ψ _e) of the difference, the phase error (ψ _e) can be represented by [equation 7] below.

The IES signal illustrated in FIG. 6 may be a signal obtained by integrating an ES signal.

Referring back to FIG. 1, the phase error ψ _e calculated by the signal processing circuit 103 is output to the error correcting unit 105.

The error correction unit 105 accumulates the phase error ψ _e outputted from the signal processing circuit 103 for a predetermined time, and uses the accumulated phase error ψ _e to phase out the output signal of the gyroscope 101. Correct the error.

For example, the second signal processing unit 140 of the signal processing circuit 103 may use the first pulse counting unit 146 to output the gyroscope 101, for example, the first square wave signal sinP and the second square wave. A counting operation, that is, a counting operation, may be performed from the phase change of the signal cosP, and accordingly, the counting signal CS may be output.

Here, when the first pulse counting unit 146 performs a counting operation using one of the first square wave signal sinP and the second square wave signal cosP, the phase of the one signal changes by π. Can count one pulse.

In addition, when the first pulse counting unit 146 performs a counting operation using both the first square wave signal sinP and the second square wave signal cosP, when the two signals are out of phase by π / 2, Pulses can be counted.

At this time, if the phase error ψ _e accumulated and stored in the error correcting unit 105 increases or decreases and changes by π / 2 or π, the error correcting unit 105 changes the gyroscope according to the count signal CS. It may be determined that an error of one pulse has occurred in the output signal of 101).

The error correction unit 105 compensates the phase error ψ _e of the output signal of the gyroscope 101 by adding or subtracting one pulse to the output signal of the gyroscope 101.

Although the contents of the present invention have been described with reference to the embodiments shown in the drawings, these are merely exemplary and will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. . Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS In order to better understand the drawings cited in the detailed description of the invention, a brief description of each drawing is provided.

1 is a schematic block diagram of a phase error compensator of a gyroscope for compensating for a phase error according to an embodiment of the present invention.

FIG. 2 is a schematic block diagram of the first signal processor illustrated in FIG. 1.

3 is a signal waveform diagram illustrating an operation of the first signal processor.

4 is a schematic block diagram of the second signal processor illustrated in FIG. 1.

5 and 6 are signal waveform diagrams illustrating operations of the second signal processor.

Claims (8)

Converting the output signal of the gyroscope into a square wave signal; Detecting an edge from the square wave signal, and measuring and storing a time of the detected edge; And Calculating a phase error using the measured edge time, and correcting a phase error of the output signal using the calculated phase error. The method according to claim 1, The output signal includes a first signal and a second signal of different phases, Converting the output signal into a square wave signal, Amplifying the first signal and the second signal, respectively, and comparing each of the amplified first and amplified second signals with a reference level; And Generating and outputting a first square wave signal from the first signal according to a result of the comparison, and generating and outputting a second square wave signal from the second signal. The method according to claim 2, And a phase difference of π / 2 between the first signal and the second signal or the first square wave signal and the second square wave signal. The method according to claim 1, Detecting an edge from the square wave signal, and measuring and storing the time of the detected edge, Detecting the edge from the square wave signal and generating an interrupt using the detected edge at a time provided from a timer; And A method for compensating for phase error of a gyroscope comprising measuring and storing a time at an interrupt occurrence time as an edge time. The method according to claim 4, The measuring and storing of the edge time may further include classifying and storing the edge time before and after a direction change point according to a direction change reference point. The method according to claim 1, Calculating a phase error using the measured edge time, Equation from the output signal

Estimating a signal using the signal and mapping the measured edge time to an estimated signal; And Compute and accumulate the phase error by calculating the area for each edge time from the estimated signal to which edge time is mapped, and calculate the difference between the median values of the area for each edge time calculated before / after the direction change point of the estimated signal. A phase error compensation method of a gyroscope comprising calculating and accumulating as an error. Here, K _scf is a relationship constant between phase and angular velocity, Ω _L is an error phase, and β is an initial phase coefficient. The method according to claim 6, Compensating the phase error of the output signal, A gyro for determining a time point at which the accumulated phase error changes by π / 2 or π from the phase of the output signal, and adding or subtracting one pulse from the coefficient value of the output signal to compensate for the phase error of the output signal. How to compensate for phase error in the scope. A phase error compensation device for correcting a phase error from an output signal of a gyroscope, A signal processing circuit for calculating a phase error from the output signal of the gyroscope; And An error correction unit for correcting a phase error of the output signal according to the calculated phase error, The signal processing circuit, A first signal processor converting the output signal into a square wave signal and outputting the square wave signal; And And a second signal processor for measuring an edge from the square wave signal and calculating the phase error using the measured edge.

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