CN110926448B

CN110926448B - Method for judging falling edge of triggering square wave of fiber-optic gyroscope

Info

Publication number: CN110926448B
Application number: CN201911304669.9A
Authority: CN
Inventors: 李光辉
Original assignee: Chongqing Huayu Electric Instrument Group Co Ltd
Current assignee: Chongqing Huayu Electric Instrument Group Co Ltd
Priority date: 2019-12-17
Filing date: 2019-12-17
Publication date: 2023-03-10
Anticipated expiration: 2039-12-17
Also published as: CN110926448A

Abstract

The invention discloses a method for judging the falling edge of a triggering square wave of a fiber-optic gyroscope, which comprises the following steps: 1) Sampling the trigger circuit, starting to count the state of the trigger circuit when the first sampling result is 0 state, and performing 1 state or 0 state accumulation counting according to the sampling result; 2) When the number of samples reaches n _samp And then judging the counting results of the 1 state and the 0 state: if the 1 state count exceeds n _samp And/2, judging that the code value is 1 code; if the 0 state count exceeds n _samp The code value is judged to be 0 code; 3) Monitoring the code value state of the trigger circuit, and when the code value is 1 code → 0 code, judging that the falling edge is true and outputting gyro data; judging that the falling edge is finished until the code value is from 0 code → 1 code; 4) And repeating the steps and judging the next falling edge. The method can solve the problems of misjudgment and missing judgment of the falling edge of the triggering square wave of the traditional triggering type optical fiber gyroscope, improve the judgment accuracy of the falling edge of the square wave, ensure that the data output stability of the optical fiber gyroscope is better, and further improve the precision of the optical fiber gyroscope.

Description

Method for judging falling edge of triggering square wave of fiber-optic gyroscope

Technical Field

The invention relates to the technical field of fiber optic gyroscopes, in particular to a method for judging falling edges of trigger square waves of a fiber optic gyroscope.

Background

Fiber optic gyroscopes have found wide application in inertial navigation systems due to their inherent advantages. The inertial navigation system generally adopts three gyroscopes and three accelerometers to sense information such as triaxial angular velocity, linear acceleration and the like, and then carries out navigation calculation according to the information. In order to ensure that the angular velocity information provided by the three gyros is provided at the same time, namely synchronously, the system generally adopts the method that signals (trigger signals) are sent to the gyros at the same time, and the gyros feed back the angular velocity data after receiving the trigger signals.

In the optical fiber gyroscope, a system usually adopts a square wave falling edge as a trigger signal, the square wave falling edge trigger means that the system sends a square wave signal with a certain frequency (predetermined), and the gyroscope responds to one frame of data after identifying the square wave falling edge. The trigger type optical fiber gyroscope can work only by adding a trigger signal judgment part, and the judgment of the trigger signal is very important for the trigger type optical fiber gyroscope. If the determination method is too strict, a false determination may be caused (the true trigger signal is determined to be false); on the contrary, if the determination method is too loose, erroneous determination may be caused (false trigger signal is determined to be true). Therefore, the output instability of the optical fiber gyroscope data is easily caused by the missing judgment or the error judgment caused by the improper judgment method, so that errors are generated, and the gyroscope precision is reduced.

At present, the judgment method of the square wave falling edge mainly comprises a single-point judgment method and a pulse judgment method: 1) Referring to fig. 1, the single-point determination method is to determine the state on the trigger line at intervals of the driving clock signal period, and when the state on the trigger line changes from 1 to 0, the falling edge is considered to be true. 2) Referring to fig. 2, in the pulse determination method, the driving clock signal period is used as an interval to determine the level state on the trigger line, when the state on the trigger line changes from 1 to 0, the state is shifted to a 0 state timing state, and if the duration time of the 0 state reaches a set threshold, the trigger falling edge is considered to be true; in the 0 state timing process, the trigger signal is also monitored, and if the 1 state occurs (namely, the 0 state duration is not enough), the interference is considered and no response is given.

Both the above two determination methods can accurately determine an ideal trigger circuit, but for an actual touch circuit, due to the influence of electromagnetic interference or a complex temperature environment, various interferences exist in the trigger signal on the trigger circuit, so that the waveform is distorted, as shown in fig. 3. For convenience of description, the interference of type a is referred to as negative interference and the interference of type b is referred to as positive interference in fig. 3. In the two judgment methods, certain misjudgment or missed judgment probability exists under the condition that negative interference and positive interference exist.

Therefore, how to improve the accuracy of determining the falling edge of the square wave, reduce the error of triggering the fiber-optic gyroscope caused by misjudging or missing judging of the trigger signal, and improve the precision level of triggering the fiber-optic gyroscope has become a technical problem that needs to be solved by those skilled in the art urgently.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a method for judging the falling edge of the triggering square wave of the fiber-optic gyroscope, which can solve the problems of misjudgment and missing judgment of the falling edge of the triggering square wave of the traditional triggering fiber-optic gyroscope, improve the judgment accuracy of the falling edge of the square wave, ensure that the data output stability of the fiber-optic gyroscope is better and further improve the precision of the fiber-optic gyroscope.

In order to solve the technical problem, the technical scheme adopted by the invention is as follows: a method for judging the falling edge of a fiber-optic gyroscope trigger square wave is characterized by comprising the following steps: the method comprises the following steps:

1) Sampling the state of the trigger circuit according to the frequency of a sampling clock, and if the sampling result is a high level, the state is counted as 1 state, and the sampling result is a low level, the state is counted as 0 state; when the first sampling result is 0 state, starting to count the state of the trigger line, and performing 1 state or 0 state accumulation counting according to the sampling result in the sampling period;

wherein, the number of samples in each sampling period is:

in the formula: n is _samp -number of sampling points; f. of _samp -sampling the clock frequency; bps-baud rate;

2) When the number of samples reaches n _samp And then judging the counting results of the 1 state and the 0 state: if the 1 state count exceeds n _samp And/2, judging that the code value is 1 code; if the 0 state count exceeds n _samp If the code value is 0 code, judging that the code value is 0 code;

3) Monitoring the code value state of the trigger circuit, and when the code value is 1 code → 0 code, judging that the falling edge is true and outputting gyro data; judging that the falling edge is finished until the code value is from 0 code → 1 code;

4) And repeating the steps and judging the next falling edge.

Further, the duration of the code value is 5-10 mus.

Compared with the prior art, the invention has the following advantages: the accuracy of square wave falling edge judgment is improved by judging the virtual code value, namely the '0' code, of the square wave falling edge, and the performance of the square wave falling edge triggered fiber optic gyroscope is favorably improved; the data output stability of the fiber-optic gyroscope is better, and the precision of the fiber-optic gyroscope is improved.

Drawings

Fig. 1 is a block diagram of a single point decision method in the prior art.

Fig. 2 is a block diagram of a pulse determination method in the prior art.

Fig. 3 is a schematic diagram of a trigger signal waveform in the presence of interference.

FIG. 4 is a schematic diagram illustrating the principle of determining the code value of the falling edge of the square wave according to the present invention.

FIG. 5 is a block diagram of a code value determination method according to the present invention.

Detailed Description

The invention will be further explained with reference to the drawings and the embodiments.

Example (b): referring to fig. 4 and 5, a method for determining a falling edge of a fiber optic gyroscope trigger square wave includes the following steps:

in digital communication, a certain time, namely single code duration, is kept in single code value transmission; the inverse of the duration of a single code is the baud rate. In the scheme, the code value state judgment (judging whether the code is 1 code or 0 code) is carried out by a maximum likelihood estimation method, and the specific process is as follows:

1) Sampling the state of the trigger circuit according to the frequency of the sampling clock, judging the state of the trigger circuit, and counting as a digital 1 state if the sampling result is a high level and counting as a digital 0 state if the sampling result is a low level; and starting to count the state of the trigger line when the first sampling result is in the 0 state, and performing 1-state or 0-state accumulation counting according to the sampling result in the sampling period.

Wherein, the number of samples in each sampling period is:

in the formula: n is _samp -number of sampling points; f. of _samp -sampling the clock frequency; bps-baud rate.

2) When the number of samples reaches n _samp And then judging the counting results of the 1 state and the 0 state (namely judging the 0 code): if the 1 state count exceeds n _samp And/2, judging that the code value is 1 code; if the 0 state count exceeds n _samp And/2, judging that the code value is 0 code.

The code value state judgment is carried out by a maximum likelihood estimation method, the misjudgment problem caused by communication line interference can be effectively solved, and the real condition of the code value of the communication line can be more accurately reflected. When the code is set too short (i.e., when the virtual code is set, the duration of a single code is referred to), the influence that positive interference and negative interference cannot be effectively proposed may be caused, and conversely, when the code is set too long, the response time of the gyroscope may be too long, and the bandwidth of the gyroscope may be influenced. Therefore, the minimum value capable of effectively eliminating interference is selected during the (virtual) code, and the time length of the optimal code value is 5-10 mus.

3) According to digital communication, a square wave signal can be seen as several consecutive 1 codes and consecutive 0 codes alternately appearing at a certain frequency. Therefore, the falling edge trigger of the square wave can be equivalently regarded as 0 code trigger, i.e. a virtual 0 code is equivalently generated after the falling edge. Therefore, in the judging process, the code value state of the trigger circuit is monitored, when the code value is 1 code → 0 code, the falling edge is judged to be true, and gyro data are output; and then 1 code judgment is carried out, and when the code value is from 0 code → 1 code, the end of the falling edge is judged.

4) And repeating the steps and judging the next falling edge.

As a specific embodiment, the square wave falling edge determination process according to the present invention is as follows:

BEGIN：

trigger signal monitoring state:

if the trigger signal is in 1 state:

keeping in a trigger signal monitoring state;

otherwise:

skipping to a trigger signal sampling state;

trigger signal sampling state:

if the sampling number does not reach the specified value:

if the trigger signal is in 1 state:

1-state counting and accumulating 1 of the trigger signal;

otherwise:

the trigger signal 0 state counts and accumulates 1;

otherwise:

jumping to a trigger signal judgment state;

judging state of the trigger signal:

if the count of the trigger signal in the 1 state is greater than the count of the 0 state:

judging whether the trigger signal is false;

jumping to a trigger signal monitoring state;

otherwise:

the trigger signal judgment result is true;

skipping to a judgment result output state;

judging the output state of the result:

giving a judgment result of true;

jumping to the next judgment state;

the next determination state:

if the trigger signal is 1 code:

jumping to a trigger signal monitoring state;

otherwise:

keeping the next determination state;

END。

it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting the technical solutions, and those skilled in the art should understand that the technical solutions of the present invention can be modified or substituted with equivalent solutions without departing from the spirit and scope of the technical solutions, and all should be covered in the claims of the present invention.

Claims

1. A method for judging the falling edge of a fiber-optic gyroscope trigger square wave is characterized by comprising the following steps: the method comprises the following steps:

1) Sampling the state of the trigger circuit according to the frequency of a sampling clock, and if the sampling result is a high level, the state is counted as 1 state, and the sampling result is a low level, the state is counted as 0 state; starting to count the state of the trigger line when the first sampling result is in a 0 state, and performing 1-state or 0-state accumulation counting according to the sampling result in a sampling period;

wherein, the number of samples in each sampling period is:

in the formula: n is a radical of an alkyl radical _samp -number of sampling points;f _samp -sampling the clock frequency; bps-baud rate;

2) When the number of samples reaches n _samp And then judging the counting results of the 1 state and the 0 state: if the 1 state count exceeds n _samp The code value is judged to be 1 code; if the 0 state count exceeds n _samp If the code value is 0 code, judging that the code value is 0 code;

4) And repeating the steps and judging the next falling edge.

2. The method for determining the falling edge of the fiber-optic gyroscope trigger square wave according to claim 1, wherein the method comprises the following steps: the duration of the code value is 5-10 mus.