CN1224825C - Optical fiber sensor coil and method of counteracting temperature error automatically - Google Patents

Abstract

An optical fiber sensor coil and a method for automatically offsetting temperature errors belong to the field of optical fiber sensing. The symmetrical midpoint of the optical path of the coil is located in the innermost layer of the coil, and the arrangement order of the optical fibers on both sides of the midpoint of the optical path is repeated alternately from the first layer to the i-1th layer, starting from the i-th layer from the inside to the outside, The arrangement order changes, but the arrangement order of the next unit optical fiber is still arranged in an alternately repeated order until the last layer of optical fiber, and the position of i is determined according to the following method. The method is: according to the parameters of the coil, determine the position coordinates of each layer of the coil in the optical path; based on the finite difference method, obtain the temperature change of each layer of the coil along the radial direction; The polarity and magnitude of the contribution of the total error of the coil; then adjust the arrangement order of the optical fibers in each layer of the coil until the total temperature error is minimized. The invention can significantly reduce the influence of temperature effect on the output of the fiber optic gyroscope.

Description

The fiber optic sensor coil of counteracting temperature error automatically and method

Technical field: what the present invention relates to is the fiber optic sensor coil and the method for the cell winding of a kind of optical fibre gyro, particularly a kind of counteracting temperature error automatically, belongs to sensory field of optic fibre.

Background technology: interferometric fiber optic gyroscope is to be made of LASER Light Source, beam splitter, Polarization Control device, the cell winding of gyro, photoelectric detector.Wherein, the light beam that light source sends is divided into two-beam by beam splitter, respectively along the cell winding by gyro clockwise and counterclockwise, when the cell winding of gyro was static, the light path that is experienced during the cell winding of the reciprocal light in this two bundles direction of propagation by gyro was identical; When the cell winding of gyro rotates with measurand, the light path difference that is experienced during the cell winding of this two-beam by gyro, the phase change that is experienced is also different.According to the Sagnac effect, the phase differential direct ratio of two-beam experience and the rotating speed of measurand so just can be measured phase differential by photoelectric detector and signal Processing and record rotating speed.The precision of interferometric fiber optic gyroscope is subjected to many factors, especially the restriction of environmental factor.Wherein most importantly because the influence of the hot nonreciprocal effect that temperature variation causes.When variation of ambient temperature, the cell winding inside temperature everywhere of gyro is changing with different speed thereupon.The parameters such as refractive index of each several part are also corresponding in the cell winding of gyro is changing.So when reciprocal light in different moment during by same section optical fiber in the cell winding of gyro, the light path difference that is experienced, phase change is also different.Like this, even measurand is not rotated,, also there is phase differential between the reciprocal light owing to variation of temperature.The phase differential that consequent phase differential and rotating speed cause can't be differentiated, and has therefore introduced error, has seriously limited the precision of interferometric fiber optic gyroscope.R.B.Dyott is at Electronics Letters (electronics wall bulletin) 7th November1996, Vol.32, and No.23, P2177 writes articles Reduction of the Shupe effect in fiberoptic gyros; The random-wound coil. (reduce the temperature effect in the optical fibre gyro: coiling) at random, the loop construction that twines has at random been proposed in this article, by making in the coil with respect to the relative position of the optical fiber on point-symmetric 2 points in the light path (hereinafter to be referred as symmetrical 2 points) stochastic distribution vertically and radially, thus make reciprocal light when 2 of symmetries by coil because the phase differential randomization that temperature effect is introduced makes that corresponding hot nonreciprocal phase shift summation reduces.But these technology are not discussed quantitatively and are solved and how to make full use of mode and the characteristics that temperature effect works reduce total output error in each layer of coil, and this loop construction manufacturing process that method proposed that reduces temperature effect is comparatively complicated, and has introduced bigger noise inevitably.

Summary of the invention: purpose of the present invention is at the deficiencies in the prior art and defective, a kind of fiber optic sensor coil and method of counteracting temperature error automatically are provided, can significantly reduce the influence that optical fibre gyro output is subjected to temperature effect, solve the problem that exists in the background technology.The present invention realizes by following technical scheme, if be positioned at each layer optical fiber of light path mid point one side with the A representative, the B representative is positioned at each layer optical fiber of light path mid point opposite side, then the symmetrical mid point of coil light path is positioned at the coil innermost layer, the optical fiber that is positioned at light path mid point both sides putting in order from inside to outside, (i is an odd number to the i-1 layer by the 1st layer, i is greater than 1) can be expressed as ABBAABBA ... ABBA, promptly from innermost layer, with two-layer be a unit, previous element earlier around the A optical fiber again around the B optical fiber, a then back unit earlier around the B optical fiber again around the A optical fiber, so alternately repeat.The i layer rises from inside to outside, putting in order changes, and promptly unit beginning of i layer is identical with the coiling order of previous element optical fiber, if the previous element optical fiber arrangements is AB in proper order, then a unit optical fiber that is begun by the i layer puts in order and still is AB, and vice versa; And the putting in order of next unit optical fiber still according to alternately repeated series arrangement, be AB if a unit optical fiber that is begun by the i layer puts in order, putting in order of then next unit optical fiber is BA, and vice versa, so alternately repeat, until last one deck optical fiber.The position of i determines that according to following method according to the effect that above-mentioned mutual alignment relation is arranged, optical fiber gyro coil of the present invention is than traditional optical fiber gyro coil, and under identical temperature variation, the error of being introduced has reduced about 60%.

The invention provides the method for the error that hot nonreciprocal effect causes that temperature causes in a kind of cell winding accurately definite and obviously minimizing optical fibre gyro, concrete grammar is as follows:

(1), determines the inside and outside footpath of the cell winding of gyro, the coiling number of plies, every layer of number of turns, coil initial configuration, according to the inside and outside footpath of coil, the parameter of the coiling number of plies, every layer of number of turns, coil initial configuration is determined the position coordinates of each layer of cell winding in light path of gyro;

(2), based on method of finite difference, when obtaining ambient temperature and changing, the cell winding of gyro is the temperature variations of each layer radially;

(3), according to each layer of the cell winding position coordinates and the temperature variations of known gyro, and determine polarity and the size of each layer optical fiber to the contribution amount of the temperature error of the cell winding of gyro through normalized;

(4), according to each layer of cell winding of gyro polarity and size to the contribution amount of error, be arranged in mutual the putting in order of each layer optical fiber on the light path ad-hoc location in the cell winding of adjustment gyro, thereby change the polarity and the size of each layer of cell winding error contribution amount of gyro, make nonreciprocal phase shift error that temperature effect is introduced in some zone of coil, can be with temperature effect be close in other regional nonreciprocal phase shift error amplitudes of introducing of coil, polarity is opposite, therefore cancel out each other, thereby reduce total output error.Until the total temperature error minimum of the cell winding of gyro.

This method has been considered in the cell winding of gyro each layer line circle length with the variation of its radial position, and the nonlinear temperature of the cell winding inside of gyro distributes, and simultaneously, the discrete form that this method had is convenient to analyze on computers.

The present invention has substantive distinguishing features and marked improvement, the present invention is according to the temperature effect requirement of cancelling out each other, determine the pickup wire coil structures according to quantitative analysis results, can significantly reduce the influence that optical fibre gyro output is subjected to temperature effect, when utilizing the present invention to reduce the temperature effect error, people needn't rule of thumb adjust the structure of each cell winding more one by one, thereby obviously reduce required adjustment time and workload.

Description of drawings: Fig. 1 structural representation of the present invention

Embodiment: as shown in Figure 1, in the optical fiber gyro coil of the present invention, the 1st layer to the i-1 layer from inside to outside, wherein i is an odd number, i is greater than 1, the optical fiber that is positioned at light path symmetry mid point both sides is by alternately repeating, it is the series arrangement of ABBA, from the i layer, putting in order changes, and promptly unit beginning of i layer is identical with the coiling order of previous element optical fiber, if the previous element optical fiber arrangements is AB in proper order, then a unit optical fiber that is begun by the i layer puts in order still and to be AB, and vice versa, and the putting in order still according to alternately repeated series arrangement of next unit optical fiber, if putting in order, a unit optical fiber that is begun by the i layer is AB, putting in order of then next unit optical fiber is BA, and vice versa, so alternately repeats, until last one deck optical fiber, the position of i is determined according to following method.

Describing one below in conjunction with the method for counteracting temperature error automatically originally was the concrete of quadrapole structure coil

Embodiment:

(1) known its internal diameter is that 40 millimeters, external diameter are 50 millimeters, and the optical fiber total length of institute's coiling is 224 meters, has 24 layers, 1584 circles.Can calculate the position coordinates of each layer optical fiber in the pairing light path of coil by above-mentioned parameter.

(2), can utilize method of finite difference to calculate the situation of change of the temperature of each layer radially with environment temperature according to the loop construction parameter.

(3) according to known each layer of coil position coordinates and temperature variations, and the process normalized is determined polarity and the size of each layer optical fiber to the contribution amount of the temperature error of the cell winding of gyro;

(4) according to each layer of cell winding of gyro polarity and size to the contribution amount of error, be arranged in mutual the putting in order of each layer optical fiber on the light path ad-hoc location in the cell winding of adjustment gyro, the 1st layer to the 16th layer from inside to outside, the optical fiber that is positioned at light path symmetry mid point both sides is by alternately repeating, being the series arrangement of ABBA, the 17th layer changes and puts in order from inside to outside, if the previous element optical fiber arrangements is AB in proper order, then being put in order by a unit optical fiber of the 17th layer of beginning still is AB, and vice versa; And the putting in order of next unit optical fiber still according to alternately repeated series arrangement, thereby change the polarity and the size of each layer of cell winding error contribution amount of gyro, make the phase error of temperature effect in preceding 16 layers of introducing of coil, can the phase error amplitude of 8 layers of introducing be close behind coil, polarity is opposite with temperature effect, therefore cancel out each other, thereby make total output error reduce about 60% than the coil of quadrapole structure.

Claims (3)

1. An optical fiber sensor coil that automatically offsets temperature errors, is characterized in that if A represents each layer of optical fiber located on one side of the midpoint of the optical path, and B represents each layer of optical fiber located on the other side of the optical path midpoint, then the symmetry of the coil optical path The midpoint is located in the innermost layer of the coil, and the optical fibers located on both sides of the midpoint of the optical path are arranged from inside to outside, from the first layer to the i-1th layer, i is an odd number, and i is greater than 1, which can be expressed as ABBAABBA...ABBA, Repeating this alternately, starting from the i-th layer from the inside to the outside, the arrangement order changes, while the arrangement order of the next unit optical fiber is still arranged in the order of alternating repetition, and so on until the last layer of optical fiber. 2. The optical fiber sensor coil for automatically offsetting temperature errors according to claim 1, further characterized in that starting from the innermost layer, two layers are used as a unit, and the former unit first winds the A-side optical fiber and then the B-side optical fiber , then the latter unit first winds the B-side fiber and then the A-side fiber. The winding sequence of a unit starting from the i-th layer is the same as that of the previous unit. The arrangement order of a unit fiber is still AB, and vice versa, if the arrangement order of a unit fiber starting from the i-th layer is AB, then the arrangement order of the next unit fiber is BA, and vice versa, and this is repeated alternately until the end A layer of fiber optics. 3. A method for automatically offsetting temperature errors, characterized in that the specific method is as follows: (1) Determine the inner and outer diameters of the sensor coil of the gyroscope, the number of winding layers, the number of turns per layer, and the initial structure of the coil. According to the inner and outer diameters of the coil, the number of winding layers, the number of turns per layer, and the initial structure of the coil Parameters to determine the position coordinates of each layer of the sensor coil of the gyroscope in the optical path; (2), based on the finite difference method, when the external environment temperature changes, the temperature changes of the sensor coil of the gyroscope along the radial layers; (3), according to the position coordinates of each layer of the sensor coil of the known gyroscope and the temperature change situation, and determine the polarity and the size of the contribution of each layer of optical fiber to the temperature error of the sensor coil of the gyroscope through normalization processing; (4), according to the polarity and size of the contribution of each layer of the sensor coil of the gyroscope to the error, adjust the arrangement order of the optical fibers of each layer located at a specific position in the optical path in the sensor coil of the gyroscope, until the total sensor coil of the gyroscope The temperature error is the smallest.