CN100529662C - Single axis fiber gyro north seeker - Google Patents

Abstract

The invention discloses a single-axle fiber gyroscope north-searching instrument which comprises a single-axle fiber gyroscope as sensing component, a rotary axle, a direction pointing line, a stepper motor, a monolithic computer and a north-searching computer. Wherein the fiber gyroscope and the direction point line are fixed on the rotary axle, the stepper motor can drive the rotary rotating for obtaining the output signals sent by the fiber gyroscope from different sites; the monolithic computer mainly control the rotating of the rotary axle, the north-searching computer perform data collection and employs its internal mathematics model to process the sampling signal and get the north-searching results. The invention also can calculate out the angle that the invention and target connecting line relative to the north direction.

Description

Single axis fiber gyro north seeker

Technical field

The invention belongs to the inertial technology field, relate generally to a kind of gyroscope north searching device, relate in particular to a kind of north finding device that adopts optical fibre gyro as sensitive element.

Background technology

Chinese patent application CN90103687.0 discloses the invention of China No. 15 Inst. No. 1 Design Inst., Ministry of Aeronautic and Astranantic Industry a kind ofly seeks northern instrument.This is sought northern instrument and adopts a flexible gyroscope being installed on the turntable and an accelerometer as detecting components and parts, detect rotational-angular velocity of the earth at a plurality of locational components by flexible gyroscope, in conjunction with the accelerometer output quantity of same position, calculate the angle of initial position and north orientation.Adopt the step motor drive turntable to rotate, realize the sampling of many measuring positions.In the driving of stepper motor, adopt the drive control module of analog circuit board as stepper motor, adopt optical pulse generator and position memory device record to be used, with zero-bit and other turned positions of determining single axle table.And when seeking north, this is sought northern instrument and all will carry out zero-bit and adjust the operation of promptly making zero automatically at every turn.In addition, this zero-bit index line of seeking northern instrument is positioned on the housing, therefore, mostly is used for the north of seeking of carrier self, seldom is used for target is sought north.

Optical fibre gyro is a kind of solid-state gyro.Because characteristics such as it has that cost is low, start-up time is short, volume is little, in light weight, low in energy consumption and strong shock resistance, has very remarkable advantages than mechanical gyro and liquid gyro, therefore, the northern instrument of seeking that has at present uses optical fibre gyro as Sensitive Apparatus, replaced mechanical gyro and liquid gyro in the past, smaller volume, the weight of seeking northern instrument lighten, power consumption reduces, cost reduces thereby make.Single fiber gyro north seeker of a kind of single shaft introduced in " compensation of optical fiber north-seaking gyro tool base motion " literary composition that Chinese periodical " inertial navigation and instrument " the 1998.No.2 phase delivers, and this article has only provided to be sought north and resolve mathematical model and do not provide the complete skill scheme of seeking northern instrument.Resolve in the mathematical model in the given north of seeking, orientation angles is resolved the gyro sampled value that has only adopted three positions and is carried out the last north of seeking and resolve, and to seek north work be not omnibearing, can only carry out in-90 °～90 ° angular range.

Summary of the invention

The technical problem to be solved in the present invention is, providing a kind of adopts single single axis fiber gyro as the northern instrument of seeking of sensitive element, this seeks northern instrument not only can carry out the comprehensive north of seeking, and it is sought northern mathematics and resolves optical fibre gyro output data that model adopts the four measuring position and seek north and resolve.

For solving the problems of the technologies described above, the present invention includes single axis fiber gyro, turntable, pedestal, housing, three angle spirals, single-chip microcomputer, seek north and resolve computing machine, display, stepper motor, driver module, conducting slip ring, two surveyor's staffs, described turntable contains rotating shaft, the rotating disk that has the direction index line, support, support and rotating disk all are connected in the rotating shaft and the rotating disk level is positioned at the top of rotating shaft, the rotating shaft two ends respectively by Bearing Installation on the upper surface of housing and pedestal and vertical with housing upper surface and pedestal end face, described single axis fiber gyro level is rack-mount, and its responsive axis is identical with direction index line on rotating shaft quadrature and direction and the rotating disk; Three uniform pedestal belows that are connected in of angle spiral; Described stepper motor is connected in the pedestal below and can drives rotating shaft drive support and rotates relative to pedestal; Described single-chip microcomputer, driver module, Xun Bei resolve computing machine and are installed on the pedestal; Described conducting slip ring rotating part and described rotating shaft are connected, and its fixed part and pedestal are connected; The output signal of described single axis fiber gyro is sent into by conducting slip ring and is sought north and resolve computing machine; The lower surface of described housing and pedestal upper surface are connected, and the upper surface of housing is that annular and tapping expose described direction index line, described two surveyor's staffs be separated by 90 the degree be installed on the annular end face of housing, described display is embedded in the side of housing; The function of described single-chip microcomputer is, resolve the transposition instruction that computing machine sends and send the instruction of transposition step number according to seeking north, resolve computing machine and send the interrupt request singal that puts in place to seeking north according to the stepper motor of the described driver module feedback signal that puts in place to described driver module; Described driver module receives that described single-chip microcomputer provides transfers the angle instruction to, drives that described stepper motor turns to the optical fibre gyro measuring position and to the single-chip microcomputer feedback stepper motor signal that puts in place; The described north of seeking is resolved computing machine and contained sampling module, sampled signal processing module, Xun Bei and resolve module, rotate control module, database module, position judging module, memory module: sampling module receives single axis fiber gyro and sends into database module stores in the digital signal of four measuring position output and with it; The sampled signal processing module contains Filtering Model, unruly-value rejecting model, and this module is carried out filtering and unruly-value rejecting to the sampled signal in the data library module, obtains the mean value of each position sampling signal and sends into memory module; Seek north and resolve module and contain and seek north and resolve model, its function is to call the sampled signal values of four measuring position in the memory module respectively, and the initial position that calculates the direction index line is with respect to the angle of north orientation and will resolve the result and send into described display and show; The function of rotating control module is whenever sampling module sends rotation command and receives the interrupt request that single-chip microcomputer sends to single-chip microcomputer after signals collecting is finished in a measuring position; Position judging module judges whether sampling module is finished the sampling of optical fibre gyro at the four measuring position output signal.

According to the present invention, a scale is connected on the described housing annular end face, its zero-bit is aimed at the initial position of described direction index line, the described north of seeking is resolved and is comprised also in the computing machine that one contains angle and resolves the angle of model and resolve module, its function is to call to seek northern result, calculates the direction index line and sends to relative to the angle value of north orientation and with the result in the four measuring position and rotate control module; Described rotation control module sends corresponding transposition step number instruction by described single-chip microcomputer to driver module, stepper motor is under the driving of driver module, driving described rotating shaft rotates, make described direction index line energized north to, the circular graduation that the direction index line is aimed at is the initial position of direction index line and the angle of north orientation.

The present invention adopts optical fibre gyro as Sensitive Apparatus, has overcome the not strong and bigger shortcoming of power consumption of north-seeking system impact resistance that mechanical gyro caused.Simultaneously, the present invention adopts the Single-chip Controlling stepper motor to rotate, than prior art adopt mimic channel realize rotating control to seek northern instrument simpler on circuit structure, safeguard more conveniently, reliability is higher and the circuit replaceability is higher.Because direction index line of the present invention is connected in the rotating shaft, therefore the direction index line can arbitrarily rotate in the scope of 360 degree, resolve simultaneously and seek north except setting in the computing machine and resolve the model at Xun Bei, also be provided with angle and resolve module, make the present invention both can finish the simple north of seeking and promptly find the north orientation function, can finish again and measure user and the line of target and the angle function of north orientation, promptly also can measure the user side to the angle of target link.The present invention has also increased scale and display, and seek north finish back side index line energized north to, make that like this seeking northern result has more intuitive, the user is simpler and directly perceived to the impression and the understanding of seeking northern result.

Description of drawings

Fig. 1 is that fiber gyro north seeker preferred embodiment structure of the present invention is formed synoptic diagram.

Fig. 2 is the vertical view of fiber gyro north seeker shown in Figure 1.

Fig. 3 is the north orientation angle definition synoptic diagram that fiber gyro north seeker of the present invention is sought out.

Fig. 4 is the principle of work synoptic diagram of fiber gyro north seeker of the present invention.

Fig. 5 is a workflow diagram of seeking single-chip microcomputer in the northern instrument shown in Figure 1.

Fig. 6 is the workflow diagram of seeking northern computing machine in the northern instrument of seeking shown in Figure 1.

Fig. 7 adopts fiber gyro north seeker of the present invention to seek the workflow diagram in north.

Embodiment

The present invention is described in further detail below in conjunction with accompanying drawing and preferred embodiment.

Just as shown in Figure 1 and Figure 2, the preferred embodiment of the present invention comprises single axis fiber gyro 1, rotating shaft 2, housing 3, has the scale 4 of set screw, the rotating disk 6 that has direction index line 5, two surveyor's staffs 7, single-chip microcomputer 8, Xun Bei resolve computing machine 9, connector 10, on ﹠ off switch 11, pedestal 12, stepper motor 13, trip bolt 14, conducting slip ring 15, three angle spirals 16, display 17, driver module 18.No. 05008 optical fibre gyro that optical fibre gyro 1 is adopted AGBT (J) model of weapon industry second 05 Research Institute; Seek north and resolve computing machine 9 employing PFM-5302I computing machines; Stepper motor 13 adopts the M24241S stepper motor of RORZE company, driver module 18 to adopt the RD-023MS module; Single-chip microcomputer 8 adopts the AT89C52 single-chip microcomputer of atmel corp.Rotating shaft 2 is an one with support, the two ends of rotating shaft 2 are connected with the top of housing 3 is vertical with pedestal 12 respectively by bearing, level is installed single axis fiber gyro 1 in the circular support in the middle of it, the upper surface of the lower surface of housing 3 and pedestal 12 is connected, and will guarantee during installation that the sensitive axes of single axis fiber gyro 1 and the end face of housing 3 and the end face of pedestal 12 are parallel to each other.Scale 4 is connected in the upper surface of housing 3, and rotating disk 6 is connected in the center, upper surface of rotating shaft 2, and the center pit that scale 4 is passed at direction index line 5 positions is exposed to seeks northern instrument outside, consistent with the rotational angle of rotating shaft 2 with the rotational angle that guarantees direction index line 5; Rotating disk 6 is all parallel with the sensitive axes of optical fibre gyro with scale 4, and makes direction index line 5 keep identical direction with the sensitive axes of optical fibre gyro 1, so that after seeking the north end, can read the initial position of direction index line 5 and the angle of north orientation from scale 4.Two surveyor's staffs 7,90 degree of being separated by are installed in the upper surface of housing 3, three angle spiral 16 uniform belows that are connected in pedestal 12.When using the present invention to seek north, by adjusting three angle spirals the bubble of two surveyor's staffs is mediated, the sensitive axes that so just can make optical fibre gyro 1 is on any turned position, all remain in the plane parallel with surface level, eliminate the out-of-level input that brings of sensitive axes with this and disturb, the output signal of guaranteeing optical fibre gyro 1 meets seeks the assumed condition that model is resolved in north.Stepper motor 13 is installed in pedestal 12 lower surfaces, and its transmission shaft and rotating shaft 2 are connected by trip bolt 14, is exactly the rotational angle of rotating shaft 2 with the rotational angle that guarantees stepper motor 13, also is the rotational angle of optical fibre gyro 1.Display 17 is LCD and the side that is embedded in housing 3.Conducting slip ring 15 is enclosed within the outside of rotating shaft 2, and its rotating part and rotating shaft 2 are connected, and the upper surface of fixed part and pedestal 12 is connected, and the output signal of single axis fiber gyro 1 is sent into by conducting slip ring 15 and sought north and resolve in the computing machine 9.Driver module 18, single-chip microcomputer 8, Xun Bei resolve computing machine 19 and are installed in the space of pedestal 12 and housing 3 formations.External power supply is powered to the present invention by connector 10.

According to shown in Figure 3, the north orientation angle that the preferred embodiment of the present invention is sought out is the angle of the initial position of finger direction index line 5 with respect to geographic north, promptly is rotated counterclockwise the initial position of direction index line 5 by geographic north; Rotating shaft 2 drives optical fibre gyro 1 by counterclockwise direction and rotates arrival measurement sampling location.

The working mechanism of fiber gyro north seeker of the present invention is, detect on the circumference of rotational-angular velocity of the earth in surface level 4 components by optical fibre gyro 1, calculate the initial position of seeking northern instrument direction index line 5 or rotating shaft 2 angle by these four components with respect to north orientation every 90 degree.The present invention adopt the optical fibre gyro output of four measuring position and seek accordingly north resolve model can eliminate optical fibre gyro 1 zero partially, the constant multiplier error is to seeking northern result's influence, eliminated geographic latitude simultaneously to seeking northern result's influence, promptly geographic north does not participate in seeking north calculating.

According to shown in Figure 4, resolve computing machine and finish optical fibre gyro 1 after the output of initial measurement position sampling when seeking north, send the instructions of rotating 90 degree to single-chip microcomputer 8, single-chip microcomputer 8 converts this angle value to according to following formula the rotation step number of stepper motor 13:

$h=\mathrm{int}\left(\frac{\mathrm{\βm}}{360}\right)---\left(1\right)$

In the formula: int represents round numbers; M is that stepper motor rotates required step number of a week; The rotational angle that β provides for instruction; H is that motor rotates step number.Single-chip microcomputer 8 rotates step number with this and sends to driver module 18, and driver module 18 is according to the unit pulse of the frequency transmission respective number of setting, and it is that optical fibre gyro 1 forwards second measuring position to that stepper motor 13 drives rotating shaft 2 according to pulse drive signal.After driver module 18 sends all pulse signals, to the single-chip microcomputer 8 feedback stepper motors signal that puts in place.Single-chip microcomputer 8 constantly detects the signal that puts in place that driver module 18 sends after sending pulse signal, if the signal that puts in place is effective, promptly send the interrupt request singal that puts in place to seeking northern computing machine 9.Seek north and resolve computing machine 9 and whenever finish optical fibre gyro 1 after the output of measuring position sampling, single-chip microcomputer 8, the driver module 18 aforesaid operations process that just circulates.The detailed operation flow process of single-chip microcomputer 8 is referring to Fig. 5.

According to shown in Figure 6, seek north and resolve computing machine 9 and resolve module, angle by sampling module, sampled signal processing module, Xun Bei and resolve the function that module, control module and position judging module are finished respectively that data sampling, data processing, Xun Bei resolve, the stepper motor rotational angle resolves, sent interruptions that put in place, record and the judgement measuring position, optical fibre gyro 1 place of rotational angles instruction and response single-chip microcomputer 8 to single-chip microcomputer 8.Data sampling module is sampled in the digital signal of four measuring position output to optical fibre gyro 1, and sampled signal is stored in the data database documents.The sampled signal processing module is read the one group sampled data of optical fibre gyro on each measuring position respectively from database document, and utilizes following Filtering Model that each group sampled data is carried out filtering, disturbs with the filtering gyro noise:

${\mathrm{\Ω}}_i=\frac{1}{n}\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{\widetilde{\mathrm{\Ω}}}_i\left(j\right)---\left(2\right)$

In the formula, n is the sampling number on each measuring position,

Be the signal that each sampling obtains, Ω _iBe the signal averaging of n sampling on certain measuring position, i represents the sampling location, i=1,2,3,4 among the present invention, j=1,2,3 ... n.(2) formula of utilization obtains Ω _iAfter, utilize following unruly-value rejecting model to reject wild value again:

If $|{\widetilde{\mathrm{\Ω}}}_i\left(j\right)-{\mathrm{\Ω}}_i|>3\mathrm{\δ}$

Then order ${\widetilde{\mathrm{\Ω}}}_i\left(j\right)=0,---\left(3\right)$

In the formula, δ is the drift of gyro, j=1,2,3 ..., n.(after the individual wild value of k≤n), the employing following formula is obtained the mean value of each measuring position efficiently sampling signal and is stored in the corresponding memory module to utilize following formula to reject k.

${\mathrm{\Ω}}_i=\frac{1}{n-k}\underset{j=1}{\overset{n-k}{\mathrm{\Σ}}}{\widetilde{\mathrm{\Ω}}}_i\left(j\right)---\left(4\right)$

In the formula, j=1,2,3 ..., n-k.

Seek that north resolves that module draws according to the sampled data processing module four Ω as a result ₁, Ω ₂, Ω ₃, Ω ₄, and seek northern model solution below adopting and calculate the angle of the initial position of direction index line 5 with respect to north orientation:

Work as Ω ₁-Ω ₃〉=0 o'clock:

If Ω ₄-Ω ₂〉=0, then the initial position of direction index line and north orientation angle are α _Main,

If Ω ₄-Ω ₂＜0, then the initial position of direction index line and north orientation angle are 360 °+a _Main

Work as Ω ₁-Ω ₃＜0 o'clock, the initial position of direction index line and north orientation angle were 180 °+a _MainResolve in the model Ω in the above-mentioned north of seeking ₁Be the sampled signal result of first measuring position, Ω ₂Be the sampled signal result of second measuring position, Ω ₃Be the sampled signal result of the 3rd measuring position, Ω ₄It is the sampled signal result of the 4th measuring position.

Angle is resolved module according to seeking northern result, utilizes following computation model just can calculate direction index line 5 and rotates counterclockwise how many angles again by the 4th measuring position and can aim at the north orientation of being sought out:

β′＝450-α (6)

In the formula, α is the initial position of direction index line 5 and the angle of north orientation.If β '＜360, the angle that the direction index line need rotate counterclockwise are β=β '; If β '=360, expression direction index line 5 is in the north orientation position; If β '＞360, then direction index line 5 angle that need rotate counterclockwise is β=β '-360.Angle is resolved module result of calculation is sent to the rotation control module.The rotation control module is finished to single-chip microcomputer 8 and is sent the function of rotational angles, and accepts single-chip microcomputer 8 interrupt responses.When rotating control module after single-chip microcomputer 8 sends the rotational angles instruction, begin to wait the generation of interrupt response, if do not receive interrupt response, seek north and resolve computing machine 9 and will finish the function of other functional modules according to flow process.

The location records judge module is set variable i=1 when the present invention begins to seek north; Revolution moving 90 is spent later on, and i increases by 1.Simultaneously by judging whether i determines greater than 4 whether optical fibre gyro has realized the output of four measuring position.

According to shown in Figure 7, the course of work that the employing preferred embodiment of the present invention is sought north is as follows:

1) adjusts three angle spirals 16 after the energized, make the bubble of two surveyor's staffs at housing 3 tops be in middle position.

2) rotate rotating disk 6 earlier, direction index line 5 is aimed at the mark (, just not needing to adjust the direction index line), unscrew the adjustment screw then, the zero-bit groove of scale 4 is alignd with direction index line 5, tighten the adjustment screw then if only wonder north orientation.

3) press on ﹠ off switch 11, seek north and resolve the location records judge modules setting i=1 that computing machine 9 weighs;

4) seek north and resolve computing machine and begin the output of gyro of sampling, and deposit database document in;

5) sampling time of She Dinging arrives, and rotates control module and sends to single-chip microcomputer 8 and rotate 90 orders of dragging out a miserable existence.After sending, the sampled signal processing module is utilized model (2), model (3), model (4) in succession, obtains the optical fibre gyro output Ω of first measuring position ₁, and it is stored in correspondence position in the storer.

6) the location records judge module is finished i=i+1 calculating, and finish and judge i＞4 judgements, if judged result is false, single-chip microcomputer 8 receives the order of rotating 90 degree, call model (1) and spend the transposition step number h that is converted to stepper motor, send to driver module 18 then and rotate step numbers 90;

7) after driver module received and rotates step number, according to the pulse of the frequency of setting to stepper motor 13 transmission similar numbers, drive stepping motor 13 was rotated.After sending last pulse, send the signal that rotate in place to single-chip microcomputer 8;

8) after single-chip microcomputer 8 is received the signal that rotate in place, resolve computing machine 9 and send the interrupt request singal that puts in place to seeking north;

9) seek north and resolve computing machine 9 and receive interrupt request after, seek north and resolve computing machine 9 and begin repetition 4), 5) step, obtain the Ω of second measuring position ₂, be stored in the correspondence position in the storer.According to the rotation required time of setting of 90 degree, when receiving interrupt request, step 5) is finished;

10 repeating steps 6)～9), obtain the Ω of the 3rd measuring position ₃

11 repeating steps 6)～9), obtain the Ω of four measuring position ₄

12) the location records judge module is finished i=i+1 calculating, and finishes and judge i＞4 judgements, and obviously judged result is true.

13) seek north and resolve computing machine 9 and call and seek north and resolve module, obtain the initial position of direction index line 5 and the angle α of north orientation, and send to LCD 17 and to seek northern result, LCD 17 is display result subsequently;

14) seek north and resolve computing machine 9 and call angle and resolve module, calculate direction index line 5 and forward the required rotational angle of north orientation to, send the rotational angles instruction to single-chip microcomputer 8 by the 4th measuring position.

15) single-chip microcomputer 8 receives the order of rotating the β degree, calls model (1) the β degree is converted to the transposition step number h of stepper motor, sends to driver module 18 then and rotates step numbers;

16) repeating step 7)～8), seek north and finish.

Claims (2)

1. single axis fiber gyro north seeker, comprise turntable, pedestal [12], housing [3], stepper motor [13], driver module [18], conducting slip ring [15], display [17], described stepper motor [13] drives the relative pedestal of turntable [12] rotation according to the drive signal of driver module [18], it is characterized in that: also comprise single axis fiber gyro [1], three angle spirals [16], single-chip microcomputer [8], seek north and resolve computing machine [9], two surveyor's staffs [7], described turntable contains rotating shaft [2], the rotating disk [6] that has direction index line [5], support, support and rotating disk [6] are connected in all that rotating shaft [2] is gone up and rotating disk [6] level is positioned at the top of rotating shaft [2], rotating shaft [2] two ends are gone up with pedestal [12] in the upper surface of housing [3] by Bearing Installation respectively and are vertical with housing [3] upper surface and pedestal [12] end face, described single axis fiber gyro [1] level is rack-mount, and its responsive axis is identical with direction index line [5] on rotating shaft [2] quadrature and direction and the rotating disk [6]; Uniform pedestal [12] below that is connected in of three angle spirals [16]; Described stepper motor [13] is connected in pedestal [12] below, and its transmission shaft and described rotating shaft [2] are connected; Described single-chip microcomputer [8], driver module [18], seek north and resolve computing machine [9] and be installed on the pedestal [12]; The rotating part of described conducting slip ring [15] and described rotating shaft [2] are connected, and its fixed part and pedestal [12] are connected; The output signal of described single axis fiber gyro [1] is sent into by conducting slip ring [15] and is sought north and resolve computing machine [9]; The lower surface of described housing [3] and pedestal [12] upper surface are connected, the upper surface of housing [3] is that annular and tapping expose described direction index line [5], described two surveyor's staffs [7] be separated by 90 the degree be installed on the annular end face of housing [3], described display [17] is embedded in the side of housing [3]; The function of described single-chip microcomputer [8] is, resolve the transposition instruction that computing machine [9] sends and send the instruction of transposition step number according to seeking north, resolve computing machine [9] and send the interrupt request singal that puts in place to seeking north according to the stepper motor of described driver module [18] the feedback signal that puts in place to described driver module [18]; Described driver module [18] receives the transposition step number instruction that described single-chip microcomputer [8] provides, and drives that described stepper motor [13] turns to the optical fibre gyro measuring position and to single-chip microcomputer [8] the feedback stepper motor signal that puts in place; The described north of seeking is resolved computing machine [9] and contained sampling module, sampled signal processing module, Xun Bei and resolve module, rotate control module, database module, position judging module, memory module: sampling module receives single axis fiber gyro [1] and sends into database module stores in the digital signal of four measuring position output and with it; The sampled signal processing module contains Filtering Model, unruly-value rejecting model, and this module is carried out filtering and unruly-value rejecting to the sampled signal in the data library module, obtains the mean value of each position sampling signal and sends into memory module; Seeking north resolves module and contains and seek north and resolve model, its function is to call the sampled signal values of four measuring position in the memory module respectively, calculates direction index line [5] initial position with respect to the angle of north orientation and will resolve the result and send into described display [17] and show; The function of rotating control module is whenever sampling module sends the transposition instruction and receives the interrupt request that single-chip microcomputer [8] sends to single-chip microcomputer [8] after signals collecting is finished in a measuring position; Position judging module judges whether sampling module is finished the sampling of optical fibre gyro [1] at the four measuring position output signal.

2. single axis fiber gyro north seeker according to claim 1, it is characterized in that: a scale [4] is connected on described housing [3] annular end face, its zero-bit is aimed at the initial position of described direction index line [5], the described north of seeking is resolved and is comprised also in the computing machine [9] that one contains angle and resolves the angle of model and resolve module, its function is to call to seek northern result, calculates direction index line [5] and sends to relative to the angle value of north orientation and with the result in the four measuring position and rotate control module; Described rotation control module sends corresponding transposition step number instruction by described single-chip microcomputer [8] to driver module [18], stepper motor [13] is under the driving of driver module [18], driving described rotating shaft [2] rotates, make described direction index line [5] energized north to, the scale of the scale [4] that direction index line [5] is aimed at is the angle of direction index line [5] initial position and north orientation.

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