CN201133818Y - North seeking device - Google Patents

Abstract

The utility model relates to a north-finding device used in the field of orientation and location, in particular to an inertial north-finding device using accelerometers as inertial components, which is composed of a servosystem, a motor-driven rotary platform, an encoder, a measuring accelerometer, an additional accelerometer and a data acquiring and processing system; wherein, the encoder is arranged on a motor; the measuring accelerometer and the additional accelerometer are fixed on the rotary platform; the data acquiring and processing system can be connected with a serial port; the measuring axis (a<k1>) of the measuring accelerometer arranged on the edge of the rotary platform is vertical to the surface of the rotary platform; the measuring axis (a<k2>) of the additional accelerometer arranged at the center of the rotary platform is pointed to the measuring accelerometer along the radius vector of the rotary platform. The north-finding device of the utility model has a function of automatic levelling compensation. The levelling compensation includes the compensation of measuring errors caused by levelling errors and the elimination of interference noise generated by levelling errors. Consequently, the north-finding device of the utility model effectively increases measuring precision.

Description

North finding device

Technical field

The utility model relates to a kind of north finding device that is applied to orientation, positioning field, and is particularly a kind of with the inertia north finding device of accelerometer as inertia device.

Background technology

Inertia is sought the important component part that northern technology is the inertial technology field.It obtains north orientation information by measurement or responsive earth rate, thereby measures the true meridian position of any measuring point, realizes looking for northern process.Along with the development of accurate measuring technique, seek north location and all multi-methods also occurred as multiple high precision north finding methods such as inertia method, the method for observation, geodesic method, satnav method, object of reference methods.But in the tunnel, wait under the specific conditions such as complex-terrain and complicated weather environment under water, the method for observation, geodesic method, satnav method and object of reference method all can be subjected to conditionality in various degree, and perhaps precision is low, perhaps can't implement at all.Have only the inertia method could not be subjected to the interference of natural conditions or environment, independently finish and seek northern task, and have characteristics such as stream time length, precision height.Therefore, the using value that the research of inertia north finding method is had its uniqueness.

North finding device has obtained using widely in a lot of fields, except having the very important application, also more and more demonstrate wide application prospect in as civil engineering fields such as tunnel construction, mining, geodetic surveying, resource explorations at other at aspects such as Aeronautics and Astronautics, marine navigation and weapon guidances.Present north finding device mainly adopts air supporting rate gyro, dynamic tuned gyroscope, ring laser gyro, optical fibre gyro and electrostatic gyroscope etc. to finish detection to earth rate as inertia device, and cost is very high.Along with the further raising of accelerometer manufacturing accuracy, non-gyroscopic inertia measuring unit has appearred the eighties in 20th century, because it has abandoned expensive gyro, thereby manufacturing cost is greatly descended.Therefore, the research of carrying out non-gyroscope north searching device all has important meaning at military, civil area.

But, because non-gyroscope north searching system is based on Coriolis acceleration principle, by the turntable dynamic modulation, the compound generation De Geshi of tangential velocity acceleration is output as a sinusoidal signal on the north component of rotational-angular velocity of the earth and this aspect, by the pairing phase place of the peak value that detects this sinusoidal signal, be the direct north of position on the earth.In the measuring process when turntable axes of rotation skew certain angle because the influence of earth rate vertical component, system looks to no longer be the direction of earth rotation north component, but north component and vertical component synthesis rate direction.At present, the someone proposes at the turntable edge of measuring the accelerometer symmetry coriolis acceleration meter to be installed, and coriolis acceleration meter measurement axis is parallel to the turntable face, along the turntable tangential direction.When measuring turntable axes of rotation skew certain angle by the coriolis acceleration instrumentation, the influence of earth rate vertical component.

But, learn that because the inclination of turntable, there is the acceleration of one-period variation in the turntable marginal point in vertical, causes serious disturbance to extracting the De Geshi acceleration signal through theoretical analysis.Therefore, the size of leveling error can have a strong impact on the measuring accuracy of system, even the function realization, must disturb this part of system and carry out filtering.

Summary of the invention

The purpose of this utility model be for eliminate leveling error to the influence of measuring accuracy, filtering leveling error to the interference that system produces, a kind of north finding device that improves structure is proposed.

The utility model north finding device, by by servo-drive system, motor-driven turntable, be arranged on scrambler on the motor, be installed with measurement accelerometer and coriolis acceleration meter on turntable, reaching the data Collection ﹠ Processing System that connects by serial ports forms, be characterized in that described measurement accelerometer is arranged on the edge of described turntable, its measurement axis a _K1Perpendicular to table top, described coriolis acceleration meter is arranged on the center of turntable, its measurement axis a _K2Point to the measurement accelerometer along the turntable radius vector.

The utility model north finding device has automatic leveling compensate function.Said leveling compensation comprises the Compensation of Measuring Error that leveling error is caused, the elimination of the interference noise that leveling error is caused.Therefore effectively raise measuring accuracy.

Description of drawings

Fig. 1 is the structural representation of the utility model north finding device;

Fig. 2 is the analysis synoptic diagram of leveling error to the precision influence;

The interference analysis synoptic diagram that Fig. 3 produces for leveling error;

Fig. 4 is the course of work synoptic diagram of the utility model north finding device.

Embodiment

The embodiment that provides below in conjunction with accompanying drawing is described in further detail the utility model.

With reference to Fig. 1, by by servo-drive system, motor-driven turntable 3, be arranged on scrambler on the motor, be installed with measurement accelerometer 1 and coriolis acceleration meter 2 on turntable 3, reaching the data Collection ﹠ Processing System that connects by serial ports forms, it is characterized in that, described measurement accelerometer 1 is arranged on the edge of described turntable 3, apart from turntable 3 distances of shaft centers from being R, its measurement axis a _K1Perpendicular to table top, described coriolis acceleration meter 2 is arranged on the o place, center of turntable 3, its measurement axis a _K2Point to measurement accelerometer 1 along turntable 3 radius vectors.

The principle of work of the utility model north finding device:

As shown in Figure 2, when turntable inclination ε is a low-angle, at this moment azimuthal error is:

---angle of latitude

In medium latitude area

With ε be the same order of magnitude, so must carry out leveling compensation.Coriolis acceleration meter 2 output signals that are installed on the turntable are modulated to through turntable:

a′＝a ₀′+gsinεsin(Ωt-ζ)+σ _g′

In the formula: a ₀' being the No. of believing one side only zero of accelerometer, ε is the turntable pitch angle, σ _g' be the accelerometer noise in output signal, ζ is the position angle compensation rate that the pitch angle causes.

O is the turntable center among the figure, and O ' is for surveying pitch angle accelerometer mounting center, and A, B represent the projection of Corioli's acceleration on R and orthogonal directions thereof when initial, and after AC amplifier filtering, its output model can be rewritten as:

a _g＝gsinεsin(Ωt-ζ)+σ _g′＝CsinΩt-DcosΩt+σ _g′

C=gsin ε cos ζ in the formula, D=gsin ε sin ζ

Can try to achieve C, D through synchronous detection, handle the valuation that can get ε and ζ through least square

$\mathrm{\&epsiv;}={\sin }^{-1}\frac{\sqrt{C^2+D^2}}{g}$

$\mathrm{\&zeta;}={\mathrm{tg}}^{-1}\frac{D}{C}$

As shown in Figure 3, OCDE is a surface level among the figure, and OABE is the turntable face, measure accelerometer 1 and be installed in the A point, and β when accelerometer 1 forwards the B point to=Ω t+ λ, then

S＝BD＝EBsinα＝Rsinβsinε

That is: S=Rsin ε sin (Ω t+ λ)

Then the acceleration that is caused by leveling error of A point measurement accelerometer 1 sensitivity can approximate representation be:

a _z＝S″＝-RΩ ²sinεsin(Ωt+λ)

Coriolis acceleration meter 2 through turntable 3 modulated output signals is:

a _o＝rΩ ²+gsinεsin(Ωt+λ)

Wherein r is the eccentric arm apart from turntable shaft, r Ω ²Be normal value, can pass through the AC amplifier filtering, its output model can be rewritten as:

a _o＝g?sinεsin(Ωt+λ)

As seen, $a_z=-\frac{{\mathrm{R\&Omega;}}^2}{g}{a}_o,$ Irrelevant with pitch angle ε.

By vector calculus, can eliminate the interference that causes by leveling error of measuring accelerometer 1 sensitivity.

As seen, realized eliminating the noise that leveling error causes, the measuring error that leveling error causes has been revised by along the radius vector direction coriolis acceleration meter 2 being installed at turntable 3 centers.

With reference to Fig. 4, in the course of work, by the servo-drive system drive motor, driven by motor scrambler and accelerometer 1, accelerometer 2 are around the axle center uniform rotation, the signal that accelerometer 1 and accelerometer 2 are measured obtains after through the ratio subtraction is the Corioli's acceleration signal, in conjunction with the output valve of scrambler, calculate the scrambler zero-bit of unmodified and the angle of north orientation.The signal of accelerometer 2 output calculates the measurement error value that leveling error causes through after the individual processing, brings this error amount into scrambler zero-bit that previous calculations goes out and the angle of north orientation, is exactly the final measurement of this north-seeking system.

Claims (1)

1. north finding device, by by servo-drive system, motor-driven turntable (3), be arranged on scrambler on the motor, be installed with measurement accelerometer (1) and coriolis acceleration meter (2) on turntable (3), reaching the data Collection ﹠ Processing System that connects by serial ports forms, it is characterized in that, described measurement accelerometer (1) is arranged on the edge of described turntable (3), its measurement axis a _K1Perpendicular to table top, described coriolis acceleration meter (2) is arranged on the center of turntable (3), its measurement axis a _K2Point to measurement accelerometer (1) along turntable (3) radius vector.

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