CN105674987A - Construction method for MEMS equivalent single-shaft rotation inertial navigation - Google Patents

Abstract

The low-frequency error of the inertial device is modulated by the regular rotation of the MEMS inertial component around the rotation axis. This is an effective method to improve the accuracy of the system. However, due to many limitations such as volume, power consumption, and cost, it cannot be achieved by adding a rotating machine. Rotational modulation, so make full use of the maneuverability of the carrier, such as the maneuverability of aircraft, ships and other carriers to achieve rotational motion, and then construct an equivalent rotational single-axis rotational modulation to reduce errors. However, when the actual shot cannot keep moving with the carrier, and must be projected, at this time, the error of the system cannot be modulated during autonomous flight, and error compensation is required during autonomous movement. Estimate the error between the two to estimate the systematic error without rotational modulation. Since the rotation modulation cannot modulate the error of the rotation axis, the error caused by the rotation axis gyroscope is calculated using the similarity of the MEMS gyroscope.

Description

A construction method of MEMS equivalent single-axis rotary inertial navigation

technical field

The invention relates to the field of rotary inertial navigation, in particular to the construction method of rotary inertial navigation.

technical background

With the development of MEMS inertial technology, MEMS inertial measurement system has become the first choice for various tactical weapon guidance systems due to its advantages of low cost, small size, integration, low power consumption, high impact resistance, and mass production. The attitude accuracy of the strapdown measurement system constructed by MEMS inertial devices mainly depends on the gyroscope drift, and the accuracy is low.

The low-frequency error of the inertial device is modulated by the regular rotation of the inertial unit (MIMU) around the rotation axis. This rotation modulation technology has become one of the key technologies for improving the accuracy of inertial navigation abroad. Under the condition of not using external information, the automatic Compensating the system error caused by gyro drift, accelerometer constant value and slowly changing error can also eliminate the influence of scale coefficient error and installation error, which is an effective way to improve the accuracy of MEMS inertial measurement system.

Compensating errors through rotation modulation is different from calibration, initial alignment and calibration, which need to estimate the inertial component drift and then compensate. The rotation modulation method does not need to know the estimated value of the inertial component drift error, but modulates the error into a certain period In the form of change, in the process of navigation calculation, the integral operation is used to automatically offset the error on average.

If you want to introduce the idea of rotary inertial navigation into tactical weapons, you cannot have a navigation system like a ship, which is not limited by its size and power consumption. Because tactical weapons require its navigation system to be small in size, low in cost, and low in power consumption. Low and impact resistance, etc., if a rotating mechanism is introduced to realize rotary inertial navigation, precision motors, drive circuits and power supplies are required, which are difficult to meet the requirements of tactical guided weapons.

In order to be able to achieve rotation modulation in the guidance system of tactical weapons to improve the navigation accuracy of the system, the rotation inertial navigation cannot be realized by the self-rotation of the inertial navigation system, so the external motion is used to realize the rotation inertial navigation, which is called equivalent rotation inertial navigation.

Since tactical weapons are generally attached to other carriers, such as missiles and bombs, they must be hung or embedded on the carrier aircraft. The weapons on the ship are also installed on a certain part of the ship, and they must move with the ship before launching.

Tactical weapons generally cannot be launched directly. Before launching, they generally need to transfer the alignment, which requires high initial accuracy. Therefore, the parameters required for the alignment are provided to the inertial navigation through the equivalent rotation.

Therefore, the maneuverability of the carrier is fully utilized, such as the maneuverability of aircraft, ships and other carriers to achieve rotational motion, and then the equivalent rotational inertial navigation is constructed for error modulation to provide accurate parameters for transfer alignment during maneuvering.

Contents of the invention

For guided weapons using MEMS inertial measurement systems, the working time is extremely short and requires high alignment accuracy, especially attitude accuracy. At the same time, it can estimate and compensate inertial device errors during the alignment process to improve navigation within the effective working time. precision.

Utilizing the maneuvering of the carrier, it is generally possible to do heading maneuvers, but the pitching and rolling maneuvers will be greatly restricted. For example, it is difficult for carrier aircraft, ships and vehicles to achieve "somersault" and "rolling" movements.

Although pitch and roll maneuvers can be done to a certain extent, 180 ^° maneuvers cannot be achieved, so it is not enough to achieve rotational modulation with carrier maneuvers in these two axes.

But there are some special carriers, such as submarines, that can achieve complex maneuvers.

For carriers such as aircraft, ships, and vehicles, it is easy to achieve course maneuvering, so the carrier course maneuver is used to achieve rotational motion to modulate the device error of the inertial navigation system of the guided weapon, thereby reducing the system error, and providing a basis for the transmission of alignment and inertia. Device error estimation and compensation provide parameters.

Set missile-borne inertial navigation coordinate system , the carrier coordinate system , the inertial coordinate system , the earth coordinate system , the navigation coordinate system .

Set the inertial navigation coordinate system at the initial moment ( ) and the carrier coordinate system ( ) coincide, and then perform heading maneuvers, that is, the inertial navigation coordinate system revolves around the z-axis at an angular velocity continuous rotation, the The transformation matrix between the moment inertial navigation coordinate system and the navigation coordinate system can be expressed as: .

The difference between using motorized construction rotation and direct rotation is the inertial navigation coordinate system ( ) and the carrier coordinate system ( ) has been coincident, that is, to maintain the state of the initial moment.

The attitude angle error model of the MEMS strapdown measurement system is , the direction along the longitudinal axis of the carrier is the x-axis, the vertical direction of the carrier is the z-axis, and the carrier coordinate system is constructed according to the right-handed coordinate system, In order to calculate the attitude error between the navigation coordinate system and the real navigation coordinate system, and are the angular velocity and the angular velocity error, respectively, is the strapdown attitude matrix, Represented in the navigation coordinate system Intrasystem, Navigation Coordinate System relative inertial coordinate system The rotational angular velocity of the system.

Construct rotational modulation while performing directional maneuvers, tied to The direction cosine matrix of the system is , then the attitude angle error equation of the rotating strapdown measurement system becomes: ,but is the identity matrix, so the attitude matrix is still , the superscript of the parameter in the formula indicates the component value in the corresponding coordinate system, and the subscript indicates the coordinate system of relative motion.

in the attitude error equation is the angular velocity error relative to the inertial frame at representation in the system, that is ,in, Scale factor error of the gyroscope: , is the gyro scale coefficient error of the three axes; is the installation error angle of the gyroscope: is a symmetric matrix, that is, three installation error angles , , ; and are the constant drift and random drift of the gyroscope, respectively.

because ,so

, which contains 4 items:

, , and .

the first item

;

item 2

;

item 3 ;

Item 4 .

It is known from items 1-4 that through directional maneuvering and structural rotation motion, the installation error, scale coefficient error and constant value drift will be modulated into a periodic function, which can be solved to 0 after a cycle, which can greatly reduce the error .

In practice, due to the limitation of the carrier performance and the operator's ability to operate, when doing heading maneuvers, the matrix can't be completely , a motion in the pitch or roll direction will occur, i.e. a matrix or , or pitch and roll motions exist simultaneously, i.e. attach a matrix , because these two movements cannot completely construct the rotational movement, that is, the error cannot be modulated, and some errors will be increased, but this part of the increased error can be ignored for the entire system.

In the actual shot, the bullet cannot always move with the carrier, and there must be a time when it is launched. During the autonomous operation, the error of the system cannot be modulated. Therefore, in order to further reduce the error, an error estimation method is designed to compensate for the error during the autonomous movement. .

The error estimation steps include: (1) the missile and the carrier fly together and enter the navigation state; (2) the carrier flies from time to Always conduct heading maneuvers and record inertial navigation error ; (3) in The moment the carrier moves in a straight line, to moment to meet ,Record time inertial error ; (4) In the same time, approximately the same motion external environment, the system error caused by the error of the gyroscope should be the same, but in time to Between moments, the carrier performs maneuvering and rotation modulation, and the error will be greatly reduced, while the error will be large during linear motion. Using the difference between the two to estimate the error caused by the gyroscope per unit time is: , ; (4) If time and conditions permit, repeat the above process, and then take the average.

Since the MEMS gyroscope is mass-produced and has high consistency, the similarity between the error characteristics of the z-axis gyroscope and the error characteristics of the x and y-axis gyroscopes can be compared in advance through the turntable calibration, and the z-axis gyroscope is set The similarity between the error characteristics and the error characteristics of the x and y-axis gyroscopes is and , and then calculate the system error caused by the error of the z-axis gyroscope , which means that the error in that axis is used for the calculation of the larger similarity.

The advantages of the present invention are: (1) the carrier is used to maneuver to realize the rotational motion, the equivalent rotational modulation is constructed, and the error in the direction of the rotation axis is eliminated; (2) the error in the direction of the rotation axis can be assisted to be estimated by using the characteristics of the consistency of the MEMS gyroscope; (3) The general carrier can maneuver in the direction. The rotation modulation construction method is simple and easy to implement, without additional mechanical structures, and maintains the advantages of small size, low cost, low power consumption and good anti-vibration performance.

Description of drawings

Fig. 1 is the bomb-carrying flight of the present invention;

Fig. 2 is the S maneuver process of the present invention;

Figure 3 constructs the timing process of rotational modulation.

detailed description

The specific embodiment of the present invention is described below in conjunction with accompanying drawing and carrier aircraft (carrier) maneuver.

The micro-inertial measurement system is constructed with MEMS gyroscope TL632B, accelerometer MVS6000 and DSP6713 as the core components of the guidance. Due to the high accuracy of the accelerometer, it can reach more than 0.1 mg, which is sufficient for the requirements of tactical weapons, while the accuracy of the MEMS gyroscope is low, and the constant value The drift is generally more than tens of degrees, although for guided weapons with an effective working time of more than ten seconds to more than one hundred seconds, the error is also fatal, so the accuracy needs to be high, including two aspects: one is the MEMS inertial measurement system itself The accuracy must be high, and the second is that the initial value must be accurate, especially the attitude accuracy.

For the carrier aircraft, it is easy to maneuver before the bomb is dropped. In reality, it also needs to maneuver (especially when it is locked by the opponent's radar). Of course, considering the actual conditions (carrier performance and pilot driving ability), the carrier aircraft is very difficult. It is easy to realize directional maneuvering, but it is difficult for the carrier aircraft to achieve "tumbling" and "rolling" movements in the pitch and roll directions, and can only achieve partial movements, such as the swinging movement of the wings, so it is difficult to rotate in these two axes modulation.

As shown in Figure 1, the aircraft is flying with bombs, and the bombs are hung under the wings.

Regardless of whether the missile is hung under the wing or buried in the cabin, the rotational motion of the missile-borne inertial navigation structure can be rotationally modulated.

If it is buried in the engine room, it will roll when the bomb is dropped, and this rolling process can be used to construct a unidirectional rotational motion. The principle of error modulation is the same as the rotational modulation of the motorized structure.

Use the carrier aircraft to do directional maneuvers and achieve rotational motion to modulate the error of the inertial navigation system of the guided weapon, thereby reducing the error and providing parameters for the transfer alignment and inertial device error estimation and compensation.

Set inertial navigation rotating coordinate system , the carrier coordinate system , the navigation coordinate system , the inertial coordinate system , the earth coordinate system , subscript Indicates the rotating coordinate system, Indicates the aircraft coordinate system, represents the navigation coordinate system, Indicates the inertial coordinate system, Represents the navigation coordinate system.

Set the inertial navigation coordinate system at the initial moment ( ) and the aircraft coordinate system ( ) overlap, and then perform the S maneuvering process shown in Figure 2, that is, the inertial navigation around the z-axis direction at an angular velocity continuous rotation, the The transformation matrix between the moment inertial navigation coordinate system and the navigation coordinate system can be expressed as:

.

The difference between using motorized construction rotation and direct rotation is the inertial navigation coordinate system ( ) and the aircraft coordinate system ( ) has been coincident, that is, to maintain the state of the initial moment.

The attitude angle error model of the MEMS strapdown measurement system is , wherein, as shown in Figure 1, the x-axis is along the longitudinal axis of the carrier, and the z-axis is vertical to the carrier, and the carrier coordinate system is constructed according to the right-handed coordinate system), Indicates the inertial coordinate system, represents the earth coordinate system, In order to calculate the attitude error between the navigation coordinate system and the real navigation coordinate system, and are the angular velocity and the angular velocity error, respectively, is the strapdown attitude matrix, Represented in the navigation coordinate system Intrasystem, Navigation Coordinate System relative inertial coordinate system The rotational angular velocity of the system.

To construct rotational modulation while performing an S maneuver, tied to The direction cosine matrix of the system is , then the rotary strapdown inertial navigation system, the attitude angle error equation becomes: ,but is the identity matrix, so the attitude matrix is still .

, the superscript of the parameter in the formula indicates the component value in the corresponding coordinate system, and the subscript indicates the coordinate system of relative motion, The scale factor error of the gyroscope is: , is the gyro scale coefficient error of the three axes; is the installation error angle of the 3 gyroscopes: is a symmetric matrix, that is, , , ; and are the constant drift and random drift of the gyroscope, respectively.

because ,so

, which contains 4 items: , , and .

the first item

;

item 2

;

item 3 ;

Item 4 .

From items 1-4, it can be seen that through the S maneuver and the construction of the rotary motion, the installation error, the scale coefficient error and the constant drift modulation periodic function will be resolved to 0 after one cycle, which can greatly reduce the error.

Although in reality, the directional maneuver of the carrier aircraft cannot be so perfect, and some additional maneuvers will inevitably be introduced, that is, some errors will be introduced, but it is enough for low-precision inertial navigation to greatly improve the accuracy of the system.

In reality, when the bomb cannot always fly with the carrier aircraft, and must be projected, the error of the system cannot be modulated during the autonomous flight. In order to further reduce the error, an error estimation method is designed to measure the error during the autonomous flight. compensate.

The error estimation timing process shown in Figure 3, the steps of the error estimation method include: (1) the bomb and the carrier aircraft fly together and enter the navigation state; (2) the carrier aircraft flies from time to Carry out S maneuvers at all times, record inertial navigation error ; (3) in Carrying planes for direct flights at all times, to moment to meet ,Record time inertial error ; (4) In the same time, the approximate flight environment, the system error caused by the error of the gyroscope should be the same, but in the time to Between moments, the carrier aircraft maneuvers and performs rotation modulation, the error will be greatly reduced, and the error will be very large during the direct flight. Using the difference between the two to estimate the error caused by the gyroscope per unit time is: , ; (4) If time permits, repeat the above process, and then take the average.

Rotation Since MEMS gyroscopes are mass-produced and have high consistency, the similarity between the error characteristics of the z-axis gyroscope and the error characteristics of the x and y-axis gyroscopes can be compared in advance through the turntable calibration, and the z-axis gyroscope is set The similarity between the error characteristics and the error characteristics of the x and y-axis gyroscopes is and , and then calculate the system error caused by the error of the z-axis gyroscope , indicating that the similarity is calculated with the error of that axis.

Finally, it is explained that the above implementation cases are only used to illustrate the technical solution of the present invention and not to limit. The present invention can be modified or replaced without departing from the scope of the technical solution, which should be covered by the scope of the claims of the present invention.

Claims (4)

1. A construction method of MEMS equivalent uniaxial rotary inertial navigation, it is characterized in that utilize the course maneuver of carrier, as the course maneuver of aircraft S maneuver, ship and vehicle etc., carry out rotational motion, structure inertial navigation equivalent uniaxial Rotate the modulation process to reduce the system error caused by the gyroscope scale coefficient error, installation error and constant value error slow variation and so on. 2. A construction method of MEMS equivalent uniaxial rotary inertial navigation, which is characterized in that if the bomb is embedded in the cabin, when the bomb is launched, rolling motion will occur, and this rolling process can be used to construct the equivalent uniaxial Rotary motion for error modulation. 3. A kind of error estimation method, it is characterized in that estimation step comprises: (1) bomb and carrier run together, enter navigation state; (2) carrier from time to Always conduct heading maneuvers and record inertial navigation error ; (3) in The moment the carrier moves in a straight line, to moment to meet ,Record time inertial error ; (4) In the same time, the approximate external environment of the movement, the system error caused by the error of the gyroscope should be the same, but in time to Between moments, the carrier performs maneuvering and rotation modulation, and the error will be greatly reduced, while the error will be large during linear motion. Using the difference between the two to estimate the error caused by the gyroscope per unit time is: , ; (4) If time and conditions permit, repeat the above process, and then take the average. 4. A z-axis error estimation method is characterized in that because the MEMS gyroscope is produced in batches, it has high consistency, and can compare the error characteristics of the z-axis gyroscope and x, the y-axis gyroscope by the turntable calibration in advance The similarity between the error characteristics, the similarity between the error characteristics of the z-axis gyroscope and the error characteristics of the x and y-axis gyroscopes is and , and then calculate the system error caused by the error of the z-axis gyroscope , indicating that the similarity is calculated with the error of that axis.