RU2256881C2 - Method of estimation of orientation and navigation parameters and strap-down inertial navigation system for fast rotating objects - Google Patents

Abstract

FIELD: instrumentation engineering; orientation systems; determination of linear velocity and angular velocity relative to inertial, geographic and other coordinate systems.

SUBSTANCE: proposed system employs accelerometers for measurement of angular velocity; sensitivity axes of at least two of these accelerometers are oriented in directions not coinciding with direction of axis of fast-rotating object and not orthogonal relative to it; orientation and navigation parameters of fast-rotating objects are obtained taking into account processing of signals from said accelerometers by solving the differential equations with the use of Rodrigo-Hamilton or Keil-Kein parameters. Object motion parameter meters are made in form of five accelerometers, angular velocity sensor and temperature sensor mounted in housing; sensitivity axes of first pair of accelerometers are oriented in one plane with axis of fast-rotating object and are deflected from it in various directions by angle of 45 deg.; sensitivity axes of second pair of accelerometers are oriented in opposite direction in parallel with axis passing through centers of locating holes in housing of object; sensitivity axis of fifth accelerometer is oriented in direction parallel to axis, orthogonal axis of fast-rotating object and axis passing through centers of locating holes found in housing of object; sensitivity axis of angular velocity sensor is oriented along axis passing through centers of locating holes found in housing of object; information outputs of five accelerometers, angular velocity sensor and temperature sensor are connected to microprocessor outputs.

EFFECT: extended range and enhanced accuracy of measurements; reduced overall dimension and low cost of device.

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Description

The present invention relates to the field of instrumentation and can be used in orientation systems that determine the parameters of the object’s movement, in particular displacement, linear velocity, angular velocity relative to inertial, geographical, starting or other coordinate systems.

Orientation systems are used to determine the angular position of a moving object relative to some reference coordinate system. Two methods are known for representing a reference coordinate system on board a moving object: by physically modeling it using, for example, a gyro platform or by analytically calculating it based on measurements of any individual orientation parameters. In the first case, stabilized gyroscopic platforms are used, which communicate three angular degrees of freedom relative to the body of the object using a suspension of one type or another. Depending on the type of moving object and its purpose, the platform can be stabilized relative to inertial space or adjusted relative to the plane of the local horizon and in azimuth. In the second case, a strapdown scheme for constructing an orientation system based on sensors installed directly on the object’s body is implemented. The reference coordinate system is created using a computer by integrating and converting sensor signals. Moreover, the computer simulates in this case cardan suspension of the gyro platform. Orientation systems constructed according to this scheme are called platform-free (see, for example, RF patent No. 20111169, MKI G 01 C 21/00, 1990, RF patent No. 2059205, MKI G 01 C 21/00, 1992) .

When developing fast-moving objects (for example, rockets, fast-rotating shells, inclinometers), the problem arises of determining the parameters of the object's movement, which requires solving additional problems. Inertial navigation systems, which are divided into platform or strapdown, are usually used to solve such problems. The choice of an inertial navigation system depends on the dynamics of the object and a number of operational characteristics and accuracy requirements. Such systems usually consist of three gyroscopes and three accelerometers and contain, if necessary, one-, two- or three-degree gimbal.

The disadvantage of such systems is the large size, the complexity of the device, poor vibration resistance and high price.

A known method for determining the orientation and navigation parameters of moving objects, including measuring linear and angular parameters, determining the orientation parameters of the object relative to the reference coordinate system and determining the coordinates of the object (RF patent No. 2059205, MKI G 01 C 21/00, 1992).

The specified method eliminates the error associated with the rotation of the reference coordinate system.

The disadvantage of this method is that it cannot provide the necessary accuracy in determining the parameters of rapidly rotating moving objects.

Known measuring device for measuring motion parameters (US Patent No. 4,901,565, MKI G 01 C 21/00, publ. 1990).

Its disadvantage is that it cannot be used to solve the navigation problem in the context of expanding the operational characteristics of fast-moving moving objects and limiting the possibilities of measuring movement parameters.

The technical result of this invention is to expand the range and increase the accuracy of measurements, as well as reducing the size and cost of a device that implements a method for determining the orientation and navigation parameters of fast-moving moving objects.

The specified technical result is achieved by the fact that in the known method for determining the orientation and navigation parameters of moving objects, including measuring linear and angular parameters, determining the orientation parameters of the object relative to the reference coordinate system and determining the coordinates of the object, accelerometers are used as angular velocity meters, sensitivity axes of at least two of which are oriented in directions that do not coincide with the direction of the fast axis objects and are not orthogonal to this direction, but the orientation and navigation parameters of fast-rotating objects themselves are obtained taking into account the processing of signals from the indicated accelerometers by solving a system of differential equations using the Rodrigo-Hamilton or Cayley-Kane parameters.

In addition, from the first pair of accelerometers they can receive a signal proportional to linear acceleration along the axis of rapid rotation of the object and the angular velocity around it, from the second pair of accelerometers they can receive a signal proportional to linear acceleration along the axis passing through the centers of the mounting holes in the object’s body, and angular velocity around the axis of rapid rotation of the object, from the fifth accelerometer - a signal proportional to the angular velocity around the axis passing through the centers of the mounting holes in the body of the object, and linear eniyu along an axis orthogonal to the axis of the rapid rotation of the object and the axis passing through the centers of the mounting holes in the body of the object.

In addition, they can additionally use a gyroscope, from which they can receive a signal proportional to the angular velocity around the axis passing through the centers of the mounting holes in the body of the object, which is processed together with the signals received from the accelerometers.

In a measuring device for measuring motion parameters, the indicated technical result is achieved in that in a strapdown inertial navigation system containing object parameter meters connected to a navigation parameter calculator, these object parameter meters are made in the form of five accelerometers, an angular velocity sensor and a temperature sensor installed in the object body moreover, the sensitivity axes of the first pair of accelerometers are oriented in the same plane with the axis of rapid rotation of the object and from are angled from it in different directions by an angle of 45 °, the sensitivity axes of the second pair of accelerometers are oriented in opposite directions in a direction parallel to the axis passing through the centers of the mounting holes in the object’s body, the sensitivity axis of the fifth accelerometer is oriented in a direction parallel to the axis orthogonal to the axis of rapid rotation object, and the axis passing through the centers of the mounting holes in the housing, and the sensitivity axis of the angular velocity sensor is oriented along the axis passing through the centers in the case of the object, while the information outputs of the five accelerometers, the angular velocity sensor and the temperature sensor are connected to the information inputs of the microprocessor.

In addition, a power level detector can be connected to the free input of the microprocessor.

The invention is illustrated by drawings.

Figure 1 presents the kinematic diagram of the navigation system;

Figure 2 - coordinate system associated with the object, and the starting coordinate system;

Figure 3 shows the correspondence of the phases of the roll angle (rotation) and the axes of the accompanying non-rotating trihedron X1Y1Z1;

Figure 4 is a block diagram of a strapdown inertial navigation system.

To ensure the implementation of the method, the following kinematic scheme is applied.

We introduce the coordinate system X O _{binding binding binding} Y Z _{communications} associated with the object:

- the axis Y _b and Z _s lie in a plane parallel to the installation plane of the device passing through the landing pads of the protrusions;

- the axis of X _St perpendicular to the plane Y _St Z _St and directed towards the flight of the object;

- the axis of Y _St passes through the centers of the mounting holes,

where: A1 ... A5 - accelerometers, G1 - gyroscope.

X _St. Y _St. Z _St. - coordinate system associated with the object;

X _article Y _article Z _article - starting coordinate system.

All accelerometers and a gyroscope are rigidly connected to the body of the device, which through its mounting holes is rigidly attached to the body of the object. In this case, the line passing through the centers of the holes determines the directions of the transverse axes of the object (axes of the associated coordinate system of the object).

The sensitivity axes of the accelerometers A1 and A2 are located in the plane X _sw Z _sw and deviated from the longitudinal axis X _sw at an angle of 45 ° (A1 at -45 °, A2 at + 45 °).

This arrangement is chosen so accelerometers to linear accelerations, acting along the X axis when projected onto the _{communication} sensitivity axis accelerometers included in their measuring range. Thus, the signal measured by the accelerometers A1 and A2 will contain information about the linear accelerations acting in the X axis and the _{communication} of the angular velocity about the axis X _binding, due to the high values of this rate.

Accelerometers, sensitivity axes A3 and A4 parallel to axis Y and _{communications} are directed in opposite directions (A3 in the positive direction of the Y axis _{communications,} and A4 - in the negative). The signal from the accelerometers A3 and A4 will contain information about the linear acceleration of the rocket in the direction of the y axis _sv and the angular velocity around the x axis _sv .

A5-axis accelerometer sensitive axis parallel to z and _{communication} is directed in the positive z-axis direction _{communication.} The signal from the accelerometer contains information about the angular velocity around the axis of Y _St directed in the positive direction of the axis of Y _St , and linear acceleration acting along the z axis of _St.

The axis of sensitivity of the gyroscope G1 is directed in a positive direction with _{communication} signal Y axis gyroscope G1 provides information on the angular velocity around the Y axis of the missile _{communication.}

Thus, we got a kinematic scheme, from the sensors of which signals containing information are received:

- a linear acceleration along the X axis of the _{communication;}

- about linear acceleration along the y axis _cb ;

- linear speed of _{communication} z axis;

- about the angular velocity along the axis X _St ;

- an angular velocity axis Y _{communication,}

which allows the use of such a scheme to determine the angular velocity and as a roll sensor.

A device that implements the proposed method is a measuring unit of a strapdown inertial navigation system (SINS), designed to solve the problems of navigation and orientation for objects (missiles, guided missiles), which are rapidly rotating about a certain axis.

The device 10 includes five accelerometers 1-5, one angular velocity sensor 6, rigidly mounted on the device’s body, rigidly connected to the body of the object through its mounting holes (in the transverse directions relative to the longitudinal axis of the object and which is the axis of rapid rotation), temperature sensor 7, a power level detector 8 and a microprocessor 9. The signal from elements 1-8 is fed to the microprocessor 9. The kinematic diagram of the device is shown in figure 1, and the structural diagram in figure 4.

Denote the angles in figure 2 - ψ - course; ϑ - pitch; γ - roll (rotation), as well as U _a1 , U _A2 , U _a3 , U _A4 , U _A5 - signals from accelerometers A1, A2, A3, A4 and A5, respectively.

The output signals from the accelerometers A3 and A4 are characterized by a system of equations:

where: K _a - scale factors of accelerometers

λ is the radius of the position point of the measuring mass of the accelerometer relative to the axis of rotation.

ω _{x, y, zcb} - projection of the angular velocity of the object on the axis of the object.

a _{x, y, zcb} - projection of the acceleration of the movement of the object on the axis of the object.

When adding the equations we get:

when subtracting:

Where:

The output signals from the accelerometers A1 and A2 are characterized by a system of equations:

When adding the equations we get:

where from:

When subtracting:

from where we determine a _zcb :

The output signal from the A5 accelerometer is characterized by the equation:

Where is determined by _ZCB .

The angle γ is determined by analyzing the modulation of gravitational acceleration, g, present in the signal of each accelerometer.

The projections of the angular velocity ω _YCB and ω _ZCB are equal to its projection on the sensitivity axis of the gyroscope in the phases of the angle γ:

at γ = 0 ° → ω _YCB ;

at γ = 90 ° → ω _ZCB ;

at γ = 180 ° → _{-ω YCB} ;

at γ = 270 ° → _{-ω zcB} .

The diagram presented in Fig. 3 shows the correspondence of the phases of the angle γ and the axes of the trihedron X ₁ Y ₁ Z ₁ , the projections of the angular velocity onto which are measured by the angular velocity sensor (gyroscope).

The axis of sensitivity G coincides with the axis Y _{1 of the} accompanying non-rotating trihedron X ₁ Y ₁ Z ₁ .

Further, on the basis of the obtained data, the orientation and navigation problem is solved using the Rodrigo-Hamilton or Cayley-Kane equations (see, for example, A.Yu. Ishlinsky. Orientation, gyroscopes and inertial navigation. “Science.” 1976, p. 599- 600, pp. 604, 611-619).

Thus, the proposed inventions ensure the achievement of a technical result, which consists in expanding the range and increasing the accuracy of measurements, as well as reducing the size and cost of a device that implements a method for determining the orientation and navigation parameters of fast-moving moving objects.

Claims (4)

1. A method for determining the orientation and navigation parameters of fast-moving objects, including measuring linear and angular parameters of the object’s motion, determining the orientation parameters of the object relative to the reference coordinate system and determining the coordinates of the object, characterized in that accelerometers are used as angular velocity meters, the sensitivity axis of each of which oriented in a direction that does not coincide with the direction of the axis of rapid rotation of the object, while from the first pair of accelerometers receive al proportional to linear acceleration along the axis of rapid rotation of the object and the angular velocity around it, from the second pair of accelerometers receive a signal proportional to linear acceleration along the axis passing through the centers of the mounting holes in the body of the object, and angular velocity around the axis of rapid rotation of the object, from the fifth accelerometer receive a signal proportional to the angular velocity around the axis passing through the centers of the mounting holes in the body of the object, and linear acceleration along an axis orthogonal to the fast axis rotation of the object, and the axis passing through the centers of the mounting holes in the body of the object, and the orientation and navigation parameters of fast-rotating objects themselves are obtained after processing signals about the values of angular velocities and linear accelerations from these accelerometers using the Rodrigo-Hamilton or Cayley-Kane equations. 2. The method according to claim 1, characterized in that it additionally uses a gyroscope, from which a signal is obtained proportional to the angular velocity around the axis passing through the centers of the mounting holes in the body of the object, which is processed together with the signals received from the accelerometers. 3. A strap-down inertial navigation system for fast-moving objects, comprising object parameter meters connected to a navigation parameter calculator, characterized in that the object parameter meters are made in the form of five accelerometers, an angular velocity sensor and a temperature sensor installed in the object’s body, and the sensitivity axes of the first pair of accelerometers oriented in the same plane with the axis of rapid rotation of the object and deviated from it in different directions by an angle of 45 °, the axes are sensitive The second pair of accelerometers are oriented in opposite directions in a direction parallel to the axis passing through the centers of the mounting holes in the object body, the sensitivity axis of the fifth accelerometer is oriented in the direction parallel to the axis orthogonal to the axis of fast rotation of the object, and the axis passing through the centers of the mounting holes in the body and the sensitivity axis of the angular velocity sensor is oriented along the axis passing through the centers of the mounting holes in the object’s body, while the information output five accelerometers, angular velocity sensor and a temperature sensor connected to data inputs of microprocessor. 4. The system according to claim 3, characterized in that a power level detector is connected to the free input of the microprocessor.

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