JPH0131568B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inertial platform.

There are many types of inertial platforms, and each different type is intended to operate under a specific set of conditions. One pole has a platform with three or perhaps four gimbals, with the necessary stabilization gyros and a set of accelerometers on the inner gimbals. This type of platform is very complex and expensive from a mechanical standpoint, requiring slip ring connections and gimbal bearings, and is of large size and weight. At the other end of the spectrum are gyroscopes and accelerometers rigidly attached to the structure of the vehicle.
Although this device is more robust and mechanically simpler, the computational complexity is considerable.

Since neither of the two options mentioned above are particularly cheap, a simple, low cost inertial platform is required. The purpose is to provide such a platform.

According to the present invention, a frame arranged to be fixed to a vehicle, an outer gimbal supported from the frame around a first gimbal axis, and a second gimbal axis perpendicular to the first gimbal axis an inner gimbal supported from an outer gimbal around the gimbal, a pick-off and torque motor for each gimbal axis, and a gyroscope mechanism fixedly mounted on the inner gimbal and having three mutually perpendicular sensitive axes; The platform is in operation, comprising a number of accelerometers mounted on an inner gimbal and having sensitive axes parallel to some or all of the sensitive axes of the gyroscope mechanism, and circuitry including an integrator circuit and a resolver circuit. When the first gyroscope mechanism
and maintaining the inner gimbal in an attitude in which the first and second sensitive axes of the gyroscope mechanism are horizontal and the third sensitive axis is vertical by the joint action of the output of the second sensitive axis and the torque motor; The heading of the aircraft is determined from the output of the third sensitive axis of the gyroscope mechanism via an integral circuit, and the heading of the vehicle is determined from the output of the third sensitive axis of the gyroscope mechanism and each output of the accelerometer using an integrating circuit and a resolver circuit. An inertial platform is provided which is characterized in that the absolute position and velocity of the vehicle are determined, and the pitch angle and roll angle are determined from the output of the pick-off using a resolver circuit.

The invention will now be described with reference to the accompanying drawings.

Referring to FIG.
A frame schematically shown at 0 supports the outer gimbal 11 for rotation about an axis 12. A pick-off 13 and a torque motor 14 for controlling the attitude of the outer gimbal with respect to the frame 10
is installed. The outer gimbal 11 supports the inner gimbal 15 for rotation about an axis perpendicular to the axis 12. The inner gimbal has a pick-off 1 that controls its attitude with respect to the outer gimbal 11.
7 and a torque motor 18 are attached.

The inner gimbal 15 forms a platform on which a gyroscope with three sensitive axes is mounted. As shown in FIG. 1, the first gyroscope 19 has two mutually perpendicular sensing axes, both axes being
is parallel to the plane of The second gyroscope 20 is arranged perpendicularly to the two sensitive axes of the gyroscope 19.
It has a book sensitivity axis. Each gyro has a conventional pick-off and torquer on each sensitive axis.

The inner gimbal also contains the accelerometers needed to provide output from the platform. Two accelerometers 21 and 22 are shown having sensitive axes aligned with the sensitive axis of the two-axis gyro 19.

The various electrical connections to and from the platform are shown schematically in FIG. 2, which shows a diagram of the necessary circuitry to provide these connections.

The pickoff signal from the two-axis gyro 19 is applied to separate servo amplifiers 30 and 31. The outputs of these amplifiers are applied to respective torque motors 14 and 18 on the inner and outer gimbal axes. The outputs of the corresponding gimbal pickoffs 13 and 17 are applied to a central processing unit 32 which derives pitch and roll outputs. This processing device also provides power to the torquers on the two shafts of the gyro 19.

The second gyro 20 has its pick-off and torquer connected in the form of a conventional capture loop. The pickoff output is connected to an integral encoder 34 via a capture amplifier 33. The output of this encoder is applied to both the processing unit 32 and the torquer of the gyro 20.

The two accelerometers are connected in the same way as the gyro 20. The output of accelerometer 21 is applied to integral encoder 36 via capture amplifier 35. The output of the encoder is applied to the processing unit 32 and the force coil of the accelerometer 21. Similarly, the pickoff output from accelerometer 22 is applied to integral encoder 38 via capture amplifier 37. The output of the encoder is applied to the processing unit 32 and the force coil of the accelerometer 22.

The functionality of processing device 32 is schematically illustrated in FIG. This drawing shows the input and output from the processing device shown in FIG. 2, and represents the functions to be performed. Many of these are common in the inertial platform field and need not be explained in detail. This function can be performed by hardware or software.

Referring to FIG. 3, the pickoff output from the gyro 20 of FIG. 2 is applied to a capture amplifier 33 and an integrator 34 which produces an output representing the increment in azimuth of the platform relative to some reference. . This signal is applied via input A of the processing unit to another integrator 40 whose output is the absolute azimuth of the platform, i.e.
Indicates the heading H. A correction signal is applied to integrator 40 as described below.

The two accelerometers 21 and 22 of FIG. 2 also have capture loops containing integrators whose outputs are connected to inputs B and C of the processing unit.
join. Assuming that axes 12 and 16 in FIG. 1 represent the X and Y directions, respectively,
The output of integrator 36, applied to input B, represents the incremental velocity in the X direction, and the output of integrator 34, applied to input C, represents the incremental velocity in the Y direction. Subsequent integrators 41 and 42 produce respective outputs representing the total velocity in the X and Y directions. These are transformed by an azimuth resolver 43 which produces outputs representing northward velocity and eastward velocity.
Resolver 43 has an input from integrator 40 and performs a continuous conversion of the X and Y velocities applied to them as a function of platform heading.

The northerly velocity and easterly velocity from resolver 43 are applied to a conventional Schural Loop circuit 44 which provides output signals representative of latitude LA and longitude LO along with northerly velocity NV and easterly velocity EV. The input CR to the Schular loop circuit 44 may provide correction for gyro drift, instrument bias, etc., and the output from that circuit 44 provides the azimuthal rate of change correction for the integrator 40 previously described. These corrections are conventional and concern the rotational speed of the earth and the speed of the vehicle. The outputs from the processor are required for the torquers of gyro 19 in FIG. 1 and are available at D and E. These are resolver 4
Another orientation resolver 45 that performs the opposite function to 3.
The signal is extracted from the Schular loop circuit 44 through the .
Resolver 45 derives the necessary X and Y gyro torque signals from the modified Schular loop output.

Signals from two gimbal pickoffs 13 and 17 are applied to inputs F and G of the processing unit. This is coupled to a third resolver 46 along with a fixed quantity in an integrator 40 representing the angle in the horizontal plane between the platform's XY axes and the pitch-roll axis of the vehicle.
added to. This resolver converts the X and Y outputs from the pickoff to pitch and roll angle outputs from the processing unit.

The three resolvers and Schular loop circuits are
A fairly simple exchange operation of the type well known in the inertial navigation field is performed. Such conversions are explained in detail in many reference books, so they will not be explained further.

As mentioned above, the functionality of the processing device can be provided either by circuitry or by programming. The desired results may be obtained by methods different from those described. The three sensitive gyroscope axes may be provided by three individual single axle gyroscopes or two biaxial gyroscopes with one redundant axis. A third accelerometer may be provided if desired. Two gimbal pickoffs 13 and 17 are only required if the platform is required to provide outputs indicative of pitch and roll angles. Rather than having the processing unit operate on integrated increments,
It could be used to resolve velocity increments.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the platform showing the hardware arrangement, FIG. 2 is a block circuit diagram of the platform circuitry and other components, and FIG. 3 is a diagram showing the operation of the circuitry. 10...Frame, 11...Outer gimbal, 13,1
7... Pick-off, 14, 18... Torque motor, 15... Inner gimbal, 19... First gyro, 20... Second gyro, 21, 22...
Accelerometer, 30, 31... Servo amplifier, 33,
35, 37...Capture amplifier, 34, 36, 38...
...integral encoder, 32...processing device.

Claims (1)

[Claims] 1. A frame arranged to be fixed to a vehicle, an outer gimbal supported by the frame around a first gimbal axis, and a second gimbal perpendicular to the first gimbal axis. an inner gimbal supported by an outer gimbal around an axis; a pick-off and torque motor for each gimbal axis; a gyroscope mechanism having three sensitive axes fixedly attached to the inner gimbal and perpendicular to each other; When the platform is in operation, the platform comprises a number of gimbaled accelerometers with sensitive axes parallel to some or all of the sensitive axes of the gyroscope mechanism, and circuitry including an integrator circuit and a resolver circuit. , the first and second sensitive axes of the gyroscope mechanism are horizontal and the third sensitive axis is vertical due to the joint action of the outputs of the first and second sensitive axes of the gyroscope mechanism and the torque motor. Maintaining the inner gimbal in attitude, the third part of the gyroscope mechanism
The heading is determined from the output of the third sensitive axis of the gyroscope mechanism through an integral circuit, and the absolute position and speed of the vehicle are determined using the integral circuit and resolver circuit from the third sensitive axis of the gyroscope mechanism and each output of the accelerometer. An inertial platform characterized in that pitch angle and roll angle are determined using a resolver circuit from the output of a pick-off. 2 The gyroscope mechanism has first and second
A platform according to claim 1, comprising a first gyroscope with a sensitive axis and a second gyroscope with a third sensitive axis. 3. The platform of claim 1, wherein the gyroscope mechanism includes three single-axis gyroscopes, each with a separate sensitive axis.