Inertial guidance arrangements

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The invention relates to a rigidity control system for determining orientation in the space of an axis of the system and for detecting the position of a movable support structure the system is carried by it.

Such a system is disclosed in U.S. Pat. 749-356 · It is furthermore proposed to use the odometered vehicle in conjunction with compass readings to follow the driver's course.

The aforementioned system is of course very rough and can not be easily used under military field conditions or in other cases where accuracy and time dependence are important factors. In the case of a full-rigged navigation system where two or more gyroscopes and other related equipment are used as used in regular aircraft, these are relatively complicated and expensive. These systems are associated with high costs and greater accuracy than is required for many applications.

The object of the invention is therefore to satisfy this need for a simple inexpensive steering system which delivers healing and course information and is capable of adjusting quickly and when used in a vehicle in connection with an odometer will provide information on both hori -ontal and vertical position of the vehicle during movement.

The invention is based on the recognition that control systems employing only one gyroscope and one-axle gauge can be constructed using a pendulum suspension carrying the two instruments in such a way that the one axis of the system which forms a right angle with the gyroscope's 2 spinneret axis and with the accelerometer's sensitive axis, held in a vertical plane containing the axis whose orientation is to be determined. Furthermore, the suspension suspension was chosen to disconnect the instruments from rolling motion of the vehicle without affecting the detection and monitoring function of the instruments when they provide information about asimut and inclination and thus a continuous indication. of the relocation of the slow-steering system and hence a support structure, usually one-way vehicles in both horizontal and vertical directional components,

This is achieved according to the invention by a platform which is pivotally mounted about an axis whose orientation is to be determined and which is provided with an accelerometer and a gauge with degrees of freedom, wherein the accelerometer's sensitive axis and gyroscopic spinneret axis are oriented in the direction of the first-mentioned axis.

Preferably, the accelerometer's sensitive axis and the gyroscope's spinn axis form the axis whose orientation is to be determined. In practice, the support structure may be a vehicle whose axle front back in the direction of travel is the axis whose orientation scale is determined. In a particular embodiment of the invention, the support structure comprises a projectile firing unit which is mounted on the vehicle where the projectile motion direction directs the axis to be determined.

A further feature of an embodiment of the invention comprises an odometer in the vehicle and an electronic position indicator which receives the signal from the gyroscope accelerometer and odometer, and an angle encoder as output signals representing the angle of the platform slope relative to the support structure. Furthermore, the platform can be boarded if the angular orientation of a vertical axis is the determining possibility of the swingable storage. The mechanism for providing a number of particular angular positions between three predetermined positions in a mutual 90 ° of two is such that the common axis that forms the sensitivity of the accelerometer and the spike axis of the gyroscope falls with the axis whose orientation is to be determined.

As will be apparent from the description below, it goes

for angular displacement relative to the pendulum suspension of one or two additional accurately determined angular positions relative to its standard position. ·. The shuttle suspension strike system comprises two instruments equipped with an angle code for indicating the motion or tipping of the vehicle about the pendulum axis and the use of a damping mechanism has proved advantageous to avoid excessive fluctuations of the shuttle suspension system. When used in a vehicle, the simplified retardation system can be used for an initial calibration of the vehicle's odometer and then the retardation system and the encoder can be used in combination to provide a continuous indication of the position of the vehicle relative to the starting point. The shuttle suspension strike system comprises two instruments equipped with an angle code for indicating the roll or tipping of the vehicle about the pendulum axis and the use of a damping mechanism has been shown to be advantageous in order to avoid excessive fluctuations of the shuttle suspension strike system. When used in a vehicle, the simplified retardation system can be used for an initial calibration of the vehicle's odometer and then the retardation system and the encoder can be used in combination to provide a continuous indication of the position of the vehicle relative to the starting point. The shuttle suspension strike system comprises two instruments equipped with an angle code for indicating the roll or tipping of the vehicle about the pendulum axis and the use of a damping mechanism has been shown to be advantageous in order to avoid excessive fluctuations of the shuttle suspension strike system. When used in a vehicle, the simplified retardation system can be used for an initial calibration of the vehicle's odometer and then the retardation system and the encoder can be used in combination to provide a continuous indication of the position of the vehicle relative to the starting point.

Suitable electronic equipment that can be compared to the presence sensors, ie the gyroscope and accelerometer, can be used for the initial setting, for continuous indication of inclination and adjustment of the retardation system and, if used in conjunction with odometer, may be compensated for errors that may otherwise be introduced. Furthermore, electronic equipment can be used to combine position calculations at the time of starting positions to indicate the position of the vehicle at the moment.

A particular advantage of the system is its ability to wrap unwanted errors by the fatigue tool, together with additional costs and relatively high accuracy,

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An embodiment of the invention will be explained below with reference to the drawings.

Fig. 1 is a perspective view, partly in section, of an axle suspension system according to the invention.

Fig. 2 is a perspective view of a part of Fig. 1.

Fig. 3 is a perspective view of a possible use fortification system of Fig. 1.

Fig. 4 schematically shows the mechanism used to swing the platform carrying the accelerometer and the gyroscopic system of Fig. 1 under the preset setting.

Fig. 5 shows a diagram of the calibration of the system when both the retardation system and an odometer are used for delivery of input signals to the system.

Fig. 6 shows a block diagram of the system of Fig. 1.

Fig. 7 shows a block diagram of the components the right-hand system with associated circuits.

The exemplary embodiment of Fig. 1 has a support structure 11 which, by means of vibration insulators 12, is connected to brackets 13 for attachment in the vehicle or another suitable construction whose orientation and position is to be determined. A shuttle suspension trench unit comprises a rotatable table consisting of a platform 14 which is pendulum suspended by a portion 24 of the support structure 11 in bearings 16 and 18. Platform 14 carries the instruments and bearings forming pendulum shaft 50. Mounted on pivoting platform 14 is gyroscope 20 with two degrees of freedom, an accelerometer disassembled symmetrically about the axis of the pivotal platform 14 relative to the gyroscope 20. and a drive motor 22 which serves for rotation of platform 14 ' relative to the shuttle suspension, but not to rotate part 24 during the initial setting.

A damping mechanism 26 comprising a main cylindrical body 28 is mounted in an oil filled housing 30 and serves to dampen the pivotal movement of the pendulum suspension about the shaft 50 during shock and other high acceleration cases applied to the bracket 13.

An optical code unit 32 may be used for continuous monitoring of the angular orientation of the pendulum suspension 14 in relation to the support structure 11. In those cases when the pivot shaft 50 is in the forward direction of the movement of the vehicle 5, the encoder 32 will provide an indication for lateral winding or rolling of the vehicle. For example, the encoder 32 may be an optical encoder which either provides a smooth signal pattern or a plurality of pulses applied to electronic circuits for continuous indication of angular orientation of the code elements.

Figure 2 shows in a greatly simplified form the way in which the operation is performed, rather than the current construction. The shuttle suspension platform 14 hangs down and turns if the pendulum shaft 50 is formed by the bearings 16 and 18 and located in the vehicle motion direction. On the platform 14, the gyroscope 20seg with its spinneret is in alignment with the sensitivity of the accelerometer 21 and these two axes are parallel to the pendulum axis 50.

It should be noted that the pendelax 50 does not always want horizontal. Eg. As the vehicle moves uphill, the pendulum axis 50 will be oriented at an angle somewhat horizontal and approximately parallel to the inclination angle of the vehicle for the vehicle relative to the horizontal plane.

In order to illustrate the sensitivity of the gyroscope 20 and the accelerator 21, the coordinate axes X, Y and Z are inserted in the platform 14. The spinneret axis of the gyroscope is in the Y-direction. Accordingly, the gyroscope can detect the oscillation of the system about the X-axis and the Z-axis, both perpendicular to the spinal axis Y. Accelerometer 21, in turn, senses accelerations of component components in the Y-direction. Of course, the gyroscope 20 is not sensitive to movement in the Y-direction. When the pendulum shaft 50 lies in the front-rear axis of the vehicle's motion, the accelerometer 21 will measure the inclination angle of the direction of travel of the vehicle, i.e., if the point is below or above the horizontal plane. Asimut, ie, course or change of course, is measured by the gyroscope of the Z ^ axis, Rotation about the X-axis. Corresponds to changes in the slope of the running fabric, for example.

The notches 52, 54 and 56 in the periphery of the platform 14 serve for the initial setting of the system. They incorporate the shuttle suspension platform 14 as it rotates the omen of different specific positions about the vertical axis 58 as described below.

Fig. 5 shows schematically the system in conjunction with the reinforced vehicle 62 equipped with a missile launcher 64. The device 64 is normally oriented horizontally i.e. a rigid connection with the main body of the vehicle 62. However, anhydraulic device 66, 68 may lift the assembly 64 to a desired angle of inclination, the vehicle 62 in Fig. 5 provided with the tightness control unit 70 in accordance with Figures 1 and 2, which is mounted on the rocket launcher 64. The shuttle suspension device 70 is provided with a local electronic controller 72 from which signals are sent to a central data machine 74 on the main body of the vehicle 62.

The shuttle suspension retardation unit 70 provides in formation that is used in two different ways. As the traveling fabric moves and the rocket launcher 64 is connected to the main body of the vehicle, the shuttle axis will be closed with the normal front-rear direction of the vehicle. When the vehicle is stationary, the rocket launcher 64 is directed upwards, i.e. in the firing position as shown in Fig. 5, device 70 will provide both output axis and slope information and also determine changes that may occur due to e.g. firing of an ointment rockets ellerved that the heavy-armed vehicle 62 descends into the ground,

The next to be considered 'is the initial setting used to determine the direction in which pendulum axis 50 points to the ground surface. On the basis of the fact that it is well known that the rotor in a gyroscope will maintain solid orientation in the retardation spindle so that the instrument can detect changes in orientation about its sensitive axes from the exit orientation to the room. While it is commonly acclaimed as a fixed reference, the room can be a single reference determined at the position of solid stars the sky and earth rotation, which is usually 560 degrees in 24 hours.

Accordingly, a gyroscope that senses rotational changes in the ratio of the space rotates accordingly 15 ° per second. hour (in actuality 15.0412 °) by rotation of the earth about its axis. It should also be noted that a single gyroscope located at the earth's equator and having its spin axis pointing north, it will practically not be any effect that affects the gyroscope at the rotation of the earth axis because the gyroscope will continue to point to the sanri.nord when the earth rotates. The initial setting, as described below, uses factors as mentioned above to determine the exact angular orientation of thependent axis. In general, this implies that a measurement of the ground's rotation and other parameters with the gyroscope and accelerator gauge are pointed in one direction and then rotationally distorted at 180 ° relative to the non-rotating shuttle suspension member 24.

These steps and the corresponding mathematical analyzes are included in the initial setting and include the determination of asimut from the earth's rotation will be described below. In the following analyzes, position A is normally used; for rotatable pendulum suspension platform 14 with a sensor roll 84 chopped 56. In position B, platform 14 is rotated 180 ° so that chopped 52 engages roller 84. This rotation is performed by drive motor 22 which is mounted on the rotatable part of the platform 14 and having a small sprocket 86 which engages a larger sprocket 88 which is attached to a central tubular part 25 of the part 24 which does not rotate with the platform 14. The third position C is 90 ° shifted between positions A and B and is determined by chopping 54.

Fig. 4 shows the rotatable platform 14 with the wood chopper 52,54 and 56 and the arresting roll 84. Three microscopes92, 94 and 96 cooperate with a cam 9θ on the platform 14 for providing signals indicating the orientation of the platform in the particular angular orientations when the roller 84 grip in one of the notches. The microswitches stop the engine 22 when the desired angular position A, B or C is engaged and signals this to the system's electronics.

In the mathematical analyzes, the following symbols are used with the indexes A, B and C for measurements taken in positions A, B and C, and the indexes X, Y and Z referring to the direction Y and rotations about the axes X and Z: φ is latitude , which is introduced from the outside of the system, Ω is the earth's rotational velocityω, the rotation speed in radians per. secondA is acceleration ψ is asimut εχ is plant gyroscope levelV is the accelerometer base Θ is slope, ie upward or downward slope of thependent axis ε.er the asymmetry of the gyroscope

• Step 1 - Position A Measurement 'Gyro: ωχΑ, ωχΑ

Accelerometer: ΑγΑ

Step 2 - Position B Measurement: Gyro: ωχβ, ωχΒ

Accelerometer: A, zn 1 ωΧΑ ~ ωΧΒ 2QCOSø

If ψ> 45 °, go to position CωΧΑ + ωΧΒ (1)

A '' AaYA + YB

Θ = SIN -1 aya - ayb2g εζ = ωΖΑ + Q (COScj) SINØ COSiJj - SINø COSØ) (2) (3) (4) (5)

The torque factor of the gyroscope's Z-axis is also calibrated as a result of this rotation a familiar angle. 9

Step 3 ~ Position C is only used if the direction of motion is within 45 ° East or West; Measurement; Gyro ,; ωχ (-.

Calculate motion direction;

ψ = TAN -1

XB (ωχΑ + ωχΒ) + 2 ωχ0 (6)

Fig. 5 is a perspective diagram useful for describing the calibration used in conjunction with the driving tire odometer. When the throttle unit is used in conjunction with the odometer, the pendulum axis is released with the front rearward direction of the vehicle. This will be the case in Fig. 3 when the rocket launcher 64 is in the lowest position and fixedly connected to the main portion of the reinforced vehicle 62, in Fig. 5, the vehicle is assumed to be in point 102 and to move to point 104 along an upward path 106. Horizontal line 102 is the projection of web 106 and extremity 110 of horizontal line 108 has an unidirectional Δ. subsequ below point 104. In practice, course B is from true north to the vertical plane defined by lines 106 and 108 determined initially. In addition, the inclination angle E for the point 104 is the point of departure 102,

During the movement from point 102 to 104, the readometer reads the traveled distance indicated by the accelerometer and the outputs from the gyroscope are used to calculate ΔΧ, ΔΥ and ΔΖ. Then, the path of error of the path of motion, the angle of inclination and the odometer scale factor is determined by the equation of equations 7.8 and 9 below:

Motion Angle ΔΒ = B - TAN "1 M (7) Δα Slope Error Angle -1 A 7 ΔΕ - E TAN \] ---- VAX2 t H2 (8) 10 odometer scale factor

S

A

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1/2 (9) where B ... ·. course from true north at point 104, measured in point 102ΔB. . . . BevegelsesbanefeilvinkelΔΥ. . . . point 104 distance east of point 102Δxx .... point 104 distance north of point 102 E .... angle of inclination of the path of motion over horizon 'plane of plane ΔΕ .... angle of inclination ΔΖ. . . . point 104 distance above point 102Sg. · ... odometer scale sensor .tor · S ^ .... accelerometer scale factor XQ .... distance north calculated from odometer measurements X ^ .... distance north calculated from accelerometer measurementsYq .... distance eastward calculated from odometermålingerY ^ ..,. East distance calculated from accelerometer measurements

Above it is the pendulum suspended retardation unit and its mounting on a movable device such as a driving suit, t together with both the initial setting and the subsequent calibration associated with the output signal from the vehicle odometer. With regard to the accelerometer and gyroscope used in the trench unit, any gyro bucket with two degrees of freedom can be used and an accelerometer with relatively high accuracy. From a practical point of view, brushes have the least possible dimensions. A suitable accelerometer described in U.S. Patent No. 3,498,138. One suitable gyroscope is disclosed in U.S. Patent Application No. 765,239, which describes "mathematics and related equipment for a one-piece gyroscope. In Fig. 6 is the odometer 122 mounted on the frame 124 of the vehicle and the gyroscope 20 "and the accelerometer 21" which forms part of the retardation unit 126 shown as shown. 1. Data from odometer 122, gyroscope · 20 "and axle gauge 21" are supplied to compensators 128, 130 and 132 for treatment in accordance with the mathematical terms of expression.

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The signals from the gyroscope are then transformed into signals such as indicator simulation, slope and rolling in block 134. The output signal block 134 and from the odometer and accelerometer provide distance information as the distance information from the odometered axle selector is converted to standard length and width coordinates in the north and east marker projections. This takes place in blocks 136 and 138. With data for both position and position room, input l40 is indicated the position at the moment of block 142 and a suitable indication or electrical output signal is given.

Figure 6 is actually a function diagram indicating operation mode when both the odometer and the tightness device are used.

Figure 7 is a block diagram of the tensile unit and associated circuits comprising three principal parts divided by vertical straight lines. From left to right erdisse shares the similarity of the retardation unit, II similar to the retardation electronics and the III computer.

The device I comprises an optical scroll decoder 32, the gyro shoe with two sensitivity axes 152 and 154 for the output signal X and respectively. output signal Z. The accelerometer 21 is denotedY-ACCEL indicating that the sensitive axis is in the Y directional sense of course with the pendulum axis 50 in the pull-down heat as mentioned in connection with Fig. 2. The motor 22 drives the rotatable platform 14 on which the gyroscope is mounted for rotation for the initial setting. The damper 156 corresponds to the elements 26, 28 and 30 of FIG. 1. The temperature of the igyroscope, accelerometer and damper is sensed by resistors158, 160 and 162.

The part II comprises a pulses of a rebalancing circuit 164 for the x-ray x ray and a Z-pulse of a rebalancer circuit 166, the temperature signal circuit 168, the rebalancing circuit 170 of the accelerometer Y's pulses and the control unit 172 for the motor. The power supply unit for the drive unit is indicated by 174. The power source forgyroscope and the operation of the spin engine for the gyroscope are marked with 176.

The part III has a pulse input 178, analog-to-digital converter 188 and the controller reference unit 182 which comprises 12 input output circuits. A microcomputer 184 is connected to the line 186 and receives signals from and transmits information to the control reference unit 182. The inputs in the controller reference unit 182 have a latitude input and the mcdu. control input used to select the initial setting, calibration and normal operation of the system.

It should be noted that the function diagram of Fig. 6 and the block diagram of Fig. 7 only serves to illustrate how the trench unit can be arranged in different systems. If another form of gyroscope and accelerometer is used, way to be electronically equal.

Certain mathematical analyzes listed below are useful for limiting 'errors that may otherwise affect the operation of the system unfortunate.

First of all, corrections must be made for the acceleration movement due to acceleration during vehicle movement to avoid the large error source that may occur at the center of axle acceleration when the vehicle is swinging. However, with information from the odometer, this source of error can be corrected from the well-known expressions: -&gt;

Η = CO -&gt;

V in vectors or

A - ω. vz y. -orhvor (10) (11) a ^ = acceleration due to centrifugal forceω = vehicle speed of travel measured by the z-axis of the gyroscope

View - vehicle speed forward A measurement v ^ supplied by the odometer and a measurement ω is provided by a sensitive axis in the gyroscope,

Zl a is calculated, the angle can be;

X can easily be determined from the following expressions: When the acceleration pendulum is offset (12: where g is the gravity of the earth.) 13

The accelerometer can be used during the movement to correct inclination errors and for continuous adjustment of the scale factor of the avodometer to take into account changes in road conditions or the like.

As the system's tilt orientation Θ is determined by mathematical integration of the output signals from the X axis of the gyroscope, the time: where ω x axis. The error due to the basic operation of the gyroscope is increased by zt / \ 0 (t) = Qq j ωχ (t) .J that (13) is the rotation speed of the angle measured by the gyroscope X-

However, the accelerometer also provides a measure of the angle φ (t) relative to the earth's gravity vector g: (14)

By taking mean values ​​of acceleration readings, and independent measurements of Θ, inclination errors can be corrected to the value determined by the accelerometer's basic error. When the vehicle is moved in different terrain, the wheels of wheels or belts may vary and affect the change the scale factor of the odometer. The accelerometer can be used to detect and correct such change of scale factor as usual.

The assumed change of Δνθ for a short term interval measured by the odometer can be expressed as follows: where S is the odometer scale factor,. Ο Λ AVq is velocity change measured by the odometer Δνθ, the assumed velocity change is derived using the predicted scale factor S. o

The assumed change in speed measured by the accelerometer in the same time interval is: vo

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Jto a dty t fertilized (16) 14 of gravity: the measured acceleration in the forward direction of the accelerometer scale factor. o resolved for new assumed scale factor Sq can be obtained: 3 "L_a_.dt- / fertilizer (17 -t Λ Zt a dtV fertilized"&gt; t "

A ΔΥ, using the expression ί · (Ί7) can be achieved where gø is the correction of the acceleration for the inclination angle for elimination

A a is y the vehicle and S era

These two expressions

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rJ s = o

By continuously updating the odometer scale factor,

The pendulum suspension of the reticle assembly according to the invention strives to hold the Z axis of the gyroscope in a plane parallel to the gravity vector and hold the X axis in the gyro shoe horizontally. Furthermore, disconnection of vehicle rolling from the pendulum-mounted platform carrying the instruments is sought. These features enable reduction of the rigidity equipment from two gyroscopes with two degrees of freedom and tension selector to just one gyroscope and one accelerometer. In this manner, using the vehicle modometer, a cheap and relatively accurate equipment is obtained for determining position and orientation without the use of radios or other aids and is not subject to external disturbances. The construction eliminates errors which otherwise mask the accuracy of the system. It is clear that andregyroscopes can be used as f,