EP0319649A1 - Device for the determination of a roll angle - Google Patents

Abstract

A device for determining the roll angle of a missile (10) launched from a tube (20), by means of a first magnetic-field sensor (11) located in or on the missile (10), is described. In known devices of this type, the sensor signal is dependent not only on the roll angle, but also on the flight direction of the missile (10). To obtain a definite angular relation between the missile and the phase of the sensor signal in any flight direction, it is proposed that the missile (10) should have a second magnetic-field sensor (12) located at a predetermined distance in the flight direction. In addition, a reference magnet (21) is provided on the tube (20), so that, when the missile flies past the reference magnet (21), the second magnetic-field sensor (12) generates a reference signal determining the instantaneous angular position of the missile (10). The roll angle can then be determined at any moment from this angular position by means of the detected speed of the projectile. <IMAGE>

Description

The invention relates to an arrangement for determining the roll angle position of a missile departing from a tube, as defined in the preamble of claim 1.

In the case of missiles rotating about their longitudinal axis, it is often necessary to measure the roll angle position of the missile relative to the geodetic reference system. For example, in the case of guided projectiles for the trajectory correction, both the deviation of the actual path from the theoretical path and the roll angle position are determined, in order then to trigger the correction impulse in such a roll angle position that it counteracts the observed deviation (see e.g. DE-0S 25 43 606).

The roll angle position of the missile can be determined both optically and magnetically. An optical roll angle position measurement has the disadvantage that it is sensitive to brightness and therefore z. B. at night or unfavorable environmental conditions (snow, blue sky) only allows incorrect measurements.

When the roll angle position is determined magnetically, there is a magnetic field sensor in or on the missile which determines the roll angle position with respect to the earth's magnetic field, the sensitivity axis of which runs perpendicular to the flight direction. It takes advantage of the fact that the vector of the earth's magnetic field lies only horizontally above the earth's surface near the equator, while it is inclined to the earth in the other areas and therefore has a vertical component that can be used for measuring the roll angle position.

During a flight in the direction of the magnetic north pole, a sinusoidal signal is obtained via the magnetic field sensor due to the missile rotation around the flight axis, the maxima and minima of which are proportional to the magnetic vertical field of the earth, so that an "up-down" determination is possible. However, if the direction of flight deviates from the magnetic north direction, the maximum magnetic field detected by the sensor no longer points vertically downwards but in a direction that is increasingly determined by the angle of inclination. For example, a flight in the east of Germany results in an error of 25 °.

It is therefore the object of the present invention to further develop an arrangement of the type mentioned at the outset such that a clear angular assignment to the phase of the sensor signal is obtained when the missile moves in any direction.

This object is achieved by the features of the characterizing part of claim 1.

Particularly advantageous refinements result from the subclaims.

Further advantages of the invention are explained in more detail below with the aid of exemplary embodiments with reference to figures.

• Fig. 1 eine schematische Darstellung einer erfindungs­gemäßen Anordnung und
• Fig. 2a bis Fig. 2c den Verlauf der Ausgangssignale der Magnetfeld­sensoren in Abhängigkeit der Entfernung des Geschosses von der Rohrmündung.

Show it:

• Fig. 1 is a schematic representation of an arrangement according to the invention and
• 2a to 2c the course of the output signals of the magnetic field sensors as a function of the distance of the projectile from the pipe mouth.

1 shows a missile with 10 and with 20 the muzzle-side part of a tube (for example a cannon) from which the missile 10 is fired. The magnetic field sensors 11 and 12 are located in the interior of the missile 10. These magnetic field sensors can, for example, be sensors that utilize the magnetoresistive effect. The first sensor 11 has only one sensitivity axis perpendicular to the flight direction, while the second magnetic field sensor 12 has two sensitivity axes lying in a plane perpendicular to the flight direction. The corresponding sensors are commercially available and therefore do not need to be explained in more detail.

Furthermore, in FIG. 1, H denotes the field strength of the earth's magnetic field, which can be broken down into a vertical component H _V and a horizontal component H _H. The inclination angle is marked with α, which lies between 60 and 70 ° in the FRG.

The mode of operation of the arrangement according to the invention is briefly described below:

      (1)
wobei Ax und Ay die Amplituden der Teilsensoren, die die Sensorachsen charakterisieren, γ der Winkel zwischen dem in x-Richtung orientierten Teilsensor des Sensors 12 und der Richtung des Referenzmagneten und tx der Zeitpunkt der Messung bedeuten.When the projectile 10 emerges from the tube 20, the rear magnetic field sensor 12 is moved past the reference magnet 21, while the front sensor 11 already detects the earth's field. This enables the phase position of the projectile to be determined with respect to the external magnetic field. Due to the biaxial arrangement of the sensor axes of the sensor 12, the spatial position of the reference magnet 21 within the plane spanned by the two sensor axes can be determined by the following relationship:
tg γ (t _x ) = $\frac{\text{Ay}}{\text{Ax}}$

(1)
where Ax and Ay are the amplitudes of the partial sensors which characterize the sensor axes, γ the angle between the partial sensor of sensor 12 oriented in the x direction and the direction of the reference magnet and tx the time of the measurement.

The reference signal received by the second magnetic field sensor 12 on the basis of the magnet 21 thus determines a specific angular position of the missile, which can be clearly assigned to the signal of the front sensor 11.

These relationships are shown again in FIGS. 2a to 2d. 2a) shows the vertical magnetic field measured with the first sensor 11, where to denotes the time at which the sensor 11 emerges from the mouth of the tube 20 and the sensor amplitude A 11 corresponding to the respective magnetic field on the vertical axis is applied. The voltage amplitudes A _x and A _{y of} the partial sensors of the sensor 12 are shown in FIGS. 2b and 2c. When the reference magnet 21 flies past, there are pronounced maximum values.

In Fig. 2d is that with the help of Eq. (1) determined angle γ reproduced, which is 19 ° in the example shown.

The roll position determination of the projectile at any time on the trajectory is determined on the basis of the following consideration:

The front sensor 11 has an amplitude curve A (t) according to the following relationship:
A (t) = A0 sin (ω₀ t + φ)

The initial phase of this signal can be equated with the angle from the measurement of the two rear partial sensors of sensor 12 (φ = γ). At the same time, their signal (or the amplitude signal A _x ) serves as a trigger for the front sensor 11, which takes its measurement at this point in time and determines the speed ω. The roll position α can be determined from the determined speed ω at any point in time with a known initial phase:
α (t) = ω t + γ (to)
determine.

The angle of attack of the missile changes on a ballistic trajectory, but not the direction of flight. Therefore, only the amplitude of the sensor signal changes and not the phase position, so that the shape of the flight path has no influence on the roll position determination. For the roll position detection, the phase position is thus evaluated according to the invention.

Claims (2)

1. Arrangement for determining the roll angle position of a missile (10) flying out of a tube (20) with the aid of a first magnetic field sensor arranged in or on the missile (10), characterized by the features:
- The missile (10) has a second magnetic field sensor (12) arranged at a predetermined distance in the direction of flight;
- On the tube (20), a reference magnet (21) is provided, so that the second magnetic field sensor (12) when flying past the reference magnet (21) generates a reference signal determining the instantaneous angular position of the missile (10). 2. Arrangement according to claim 1, characterized in that the second magnetic field sensor (12) has two sensitivity axes lying in a plane perpendicular to the direction of flight.

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