Aeronautics and astronautics – Missile stabilization or trajectory control – Automatic guidance
Patent
1983-06-02
1985-07-16
Jordan, Charles T.
Aeronautics and astronautics
Missile stabilization or trajectory control
Automatic guidance
F41G 722
Patent
active
045291519
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method and an apparatus for steering an aerodynamic body, e.g. a missile or projectile, after its firing toward a target. By means of the output signal of a homing device, which signal is a measurement of the instantaneous value of an error angle between a body-fixed axis, preferably the symmetry axis of the body and the line of sight from the body to the target, the body is guided in a flight path toward the target, and in response to a control variable signal which is dependent on the angular rate of the line of sight.
BACKGROUND ART
In prior art missiles having a homing device for determining the error angle .epsilon. between the missile attitude and the line of sight to the target a gyro is employed for determining the attitude angular rate .theta. which is required for calculating the angular rate .sigma. of the line of sight according to a relation
DISCLOSURE OF THE INVENTION
The object of the invention is to provide a method and an apparatus of the kind mentioned by way of introduction for steering a missile without requiring any gyro.
According to the invention this object is achieved by determining on the basis of relationships describing the aerodynamic behaviour of the body with respect to the target, a signal value representing the line of sight angular rate, on the one hand, and a signal value representing the body attitude angular rate, on the other hand. Said two signal values are combined to form a signal value of the error angle. A difference error angle signal value is formed by an error angle measurement received from the homing device and the approximate error angle signal value and is fed back to said aerodynamic relationships in order to update quantities of said relationships.
An apparatus for performing said method is also described.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is described below in greater detail and with reference to the accompanying drawings.
FIG. 1 is a single plane representation of a missile in outline which by proportional navigation is steered toward a moving target for interception thereof, some essential quantities being shown.
FIG. 2 is a one channel schematic block diagram of a prior art system for proportional missile navigation and showing the operation thereof.
FIG. 3 is a one channel schematic block diagram of the invention showing the operation thereof and having a lay-out similar to FIG. 2.
MODE FOR CARRYING OUT THE INVENTION AND INDUSTRIAL APPLICABILITY
The invention is applicable in all types of missiles, e.g. a guided missile or artillery projectile, provided with means to bring about guided deflection. FIG. 1 shows such a missile M moving in a flight path P.sub.M towards a target vehicle T which is moving in a path P.sub.T. It is shown by means of lines of sight S.sub.1 -S.sub.4 in four positions I, II, III and IV how the missile is closing in on the target at the same time as the lines of sight become gradually more parallel as the missile comes closer to the target.
In the position I the missile M has a speed V in the flight direction. .sigma. is the line of sight angle between the line of sight S and an inertial reference direction R. .theta. designates the attitude angle of the missile between a body-fixed axis A, here the axis of symmetry of the missile, and the inertial reference direction R. .epsilon. is an error angle between the body-fixed axis A and the line of sight S. It is seen that the error angle .epsilon. is obtained from the line of sight angle .sigma. and the attitude angle .theta. according to the relationship
FIG. 2 is an operational block diagram of one example of a prior art missile system of the proportional navigation type using a homing device 1'. Any influence on the missile with respect to the missile dynamics, the environment and guided deflection is illustrated by means of a block 3'. Actual values of the line of sight angle .sigma. and the attitude angle .theta. received from the block 3' result in an actual error angle .epsilon.. This latter angle
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patent: 4456862 (1984-06-01), Yueh
Custin James R.
Jordan Charles T.
Nilles James E.
Saab-Scania Aktiebolag
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