Aeronautics and astronautics – Missile stabilization or trajectory control – Automatic guidance
Reexamination Certificate
1983-11-17
2001-07-03
Jordan, Charles T. (Department: 3641)
Aeronautics and astronautics
Missile stabilization or trajectory control
Automatic guidance
Reexamination Certificate
active
06254030
ABSTRACT:
The present invention is related to guidance systems for terminally guided missiles. Specifically, apparatus and method are provided for biasing the trajectory of a guided missile to increase the top attack angle for certain target conditions.
Guided missile weapons have been developed which include proportional guidance in two planes of movement. The proportional guidance control for these systems develops control signals for guiding the missile to a target based upon a sensed line of sight rate with respect to the target. The error information for driving the multiaxis proportional guidance system is developed from a seeker which senses infrared energy, laser energy, radio frequency energy or millimeter wave energy emitted or reflected by the target.
Studies conducted by the inventors have shown that the effectiveness of a terminally guided missile with a shallow approach angle requires that the angle of impact be greater than 45° for many target conditions. The higher angle provides for a greater target penetration by impacting areas of the target such as the engine compartment or exit hatch of a military tank where armor protection is necessarily weak. For other target conditions, such as closing targets moving towards the missile, a lofting trajectory which results in a high angle of attack and large seeker gimbal angles, is undesirable. In view of the foregoing design requirements, a bias to the missile trajectory is desirable for those target conditions which require a lofting terminal trajectory. The bias, however, should not be constant, but only supplied for target conditions which require an improved angle of impact based on sensed line of sight rate with respect to the target, increasing the probability of total target destruction. The condition for establishing the bias should be based on a sensed in-flight target to missile geometric relationship.
SUMMARY OF THE INVENTION
An object of the present invention is to provide trajectory shaping resulting in high impact angles for a terminally guided missile system.
A more specific object of the invention is to provide a trajectory bias operative in response to a sensed missile-target geometric relationship.
These and other objects are provided by apparatus and methods which, in response to a sensed flight condition, biases the missile terminal trajectory to achieve a high impact angle with the target. A guided missile having proportional guidance control developed from a sensed relative target position and velocity is equipped to sense one flight parameter. A bias to the trajectory is established when the sensed flight parameter exceeds a predetermined minimum. Impact angles of a more nearly vertical condition over a wide range of missile/target acquisition geometric conditions are obtained using this triggered bias technique over conventional constant gravity bias proportional guidance technology.
In a preferred embodiment of the invention, the sensed parameter is the missile pitch line of sight rate which triggers first and second bias levels into summation with the missile pitch and yaw forward guidance control signals. The missile bias levels are proportional to the sine and cosine of the roll angle which is detected by on-board instruments during the initial target acquisition phase of the trajectory. The bias levels may also be combined with a gravity bias parameter to further modify the trajectory based upon a predetermined gravity influence related to the missile aerodynamic coefficients.
REFERENCES:
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patent: 3624367 (1971-11-01), Hamilton et al.
patent: 3946968 (1976-03-01), Stallard
patent: 3984072 (1976-10-01), Von Pragenau et al.
patent: 3998409 (1976-12-01), Pistiner
patent: 4062509 (1977-12-01), Muhlfelder et al.
patent: 4234142 (1980-11-01), Yost et al.
Francisco Glen L.
Sloan, Jr. Marlin A.
Buckley Denise J.
Burns Doane , Swecker, Mathis LLP
Jordan Charles T.
Lockheed Martin Corporation
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