Stabilized optical sighting system

• US 5,867,317 A
• Filed: 09/19/1996
• Issued: 02/02/1999
• Est. Priority Date: 09/19/1995
• Status: Expired due to Fees

• Current Assignee: Sagem SA (Safran SA)
• Original Assignee: Sagem SA (Safran SA)
• Inventors: Le Cardinal, Jean-Yves, Elie, Philippe
• Primary Examiner(s): NGUYEN, THONG Q
• Application Number:
  US08/715,703
• Time in Patent Office: 866 Days
• Field of Search: 359/554-557, 359/900, 250/871-876, 250/203.1, 250/203.2, 250/203.6, 33/230-240, 33/275 R
• US Class Current: 359/555
• CPC Class Codes: F41G 3/22 for vehicle-borne armament, e.g. on aircraft

Abstract

The sighting system has a sight including an aiming mirror (16) which is steered about a circular axis that is fixed relative to a support secured to a carrier, and about an elevation axis (18) under the control of motors (15, 22) to bring the direction of light which is received along a reference sighting line in a geographical frame of reference (x, y, z) to the direction of the circular axis, and measurement device for measuring the real angles imparted to the aiming mirror (16) about circular and lateral axes by the motors. A gyro unit continuously delivers angles for converting the reference frame of reference (x, y, z) to a frame of reference tied to the support (x1, y1, z1). A computer and servo-control unit controls the motors (15, 22) on the basis of information received from the gyro unit (60) and from the measurement device. This unit is designed to compute and transmit to a user device the real position of the sighting line on the basis of information supplied by the measurement device and on the basis of stored parameters modelling at least the optical and mechanical defects of the sight.

Claims

1. A stabilized sighting system having:

sight means including an aiming mirror apt to be steered by control motors about an elevation axis and about a circular axis, said circular axis being relative to a support, said control motors being driven for deflecting a light beam received along a set sighting line in a geographical frame of reference (x, y, z) by amounts such that said beam is directed along the circular axis,

measurement means for measuring real angles imparted to said aiming mirror by said control motors about said circular axis and about an elevation axis,

a gyro unit carried by said support and arranged for continuously supplying data enabling conversion of an angular position in the geographical framer of reference (x, y, z) to a position in a frame of reference tied to said support (x1, y1, z1); and

a computer and servo-control unit for computing an actual angular position of the sighting line from information provided by said measurement means and from stored parameters modelling at least optical and mechanical defects of the sighting system, for transmitting said actual angular position to a user device and for controlling said control motors based on information received from said gyro unit and from said measurement means.

2. A system according to claim 1, for panoramic surveillance at constant elevation and at substantially constant azimuth scanning rate, wherein said sight device has a strip of optoelectronic sensors having a very small angular field of view about said circular axis as compared with a field of view in elevation and said computer and servo-control unit is programmed to generate probe pulses for causing the sensors to be read at instants which correspond to equal angular intervals about the circular axis.

3. A system according to claim 1, further having a lateral control motor for rotating said mirror about a lateral axis and measurement means for measuring real angles imparted by said lateral control motor about the lateral axis, wherein the computer and servo-control unit is programmed to repeat a servo-control and computation sequence in real time to maintain the sighting line at set elevation value and a set azimuth value, each sequence comprising:

(a) computing an angle of rotation about said circular axis assuming that an angle about the lateral axis is zero and servo-controlling the control motor for steering about the circular axis;

(b) computing set values of angles of rotation to be given about the elevation axis and about the lateral axis based on a measured value of an amount of rotation about the circular axis and servo-controlling the elevation control motor and the lateral control motor; and

(c) computing actual values of the elevation of azimuth angles of the sighting line and delivering them to a user module.

4. A system according to claim 3, wherein said user module comprises means for displaying and processing images.

5. A system according to claim 3, wherein the computer and servo-control unit is designed to take account of said stored parameters by performing a product of at least some of a plurality of rotation matrices representing deviation from orthogonality between the elevation axis and the circular axis of the system and parasitic optical deflections due to optical components of the system.

6. A stabilized sighting system for performing panoramic surveillance at a substantially constant set elevation angle, having:

(a) a carrier prone to move angularly in a geographical frame of reference;

(b) sight device including;

a head mounted on said carrier for panoramic movement about a circular axis,

a first motor for rotating said head about said circular axis,

a support rotatable in said head by a second motor about an axis located at a predetermined set angle with said circular axis,

an aiming mirror rotatable by a third motor on said support about an axis orthogonal to said axis having an angle with said circular axis,

light deflecting means fixed in said head for receiving input light reflected by said mirror and deflecting said light along said circular axis,

(c) measurement means for measuring real angles imparted to said mirror by said first, second and third motors;

(d) a gyro unit arranged for continuously supplying data enabling conversion of any angular position in the geographical frame of reference to an angular position in a frame of reference tied to said carrier;

(e) means for deriving set values of the angles to be given to said mirror by said second and third motors for causing an input light beam received along said set elevation angle to be deflected along said circular axis from actual values of the angle about said circular axis and from said data and for driving said second and third motors; and

(f) device for computing an actual angular position of the sighting line within said geographical frame of reference from information provided by said measurement device and from stored parameters modelling at least optical and mechanical defects of the sighting systems and for transmitting said actual angular position to a user'"'"'s device.