Patent GB-1285722-A (GB)
Title: Advanced fire control system
Inventor: MCADAM WILLIAM ERNEST JR
IPC: F41G5/08
Filed: 1969-08-14
Abstract: 1285722 Sighting HUGHES AIRCRAFT Co 14 Aug 1969 [21 Aug 1968] 40676/69 Heading F3C A gun sighting and fire control system for controlling a vehicle-mounted gun comprises ranging means, gun sights, a computer coupled to the ranging means for developing elevation and deflection signals in earth co-ordinates, and co-ordinate conversion means for sensing the movement of the gun and for developing elevation and deflection lead-angle signals in vehicle co-ordinates. More specifically, the system includes a range finder (e.g. a laser) 10, Fig. 1, and a computer 12 which may be a time-division multiplier. A target detector or fire control sight 14 including a sight drive 16 is provided in a loop which includes the operator for maintaining the target aligned with the sight (sight and laser may be intergrated). The target detector 14 and the gun 20 are linked to one another mechanically or electrically and are also displaced with respect to one another in response to the computer 12 which provides lead angle signals. These are calculated by combining ballistic factors and converting them in a co-ordinate conversion unit 13. The computer responds to standard and nonstandard conditions sensed by a sensor unit 22 which feeds both computer and converter. Other input signls are provided manually from a control unit 24 which may include fire control and angular-rate sampling. An external loop includes an operator 30, Fig. 2, observing a line of sight (LOS) and controlling a hand unit 38 which supplies commands to the computer and power-supply unit 54. Gun 56 is controlled by a gun-and-turret drive unit 58 and applies information to a co-ordinate converter 60 which includes a vertical-angle sensor and a resolver. Gun and sight elevation sensors 62, 64 are responsive to gun and sight drives for electrical linkage of gun and sight. An alternative mechanical link 66 may connect sight 36 and gun 56. The sight 36 responds to the sight drive unit 68 applying both azimuth and elevation drive signals thereto and may provide an optical path for a laser range-finder 56 which may be mechanically coupled to the sight 36. A laser range-finder control unit 70 applies range and range-valid signals to a computer control unit 74. The range-finder 56 also receives logic signals from the control unit 70. A sensor unit 78 senses wind, temperature, tube-wear or equivalent full charge (EFC) and droop as non- standard conditions, these being fed as indicated either to the control unit 74 or computer 54. The control unit 74 supplies the information shown (including hand-set nonstandard conditions) to the computer 54 which also receives rate signals from the angular rate sensors 82. Drive commands from the hand-control unit 38 are applied to the sight for a director system and to the gun and turret drive for a disturbed or non disturbed type system. The azimuth and elevation lead angles from the computer 54 are applied to the gun for a director type system, to the sight for a disturbed type system and to both sight and gun for a non disturbed type system. In the director system of Fig. 4, an operatior uses control unit 128 to maintain coincidence between a LOS 32 and a cross-hair sight line 34 whereby rate commands are applied to a summing unit 130 in combination with measured rate signals from a sight gyro 132 to apply drive signals to a sight drive 134. A computer and control unit 96 receives range signals from a range-finder 56, rate signals fron unit 128 and nonstandard condition signals from sensors 78. Sight position signals are fed to a summing unit 150 which develops a gun sight displacement angle fed to a summing unit 142 which also receives lead angle information from the computer 96. Rate commands are fed to a summing point 154 in a loop which includes gun-and-turret motor and a gun gyro 160. The motor unit 106 also delivers signals to summing point 150 included in a second loop The line 166 indicates an alternative source of measured rate information signals. In the disturbed/nondisturbed system of Figs. 5, 6, an operator 206 observes the angular difference between a LOS 202 and a tracking line through sight 204, and operates elevation command potentiometer 224 and azimuth command potentiometer 226. These provide signals on lines 228, 230 to gun drive unit 290 and turret drive unit 292 respectively. A lead-lock control switch may be used to apply a signal to line 234. The gun drive unit 290 drives gun 56 in elevation and includes an integrator 296, a summing amplifier 300 and a motor 302. A gyro unit 306 responds to gun elevatiion to apply a feedback term to integrator 296. The azimuth control is similar to the elevation control. Since gun and turret are stabilized, hand-control outputs 228, 230 represent gun and turret rate commands and these are fed to the computer and control unit 96 which includes a lead-lock switch responsive to a signal on line 234. The rate command signals are multiplied in unit 252 by a time-of-flight signal t f  and applied to lead-angle summing units 258, 260. In response to range and non- standard condition information on leads 221, 223, a computing unit 264 determines in earth co-ordinates an azimuth signal #, an elevation signal # and a time of flight signal t f . A coordinate conversion unit 268 includes a vertical gyro or pendulum 269 on the gun, and a resolver unit 270, 272 to apply elevation E c  and azimuth D c  signals in turret co-ordinates to amplifiers 258, 260. Additional sensed information such as parallax, droop and jump is applied on leads 276, 278 to the amplifiers 258, 260 which develop total elevation E and azimuth D lead-angle signals. These are applied to the sight drives 214, 216. A linear transducer 358 responsive to azimuth movement applies a feedback signal to the azimuth sight drive 216. A synchro or resolver unit 324 responsive to gun elevation feeds a signal through synchro or resolver unit 362 which is responsive to sight elevation to apply a feedback signal to the drive 214. The lead angles E, D are also applied through switches 340 to the amplifiers 300, 314 of the gun and turret drives 290, 292. Lines 370, 372 indicate alternative sources of rate information for the computer 96. For single gyro operation, a lead 372 is coupled from gyro 320 through the switch 250 multiplier 252, lead 378, summing unit 390 to the resolver 272 (254, 256 not utilized in this case). A director type system in which the computer controls the sight and the gun follows the sight is described with reference to Figs. 7, 8 (not shown), which are slightly modified versions of Figs. 5, 6. A system which is nondisturbed in elevation and disturbed in azimuth is described with reference to Figs. 9, 10 (not shown), again similar to Figs. 5, 6. In the nondisturbed elevation control system of Fig. 11, an angular LOS input is fed to summing point 600 together with a tracking signal from loop 602 which includes an integrator 601. In response to the comparison, a controller 604 provides a control signal w c  which is applied to summing point 608 and to a computer 610 where it is multiplied by a time-of-flight signal t f  to provide a lead angle signal E. A gun-stabilizing loop 618 includes a rate gyro 615 and applies a signal to summing point 608. The output of summing point 608 is applied through an integrator 613 to a summing point where it is combined with the signal E and fed to gun drive 622. The loop 618 also includes a further integrator 628 and a summing point 624 to which is applied a tank-motion signal (if any). A sight loop 634 includes a mirror drive 638 which applies a tracking rate signal to the loop 602 and to the integrator 642 for development of sight angle signal E s . Nondisturbed operation of the azimuth channel is described with reference to Fig. 12 (not shown). A director type fire control system is described with reference to Figs. 13, 14 (not shown). In this, when a target is tracked, a prediction angle is computed from the data and the gun aimed with respect to the sight. The system has a sight loop (681), a gun loop (683), and a gun stabilization loop (685) in the elevation dimension, and has a sight loop (687), a turret loop (689) and a gun stabilization loop (691) in the azimuth dimension. Gyros (693, 695) stabilize the respective sight loops (681, 687). A system which is disturbed in azimuth and nondisturbed in elevation is described with reference to Fig. 15 (not shown). The various sensors of the system provide data in one of two co-ordinate systems, i.e. local earth and turret, and these co-ordinate systems are described in detail with reference to Figs. 16A, 16B (not shown). A mechanization scheme for reducing data to elevation lead angle E and azimuth lead angle D is shown in Fig. 17. A standard value box 651 calculates all lead angles (see Fig. 16) with respect to some predetermined independent variables and such target-dependent variables as wind velocity, target velocity and range. These outputs are operated on in a non-standard value box 652 by the variations in the independent variables. The summed outputs give earth-co-ordinate lead angle signals #, # which are converted in box 653 to turret co-ordinate signals. The latter are connected for parallax P, jump J, boresight (misalignment) B and droop (bending of barrel) D b , to give corrected lead angle signals E. D, The Specification discusses in detail the coordinate conversion system, which is of conventional nature, and the various approximation techniques for applying variations to obtain non-standard values of the dependent variables. The particular approximations used and the mode of application are disclosed in detail in the Specification and are the same as those described in Specification 1,277,251. The Specification also discloses some details of a sight which may be either stereoscopic or non- stereoscopic (Figs. 19, 20, not shown). The sights include provision for ni