GB774483A - Control apparatus for the stabilization of ships - Google Patents

Abstract

774,483. Automatic control systems. MUIRHEAD & CO., Ltd. Aug. 14, 1953 [Aug. 26, 1952], No. 21391/52. Class 38 (4). In a system for automatically stabilizing a ship, a signal dependent on roll acceleration is combined with a signal dependent on roll angle so that the former signal predominates over the latter under conditions of simple harmonic motion, the resultant signal being utilized to advance in phase by not more than 30 degrees a signal, dependent on roll velocity, which is utilized to stabilize the ship. In Fig. 4 a voltage dependent on angle of roll of a ship, produced by a gyro-vertical 5 operating a potentiometer, is added to a voltage dependent on roll acceleration produced by a roll velocity gyro 6 operating a generator 7. The resultant voltage, which is arranged to have the acceleration voltage predominating when the ship is undergoing simple harmonic motion, is applied to a magnetic amplifier 8 the output of which is applied to a winding of a variable inductive device 9 operated by roll velocity gyro 6. Inductive device 9 thus produces an output, dependent on angle of roll and its first and second derivatives, which is utilized to control a servo system (not shown) stabilizing the ship. In a modification, three variable inductive devices, respectively operated by gyro systems responsive to angle of roll, roll velocity and roll acceleration, are arranged to produce a resultant voltage. Gyro systems involving springs and dashpots, eddy current brakes or two restrained gyros mounted on a pivoted platform to produce a movement dependent on roll acceleration are described. Alternatively roll acceleration response may be produced by mass inertia. Relative adjustment of the magnitude of the components of control by varying the gain of magnetic or electronic amplifiers is referred to. Specification 581,776 is referred to.