Tokimec Inc.

Tokyo Keiki Company Limited

Mamoru Akimoto

Takeshi Hojo

Shinichi Kawada

Kazushige Murabayashi

Fuyuki Hane

Michio Fukano

Kanshi Yamamoto

A gyro compass having a gyro case housing therein a gyro and supported with freedom of three axes, functions for outputting a signal corresponding to an inclined angle of the gyro spin axis relative to the horizontal plane, and a function for applying a torque around a vertical axis of the gyro case in proportion to an input signal. A controller is supplied with a signal corresponding to the inclined angle and a latitude value at which the gyro compass is located, and a constant relative to the input latitude value is determined by the controller after the gyro compass is energized. A signal, resulting from differentiating the signal corresponding to the inclined angle during a predetermined time, is added to the product of the signal corresponding to the inclined angle and the constant. This added signal functions as the input signal for the gyro, whereby a constant optimum north-seeking movement is carried out regardless of the change of the latitude value. An error corrector is provided having supplied to it the signal corresponding to the inclined angle, the speed signal of the vehicle and its heading azimuth signal, and a bias error caused by the inclined angle of the gyro compass spin axis and an azimuth error caused by the movement of the vehicle are estimated and calculated to thereby reduce an azimuth error caused by any bias error and the vehicles' movement.

Gyro compass

A gyro compass having a gyro case housing therein a gyro and supported with freedom of three axes, functions for outputting a signal corresponding to an inclined angle of the gyro spin axis relative to the horizontal plane and a function for applying a torque around a vertical axis of the gyro case in proportion to an input signal, and a controller supplied with the signal corresponding to the inclined angle and a latitude value at which the gyro compass is located, wherein a constant relative to the input latitude value is set by the controller after the gyro compass is energized, a signal, which results from differentiating the signal corresponding to the inclined angle during a predetermined time, is added to a signal, which results from multiplying the signal corresponding to the inclined angle with the constant and an added result is set as the input signal, whereby a constant optimum north-seeking movement is carried out regardless of the change of the latitude value to thereby reduce a settle time. Also, the gyro compass having an error corrector supplied with the signal corresponding to the inclined angle, a speed signal of a navigation vehicle and its heading azimuth signal, wherein a bias error caused by the inclined angle of the gyro compass spin axis and an azimuth error caused by the movement of the navigation vehicle are estimated and calculated to thereby reduce an azimuth error caused by the bias error.

A gyro compass having a gyro case incorporating a gyro of which the spin axis is substantially horizontal, a vertical ring disposed around the outer periphery of the gyro case and for rotatably supporting the gyro case around a vertical axis, a follow-up pickup for detecting an angular displacement between the gyro case and the vertical ring around the vertical axis, an accelerometer having an input axis parallel to the spin axis, a vertical torquer mounted on the vertical ring for applying a torque of magnitude proportional to an input signal to the gyro case around the vertical axis, and a control apparatus for receiving an output signal of the accelerometer and for supplying its output to the vertical torquer, in which during a predetermined time after the gyro compass is started to operate, the output signal from the accelerometer is differentiated to produce a differentiation signal which is then supplied to the vertical torquer to reduce a settling time of the north-seeking action.

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Tokyo, Japan

Mamoru Akimoto