System for eliminating gyro on-off drift effects

Claim 2

In an instrument gyro system having a gyro wheel and a synchronous motor with solid rotor for driving the gyro wheel, the gyro system being characterized by a drift rate that remains uniform during a given synchronized period, and that is different in random manner for succeeding on-off gyro operations, the method of eliminating the error-effects of the aforesaid on-off gyro drift that comprises, supplying an alternating voltage to the motor while producing a timing pulse train of frequency higher than the motor supplied frequency, shifting periodically the phase of the supply voltage by periodically suppressing a pulse of the timing train, and timing the voltage phase shift by controlling the duration of the suppressing pulse, for repetitively causing re-synchronization of the supply voltage field and the rotor at spaced points respectively, along the rotor periphery whereby the field slowly precesses around the rotor.

Claim 3

The method as specified in claim 1, wherein the periodic phase shift causes re-synchronization in equally spaced steps around the rotor periphery.

Claim 4

The method as specified in clAim 1 wherein periodic phase shift is achieved by changing the duration of a pulse following a given train of pulses of the supply voltage.

Claim 5

The method as specified in claim 2 wherein the phase of the motor supply voltage is shifted 90* for causing shift of the field 45*, mechanical, with reference to a fixed point on the rotor.

Claim 6

The method as specified in claim 3 wherein the change in pulse duration is 90* electrical.

Claim 7

A control system including an instrument gyro having a gyro wheel and a synchronous motor with solid rotor for driving the gyro wheel, the gyro being characterized by a drift rate that remains uniform during a given synchronized period, and that is different in random manner for succeeding on-off gyro operations, said control system comprising means for supplying alternating voltage to the synchronous motor, and modifying means connected to the voltage supply means for repetitively producing a phase shift in the supply voltage, the modifying means including phase-shift timing means for causing the supply voltage field to precess slowly around the rotor for suppressing the error-effect of the aforesaid on-off gyro drift wherein the voltage supply means includes means for producing a timing pulse train, and the phase shifting means comprises means for periodically suppressing a pulse of the timing train, and means controlled by the so-modified pulse train for producing a phase-shifted alternating current.

Claim 8

A control system including an instrument gyro having a gyro wheel and a synchronous motor with solid rotor for driving the gyro wheel, the gyro being characterized by a drift rate that remains uniform during a given synchronized period, and that is different in random manner for succeeding on-off gyro operations, said control system comprising means for supplying alternating voltage to the synchronous motor, and modifying means connected to the voltage supply means for repetitively producing a phase shift in the supply voltage, the modifying means including phase-shift timing means for causing the supply voltage field to precess slowly around the rotor for suppressing the error-effect of the aforesaid on-off gyro drift wherein the voltage supply means includes means for producing a timing pulse train, and the phase shifting means comprises means for periodically suppressing a pulse of the timing train, and means controlled by the so-modified pulse train for producing a phase-shifted alternating current.

Claim 9

A control system including an instrument gyro having a gyro wheel and a synchronous motor with solid rotor for driving the gyro wheel, the gyro being characterized by a drift rate that remains uniform during a given synchronized period, and that is different in random manner for succeeding on-off gyro operations, said control system comprising means for supplying alternating voltage to the synchronous motor, and modifying means connected to the voltage supply means for repetitively producing a phase shift in the supply voltage, the modifying means including phase-shift timing means for causing the supply voltage field to precess slowly around the rotor for suppressing the error-effect of the aforesaid on-off gyro drift, wherein the voltage supply means includes means for producing a timing pulse train of frequency higher than the motor supplied frequency, and the phase shifting means comprises means for periodically suppressing a pulse of the timing train, and pulse responsive circuitry controlled by the so-modified pulse train for producing a phase shifted, two-phase, alternating current supply voltage for the gyro motor.

Claim 10

A control system including an instrument gyro having a gyro wheel and a synchronous motor with solid rotor for driving the gyro wheel, the gyro being characterized by a drift rate that remains uniform during a given synchronized period, and that is different in random manner for succeeding on-off gyro operations, said control system comprising means for supplying alternating voltage to the synchronous motor, and modifying means connected to the voltage supply means for repetitively producing a phase shift in the supply voltage, the modifying means including phase-shift timing means for causing the supply voltage field to precess slowly around the rotor for suppressing the error-effect of the aforesaid on-off gyro drift, wherein the voltage supply means includes means for producing a timing pulse train of frequency higher than the motor supplied frequency, and the phase shifting means comprises means for periodically suppressing a pulse of the timing train, and pulse responsive circuitry controlled by the so-modified pulse train for producing a phase shifted, two-phase, alternating current supply voltage for the gyro motor.

Claim 11

A control system as specified in claim 7 wherein the pulse responsive circuitry consists of multiple flip-flops inter-connected for producing the two-phase supply voltage.

Claim 12

A control system as specified in claim 7 wherein frequency dividing means is connected to the voltage supply means for producing a comparatively low frequency suppressing pulse, and electronic gating circuitry is jointly responsive to the suppressing pulse and to the timing pulse train for producing the modified pulse train.

Claim 13

A control system as specified in claim 9 wherein the duration of the suppressing pulse is controlled in relation to the duration of a suppressed pulse by a one-shot multivibrator having a time-constant control.