Method and apparatus for assessing the coordinates of the centre of a roughly circular form relative to a fixed axis

Claim 1

AN APPARATUS FOR DETERMINING THE CO-ORDINATES OF THE CENTRE OF AN APPROXIMATELY CIRCULAR FORM, SUCH AS THE FORM OF THE SURFACE OF A SHAFT OR A HOLE LYING IN A PREDETERMINED PLANE, RELATIVE TO A PREDETERMINED SYSTEM OF CO-ORDINATES, COMPRISING A FEELER FOR SENSING SAID APPROXIMATELY CIRCULAR FORM, ROTATABLE SPINDLE MEANS MOUNTING THE FEELER FOR ROTATION ABOUT AN AXIS LOCATED WITHIN SAID APPROXIMATELY CIRCULAR FORM IN A KNOWN POSITION RELATIVE TO SAID SYSTEM OF CO-ORDINATES FOR SENSING SAID APPROXIMATELY CIRCULAR FORM, A TRANSDUCER MOUNTED ON SAID SPINDLE AND CONNECTED TO SAID FEELER FOR GENERATING AN ELECTRICAL SIGNAL CONTAINING A FUNDAMENTAL COMPONENT REPRESENTATIVE OF THE ECCENTRICITY OF THE CENTRE OF SAID APPROXIMATELY CIRCULAR FORM, A FILTER CONNECTED WITH THE OUTPUT OF SAID TRANSDUCER FOR SEPARATING SAID FUNDAMENTAL COMPONENT FROM THE REMAINDER OF THE SIGNAL GENERATED BY SAID TRANSDUCER DURING A GIVEN REVOLUTION OF SAID FEELER, SAMPLING MEANS COORDINATED RESPECTIVELY TO EACH OF TWO DIFFERENT SAMPLING POINTS LOCATED 90* APART AROUND THE AXIS OF ROTATION OF SAID FEELER IN A KNOWN POSITION RELATIVE TO SAID SYSTEM OF CO-ORDINATES, MEANS CONNECTING THE OUTPUT FROM SAID FILTER TO EACH OF SAID SAMPLING MEANS, SWITCHING MEANS COORDINATED RESPECTIVELY TO SAID SAMPLING MEANS FOR CONTROLLING THE OPERATING INSTANTS THEREOF, SAID SWITCHING MEANS BEING MOUNTED FOR ACTUATION IN SUCCESSION AT SAID SAMPLING POINTS BY ROTATION OF SAID SPINDLE MEANS, AND MEANS CONNECTED TO THE RESPECTIVE OUTPUTS OF SAID SAMPLING MEANS FOR INDICATING THE RESPECTIVE AMPLITUDES OF SAID FUNDAMENTAL COMPONENT AT SAID LOCATIONS OF SAID DIFFERENT SAMPLING POINTS DURING THE SAME REVOLUTION OF SAID FEELER IN WHICH SAID FUNDAMENTAL COMPONENT IS SEPARATED OUT FROM THE REMAINDER OF THE SIGNAL GENERATED BY SAID TRANSDUCER.

Claim 2

AN APPARATUS FOR DETERMINING THE CO-ORDINATES OF THE CENTRE OF AN APPROXIMATELY CIRCULAR FORM, SUCH AS THE FORM OF THE SURFACE OF A SHAFT OR A HOLE LYING IN A PREDETERMINED PLANE, RELATIVE TO A PREDETERMINED SYSTEM OF CO-ORDINATES, COMPRISING A FEELER FOR SENSING SAID APPROXIMATELY CIRCULAR FORM, ROTATABLE SPINDLE MEANS MOUNTING THE FEELER FOR ROTATION ABOUT AN AXIS LOCATED WITHIN SAID APPROXIMATELY CIRCULAR FORM IN A KNOWN POSITION RELATIVE TO SAID SYSTEM OF CO-ORDINATES FOR SENSING SAID APPROXIMATELY CIRCULAR FORM, A TRANSDUCER MOUNTED ON SAID SPINDLE AND CONNECTED TO SAID FEELER FOR GENERATING AN ELECTRICAL SIGNAL CONTAINING A FUNDAMENTAL COMPONENT REPRESENTATIVE OF THE ECCENTRICITY OF THE CENTRE OF SAID APPROXIMATELY CIRCULAR FORM, A FILTER CONNECTED WITH THE OUTPUT OF SAID TRANSDUCER FOR SEPARATING SAID FUNDAMENTAL COMPONENT FROM THE REMAINDER OF THE SIGNAL GENERATED BY SAID TRANSDUCER DURING A GIVEN REVOLUTION OF SAID FEELER, SAMPLING MEANS COORDINATED RESPECTIVELY TO EACH OF TWO DIFFERENT SAMPLING POINTS LOCATED 90* APART AROUND THE AXIS OF ROTATION OF SAID FEELER IN A KNOWN POSITION RELATIVE TO SAID SYSTEM OF CO-ORDINATES, MEANS CONNECTING THE OUTPUT FROM SAID FILTER TO EACH OF SAID SAMPLING MEANS, SWITCHING MEANS COORDINATED RESPECTIVELY TO SAID SAMPLING MEANS FOR CONTROLLING THE OPERATING INSTANTS THEREOF, SAID SWITCHING MEANS BEING MOUNTED FOR ACTUATION IN SUCCESSION AT SAID SAMPLING POINTS BY ROTATION OF SAID SPINDLE MEANS, AND MEANS CONNECTED TO THE RESPECTIVE OUTPUTS OF SAID SAMPLING MEANS FOR INDICATING THE RESPECTIVE AMPLITUDES OF SAID FUNDAMENTAL COMPONENT AT SAID LOCATIONS OF SAID DIFFERENT SAMPLING POINTS DURING THE SAME REVOLUTION OF SAID FEELER IN WHICH SAID FUNDAMENTAL COMPONENT IS SEPARATED OUT FROM THE REMAINDER OF THE SIGNAL GENERATED BY SAID TRANSDUCER.