Method of measuring the instantaneous shaft velocity of a rotary machine

An apparatus for measuring the instantaneous shaft velocity of a rotary machine having a shaft with plurality means thereon defining circumferentially spaced markers, comprising:

• at least two circumferentially spaced sensors for mounting adjacent the shaft to sense the passage of said markers and generate a stream of pulses in response thereto;
• for each of said sensors, a processing channel comprising a conditioner for conditioning said pulses, a counter for measuring the time intervals between said pulses, a memory for storing a set of measured time intervals (.DELTA.T.sub.1,2), an address generator for specifying the location of said set of stored measured time intervals in said memory, and an output register for outputting the stored set of measured time intervals (.DELTA.T.sub.1,2);
• a data bus connected to said output register of each said processing channel;
• and
• a central processor connected to said data bus for generating signals representing a set of estimated spacings of said successive markers and associating said estimated spacings with corresponding stored measured time intervals, said central processor further deriving for each pair of corresponding timing and spacing signals a signal representing the instantaneous angular shaft velocity, and said central processor varying the signals representing the estimated spacings of said markers on an iterative basis to attempt to make the angular velocity signals derived from the respective sensors the same;
• and
• output means for generating a waveform representing the instaneous shaft angular velocity from said angular velocity signals derived from the respective sensors.

A method of measuring the instantaneous shaft velocity of a rotary machine having a shaft with a plurality of means thereon defining circumferentially spaced markers, comprising:

• sensing the passageway of said markers with at least two circumferentially spaced sensors mounted adjacent the shaft to generate a stream of pulses in response to the passage of said markers thereby;
• for each of said sensors, continually generating timing signals representing a set of timing measurements corresponding to the passage of n successive markers thereby, storing said timing signals in a memory, and generating signals representing a set of estimated spacings for said n respective successive markers, for each pair of corresponding timing and spacing signals deriving a signal representing the instantaneous angular shaft velocity;
• varying the signals representing the estimated spacings of said markers on an iterative basis to attempt to make the angular velocity signals derived from the respective sensors the same;
• and
• generating from said angular velocity signals derived from the respective sensors an output waveform corresponding to the instantaneous shaft angular velocity.