Method and apparatus for locating a movable servo controlled member during position signal drop-out
AssigneeSperry Corporation
InventorsAndrew M. Rose, Frank J. Sordello, James J. Touchton
Life of this patent
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Abstract
As an aid in counting servo tracks in a position servo system, a position window detector (30) which normally provides coarse and fine pulses to counting logic (53) also provides fine pulses to a reset switch (45) of a tachometer signal integrator means (33), resetting the integrator once for each track. In the event of position signal drop-out wherein coarse pulses are not properly generated, a threshold detection means (43) senses when the output of the integrator reaches a threshold level and produces a threshold reached signal which is transmitted to counting logic means (53) for incrementing a track counter (61).
Claims16
In a position servo system of the type having a member movable longitudinally and transversely with respect to a plurality of servo tracks in which member position and velocity transverse to said tracks is represented by position and velocity signals, the system having a track counter to be decremented by the member crossing each track, a circuit for use in track counting in the event of position signal drop-out comprising,
- integrator means having an input and an output, said input connected to receive and integrate a velocity signal to produce a simulated position signal, said integrator means having a reset switch operable in response to a reset command,
- window circuit means, connected to said reset switch, for generating coarse and fine cylinder signals for a servo track, a fine cylinder signal being directed to said reset switch as a reset command for said integrator means so that a simulated position signal is generated by said integrator means for each servo track,
- detector means connected to the output of said integrator means for generating a threshold reached signal representing the passage of said simulated position signal past a preset threshold level corresponding to a characteristic of each servo track, and
- counting logic means for decrementing a track counter, said counting logic means connected to said threshold detection means and operable in response to said threshold reached signal.
In a position servo system of the type having a member movable longitudinally and transversely with respect to a plurality of servo tracks, in which member position and velocity transverse to said tracks is represented by position and velocity signals, the system having a track counter to be decremented by the member crossing each track, a circuit for use in track counting in the event of position signal drop-out comprising,
- integrator means having an input and an output, said input connected to receive and integrate a velocity signal to produce a simulated position signal, said integrator means having a reset switch operable in response to a reset command,
- a first detector means connected to the output of said first integrator means for generating a first threshold signal representing the passage of the simulated position signal from said integrator means past a preset threshold level corresponding to a first characteristic of a servo track, said first threshold signal communicating a first command to a counting logic means,
- a second detector means connected to the output of said integrator means for generating a second threshold signal representing the passage of the simulated position signal from said integrator means past a preset threshold corresponding to a second characteristic of a servo track, said second threshold signal communicating a reset command to the reset switch of said integrator means and communicating a second command to the counting logic means, and
- counting logic means connected to said first and second detector means for decrementing a track counter in response to said first and second commands.
For counting servo tracks crossed by a movable member in a position servo loop, wherein the movable member has a velocity signal and a position signal partially subject to drop-out, the method comprising,
- electrically integrating a movable member velocity signal to form a simulated position signal,
- resetting the integrated velocity signal by an integrator reset signal for each servo track to form a simulated position signal for each servo track,
- detecting the passage of the simulated position signal past a threshold corresponding to a track position, and
- decrementing a counter each time a threshold passage is detected.
Dependencies are inferred from the claim text.