Credibility testing in sampled-data systems

Claim 1

A closed-loop speed control servomechanism operable to variably energize a motor in a start-run-stop sequence to achieve a desired acceleration, constant speed run and deceleration profile, comprising: digital tachometer means driven by said motor and operable to provide sampled-data period feedback data in accordance with actual motor speed, said feedback data being aperiodic during acceleration and deceleration, and being substantially periodic during constant speed run, speed memory means containing desired period data and permissible period window data which define the motor''s desired acceleration, constant speed run and deceleration profiles, means providing motor start and stop commands, means including clock means connecting said motor start and stop commands in controlling relation to said memory means to periodically interrogate said memory means, period testing network means receiving as inputs said period feedback, said desired period data and permissible period window data, and operating thereon to test said feedback data against a permissible period window data to determine if said feedback data is valid or invalid, hold network means controlled by said testing network means when said feedback data is valid and operable to hold said valid feedback data, and means including said hold network means operable to selectively supply current valid feedback data or to substitute therefor feedback data which is a function of prior valid feedback data for use by said servomechanism, in accordance with said current feedback data passing or failing said test, respectively.