Method and apparatus for adaptive deadtime process control

A proportional-integral-derivative deadtime process controller for measuring a controlled variable signal representative of a first characteristic of a process, and for applying a manipulated variable signal to that process to vary that first characteristic, said controller comprising

• A. proportional derivative means for generating an PD signal indicative of an error in said controlled variable signal, said proportional derivative means including means for generating said PD signal as a function of a time rate of change of said controlled variable signal and a difference between said controlled variable signal and a predetermined setpoint,
• B. summation means, coupled with said proportional derivative means, for summing said PD signal and a time-delayed integral signal to generate a summation signal,
• C. noise filter means, coupled with said summation means, for filtering said summation signal to generate a manipulated variable signal, said noise filter means having a filter time constant .tau..sub.f,
• D. controlled variable signal output means for selectively applying said manipulated variable signal to said process, and
• E. feedback means, coupled to said controlled variable signal output means, for processing said manipulated variable signal to generate said time-delayed integral signal, said processing including
• i) time-delaying said manipulated variable signal an amount substantially equal to a deadtime, .tau..sub.d, and
• ii) passing that time-delayed manipulated variable signal through a first-order lag of time constant I to generate said time-delayed integral signal.