Industrial process control apparatus and method

In apparatus for the operational control of a non-linear process having a control member determining that operation in response to an input desired operation parameter, the combination of

• first means for providing feedback control of said control member in accordance with said desired operation parameter,
• second means for sensing a monotonic external disturbance tending to either increase or decrease said process operation level,
• third means for providing a feed-forward first control signal in accordance with said external disturbance,
• fourth means responsive to and modifying said first control signal in accordance with a predetermined absolute lead/lag characteristic such that, when said external disturbance tending to increase said process operation level occurs, a first positive signal component is added to said first control signal, which component is maintained until after that disturbance ceases and is then allowed to gracefully decay once said process operation level approaches steady state, and, when said external disturbance tending to decrease said process operation level occurs, a second positive signal component is added to said first control signal, which component is maintained until after that disturbance ceases and is then allowed to gracefully decay once said process operation level approaches steady state, said fourth means providing a second control signal so modified,
• with said first means being responsive to the provision of said second control signal for determining the operation of the control member.