Robust Deadtime Compensation for Nonlinear Processes

Many industrially important processes are nonlinear and also have a process deadtime. Powerful deadtime compensation methods, such as the Smith predictor, are available for linear systems. Additionaly, recent work has shown that state feedback, such as in the Globally Linearizing Control structure, can provide linear input/output behavior for delay-free nonlinear systems. A combination of these two approaches is proposed. A state feedback is found for general SISO systems which makes the nonlinear process with deadtime behave like a linear process with deadtime. An external Smith predictor is then used to compensate for the deadtime of this linear system. Computer simulations for an example system demonstrate the high controller performance that can be obtained using the proposed method.