Comparison of open and closed loop process identification techniques in the time domain

This paper describes seven methods to identify a mathematical model for a real process with a time delay. The process is the Process Trainer, PT326 from Feedback Instruments Limited. Six of the methods use the step response data and one of the methods uses the impulse response data for identification. Introduction: The dynamics of a process can be determined from the response of the process to pulses, steps, ramps, or other deterministic signals. The dynamics of a linear system are, in principle, uniquely given from such a transient response experiment. Such experiments require that the system be at rest before the input is applied. Models obtained from a transient experiment are sufficient for PID controller tuning. The methods are implemented using the following tools: • MatLab Version 5.3 • Simulink, Simulink Version 3 Library • Humusoft Real Time Toolbox Version 3.0 • AD512 Data Acquisition Card plugged into ISA port • Process Trainer PT326 • 37-pin D-type connector, 37-way cable and connector block