Technical note: On the actuator rate limit effect in reaction curves

While actuator rate limit is common and counted in practical engineering, it has not drawn enough attention in control synthesis especially system identification. In this note, it aims to construct a new identification framework for first-order plus time-delay (FOPTD) systems affected by actuator rate limit. It is found that the rate limit can lead to an illusory delay in system reaction curves. Furthermore, necessary quantitative analyses are given to validate that excessively estimated or illusory delay significantly influences estimation accuracy of other parameters and subsequently degrades control performance. Two illustrative examples and experimental results are provided to demonstrate the adverse effect of actuator rate limit on system identification and the effectiveness of the proposed model structure on control performance.