Control with a Time Delay Estimation and Its Application to an SMA Actuator

J.S. Yoon, H.J. Lee, and J.J. Lee (Korea)


Time delay estimation, sliding mode control, time delay control, perturbation estimation, switching action, SMA actuator


We reviewed controllers with a time delay estimation in this paper. Time delay control (TDC) and sliding mode control (SMC) are well known robust control schemes. Basically, the TDC has the advantage of a time delay estimation from which we can easily estimate the total uncertainty of a system. In contrast, the TDC causes a stick-slip phenomenon in the case of a system with a friction. By the way, the SMC does not have a time delay estimation but instead it can estimate a system’s uncertainty through a switching action. However, it requires quantitative model information. In order to solve the difficulties of the TDC and the SMC, some control schemes combining the time delay estimation with the switching action, such as a time delay control with a switching action (TDCSA), a sliding mode control with a perturbation estimation (SMCPE) and a sliding mode control with a time delay estimation (SMCTE), were proposed as a remedy. Even though the motives for the development of three control schemes are different, the three control schemes have much in common in terms of their controller structures. Among the three controllers, our proposed SMCTE was applied to an SMA actuator. Thereafter, it was proven that the SMCTE has a predominance in a comparison with other general control schemes such as the PID control and the relay control.

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