Enhanced adaptive controller applied to SMA wire control

Abstract

Besides the mainly verified or validated properties of the modeling approaches of the SMA focusing to the modeling of the different observed effects, all these SMA models lack the applicability in different engineering applications and in the control of the SMA since they don’t describe a general behaviour of any SMA type or shape; idealizing the material constants and thereby disallowing their application into different systems, and into different applications scenarios and also for modelbased control design purposes. However, if an SMA wire within a control loop is replaced by another SMA wire with new properties, or with an SMA plate, etc. those mathematical models may be in detail weak to perform the control task as they lack generalization properties from an engineering point of view, and weak in understanding this actuator material behavior as an I/O-system with structured behavior. Model-based control approaches may allow in combination with suitable design approaches the design and the realization of robust control algorithms and therefore the general usage of the SMA not only to be used as actuator but also for application where the shape memory effect should not be used i.e. the actuation where the inverse model can cancel the expected behaviour of the SMA, therefore it is an open research topic as far as no SMA generalized behavioural based model exit (Ghanem 2010). Non-Model-based control systems are limited to the usage of the SMA as actuators in applications and need tuning for its procedures any time the material physical characteristics are changed. As a result, non-model-based adaptive control approaches in the position control of the SMA is of vital importance to be studied.