Frequency-domain control design for shape memory alloy actuators

Characterization and design of antagonistic shape memory alloy actuators

“…Since SMA active elements are thin wires, and they are activated by direct Joule heating, the use of strain sensors mounted directly on SMA active elements is problematic. To adequately address this issue, the displacement is measured using the encoders (10) installed on the DC motors (11). The temperature of the specimen is measured by a thermocouple (TT-K-36-SLE, Omega Engineering Inc., CT) electrically isolated from the specimen with a heat sink compound and fixed to the specimen using PTFE ribbon.…”

“…Other advantages offered by SMA actuators are their silent and smooth motion and autosensing ability. The main drawbacks of SMA actuators are their relatively low actuation frequency (several Hertz) and the challenges inherent in establishing good practices to control their actuation stability [9,10]. This is especially true for antagonistic SMA actuators, which have received relatively little attention in the literature until now, and which therefore represent the main subject of this work.…”

The Dynamic Modeling of a Shape Memory Alloy

“…These advantages can simplify the actuator structure and reduce the costs. Many scholars made plentiful research on SMA actuator, such as F. Schiedesk [2], D. Js [3] and Dong Erbao [4]. The research direction mainly focuses on SMA modeling, control method and response frequency.…”

“…There are many factors that affect the dynamic performance of SMA wire actuator, such as the geometric size, the phase transition temperature (Mf, Ms, As Af) [1], the electric heating method, the mechanical load and the ambient temperature [5] and so on. In the field of engineering applications, these factors make the SMA actuator mechanism modeling [2,6,7] process complicated.…”

“…Based on the input-output model identification method [3], The system identification toolbox of MATLAB is used to obtain the model which can meet the requirements and is easy to use. There are Hammerstein-Wiener model [2], Process model [8] and ARX model [9] and so on in the system identification toolbox. Compared with the mechanism model, the identification model can not reflect the mechanism of SMA, but it can correctly reflect the corresponding relationship between the physical quantity of SMA, and its flexibility makes the engineering application of SMA easy.…”