“…Different control laws and methods have been implemented to address this issue in rotary actuators. For example, a differential resistance feedback sensorless technique was proposed in the work by (Ruth et al (2012, 2015) to create a bi-directional angular control system. SMA wires were not only used as driven elements, but also as sensors.…”
International audienceThe development of rotary actuators is an important issue of the engineering applications of shape memory alloys (SMAs). This paper reviews about a hundred references on this topic, and presents around eighty actuators driven by SMAs. A classification is made according to the type of rotation (continuous or non-continuous), the single or reversible direction of the rotation, as well as the number of SMA elements involved in the device. Different issues are then discussed, such as the characteristics of the SMA elements, the heating and cooling system for the SMA, the control of the actuator, as well as the output torque and stroke which can be reached. This paper provides the first review focused on rotary actuators triggered by SMAs, highlighting the specificities and potentialities of such actuators for new applications in the future
“…Different control laws and methods have been implemented to address this issue in rotary actuators. For example, a differential resistance feedback sensorless technique was proposed in the work by (Ruth et al (2012, 2015) to create a bi-directional angular control system. SMA wires were not only used as driven elements, but also as sensors.…”
International audienceThe development of rotary actuators is an important issue of the engineering applications of shape memory alloys (SMAs). This paper reviews about a hundred references on this topic, and presents around eighty actuators driven by SMAs. A classification is made according to the type of rotation (continuous or non-continuous), the single or reversible direction of the rotation, as well as the number of SMA elements involved in the device. Different issues are then discussed, such as the characteristics of the SMA elements, the heating and cooling system for the SMA, the control of the actuator, as well as the output torque and stroke which can be reached. This paper provides the first review focused on rotary actuators triggered by SMAs, highlighting the specificities and potentialities of such actuators for new applications in the future
“…For SMA in other forms such as bending sheets or torsional springs, the image processing is often implemented, and it is proven to be a suitable method for motion sensing (see Table 2). Beyond this two common methods, one needs to highlight two approaches on sensing of SMA for BRM: 1) SMA wires can be used as self-sensing actuators because its unique hysteresis: the variation of its electric resistance R and the strain of actuator ϵ yield a linear relation due to the changing of its geometry (Ruth et al, 2015;Prechtl et al, 2020); 2) A stretchable mesoscale bending sensor named "elastic curvature sensor" is presented in (Firouzeh et al, 2013), it is manufactured using carbon impregnated silicone rubber and it is capable of offering a repeatable measurement with a rotation angle up to 150°.…”
Section: Sensing and Controlling Methodsmentioning
confidence: 99%
“…Based on this approach, Moghadam et al (2019) showed that the introduction of BM and a cascade control offers better accuracy than the former. Ruth et al (2015) proposed a self-sensing actuator using electrical resistance measurement, and the prototype showed a result of a 30°s troke with a 2°error. For the third improvement, the work of Doroudchi et al (2018) used forced air convection to accelerate the cooling time, resulting in 5 Hz with a 4°stroke and 10 Hz with a 1°stroke.…”
Section: Linear Shape Memory Alloy Element With Mechanical Jointmentioning
confidence: 99%
“…One needs to remind that for a certain case like thin linear SMAs wires, the variation of electrical resistance of actuator can show a nonlinear behavior due to phase transition and shapechanging (Ruth et al, 2015). Such investigation is presented in Velázquez et al (2006), in which he developed a temperature and deformation-based function of electrical resistance, resulting in improvement of modeling precision.…”
Shape memory alloys (SMAs) are a group of metallic alloys capable of sustaining large inelastic strains that can be recovered when subjected to a specific process between two distinct phases. Regarding their unique and outstanding properties, SMAs have drawn considerable attention in various domains and recently became appropriate candidates for origami robots, that require bi-directional rotational motion actuation with limited operational space. However, longitudinal motion-driven actuators are frequently investigated and commonly mentioned, whereas studies in SMA-based rotational motion actuation is still very limited in the literature. This work provides a review of different research efforts related to SMA-based actuators for bi-directional rotational motion (BRM), thus provides a survey and classification of current approaches and design tools that can be applied to origami robots in order to achieve shape-changing. For this purpose, analytical tools for description of actuator behaviour are presented, followed by characterisation and performance prediction. Afterward, the actuators’ design methods, sensing, and controlling strategies are discussed. Finally, open challenges are discussed.
“…To further understand the superelastic effect in an SMA helical spring, it is very important to study the mechanical properties of an SMA helical spring under complex loading and unloading conditions. In addition, motivated by the fact that an SMA device can also be used as a sensor by monitoring its electric resistance or inductance change [24,25,26,27,28,29,30], one can develop the self-sensing functions of SMA springs to measure the displacements or forces of springs under a seismic load. These self-sensing functions are also very significant for understanding the mechanical properties of SMA springs subjected to complex loading.…”
This paper proposes a new force-displacement model for superelastic shape memory alloy (SMA) springs under complex loading and unloading. For the SMA wires used to make superelastic springs, a new multilinear constitutive model based on a modification of the 1D Motahari model is developed. In the modified model, the stress-strain relation curves are changed to fit the experimental results. Furthermore, the established force-displacement relationship of the springs considers the impact of not only the torque but also the moment on the cross sections of the SMA wires. Afterwards, a series of tension tests are performed on four NiTi helical spring specimens under various loading conditions. From the numerical simulations and experimental results, it is shown that, compared with the force-displacement curves for the SMA springs simulated by the Motahari model, those simulated by the proposed model can better approximate the experimental results. The new model inherits the advantage of simple computation of the multilinear constitutive model and can predict the force-displacement relation for superelastic SMA springs very well. Furthermore, due to the self-sensing properties of the SMA springs, the new model is very significant for establishing a new strategy for measuring the displacements or forces of SMA springs under complex loading and unloading.
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