Design and development of butterfly configuration aerial robots

Abstract

Micro-aerial robots can play a significant role in the defense forces’ surveillance and monitoring activities. Unlike conventional robots, soft robots are composites of flexible materials that safely interact with human operators and function in unstructured environments. Shape Memory Alloy (SMA) have a very high energy density and are usable in various shapes, including rods, plates and wires. One of the significant limitations of SMA based soft actuators is the low actuation frequency. The main reason for lower actuation frequency is the slow cooling of SMA wires which is controlled by the surface area available for convective cooling. Initially, the focus is on fabricating the structure of PDMS integrated with the SMA wires using a mold. A mold with a cuboidal slit of dimension 100 mm X 20 mm X 1 mm is designed with the PLA material using a 3-D printer. Now the SMA wires are integrated in this mold in the desired orientation using screws and nuts. Thereby, the PDMS is cured with a curant by mixing these components in 10:1 ratio. The cured mixture is then poured in the mold and heated in the furnace at 50℃ for around 6-8 hours. Investigation on the effect of process parameters like the diameter of the SMA wire as well as the strain percentage of the wires is also a matter of concern. Succeeding this, combinations of SMA wires of 100 µm and 250 µm by straining them from 1-8% are used. And finally, the material characteristics as well as the actuation characteristics for all these combinations of actuators are noted. Despite giving reasonable results, this actuator doesn’t meet the expectations regarding high frequency. Hence, the next objective is to try and enhance the actuator by embedding a ply and having SMA wires on either side. This would facilitate higher frequencies and help in bending of the actuator on either side. We carry the same experiment that we have done above for the fabrication of the actuator. The only addition to it is an insertion of ply and also another set of SMA wires using the support of position guides. Finally, we will be observing the actuation of this new Smart Soft Composite (SSC) and then and then implement it using a prototype whose design will be elaborated in the further parts.