Multi-channel soft robotic films for actively bendable electronics and undulation-based-locomotion

Abstract

The ability to actively control mechanical softness offers promising new possibilities for conventional devices such as flexible electronics and soft robotics. Flexible electronics enable foldable, rollable, stretchable, and wearable devices, and soft robotics enable soft grippers, soft surgical robots, and soft locomotive robots. While flexible electronics offer the functionalities of existing electronic devices, soft robotics have the advantage of adding mobility to soft materials. By combining these two properties, actively deformable soft electronics such as self-deformable displays or self-deformable photovoltaics can be realized. The main focus of this dissertation was to develop design and control strategies to combine present flexible electronics with soft robotic actuators. To accomplish that, three main characteristics are required. First, we need thin film configurations, to minimize the mechanical strain in film type electronics. Secondly, an electrical actuating stimulus is required that is suitable for actuating conditions, and uses integrated electronics without additional components. Finally, diverse actuating motions should be possible, to maximize the advantages of actively deformable electronics. This dissertation proposes thin film type soft robotic actuators based on electrically driven smart materials which can deform in various shapes based on their structural design and multi-channel configuration. Two kinds of materials, shape memory alloy (SMA) wires and dielectric elastomer actuators (DEAs), are used. Based on the contractile SMA wires, self-bendable soft robotic films were fabricated using a micro-fabrication process. Various design parameters enabled the film type actuators to achieve multiple shapes, and reversible bending and unbending motions were possible. The thin film configuration was stably integrated with current flexible LED arrays, to demonstrate actively deformable electronics. Also, SMA wires and DEA based multi-channel soft robotic films were fabricated, which enabled a partially actuatable film using the proposed multi-channel configurations of each actuator. More various reconfigurable shapes can be achieved by using localized control regions. A reconfigurable display, self-rollable display, and self-rollable photovoltaics were realized to prove the feasibility of the concept. Lastly, multi-channel SMA wire-based crawling soft robots were fabricated, with forward and backward locomotion using the self-sensing characteristics of SMA wires and reinforcement learning based control. The localized feedback control of a multi-channel soft robotic film was demonstrated, and functional locomotion was realized by converging flexible electronics.