Supporting data for “Investigation of Tunable Soft Robotic and Its Application".

Field: Engineering (Physical Sciences)

Although existing soft robot bodies have a certain degree of deformation ability due to the material softness, their shape transformation range is still limited. To amplify the advantage of soft robots in environmental compatibility, researchers have argued that soft robots need to have tunability in adjusting their body shape or regulating their stiffness when facing different working conditions. Developing soft robots that can drastically change shape to adapt to extreme environments and have a large range of stiffness variation remains a challenging goal for researchers. This thesis is devoted to the study and development of new and effective active shape morphing and stiffness modulation methods for soft robots.First, soft robots enable axial deformations (contraction and extension), which can also be regarded as artificial muscle are developed. A new type of artificial muscle named braided flat-tube artificial muscle (BFAM) is proposed. BFAMs are fabricated by braiding lay flat tube (LFT) into cotton threads with a specific weaving method. Because of the considerable mechanical performance, conformable structure, and craft-like appearance, BFAMs are suitable for applications in human-robot interactions.Secondly, inspired by the shape of the Möbius strip, a new active shape morphing technology for soft robots, namely, pneumatic torsion strip (PTS), is developed. The pneumatic torsion strip applies bending torque directly to the soft body without generating in-plane strain and without affecting stiffness. Compared with the common deformation methods based on strain mismatch, the pneumatic torsion strip shows obvious advantages in local bending manipulation and scalability. The geometric and elastic energy models of the PTS are established to describe its mechanical behavior. To demonstrate the excellent properties of PTS, a 2 kg deformable woven carpet woven with PTS is made that can curl like a plant tendril to perform various functions.Thirdly, a thermally driven active shape morphing method was studied for different application scenarios. Shape-memory alloys (SMAs) are common actuation materials for robotic applications. They need to be designed to specific shapes to disperse local strains due to their inherently scant deformation. However, there are few effective SMA shapes or configurations available for out-of-plane deformation (local bending or rotation). Here, a dedicated configuration or shape of SMA strips, called SMA torsion strips (STSs), is proposed. The STSs can generate considerable torque output over a wide range of angles to freely chosen body joints. Even micro-sized joints can be driven by the proposed STSs. Finally, exploration and experimental study of stiffness modulation of soft robotics is conducted. Jamming is a commonly used stiffness variation method for soft robots, which includes three basic types, including particle jamming, fiber jamming and layer jamming. Here, the hybridization of these three fundamental jamming types is investigated. Besides, the jamming transition of a dense granular suspension fluid from fluid (hydrodynamic interactions) to solid-like state (frictional contacts) is studied. A universal gripper based on this approach is developed. It exhibits excellent flexibility and gripping stability when gripping delicate samples such as plants and sponges, which cannot be achieved by conventional universal grippers based on particle jamming.