Soft pneumatic actuator with adjustable stiffness layers for Multi-DoF Actuation

Abstract

Abstract-The soft pneumatic actuators (SPAs) are a solution toward the highly customizable and light actuators with the versatility of actuation modes, and an inherent compliance. Such flexibility allows SPAs to be considered as alternative actuators for wearable rehabilitative devices and search and rescue robots. In applications that require a high compliance for safety and a fluid interactivity, the SPAs material-based softness returns an inherent back-drivability. One of the main challenges that limits the wide application of SPAs is in the complexity of miniaturizing the actuators and embedding additional degree of freedoms (DoFs) in a single actuator. We present a novel design and fabrication method of a SPA with different modes of actuation using adjustable stiffness layers (ASLs). Unlike conventional SPA designs where one independent chamber is needed for each mode of actuation, here we have a single chamber that drives three different modes of actuation by activating different combinations of ASLs. By using customized micro heaters and thermistors for controlling the temperature and stiffness of ASLs in increments, we considerably broaden the work space of the SPA actuator. Here, a thorough characterization of the materials and the modeling of the actuator are presented. In the conclusion, we propose a design methodology for developing application specific actuators with multi-DoFs that are light and compact.

Automatic design of fiber-reinforced soft actuators for trajectory matching

“…axial extension, radial expansion, and twisting about its axis upon pressurization (17)(18)(19). In contrast, when the tube is composed of two elastomers of different stiffness, pressurization produces a bending motion (25,26).…”

Stiffness Control With Shape Memory Polymer in Underactuated Robotic Origamis

“…The holes in the SMP layer presented in Fig. 3b will shape silicone columns that would transfer the force between the silicone and the SMP (the design details are in [22]). …”

“…Compared to the designs that are based on motors and mechanisms, using material properties results in a more compact and scalable design. The glass transition in thermoplastics [18]- [22], Jamming [23]- [25], and phase change of wax [26] and metals [27], [28] are among the different methods [29] that use material properties for controlling the stiffness of the structure.…”

Practical control methods for vacuum driven soft actuator modules

“…While the initial task of soft robotics research was to develop new methods of performing work and force output using both smart materials and pneumatic pressure, subsequent effort has begun to focus on the control of systems powered by these new soft technologies. Both efforts are still very present and ongoing, with a large variety of Soft Pneumatic Actuators (SPAs) to be found representing the diversity and scope of interest in the domain [1]- [6]. While the cornerstone of research in soft robotics will always focus to some extent on developing new core technologies, as new fabrication process are developed [7], [8], new materials are engineered [8], [9], and different applications become the target of compliant robotics [10]- [12], a wider, system-level view of design is becoming increasingly necessary in order to facilitate the control and integration more complex multi-DoF soft robots.…”