Intelligent robotic systems that can react to unprogrammed tasks and unforeseen environmental changes require augmented “softness.” Robogami, a low-profile origami robot, addresses intrinsic (material-wise) and extrinsic (mechanism-wise) softness with its multi-degree-of-freedom (DOF) body driven by soft actuators. The unique hardware of the Robogami and its submillimeter thick construction enable diverse transformations as those achievable by the paper origami. The presented Robogami shows the first fully integrated version that has all the essential components including its controller within a thin sheet. Construction of this robot is possible via precise, repeatable, and low cost planar fabrication methods often reserved for microscale fabrications. In this research, we aim at expanding the capabilities of Robogamis by embedding bidirectional actuation, sensing, and control circuit. To assess the performance of the proposed sensors and actuators, we report on the performance of these components in a single module and in the four-legged crawler robot.

Abstract-Under-actuated systems offer compact designs with easy actuation and control but at the cost of limited stable configurations and reduced dexterity compared to the directly driven and fully actuated systems. Here, we propose a compact origami-based design to control the stable configurations and the overall stiffness of an under-actuated robotic finger by modulating the material stiffness of the joint. The design of the robotic finger is based on the robotic origami design principle in which multiple functional layers are integrated to make a nominally 2D robot with a desired functionality. To control the stiffness of the structure, we controlled the elastic modulus of a shape memory polymer (SMP) via embedded customized stretchable heater. We monitor the configuration of the finger using the feedback from the customized curvature sensors embedded in each joint. We studied the stable configurations and the contact forces of a finger with 3 joints at different stiffness settings. A scaled down version of the design was used in a gripper with two fingers and different grasp modes were demonstrated through activating different set of joints.

Every robotic gripper requires an equilibrated solution towards the grasp adaptability, precision, and load bearing capacity. A versatile soft robotic gripper requires adjustable grasp mode, for objects with different sizes and shapes, and adjustable compliance, for switching between soft mode; for small loads and delicate objects; and stiff mode; for larger loads and heavier objects. In this paper, we present the design of a tendon-driven robotic origami, robogami, gripper that provides self-adaptability and inherent softness through its redundant and under-actuated degrees of freedom (DoF). Robogami is a planar and foldable robotic platform that is scalable and customizable thanks to its unique layer-by-layer manufacturing process. The nominally 2D fabrication process allows embedding different functional layers with a high fidelity. In particular, a polymer layer with adjustable stiffness enables the independent control of the stiffness for each joint. Using this feature, we can control the input energy distribution between different joints and hence the motion of the robogami. Here, we model the behavior of a single finger; and demonstrate the compliance control of the endeffector along different directions in simulations and experiments. We also validate the gripper's task versatility in soft and stiff modes by assigning model-based joints stiffness for performing different grasp modes.

b) Figure 1. Examples of different shapes a Robogami can transform into (a) a table (b) a pinwheel. Abstract-The robotic origami (Robogami) is a low-profile, sheet-like robot with multi degrees-of-freedom (DoF) that embeds different functional layers. Due to its planar form, it can take advantage of precise 2D fabrication methods usually reserved for micro and nano systems. Not only can these methods reduce fabrication time and expenses, by offering a high precision, they enable us to integrate actuators, sensors and electronic components into a thin sheet. In this research, we study sensors, actuators and fabrication methods for Robogami which can reconfigure into various forms. Our main objective is to develop technologies that can be easily applied to Robogamis consisting of many active folds and DoFs. In this paper, after studying the performance of the proposed sensors and actuators in one fold, we use a design for a crawler robot consisting of four folds to assess the performance of these technologies.

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.

a b s t r a c tRecent robots target safety, reconfigurability and interactivity by addressing the "softness" of the hardware either by endowing additional degrees-of-freedom or through inherent compliancy. These robots require distributed sensing with flexibility and softness that would not interfere with the robot's agility. There have been various sensing solutions using soft conductive materials including conductive silicone, liquid metal-filled micro-channels, and conductive-ink based sensors. However, we still lack a comprehensive study on their potentials, drawbacks, and the different parameters that affect their response.We present our design, fabrication process and characterization results for conductive silicone polymer and carbon ink-based curvature sensors. These sensors are flexible, mechanically robust under large strains, scalable, and easy to fabricate in large numbers. We propose an equivalent mechanical system to model sensors' response. This model is unique for its extensive characterization of these polymer based sensors. Based on the characterization results, we systematically categorize and compare the performance of conductive silicone and carbon ink-based sensors with different design parameters.

Under-actuated robots offer multiple degrees of freedom without much added complexity to the actuation and control. Utilizing adjustable stiffness joints in these robots allows us to control their stable configurations and their mode of interaction with the environment. In this paper, we present the design of tendon-driven robotic origami (robogami) joints with adjustable stiffness. The proposed designs allow us to place joints along any direction in the plane of the robot and in the normal direction to the plane. The layer-by-layer manufacturing of robogamis facilitates the design and manufacturing of robots with different arrangement of joints for different applications. We use thermally activated shape memory polymer to control the joint stiffness. The manufacturing of the polymer layer is compatible with the layer-by-layer manufacturing process of the robogamis which results in scalable and customizable robots. To demonstrate, we prototyped an under-actuated gripper with three fingers and only one input actuation. The grasp mode of the gripper is set by adjusting the configuration of the locked joints and modulating the stiffness of the active joints. We present a model to estimate the configuration and the contact forces of the gripper at different settings that will assist us in design and control of future generation of under-actuated robogamis.

In this paper application of ionic polymer–metal composite (IPMC) as an actuator in a deformable circular robot is studied. Large bending deformation induced by small stimulating voltage, low stiffness and the sensing characteristics that in future work can be used in feedback control make IPMC a good choice for such an application. Here, first a model for IPMC is proposed that can be used in simulating different arrangements of actuators. The parameters of the model are determined using results of blocked force and free displacement tests. Using this model, potentials of an IPMC-made ring-like robot in passing obstacles and the effect of the number of segments on the ring’s performance are investigated. Next, the result of an experiment on a ring made of six segments is presented and the applicability of the proposed design is confirmed. In future, by modifying the fabrication process and implementing more elaborate control schemes, faster and steadier movement can be achieved.