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.

No abstract

No abstract

Recent achievements in active capsule endoscopy have allowed controlled inspection of the bowel by magnetic guidance. Capsule localization represents an important enabling technology for such kinds of platforms. In this paper, the authors present a localization method, applied as first step in time-discrete capsule position detection, that is useful for establishing a magnetic link at the beginning of an endoscopic procedure or for re-linking the capsule in the case of loss due to locomotion. The novelty of this approach consists in using magnetic sensors on board the capsule whose output is combined with pre-calculated magnetic field analytical model solutions. A magnetic field triangulation algorithm is used for obtaining the position of the capsule inside the gastrointestinal tract. Experimental validation has demonstrated that the proposed procedure is stable, accurate and has a wide localization range in a volume of about 18 × 10 3 cm 3. Position errors of 14 mm along the X direction, 11 mm along the Y direction and 19 mm along the Z direction were obtained in less than 27 s of elaboration time. The proposed approach, being compatible with magnetic fields used for locomotion, can be easily extended to other platforms for active capsule endoscopy.

No 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.

Tactile sensing transfers complex interactive information in a most intuitive sense. Such a populated set of data from the environment and human interactions necessitates various degrees of information from both modular and distributed areas. A sensor design that could provide such types of feedback becomes challenging when the target component has a nonuniform, agile, high resolution, and soft surface. This paper presents an innovative methodology for the manufacture of novel soft sensors that have a high resolution sensing array due to the sensitivity of ceramic piezoelectric (PZT) elements, while uncommonly matched with the high stretchability of the soft substrate and electrode design. Further, they have a low profile and their transfer function is easy to tune by changing the material and thickness of the soft substrate in which the PZTs are embedded. In this manuscript, we present experimental results of the soft sensor prototypes: PZTs arranged in a four by two array form, measuring 1.5-2.3 mm in thickness, with the sensitivity in the range of 0.07-0.12 of the normalized signal change per unit force. We have conducted extensive tests under dynamic loading conditions that include impact, step and cyclic. The presented prototype's mechanical and functional capacities are promising for applications in biomedical systems where soft, wearable and high precision sensors are needed.

No abstract