Robotics research and education have gained significant attention in recent years due to increased development and commercial deployment of industrial and service robots. A majority of researchers working on robot grasping and object manipulation tend to utilize commercially available robotmanipulators equipped with various end effectors for experimental studies. However, commercially available robotic grippers are often expensive and are not easy to modify for specific purposes. To extend the choice of robotic end effectors freely available to researchers and educators, we present an open-source lowcost three-finger robotic gripper platform for research and educational purposes. The 3-D design model of the gripper is presented and manufactured with a minimal number of 3-D-printed components and an off-the-shelf servo actuator. An underactuated finger and gear train mechanism, with an overall gripper assembly design, are described in detail, followed by illustrations and a discussion of the gripper grasping performance and possible gripper platform modifications. The presented open-source gripper platform computer-aided design model is released for downloading on the authors research lab website (www.alaris.kz) and can be utilized by robotics researchers and educators as a design platform to build their own robotic end effector solutions for research and educational purposes. INDEX TERMSOpen-source robotic gripper, gear train mechanism, 3D printing, underactuation, adaptive grasping. 638 2169-3536

In this paper authors present an open source lowcost basic robotic end effector platform for facilitating research on robotic grasping. The 3D design model of a three fingered underactuated robotic gripper is presented and manufactured with minimal number of 3D printed components and an off-theshelf servomotor actuator. An underactuated finger, gear train mechanisms and an overall gripper assembly design are described in details followed by illustration and discussion of grasping of objects with various geometries. The presented open source gripper design will be released for downloading on the authors' research lab web-site www.alaris.kz and can be useful for robotic researchers as a platform to build their own robotic end effector solutions for research and educational purposes.

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The connectivity of undersea sensors and airborne nodes across the water-air interface has been long sought. This study designs a free-space wireless laser communications system that yields a high net data rate of 850 Mbit/s when perfectly aligned. This system can also be used for an extended coverage of 1963 cm 2 at the receiver while sustaining a net data rate of 9 Mbit/s over 10 m. The utility of this system was verified for direct communications across the water-air interface in a canal of the Red Sea based on a pre-aligned link as well as a diving pool under a mobile signal-searching mode. The canal deployment measured a real-time data rate of 87 Mbit/s when pre-aligned in turbid water over 50 min, which confirms the system robustness in harsh water environments. In the pool deployment, a drone configured with a photodetector flew over the surface of the water and recorded the underwater signals without a structureassisted alignment. Using a four-quadrature amplitude-modulated orthogonal frequency-division multiplexing (4-QAM-OFDM) modulation scheme provided a net data rate of 44 Mbit/s over a 2.3-m underwater and 3.5-m air link. The results validated the link stability and mitigated problems that arise from misalignment and mobility in harsh environments, which paves the way for future field applications. INDEX TERMS Underwater communication, optical modulation, wireless communications, water-to-air communications, cross-medium communications, mobility I. INTRODUCTION The concept of the Internet of Underwater Things (IoUT) was proposed in 2012 to satisfy the demands of underwater communication networks [1]. The wide, license-free bandwidth and low energy consumption in such environments promote the consideration of underwater wireless optical communication (UWOC) as a transformative technology compared with conventional marine acoustic and radio-frequency (RF) technologies for high-speed communication activities in the IoUT. Verifications of the UWOC physical layer are progressing rapidly [2], with multiple Gbit/s-level UWOC links reported in laboratory studies [3]-[8]. Beyond investigations under ideal laboratory environments, researchers have considered the effects of various natural underwater processes on the performance of UWOC links. Bubbles [9], waves [10], aquatic life [11], water turbidity [12], and oceanic turbulence [13] all degrade communication performance in UWOC by altering the path of light propagation and by inducing misalignment.

This paper presents the design of a linkage based finger mechanism ensuring extended range of anthropomorphic gripping motions. The finger design is done using a path-point generation method based on geometrical dimensions and motion of a typical index human finger. Following the design description, and its kinematics analysis, the experimental evaluation of the finger gripping performance is presented using the finger 3D printed prototype. The finger underactuation is achieved by utilizing mechanical linkage system, consisting of two crossed four-bar linkage mechanisms. It is shown that the proposed finger design can be used to design a five-fingered anthropomorphic hand and has the potential for upper limb prostheses development.

<div class=""abs_img""> <img src=""[disp_template_path]/JRM/abst-image/00270005/05.jpg"" width=""300"" /> A robotic end effector prototype</div> Commercially available robotic grippers are often expensive and not easy to modify for specific purposes of robotics research and education. To extend the choice of robotic end effectors available to researchers, this paper presents the preliminary work on prototype design and analysis of a three-finger underactuated robotic end effector with a breakaway clutch mechanism suitable for research in robot manipulation of objects for industrial and service applications. Kinematic models of the finger and the breakaway clutch mechanisms are analyzed aiming to define selection criteria of design parameters. Grasping performance of the end effector prototype manufactured with a 3D printing technology and off-the-shelf components is evaluated using simulation and experimental analyses. Comparison with widely applied available robotic end effectors shows the potential advantages of the proposed end effector design. </span>

Resistive strain and bending sensors offer a versatile platform for sensing various physical parameters with relatively little effort and budget. The lightweight, robust and compact sensors are extensively used in manifold low-power applications. Recently, scribed and flexible laserinduced graphene sensors have shown potent capabilities for a variety of measurements, including flow, deflection, and force. Achieving a high sensitivity to various stimuli remains a challenge due to limited change in relative resistance. In this paper, we report a multifunctional LIG sensor with widely tunable properties and significantly enhanced electromechanical performance. A method of repeated laser writing is used to increase the porosity, the uniform carbonization degree and, most importantly, the sensitivity of the LIG sensors. A gauge factor of 91.2 is achieved after three-times laser writing at low power, which is an increase of 750% to one-time laser writing and 720% higher than the ones previously reported for LIG strain sensors. The increase is attributed to a more porous surface morphology that provides more overlapping area and displacement of the graphene layers. A homogeneous bidirectional response was obtained by scribing the electrodes on both faces of the substrate. Parylene C-coating is used to protect the LIG sensors from environmental effects. Coated sensors were packaged to a PCB assembly for easy integration into various applications. An example is a LIG bending sensor customized for velocity profile monitoring of Unmanned Aerial Vehicles in the outdoor environment.