Development of a Novel 3-Universal-Spherical-Revolote Soft Parallel Robot

Abstract Soft parallel robots are among the latest advancements in the field of soft robotics with wide range of applications. Most of the existing soft robotic systems comprise from serial soft arms which can provide high degrees of freedom (DOF), but suffer from low stiffness, and limited payload due to their soft structure. To address these issues recently researchers have introduced soft parallel robots. Similar to their rigid counterparts, soft parallel robot will have higher blocking force, stiffness, and accuracy. We have previously introduced two, and three DOF soft parallel robots and in the current work we will introduce a novel six DOF robot named 3-universal-spherical-revolute (3USR) soft parallel robot. This robotic system is consisted of three closed-loop kinematic chains. Each chain includes a soft active arm with two DOF which is connected to a compliant passive link through soft joints. This configuration provides six DOF for the soft robot (x, y, z, roll, pitch, yaw). The prototype of the robot is 3D printed using NINJA flex, thermoplastic polyurethane (TPU), and polylactic acid (PLA). Each soft active arm consists of a two DOF tendon driven soft actuator which is 3D printed using NINJA flex and are actuated using two servo motors. Two types of soft joints are used namely soft spherical and revolute joints. The shape and size of the soft joints are optimized so that the robot will achieve six DOF. MATLAB Simscape model is used to simulate the dynamical response of the mechanism for various inputs.