Development of a redundant anthropomorphic hydraulically actuated manipulator with a roll-pitch-yaw spherical wrist

Abstract

The demand for redundant hydraulic manipulators that can implement complex heavy-duty tasks in unstructured areas is increasing; however, current manipulator layouts that remarkably differ from human arms make intuitive kinematic operation challenging to achieve. This study proposes a seven-degree-of-freedom (7-DOF) redundant anthropomorphic hydraulically actuated manipulator with a novel roll-pitch-yaw spherical wrist. A hybrid series-parallel mechanism is presented to achieve the spherical wrist design, which consists of two parallel linear hydraulic cylinders to drive the yaw/pitch 2-DOF wrist plate connected serially to the roll structure. Designed as a 1RPRRR-1SPU mechanism (“R”, “P”, “S”, and “U” denote revolute, prismatic, spherical, and universal joints, respectively; the underlined letter indicates the active joint), the 2-DOF parallel structure is partially decoupled to obtain simple forward/inverse kinematic solutions in which a closed-loop subchain “RPRR” is included. The 7-DOF manipulator is then designed, and its third joint axis goes through the spherical center to obtain closed-form inverse kinematic computation. The analytical inverse kinematic solution is drawn by constructing self-motion manifolds. Finally, a physical prototype is developed, and the kinematic analysis is validated via numerical simulation and test results.

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Bibliometric analysis and visualization of research and development trends in humanoid robotics

“…Traditional rigid robotic arms [23] are heavy, expensive, inefficient, and even potentially dangerous, and researchers are favoring lightweight, flexible, flexibly linked robotic arms with soft joints or flexible parts that mimic living organisms [24][25]. Furthermore, in order to improve obstacle avoidance and self-adaptive capabilities, identify and place targets, and enable closed-loop control of the robotic arm to carry out the precise operation, redundant robotic arms [26] and machine vision technologies are introduced [27].…”

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