Manipulator with multiple operation modes using fluid power transmission

Abstract This study introduces a reconfigurable mechanism that employs fluid power transmission. By leveraging the unique characteristics of fluid power, the mechanism enables switching between operation modes through valve operations. Although concerns exist regarding the strength and wear of specialized joints and locking mechanisms commonly found in reconfigurable mechanisms, the proposed fluid-based mechanism can be constructed entirely from standard industrial components. Moreover, the fluid circuit is designed to allow mode switching in any kinematic configuration. We present a two-degree-of-freedom manipulator utilizing this fluid-based reconfigurable mechanism, which operates in three modes. We derive the fundamental equations necessary for analyzing kinematic properties such as workspace, manipulability, and singularity, including solutions for inverse kinematics and the Jacobian matrix. The manipulator's practical feasibility is validated through prototype testing of its mode-switching capabilities. Although the potential exists for improved control performance, tests confirm that the manipulator, with three operation modes utilizing fluid power transmission, can be effectively implemented. Furthermore, we evaluated the manipulator's design parameters based on established criteria to assess its effective movable range and the effect of switching kinematic properties, presenting two sets of practical design parameter values. This study also explores the possibility of constructing other types of manipulators with multiple operation modes based on similar principles.