Exploring the geometric design of a 3T1R parallel-based machine tool to achieve a targeted workspace

This study presents a novel approach to the design of a 3T1R parallel-based machine tool by incorporating local and global dexterity indices. The methodology focuses on the synthesis of geometric dimensions to optimize the mechanism’s performance. Initially, the paper provides a brief overview of the inverse kinematics of the mechanism and develops a 2-degrees-of-freedom (2-DoF) design based on the desired workspace, which is defined as the largest enclosed operational area. The research also evaluates the kinematic precision and distance singularity of the manipulator using global and local dexterity indices. Subsequently, the optimal dimensions for the individual components of the 3T1R parallel-based machine tool are determined by combining two 2-DoF mechanisms that have undergone design improvements. The study then discusses various conditions related to each component and establishes enhanced dimensions for the 3T1R manipulator to achieve the desired workspace. The design process considers the appropriate range of global and local dexterity indices to improve the performance of the 3T1R manipulator components within the targeted workspace. With this enhanced design, the 3T1R manipulator is capable of achieving four degrees of motion at any given position, while avoiding singular points outside the workspace boundaries. This methodology can be applied to a wide range of parallel-based machine tools.