2PPaRR-2PPaRU: Design, analysis, and optimization of a new 3T1R parallel manipulator with rotational pitch motion

Abstract

A new 3T1R parallel manipulator (PM) 2PPaRR-2PPaRU with rotational pitch motion is proposed in this paper. In such a mechanism, there are four limbs connected to the moving platform (MP) through several revolute joints and universal joints, and all actuated joints are prismatic joints with an axis along a vertical direction. Mobility and motion characteristics are verified by constraint screw theory. The inverse kinematic solutions and the singularity configurations are derived through kinematic analysis. Next, the workspace analysis and the connection between [Formula: see text] and the volume of the reachable workspace are performed. The local motion/force transmission index is selected to evaluate the local transmission performance of 2PPaRR-2PPaRU PM. Finally, the global motion/force transmission index and the volume of reachable workspace are considered simultaneously to optimize the structural parameters. The 2PPaRR-2PPaRU PM with improved local transmission performance and reachable workspace has been achieved after optimization.

Measuring Performance: Metrics for Manipulator Design, Control, and Optimization

“…This region can be obtained through different definitions with different results [7]. Common definitions for optimization include the reachable workspace (reachable points with at least one orientation [47,48]), translation workspace (reachable points with a given orientation [49][50][51]), orientation workspace (reachable orientations in a given point [52,53]), and the dexterous workspace (reachable points with all orientations [54][55][56][57]). When evaluating a robot in term of its workspace, we usually tend to use intrinsic metrics, computing workspace volume by considering the robot's geometrical constraints, i.e., joint limits, actuation range, self-collision, singular configurations.…”