In part I of this paper (previous issue of Robotica) a dual stage system with the coarse and fine actuators is adopted to achieve sub-micron accuracy with a large working space for the proposed new three degree-of-freedom (DOF) miniaturized micro parallel mechanism with high mobility and one type of the architecture with vertical actuator locations in all three legs (C-VV type) among six possible coarse actuator architectures is selected for the coarse actuator architecture.

In this part of the paper, an optimal kinematic parameter set is determined for the selected coarse actuator architecture. To determine this set, the design tool of the physical model of the solution space (PMSS) and the evaluation of the conditioning index (CI) and global mobility conditioning index (GMCI) are used. The basic size of the micro parallel mechanism is 45.0 mm×22.5 mm×22.9 mm with 100° mobility, the workspace 5.0 mm (y-axis)×5.0 mm (z-axis), and sub-micron resolution. After finishing the design of the main coarse actuator architecture, one architecture among six possible fine actuator architectures is selected to achieve sub-micron positioning accuracy based on the requirements of the continuous fine motion and smaller platform resolution. The selected coarse-and-fine actuator combination is used for the micro positioning platform for laser-machining application.

Using a coarse-and-fine actuator combination (dual stage system), a new design of the three degree-of-freedom (DOF) micro parallel positioning platform with high mobility, high accuracy, and a large working space is proposed. To achieve these three DOFs and implement the dual stage system, there are six possible architectures for the coarse and fine actuators, respectively. This paper is organized in two parts. Part I treats the kinematic analysis of each architecture and the problem of selecting the correct coarse actuator architecture. Inverse kinematics and Jacobian matrices for six types of coarse actuator architectures are derived and one proper coarse actuator architecture is selected based on the mobility (rotational capability) analysis, condition number evaluation of the Jacobian matrix, and manufacturability consideration. Part II on real machine design will follow in the next issue of Robotica.