A Direct Drive θ‐Z Motor for Rotary and Linear Motion

Abstract

SUMMARYA multidimensional positioning mechanism, along with high speed and high accuracy, is essential for an industrial machine. A positioning machine operates precisely in both vertical linear motion (z‐axis) and rotary motion (θ‐axis). A ball screw mechanism is used for the z‐axis whereas a servo motor is used for the θ‐axis. We developed a direct drive θ‐z motor for rotary and linear motion. Torque and thrust are generated directly by the mover. Thus, high speed and high accuracy as well as miniaturization are achieved without using machine elements such as a ball screw and belt. In this paper, we describe the structure and operating principle of the θ‐Z motor, and the sensor that can detect the θ‐axis and the z‐axis position. In addition, we consider a design method that minimizes copper loss by taking advantage of the shape of the permanent magnet and coil. Furthermore, using a prototype we evaluated the characteristics of torque, thrust, and repeatability.