Direct Drive θ-Z Motor for Rotary and Linear Motion

Abstract

A multi-dimensional positioning mechanism, along with high speed and high accuracy, is necessary for an industrial machine. The 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, high accuracy, and miniaturization are achieved without using machine elements such as ball screw and belt.  In this paper, we described the structure and operating principle of the θ-z motor, and the sensor which can detect the θ-axis angle and the z-axis position. In addition, we consider the design method for the minimization of copper loss by the shape of permanent magnet and coil. Furthermore, we inspected the characteristics of torque, thrust, and repeatability by using the prototype.