Comparative evaluation of linear-rotary actuator topologies for highly dynamic applications

A Linear-Rotary Actuator (LiRA) is an electrical machine whose mover can move linearly and rotate as a direct drive (without mechanical transmissions/gearboxes). Such actuators are successfully used in various applications such as pick-and-place machines that mount components on Printed Circuit Boards (PCBs), servo actuation of gearboxes, and in robot arms and/or end effectors. In order to design a compact LiRA with high dynamics, two different LiRA topologies are compared in this paper. A fair comparison is obtained by fixing the outer dimensions of the examined LiRA topologies (diameter and length). Electrical loading of the machines is determined using a simple thermal model, and an optimization based on finite element analysis is carried out. Performance criteria, such as circumferential and axial accelerations as well as maximum axial forces of all analyzed machines are compared. Moreover, metrics like total machine mass and volume of the used permanent magnets are included in the evaluation.