A Novel Rotary-Linear Machine Based on E-Core Flux-Switching Structure for Robotic Application

Rotary-linear machines (RLM), as a class of devices with two degrees of freedom, are increasingly being integrated into automation systems and industrial robots due to their compact design advantages. However, current rotary-linear machines typically rely on conventional rotary motors coupled with ball screws in their linear motion, whose efficiency and extent of integration are low. Aiming to increase force density and efficiency of the machine in a compact design, this paper presents a novel RLM based on an E-core flux-switching design to achieve linear motion with longitude flux and rotation motion with transverse flux. In the linear direction, tooth-tip PMs are utilized to enhance flux density in the air gap and improve force density thereafter, and in the rotational direction, transverse flux is employed to eliminate the coil end, which can increase efficiency. Motions in two directions have been decoupled by utilizing flux in flux-switching teeth (FST) and fault-tolerant teeth (FTT). This paper analyzes the working principles and flux paths in both operational directions. The finite element analysis (FEA) results verified the proposed design's feasibility, and the two-direction motions are decoupled.