Employing variable reluctance direct-drive motion actuators in high performance manufacturing machines

Most advanced manufacturing processes require high-speed and high precision motion control for material transfer, packaging, assembly, and electrical wiring. Examples are surface mounting of electronic components, wire bonding of semiconductor chips, and assembly of watches and hard disks. To achieve precise motion control, most of these high-performance manufacturing machines use rotary DC or AC motors as the prime motion actuator, and couple their output shafts to mechanical motion translators (e.g. reduction gear, belt, ball screw, etc.). Though this is the most widely used method, it has disadvantages of reduced accuracy, complex mechanical structure, difficult adjustments and alignments, high production cost, and low reliability. In this paper, the author proposes a new direction in high performance machine design, and suggests that future high performance motion systems should be designed through "simplifying the mechanics through specialized direct-drive actuators and advanced control methodologies". For this purpose, this paper investigates a class of variable reluctance (VR) direct-drive motion actuators for high performance machines. The paper looks into several specialized motion actuator system design, (including limited stroke actuators, embedded artificial limb, linear motion devices, and planar motion devices), highlights their features and advantages, and describes the challenges of controlling these devices.