Miniaturized magnetoelastic torque transducers

Torque transducers based on circumferentially polarized band technology are shown to be scalable downward to accommodate torque measurements to at lea st low mN.m ranges. Shaft diameter for any required torque range is determi ned by material strength, while band width and separation are selected prim arily to meet specific field detector requirements. Experiments verify the theoretically based expectation that the fields arising with the applicatio n of torque to properly scaled mini-shafts are of similar intensity to thos e from larger shafts. A torque transducer of simple construction with a 0.7 9 mm diameter alloy steel shaft having a coercivity greater than 60 Oe, tog ether with Hall effect field detectors exhibits suitable characteristics fo r torque measurement in the +/-25 mN.m range.