There are two kinds of zero-level-fluctuations (z.l.f.‘s) in the magnetic head type torque sensors. The one is intrinsic and the other is extrinsic. The intrinsic z.l.f. is caused by the essential magnetic inhomogeneities at the surface area of the ferromagnetic shaft. in which the directional permeability in the 45° direction from the axis direction is different from that in the -450 direction at that area. The extrinsic one is caused by imperfect balance in the magnetic head type pickups (MP‘s) forming either a magnetic or an electric bridge circuit. In this case, any kind of nonuniformity in permeability and the air gap variation between MP's and the shaft surface cause significant z.l.f.'s. In this paper, the theory is presented by which the behavior of the extrinsic z.l.f. can be described for the magnetic head type torque sensor with L-R bridge configuration. A method for suppressing the extrinsic z.l.f. has been derived from the theory. The demonstration of the method is given using an as-ground carbon steel (S45C in JIS) shaft of 12mm diameter.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Electrical and Electronic Engineering