Direct versus Indirect measurement of shaft angle
As a rule, it's preferable to measure directly the position or speed of the object that you are interested in. In many cases, practical problems of physical environment or limited space mean that this can be a challenge, particularly when measuring the angle of shafts with a diameter greater than a couple of inches. The traditional approach is to measure angular position or speed indirectly - typically inferring the shaft's position from measurements made elsewhere. Mark Howard of Zettlex Ltd describes the traditional approach and a new, direct approach enabled by inductive sensors
