High resolution torque measurement on a rotating shaft with movement compensation

An apparatus for determining the torque imposed on a rotatable shaft. The shaft has at least four paired probes, paired horizontal probes and paired vertical probes. The horizontal probes are positioned 90 degrees apart from the vertical probes. If the shaft moves horizontally, the time of arrival detected by the first horizontal probes will be later than a nominal value and the time of arrival for the second horizontal probes will be earlier than a nominal value with the same amount of error. Combining data from the first and second horizontal probes will then automatically cancel out any error from horizontal motion. Similarly, combining data from vertical probes will eliminate the error due to vertical movement. Because any radial movement is a combination of horizontal and vertical movements, the use of the probes removes errors due to movement in any direction.