Abstract: An embodiment of the invention generally relates to a temperature-independent method of determining an engine health parameter, namely stand-off distance, between an eddy current sensor and a conductive element. The method includes receiving a signal from the eddy current sensor and demodulating a waveform from the received signal. The method also includes determining a predetermined set of substantially temperature-independent parameters from the waveform and determining the stand-off distance based on the predetermined set of substantially temperature-independent parameters.

Abstract: An embodiment of the invention generally pertains to a method of compensating for temperature variations in an eddy current sensor signal. The method may include the steps of receiving an initial signal from an eddy current sensor (ECS) in response to a conductive element passing the ECS and sensing an ECS temperature and an ECS board temperature. The method may also include determining a subset of correction coefficients based on the ECS temperature and the ECS board temperature and determining a temperature correction factor from the subset of correction coefficients. The method may then compute a temperature corrected signal from the initial signal and the temperature correction factor.

Abstract: A motor has a rotor for controlling a parameter of an instrumentality, such as a blade or a blade flap. The rotor is positioned about the drive shaft of the instrumentality and rotates at the same average angular velocity of the drive shaft. The instrumentality is controlled by applying to the instrumentality a physical displacement signal that is generated by the phase relationship of the rotor of the motor with respect to the angular position of the drive shaft. A plurality of permanent magnets proximate the periphery of the rotor cooperate with a plurality of stator polepieces and electromagnetic coils. The current flowing through the coils is reversed each time that the rotor advances by the angular space of one permanent magnetic pole. The strength and polarity of the current flowing through the coils controls the direction and displacement of the rotor with respect to a neutral phasing of the rotor with respect to the drive shaft.

Abstract: In many uses of electrical motors, the interaction of a tool being powered, e.g., a milling machine, and the workpiece being worked on by the motor induces mechanical vibrations which adversely affect the functioning of the tool as well as inducing wear producing vibrations in the motor rotor shaft. Damping of such vibrations is achieved by deliberately inducing internal unbalanced forces on the motor rotor shaft for counteracting the externally induced vibrations. Such internal unbalanced forces are produced by the use of additional currents in the main stator coils for generating additional, unbalanced force generating magnetic fields. A mathematical analysis of the process is provided.