Patent ID: 8471194

Claim:
A rotary encoder for use with a valve actuator, the rotary encoder comprising: a plurality of encoding wheels, each of the plurality of encoding wheels comprising a plurality of coding sections for encoding multiple positions of the valve actuator; a timing mechanism for generating rotational speed data from the valve actuator, wherein the timing mechanism comprises a timing wheel having a plurality of timing marks equally spaced in a concentric pattern around the timing wheel; a plurality of double set of redundant encoder sensors for monitoring each coding section of the plurality of coding sections of each of the plurality of encoding wheels, wherein each double set of redundant encoder sensors comprises a first sensor positioned on a first side of a corresponding coding wheel and a second sensor positioned on a second, opposing side of the corresponding coding wheel, and wherein the first sensor and the second sensor each comprise an emitter and a detector positioned adjacent to the emitter; a double set of redundant timer sensors for monitoring the plurality of timing marks of the timing wheel, wherein the double set of redundant timer sensors comprises a first sensor positioned on a first side of the timing wheel and a second sensor positioned on a second, opposing side of the timing wheel, and wherein the first sensor and the second sensor each comprise an emitter and a detector positioned adjacent to the emitter; and a processor in communication with the plurality of double set of redundant encoder sensors of each of the plurality of encoding wheels and the double set of redundant timer sensor of the timing mechanism, wherein the processor is operable to transform the rotational speed data generated by the timing mechanism from a time domain to a frequency domain to generate frequency data, and to compare the generated frequency data with a baseline frequency data.