# US 5,703,283 A · Detrending engine positional data for rotating position encoders > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,703,283 A - Document ID: US5703283A - Status: Granted - Kind: A - Application number: 08/562,532 - Filed: 1995-11-24 - Granted: 1997-12-30 - Earliest claimed: 1995-11-24 - Assignees: Motorola, Inc. - Inventors: Michael A. McClish; Marvin L. Lynch; Margaret A. Selfe; Gregory Steinl; Donald J. Remboski, Jr. - Web page: https://patentgrep.com/patent/US5703283A ## CPC - G01M 15/06: by monitoring positions of pistons or cranks - G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR ## Abstract A method for detrending engine positional data includes acquiring positional encoder data over a plurality of consecutive engine revolutions as the engine is decelerating. Then, a trend (207) in the acquired positional encoder data consistent with behavior occurring at less than a frequency of one cycle per engine revolution is identified. Next, corrected positional encoder data (208) is generated dependent on removing the identified trend (207). ## Claims ### Claim 1 A method for detrending engine position data for rotating position encoders coupled to an engine comprising the steps of: acquiring engine position data over a plurality of consecutive engine revolutions as the engine is decelerating; determining a continuously decelerating trend in the acquired engine position data consistent with behavior occurring at a frequency of less than one cycle per engine revolution; and providing corrected engine position data by eliminating the determined continuously decelerating trend from the acquired engine position data. ### Claim 2 (depends on 1) A method in accordance with claim 1 wherein the engine position data is representative of time durations between successive engine positions. ### Claim 3 (depends on 2) A method in accordance with claim 2 further comprising a step of: constructing an encoder profile dependent on the corrected engine position data. ### Claim 4 (depends on 3) A method in accordance with claim 3 further comprising a step of: providing corrected engine position data in a fueled engine dependent on the constructed encoder profile. ### Claim 5 (depends on 2) A method in accordance with claim 2 wherein the step of providing corrected engine position data provides corrected engine position data dependent on a difference between the acquired engine position data and the determined continuously decelerating trend. ### Claim 6 (depends on 5) A method in accordance with claim 5 further comprising a step of: determining an encoder profile dependent on the corrected engine position data. ### Claim 7 (depends on 6) A method in accordance with claim 6 wherein the step of acquiring an engine position data over a plurality of consecutive engine revolutions acquires the engine position data over at least eight engine revolutions. ### Claim 8 (depends on 1) A method in accordance with claim 1 wherein the step of acquiring an engine position data comprises a step of acquiring an engine position data over a plurality of consecutive engine revolutions as the engine is not fueled. ### Claim 9 A method for detrending engine position data for a rotating position encoder coupled to an engine that provides position data corresponding to successively spaced position marks as an engine rotates, the method comprising the steps of: acquiring a multitude of continuously increasing time differences occurring between the successively spaced position marks over a plurality of consecutive engine cycles as the engine is continuously decelerating; determining a mean time difference for each engine cycle of the plurality of engine cycles dependent on a portion of the multitude of time differences occurring between the successively spaced position marks; and providing a corrected delta-time associated with each successively spaced position marks by eliminating a portion of the multitude of continuously increasing time differences occurring between the successively spaced position marks from the mean time difference for each engine cycle of the plurality of engine cycles. ### Claim 10 (depends on 9) A method in accordance with claim 9 wherein the step of acquiring a multitude of continuously increasing time differences over a plurality of consecutive engine revolutions acquires the multitude of time differences over at least eight engine revolutions. ### Claim 11 (depends on 10) A method in accordance with claim 10 wherein the step of acquiring a multitude of continuously increasing time differences comprises a step of acquiring a multitude of continuously increasing time differences over a plurality of consecutive engine revolutions as the engine is not fueled. ### Claim 12 (depends on 9) A method in accordance with claim 9 further comprising a step of: constructing an encoder profile dependent on the corrected delta-times associated with each of the successively spaced position marks. ### Claim 13 (depends on 12) A method in accordance with claim 12 further comprising a step of: providing encoder profile corrected delta-times associated with each of the successively spaced position marks in a fueled engine dependent on the constructed encoder profile. ### Claim 14 (depends on 11) A method in accordance with claim 11 further comprising a step of: constructing an encoder profile dependent on the corrected delta-times associated with each of the successively spaced position marks. ### Claim 15 (depends on 14) A method in accordance with claim 14 further comprising a step of: providing encoder profile corrected delta-times associated with each of the successively spaced position marks in a fueled engine dependent on the constructed encoder profile. ### Claim 16 A method for detrending profile correction factors for a rotating position encoder that provide position data corresponding to successively spaced position marks as an engine rotates, the method comprising the steps of: acquiring a multitude of continuously increasing time differences occurring between the successively spaced position marks over a plurality of consecutive engine revolutions as the engine is continuously decelerating; determining a mean time difference between successively spaced position marks for each engine revolution of the plurality of engine revolutions dependent on a portion of the multitude of continuously increasing time differences; and determining a trend line corresponding to the portion of continuously increasing time differences of the acquired multitude of time differences for each engine revolution; determining a difference between a magnitude represented on the trend line and a zero slope line passing through a mean time value for each of the successively spaced position marks and for each engine revolution of the plurality of consecutive engine revolutions and providing error values dependent thereon; and providing a corrected delta-time associated with each of the successively spaced position marks dependent on subtracting each of the error values from the acquired multitude of continuously increasing time differences. ### Claim 17 (depends on 16) A method in accordance with claim 16 further comprising a step of: constructing an encoder profile dependent on the corrected delta-times associated with each of the successively spaced position marks. ### Claim 18 (depends on 17) A method in accordance with claim 17 further comprising a step of: providing corrected engine position data in a fueled engine dependent on the constructed encoder profile. ### Claim 19 An apparatus for detrending engine position data comprising: a sampler for acquiring an engine position data over a plurality of consecutive engine revolutions as the engine is continuously decelerating; and a signal processor for determining a continuously decelerating trend in the acquired engine position data consistent with behavior occurring at a frequency of less than one cycle per engine revolution and providing a corrected engine position data by eliminating the determined continuously decelerating trend. ### Claim 20 (depends on 19) An apparatus in accordance with claim 19 wherein the signal processor constructs an encoder profile dependent on the corrected delta-times associated with each of the successively spaced position marks. ### Claim 21 (depends on 20) An apparatus in accordance with claim 20 wherein the signal processor provides corrected engine position data in a fueled engine dependent on the constructed encoder profile.