US5587931A
Expired / Lapsed
US
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Tool condition monitoring system
Assignee: 3060367 NOVA SCOTIA Co
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Filing: 1995-10-20
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Granted: 1996-12-24
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Expires: 2015-10-20
Abstract
Abstract A tool monitoring system monitors the condition of an electrically powered tool performing a cyclical operation. The tool monitoring system operates generally in two modes: learning mode and monitor mode. In learning mode, the tool monitoring system gathers statistical data on the power consumption of tools of the selected tool type during learning cycles. A power threshold is generated based upon the statistical data. The tool monitoring system then counts the number of crossings by each of the learning cycles of the power threshold and generates statistical data regarding the number of crossings. Preferably, the mathematical operation of wavelet packet transform is used to calculate the power threshold. Feature wavelet packets of the power consumption signal of the tool are calculated. The power consumption signal is then reconstructed from the feature wavelet packets and used to determine the power threshold. In monitor mode, the tool monitoring system counts the number of crossings of the power threshold by the power consumption signal of a tool in operation. The tool monitoring system identifies a worn tool when the number of crossings increases to a certain number relative to the crossings by the learning cycles.
Inventors
- 👤 Joel W. Jones
- 👤 Ya Wu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 10:34
CPC Classifications
G; G05; G05B; G05B23/00; G05B23/02; G05B23/0205; G05B23/0218; G05B23/0221; G05B23/0224; G05B23/0227; G05B23/0235; G05B2219/00; G05B2219/30; G05B2219/37; G05B2219/37256; G05B2219/37348; G05B2219/37457; G05B2219/37525; G05B2219/50; G05B2219/50197; G05B2219/50203
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
177 words
A method for monitoring the condition of an electrically powered tool of a selected tool type performing a cyclical task comprising the steps of: a. using a tool to perform a cyclical task and measuring a power consumption signal of said tool as said tool performs said cyclical task; b. decomposing said power consumption signal of said tool into components by converting said power consumption signal into time segments, each time segment having a digital value equivalent to the analog value of said signal at said time, and decomposing said time segments of said power consumption signal into different frequency components using a mathematical algorithm; c. selecting feature components of said power consumption signal; d. using said selected components of said power consumption signal to set a power threshold in a learning cycle; e. using a tool to perform a cyclic task and monitoring its power consumption signal; and f. identifying a worn condition of the tool of step e. based upon a comparison of said power consumption signal with said predetermined power threshold of step d.
Claim 2
Independent Claim
177 words
A method for monitoring the condition of an electrically powered tool of a selected tool type performing a cyclical task comprising the steps of: a. using a tool to perform a cyclical task and measuring a power consumption signal of said tool as said tool performs said cyclical task; b. decomposing said power consumption signal of said tool into components by converting said power consumption signal into time segments, each time segment having a digital value equivalent to the analog value of said signal at said time, and decomposing said time segments of said power consumption signal into different frequency components using a mathematical algorithm; c. selecting feature components of said power consumption signal; d. using said selected components of said power consumption signal to set a power threshold in a learning cycle; e. using a tool to perform a cyclic task and monitoring its power consumption signal; and f. identifying a worn condition of the tool of step e. based upon a comparison of said power consumption signal with said predetermined power threshold of step d.
Claim 3
Dependent Claim
22 words
The method for monitoring of claim 1, wherein the selected components of said step c. are reconstructed prior to said step d.
Claim 4
Dependent Claim
28 words
The method for monitoring of claim 1, wherein said step b. includes the step of applying said power consumption signal of said tool to a plurality of filters.
Claim 5
Dependent Claim
26 words
The method for monitoring of claim 1, wherein the decomposition of the signal includes the step of calculating wavelet packet transforms of said power consumption signal.
Claim 6
Dependent Claim
22 words
The method for monitoring of claim 1, wherein said power consumption signal of step e. is not decomposed prior to step f.
Claim 7
Dependent Claim
40 words
The method for monitoring of claim 1, wherein said step f. includes the steps of counting the number of crossings of said power threshold by said power signal, and comparing the number of crossings to an expected number of crossings.
Claim 8
Independent Claim
197 words
A method for monitoring the condition of an electric motor powered tool of a selected tool type comprising the steps of: a. using a tool to perform a cyclical task, and measuring a power consumption signal of said tool as said tool performs a cyclical task; b. generating a power threshold based upon said power consumption signal of said step a.; c. using a tool to perform a cyclical task, and measuring the power consumption signal of said tool said tool performs said cyclical task; d. comparing said power consumption signal of step c. to said power threshold by counting the number of crossings of said power threshold by said power consumption signal of said tool in step a., and counting the number of crossings of said power threshold by said power consumption signal of said tool in step c; and e. signalling a worn condition of said tool of step c when said power consumption signal of step c. reaches a predetermined level relative to said power threshold, said predetermined level being defined by when said crossings of said tool of step c. exceed said crossings of said tool of step a. by a predetermined amount.
Claim 9
Independent Claim
197 words
A method for monitoring the condition of an electric motor powered tool of a selected tool type comprising the steps of: a. using a tool to perform a cyclical task, and measuring a power consumption signal of said tool as said tool performs a cyclical task; b. generating a power threshold based upon said power consumption signal of said step a.; c. using a tool to perform a cyclical task, and measuring the power consumption signal of said tool said tool performs said cyclical task; d. comparing said power consumption signal of step c. to said power threshold by counting the number of crossings of said power threshold by said power consumption signal of said tool in step a., and counting the number of crossings of said power threshold by said power consumption signal of said tool in step c; and e. signalling a worn condition of said tool of step c when said power consumption signal of step c. reaches a predetermined level relative to said power threshold, said predetermined level being defined by when said crossings of said tool of step c. exceed said crossings of said tool of step a. by a predetermined amount.
Claim 10
Dependent Claim
19 words
The method for monitoring of claim 7, wherein both upper and lower thresholds are generated in said step b.
Claim 11
Dependent Claim
37 words
The method for monitoring of claim 8, wherein extreme thresholds are also set outside of said upper and lower thresholds, and signalling a failure should said power consumption signal of step c. exceed said extreme thresholds once.
Claim 12
Dependent Claim
23 words
The method for monitoring of claim 7, wherein said tool signals of said step b. are generated using a plurality of sample cycles.
Claim 13
Dependent Claim
19 words
The method of monitoring of claim 7, wherein said tools of steps a. and c. are the same tool.
Claim 14
Dependent Claim
75 words
The method for monitoring of claim 7, wherein said step b. includes the steps of: converting said power consumption signal of said tool into time segments, each time segment having a digital value equivalent to the analog value of said signal at said time; calculating wavelet packets of said power consumption signal of said tool; and reconstructing said power consumption signal of said tool by calculating inverse wavelet packet transform based on selected wavelet packets.
Claim 15
Independent Claim
125 words
A method for monitoring the condition of an electric motor powered tool of a selected tool type comprising the steps of: a. selecting a power threshold; b. using a tool to perform a cyclical task, and measuring a power consumption signal of said tool as said tool performs said cyclical task; c. counting the number of crossings of said power threshold by said power consumption signal of a learning cycle tool of said selected tool type, counting the number of crossings of said power threshold by said power consumption signal of said tool; and d. signalling a worn condition of said tool when said crossings of said tool exceed said crossings of said learning cycle tool by a predetermined amount in a predetermined time frame.
Claim 16
Independent Claim
125 words
A method for monitoring the condition of an electric motor powered tool of a selected tool type comprising the steps of: a. selecting a power threshold; b. using a tool to perform a cyclical task, and measuring a power consumption signal of said tool as said tool performs said cyclical task; c. counting the number of crossings of said power threshold by said power consumption signal of a learning cycle tool of said selected tool type, counting the number of crossings of said power threshold by said power consumption signal of said tool; and d. signalling a worn condition of said tool when said crossings of said tool exceed said crossings of said learning cycle tool by a predetermined amount in a predetermined time frame.
Claim 17
Dependent Claim
47 words
The method for monitoring of claim 13, wherein said step a. includes the steps of: measuring a power consumption signal of said learning cycle tool as it performs a cyclical task; and generating a power threshold based upon said power consumption signal of said learning cycle tool.
Claim 18
Dependent Claim
19 words
The method for monitoring of claim 14, wherein said tools of steps a. and b. are the same tool.
Claim 19
Independent Claim
269 words
A method for monitoring the condition of an electric motor powered tool of a selected tool type comprising the steps of: a. using a first tool to perform a plurality of cyclical tasks, and measuring a power consumption signal of said first tool as said first tool performs said plurality of cycles of cyclical task; b. decomposing said power consumption signal of each said cycle of said first tool into components; c. selecting feature components of said components of said power consumption signal; d. reconstructing said power consumption signal from said feature components; e. generating a power threshold based upon said reconstructed power consumption signal of said first tool, said power threshold including an upper limit for said power consumption signal; f. counting the number of crossings of said power threshold by said power consumption signal of said first tool while performing a plurality of cycles of said cyclical task; g. using a second tool to perform said cyclical task, and measuring the power consumption signal of said second tool as said second tool performs said cyclical task; h. counting the number of crossings of said power threshold by said power consumption signal of said second tool; i. comparing the number of crossings of said power threshold by said second tool with the number of crossings of said power threshold by said first tool; and j. signalling a worn condition of said second tool when the number of crossings of said power threshold by said second tool exceeds the number of crossings of said power threshold of said first tool by a predetermined amount in a predetermined time frame.
Claim 20
Independent Claim
269 words
A method for monitoring the condition of an electric motor powered tool of a selected tool type comprising the steps of: a. using a first tool to perform a plurality of cyclical tasks, and measuring a power consumption signal of said first tool as said first tool performs said plurality of cycles of cyclical task; b. decomposing said power consumption signal of each said cycle of said first tool into components; c. selecting feature components of said components of said power consumption signal; d. reconstructing said power consumption signal from said feature components; e. generating a power threshold based upon said reconstructed power consumption signal of said first tool, said power threshold including an upper limit for said power consumption signal; f. counting the number of crossings of said power threshold by said power consumption signal of said first tool while performing a plurality of cycles of said cyclical task; g. using a second tool to perform said cyclical task, and measuring the power consumption signal of said second tool as said second tool performs said cyclical task; h. counting the number of crossings of said power threshold by said power consumption signal of said second tool; i. comparing the number of crossings of said power threshold by said second tool with the number of crossings of said power threshold by said first tool; and j. signalling a worn condition of said second tool when the number of crossings of said power threshold by said second tool exceeds the number of crossings of said power threshold of said first tool by a predetermined amount in a predetermined time frame.
Claim 21
Dependent Claim
52 words
The method for monitoring the condition of an electrically powered tool of claim 16, wherein said steps b-d include the steps of: calculating feature wavelet packets of said power consumption signal of said first tool; and reconstructing said power consumption signal from the inverse wavelet packet transform of the feature wavelet packets.
Claim 22
Dependent Claim
24 words
The method for monitoring the condition of an electrical power tool of claim 16, wherein said first and second tools are the same tool.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-12-24 | 2000-06-24 | 2000-12-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-12-24 | 2004-06-24 | 2004-12-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-12-24 | 2008-06-24 | 2008-12-24 | $7700.00 | Window Closed / Lapsed |