EP0459336A1
Expired / Lapsed
EP
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Ultrasonic distance measuring system
Assignee: Deere and Co
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Filing: 1991-05-27
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Granted: —
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Expires: 2011-05-27
Abstract
Abstract A distance sensing system (10) includes an ultrasonic transducer (XM1), a transceiver (12) and a microcontroller-based signal processing unit (14). The transducer (12) periodically generates and directs towards the terrain a dual frequency ultrasonic signal. Echo signals from the ground and/or any intervening crop or trash are reflected back to the transducer (12) and are processed. The system generates amplified and filtered echo envelope signals. Leading and trailing edge times are determined as the times the echo signals cross a threshold value which is a certain proportion of a maximum echo amplitude value. A near distance value is derived from the leading edge time of the first echo which exceeds a minimum amplitude. A far distance value is determined as the trailing edge time of the last echo signal which has an amplitude which exceeds a certain value. Multiple echo time and amplitude values are derived from the maximum amplitude echo. These values are used to prevent echoes which occur after the multiple echo time with less than a certain amplitude from being used in the determination of the far distance value. This far distance value represents the distance to ground and weaker, earlier echoes from trash or crop and later, multiple echoes may be ignored.
Inventors
- 👤 James J. Phelan
- 👤 Jeffrey C. Hawkinson
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 16:19
CPC Classifications
A; A01; A01B; A01B63/00; A01B63/02; A01B63/10; A01B63/111; A01B63/1112; A01B63/114; G; G01; G01S; G01S15/00; G01S15/02; G01S15/06; G01S15/08; G01S15/10; G01S15/88; G01S7/00; G01S7/52; G01S7/523; G01S7/526; G01S7/527; G01S7/539
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
125 words
A distance measuring system having a transducer (XM1) for generating at a transmit time a transmit pulse towards a surface the distance to which is to be measured and for receiving a plurality of echo signals reflected from the surface and from other surfaces exposed to the transmit pulse and having means for determining a trailing edge time for each echo signal, the trailing edge time being defined as the time at which an amplitude of an echo signal crosses a threshold (AMPTH) with a negative slope, characterized by: means for determining a distance value (Xn, Xf) from the transmit time and the trailing edge time of the last of said plurality of echo signals which has an amplitude which exceeds a minimum amplitude (AREQ).
Claim 2
Dependent Claim
24 words
The distance measuring system of claim 1, wherein the minimum amplitude is a certain proportion of a maximum amplitude (ADMX) of the echo signals.
Claim 3
Independent Claim
245 words
A method for measuring a distance between a transducer (XM1) and a surface, comprising the following steps: a) transmitting at a transmit time an acoustic signal from the transducer (XM1) so that the transducer (XM1) receives reflected echo signals, including an echo signal reflected from the surface, and b) determining amplitude and time data for a maximum echo signal having a peak amplitude (ADMX) which is larger than the peak amplitude of all the other echo signals received by the transducer (XM1), characterized by: c) from the amplitude and time data for the maximum echo signal, determining an estimated multiple echo amplitude (ADREQ) and an estimated multiple echo time (cteme) for an echo signal which could result from multiple reflections of the transmit pulse; d) determining whether the amplitude of a particular echo signal exceeds a certain minimum amplitude (AREQ); e) if the amplitude of said particular echo exceeds said certain minimum amplitude (AREQ) and the particular echo signal was received before the estimated multiple echo time (cteme) determining the distance value from the transmit time and a time of said particular echo signal; and f) if the amplitude of said particular echo signal exceeds the certain minimum amplitude (AREQ) and said particular echo signal was received not before the multiple echo time (cteme) and the amplitude of said particular echo signal exceeds the estimated multiple echo amplitude (ADREQ), determining the distance value from the transmit time and a time of said particular echo signal.
Claim 4
Dependent Claim
27 words
The method of claim 3, wherein the distance value is determined from the transmit time and from a trailing edge time (CTE[i]) of the particular echo signal.
Claim 5
Dependent Claim
20 words
The method of claim 3 or 4, wherein the multiple echo amplitude (ADREQ) differs from the certain minimum amplitude (AREQ).
Claim 6
Independent Claim
33 words
The method of any of the claims 3, 4 or 5, wherein minimum amplitude is derived as a certain proportion of a largest amplitude of all echo signals received by the transducer (XM1).
Claim 7
Independent Claim
37 words
The method of any of the preceding claims 3 to 6, wherein the estimated multiple echo amplitude (ADREQ) is derived as a certain proportion of a largest amplitude (ADMX) of all echo signals received by the transducer.
Claim 8
Independent Claim
60 words
The method of any of the preceding claims 3 to 7, wherein if the particular echo signal was received before the multiple echo time (cteme), the distance value is determined from the transmit time and from a trailing edge time (CTE[i]) of said particular echo if said particular echo has a distance-corrected amplitude (EA[i]) which exceeds a certain minimum amplitude.
Claim 9
Independent Claim
61 words
The method of any of the preceding claims 3 to 8, wherein the distance value is determined from the transmit time and from a trailing edge time (CTE[i]) of the particular echo signal, the trailing edge time of an echo signal corresponding to a time at which a distance corrected amplitude (EA[i]) of the echo signal crosses a threshold value (AMPTH).
Claim 10
Independent Claim
60 words
The method of any of the preceding claims 3 to 9, wherein the distance value is determined from the transmit time and from a trailing edge time of the particular echo signal, the trailing edge time of an echo signal corresponding to a time at which an amplitude of the echo signal is decreasing and crosses a threshold value (AMPTH).
Claim 11
Dependent Claim
140 words
A distance measuring system comprising a transceiver (12, XM1) for transmitting a transmit signal towards a surface, the distance to which is to be measured, and for receiving echo signals reflected from the surface, characterized by: a plurality of amplifiers (18, 20a, 20b), each receiving the echo signals (R), having a different amplifier gain generating a different amplified echo signal; a signal processing unit (14) receiving the amplified echo signals (E x 1, E x 5, E x 25, E x 125) from all of the amplifiers (20a, 20b), the unit (14) comprising means for deriving a distance value (Xn, Xf) from the amplified echo signal from a selected one of the amplifiers (20a, 20b); and the unit (14) further comprising means (202, 204) for automatically changing said selection as a function of the amplitude of the amplified echo signal.
Claim 12
Dependent Claim
86 words
The distance measuring system of claim 11, wherein the means for automatically changing comprises means (206) for determining a maximum amplitude of the amplified echo signals; means (208) for comparing the maximum amplitude to a first limit value and selecting a channel with a smaller gain if the maximum amplitude exceeds the first limit value; means (208) for comparing the maximum amplitude to a second limit value and selecting a channel with a higher gain if the maximum amplitude is less than the second limit value.
Claim 13
Dependent Claim
94 words
The distance measuring system of claim 11 or 12, further comprising means (208) for setting a threshold value (AMPTH); means for determining leading edge times as the times at which distance corrected echo signal amplitudes (EA[i]) cross the threshold value (AMPTH) with a positive slope; means for determining trailing edge times as the times at which distance corrected echo signal amplitudes (EA[i]) cross the threshold value (AMPTH) with a negative slope; and means for deriving distance values (216, 220) from a transmit time of the transmit signal and the leading and trailing edge times.
Claim 14
Dependent Claim
33 words
The distance measuring system of claim 12, 13 or 14, further comprising means (224) for automatically adjusting the threshold value as a function of a distance corrected maximum amplitude of the echo signals.
Claim 15
Dependent Claim
56 words
The distance measuring system of any of the preceding claims 11 to 14, wherein a near distance value (Xn) is determined from the leading edge time of the first amplified echo signal which has a distance corrected amplitude (EA[i]) which exceeds a certain fraction of a distance corrected maximum amplitude of the amplified echo signals (AMX).
Claim 16
Dependent Claim
46 words
The distance measuring system of any of the preceding claims 11 to 15, wherein a far distance value (Xf) is determined from the trailing edge time (CTE[i]) of the last amplified echo signal which has a distance corrected amplitude which exceeds a certain minimum amplitude (AREQ).
Claim 17
Dependent Claim
23 words
The distance measuring system of any of the preceding claims 11 to 16, further comprising means (224) for slew-rate limiting the distance values.
Claim 18
Dependent Claim
218 words
A distance measuring system comprising a transducer (XM1) for generating at a transmit time a transmit pulse towards a surface the distance to which is to be measured and for receiving a plurality of echo signals reflected from the surface and from other surfaces exposed to the transmit pulse; means for determining amplitude and time data for a maximum echo signal having a peak amplitude (ADMX) which is larger than the peak amplitude of all the other echo signals, characterized by: means for, from the amplitude and time data for the maximum echo signal, determining an estimated multiple echo amplitude (ADREQ) and an estimated multiple echo time (cteme) for an echo signal which would result from multiple reflections of the transmit pulse; and means for determining a trailing edge time (CTE[i]) for each echo signal, the trailing edge time being defined as the time at which an amplitude of an echo signal crosses a threshold (AMPTH) with a negative slope; and means for determining a distance value (Xf) from the transmit time and the trailing edge time of the last of said plurality of echo signals which has an amplitude which exceeds a minimum amplitude (AREQ) and which exceeds the estimated multiple echo amplitude (ADREQ) if said last echo signal occurs after the estimated multiple echo time (cteme).
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