System and Method for Object Position Estimation Based on Ultrasonic Reflected Signals

Content Provider	The Lens
Related Links	https://www.lens.org/lens/patent/011-963-556-359-619/frontpage
Language	English
Publisher Date	2019-12-25
Access Restriction	Open
Alternative Title	System Und Verfahren Zur Lagebestimmung Eines Objektes Auf Basis Von Reflektierten Ultraschallsignalen Système Et Procédé D'estimation De Position D'objet Sur La Base De Signaux Réfléchis Par Ultrasons
Content Type	Text
Resource Type	Patent
Date Applied	2011-11-16
Agent	Schmidbauer, Andreas Konrad
Applicant	Qualcomm Inc
Application No.	15151597
Claim	A system for small space positioning comprising: a transmitting element (123) at a fixed and known location, configured for transmitting a modulated continuous ultrasonic wave, wherein the modulated continuous ultrasonic wave comprises a continuous ultrasonic carrier signal part and a predetermined ultrasonic base-band signal modulated onto said carrier signal part, the transmitting element configured to transmit said modulated continuous ultrasonic wave over a range in which an object to be positioned may appear; and at least one receiving element (121, 122) configured for receiving signals transmitted by the transmitting element and reflected by the object, said received signals comprising said modulated continuous ultrasonic wave; and a position detection element (152) configured to determine a position of the object from analysis of both the carrier signal part and the base-band signal received from the reflected signal, wherein the analysis of both the carrier signal part and the base-band signal includes phase analysis, wherein said position detection element (152) is configured for performing correlation between a modulated continuous wave received by the at least one receiving element and an expected modulated continuous wave. The system according to claim 1, wherein the modulated continuous wave is pre-determined and the expected modulated continuous wave comprises a replica of the modulated continuous wave transmitted by the transmitting device; and wherein said replica of the modulated continuous wave comprises a channel model for modeling passage of said waveform from said positional element to said waveform decoding unit, thereby to provide a reference signal against which to identify said most likely distance. The system according to claim 1, wherein the at least one receiving element is configured for determining base-band and carrier signal correlation curves from the correlation between the received modulated continuous wave and the expected modulated continuous wave; and wherein the correlation curves comprise respective absolute, real and imaginary curves, and said at least one receiving element is configured for determining at least one peak in a respective absolute correlation curve and at least one peak in a respective real correlation curve. The system according to claim 1, further configured to use one member of the group consisting of: a known distance between said transmitting elements and said receiving elements (121, 122), and a fixed link, for mutual synchronization; and/or wherein said position detection element (152) is configured to remove leakage of a direct signal path and of static artifacts using differential detection; and optionally wherein said differential detection comprises subtracting each input sample from a preceding sample and then applying at least one member of the group consisting of complex correlation and cross correlation between successive frames, said differential detection being carried out to determine a Time Of Arrival; and/or wherein said position detection element (152) is configured to use a time of arrival of said leakage with a known distance between said transmitting element and said at least one receiving element (121, 122), to calculate there from an air temperature. The system according to claim 1, wherein said position detection element (152) is configured to remove leakage of a direct signal path using complex correlation subtraction; The system according to claim 5, wherein an indication of presence of an object is obtained by detecting change in at least one member of the group consisting of energy and Signal-To-Noise ratio; and optionally wherein energy detection comprises correlating an input signal with a known template and then integrating an energy of a correlation output over all time distances possible; and/or wherein said signal to noise calculation comprises integration of an energy of all possible values of a correlation in a possible distance range, and dividing by an average of a noise estimation at a correlation output at a distant time-shift. The system according to claim 5, wherein said position detection element is configured to: determine a first time at which there is no object placed in a detection area, to calculate and average at said first time a complex correlation, an absolute value of said correlation being saved; at a second time, when an object to be positioned is placed in said detection area, determining a second absolute value of a correlation result obtained at said second time and subtracting said second absolute value from the saved absolute value, thereby to extract an absolute correlation of the reflected signal without said direct path leakage; using said absolute correlation to extract a Time-Of Arrival of the reflected signa The system according to claim 1, wherein said position detection element (152) is configured to remove leakage of a direct signal path using time-domain subtraction; and optionally wherein said position detection element (152) is configured to: determine a first time at which there is no object placed in a detection area, to average and save a signal for a period on N frames, wherein each frame is a duration of a transmitted sequence; at a second time, when an object to be positioned is placed in said detection area, subtracting time-domain values of a received signal from the saved averaged values of the time-domain signal calculated at said first time, thereby extracting time-domain values of the reflected signal without the leakage of the direct path; and carrying out a complex correlation to extract a Time-Of Arrival of the reflected signa The system according to claim 1, wherein said position detection element (152) is configured to calculate a Time-Of-Arrival trajectory per receiving element from a complex-correlation value calculated per frame, wherein said frame equals a duration of a transmitted sequence, or a template; and optionally wherein said position detection element (152) is configured to extract said Time-Of-Arrival from said complex correlation by taking an absolute vale of a correlation above a preset threshold and integrating using a Center of Mass equation; and/or wherein said position detection element (152) is further configured to filter an extracted Time-Of-Arrival trajectory using one member of the group consisting of a linear filter, an IIR filter, an FIR filter, a non-linear filter, a Median filter and a combination of a linear and a non-linear filter; and/or wherein said Time-Of-Arrival extracted by said complex correlation is calculated using a maximum of an absolute value of the complex correlation that has passed a set threshold; and optionally wherein said set threshold is set to be M times or M bigger than an average value of the noisy correlation wherein M is a predetermined constant. The system according to claim 1, wherein said position detection element is configured to use a two dimensional search for fine tuning extraction of a first path Time-Of-Arrival; and optionally wherein said two dimensional search comprises searching for multiple reflections of a same originating signal, said multiple reflections being characterized in terms of at least one of a respective time, amplitude and phase of a corresponding complex correlation. The system according to claim 1, wherein said position detection element (152) is further configured to use a second receiver, and to compare a Time-Of-Arrival trace from each receiver; and optionally wherein said position detection element (152) is configured to extract a trace direction from each receiver respectively, thereby to distinguish between an Up-To-Down movement and a Down-To-Up movement; and optionally wherein a velocity is extracted from an averaged value of the differentiated TOA traces; and/or wherein said distinguishing comprises: estimating a first derivative of the respective trace; averaging and comparing to zero; if the averaged value is greater than zero then determining that the direction is Down To Up, and if the value is lower than zero, then determining that the direction is Up To Down; and optionally wherein said determining is made to exclude a trace part wherein the derivative equals zero. The system according to claim 11, wherein said position detection element (152) is further configured to use respective time of arrival trajectories at each receiver respectively to distinguish between Left-To-Right and Right-To-Left movement; and optionally wherein said distinguishing comprises finding a three part formation of a decrease followed by a constant followed by an increase in Time of Arrival; and optionally wherein said distinguishing comprises comparing said three part formation at respective receivers. The system according to claim 1, wherein said transmission element is configured to use orthogonal encoding to provide a signal which is distinguishable from signals produced by at least one other transmission element; and/or wherein said transmission element is provided using an existing speaker element of said system and wherein said receiver unit is provided using an existing microphone element of said system. A method for small space positioning comprising: transmitting a modulated ultrasonic continuous wave from a fixed location, wherein the modulated ultrasonic continuous wave comprises a continuous ultrasonic carrier signal part and a predetermined ultrasonic base-band signal modulated onto said ultrasonic carrier signal part, said transmitting being into a range in which an object to be positioned may appear; receiving signals transmitted by the transmitting device and reflected by the object, said received signals comprising said modulated continuous ultrasonic wave; and determining a position of the object from analysis of the reflection from the object, wherein the analysis includes phase analysis, wherein determining comprises performing correlation between a said received signals and an expected modulated continuous wave.
CPC Classification	Radio Direction-Finding;Radio Navigation;Determining Distance Or Velocity By Use Of Radio Waves;Locating Or Presence-Detecting By Use Of The Reflection Or Reradiation Of Radio Waves;Analogous Arrangements Using Other Waves
Extended Family	008-287-704-157-332 002-171-336-863-491 102-057-728-878-496 091-712-312-679-371 055-384-837-894-992 137-917-968-243-163 011-963-556-359-619 067-982-031-152-864 039-083-342-339-63X 032-250-293-207-93X 000-589-956-468-666 107-443-086-148-818 174-084-913-916-98X 148-815-649-417-762
Patent ID	2930530
Inventor/Author	Altman Nathan Tsfati Yossi Agassy Meir
IPC	G01S13/32 G01S13/00 G01S15/00 G01S15/32
Status	Active
Simple Family	008-287-704-157-332 002-171-336-863-491 102-057-728-878-496 091-712-312-679-371 055-384-837-894-992 137-917-968-243-163 011-963-556-359-619 067-982-031-152-864 039-083-342-339-63X 032-250-293-207-93X 000-589-956-468-666 107-443-086-148-818 174-084-913-916-98X 148-815-649-417-762
CPC (with Group)	G01S13/003 G01S13/32 G01S15/003 G01S15/32 G01S7/52006 G01S13/82 G01S15/08
Issuing Authority	United States Patent and Trademark Office (USPTO)
Kind	Patent/Patent 1st level of publication/Inventor's certificate