Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—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
  • G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
  • G01S15/88—Sonar systems specially adapted for specific applications
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—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
  • G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
  • G01S15/88—Sonar systems specially adapted for specific applications
  • G01S15/89—Sonar systems specially adapted for specific applications for mapping or imaging
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—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
  • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
  • G01S7/52—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00
  • G01S7/539—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section

Definitions

• the present invention relates to a method for determining measurement data of naked objects, such as people who may be dressed, by means of ultrasonic waves, wherein ultrasonic waves being transmitted to objects are reflected and the measurement data are determined on the basis of information contained in a received ultrasonic reflection pattern.
• the present invention furthermore relates to a device for determining measurement data of naked objects, such as people who may be dressed, by means of ultrasonic waves, which device comprises ultrasonic transmission means for transmitting ultrasonic waves to the object and receiving means for receiving a ultrasonic reflection pattern reflected from said object.
• a method and a device of this kind are known from JP-A- 52-3.436.
• Ultrasonic transmission means fitted with an ultrasonic wave oscillator for transmitting ultrasonic waves having a frequency of 10 KHz to the human body are used therein.
• a reflected ultrasonic interference pattern is deducted from the interfering waves reflected from the human body by means of arithmetic operations, whereby the distance to the human body is determined from the result on the basis of a phase difference change therein.
• One drawback of such a method and device is the fact that relatively complex arithmetic operations are required in order to arrive at the desired measuring result.
• the object of the invention is to provide an improved method and a simpler device, which make it possible to obtain measurement data of an object via less complex operations .
• the method according to the invention is characterized in that said measurement data are determined from runtime-related information contained in the received ultrasonic reflection pattern.
• the device according to the invention is characterized in that said device comprises data- processing means connected to said receiving means for determining said measurement data from runtime-related information contained in the received ultrasonic reflection pattern.
• the advantage of the method and device according to the invention is that information with regard to the distance between transmission means and receiving means can be derived directly from the runtime, given the velocity of the ultrasonic waves, without having to carry out relatively complex operations.
• a time window is used, within which the received ultrasonic reflection pattern is processed.
• time window means are connected between the receiving means and the data processing means for admitting the received ultrasonic reflection during a certain time span only.
• the transfer characteristic h(t) of some of the clothing of people is such that, due to multiple internal reflections in the material of the clothing, the response to an ultrasonic wave reflected therefrom is not momentaneous but spread over time.
• the transfer characteristic is time-dependent in that case, and in order to determine the effect of reflection from this type of clothing, all partial reflections must be integrated in time. There will be a convolution connection between cause and effect in that case.
• the received reflection pattern ⁇ effect / given the ultrasonic wave cause transmitted to the obj J ect must be determined in dependence on time t from the convolution operation: t
• the receiving means are arranged for transmitting ultrasonic, puls wave shaped signals, so that the convolution operation, when used, can be a "spike" convolution operation, as a result of which the received ultrasonic reflection pattern can be detected more easily and more unequivocally than would be possible with the transmission of for example a pulse train.
• Envelope detection of the received ultrasonic reflection pattern by means of an envelope detector in the receiving means is preferred, because of the simple decision software and hardware that is required, in order to enable a quick determination of measurement data.
• Figure 1 shows a schematic embodiment of a device according to the invention.
• Figure 2 shows a simulation model of the device of Figure 1.
• Figure 1 schematically shows a device 1 which is arranged for determining the measurements of objects 0, such as (usually clothed) persons, by means of ultrasonic waves without making contact with said objects.
• Ultrasonic waves having a frequency of up to 100 KHz are reflected well from a human object, whilst they are not reflected too much from clothing or absorbed by said clothing.
• Device 1 comprises transmission means 2, which contain one or more ultrasonic transducers and receiving sensors 3 , which may or may not be separated from said transmission means 2, which receive the ultrasonic reflection pattern.
• Said transducers are capable of scanning the object, for example in a line scan, so as to carry out measurements on the entire object or on that part of said object which generally determines for example the size of people's clothing.
• the transmission and receiving means 2 and 3 may be combined into one transducer, which is capable of transmitting and receiving successively in a so-called pulse echo mode.
• An envelope detector (not shown) is present in the receiving means 3, in which detection takes place on the basis of the maximum of the received ultrasonic reflection pattern.
• Transmission means 2 which transmit a pulsed ultrasonic signal appeared to provide sufficient resolving power, which lies around 3.3 mm with a pulse duration of 20 ⁇ sec, which results in an eventual measurement deviation which is acceptable for clothing sizes.
• the measurement data are determined, on the basis of transmission time-related information in the received ultrasonic reflection pattern, in data processing means 4 of the device 1 which are connected to the receiving means 3.
• the distance travelled can be determined on the basis of the time which passes between transmission and receipt, from which it is possible to determine the distance between transmission/receiving means 2/3 and the reflecting surface of the object in the plane in which measurements are being carried out.
• ⁇ cauae is a pulsed signal, this signal can be regarded in a mathematical sense as a distribution, and equation (1) leads to a "spike" convolution, wherein ⁇ effect (t) will be equal to h(t) in accordance with the screening characteristic of distributions. For some other types of clothing, wherein no multiple internal reflections occurred, the transfer characteristic h simply appeared to be momentaneous , however.
• the pulsed signal may for example be a triangular signal, which preferably has a total duration of about 3 - 30 ⁇ sec, more in particular 20 - 25 ⁇ sec, in order to realise an optimum resolving power. It has become apparent that it is possible to improve the signal-to- noise ratio considerably by using autocorrelation techniques, which are known per se, in the data processing means 4.
• Device 1 preferably comprises memory means 5 and a temperature gauge 6 connected to memory means 5.
• Figure 2 shows a simulation model of the device of Figure 1, wherein the transmission and receiving means 2 and 3 are arranged with transducers which each have a differentiating effect on the pulsed input signals supplied thereto.
• the effect is that the input signal supplied to means 4 in Figure 2 has been differentiated twice.

Landscapes

• Engineering & Computer Science (AREA)
• Radar, Positioning & Navigation (AREA)
• Remote Sensing (AREA)
• Physics & Mathematics (AREA)
• Computer Networks & Wireless Communication (AREA)
• General Physics & Mathematics (AREA)
• Acoustics & Sound (AREA)
• Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
• Length Measuring Devices Characterised By Use Of Acoustic Means (AREA)

Applications Claiming Priority (3)

Publications (1)

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• 1998
  • 1998-06-08 NL NL1009343A patent/NL1009343C2/nl not_active IP Right Cessation
• 1999
  • 1999-06-08 AU AU42936/99A patent/AU4293699A/en not_active Abandoned
  • 1999-06-08 EP EP99955543A patent/EP1086386A1/de not_active Ceased
  • 1999-06-08 WO PCT/NL1999/000356 patent/WO1999064889A1/en not_active Application Discontinuation

Non-Patent Citations (1)

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