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WO2008107374A1 - Dispositif et procédé de détermination de distance - Google Patents

Dispositif et procédé de détermination de distance Download PDF

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Publication number
WO2008107374A1
WO2008107374A1 PCT/EP2008/052462 EP2008052462W WO2008107374A1 WO 2008107374 A1 WO2008107374 A1 WO 2008107374A1 EP 2008052462 W EP2008052462 W EP 2008052462W WO 2008107374 A1 WO2008107374 A1 WO 2008107374A1
Authority
WO
WIPO (PCT)
Prior art keywords
radiation
receiver
reference object
distance
radiation pulses
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/EP2008/052462
Other languages
German (de)
English (en)
Inventor
Peter Mengel
Lutz Lohmann
Ludwig Listl
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens AG
Siemens Corp
Original Assignee
Siemens AG
Siemens Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Siemens AG, Siemens Corp filed Critical Siemens AG
Publication of WO2008107374A1 publication Critical patent/WO2008107374A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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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
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/497—Means for monitoring or calibrating
    • 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
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/88—Lidar systems specially adapted for specific applications
    • G01S17/89—Lidar systems specially adapted for specific applications for mapping or imaging
    • G01S17/894—3D imaging with simultaneous measurement of time-of-flight at a 2D array of receiver pixels, e.g. time-of-flight cameras or flash lidar

Definitions

  • the invention relates to a device for determining the distance with a transmitter emitting radiation pulses and a receiver, with which radiation pulses reflected by an object can be received, and with an evaluation unit connected to the receiver and the transmitter, which serves to determine the propagation time of the radiation pulses.
  • the invention further relates to a method for determining distance.
  • Such a device and such a method are known from DE 198 33 207 Al.
  • light pulses are transmitted to an object to be scanned by means of laser diodes.
  • the reflected light pulses from the object are detected by a CMOS sensor having a plurality of the incident light flux integrating sensor elements.
  • the individual object points are imaged by an optics arranged in front of the CMOS sensor onto the sensor elements.
  • the CMOS sensor allows random access to the individual sensor elements and allows integration times below one microsecond.
  • the integration time windows can be of different lengths. To determine the distance of an object point, the light pulse reflected by the object is integrated in an associated sensor element with different integration time windows.
  • the integration time windows have different lengths.
  • the transit time of the radiation pulses can then be determined from the values for the amount of light incident in the integration time windows. Since the speed of light is known, the distance of the object point results directly from the transit time.
  • the known device and the known method are also suitable, inter alia, for security surveillance or for access control. For safety reasons, it must be ensured that the individual pixels of the CMOS sensor are functional and provide the correct distance values. Otherwise, for example, there is a risk that a person who gets into the danger zone of a machine, is not detected and as a result, no safety shutdown of the machine.
  • the invention is therefore an object of the invention to provide a device and a method for determining distance, each of which provide the opportunity for functional self-monitoring.
  • a reference object is arranged in the radiation path of the radiation pulses, by which the radiation pulses are at least partially reflected back to the receiver. Since the spatial position of the reference object is known, the function of the receiver and of the transmitter can be checked on the basis of the radiation pulses reflected by the reference object. In particular, it can be determined whether a complete failure exists and whether appropriate distance values are determined. In this respect, a calibration of the device and the method is possible.
  • the reference object can be arranged outside the beam path which the radiation pulses travel to the object to be detected.
  • a deflection device is located in the beam path to the detecting object, by means of which the radiation pulses can be directed at least partially to the reference object.
  • the receiver is preferably an optical sensor having a plurality of detector elements with short-term integration. Using the detector elements, the
  • Radiation power of incident radiation within a variable integration time window are integrated into measured values for the incident during the integration time window radiant energy.
  • Such sensors allow the taking of distance images of objects.
  • the deflection device comprises a partially transmissive mirror, by means of which a part of the radiation power of the radiation pulses emitted by the transmitter to the reference object can be steered.
  • the reference object is preferably arranged at a distance which lies outside the range of the distance values in the monitoring area.
  • the function of the receiver can be monitored by taking pictures with different integration times.
  • the integration time windows can each be set so that the radiation pulses reflected back from the reference object and from the object to be detected fall into different integration time windows.
  • the integration time windows can be set such that the radiation pulses reflected by the reference object fall within integration time windows, the beginning of which coincides with the emission time of the radiation pulses, while integration time windows are provided for the radiation pulses reflected by the object whose beginning is a predetermined delay with respect to the emission time having the radiation pulses. In this case, no correction is required with respect to those components which are due to the laser pulses reflected by the reference object.
  • the integration time windows it is possible to always start the integration time windows at the same time interval as the emission time but to select the length of the integration time windows such that the radiation pulses reflected by the object fall only into the long integration time windows, whereas the radiation pulses reflected by the reference object both during the short as well as the long integration time window arrive.
  • the fraction of the reference object contained in the integration in the long integration time windows can be determined dynamically on the basis of the measurements with a short integration time window and corrected in the measurements with long integration time windows.
  • the radiation pulses reflected back from the object to be detected and from the reference object fall into the same integration time window.
  • the integration time windows are chosen to be so long or so placed that both the radiation pulses reflected back from the reference object and from the object to be detected are detected.
  • the components which are based on the radiation pulses reflected by the reference object must be detected and the measured values generated by the receiver must be adjusted by these components.
  • a delay unit can be provided by which the emission of the radiation pulses can be delayed by an adjustable period of time.
  • the delay of the emission timing of the radiation pulses has the same effect as changing the distance of an object to be detected.
  • the evaluation unit upon delaying the emission time, supplies a magnification of the distance of the object to be detected corresponding to the transit time. In this case, not only the function of the individual detector elements, but also the function of the downstream evaluation unit can be checked.
  • Figure 1 shows the structure of a distance sensor having a CMOS sensor with short-term integration
  • Figure 2 is a block diagram of the distance sensor of Figure 1;
  • Figure 3 is a timing diagram in which the timing of a measurement without time delay and a further measurement with time delay is entered;
  • Figure 4 shows the structure of a modified distance sensor
  • Figure 5 shows the structure of a further modified distance sensor.
  • Figure 1 shows a distance sensor 1, a transmitting and
  • Receiving unit 2 has.
  • the transmitting and receiving unit 2 transmits fan-shaped light pulses 3, which are reflected from an object 4 to be detected to the transmitting and receiving unit 2.
  • the light therefore follows an object beam path 6 between an object point 5 and the transmitting and receiving unit 2.
  • the object beam path 6 contains a beam splitter 7 which directs part of the emitted light along a reference beam path 8 to a reference object 9.
  • FIG. 2 shows a block diagram of the distance sensor 1 from FIG.
  • the transmitting and receiving unit 2 has a transmitter 10 which transmits the light pulses 3 to the object 4.
  • the transmitter 10 is preferably a laser that is capable of emitting laser pulses.
  • the transmitter 10 is a laser diode.
  • From the object 4 reflected light pulses 3 are received by a receiver 11.
  • the receiver 11 may comprise a field of detector elements 12 or, for example, comprise a single row of detector elements 12 arranged next to one another.
  • the detector elements 12 are each followed by a window unit 13, are set by the integration time window.
  • the window units 13 in each case act on an integrator 14.
  • the window unit 13 and the integrator 14 represent functional units that are accomplished on a CMOS sensor, for example, during an integration time window a charge storage device associated with a detector element 12 is discharged via a photodiode.
  • the integrator 14 is finally followed by an evaluation unit 15, which determines distance values from the measured values provided by the integrator 14 for the integrated-in quantity of light, and in this way creates a distance image of the object 4.
  • the distance image is created by a control unit
  • the transmitter 10 causes the transmitter 10 to emit a short light pulse.
  • an integration time window is opened in the receiver 11 via the window unit 13 and the luminous flux arriving during the integration time window is integrated.
  • the amount of light integrated during the integration time window can then, for example, be proportional to a voltage U output by the integrator 14.
  • Different integration times Ti and T 2 are used for the two measurements. From the voltage values Ui and U2 supplied by the integrator 14, the distance d of an object point 5 detected by a detector element 12 can be calculated according to the following equation:
  • c is the speed of light.
  • Typical values for the short integration times Ti are in the range of 10 to 60 nanoseconds.
  • the values for the long integration times T 2 are typically in the range between 60 and 120 nanoseconds.
  • the reference object 9 is arranged outside the object beam path 6.
  • the reference object 9 therefore does not affect the detection of the object 4, which is located in the monitoring area of the distance sensor 1.
  • the emitted by the transmitter 10 Light pulses 3 also reflected from the reference object 9 to the receiver 11.
  • the characteristic of the amount of light received voltage signal U ⁇ thus contains a portion U R, which is calledlutter- by the light returned from the reference object 9 light, and a further portion U M, which can be attributed to the light returned from the object 4 light.
  • the values U R can be determined for different integration times in a calibration process and stored as a reference value. The values U R can then be subtracted from the values U ⁇ and the actual object values U M determined in this way can be inserted into equation (1).
  • a mechanical closing device can be provided in the object beam path 6 after the jet 7, by which it is prevented that light is reflected by an object 4.
  • a mechanical closing device can be provided in the object beam path 6 after the jet 7, by which it is prevented that light is reflected by an object 4.
  • the separation between the signals originating from the reference object 9 and the object 4 to be detected can be achieved by selecting integration times which only lead to the detection of the light pulses 3 reflected by the reference object 9. This is possible if the difference in length between the object beam path 6 and the reference beam path 8 is so great that the light pulses 3 reflected by the reference object 9 arrive in front of the light pulses reflected back to the object 4 to be detected.
  • the reflectivity of the beam splitter 7 and the reflectivity of the reference object 9 are preferably selected such that the reference values U R are smaller than the lowest object values U M to be detected. This measure ensures that for all objects 4 to be detected, the light flux of the light reflected by the reference object 9 is smaller than the luminous flux that is reflected by the object 4 to be detected. Consequently, there is no danger that the signal that goes back to the object 4 to be detected in the Noise of the signal caused by the reflection at the reference object 9 is lost and therefore can no longer be detected.
  • the function of the detector elements 12 can be monitored. For even in the absence of the object 4 detect the detector elements 12, a light signal, which gives the reference value U R , which has been determined during the calibration for the respective integration time T. If, in the absence of the object 4 to be examined, the receiver 11 outputs a reference value for a specific detector element 12 which deviates from the reference value U R , it can be assumed that a malfunction of the respective detector element 12 is present.
  • the reference values U R must also be determined as a function of further operating parameters, such as the ambient temperature, in order to be able to monitor the function of the detector elements 12.
  • the monitoring can be carried out, for example, by constantly checking whether the values U ⁇ supplied by the integrator 14 are above the reference value U R determined during the calibration, which is to be used under the given operating parameters and the integration time used for the measurement. A failure of a detector element 12, in which the integrator 14 always delivers the value zero regardless of the amount of light incident, can be determined in this way.
  • Detector elements 12 which always deliver the value zero regardless of the incident luminous flux, can under certain circumstances also be detected by forming the difference of the measured values obtained in successive measurements with different integration times and checking whether the difference lies above a limit value which is determined by the difference of the reference values predetermined at the respective integration times. A failure of a detector element 12, which provides a constant output signal independently of the respective incidence of light, which is then integrated by the integrator 14, can not be detected in this way.
  • the reference values U R should be equal in this case to determine the reference distance d R of the reference object. 9 If the detector elements 12 function correctly, the reference distance d R should result from the measured values U T in this case.
  • FIG. 3 shows timing diagrams which show the course of a measurement 18 without delay and a subsequent measurement 19 with a delay.
  • a light pulse 20 is emitted with the duration T PW .
  • the light pulse 20 is reflected at the object 4, so that a reflected light pulse 21 arrives at the detector element 12 after a light propagation time T T0 F, which likewise has the duration T PW .
  • integration time windows are also opened.
  • an integration time window 22 with an integration time Ti is opened, so that the reflected light pulse 21 is integrated during the integration time Ti.
  • Ui i.
  • an integration time window 23 is opened with an integration time T2.
  • the reflected light pulse 21 is integrated into a measurement signal U 2 , i. From this a distance di is calculated, for which applies:
  • a light pulse 24 is emitted with the time delay T DELAY , which leads to a reflected light pulse 25, which is delayed by a period corresponding to the sum of T DELAY and T TOF .
  • T DELAY time delay
  • a measurement signal Ui, 2 and by integration during the integration time window 23 results in a measurement signal U2,2. From this a distance value d2 can be calculated, for which the following applies:
  • d 2 and di must therefore be equal to the distance traveled by the light during the time T DELAY . If something else results, this indicates that the detector element 12 is faulty or the downstream functional units, in particular the window unit 13, the integrator 14 or also the evaluation unit 15, operate incorrectly.
  • Object beam path 6 and the reference beam path 8 so large and the duration of the light pulses 3 can be chosen so short that the respective reflected back and received by the receiver 11 light pulses in time not exceeded
  • the reference distance d R can be determined in a first measurement with integration times, which merely lead to the integration of the light reflected at the reference object 9, and thus the function of the detector elements 12 can be checked.
  • the object distance d M can be determined, wherein the measured values obtained in the first measurement for the correction of the measured values can be used in the second measurement, if in the measured values of the second Measuring the
  • 35 amount of light that has been reflected from the reference object 9, and the obtained in the first measurement Measured value contains the amount of light contained in a light pulse reflected at the reference object 9.
  • FIG. 4 shows a further distance sensor 26 which has a reference object 27 which is located behind the object 4 to be detected in the beam direction.
  • the reference object 27 can be, for example, a wall, a floor or the ceiling of a room or any other area that limits access to a monitoring area.
  • the distance sensor 26 has the advantage that in the
  • FIG. 5 shows a further distance sensor 28 in which a partially transmissive mirror 29 is located in the object beam path 6. Since the light pulses 3 are partially reflected on the upper surface of the partially reflecting mirror 29, the partially transparent mirror 29 constitutes a reference object with which the function of the transmitting and receiving unit 2 can be monitored.
  • An advantage of the distance sensor 28 is that no further optical components are required.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Electromagnetism (AREA)
  • Optical Radar Systems And Details Thereof (AREA)

Abstract

L'invention concerne un capteur de distance (1) qui comprend une unité émettrice et réceptrice (2) servant à émettre des impulsions lumineuses (3) vers un objet (4) et à recevoir les impulsions lumineuses (3) renvoyées par l'objet (4). L'unité émettrice et réceptrice (2) offre la possibilité d'une intégration courte, ce qui permet de surveiller le temps de parcours des impulsions lumineuses (3). Pour l'auto-diagnostic de l'unité émettrice et réceptrice (2), on place dans la trajectoire de faisceau (6) de l'objet une unité de déviation (7) servant à diriger au moins partiellement les impulsions lumineuses (3) vers un objet de référence (9). L'unité émettrice et réceptrice (2) dispose en outre d'un dispositif de temporisation permettant de retarder l'émission d'une durée prédéfinie, de sorte que l'unité émettrice et réceptrice (2) peut détecter un accroissement de distance qui peut être comparé à des valeurs de référence prédéfinies.
PCT/EP2008/052462 2007-03-08 2008-02-29 Dispositif et procédé de détermination de distance Ceased WO2008107374A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102007011417A DE102007011417A1 (de) 2007-03-08 2007-03-08 Vorrichtung und Verfahren zur Entfernungsbestimmung
DE102007011417.8 2007-03-08

Publications (1)

Publication Number Publication Date
WO2008107374A1 true WO2008107374A1 (fr) 2008-09-12

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PCT/EP2008/052462 Ceased WO2008107374A1 (fr) 2007-03-08 2008-02-29 Dispositif et procédé de détermination de distance

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WO (1) WO2008107374A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102017125587A1 (de) 2017-11-02 2019-05-02 Pepperl + Fuchs Gmbh Optischer Sensor zum Nachweis von Objekten in einem Erfassungsbereich

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102741702B (zh) * 2009-12-21 2014-06-18 美萨影像股份公司 飞行时间相机系统的杂散光补偿方法和系统
US8964028B2 (en) 2009-12-21 2015-02-24 Mesa Imaging Ag Stray light compensation method and system for time of flight camera systems
CN117950078B (zh) * 2024-03-26 2024-09-06 深圳市柯莱顿光电科技有限公司 一种高速测量光幕及其控制方法

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19607345A1 (de) * 1996-02-27 1997-08-28 Sick Ag Laserabstandsermittlungsvorrichtung
DE19833207A1 (de) * 1998-07-23 2000-02-17 Siemens Ag Verfahren und Vorrichtung zur Aufnahme eines dreidimensionalen Abstandsbildes
WO2003040755A1 (fr) * 2001-11-08 2003-05-15 Siemens Aktiengesellschaft Reseau de lumiere laser destine a la mesure de distance
DE10249285A1 (de) * 2001-11-14 2003-05-22 Riegl Laser Measurement Sys Verfahren zur Entfernungsmessung mit einem opto-elektronischen Entfernungsmesser
WO2003056357A2 (fr) * 2001-12-22 2003-07-10 Conti Temic Microelectronic Gmbh Procede de mesure de distance

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JP2896782B2 (ja) * 1988-12-30 1999-05-31 株式会社トプコン パルス方式の光波距離計
DE4119797C2 (de) * 1991-06-15 1994-02-24 Leuze Electronic Gmbh & Co Einen Sender, einen Empfänger und eine Schaltungsanordnung zur Signalauswertung aufweisende Überwachungseinrichtung
DE10041182C2 (de) * 2000-08-23 2002-10-10 Leuze Lumiflex Gmbh & Co Optoelektronische Vorrichtung
DE10230397A1 (de) * 2002-07-05 2004-01-15 Sick Ag Laserabtastvorrichtung

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19607345A1 (de) * 1996-02-27 1997-08-28 Sick Ag Laserabstandsermittlungsvorrichtung
DE19833207A1 (de) * 1998-07-23 2000-02-17 Siemens Ag Verfahren und Vorrichtung zur Aufnahme eines dreidimensionalen Abstandsbildes
WO2003040755A1 (fr) * 2001-11-08 2003-05-15 Siemens Aktiengesellschaft Reseau de lumiere laser destine a la mesure de distance
DE10249285A1 (de) * 2001-11-14 2003-05-22 Riegl Laser Measurement Sys Verfahren zur Entfernungsmessung mit einem opto-elektronischen Entfernungsmesser
WO2003056357A2 (fr) * 2001-12-22 2003-07-10 Conti Temic Microelectronic Gmbh Procede de mesure de distance

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102017125587A1 (de) 2017-11-02 2019-05-02 Pepperl + Fuchs Gmbh Optischer Sensor zum Nachweis von Objekten in einem Erfassungsbereich

Also Published As

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