DE102019212615A1 - Detector with parallax compensation - Google Patents

Abstract

Disclosed is a detector, in particular for a LIDAR device, for receiving beams reflected or backscattered on an object, having a plurality of radiation-sensitive exposure areas for temporarily recording image information, having at least one readout register for receiving the image information and for transporting the received image information and having at least one readout unit for reading out the image information transported via the readout register, wherein a readout direction of the readout register is opposite to a parallax shift of the reflected or backscattered rays, which occurs when the distance between the detector and the object increases. A LIDAR device and a control device are also disclosed.

Description

The invention relates to a detector, in particular for a LIDAR device, for receiving beams reflected or backscattered from an object, having a plurality of radiation-sensitive exposure areas for temporarily recording image information, having at least one readout register for receiving the image information and for transporting the received image information . The invention also relates to a LIDAR device and a control unit.

State of the art

LIDAR (light detection and ranging) devices are known which generate beams with the aid of a transmission unit and emit them in the direction of a scanning area. The beams reflected in the scanning area can then be detected and evaluated by a receiving unit.

To cover large horizontal detection angles, for example between 150 ° and 360 °, only mechanical LIDAR devices designed as laser scanners are known today. If only one deflecting mirror is used to deflect beams, the maximum horizontal scanning range is limited to approx. 150 °. For larger detection ranges of up to 360 °, mainly biaxial LIDAR devices are used, in which all electro-optical components are located on a motor-driven turntable or rotor.

Such biaxial LIDAR devices have a parallax shift due to the distance between the transmitting unit and the receiving unit. The problem with the parallax shift is that the detector of the LIDAR device cannot detect any received rays in the close range or that the image information determined becomes unusable because the transit time is too short and overlaps with subsequent rays.

Disclosure of the invention

The object on which the invention is based can be seen in proposing a detector and a LIDAR device which can also reliably determine image information at close range.

This object is achieved by means of the respective subject matter of the independent claims. Advantageous embodiments of the invention are the subject matter of the dependent subclaims.

According to one aspect of the invention, a detector, in particular for a LIDAR device, is provided for receiving rays reflected or backscattered from an object. The detector has a plurality of radiation-sensitive exposure areas for temporarily recording image information and at least one readout register for receiving the image information and for transporting the received image information. Furthermore, the detector has at least one readout unit for reading out the image information transported via the readout register, with a readout direction of the readout register opposing a parallax shift of the reflected or backscattered rays, which occurs when the distance between the detector and the object increases.

According to a further aspect of the invention, a LIDAR device for scanning scan areas is provided. The LIDAR device has at least one transmitting unit for generating and emitting generated beams into a scanning area and at least one receiving unit with a detector according to the invention.

According to a further aspect of the invention, a control device is provided which is set up to evaluate image information of a detector according to the invention and / or to control radiation-sensitive exposure areas of the detector. In particular, the control device can be configured to control and read out the detector and to operate the LIDAR device. The control device can be connected to a readout unit of the detector or can be integrated into the readout unit.

The detector can preferably be designed as a CCD chip and can be used in a technically simple and robust configuration of a LIDAR device. Such a LIDAR device can be used, for example, for automated driving, aviation applications, measuring methods, robotics applications and the like.

The LIDAR device can for example be a horizontal biaxial LIDAR device in which the transmitting unit is arranged parallel to the receiving unit on a turntable.

The parallax shift has the effect that the rays or spots arriving from close targets impinge on the radiation-sensitive exposure areas of the detector closer to the readout unit. By designing the readout direction of the readout register of the detector in the opposite direction of the parallax shift, an undesired superimposition of image information by subsequent received rays can be avoided and thus a clear distance measurement from nearby targets can be achieved.

The use of a detector according to the invention in a LIDAR device enables a horizontal design in which the parallax shift can be compensated or used. As a result, the LIDAR device can have a low height with a constant diameter. Due to the design of the detector, distance measurements of objects in the vicinity of the LIDAR device can also be made possible.

According to one exemplary embodiment, the at least one readout register is designed in the form of lines and can be connected at least on one side to exposure areas of the detector arranged in lines for reading out image information. The readout register has a large number of pixels, the exposure areas being designed in the form of pixels and at least two, preferably at least four, pixels of the readout register being arranged between two exposure areas. With an increasing number of pixels in the readout register, the image information from the pixels of the exposure areas can be temporarily stored in the readout register. The readout registers are preferably designed in the form of lines and form a row of pixels which transmit the image information from the exposure areas of the detector pixel by pixel to the readout unit. With an increased number of pixels in the respective readout registers, a higher temporal resolution can be implemented for the recording and transmission of the image information.

According to a further exemplary embodiment, every second radiation-sensitive exposure area can be activated in order to receive image information. As a result, the number of pixels in the readout register between each exposure area can be increased in a technically particularly simple manner. The activated exposure areas and the deactivated exposure areas can preferably be actuated alternately by the control device in order to collect image information.

According to a further exemplary embodiment, a distance to the object can be determined by the readout unit on the basis of a number and / or a position of the exposure areas exposed by the beams. The spot reflected or backscattered from the scanning area on an object is imaged with a defined area on the exposure areas of the detector. As the distance between the object and the LIDAR device increases, the area and thus the size of the spot which is projected onto the exposure areas decreases. With an increasing number of exposed exposure areas, conclusions can be drawn from a larger area of the spot and thus from a smaller distance to the object. In this way, a distance to the object can be derived from the size of the spot received on the exposure areas. This can be done using a formula or a calibration table.

According to a further embodiment, the detector is designed to be elongated in the direction of the parallax shift. As a result, a measuring range of the detector and thus also of the LIDAR device can be enlarged in such a way that, despite a parallax shift, the beams backscattered or reflected from the scanning range are received by the detector. The receiving unit with the detector is preferably arranged relative to the transmitting unit in such a way that the parallax shift is opposite to the readout direction of the readout register. For this purpose, the detector is designed to be extended or offset in a direction facing away from the transmitter unit.

According to a further embodiment, the exposure information received by the readout unit can be assigned to the exposure areas at which this exposure information was generated, the exposure information being able to be received by the readout unit in a spatially resolved manner. As a result of this measure, in addition to the temporal resolution of the received image information, a spatial resolution can be implemented which can be used as an alternative or in addition to the temporal resolution for a distance measurement. In particular, as a result of the parallax shift, the detection location can vary along the detector as a function of the distance. For example, on the basis of an initial calibration, the detection location of received beams along the detector can provide information about the distance of the object from the detector.

According to a further exemplary embodiment, at least one exposure area of the detector can be activated and deactivated as a function of time, with a multiplicity of exposure areas being activated and deactivated successively. A combination of temporal activation of the exposure areas or the CCD pixels and a specially provided structure of the readout register can achieve both temporal and spatial resolution of the image information and thus distance measurement can also be made in the near field.

According to a further exemplary embodiment, the exposure areas of the detector can be activated and deactivated in a time-constant or variable pattern. For this purpose, a sufficient number of pixels of the shift register or the readout register can be provided between two adjacent, radiation-sensitive exposure areas. By a suitable activation of the radiation-sensitive Exposure areas in a pattern can increase the number of pixels in the readout register between two active exposure areas and thus increase the storage capacity of image information in the readout register during a readout process to the readout unit. Assuming, for example, four pixels of the readout register between two adjacent exposure areas and only activating every second exposure area, the shift frequency of e.g. 4ns results in a total time of 32ns, which is available to be able to record a clear signal based on the image information.

• 1 eine schematische Darstellung einer LIDAR-Vorrichtung gemäß einem Ausführungsbeispiel,
• 2 eine Draufsicht auf die LIDAR-Vorrichtung aus 1,
• 3 ein schematisches Diagramm zum Veranschaulichen eines Zusammenhangs zwischen einer Detektionsposition, einer Time-of-Flight und einer auf dem Detektor projizierten Fläche eines Spots,
• 4 eine Schnittdarstellung von zeilenförmigen Belichtungsbereichen und Ausleseregistern bei einer Entfernung zu einem Objekt von einem Meter,
• 5 eine Schnittdarstellung von zeilenförmigen Belichtungsbereichen und Ausleseregistern aus der 4 bei einer Entfernung zu einem Objekt von fünf Metern,
• 6 ein schematisches Muster für eine Aktivierung von zeilenförmig angeordneten Belichtungsbereichen und
• 7 ein schematisches Muster für eine Aktivierung von flächig angeordneten Belichtungsbereichen.

In the following, preferred exemplary embodiments of the invention are explained in more detail with the aid of greatly simplified schematic representations. Show here

• 1 a schematic representation of a LIDAR device according to an embodiment,
• 2 a top view of the lidar device 1 ,
• 3 a schematic diagram to illustrate a relationship between a detection position, a time-of-flight and an area of a spot projected on the detector,
• 4th a sectional view of line-shaped exposure areas and readout registers at a distance of one meter to an object,
• 5 a sectional view of line-shaped exposure areas and readout registers from FIG 4th at a distance of five meters to an object,
• 6th a schematic pattern for activating exposure areas arranged in lines and
• 7th a schematic pattern for an activation of areally arranged exposure areas.

The 1 shows a schematic representation of a LIDAR device 1 according to an embodiment. The LIDAR device 1 has a transmitter unit 2 and a receiving unit 4th on.

The transmitter unit 2 is used to generate and emit rays 6th along a scanning area A. For example, the beams generated 6th be designed as laser beams. The transmitter unit 2 one or more laser emitters 3 on. The transmitter unit 2 can the rays 6th generate and emit with a defined pulse frequency. This can be done by a control unit 8th coordinated and initiated.

The receiving unit 4th has a detector 10 and a receiving optics 12 on. The one in the direction of the receiving unit 4th from the scanning area A reflected or backscattered rays 14th are from the receiving optics 12 received and into the receiving unit 4th steered.

The detector 10 can be designed as an area detector, such as a CCD. The detector 10 has a large number of radiation-sensitive exposure areas 11 which can generate electrical signals or image information in the form of measurement data from incoming beams. The detector 10 is such with the control unit 8th coupled that a location-dependent evaluation of the measurement data of the detector 10 is possible. In particular, the measurement data can correspond to the radiation-sensitive exposure areas 11 in which the respective measurement data were generated by incident rays.

The control unit 8th can preferably be used as an evaluation unit for evaluating the measurement data of the detector 10 and for activating or deactivating radiation-sensitive exposure areas 11 be executed.

The 2 Figure 13 shows a top view of the LIDAR device 1 out 1 . The transmitter unit 2 and the receiving unit 4th are on a rotor 16 arranged and can thus be pivoted or rotated through 360 ° along an axis of rotation R. This allows a horizontal biaxial arrangement of the LIDAR device 1 will be realized.

The detector 10 the receiving unit 4th has a large number of radiation-sensitive exposure areas 11 which are designed as pixels. The pixels 11 are arranged in lines to form an area. For receiving and evaluating rays 14th from a close range of the LIDAR device 1 is the detector 10 in readout direction X of the radiation-sensitive exposure areas 11 by an extension section 18th extended.

From the radiation-sensitive exposure areas 11 determined image information 26th are read in lines by a readout unit 20th read out and then sent to the control unit 8th forwarded. The control unit 8th can use the image information available as measurement data 26th use for further evaluation.

In addition, there is a parallax shift P of the reflected or backscattered rays 14th shown schematically which with an increase in the distance between the detector 10 and an object O occurs in the scanning area A at which the generated rays 6th be reflected or backscattered.

In the 3 FIG. 11 is a schematic diagram to illustrate a relationship between a detection position along the readout direction X, a flight duration t of the beams 14th and one on the detector 10 projected area F of a spot or the rays 14th shown.

The relationship shown is due to the horizontal offset of the transmitter unit 2 and the receiving unit 4th . Here, the position and the spot size F of the signal changes depending on the distance to an object O in scanning area A or as a function of the flight duration t. In a CCD-based system, this requires the detector 10 be designed accordingly in order to be able to record a signal at all in the close range and not to make this unusable by subsequent signals. To this end, the detector 10 the extension section 18th on and a readout direction X of the radiation-sensitive exposure areas 11 , which from the transmitter unit 2 is directed away.

The diagram shown shows the detector as an example 10 projected areas F at a distance of a scanned object O in the scanning range A of one, two, four, ten and twenty meters. The corresponding curve can be determined using a calibration and in the control unit 8th be stored, for example, to implement a distance measurement based on a determined area F.

In the 4th Fig. 3 is a cross-sectional view of line-shaped exposure areas 11 and readout registers 22nd at a distance to an object O shown in scanning area A of one meter. The 5 shows a sectional view of line-shaped exposure areas 11 and readout registers 22nd from the 4th at a distance to an object O in the scanning range A of five meters. The two figures show, in particular, the variation of the detection position along the X axis and the area F as a function of a flight duration t or the distance to a point at which the generated beams 6th were reflected or backscattered in the scanning area A, clarified.

As a basis for the design of the detector 10 is a sufficient number of pixels 23 of the readout register 22nd between two neighboring pixels 24 , 25th the radiation-sensitive exposure areas 11 intended. The pixels 24 , 25th the radiation-sensitive exposure areas 11 are here in a pattern by the control unit 8th activated and deactivated. According to the embodiment, every other pixel 24 as activated and the remaining pixels 25th set as disabled. The pixels 24 , 25th are alternately activated and deactivated after a defined period of time.

This means that there are between two pixels 24 , 25th the radiation-sensitive exposure areas 11 for example four pixels 23 of the readout register 22nd intended. An exemplary shift frequency of 4ns results in a total time of 32ns, which is available to be able to record a clear signal.

This time of 32ns already corresponds to the distance covered by the beams 6th , 14th to an object O at a distance of 4.8m. At this distance, the parallax effect is reduced to such an extent that image information is superimposed 26th is avoided. This allows the signal or the incoming rays 14th can be recorded not only time-resolved but also spatially resolved. This is a prerequisite for an accurate distance measurement to be carried out for the near field. A second requirement for this is that the readout register 22nd is operated against the parallax shift in readout direction X. Because during the 32ns each pixel 23 of the readout register 22nd the signal of an illuminated, activated pixel only once 24 has recorded, a clear identification of the travel time or the flight duration t is possible. In addition, by evaluating all pixels 24 , 25th the local resolution of the signal can be evaluated, which enables additional information regarding the measured distance.

The 6th shows a schematic pattern for an activation of exposure areas arranged in lines 11 . In the 7th is a schematic pattern for an activation of areally arranged exposure areas 11 shown.

With the appropriate selection of an activation pattern, a clear and thus calibratable signal in the form of image information can be generated in an entire near and far range 26th be measured. This pattern depends on the size of the parallax, the optics of the transmitter unit 2 and the receiving unit 4th as well as the pixel size of the detector 10 from.

In the 6th and 7th are the pixels 23 the readout register 22nd at times t1-t8 shown at which the respective exposure areas 11 activated or deactivated. You can do this at different times t1-t8 Image information 26th into the pixels 23 the readout register 22nd transmitted and to the readout unit 20th be transported.

Claims (10)

Detector (10), in particular for a LIDAR device (1), for receiving beams (14) reflected or backscattered on an object (O), having a plurality of radiation-sensitive exposure areas (11) for temporary purposes Recording of image information (26), having at least one readout register (22) for receiving the image information (26) and for transporting the received image information (26) and having at least one readout unit (20) for reading out the image information transported via the readout register (22) ( 26), characterized in that a read-out direction (X) of the read-out register (22) is opposite to a parallax shift (P) of the reflected or backscattered beams (14), which occurs when the distance between the detector (10) and the object ( O) occurs. Detector after Claim 1 , wherein the at least one readout register (22) is shaped like a line and can be connected at least on one side to exposure areas (11) of the detector (10) arranged in lines for reading out image information (26), the readout register (22) having a plurality of pixels (23) , the exposure areas (11) are pixel-shaped and at least two, preferably at least four, pixels (23) of the readout register (22) are arranged between two exposure areas (11). Detector after Claim 1 or 2 wherein every second radiation-sensitive exposure area (11) can be activated for receiving image information (26). Detector after one of the Claims 1 to 3 , a distance of the object (O) through the readout unit (20) and / or a control unit (8) that can be connected to the readout unit (20) based on a number and / or a position of the exposure areas (11) exposed by the beams (14) can be determined. Detector after one of the Claims 1 to 4th , the detector (10) being designed to be elongated in the direction of the parallax shift (P). Detector after one of the Claims 1 to 5 wherein the exposure information (26) received by the readout unit (20) can be assigned to exposure areas (11) at which this exposure information (26) was generated, the exposure information (26) being able to be received by the readout unit (20) in a spatially resolved manner. Detector after one of the Claims 1 to 6th , wherein at least one exposure area (11, 24, 25) of the detector (10) can be activated and deactivated as a function of time, a plurality of exposure areas (11, 24, 25) being activated and deactivated successively. Detector after one of the Claims 1 to 7th wherein the exposure areas (11, 24, 25) of the detector (10) can be activated and deactivated in a time-constant or variable pattern. LIDAR device (1) for scanning scanning areas (A), having at least one transmitting unit (2) for generating and emitting generated beams (6) into a scanning area (A) and having at least one receiving unit (4) with a detector (10) ) according to one of the preceding claims. Control device (8) which is set up to receive image information (26) of a detector (10) according to one of the Claims 1 to 8th to evaluate and / or to control radiation-sensitive exposure areas (11, 24, 25) of the detector (10).

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