METHOD AND DEVICE FOR OPTICAL DISTANCE MEASUREMENT

Description

Technical field

[0001] The invention relates to a method and a device for optical distance measurement. State of the art

[0002] Optical distance measurements, particularly for use in driverless vehicle navigation, are well known in the art. They are based on the time-of-flight (ToF) principle. A scanning sensor, particularly a LIDAR (short for "light detection and ranging") sensor, is used for the measurement. It periodically emits measurement pulses that are reflected by objects. The reflected measurement pulses are then detected. By determining the travel time of the measurement pulses from the sensor to the objects and back, the distance to these objects can be determined using the speed of light.

[0003] The principle of ToF measurements is limited by the fact that measurement pulses must be sent at a certain distance from each other in order to avoid so-called aliasing effects.

[0004] In principle, ToF measurements wait twice the propagation time until the end of a measuring range, until a previously transmitted measuring pulse has theoretically been received again after reflection. If this time is not waited for, a clear assignment of the received measuring pulses is not possible, since the time of transmission is uncertain. This limits the possibility of ToF measurements, since the propagation time of the pulse, i.e. the time it takes for the measuring pulse to reach a sensor again, cannot be accelerated. Therefore, in order to scan a large distance range, after initiating a measuring pulse, twice the propagation time to the furthest possible object must be waited until another measuring pulse can be emitted.

[0005] Furthermore, the emitted energy is an essential parameter for the maximum detection range to ensure that reflections from distant objects can still be detected.

[0006] Overall, increasing the detection probability with the current technology is fundamentally only possible with an increased time budget or increased energy. However, for eye safety reasons, the lowest possible peak power of the transmitted pulses is desirable. A low time budget is also desirable, as only then can measurement results be available promptly and used for time-critical applications, such as driver assistance.

[0007] DE 10 2016 011 299 A1, for example, describes the use of coded pulse sequences to avoid the ambiguities described above. However, the detection range also suffers with pulse sequences, since measurement pulses are not detected, especially at long distances, and recognition of the sequence is not possible.

[0008] WO 2012 / 135874 A1 discloses a method for measuring the distance of environmental targets by measuring the time of flight of pulses reflected therefrom.

[0009] DE 10 2017 208 704 A1 discloses a device for distance measurement comprising a transmitting device, a receiving device and a random generator device. Description of the invention: task, solution, advantages

[0010] The present invention is based on the object of improving a method and a device for distance measurement in such a way that the maximum detection range can be increased while maintaining the same time budget, the peak power of measuring pulses can be reduced while maintaining the same detection probability, and interference by internal or external pulses can be avoided.

[0011] The above-mentioned object is achieved by a method for optical distance measurement, in which, within a first measurement interval, a first plurality of measurement pulses are transmitted by a transmitting element of a transmitting unit at first transmission times, and within a second measurement interval, a second plurality of measurement pulses are transmitted by a transmitting element of a transmitting unit at second transmission times. Reflected measurement pulses are received at reception times by a receiving element of a receiving unit assigned to the transmitting element.

[0012] The method comprises determining a first set of propagation times for each received measurement pulse. The propagation times are determined using the first transmission times. The times determined in this way form the propagation times of the first set. According to the invention, for this purpose, each first transmission time is subtracted from the reception time of each received measurement pulse. A second set of propagation times is determined in the same way. In detail, the method comprises determining a second set of propagation times for each received measurement pulse using the second transmission times, specifically according to the invention by subtracting each second transmission time from the reception time of the respective received measurement pulse. Adjacent measurement intervals immediately follow one another in time.

[0013] The transmission times are preferably determined in relation to the start time of the respective measurement interval. The reception times are preferably determined in relation to the start time of the first measurement interval.

[0014] This means that all combinations of reception times and transmission times are taken into account. Transmission times that are later in time are also subtracted from reception times. This is the case, for example, if the reception time (relative to the start time of the first measurement interval) is greater than the transmission time (relative to the start time of the second measurement interval), even though the transmission time is later than the reception time. Nevertheless, the correct propagation time can be determined easily and effectively. Difficult and time-consuming comparisons of transmitted and received pulse sequences can thus be eliminated.

[0015] The method further comprises creating at least one histogram for the receiving element and entering the first set and / or the second set of runtimes into the histogram. In other words, at least one, in particular exactly one, histogram can be created for each measurement interval. Furthermore, measurement intervals can be entered into a common histogram. Furthermore, individually created histograms can be added to form a common histogram.

[0016] In particular, the present method is carried out by means of a transmitting unit comprising a plurality of transmitting elements and a receiving unit comprising a plurality of receiving elements. In particular, each transmitting element of the transmitting unit is assigned to a defined sub-area of ​​the measuring range, in other words, a spatial element of the measuring range. The same applies to the receiving unit. Each receiving element is also assigned a sub-area of ​​the measuring range. This results in a unique assignment between transmitting elements of the transmitting unit and receiving elements of the receiving unit. From the fact which receiving element thus receives a measuring pulse, a conclusion can be drawn about the position of the reflecting object at which the measuring pulse was reflected.

[0017] A reflected measurement pulse is a measurement pulse that was previously transmitted, but whose direction of propagation has changed due to the reflection from an object. The reflected measurement pulse can therefore be understood as an echo of the transmitted measurement pulse. Specifically, the method determines the travel time of the measurement pulses to the objects from which they were reflected. From this, the distance traveled by the respective measurement pulse to the object is determined using the speed of light.

[0018] Optical distance measurement is characterized by the fact that distances are determined using optical signals, in this case optical measurement pulses. The term "distance" refers to a distance. The distance traveled by the measurement pulse is the distance between the transmitting element that emitted the measurement pulse and the object that reflected it, plus the distance between the object and the receiving element that received the corresponding reflected measurement pulse. In particular, the method includes taking into account the exact position of the transmitting element and the receiving element, especially in relation to each other.Since the at least one object is typically a three-dimensional object, meaning that some areas of the object may be closer and others farther away, the term "distance to the object" refers to the distance to at least one point on the object, namely the point where the measuring pulse struck and was reflected. The transit time is the time it took the measuring pulse to travel the previously described distance.

[0019] The method is preferably used for distance measurement for application in driverless navigation or driver assistance systems of vehicles.

[0020] A measuring pulse is, in particular, an electromagnetic signal, particularly an optical signal. This signal preferably has a wavelength that is not within the range visible to the human eye. For safety reasons, invisible infrared is preferably used. Since the measuring pulse is an electromagnetic signal and the speed of the measuring pulse is therefore known, the distance traveled by the measuring pulse can be determined from the transit time of the measuring pulse using the speed of light.

[0021] When determining initial sets of propagation times, the received measurement pulses are evaluated in a very special way. By relating the reception times to all possible transmission times, multiple compensation takes place. Compensation is defined as a shift in the reception time of a received measurement pulse in the histogram based on a transmission time. In other words, each measurement pulse is compensated for every plausible or possible transmission time, with all results being entered into a histogram.

[0022] In this way, exactly one "correct entry" results for each measurement pulse, since the reception time was compensated with the correct transmission time. However, a large number of "incorrect entries" also results, since the reception time of a measurement pulse was compensated with "incorrect transmission times," i.e., transmission times of other measurement pulses. However, because a large number of measurement pulses were transmitted within a measurement range, it is not known which of these transmission times is correct. This is solved by the present method. It increases the entries in the histogram, with the entries of the "correct compensations" overlapping at only one position. All further delays resulting from compensation with "incorrect transmission times" also appear as interference symmetrically around this correct position in the histogram.The first and second sets of propagation times for a measuring pulse thus include all possible propagation times, whereby only one of these is "correct" because the correct transmission time was the basis for the determination.

[0023] This allows the correct distance to an object from which the measurement pulses were reflected to be determined. In particular, the method involves determining a distance based on the histogram, which can be assigned to the receiving element. This is done primarily by determining the time of flight for which the most entries are present. In particular, this corresponds to the "correct" time of flight, from which the distance can be easily determined by taking the speed of light into account.

[0024] Since a large number of measurement pulses are emitted, but corresponding ambiguities can be clearly resolved, the maximum detection range can be increased while maintaining the same time budget and / or the peak power of the measurement pulses can be reduced while also maintaining the same detection probability. In particular, increasing the number of measurement pulses per unit time increases the detection probability and the signal-to-noise ratio. The present invention thus solves the time budget limitations (based, for example, on the image sequence requirements for capturing a scene with motion) and the energy limitations (based on eye safety).

[0025] The multitude of measurement pulses emitted within a measurement interval can also be understood as a pulse sequence. This term refers specifically to a temporal sequence of measurement pulses determined by the number of measurement pulses, their pulse lengths, and the temporal pulse intervals between the measurement pulses. However, in the present method, even though the measurement pulses can be understood as a pulse sequence, the entire pulse sequence is not assigned a single transit time, as is known from the prior art. Instead, each measurement pulse is evaluated individually, and a correct and a plurality of "incorrect transit times" are assigned to the measurement pulse.

[0026] In particular, the first measurement interval and the second measurement interval are not identical. Preferably, they each have a start time and an end time, with the start times and / or the end times preferably not coinciding.

[0027] The first and / or second measuring intervals preferably have a length that is equal to one or two times the length of the measuring range. The measuring intervals are, in particular, of equal length, with the length of the measuring interval being selected such that it corresponds to the time required for a measuring pulse to completely traverse the measuring range once (i.e., to the end of the measuring range) or twice (i.e., to the end of the measuring range and back again).

[0028] The length of the measurement interval thus corresponds to a transmission window in which measurement pulses are transmitted. The detection interval, in which measurement pulses can be received, can begin simultaneously with the corresponding, preferably the first, measurement interval.

[0029] Furthermore, the length of the detection interval can be double or quadruple the length of the measurement interval. The method particularly includes memorizing the transmission times of the measurement intervals so that the reception times can be related to them.

[0030] Each measurement interval can be assigned a detection interval. In this case, the detection range overlaps with the subsequent, particularly second, measurement interval or encompasses it completely.

[0031] Furthermore, a common detection interval can be assigned to several measurement intervals, in particular the first and second measurement intervals. The detection interval then begins with the start time of the first measurement interval and preferably ends after the duration of another measurement interval has elapsed after the end time of the second or last measurement interval.

[0032] The first and second measurement intervals can overlap. The start time of the second measurement interval thus occurs before the end time of the first measurement interval. In particular, the first measurement interval and the second measurement interval follow one another directly.

[0033] Furthermore, the first measurement interval and the second measurement interval can be spaced apart in time, meaning they do not directly follow one another. The start time of the second measurement interval thus lies after the end time of the first measurement interval, although the detection interval and the second measurement interval nevertheless at least overlap. In particular, the detection range always encompasses the second measurement interval. This means that even though measurement pulses from one measurement interval are still in transit and can still be detected due to the detection interval being preferably twice as long, a new measurement interval with the transmission of new measurement pulses can already follow. The pulse sequences of adjacent measurement pulses are thus "on air" simultaneously.

[0034] Preferably, the method comprises carrying out further measurements in further measuring intervals, with adjacent measuring intervals immediately following one another in time.

[0035] In particular, the histogram shows the length of the measurement intervals. In particular, only runtimes greater than 0 and less than the length of the measurement interval are entered into the histogram.

[0036] In particular, an equal number of measuring pulses can be emitted in the measuring intervals, for example a number N. Since both the measuring pulses emitted within this measuring interval and the measuring pulses emitted within the previous measuring interval can be received within a measuring interval, 0 to 2 N measuring pulses can be received, where N stands for the number of measuring pulses emitted per measuring interval.

[0037] Furthermore, adjacent measurement pulses of the plurality of measurement pulses emitted within a measurement interval can preferably be randomly spaced from one another. In particular, the emission times of the measurement pulses of the first measurement interval and the second measurement interval or of adjacent measurement intervals can differ. Due to the randomness of the positions of individual measurement pulses within a sequence, the evaluation and thus the determination of the distance within the sequences is robust against interference from its own neighboring sequences as well as external interference, since these are distributed across the histogram.

[0038] Also, due to the random transmission times, the incorrect entries in the histogram are randomly distributed, so that the correct entries that overlap stand out clearly.

[0039] Furthermore, the plurality of measuring pulses emitted within the first or second measuring interval can preferably be coded. At least two measuring pulses emitted in the first measuring interval or in the second measuring interval differ, in particular, by their pulse shape. In particular, each measuring pulse can differ from every other measuring pulse, but only two different coding states can also be possible. Furthermore, measuring pulses can differ by their pulse length. A coding state can thus be understood as a pulse shape and / or a pulse length.

[0040] Based on the states, as described above, a histogram can be created for each coding state. The method for this can include remembering the coding states of the transmitted measurement pulses and determining the coding states of the received measurement pulses. Determining a first set of propagation times for each received measurement pulse only considers the transmission times of the measurement pulses with the same coding state. The same applies to the second set of propagation times. A separate histogram is then created for each coding state, into which the propagation times of the correspondingly coded received measurement pulses are entered. This reduces the number of entries in the respective histograms, since measurement pulses can already be differentiated based on their coding states. The measurement range can preferably be divided into at least one short section, one mid section, and one far section.The short section is the spatially closest section, preferably directly adjacent to a device for carrying out the method, while the far section represents the rearmost section, in other words a section at the end of the measuring range. The mid section lies in between. For example, the first third of the measuring range can represent the short section, the middle third the mid section, and the last third the far section. In particular, each receiving element has an imaging region, in particular a photosensitive surface, which can be divided into different regions, in particular depending on the section of the measuring range in which the measuring pulse was reflected. Reflected measuring pulses from the short section, the mid section, and the far section are thus received in different regions of a receiving element.

[0041] In other words, there is a shift in the imaging area where a pulse occurs on a receiving element, depending on the distance of the object from which the measurement pulse was reflected. This shift results from a parallax error.

[0042] A short interval of the measurement interval and a short range of the receiving element can be assigned to the short section, a mid interval of the measurement interval and a mid range of the receiving element can be assigned to the mid section, and a far interval of the measurement interval and a far range of the receiving element can be assigned to the far section. This corresponds to the time segments of the measurement interval into which the corresponding transit times fall in the differently distant sections of the measurement interval. For example, the first third of the measurement interval can represent the short interval, the middle third the mid interval, and the last third the far interval.

[0043] The different areas of the imaging range of the receiving element can be controlled separately. Preferably, the short range of the receiving element can be designed to be less sensitive than the mid-range and far-range of the receiving element. This serves to prevent "blinding" of the short range, for example, when a highly reflective object is located very close.

[0044] The short range, mid range, and far range of the receiving element can be controlled based on the short interval, mid interval, and far interval of the first measurement interval. Specifically, the different ranges of the receiving element are activated precisely when the measurement is within the corresponding short interval, mid interval, or far interval. Specifically, the short range is activated during the short interval, the mid range during the mid interval, and the far range during the far interval. Outside of these intervals, the corresponding ranges are deactivated.

[0045] In particular, control is based solely on the first measurement interval, with the transmission of measurement pulses during the second measurement interval having no influence on the activation of the zones. However, it may be advantageous to deactivate all zones of the receiving element during the corresponding short interval of the second measurement interval to avoid blinding.

[0046] In particular, the second measurement interval can be followed by a third measurement interval, based on which the regions are controlled. Thus, every second measurement interval preferably controls the activation or deactivation of the regions of the receiving element, while the intervening measurement intervals do not influence the control except for the deactivation of all regions during the associated short interval.

[0047] In particular, the method performs the above-mentioned steps for multiple transmitting elements of a transmitting unit and corresponding receiving elements of a receiving unit, in particular all transmitting elements and receiving elements. In other words, corresponding measurement pulses are emitted by multiple transmitting elements within a measurement interval at transmission times and received by corresponding receiving elements at reception times, wherein a first set and a second set of transit times are then determined for the measurement pulses received by each receiving element. A corresponding histogram is created for each receiving element.

[0048] In a further aspect, the invention relates to a device for carrying out the method described above. The device is thus designed to carry out a method according to the invention.

[0049] In particular, the device comprises a transmitting unit and a receiving unit. In particular, the transmitting unit comprises transmitting elements, and the receiving unit comprises receiving elements, in particular sensor pixels. The transmitting elements and receiving elements are preferably combined in a transmitting matrix and a receiving matrix, respectively. A matrix can be understood, in particular, as a three-dimensional, in particular plate-shaped, body on one surface of which the corresponding elements are arranged.

[0050] In particular, the device is a scanning device, preferably a LIDAR sensor. Preferably, the transmitting elements are each a laser, in particular a VCSEL. Furthermore, the transmitting elements can be laser diodes, fiber lasers, or LEDs. Furthermore, the transmitting elements can comprise addressable liquid crystals. Furthermore, the transmitting unit can be an optical phased array. The transmitting elements can be individually controlled.

[0051] The receiving elements are, in particular, linear or nonlinear detectors, especially in the form of an array, preferably a focal plane array, in particular an APD array, most preferably a SPAD array. Furthermore, the array can comprise quantum well structures based on quantum dots.

[0052] The receiving elements can be individually controlled or activated. In particular, each receiving element comprises different areas, in particular a short area for receiving measurement pulses from a short section of the measuring range, a mid area for receiving measurement pulses from a mid section of the measuring range, and a far area for receiving measurement pulses from a far section of the measuring range. The different areas can be individually controlled, activated, and evaluated.

[0053] Furthermore, the device preferably comprises at least one evaluation unit, which is preferably designed to determine the first set and second set of travel times and to create a histogram. Furthermore, the evaluation unit can be designed to read a distance from the histogram.

[0054] In addition, the device may comprise a control unit which is designed to control the transmitting unit, the receiving unit and the evaluation unit.

[0055] Furthermore, the present invention relates to a computer program product comprising a computer-readable storage medium on which a program is stored that enables a computer, after being loaded into the computer's memory, to carry out a method described above, optionally in interaction with a device described above. Furthermore, the invention relates to a computer-readable storage medium on which a program is stored that enables a computer, after being loaded into the computer's memory, to carry out a method described above, optionally in interaction with a device described above. Short description of the drawings

[0056] They show schematically: Figure 1 shows a process diagram of a method according to the invention; Figure 2 shows two directly consecutive measurement intervals; Figure 3 shows the creation of a histogram based on a first measurement after receiving two measurement pulses; Figure 4 shows the creation of a histogram based on a second measurement after receiving two measurement pulses; and Figure 5 shows the histograms of the Figures 3 and 4 and a common histogram. Preferred embodiments of the invention

[0057] In Figure 1 a process diagram of a method 100 according to the invention is shown.

[0058] The method 100 comprises transmitting 101 a first plurality of measurement pulses 13 within a first measurement interval 10 at first transmission times and transmitting 101 a second plurality of measurement pulses 13 within a second measurement interval 11 at second transmission times. The method 100 comprises receiving 103 reflected measurement pulses by means of a receiving element of a receiving unit assigned to the transmitting element at reception times.

[0059] In this case, a short section of the measuring range can be previously assigned a short section of the measuring range, a short section of the receiving element, and a short interval of the corresponding measuring interval. Furthermore, a mid section of the measuring range can be assigned a mid interval of the measuring interval and a mid section of the receiving element, and a far section of the measuring range can be assigned a far section of the measuring range and a far interval of the measuring interval 104. The short section, the mid section, and the far section can be controlled 105 based on the short interval, the mid interval, and the far interval of the first measuring interval 10.

[0060] The method 100 comprises determining 106 a first set of propagation times and determining 107 a second set of propagation times for each received measurement pulse. Furthermore, the method 100 comprises creating 108 a histogram for the receiving element and entering the first set and / or second set of propagation times into the histogram 15. The method may further comprise determining 109 a distance from the histogram 15.

[0061] Figure 2schematically shows two directly consecutive measurement intervals, a first measurement interval 10 and a second measurement interval 11, which are plotted against time 12. Also shown is the detection interval 10a, which begins at the same time as the first measurement interval 10, but is twice as long and thus also extends over the second measurement interval 11. The detection interval 10a can be assigned to the first measurement interval 10 or to both measurement intervals as a common detection interval 10a. In Figure 2 The lengths 30 of the measurement intervals and the length 31 of the detection interval 10a are clearly shown. In each measurement interval, three measurement pulses 13 are emitted, the time intervals of which are randomly selected.

[0062] In Figure 3The creation of a histogram 15 of a first measurement of a first measurement interval 10 after receiving two measurement pulses 13, a first measurement pulse 13a and a second measurement pulse 13b, is shown in a simplified manner. It is therefore shown in a simplified manner because both measurement pulses 13 originate from the same measurement interval and it is assumed that no measurement pulses were transmitted in the previous measurement interval. In other words, this is a temporally first measurement interval 10. Section a) clearly shows the Figure 3 the transmission times of the two measuring pulses 13 can be seen, namely a first transmission time 14a of the first measuring pulse 13a and a second transmission time 14b of the second measuring pulse 13b.

[0063] In section b) of the Figure 3The histogram 15 is shown, which plots entries 16 over time 12 from the beginning of the first measurement interval 10. The hatched positions in the histogram that would be entered without any consideration of the transmission times are shown. In other words, these are the "uncorrected" measured reception times of the two received measurement pulses, namely the first reception time 17a for the first measurement pulse 13a and the second reception time 17b for the second measurement pulse 13b.

[0064] The short arrows on the lower side of the histogram 15 show a shift of these "uncorrected positions" around the first transmission time 14a of the first measurement pulse 13a. The longer arrows shown above show the respective shift 19 around the second transmission time of the second measurement pulse 13b. The shifts provide compensation for the different transmission times. In other words, all possible transmission times are taken into account by subtracting them from the reception times. The hatched entries are not entered, while the other travel times determined by the compensations are entered. In total, four travel times are thus determined, which form the first set of travel times and are entered at the respective positions.It is clearly visible how two entries, one based on the reception of the first measurement pulse 13a and one based on the reception of the second measurement pulse 13b, overlap at one position. This marks the correct runtime 20, while the incorrect runtimes 21 are distributed symmetrically around the correct runtime 20 in the histogram 15.

[0065] In Figure 4 a second measurement of a second measurement interval 11 is shown. In section a), the first transmission time 14c of a first measurement pulse 13c of the second measurement interval 11 and a second transmission time 14d of a second measurement pulse 13d of the second measurement interval 11 can be seen.

[0066] In section b) of the Figure 4shows how the hatched reception times, namely the first reception time 27a for the first measurement pulse 13c and the second reception time 27b for the second measurement pulse 13d, are compensated in the histogram. Compensation is achieved by corresponding shifts, namely initially by a corresponding shift 18 by the first transmission time 14a of the first measurement interval 10, a shift 19 by the second transmission time 14b of the first measurement interval 10, a shift 28 by the first transmission time 14c of the second measurement interval 11, and a shift 29 by the second transmission time 14d of the second measurement interval 11. Compensation is achieved in each case by subtracting the corresponding transmission times from the respective reception time.

[0067] Once again, it is clearly visible how an entry based on both measurement pulses overlaps at the correct position of the travel time, while all other entries are distributed symmetrically around it. By compensating for the emission times of the measurement pulses in the same measurement interval, a first set is formed, while a second set of travel times is formed relative to the emission times of the previous measurement interval.

[0068] In Figure 5 are the histograms 15 of the different measurements of the Figures 3 and 4 shown, where section a) shows the histogram 15 of the first measurement of the first measurement interval 10 of the Figure 3 and section b) the histogram 15 of the second measurement of the second measurement interval 11 of the Figure 4 .

[0069] In section c) a superimposed histogram 15 of the two measurements is shown, which clearly shows how an entry of all received measuring pulses is superimposed at the correct position and thus the correct propagation time 20 and thus distance can be read from the histogram in the simplest way by determining the maximum. List of reference symbols

[0070] 10First measurement interval 10aDetection interval 11Second measurement interval 12Time 13Measurement pulse 13aFirst measurement pulse of the first measurement interval 13bSecond measurement pulse of the first measurement interval 13cFirst measurement pulse of the second measurement interval 13dSecond measurement pulse of the second measurement interval 14aFirst transmission time of the first measurement interval 14bSecond transmission time of the first measurement interval 14cFirst transmission time of the second measurement interval 14dSecond transmission time of the second measurement interval 15Histogram 16Entry 17aFirst reception time of the first measurement interval 17bSecond reception time of the first measurement interval 18Shift by the first transmission time of the first measurement interval 19Shift by the second transmission time of the first measurement interval 20Correct runtime 21Incorrect runtime 27aFirst reception time of the second measurement interval 27bSecond reception time of the second measurement interval 28Shift by the first transmission time of the second measurement interval 29Shift by the second transmission time of the second measurement interval 30Length of a measurement interval 31Length of the detection interval 100Method 101Emission of a first plurality of measurement pulses within a first measurement interval at first transmission times 102Emission of a second plurality of measurement pulses within a second measurement interval at second transmission times 103Reception of reflected measurement pulses by means of a receiving element of a receiving unit assigned to the transmitting element at reception times 104Assignment of a short interval of the measurement interval and a short range of the receiving element to a short section of the measurement range, a mid interval of the measurement interval and a mid range of the receiving element to a mid section of the measurement range, a far interval of the measurement interval and a far range of the receiving element to a far section of the measurement range 105Control of the short range, the mid range and the far range based on the short interval,of the mid-interval and the far-interval of the first measurement interval 106Determining a first set of travel times for each received measurement pulse 107Determining a second set of travel times for each received measurement pulse 108Creating a histogram for the receiving element and entering the first set and / or the second set of travel times 109Determining a distance from the histogram,

Claims

1. Method (100) for optical distance measuring, wherein within a first measuring interval (10) a first plurality of measuring pulses (13) is transmitted (101) by means of a transmitting element of a transmitting unit at first transmission times, wherein within a second measuring interval (11) a second plurality of measuring pulses (13) is transmitted (102) by means of the transmitting element of the transmitting unit at second transmission times, wherein the method (100) comprises receiving (103) reflected measuring pulses by means of a receiving element of a receiving unit assigned to the transmitting element at reception times, characterized in that the method (100) comprises determining (106) a first set of transit times for each received measuring pulse, wherein the first set of transit times is determined using the first transmission times, wherein the method (100) comprises determining (107) a second set of transit times for each received measuring pulse, wherein the second set of transit times is determined using the second transmission times, wherein the first set of transit times is determined using the first transmission times by subtracting each first transmission time from the reception time of the respective received measuring pulse, wherein the second set of transit times is determined using the second transmission times by subtracting each second transmission time from the reception time of the respective received measuring pulse, wherein the first measuring interval (10) and the second measuring interval (11) follow each other directly in time, wherein the method (100) comprises generating (108) at least one histogram (15) for the receiving element and entering the first set and / or the second set of transit times into the histogram.

2. Method according to claim 1, characterized in that the first measuring interval (10) and / or the second measuring interval (11) has a length, where the length is matched to the single or double length of the measuring area.

3. Method (100) according to one of the preceding claims, characterized in that the histogram (15) has the length of the measuring interval.

4. Method (100) according to one of claims 2 or 3, characterized in that only transit times that are greater than zero and smaller than the length of the measuring interval are entered in the histogram.

5. Method (100) according to one of the preceding claims, characterized in that an equal number of measuring pulses (13) is transmitted in the first measuring interval (10) and in the second measuring interval (11).

6. Method (100) according to one of the preceding claims, characterized in that adjacent measuring pulses (13) of the plurality of measuring pulses (13) transmitted within the first measuring interval (10) and / or adjacent measuring pulses (13) of the plurality of measuring pulses transmitted within the second measuring interval (11) have a random spacing from one another.

7. Method (100) according to one of the preceding claims, characterized in that the plurality of measuring pulses (13) transmitted within the first measuring interval (10) and / or the plurality of measuring pulses (13) transmitted within the second measuring interval (11) are coded.

8. Method (100) according to one of the preceding claims, characterized in that at least two of the measuring pulses transmitted within the first measuring interval (10) or the second measuring interval (11) differ in their pulse shape.

9. Method (100) according to one of claims 1 or 3 to 8, characterized in that the measuring area is divided into at least one short section, one mid section and one far section, wherein reflected measuring pulses from the short section, the mid section and the far section are received at different areas of an imaging area of the receiving element, wherein a short interval of the measuring interval and a short area of the receiving element are assigned to the short section, a mid interval of the measuring interval and a mid area of the receiving element are assigned to the mid section, and a far interval of the measuring interval and a far area of the receiving element are assigned to the far section.

10. Method (100) according to claim 9, characterized in that the short area, the mid area and the far area of the receiving element are controlled on the basis of the short interval, the mid interval and the far interval of the first measuring interval.

11. Device for optical distance measuring, wherein the device has a transmitting unit comprising a plurality of transmitting elements for transmitting measuring pulses and a receiving unit comprising a plurality of receiving elements for receiving reflected measuring pulses, characterized in that the device is configured for carrying out a method (100) according to one of claims 1 to 10.

12. Computer program product comprising a computer-readable storage medium on which is stored a program which, after being loaded into the memory of the computer, enables a computer to perform a method (100) according to one of claims 1 to 10 in cooperation with a device according to claim 11.

13. Computer-readable storage medium on which is stored a program which, after being loaded into the memory of the computer, enables a computer to perform a method according to one of claims 1 to 10 in cooperation with a device according to claim 11.