A multi-pixel area combination laser ranging method and device

Abstract

The application provides a multi-pixel area combined laser ranging method and device, the method comprises the following steps: using an FPGA to control a laser diode to emit a laser signal, the laser signal is reflected by a measured object surface and received by a SPAD array chip; the SPAD single-photon avalanche diode array chip comprises a plurality of SPADs with different pixel sizes, after scanning and selecting the plurality of SPADs with different pixel sizes, the laser signal is measured to obtain a plurality of output results; the plurality of output results are stored and the fitting variances of the plurality of output results are calculated; all the fitting variances are compared to obtain a group of data with the minimum fitting variance; the distance corresponding to the group of data with the minimum fitting variance is calculated to obtain distance information obtained by this time ranging. The multi-pixel area combined laser ranging method and device provided by the application use SPADs with different pixel areas, optimize the ranging capability in different scenes, and use corresponding algorithms in the back end, so that the measurement accuracy in each scene is greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photoelectric detection, in particular to a multi-pixel area combined laser ranging method and device. BACKGROUND

[0002] The existing laser ranging technology is difficult to adapt to scenes with large light-dark switching changes and large reflectivity changes in terms of measurement accuracy, and there are certain problems in terms of measurement distance coverage.

[0003] The application patent with publication number CN115792935A and the name of "a ranging method and device of a time-of-flight module" discloses a ranging method of a time-of-flight module, comprising: presetting a first linear relationship between clock-related data of a clock source in the time-of-flight module and an environmental temperature; determining a current temperature value corresponding to the current clock-related data according to the first linear relationship; presetting a second linear relationship between the dark count of the time-of-flight module and the environmental temperature; determining the current dark count corresponding to the current temperature value according to the second linear relationship; eliminating the current dark count from the photon count collected by the time-of-flight module to determine the actual distance between the time-of-flight module and the measured object.

[0004] However, the above-mentioned scheme does not solve how to realize accurate laser ranging in scenes with large light-dark switching changes and large reflectivity changes.

[0005] Therefore, it is necessary to provide a multi-pixel area combined laser ranging method and device to effectively solve the above-mentioned problems. SUMMARY

[0006] The present application provides a multi-pixel area combined laser ranging method and device, which optimizes the ranging capability in different scenes by using SPADs with different pixel areas, and uses corresponding algorithms in the backend, thereby greatly improving the measurement accuracy in each scene.

[0007] The present application provides a multi-pixel area combined laser ranging method, comprising the following steps:

[0008] The FPGA (field programmable gate array) is used to control the laser diode to emit a laser signal, which is reflected by the surface of the measured object and received by the SPAD (single photon avalanche diode) array chip;

[0009] The SPAD array chip includes a plurality of SPADs with different pixel sizes, and the laser signal is measured to obtain a plurality of output results after scanning and selecting the plurality of SPADs with different pixel sizes;

[0010] The multi-output results are stored and the fitting variance of the multi-output results is calculated.

[0011] Compare all the fit variances and obtain the set of data with the smallest fit variance;

[0012] Calculate the distance corresponding to the set of data with the smallest fitting variance to obtain the distance information obtained in this distance measurement.

[0013] Preferably, storing the multi-output results and calculating the fitting variance of the multi-output results includes calculating the bandpass filtering, Gaussian filtering, expectation calculation, and variance calculation of the multi-output results.

[0014] Preferably, the plurality of pixel sizes include 10um, 20um, 30um, 50um, 75um, 100um, 200um, 300um, 500um, 750um, 1mm, and 2mm.

[0015] Preferably, the scanning selection of the multiple SPAD single-photon avalanche diodes of different pixel sizes includes selecting three SPAD single-photon avalanche diodes of different pixel sizes for laser emission each time, and then selecting three more SPAD single-photon avalanche diodes of different pixel sizes for laser emission in sequence until all SPAD single-photon avalanche diodes have been traversed.

[0016] Preferably, the bandpass filter is calculated using the following formula:

[0017]

[0018] Wherein, BaudT is the data after bandpass filtering, T is the multi-channel output result, A is the lower limit of the multi-channel output result, and B is the upper limit of the multi-channel output result.

[0019] Preferably, after bandpass filtering, Gaussian filtering is performed for data smoothing. The Gaussian filtering uses a Gaussian window, which is calculated using the following formula:

[0020]

[0021] Where P represents probability, X represents random variable, N represents that X follows a μ or σ Gaussian distribution, μ represents mean, σ represents standard deviation, and x represents the actual value of X.

[0022] Preferably, the expected value is calculated using the following formula:

[0023]

[0024] Where E(x) is the expected value, x represents the actual value of X, CountM represents the total count within the range of x, n is the number of all data, and FilterT is the filtered data;

[0025] FilterT is calculated using the following formula:

[0026] FilterT = BaudT * W7

[0027] Where W7 is the value of the filter window calculated with a width of 7.

[0028] Preferably, the variance calculation is performed using the following formula:

[0029]

[0030] in, Let denot be the variance, FilterT be the filtered data, W(x) be the expected value, n be the number of data points, and i be a natural number.

[0031] Preferably, the distance information obtained from this ranging measurement is calculated using the following formula:

[0032]

[0033] Where Distance is the distance information obtained in this ranging, K is the system fixed delay, c is the speed of light, FilterT is the filtered data, n is the number of all data, and i is a natural number.

[0034] This invention also provides a multi-pixel area combination laser ranging device, comprising:

[0035] A laser signal emitting module is used to control a laser diode to emit a laser signal using an FPGA (Field Programmable Gate Array). After being reflected by the surface of the object being measured, the laser signal is received by a SPAD (Single Photon Avalanche Diode) array chip, which includes multiple SPAD single photon avalanche diodes of different pixel sizes.

[0036] The multi-output result acquisition module is used to scan and select multiple SPAD single-photon avalanche diodes of different pixel sizes and then measure the laser signal to obtain multi-output results.

[0037] The fitting variance calculation module is used to store the multi-channel output results and calculate the fitting variance of the multi-channel output results;

[0038] The fit variance comparison module is used to compare all fit variances and obtain the set of data with the smallest fit variance.

[0039] The distance information calculation module is used to calculate the distance corresponding to the set of data with the smallest fitting variance, and obtain the distance information obtained in this distance measurement.

[0040] Compared with the prior art, the technical solution of the embodiments of the present invention has the following beneficial effects:

[0041] This invention provides a multi-pixel area combined laser ranging method and apparatus. It uses an FPGA (Field-Programmable Gate Array) to control a laser diode to emit a laser signal. After reflection from the surface of the object being measured, the laser signal is received by a SPAD (Single-Photon Avalanche Diode) array chip. The SPAD array chip includes multiple SPADs of different pixel sizes. After scanning and selecting the multiple SPADs of different pixel sizes, the laser signal is measured to obtain multiple output results. The multiple output results are stored, and the fitting variance of the multiple output results is calculated. All fitting variances are compared, and the set of data with the smallest fitting variance is obtained. The distance corresponding to the set of data with the smallest fitting variance is calculated to obtain the distance information obtained in this ranging operation. By using SPADs with different pixel areas, the ranging capability under different scenarios is optimized.

[0042] Furthermore, storing the multi-output results and calculating the fitting variance of the multi-output results includes calculating the bandpass filtering, Gaussian filtering, expectation calculation, and variance calculation of the multi-output results. By using corresponding algorithms in the backend, the measurement accuracy in various scenarios can be greatly improved. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention, but not all embodiments. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 A flowchart illustrating a multi-pixel area combination laser ranging method according to an embodiment of the present invention;

[0045] Figure 2 A schematic diagram of the operation of a laser diode in a multi-pixel area combination laser ranging method provided in an embodiment of the present invention;

[0046] Figure 3A schematic diagram showing the connection of each module in a multi-pixel area combination laser ranging method according to an embodiment of the present invention;

[0047] Figure 4 This is a schematic diagram of a multi-pixel area combination laser ranging device provided as an embodiment of the present invention. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] The technical solution of the present invention will be described in detail below with reference to specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0050] Based on the problems existing in the prior art, this invention provides a multi-pixel area combined laser ranging method and device. By using SPADs (Single Photon Avalanche Diodes) with different pixel areas, the ranging capability under different scenarios is optimized, and corresponding algorithms are used in the backend, thereby greatly improving the measurement accuracy under various scenarios.

[0051] Figure 1 A flowchart illustrating a multi-pixel area combination laser ranging method according to an embodiment of the present invention; Figure 2 A schematic diagram of the operation of a laser diode in a multi-pixel area combination laser ranging method provided in an embodiment of the present invention; Figure 3 This is a schematic diagram showing the connections of various modules in a multi-pixel area combination laser ranging method according to an embodiment of the present invention. Now refer to... Figures 1-3 This invention provides a multi-pixel area combination laser ranging method, comprising the following steps:

[0052] Step S101: Use an FPGA (Field Programmable Gate Array) to control the laser diode to emit a laser signal, which is then reflected by the surface of the object being measured and received by the SPAD single-photon avalanche diode array chip.

[0053] Step S102: The SPAD single-photon avalanche diode array chip includes multiple SPAD single-photon avalanche diodes of different pixel sizes. After scanning and selecting the multiple SPAD single-photon avalanche diodes of different pixel sizes, the laser signal is measured to obtain multiple output results.

[0054] Step S103: Store the multi-output results and calculate the fitting variance of the multi-output results;

[0055] Step S104: Compare all the fitting variances and obtain the set of data with the smallest fitting variance;

[0056] Step S105: Calculate the distance corresponding to the set of data with the smallest fitting variance to obtain the distance information obtained in this distance measurement.

[0057] Specifically, the SPAD single-photon avalanche diode array chip is biased and powered by a voltage of 21.5V. The SPAD single-photon avalanche diode array chip includes a QC quenching circuit and an analog-to-digital converter circuit for outputting avalanche digital signals. The TDC digital-to-analog conversion is implemented inside the FPGA field-programmable gate array, and the laser diode is located outside the FPGA field-programmable gate array.

[0058] In specific implementation, storing the multi-output results and calculating the fitting variance of the multi-output results includes calculating the bandpass filtering, Gaussian filtering, expectation calculation, and variance calculation of the multi-output results.

[0059] In practical implementation, the SPAD single-photon avalanche diode array chip employs a combination of multiple SPAD single-photon avalanche diodes of different sizes. Specifically, these multiple pixel sizes include 10um, 20um, 30um, 50um, 75um, 100um, 200um, 300um, 500um, 750um, 1mm, and 2mm, totaling 12 pixel sizes, combined to form the SPAD single-photon avalanche diode array chip. SPAD single-photon avalanche diodes with smaller pixel areas have lower response capabilities but less dark count interference, making them advantageous for objects at close range and those with strong reflectivity. SPAD single-photon avalanche diodes with larger pixel areas have better response performance but a larger dark count, providing better response capabilities for distant targets, but the larger dark count may lead to larger errors. Using multiple SPAD single-photon avalanche diodes of different pixel sizes combined to form the SPAD single-photon avalanche diode array chip can optimize ranging capabilities in different scenarios.

[0060] Now see Figure 2In specific implementation, the scanning and selection of the multiple SPAD single-photon avalanche diodes with different pixel sizes includes selecting three SPAD single-photon avalanche diodes of different pixel sizes each time for laser emission, and then sequentially selecting three more SPAD single-photon avalanche diodes of different pixel sizes for laser emission, until all SPAD single-photon avalanche diodes have been traversed. Specifically, the number of laser emission times can be set to, for example, 1000 times. The selection parameters specifically include selecting three SPAD single-photon avalanche diodes each time until all operations are traversed, and then selecting the interface to be used. The parameter range is 0-3. Selecting three single-photon avalanche diodes each time, and selecting four times, will select all 12 single-photon avalanche diodes.

[0061] In specific implementation, the bandpass filter is calculated using the following formula:

[0062]

[0063] Wherein, BaudT is the data after bandpass filtering, T is the multi-channel output result, A is the lower limit of the multi-channel output result, and B is the upper limit of the multi-channel output result.

[0064] In practice, after bandpass filtering, Gaussian filtering is performed for data smoothing. The Gaussian filtering uses a Gaussian window, which is calculated using the following formula:

[0065]

[0066] Where P represents probability, X represents random variable, N represents that X follows a μ or σ Gaussian distribution, μ represents mean, σ represents standard deviation, and x represents the actual value of X.

[0067] In specific implementation, the expected value is calculated using the following formula:

[0068]

[0069] Where E(x) is the expected value, x represents the actual value of X, CountM represents the total count within the range of x, n is the number of all data, and FilterT is the filtered data. The filtered output conforms to a normal distribution.

[0070] FilterT is calculated using the following formula:

[0071] FilterT = BaudT * W7

[0072] Where W7 is the value of the filter window calculated with a width of 7.

[0073] In practice, the variance is calculated using the following formula:

[0074]

[0075] in, Let be the variance, FilterT be the filtered data, E(x) be the expected value, n be the number of data points, and i be a natural number.

[0076] In practice, the distance information obtained from this ranging measurement is calculated using the following formula:

[0077]

[0078] Where Distance represents the distance information obtained in this ranging operation, K is the system fixed delay, c is the speed of light, FilterT is the filtered data, n is the number of all data points, and i is a natural number. The calculation results for each SPAD single-photon avalanche diode are then used. Compare the results, select the largest one, perform distance conversion, and calculate the distance information Distance obtained from this distance measurement.

[0079] Figure 4 A schematic diagram of a multi-band combined laser ranging device provided for one embodiment of the present invention is now shown. Figure 4 This invention also provides a multi-pixel area combination laser ranging device, comprising:

[0080] The laser signal emitting module 41 is used to control the laser diode to emit a laser signal using an FPGA field-programmable gate array. After being reflected by the surface of the object under test, the laser signal is received by the SPAD single-photon avalanche diode array chip. The SPAD single-photon avalanche diode array chip includes multiple SPAD single-photon avalanche diodes of different pixel sizes.

[0081] The multi-output result acquisition module 42 is used to scan and select the multiple SPAD single-photon avalanche diodes of different pixel sizes and then measure the laser signal to obtain multi-output results.

[0082] The fitting variance calculation module 43 is used to store the multi-channel output results and calculate the fitting variance of the multi-channel output results;

[0083] The fitting variance comparison module 44 is used to compare all fitting variances and obtain the set of data with the smallest fitting variance.

[0084] The distance information calculation module 45 is used to calculate the distance corresponding to the set of data with the smallest fitting variance, so as to obtain the distance information obtained in this distance measurement.

[0085] In summary, the multi-pixel area combination laser ranging method and apparatus provided by this invention uses an FPGA (Field Programmable Gate Array) to control a laser diode to emit a laser signal. After reflection from the surface of the object being measured, the laser signal is received by a SPAD (Single Photon Avalanche Diode) array chip. The SPAD array chip includes multiple SPADs of different pixel sizes. After scanning and selecting the multiple SPADs of different pixel sizes, the laser signal is measured to obtain multiple output results. The multiple output results are stored and the fitting variance of the multiple output results is calculated. All fitting variances are compared to obtain the set of data with the smallest fitting variance. The distance corresponding to the set of data with the smallest fitting variance is calculated to obtain the distance information obtained in this ranging operation. By using SPADs of different pixel areas, the ranging capability under different scenarios is optimized.

[0086] Furthermore, storing the multi-output results and calculating the fitting variance of the multi-output results includes calculating the bandpass filtering, Gaussian filtering, expectation calculation, and variance calculation of the multi-output results. By using corresponding algorithms in the backend, the measurement accuracy in various scenarios can be greatly improved.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-pixel area combination laser ranging method, characterized in that, Includes the following steps: The laser diode is controlled by an FPGA (Field Programmable Gate Array) to emit a laser signal, which is then reflected by the surface of the object being measured and received by a SPAD (Single Photon Avalanche Diode Array) chip. The SPAD single-photon avalanche diode array chip includes multiple SPAD single-photon avalanche diodes of different pixel sizes. After scanning and selecting the multiple SPAD single-photon avalanche diodes of different pixel sizes, the laser signal is measured to obtain multiple output results. The multi-output results are stored and the fitting variance of the multi-output results is calculated. Compare all the fit variances and obtain the set of data with the smallest fit variance; Calculate the distance corresponding to the set of data with the smallest fitting variance to obtain the distance information obtained in this distance measurement. The step of storing the multi-output results and calculating the fitting variance of the multi-output results includes calculating the bandpass filtering, Gaussian filtering, expectation calculation, and variance calculation of the multi-output results; The scanning and selection of the multiple SPAD single-photon avalanche diodes of different pixel sizes includes selecting three SPAD single-photon avalanche diodes of different pixel sizes for laser emission each time, and then selecting three more SPAD single-photon avalanche diodes of different pixel sizes for laser emission in sequence until all SPAD single-photon avalanche diodes have been traversed.

2. The multi-pixel area combination laser ranging method according to claim 1, characterized in that, The pixel sizes include 10um, 20um, 30um, 50um, 75um, 100um, 200um, 300um, 500um, 750um, 1mm, and 2mm.

3. The multi-pixel area combination laser ranging method according to claim 1, characterized in that, The bandpass filter is specifically calculated using the following formula: Wherein, BaudT is the data after bandpass filtering, T is the multi-channel output result, A is the lower limit of the multi-channel output result, and B is the upper limit of the multi-channel output result.

4. The multi-pixel area combination laser ranging method according to claim 3, characterized in that, After bandpass filtering, Gaussian filtering is performed for data smoothing. The Gaussian filtering uses a Gaussian window, which is calculated using the following formula: Where P represents probability, X represents random variable, N represents that X follows a μ or σ Gaussian distribution, μ represents mean, σ represents standard deviation, and x represents the actual value of X.

5. The multi-pixel area combination laser ranging method according to claim 4, characterized in that, The expected value is calculated using the following formula: Where E(x) is the expected value, x represents the actual value of X, CountM represents the total count within the range of x, n is the number of all data, and FilterT is the filtered data; FilterT is calculated using the following formula: Where W7 is the value of the filter window calculated with a width of 7.

6. The multi-pixel area combination laser ranging method according to claim 5, characterized in that, The variance is calculated using the following formula: in, For variance, The filtered data, For the expected value, The number of all data points. It is a natural number.

7. The multi-pixel area combination laser ranging method according to claim 6, characterized in that, The distance information obtained from this distance measurement is specifically calculated using the following formula: in, This is the distance information obtained from this distance measurement. For a fixed system delay, At the speed of light, The filtered data, The number of all data points. It is a natural number.

8. A multi-pixel area combination laser ranging device, characterized in that, include: A laser signal emitting module is used to control a laser diode to emit a laser signal using an FPGA (Field Programmable Gate Array). After being reflected by the surface of the object being measured, the laser signal is received by a SPAD (Single Photon Avalanche Diode) array chip, which includes multiple SPAD single photon avalanche diodes of different pixel sizes. The multi-output result acquisition module is used to scan and select multiple SPAD single-photon avalanche diodes of different pixel sizes and then measure the laser signal to obtain multi-output results. The fitting variance calculation module is used to store the multi-channel output results and calculate the fitting variance of the multi-channel output results; The fit variance comparison module is used to compare all fit variances and obtain the set of data with the smallest fit variance. The distance information calculation module is used to calculate the distance corresponding to the set of data with the smallest fitting variance, and obtain the distance information obtained in this distance measurement. The step of storing the multi-output results and calculating the fitting variance of the multi-output results includes calculating the bandpass filtering, Gaussian filtering, expectation calculation, and variance calculation of the multi-output results; The scanning and selection of the multiple SPAD single-photon avalanche diodes of different pixel sizes includes selecting three SPAD single-photon avalanche diodes of different pixel sizes for laser emission each time, and then selecting three more SPAD single-photon avalanche diodes of different pixel sizes for laser emission in sequence until all SPAD single-photon avalanche diodes have been traversed.

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