A histogram processing method and radar system based on a planar array DTOF radar

Abstract

This application discloses a histogram processing method and radar system based on a DTOF radar array, relating to the field of radar ranging technology, to meet user requirements regarding the actual circuit area occupied by information storage space and the histogram processing time. The method includes: within any time flight window during the coarse measurement process, reading the number of digital signal data corresponding to all signal conversion modules stored in each subspace of the storage space, in ascending order of the coarse data range matched by the corresponding histogram interval; one histogram interval corresponds to one coarse data range, and the information storage space includes multiple subspaces that correspond one-to-one with multiple histogram intervals; storing the updated number of digital signal data transmitted by the signal conversion module that falls into each histogram interval in the storage location matched by the signal conversion module in the subspace corresponding to the histogram interval.

Description

Technical Field

[0001] This application relates to the field of radar ranging technology, and in particular to a histogram processing method and radar system based on a surface array DTOF radar. Background Technology

[0002] In radar systems using DTOF radar for ranging, the TDC (Transient DC-DC) circuit array serves as a crucial bridge connecting the analog front-end and digital back-end of the DTOF radar. It features support for high-resolution area arrays, multi-event operation, gating, and NFC support, thereby enhancing the radar system's performance. During the ranging and imaging process using DTOF radar, a histogram needs to be generated. Then, based on the histogram, the distance measured by each pixel unit corresponding to each TDC is determined, ultimately yielding the ranging image of the radar system.

[0003] Currently, when generating histograms, each TDC corresponds to an independent histogram generation logic. The digital processing module of the radar system consumes a lot of logic resources, and each TDC corresponds to an independent histogram data storage location, which requires more storage area when constructing the histogram generation circuit. Furthermore, under high repetition rate measurement, the time available for histogram generation processing is short. The area of ​​the histogram generation circuit and the processing time of the histogram are difficult to achieve the ideal state expected by users. Summary of the Invention

[0004] This application provides a histogram processing method and radar system based on a surface array DTOF radar, which can meet the user's requirements regarding the actual circuit area occupied by information storage space and the histogram processing time.

[0005] To achieve the above technical objectives, this application adopts the following technical solution:

[0006] In a first aspect, embodiments of this application provide a histogram processing method based on a planar array DTOF radar, applied to a radar system, the radar system including multiple signal conversion modules and a digital processing module; the method includes:

[0007] The digital processing module divides a preset number of histogram intervals and a preset number of coarse data ranges based on the ranging range of the radar system, and establishes a correspondence between the preset number of histogram intervals and the preset number of coarse data ranges, with one histogram interval corresponding to one coarse data range.

[0008] The digital processing module divides the information storage space into multiple subspaces that correspond one-to-one with multiple histogram intervals;

[0009] The signal conversion module receives the pulse signal triggered by the ranging echo, converts the time difference between the moment the pulse signal is received and the start time of the current time flight window into digital signal data, and sends the digital signal data to the digital processing module.

[0010] During any time flight window in the coarse measurement process, the digital processing module reads the number of digital signal data corresponding to all signal conversion modules stored in each subspace of the storage space in ascending order of the coarse data range matched by the corresponding histogram interval.

[0011] After receiving the digital signal data transmitted by each signal conversion module, the digital processing module updates the number of digital signal data transmitted by the signal conversion module that falls into the histogram interval based on the histogram interval into which the digital signal data falls, and the number of digital signal data corresponding to the signal conversion module within the histogram interval. The updated number of digital signal data transmitted by the signal conversion module that falls into each histogram interval is then stored in the storage location matching the signal conversion module in the subspace corresponding to the histogram interval. The subspace includes the storage location corresponding to each signal conversion module.

[0012] The technical solution provided in this application offers at least the following advantages: All digital signal data transmitted by the signal conversion modules in the radar system is stored in the information storage space, eliminating the need for separate independent storage spaces for each signal conversion module and saving actual circuit area occupied by the information storage space. The subspaces within the information storage space correspond one-to-one with histogram intervals. When the digital processing module reads data from the storage space, it sequentially reads the data in each subspace according to the order of the coarse data range matched by the corresponding histogram interval from smallest to largest. That is, for a radar system using a DTOF radar array for ranging, the number of histogram intervals divided corresponds to the number of times the digital processing module reads the subspace within a single time flight window. Compared to reading the independent storage spaces corresponding to each signal conversion module separately, the number of histogram intervals is far less than the number of signal conversion modules. Therefore, the number of times the digital processing module reads data is greatly reduced, correspondingly saving processing time for the histogram data. Since radar ranging always receives the echo reflected from the nearest object first, meaning the digital processing module always receives the digital signal data corresponding to the shortest time difference transmitted by each signal conversion module first, the data in each subspace is read sequentially according to the coarse data range matched by the corresponding histogram interval, taking into account the time order of data storage. Therefore, a single read operation within the information storage space within a single time flight window is sufficient to read all the data stored in the information storage space, eliminating the need for secondary data readings and reducing the time spent on repeated data retrieval. Thus, under high repetition rate measurements, the histogram processing method of this application does not require increasing the area of ​​the histogram generation circuit and saves histogram processing time, meeting the user's requirements regarding the actual circuit area occupied by the information storage space and the histogram processing time.

[0013] In one possible implementation, the method further includes: within any time flight window of the fine measurement process, the digital processing module sequentially reads the number of digital signal data in each histogram interval stored in the storage location corresponding to each signal conversion module in the storage space, according to the pre-set arrangement order of the signal processing modules.

[0014] In one possible implementation, the method further includes: for each signal conversion module, after the coarse measurement process of the first preset number of time-flying windows is completed, the digital processing module obtains a coarse histogram corresponding to the signal conversion module; the digital processing module performs peak-finding processing on the coarse histogram to obtain the coarse histogram interval corresponding to the peak value of the coarse histogram; the digital processing module divides the coarse data range corresponding to the coarse histogram interval into a preset number of fine data ranges; the digital processing module changes the coarse data range corresponding to each histogram interval into a corresponding fine data range; the digital processing module performs a fine measurement process of the second preset number of time-flying windows to obtain a fine histogram corresponding to the signal conversion module; the digital processing module performs peak-finding processing on the fine histogram to obtain the fine histogram interval corresponding to the peak value of the fine histogram; the digital processing module combines the coarse data range corresponding to the coarse histogram interval and the fine data range corresponding to the fine histogram interval to obtain the measurement distance corresponding to the signal conversion module; the digital processing module combines the measurement distances corresponding to each signal conversion module to output the depth image measured by the radar system.

[0015] In one possible implementation, after the coarse measurement process of the first preset number of time-flying windows is completed, the digital processing module obtains a coarse histogram corresponding to the signal conversion module, including: the digital processing module determining that the range of digital signal data transmitted by the signal conversion module during the coarse measurement process is the full range, and sending indication information for indicating the full range to each signal conversion module; the signal conversion module receiving the indication information, and transmitting all digital signal data converted by the signal conversion module to the digital processing module within each time-flying window of the coarse measurement process; after the coarse measurement process of the first preset number of time-flying windows is completed, the digital processing module generates a coarse histogram corresponding to the signal conversion module based on the number of digital signal data stored in the storage locations matching the signal conversion modules in each subspace of the storage space.

[0016] In one possible implementation, after the coarse measurement process of the first preset number of time-flying windows is completed, the method further includes: the digital processing module deleting the digital signal data stored in the storage space during the coarse measurement process; the digital processing module performing a fine measurement process of the second preset number of time-flying windows to obtain a fine histogram corresponding to the signal conversion module, including: the digital processing module sending the coarse data range corresponding to the coarse histogram interval to the corresponding signal conversion module; the signal conversion module receiving the coarse data range corresponding to the coarse histogram interval sent by the digital processing module, filtering out the digital signal data that does not fall within the coarse data range corresponding to the coarse histogram interval, and transmitting the digital signal data that falls within the coarse data range corresponding to the coarse histogram interval to the digital processing module; the digital processing module receiving the digital signal data that falls within the coarse data range corresponding to the coarse histogram interval transmitted by the signal conversion module; after the fine measurement process of the second preset number of time-flying windows is completed, the digital processing module generating a fine histogram corresponding to the signal conversion module based on the digital signal data stored in the storage location corresponding to the signal conversion module in each histogram interval in the storage space.

[0017] In one possible implementation, the digital processing module receives digital signal data transmitted by the signal conversion module that falls within the coarse data range corresponding to the coarse histogram interval. This includes: the digital processing module dividing the time flight window into a preset number of time slices, where each time slice corresponds to a histogram interval, and each time slice is less than or equal to a pixel dead time; the digital processing module determining a target time slice corresponding to the coarse histogram interval; and the digital processing module receiving digital signal data transmitted by the signal conversion module within the coarse data range corresponding to the coarse histogram interval in the target time slice.

[0018] In one possible implementation, the method further includes: during the coarse measurement process, if the digital processing module receives digital signal data transmitted by the signal conversion module within a first time slice, it records a first value corresponding to the first time slice; if it does not receive digital signal data transmitted by the signal conversion module within the first time slice, it records a second value corresponding to the first time slice; the first time slice is any time slice within a time flight window; the digital processing module updates the number of digital signal data transmitted by the signal conversion module that falls into the histogram interval based on the histogram interval into which the digital signal data falls, and the number of digital signal data corresponding to the signal conversion module within the histogram interval read from the signal conversion module, including: the digital processing module determining the histogram interval corresponding to the first time slice; the digital processing module summing the first value or the second value corresponding to the first time slice with the number of digital signal data read from the signal conversion module within the histogram interval corresponding to the first time slice to obtain the updated number of digital signal data transmitted by the signal conversion module that falls into the histogram interval.

[0019] In one possible implementation, during the fine measurement process, the digital processing module updates the number of digital signal data transmitted by the signal conversion module that falls into the histogram interval based on the histogram interval into which the digital signal data falls and the number of digital signal data corresponding to the signal conversion module within the histogram interval. This includes: for each histogram interval, if the digital signal data transmitted by the signal conversion module falls into the histogram interval, the digital processing module increments the number of digital signal data corresponding to the signal conversion module within the histogram interval by 1 to obtain the updated number of digital signal data transmitted by the signal conversion module that falls into the histogram interval.

[0020] Secondly, this application provides a radar system; the radar system includes a laser emitting module, an echo receiving module, multiple signal conversion modules, and a digital processing module; the laser emitting module is used to emit ranging lasers at a preset frequency; the echo receiving module includes multiple pixel units, one pixel unit corresponding to one signal conversion module; the pixel unit is used to receive ranging echoes within a time flight window after the laser emitting module emits a ranging laser once, and sends pulse signals to the corresponding signal conversion module when receiving the ranging echo; the signal conversion module is used to record the time when the pulse signal sent by the corresponding pixel unit is received, convert the time difference between the time when the pulse signal sent by the corresponding pixel unit is received and the start time of the current time flight window into digital signal data, and send the digital signal data to the digital processing module; the digital processing module is used to divide a preset number of histogram intervals, and divide a preset number of coarse data ranges based on the ranging range of the radar system, and establish a relationship between the preset number of histogram intervals and the preset number of coarse data ranges. The correspondence is as follows: one histogram interval corresponds to one coarse data range. The digital processing module is used to divide the information storage space into multiple subspaces that correspond one-to-one with multiple histogram intervals. Within any time flight window in the coarse measurement process, the digital processing module is used to read the quantity of digital signal data corresponding to all signal conversion modules stored in all subspaces of the storage space in ascending order of the coarse data range matched by the corresponding histogram interval. After receiving the digital signal data transmitted by each signal conversion module, the digital processing module updates the quantity of digital signal data transmitted by the signal conversion module that falls into the histogram interval based on the histogram interval into which the digital signal data falls, and the quantity of digital signal data corresponding to the signal conversion module read from the histogram interval. The updated quantity of digital signal data transmitted by the signal conversion module that falls into each histogram interval is then stored in the storage location matched by the signal conversion module in the subspace corresponding to the histogram interval. The subspace includes the storage location corresponding to each signal conversion module.

[0021] Thirdly, this application provides a radar system, including: a processor; a memory; wherein the memory is used to store computer program code, the computer program code including computer instructions, and when the processor executes the computer instructions, the radar system executes any of the histogram processing methods based on area array DTOF radar provided in the first aspect above.

[0022] Fourthly, this application provides a computer-readable storage medium storing computer-executable instructions, which, when executed on a computer, cause the computer to perform any of the histogram processing methods based on area array DTOF radar provided in the first aspect above.

[0023] Fifthly, this application provides a computer program product including computer instructions that, when executed on a computer, cause the computer to perform the histogram processing method for a surface array DTOF radar as described in the first aspect and any possible design thereof.

[0024] For a detailed description of the second to fifth aspects and their various implementations in this application, please refer to the detailed description in the first aspect and its various implementations; and for a detailed analysis of the beneficial effects of the second to fifth aspects and their various implementations in the first aspect and its various implementations, please refer to the beneficial effect analysis in the first aspect and its various implementations, which will not be repeated here.

[0025] These or other aspects of this application will become more readily apparent in the following description. Attached Figure Description

[0026] Figure 1 A schematic diagram of the radar system architecture to which the histogram processing method based on a surface array DTOF radar provided in this application embodiment is applicable;

[0027] Figure 2 This is a schematic diagram of the specific structure of a radar system provided in an embodiment of this application;

[0028] Figure 3 This application provides a schematic diagram of the structure of a radar system in a related art.

[0029] Figure 4 A comparative schematic diagram showing the data throughput of a single-point pixel unit and an area array pixel unit, provided for embodiments of this application;

[0030] Figure 5 A comparative diagram of single-event TDC and multi-event TDC triggering events within a single time flight window, provided for embodiments of this application;

[0031] Figure 6A schematic diagram comparing the amount of data transmitted with and without NFC features, provided as an embodiment of this application;

[0032] Figure 7 This application provides an illustration of an application scenario for a histogram processing method based on a planar array DTOF radar, as provided in this embodiment. Figure 1 ;

[0033] Figure 8 A flowchart illustrating a histogram processing method based on an area array DTOF radar, provided for embodiments of this application;

[0034] Figure 9 This application provides an illustration of an application scenario for a histogram processing method based on a planar array DTOF radar, as provided in this embodiment. Figure 2 ;

[0035] Figure 10 This application provides an illustration of an application scenario for a histogram processing method based on a planar array DTOF radar, as provided in this embodiment. Figure 3 ;

[0036] Figure 11 This application provides an illustration of an application scenario for a histogram processing method based on a planar array DTOF radar, as provided in this embodiment. Figure 4 ;

[0037] Figure 12 This application provides an illustration of an application scenario for a histogram processing method based on a planar array DTOF radar, as provided in this embodiment. Figure 5 ;

[0038] Figure 13 This is a logical schematic diagram of a histogram processing method based on a surface array DTOF radar provided in an embodiment of this application. Detailed Implementation

[0039] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0040] It should be noted that, in the embodiments of this application, the terms "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design scheme described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design schemes. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a specific manner. The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0041] To facilitate understanding, we will first provide a brief introduction and explanation of some terms or basic concepts of technology involved in the embodiments of this application.

[0042] Direct Time of Flight (DTOF) radar: This type of lidar measures distance using direct time of flight. Its ranging principle utilizes the speed of light in the air. By emitting a beam of light and measuring the time difference between its emission, reflection, and return to the detector, the distance between the object and the sensor is calculated, thus achieving distance detection. DTOF radar has advantages such as a wide ranging range and high accuracy, and is widely used in smart homes, transportation, robotics, and other applications.

[0043] Single-photon avalanche diode (SPAD): Due to its high sensitivity to photons, a single photon can trigger its avalanche breakdown, and the array quenching recovery speed after breakdown is relatively fast. It is often used as the pixel array of array DTOF to realize the detection and reception of laser echoes.

[0044] Time-to-digital converter (TDC): A sensor that converts a time signal into a specifically encoded digital electrical signal.

[0045] Multi-Event TDC: Within a single measurement time flight window, TDC can perform multiple measurements and output the results of multiple measurements.

[0046] Support for noise filter circuits (NFC): A filter circuit used to process several SPAD sub-pixels stitched together to form a SPAD macro-pixel. The triggering conditions of the macro-pixel can be changed by dynamically setting the threshold, switching between circuit resistance to ambient light interference and photon utilization.

[0047] The above is an introduction to some of the concepts involved in the embodiments of this application, which will not be repeated below.

[0048] In a DTOF radar system, the TDC (Transient DC-DC) circuit array serves as a crucial bridge connecting the analog front-end and digital back-end of the radar system. It supports features such as high-resolution arrays, multi-event operation, gating, and NFC (Near Field Communication), thereby enhancing the radar system's performance. During radar ranging and imaging, a histogram needs to be generated. Then, based on the histogram, the distance measured by the corresponding pixel unit of each TDC is determined, ultimately yielding the ranging image of the radar system.

[0049] For histogram processing in area array DTOF radar, a common approach is to combine coarse and fine measurement methods to save storage space. However, this method requires each TDC (Transient Data Center) to generate its own histogram, resulting in a larger storage area for the histogram generation circuit. Furthermore, the amount of data transmitted per measurement is substantial; for every N TDCs in the radar system, there must be N parallel histogram generation logic units, consuming significant logic resources in the radar system's data processing module. Additionally, due to the high parallelism requirement for TDCs, the time allotted for histogram generation is limited during high-repetition-rate measurements.

[0050] The general idea behind the traditional coarse-fine histogram generation method is as follows: A few high bits of the TDC (Transformer Data Center) are used as coarse count values, and a few low bits are used as fine count values. Each coarse and fine count is accompanied by a few bits of NFC-weighted data. During the coarse measurement, only the high bits of TDC data are received to generate a coarse histogram. Then, peak finding is performed on the coarse histogram, and the found coarse peak value is used as a gating window for the TDC. During the fine search, the TDC obtains the range of the gating window and only sends the low bits of data triggered within the coarse peak value range. These low bits are used for histogram statistics to obtain the fine histogram. Then, peak finding is performed on the fine histogram, and the obtained coarse and fine peak values ​​are merged to obtain the final complete bit peak value.

[0051] Driven by a multi-event time-of-flight controller (TDC), a TDC may output data at each pixel dead time interval. A single TDC can produce a maximum of (time-of-flight window) / (pixel dead time) different measurement data in a single measurement. The number of events increases exponentially with the number of TDCs. Each TDC requires an independent histogram, so its logic must be independent. Generally, the following approaches can be used to implement this scheme:

[0052] One approach is to increase the size of the cache while simultaneously increasing the frequency of the digital circuit (several times the pixel dead time period). The cache size needs to ensure that the processing time is consistent with the new data input time, thereby ensuring consistent throughput. This approach generally requires moderate array cache resources, has high requirements for the main frequency of the digital circuit, and thus high requirements for the digital process node.

[0053] Another approach is to sacrifice repetition time to reduce the number of measurements and frame rate, while caching the complete data of a single measurement and waiting for all TDC corresponding trigger events to be completed before performing the next measurement. This approach requires caching the complete data of all TDCs in a single measurement, but it can serially execute multiplexed histogram statistical logic resources to a large extent. However, it will severely affect the measurement frame rate and laser repetition frequency.

[0054] Another approach is to merge and store histograms, storing histogram data from multiple different TDCs together, and then using an algorithm to reconstruct and separate the histograms of individual pixels. However, this approach cannot obtain the true original histograms, and too much histogram data is lost. If there are multiple peaks or multiple targets, it is impossible to reconstruct them at all.

[0055] Therefore, a histogram generation method is still needed that can achieve the ideal state expected by the user in terms of the area of ​​the histogram generation circuit and the processing time of the histogram.

[0056] To address this issue, this application provides a histogram processing method based on an area-array DTOF radar. All digital signal data transmitted by the signal conversion modules in the radar system are stored in an information storage space, eliminating the need for separate independent storage spaces for each signal conversion module and saving actual circuit area occupied by the information storage space. The subspaces within the information storage space correspond one-to-one with histogram intervals. When the digital processing module reads data from the storage space, it sequentially reads data from each subspace in ascending order of the coarse data range matched by the corresponding histogram interval. That is, for a radar system using an area-array DTOF radar for ranging, the number of histogram intervals divided corresponds to the number of times the digital processing module reads the subspace within a single time flight window. Compared to reading the independent storage spaces corresponding to each signal conversion module separately, the number of histogram intervals is much smaller than the number of signal conversion modules, thus significantly reducing the number of times the digital processing module reads data and correspondingly saving processing time for the histogram data. Since radar ranging always receives the echo reflected from the nearest object first, meaning the digital processing module always receives the digital signal data corresponding to the shortest time difference transmitted by each signal conversion module first, the data in each subspace is read sequentially according to the coarse data range matched by the corresponding histogram interval, taking into account the time order of data storage. Therefore, a single read operation within the information storage space within a single time flight window is sufficient to read all the data stored in the information storage space, eliminating the need for secondary data readings and reducing the time spent on repeated data retrieval. Thus, under high repetition rate measurements, the histogram processing method of this application does not require increasing the area of ​​the histogram generation circuit and saves histogram processing time, meeting the user's requirements regarding the actual circuit area occupied by the information storage space and the histogram processing time.

[0057] Please refer to Figure 1 This illustrates the radar system to which the histogram processing method based on a surface-array DTOF radar provided in this application is applicable. Figure 1 As shown, the radar system 1 includes: a laser emitting module 10, an echo receiving module 20, multiple signal conversion modules 30, and a digital processing module 40.

[0058] The digital processing module 40 establishes communication connections with the laser emitting module 10, the echo receiving module 20, and the signal conversion module 30, respectively, and the echo receiving module 20 establishes a communication connection with the signal conversion module 30. It should be understood that the connection method can be wireless, such as Bluetooth or Wi-Fi; or it can be wired, such as fiber optic, etc., without limitation. For example, the digital processing module 40 is connected to the laser emitting module 10, the echo receiving module 20, and the signal conversion module 30 via lines, thereby realizing the communication connections between the digital processing module 40 and these modules.

[0059] In some embodiments, the laser emitting module 10 is used to emit a ranging laser at a preset frequency.

[0060] In some embodiments, the echo receiving module 20 is used to receive ranging echoes. Specifically, the echo receiving module 20 may be a SPAD pixel array.

[0061] Specifically, the echo receiving module 20 includes multiple pixel units, with one pixel unit corresponding to one signal conversion module 30. The pixel unit receives the ranging echo within a time-flying window after the laser emitting module 10 emits a ranging laser, and sends a pulse signal to the corresponding signal conversion module 30 upon receiving the ranging echo. The time-flying window can be understood as a time period, starting at the moment the laser emitting module 10 emits the ranging laser, and its duration is a preset duration. By using multiple pixel units, the actual photosensitive area can be increased, improving the utilization efficiency of the laser echo.

[0062] In some embodiments, the signal conversion module 30 is used to convert the time difference between the moment when the corresponding pixel unit sends a pulse signal and the start time of the current time flight window into digital signal data, and send the digital signal data to the digital processing module 40. Specifically, the signal conversion module 30 is a TDC array.

[0063] In some embodiments, the digital processing module 40 is used to divide a preset number of histogram intervals and, based on the ranging range of the radar system 1, divide a preset number of coarse data ranges, and establish a correspondence between the preset number of histogram intervals and the preset number of coarse data ranges, with one histogram interval corresponding to one coarse data range. The digital processing module 40 is also used to divide the information storage space into multiple subspaces that correspond one-to-one with multiple histogram intervals; within any time flight window in the coarse measurement process, the digital processing module 40 is also used to read the number of digital signal data corresponding to all signal conversion modules 30 stored in all subspaces of the storage space in ascending order of the coarse data range matched by the corresponding histogram interval; after receiving the digital signal data transmitted by each signal conversion module 30, the digital processing module 40 is also used to update the number of digital signal data transmitted by the signal conversion module 30 that falls into the histogram interval based on the histogram interval into which the digital signal data falls, and the number of digital signal data corresponding to the signal conversion module 30 read in the histogram interval, and store the updated number of digital signal data transmitted by the signal conversion module 30 that falls into each histogram interval in the storage location matched by the signal conversion module 30 in the subspace corresponding to the histogram interval, the subspace including the storage location corresponding to each signal conversion module 30.

[0064] Specifically, the information storage space can be a single block of random access memory (RAM). The byte enable function built into the RAM itself can minimize the read and write operations when using large blocks of RAM with high density and small area.

[0065] In practical applications, the digital processing module 40 can be a processor, or it can be a circuit structure composed of MOS transistors.

[0066] In some embodiments, the radar system 1 in this application can be a surface array radar system. The surface array radar system can support hundreds to thousands of TDC parallel processing, and adopts a combination of coarse and fine measurement. When the digital clock is asynchronous with the TDC, it supports multiple events (time signals converted into digital signals) triggered within a time flight window, and each event supports NFC weighting (that is, the above pixel unit is a macro pixel, and each macro pixel is composed of multiple sub-pixels and NFC circuits).

[0067] For example, the specific structure of radar system 1 can be as follows: Figure 2As shown, the laser emitting module emits a ranging laser, which is reflected by the target. The reflected laser echo is received by the SPAD macropixel array. When a pixel unit (macropixel) in the SPAD macropixel array receives the laser echo, it sends a pulse signal to the TDC corresponding to that pixel unit. The TDC then converts the time signal into a digital signal and transmits it to the digital processing module. The digital processing module stores the digital signal transmitted by each TDC in the subspace corresponding to the histogram interval into which the data falls, at the storage location corresponding to that TDC. After the coarse measurement process, the digital processing module also performs "gated feedback calibration," that is, determines the coarse measurement range corresponding to the coarse histogram interval, and finally feeds back the coarse measurement range to the corresponding TDC for filtering the digital signal data in the subsequent fine measurement process. For example, Figure 2 As shown in the dashed box, a macro pixel consists of 4×4 sub-pixels and an NFC circuit. Figure 2 (This is merely an example; this application does not impose specific limitations on the number of sub-pixels constituting a macropixel.) One macropixel corresponds to one TDC. After a macropixel is effectively triggered, it sends a pulse signal to the corresponding TDC. When all sub-pixels in a macropixel exceeding a preset threshold are triggered, the macropixel is effectively triggered. The preset threshold can be set via NFC. For example, a host computer (such as a CPU) determines the ambient light intensity of the current environment through algorithm and histogram analysis. The host computer can then control NFC to dynamically set and adjust the preset threshold. If the current environment is under strong light, the NFC can be controlled to increase the preset threshold, reducing the possibility of false triggering of macropixels due to excessive ambient light intensity, thus resisting ambient light interference. If the current environment is under weak light, the NFC can be controlled to decrease the preset threshold, avoiding missed detections caused by actual triggering of sub-pixels in the macropixel when the preset threshold is low, thus improving photon utilization efficiency. Through NFC settings, a balance can be achieved between resisting ambient light interference and photon utilization, improving the efficiency and confidence of a single measurement.

[0068] like Figure 3 As shown, in related technologies, when storing digital signal data transmitted by a TDC, each TDC has its own independent storage space for histogram data. The coarse measurement data output by the TDC during the coarse measurement process and the fine measurement data output during the fine measurement process are both stored in the corresponding storage space to ensure the original output of the data. This results in a large storage space occupied by the digital signal data.

[0069] In this application, the coarse measurement process stores the quantity corresponding to the digital signal data, not the data itself, thus reducing the storage resources occupied. After the coarse measurement process is completed, the quantity recorded in the coarse measurement process will be deleted. The digital signal data in the fine measurement process will also be stored in the subspace corresponding to the histogram interval in the coarse measurement process. No separate histogram interval is set for the fine measurement process. That is, the coarse measurement process and the fine measurement process use the same information storage space, thus reducing the area of ​​information storage space.

[0070] Based on the above description, radar system 1 has the following characteristics:

[0071] ① High-resolution characteristics of area array. Figure 4 This shows the data throughput corresponding to a single-point pixel unit and an area pixel unit. Figure 4 The left side shows the data throughput corresponding to a single pixel unit. Figure 4 The right side shows the data throughput corresponding to the area array pixel unit. The area array pixel unit increases the number of TDCs processed in parallel at the same time, and the data throughput received by the digital processing module increases linearly. For example, the original single-point pixel unit corresponds to only one TDC, and at most only one TDC will be processed in parallel. However, for the area array pixel unit, there may be N TDCs at the same time, exposing the corresponding pixel array in a roll / row / column / block manner. Then its parallelism increases linearly by N times, and the parallelism and complexity increase.

[0072] ② Multi-event feature. To improve photon utilization efficiency, most TDCs support multi-event triggering. Figure 5 This is a diagram illustrating how single-event TDC and multi-event TDC trigger events within a single time flight window. Figure 5 The left side shows the number of events triggered by a single event TDC within a single time flight window. Figure 5 The right side shows the number of times a multi-event TDC triggers an event within a single time flight window. A multi-event TDC can generate multiple sets of measurement data within a fixed time flight window. Compared to a traditional single-event TDC that generates only one set of data per flight window, this characteristic has the greatest impact on the digital processing module. The surge in sudden data volume within a fixed time flight window places further demands on data throughput.

[0073] ③ Supports Notification Filtering (NFC) feature. NFC is a method to improve photon efficiency by stitching together multiple sub-pixels to form a macropixel. It determines the actual triggering of the macropixel by setting a preset threshold for the number of trigger sub-pixels, and simultaneously encodes the NFC value of each trigger. In subsequent histogram statistics, a notification filter (NFC) weighting value is added to the trigger value of the TDC, thereby improving the confidence of the histogram. However, this relatively increases the amount of data transmitted in each TDC. Figure 6The comparison of data transmission volume with and without NFC features is shown. Taking NFC, which consists of 16 sub-pixels forming one macro-pixel, as an example, the transmission value triggered by TDC needs to be increased by at least 4 bits of NFC weighting value each time, thereby further increasing the transmission bandwidth between TDC and digital processing module and increasing the pressure on data throughput requirements.

[0074] ④ The gated window feature refers to the TDC's filtering of time signals, allowing only triggering events within a specific time range to be quantized into digital signal data. This feature requires feedback calibration from the digital processing module. After calibrating the filtering range, specific time signals can be filtered. This feature can be applied in coarse and fine measurement processes to reduce storage resources, such as... Figure 7 As shown, after the digital processing module determines the coarse data range (gating window filtering range) corresponding to the coarse histogram, it feeds it back to the TDC. The TDC then quantizes the time signals within the gating window filtering range into digital signal data and transmits them to the digital processing module.

[0075] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0076] The histogram processing method based on area array DTOF radar provided in this application embodiment is applied to the radar system 1 described above.

[0077] like Figure 8 As shown in the figure, this application provides a histogram processing method based on a planar array DTOF radar, which includes the following steps:

[0078] S101, the digital processing module divides a preset number of histogram intervals and a preset number of coarse data ranges based on the ranging range of the radar system, and establishes the correspondence between the preset number of histogram intervals and the preset number of coarse data ranges.

[0079] One histogram interval corresponds to one coarse data range.

[0080] For example, the ranging range of the radar system is 0-100 meters, and the preset number can be set to 10. The coarse data range can be either the distance range or the time range required to measure that distance. For instance, the digital processing module divides the range into 10 distance ranges: 0-10 meters, 10-20 meters, 20-30 meters, 30-40 meters, 40-50 meters, 50-60 meters, 60-70 meters, 70-80 meters, 80-90 meters, and 90-100 meters. Alternatively, the time required for the ranging laser to travel from emission to reflection from 10 meters to reception by the echo receiver module is x1; the time required for the ranging laser to travel from emission to reflection from 20 meters to reception by the echo receiver module is x2; the time required for the ranging laser to travel from emission to reflection from 30 meters to reception by the echo receiver module is x3; the time required for the ranging laser to travel from emission to reflection from 40 meters to reception by the echo receiver module is x4; the time required for the ranging laser to travel from emission to reflection from 50 meters to reception by the echo receiver module is x5; and the time required for the ranging laser to travel from emission to reflection from 60 meters to reception by the echo receiver module is x6. The time required for the ranging laser to reflect off the target laser at 70 meters and be received by the echo receiver module is x7. The time required for the ranging laser to reflect off the target laser at 80 meters and be received by the echo receiver module is x8. The time required for the ranging laser to reflect off the target laser at 90 meters and be received by the echo receiver module is x9. The time required for the ranging laser to reflect off the target laser at 100 meters and be received by the echo receiver module is x10. These 10 coarse data ranges constitute 10 time ranges: 0-x1, x1-x2, x2-x3, x3-x4, x4-x5, x5-x6, x6-x7, x7-x8, x8-x9, x9-x10. The digital processing module divides these into 10 histogram intervals: interval 0, interval 1, interval 2, interval 3, interval 4, interval 5, interval 6, interval 7, interval 8, and interval 9. Then, the digital processing module establishes a one-to-one correspondence between 10 distance ranges and 10 histogram intervals, or the digital processing module establishes a one-to-one correspondence between 10 time ranges and 10 histogram intervals.

[0081] In practical applications, the signal conversion module converts time data to the digital processing module. Therefore, the histogram intervals usually correspond to time ranges.

[0082] S102, the digital processing module divides the information storage space into multiple subspaces that correspond one-to-one with multiple histogram intervals.

[0083] For example, such as Figure 9As shown, assuming there are 10 histogram intervals, the information storage space is divided into 10 subspaces. Subspace 0 corresponds to histogram interval 0, subspace 1 corresponds to histogram interval 1, subspace 2 corresponds to histogram interval 2, subspace 3 corresponds to histogram interval 3, subspace 4 corresponds to histogram interval 4, subspace 5 corresponds to histogram interval 5, subspace 6 corresponds to histogram interval 6, subspace 7 corresponds to histogram interval 7, subspace 8 corresponds to histogram interval 8, and subspace 9 corresponds to histogram interval 9.

[0084] In some embodiments, the digital processing module allocates a corresponding storage address for each signal conversion module within each subspace.

[0085] Taking the aforementioned 10 subspaces as an example, if the radar system contains 1000 signal conversion modules, then each subspace is divided into 1000 different storage addresses, with each storage address corresponding to a signal conversion module. For instance, the digital processing module records the number of data points falling into the range 0-x1 measured by signal storage module 1, and stores this number in the storage address corresponding to signal storage module 1 in subspace 0. As another example, the digital processing module records the number of data points falling into the range x5-x6 measured by signal storage module n, and stores this number in the storage address corresponding to signal storage module n in subspace 5.

[0086] S103. The signal conversion module receives the pulse signal triggered by the ranging echo, converts the time difference between the moment the pulse signal is received and the start time of the current time flight window into digital signal data, and sends the digital signal data to the digital processing module.

[0087] S104. During any time flight window in the coarse measurement process, the digital processing module reads the number of digital signal data corresponding to all signal conversion modules stored in each subspace of the storage space in ascending order of the coarse data range matched by the corresponding histogram interval.

[0088] For example, based on the above example, within a certain time flight window during the coarse measurement process, the digital processing module sequentially reads the number of digital signal data corresponding to all signal conversion modules stored in the subspace corresponding to each histogram interval, in the order of histogram interval 0 to histogram interval 9.

[0089] In some embodiments, the radar system emits a preset number of ranging lasers during a single ranging operation. That is, a single ranging operation includes a preset number of time windows. The user pre-sets the number of time windows corresponding to the coarse measurement process as a first preset number, and the number of time windows corresponding to the fine measurement process as a second preset number. The sum of the first and second preset numbers is the preset number. For example, if the radar system needs to emit 1000 ranging lasers to obtain a depth image, the user can set the first 100 lasers as the coarse measurement process and the last 900 as the fine measurement process.

[0090] S105. After receiving the digital signal data transmitted by each signal conversion module, the digital processing module updates the number of digital signal data transmitted by the signal conversion module that falls into the histogram interval based on the histogram interval into which the digital signal data falls, and the number of digital signal data corresponding to the signal conversion module within the histogram interval. The updated number of digital signal data transmitted by the signal conversion module that falls into each histogram interval is then stored in the storage location matching the signal conversion module in the subspace corresponding to the histogram interval.

[0091] The subspace includes storage locations corresponding to each signal conversion module.

[0092] In some embodiments, the digital processing module updates the number of digital signal data transmitted by the signal conversion module that falls into the histogram interval based on the histogram interval into which the digital signal data falls and the number of digital signal data corresponding to the signal conversion module within the histogram interval. Specifically, for each histogram interval, if the digital signal data transmitted by the signal conversion module falls into the histogram interval, the digital processing module increments the number of digital signal data corresponding to the signal conversion module within that histogram interval by 1 to obtain the updated number of digital signal data transmitted by the signal conversion module that falls into the histogram interval.

[0093] For example, if the digital processing module receives a digital signal data transmitted by the signal conversion module 1, and this digital signal data falls into the coarse measurement interval 1, then the digital processing module reads the quantity stored in the storage address corresponding to the signal conversion module 1 in the subspace 1. If the quantity is 56, then the digital processing module obtains that the updated quantity of digital signal data transmitted by the signal conversion module 1 that falls into the histogram interval 1 is 57, and finally stores 57 in the original storage location of 56.

[0094] In related technologies, a single TDC will send measurement events indefinitely within N time slices (with pixel dead time as the step) during a single measurement time flight window, such as... Figure 10 As shown, each pixel unit has its own independent histogram address index logic and histogram data storage space in its corresponding TDC. When the parallelism of the TDC is high, it consumes more processing resources.

[0095] Since the reception of digital signal data is time-ordered, when receiving digital signal data within a coarse data range, multiple signal conversion modules will transmit digital signal data within that coarse data range. During storage, the quantity corresponding to the first received digital signal data is stored first. In this application, the information storage space is divided into subspaces using histogram intervals. Data stored in the subspaces corresponding to each histogram interval is read sequentially in ascending order of the coarse data range corresponding to the histogram interval. That is, the quantity corresponding to the first received coarse data range is read first, so the data corresponding to the first received digital signal data can be updated before storage. At this point, it is only necessary for the processing speed of the digital processing module to be equal to that of the signal conversion module. This process utilizes the time correlation of digital signal data transmission, mitigating the complexity of histogram update logic caused by the randomness of the transmission times of digital signal data by different signal conversion modules. The transmission of digital signal data by each signal conversion module during the coarse measurement process is considered as N independent binary distributed events. Multiple signal conversion modules can be viewed as corresponding to multiple time-correlated N independent binary events. Therefore, the corresponding histogram generation logic can use the same simple logic. Furthermore, due to the temporal order of digital signal data transmission, only simple counter logic is needed to complete the histogram reading and updating. Figure 11 The histogram update logic shown saves the logical resources required for histogram generation, reading, and updating. Furthermore, by integrating time correlation with the receiving order of digital signal data, it eliminates the need to store the digital signal data transmitted by the signal conversion module during the coarse measurement process; instead, it stores the quantity of digital signal data, thus reducing the storage resources required for the quantity compared to the storage resources required for the digital signal data itself.

[0096] In some embodiments, for each signal conversion module, after the coarse measurement process of the first preset number of time-flying windows is completed, the digital processing module obtains a coarse histogram corresponding to the signal conversion module; the digital processing module performs peak finding processing on the coarse histogram to obtain the coarse histogram interval corresponding to the peak value of the coarse histogram; the digital processing module divides the coarse data range corresponding to the coarse histogram interval into a preset number of fine data ranges; the digital processing module changes the coarse data range corresponding to each histogram interval into a corresponding fine data range; the digital processing module performs a fine measurement process of the second preset number of time-flying windows to obtain a fine histogram corresponding to the signal conversion module; the digital processing module performs peak finding processing on the fine histogram to obtain the fine histogram interval corresponding to the peak value of the fine histogram; the digital processing module combines the coarse data range corresponding to the coarse histogram interval and the fine data range corresponding to the fine histogram interval to obtain the measurement distance corresponding to the signal conversion module; the digital processing module combines the measurement distances corresponding to each signal conversion module to output the depth image measured by the radar system.

[0097] Specifically, one signal conversion module corresponds to one pixel unit, and the measurement distance corresponding to the signal conversion module is the measurement distance corresponding to the pixel unit corresponding to that signal conversion module. Finally, by combining the measurement distances corresponding to each pixel unit, the depth image measured by the radar system can be obtained.

[0098] For example, the digital processing module divides the data into 10 coarse data ranges. After 100 time windows have passed, the digital processing module counts the number of digital signal data in the histogram interval 5 corresponding to the signal conversion module 1. Then, the digital processing module can determine that the coarse data range corresponding to the histogram interval 5 is 50-60 meters, that is, the coarse histogram interval is 50-60 meters. The digital processing module divides the coarse data range corresponding to the coarse histogram interval into 10 fine data ranges: 50-51 meters, 51-52 meters, 52-53 meters, 53-54 meters, 54-55 meters, 55-56 meters, 56-57 meters, 57-58 meters, 58-59 meters, and 59-60 meters. The module then determines a one-to-one correspondence between the histogram intervals 0-9 and the fine data ranges 50-51 meters, 51-52 meters, 52-53 meters, 53-54 meters, 54-55 meters, 55-56 meters, 56-57 meters, 57-58 meters, 58-59 meters, and 59-60 meters. After the time-flying window of 900 fine measurement processes is completed, the digital processing module identifies the histogram interval corresponding to the fine data range with the most digital signal data; this is the fine histogram interval. If the fine histogram interval is histogram interval 3, then the fine data range corresponding to the fine histogram interval is 52-53 meters. Combined with the coarse data range corresponding to the coarse histogram interval, which is 50-60 meters, it can be determined that the measurement distance corresponding to the pixel unit of the signal conversion module 1 is 52 meters.

[0099] In this way, the histogram update logic in the fine measurement process reuses the histogram update logic in the coarse measurement process, so the logical resources occupied by the fine measurement process will not increase compared to the coarse measurement process. When switching between the coarse and fine measurement processes, the coarse data range corresponding to each histogram interval will be changed to a corresponding fine data range. The number of histogram intervals is fixed, and the maximum storage resources corresponding to each histogram interval are also fixed. This application does not need to increase the number of histogram intervals, and therefore will not increase the storage resources corresponding to the histogram intervals, ultimately reducing the storage resources occupied by the information storage space used to store histogram-related data.

[0100] In some embodiments, after the coarse measurement process of the first preset number of time-flying windows is completed, the digital processing module obtains a coarse histogram corresponding to the signal conversion module. Specifically, this can be implemented as follows: the digital processing module determines that the range of digital signal data transmitted by the signal conversion module during the coarse measurement process is the full range, and sends indication information indicating the full range to each signal conversion module; the signal conversion module receives the indication information and transmits all digital signal data converted by the signal conversion module to the digital processing module within each time-flying window of the coarse measurement process; after the coarse measurement process of the first preset number of time-flying windows is completed, the digital processing module generates a coarse histogram corresponding to the signal conversion module based on the number of digital signal data stored in the storage locations matching the signal conversion modules in each subspace of the storage space.

[0101] The term "full range" refers to the signal conversion module transmitting all received laser echoes as digital signal data to the digital output module.

[0102] For example, after 100 time windows, taking signal conversion module 1 as an example, the digital processing module counts the number of digital signal data falling into histogram interval 0 as 5, the number of digital signal data falling into histogram interval 1 as 7, the number of digital signal data falling into histogram interval 2 as 9, the number of digital signal data falling into histogram interval 3 as 12, the number of digital signal data falling into histogram interval 4 as 27, the number of digital signal data falling into histogram interval 5 as 60, the number of digital signal data falling into histogram interval 6 as 30, the number of digital signal data falling into histogram interval 7 as 36, the number of digital signal data falling into histogram interval 8 as 26, and the number of digital signal data falling into histogram interval 9 as 16. The digital processing module can then obtain the coarse histogram corresponding to signal conversion module 1.

[0103] In this way, the digital processing module receives digital signal data from the full range during the coarse measurement process. Since the amount of data is large, by storing the number of digital signal data that fall into each histogram interval transmitted by each signal conversion module, the workload of counting the number of digital signal data that fall into each histogram interval is reduced. At the end of the coarse measurement process, the coarse histogram corresponding to each signal conversion module can be obtained quickly.

[0104] In some embodiments, after the coarse measurement process of the first preset number of time-flying windows is completed, the digital processing module deletes the digital signal data stored in the storage space during the coarse measurement process; the digital processing module performs a fine measurement process of the second preset number of time-flying windows to obtain a fine histogram corresponding to the signal conversion module. Specifically, this can be implemented as follows: the digital processing module sends the coarse data range corresponding to the coarse histogram interval to the corresponding signal conversion module; the signal conversion module receives the coarse data range corresponding to the coarse histogram interval sent by the digital processing module, filters out the digital signal data that does not fall within the coarse data range corresponding to the coarse histogram interval, and transmits the digital signal data that falls within the coarse data range corresponding to the coarse histogram interval to the digital processing module; the digital processing module receives the digital signal data that falls within the coarse data range corresponding to the coarse histogram interval transmitted by the signal conversion module; after the fine measurement process of the second preset number of time-flying windows is completed, the digital processing module generates a fine histogram corresponding to the signal conversion module based on the digital signal data stored in the storage location corresponding to the signal conversion module in each histogram interval in the storage space.

[0105] For example, the 900 time windows following the completion of the 100 time windows in the coarse measurement process constitute the fine measurement process. Digital signal data that does not fall within the coarse data range corresponding to the coarse histogram interval will not be transmitted to the digital processing module. After the detailed measurement process of 900 time flight windows is completed, taking signal conversion module 1 as an example, the digital processing module counts the number of digital signal data falling into histogram interval 0 as 21, the number of digital signal data falling into histogram interval 1 as 65, the number of digital signal data falling into histogram interval 2 as 105, the number of digital signal data falling into histogram interval 3 as 62, the number of digital signal data falling into histogram interval 4 as 52, the number of digital signal data falling into histogram interval 5 as 58, the number of digital signal data falling into histogram interval 6 as 45, the number of digital signal data falling into histogram interval 7 as 39, the number of digital signal data falling into histogram interval 8 as 26, and the number of digital signal data falling into histogram interval 9 as 15. Based on this, the digital processing module can obtain the detailed histogram corresponding to signal conversion module 1.

[0106] In this way, after the coarse measurement process is completed and a coarse histogram interval is obtained, the amount of digital signal data recorded during the coarse measurement process is no longer needed. After deleting the amount of digital signal data stored in the storage space during the coarse measurement process, some storage space can be saved. The digital signal data received during the fine measurement process is still stored in the storage space corresponding to the coarse measurement process. There is no separate storage space set up for the fine measurement process and the coarse measurement process. The storage resources occupied when storing histogram-related data are less.

[0107] In some embodiments, the digital processing module receives digital signal data transmitted by the signal conversion module that falls within the coarse data range corresponding to the coarse histogram interval. Specifically, this can be implemented as follows: the digital processing module divides the time flight window into a preset number of time slices, with one time slice corresponding to one histogram interval, and one time slice being less than or equal to one pixel dead time; the digital processing module determines the target time slice corresponding to the coarse histogram interval; and within the target time slice, the digital processing module receives digital signal data transmitted by the signal conversion module that falls within the coarse data range corresponding to the coarse histogram interval.

[0108] Specifically, after a pixel unit receives the laser echo from the ranging laser, it will be unable to work for a period of time. The pixel unit needs to be charged and discharged to activate it. This is what is generally referred to as the pixel dead time.

[0109] Figure 12 The diagram illustrates the histogram update process for the fine measurement procedure. Since a time slice is less than or equal to one pixel dead time, at most one digital signal data can be received within a time slice. The number of time slices within a time flight window is the same as the number of histogram intervals. This determines the target time slice corresponding to the coarse histogram interval, which in turn determines the target time slice corresponding to the coarse data range of the coarse histogram interval. Through the filtering of target time slices, within one time flight window of the fine measurement procedure, a signal conversion module will transmit at most one digital signal data, eliminating data irrelevant to the fine measurement procedure and reducing the workload of the digital processing module.

[0110] Based on the above embodiments, within any time flight window of the fine measurement process, the digital processing module sequentially reads the number of digital signal data in each histogram interval stored in the storage location corresponding to each signal conversion module in the storage space, according to the pre-set arrangement order of the signal conversion modules.

[0111] For example, based on the above example, within a certain time flight window during the fine measurement process, the digital processing module reads the number of digital signal data in each histogram interval stored in the storage location corresponding to each signal conversion module in the information storage module in the order of signal conversion module 1 to signal conversion module 1000.

[0112] Since a signal conversion module can only transmit one digital signal data within a time flight window during the fine measurement process, the amount of data is greatly reduced. The workload required by the digital processing module is not much different whether the data is read in the order of the histogram intervals or in the order of the signal conversion modules. Therefore, during the fine measurement process, the digital processing module reads the number of digital signal data in each histogram interval stored in the storage location corresponding to each signal conversion module in the storage space according to the pre-set arrangement order of the signal conversion modules. In this way, the digital signal data can be stored one-to-one in the storage location corresponding to the signal conversion module.

[0113] In some embodiments, during the coarse measurement process, if the digital processing module receives digital signal data transmitted by the signal conversion module within the first time slice, it records a first value corresponding to the first time slice; if it does not receive digital signal data transmitted by the signal conversion module within the first time slice, it records a second value corresponding to the first time slice; the first time slice is any time slice within the time flight window; the digital processing module updates the number of digital signal data transmitted by the signal conversion module that falls into the histogram interval based on the histogram interval into which the digital signal data falls, and the number of digital signal data corresponding to the signal conversion module within the histogram interval read from the histogram module. Specifically, this can be implemented as follows: the digital processing module determines the histogram interval corresponding to the first time slice; the digital processing module adds the first value or the second value corresponding to the first time slice to the number of digital signal data transmitted by the signal conversion module within the histogram interval corresponding to the first time slice read from the histogram module, to obtain the updated number of digital signal data transmitted by the signal conversion module that falls into the histogram interval.

[0114] Specifically, the first value can be 1, and the second value can be 0.

[0115] For example, within a certain time flight window during the coarse measurement process, there are a total of 10 time slices. The digital processing module records the data string corresponding to the signal conversion module 1 within this time flight window as 1001010101, indicating that the signal conversion module 1 received laser echoes in the first, fourth, sixth, eighth, and tenth time slices within this time flight window and transmitted digital signal data to the digital conversion module. No laser echoes were received in the other time slices. Each time slice corresponds to a data range. If the first to tenth time slices correspond one-to-one with the first to tenth coarse data ranges, and assuming that before this time flight window, the signal conversion module 1 has the following data in its information storage space: 5 digital signal data falling into histogram interval 0, 7 falling into histogram interval 1, 9 falling into histogram interval 2, 12 falling into histogram interval 3, 27 falling into histogram interval 4, 60 falling into histogram interval 5, 30 falling into histogram interval 6, 36 falling into histogram interval 7, 26 falling into histogram interval 8, and 16 falling into histogram interval 9, then the digital processing module updates the data within this time flight window. When dealing with the corresponding histogram data, the following data is used: 5+1, 0+7, 0+9, 1+12, 0+27, 1+60, 0+30, 1+36, 0+26, 1+16. The number of digital signal data corresponding to each coarse histogram interval updated by the digital processing module after this time window is as follows: 6 digital signal data fall into histogram interval 0; 7 fall into histogram interval 1; 9 fall into histogram interval 2; 13 fall into histogram interval 3; 27 fall into histogram interval 4; 61 fall into histogram interval 5; 30 fall into histogram interval 6; 37 fall into histogram interval 7; 26 fall into histogram interval 8; and 17 fall into histogram interval 9.

[0116] In practical applications, the data string corresponding to the signal conversion module within a certain time flight window can be first stored in an asynchronous first-in-first-out (FIFO) buffer. The digital processing module then reads the data string from the asynchronous FIFO and adds it to the number of digital signal data read from the information storage space. The summed number is then stored in the information storage space to complete the histogram update after a time flight window of the coarse measurement process ends.

[0117] Since the signal conversion module may transmit a large amount of digital signal data in each time flight window of the coarse measurement process, the first and second values ​​can be used to quickly record whether the signal conversion module has received the laser echo, which occupies less storage resources. When updating the histogram, the digital processing module only needs to perform a simple summation, which also requires less logic resources.

[0118] In some embodiments, the digital processing module stores the digital signal data received during the fine measurement process in the storage location corresponding to the signal conversion module.

[0119] Based on the above description, it can be seen that at most one digital signal data can be received in the time flight window of the fine measurement process. Since the data volume is not large, the received digital signal data can be stored directly, reducing the process of converting it into the first or second value. This will not increase the storage resources occupied, nor will it increase the logical resources required for the processing.

[0120] Figure 8 The technical solution presented offers at least the following advantages: All digital signal data transmitted by the signal conversion modules in the radar system is stored within the information storage space, eliminating the need for separate independent storage spaces for each signal conversion module and saving actual circuit area. The subspaces within the information storage space correspond one-to-one with histogram intervals. When the digital processing module reads data from the storage space, it sequentially reads the data in each subspace according to the order of the coarse data range matched by the corresponding histogram interval, from smallest to largest. That is, for a radar system using a DTOF radar array for ranging, the number of histogram intervals divided corresponds to the number of times the digital processing module reads the subspace within a single time window. Compared to reading the independent storage spaces corresponding to each signal conversion module separately, the number of histogram intervals is far less than the number of signal conversion modules. Therefore, the number of times the digital processing module reads data is significantly reduced, correspondingly saving processing time for histogram data. Since radar ranging always receives the echo reflected from the nearest object first, meaning the digital processing module always receives the digital signal data corresponding to the shortest time difference transmitted by each signal conversion module first, the data in each subspace is read sequentially according to the coarse data range matched by the corresponding histogram interval, taking into account the time order of data storage. Therefore, a single read operation within the information storage space within a single time flight window is sufficient to read all the data stored in the information storage space, eliminating the need for secondary data readings and reducing the time spent on repeated data retrieval. Thus, under high repetition rate measurements, the histogram processing method of this application does not require increasing the area of ​​the histogram generation circuit and saves histogram processing time, meeting the user's requirements regarding the actual circuit area occupied by the information storage space and the histogram processing time.

[0121] The following describes the histogram generation process in this application from the perspective of the overall workflow:

[0122] like Figure 13 As shown, the coarse measurement process is first performed. The ranging laser is sent at the set frequency. At this time, the TDC gated time window is set to the full range and no measurement event gating is performed.

[0123] The TDC counting starts simultaneously with laser emission. Within the effective time flight window, the pixel unit receives the laser echo, and the TDC quantizes the time difference between the time of the pixel unit's output pulse signal (vld value) and the emission time of the ranging laser (clk value) into digital signal data. All TDCs in the entire array system are simultaneously and in parallel in this working state until the time flight window ends.

[0124] Within the time flight window, when the TDC writes synchronous window data to the asynchronous FIFO in the digital processing module, the digital processing module sequentially reads the subspace corresponding to each histogram interval in the information storage space, aligns the data in the FIFO with the data read by the digital processing module, adds the corresponding data (if it falls into a certain histogram interval, the data in this histogram interval is incremented by 1), and then writes it back to the corresponding RAM address. After the data stored in the FIFO within the time flight window is emptied, a complete coarse histogram update is completed.

[0125] After updating the coarse histogram for the first preset number of times (that is, after the time flight window for the first preset number of times ends), a complete coarse histogram is obtained. Peak finding processing is performed on the coarse histogram to obtain the peak value of the coarse histogram, that is, the coarse histogram interval. Then, the data stored in the coarse measurement process is deleted, and the coarse histogram interval corresponding to each TDC is back-annotated and output back to the TDC, waiting to start the fine measurement process.

[0126] During the fine measurement process, TDC will determine the time window position to be opened based on the coarse histogram interval returned by the digital processing module after the coarse measurement process is completed. TDC only obtains the timestamp information within the gated time window, and then stably transmits the obtained data to the digital processing module. The digital processing module performs fine histogram statistics accordingly.

[0127] After updating the fine histogram for the second preset number of times (that is, after the time flight window for the second preset number of times ends), a complete fine histogram is constructed; then a series of processes such as fine histogram peak finding and filtering are performed to finally obtain the peak value of the fine histogram, that is, the interval position information of the fine histogram, and delete the data stored during the fine measurement process;

[0128] By merging the coarse and fine histogram intervals, the complete target location information data is obtained. Combining the target location information data corresponding to each pixel unit yields the depth image measured by the radar system.

[0129] The foregoing primarily describes the solutions provided by the embodiments of this application from a methodological perspective. To achieve the aforementioned functions, it includes corresponding hardware structures and / or software modules for executing each function. Those skilled in the art should readily recognize that, in conjunction with the units and algorithm steps of the various examples described in the embodiments disclosed herein, this application can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed in hardware or by computer software driving hardware depends on the specific application and design constraints of the technical solution. Those skilled in the art may use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0130] Another embodiment of this application provides a radar system, including: a processor; a memory; wherein the memory is used to store computer program code, the computer program code including computer instructions, and when the processor executes the computer instructions, the radar system performs the various steps of the radar system described above.

[0131] Another embodiment of this application provides a computer-readable storage medium storing computer instructions that, when executed on a computer, cause the computer to perform the various steps of the radar system in the method flow shown in the above method embodiment.

[0132] In another embodiment of this application, a computer program product is also provided, which includes computer instructions that, when executed on a computer, cause the computer to perform the various steps of the radar system in the method flow shown in the above method embodiment.

[0133] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented using software programs, implementation can be, in whole or in part, in the form of a computer program product. This computer program product includes one or more computer instructions. When these computer instructions are loaded and executed on a computer, all or part of the flow or function according to the embodiments of this application is generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device containing one or more servers, data centers, etc., that can be integrated with the medium. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), etc.

[0134] The above description is merely a specific embodiment of this application. Any variations or substitutions conceived by those skilled in the art based on the specific embodiments provided in this application should be covered within the protection scope of this application.

Claims

1. A histogram processing method based on a surface-array DTOF radar, characterized in that, The method is applied to a radar system, which includes multiple signal conversion modules and a digital processing module; the method includes: The digital processing module divides a preset number of histogram intervals and a preset number of coarse data ranges based on the ranging range of the radar system, and establishes a correspondence between the preset number of histogram intervals and the preset number of coarse data ranges, with one histogram interval corresponding to one coarse data range. The digital processing module divides the information storage space into multiple subspaces that correspond one-to-one with multiple histogram intervals; The signal conversion module receives the pulse signal triggered by the ranging echo, converts the time difference between the moment the pulse signal is received and the start time of the current time flight window into digital signal data, and sends the digital signal data to the digital processing module. During any time flight window in the coarse measurement process, the digital processing module reads the number of digital signal data corresponding to all signal conversion modules stored in each subspace of the storage space in ascending order of the coarse data range matched by the corresponding histogram interval; After receiving the digital signal data transmitted by each of the signal conversion modules, the digital processing module updates the number of digital signal data transmitted by each signal conversion module that falls within the histogram interval based on the histogram interval into which the digital signal data falls, and the number of digital signal data corresponding to each signal conversion module within the histogram interval. The updated number of digital signal data transmitted by each signal conversion module that falls within each of the histogram intervals is then stored in a storage location in the subspace corresponding to the histogram interval that matches the storage location of each signal conversion module. The subspace includes storage locations corresponding to each of the signal conversion modules.

2. The method according to claim 1, characterized in that, The method further includes: Within any time flight window of the fine measurement process, the digital processing module sequentially reads the number of digital signal data in each histogram interval stored in the storage location corresponding to each signal conversion module in the storage space, according to the pre-set arrangement order of the signal processing modules.

3. The method according to claim 2, characterized in that, The method further includes: For each of the signal conversion modules, after the coarse measurement process of the first preset number of time flight windows is completed, the digital processing module obtains the coarse histogram corresponding to the signal conversion module. The digital processing module performs peak finding processing on the coarse histogram to obtain the coarse histogram interval corresponding to the peak value of the coarse histogram. The digital processing module divides the coarse data range corresponding to the coarse histogram interval into the preset number of fine data ranges. The digital processing module changes the coarse data range corresponding to each histogram interval to a corresponding fine data range. The digital processing module performs a second preset number of time flight windows for fine measurement, and obtains the fine histogram corresponding to the signal conversion module; The digital processing module performs peak finding processing on the thin histogram to obtain the thin histogram interval corresponding to the peak value of the thin histogram; The digital processing module combines the coarse data range corresponding to the coarse histogram interval and the fine data range corresponding to the fine histogram interval to obtain the measurement distance corresponding to the signal conversion module. The digital processing module combines the measurement distances corresponding to each of the signal conversion modules to output the depth image measured by the radar system.

4. The method according to claim 3, characterized in that, After the coarse measurement process of the first preset number of time windows is completed, the digital processing module obtains the coarse histogram corresponding to the signal conversion module, including: The digital processing module determines that the range of digital signal data transmitted by the signal conversion module during the coarse measurement process is the full range, and sends the indication information used to indicate the full range to each of the signal conversion modules; The signal conversion module receives the indication information and transmits all digital signal data converted by the signal conversion module to the digital processing module within each time flight window of the coarse measurement process. After the coarse measurement process of the first preset number of time flight windows is completed, the digital processing module generates a coarse histogram corresponding to the signal conversion module based on the number of digital signal data stored in the storage locations that match the signal conversion module in each subspace of the storage space.

5. The method according to claim 3, characterized in that, After the coarse measurement process of the first preset number of time flight windows is completed, the method further includes: The digital processing module deletes the digital signal data stored in the storage space during the coarse measurement process; The digital processing module performs a second preset number of time-flying windows of fine measurement to obtain the fine histogram corresponding to the signal conversion module, including: The digital processing module sends the coarse data range corresponding to the coarse histogram interval to the corresponding signal conversion module. The signal conversion module receives the coarse data range corresponding to the coarse histogram interval sent by the digital processing module, filters out digital signal data that does not fall within the coarse data range corresponding to the coarse histogram interval, and transmits the digital signal data that falls within the coarse data range corresponding to the coarse histogram interval to the digital processing module. The digital processing module receives digital signal data transmitted by the signal conversion module that falls within the coarse data range corresponding to the coarse histogram interval; After the fine measurement process of the second preset number of time flight windows is completed, the digital processing module generates a fine histogram corresponding to the signal conversion module based on the digital signal data stored in the storage location corresponding to the signal conversion module in each histogram interval in the storage space.

6. The method according to claim 5, characterized in that, The digital processing module receives digital signal data transmitted by the signal conversion module that falls within the coarse data range corresponding to the coarse histogram interval, including: The digital processing module divides the time flight window into the preset number of time slices, with one time slice corresponding to one histogram interval, and one time slice being less than or equal to one pixel dead time. The digital processing module determines the target time slice corresponding to the coarse histogram interval; The digital processing module receives digital signal data transmitted by the signal conversion module within the coarse data range corresponding to the coarse histogram interval during the target time slice.

7. The method according to claim 6, characterized in that, The method further includes: During the coarse measurement process, if the digital processing module receives digital signal data transmitted by the signal conversion module within the first time slice, it records a first value corresponding to the first time slice; if it does not receive digital signal data transmitted by the signal conversion module within the first time slice, it records a second value corresponding to the first time slice; the first time slice is any time slice within the time flight window; The digital processing module updates the number of digital signal data transmitted by the signal conversion module that falls within the histogram interval based on the histogram interval into which the digital signal data falls, and the number of digital signal data corresponding to the signal conversion module within the histogram interval read from the histogram module. This includes: The digital processing module determines the histogram interval corresponding to the first time slice; The digital processing module adds the first or second value corresponding to the first time slice to the number of digital signal data read by the signal conversion module within the histogram interval corresponding to the first time slice, to obtain the updated number of digital signal data transmitted by the signal conversion module that falls into the histogram interval.

8. The method according to claim 6, characterized in that, During the detailed measurement process, the digital processing module updates the number of digital signal data transmitted by the signal conversion module that falls within the histogram interval based on the histogram interval into which the digital signal data falls, and the number of digital signal data corresponding to the signal conversion module within the histogram interval read from the signal conversion module. This includes: For each histogram interval, if the digital signal data transmitted by the signal conversion module falls into the histogram interval, the digital processing module will increment the number of digital signal data corresponding to the signal conversion module in the histogram interval by 1 to obtain the updated number of digital signal data transmitted by the signal conversion module that falls into the histogram interval.

9. A radar system, characterized in that, The radar system includes a laser emitting module, an echo receiving module, multiple signal conversion modules, and a digital processing module; The laser emitting module is used to emit ranging lasers at a preset frequency; The echo receiving module includes multiple pixel units, and one pixel unit corresponds to one signal conversion module; The pixel unit is used to receive the ranging echo within a time flight window after the laser emitting module emits a ranging laser once, and to send a pulse signal to the corresponding signal conversion module when the ranging echo is received. The signal conversion module is used to record the time when the pulse signal sent by the corresponding pixel unit is received, convert the time difference between the time when the pulse signal sent by the corresponding pixel unit is received and the start time of the current time flight window into digital signal data, and send the digital signal data to the digital processing module. The digital processing module is used to divide a preset number of histogram intervals and to divide a preset number of coarse data ranges based on the ranging range of the radar system, and to establish a correspondence between the preset number of histogram intervals and the preset number of coarse data ranges, wherein one histogram interval corresponds to one coarse data range. The digital processing module is used to divide the information storage space into multiple subspaces that correspond one-to-one with multiple histogram intervals; During any time flight window in the coarse measurement process, the digital processing module is used to read the number of digital signal data corresponding to all signal conversion modules stored in all subspaces of the storage space in ascending order of the coarse data range matched by the corresponding histogram interval; The digital processing module is used to, after receiving digital signal data transmitted by each of the signal conversion modules, update the number of digital signal data transmitted by the signal conversion module that falls into the histogram interval based on the histogram interval into which the digital signal data falls, and the number of digital signal data corresponding to the signal conversion module within the histogram interval read out. The updated number of digital signal data transmitted by the signal conversion module that falls into each of the histogram intervals is then stored in a storage location in the subspace corresponding to the histogram interval that matches the storage location of the signal conversion module. The subspace includes storage locations corresponding to each of the signal conversion modules.

10. A radar system, characterized in that, include: processor; Memory; The memory is used to store computer program code, which includes computer instructions. When the processor executes the computer instructions, the radar system executes the histogram processing method based on the area array DTOF radar as described in any one of claims 1-8.

11. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when executed on a computer, cause the computer to perform the histogram processing method based on a surface array DTOF radar as described in any one of claims 1-8.

Images