Multi-working-mode single photon avalanche diode reconfigurable receiving system and reconfiguration method

Abstract

The invention relates to the technical field of perception imaging, and discloses a multi-working-mode single photon avalanche diode reconfigurable receiving system and a reconstruction method, and the system comprises at least one reconfigurable pixel module, at least one multiplexer, at least one signal processing circuit, a working mode / reconstruction control circuit, and a data processing module. The working mode / reconfiguration control circuit is used for selecting a short-distance working mode and a long-distance working mode; the multiplexer has a short-distance working mode and a long-distance working mode; and the data processing module is used for rearranging and combining the input distance information quantification result based on the working mode to obtain complete imaging information. According to the invention, the problem that a data processing module in the prior art is used for rearranging and recombining the input distance information quantification result based on a working mode to obtain complete imaging information is solved, and the device has the characteristics of improving the photosensitive area and quickly and accurately outputting the detection result.

Description

Technical Field

[0001] The present invention relates to the field of perceptual imaging technology, and more specifically, to a single-photon avalanche diode reconfigurable receiving system with multiple working modes and a reconstruction method. Background Art

[0002] LiDAR sensing imaging technology using single photon avalanche diodes (SPADs) plays an important role in industrial robots, medical treatment, self-driving cars and other application fields. Figure 1 As shown, the SPAD-based lidar perception imaging receiving system detects the distance between objects by actively emitting a laser beam to the target object and detecting the flight time of the reflected beam.

[0003] SPADs operating in Geiger mode, where the reverse bias voltage is higher than the avalanche breakdown voltage, can theoretically induce an avalanche effect under a strong electric field with only a small number of incident photons, and have a very high photoelectric conversion gain. Figure 2 As shown, in the SPAD-based lidar perception imaging receiving system, in order to increase the photosensitivity area, detection probability and reduce the loss of effective signals caused by the SPAD being falsely triggered by noise and entering the dead zone, multiple SPADs are usually combined as a group of macro pixels and connected to subsequent signal processing circuits.

[0004] In the existing SPAD-based LiDAR perception imaging system, the way SPADs form macro-pixel units is fixed, that is, each macro-pixel unit is composed of several fixed SPADs. Faced with the demand for large-array high-resolution depth perception imaging, the method of directly increasing the number of pixels in proportion is not only expensive, but also faces problems such as poor pixel consistency caused by large-area distribution of SPADs.

[0005] like Figure 2 As shown, the prior art has a pixel reconfiguration technology that uses the principle of time-division multiplexing to change the physical position of the SPAD that constitutes the macro pixel, thereby improving the imaging resolution without increasing the circuit area.

[0006] However, the existing technology has the problem of being unable to quickly switch the receiving mode based on the detection target. Therefore, how to invent a reconfigurable receiving system that can switch the receiving mode based on demand is a technical problem that urgently needs to be solved in this technical field. Summary of the invention

[0007] In order to solve the problem in the prior art that the receiving mode cannot be quickly switched based on the detection target, the present invention provides a single-photon avalanche diode reconfigurable receiving system and a reconstruction method with multiple working modes, which has the characteristics of increasing the photosensitivity area and quickly and accurately outputting the detection results.

[0008] In order to achieve the above-mentioned purpose of the present invention, the technical scheme adopted is as follows: A single-photon avalanche diode reconfigurable receiving system with multiple working modes, comprising at least one reconfigurable pixel module, at least one multiplexer, at least one signal processing circuit, a working mode / reconstruction control circuit, and a data processing module; The reconfigurable pixel module, the multiplexer, the signal processing circuit, and the data processing module are electrically connected in sequence; the output end of the working mode / reconfiguration control circuit is electrically connected to the gating control end of the multiplexer, the signal processing circuit, and the data processing module; The reconfigurable pixel module is composed of a number of single-photon avalanche diodes SPAD and their corresponding front-end circuits, and is used to receive the reflected light beam; The multiplexer is used to select the SPAD of the corresponding reconfigurable pixel module and its corresponding front-end circuit to combine or switch to form a corresponding macro pixel unit, and input the output of each macro pixel unit into a signal processing circuit; The signal processing circuit is used to process and quantize the output of each macro pixel unit to obtain the corresponding distance information quantization result; The working mode / reconstruction control circuit is used to select the working mode and output the corresponding reconstruction and working mode pulse signals; The data processing module is used to rearrange and combine the input distance information quantization results based on the working mode to obtain complete imaging information.

[0009] Preferably, the multiplexer has short-range and long-range working modes; in the short-range working mode, the multiplexer uses a time-division multiplexing method to reconstruct the SPAD of the corresponding reconfigurable pixel module and its corresponding front-end circuit to obtain a macro-pixel unit; in the long-range working mode, the multiplexer combines all SPADs and their corresponding front-end circuits in the corresponding reconfigurable pixel module into a macro-pixel unit; the working mode / reconstruction control circuit is used to select either the short-range working mode or the long-range working mode.

[0010] Further, specifically, each reconfigurable pixel module corresponds to a signal processing circuit; and each reconfigurable pixel module is correspondingly connected to at least one multiplexer.

[0011] Furthermore, the reconfigurable pixel module is composed of K SPADs (m1×m2) and a front-end circuit corresponding to each SPAD.

[0012] Further, in the near - range working mode, the macro - pixel unit of the multiplexer combination consists of n1 x n2 SPADs and their corresponding front - end circuits, where n1 < m1 and n2 < m2; in the far - range working mode, the macro - pixel unit of the multiplexer combination consists of m1×m2 SPADs and their corresponding front - end circuits. Where K, m1, m2, n1, and n2 are all positive integers greater than 0.

[0013] Further, the signal processing circuit includes a cascaded noise filtering circuit and a time - to - digital converter circuit, which are used to process and quantize the output of the SPAD and its corresponding front - end circuit to obtain the final distance information quantization result; the noise filtering circuit adjusts the noise filtering threshold based on the pulse signal input by the working mode / reconstruction control circuit.

[0014] Further, in the near - range working mode, a time - division multiplexing method is used to reconstruct the SPAD and its corresponding front - end circuit of the corresponding reconfigurable pixel module. The specific steps are as follows: Define a time range, divide the time range into several time slots of fixed length, and each time slot allows different configurations and working modes to run; Within each time slot, different combinations of SPADs and their corresponding front - end circuits are selected through a multiplexer; During the selection and combination process, the hardware resources are multiplexed in different time slots to reduce complexity and power consumption; All SPADs are combined according to the time slots to obtain a macro - pixel unit composed of the reconstructed n1 x n2 SPADs and their corresponding front - end circuits.

[0015] Further, based on the selection of the working mode, the input distance information quantization result is rearranged and combined. Specifically: In the near - range working mode, due to the adoption of the time - division multiplexing reconfigurable mode, based on the predefined mapping relationship, the distance information quantization result data is rearranged according to the order of all macro - pixel units in the complete image, and the data block corresponding to each time slot is placed at the corresponding position in the final image to obtain a frame of complete imaging information; In the far - range working mode, the detection efficiency of the receiving end is detected. If the detection efficiency of the receiving end is not less than the set condition, all the distance information quantization results are directly arranged in order to obtain a frame of complete imaging information; when the detection efficiency of the receiving end is less than the set condition, the distance information quantization results corresponding to every several adjacent macro - pixel units are merged and processed, and then all the distance information quantization results are arranged in order to obtain a frame of complete imaging information.

[0016] Furthermore, the distance information quantization results corresponding to each number of adjacent macro-pixel units are merged and then all the merged distance information quantization results are arranged in order to obtain a frame of complete imaging information, specifically: the distance information quantization results corresponding to a single macro-pixel unit and its N adjacent macro-pixel units are processed by weighted filtering to obtain a merged distance information quantization result, where N is an arbitrary positive integer.

[0017] A method for reconstructing a single-photon avalanche diode reconfigurable receiving system with multiple working modes includes the following specific steps: Based on the distance of the target object to be detected, the working mode / reconfiguration control circuit is set to a short-distance working mode or a long-distance working mode; The working mode / reconstruction control circuit outputs reconstruction and working mode pulse signals to the multiplexer, the signal processing circuit, and the data processing module, and sets the multiplexer, the signal processing circuit, and the data processing module to the corresponding working mode; The multiplexer selects the SPAD of the corresponding reconfigurable pixel module and its corresponding front-end circuit to combine or switch to form a corresponding macro pixel unit based on its working mode; After all macro pixel units receive light signals, they are output to the signal processing circuit through the multiplexer; The distance information quantization result output by the signal processing circuit is input to the data processing module; the data processing module rearranges and combines the input distance information quantization result based on its working mode to obtain complete imaging information.

[0018] The beneficial effects of the present invention are as follows: The present invention proposes a single-photon avalanche diode reconfigurable receiving system and reconstruction method with multiple working modes, including at least one reconfigurable pixel module, at least one multiplexer, at least one signal processing circuit, a working mode / reconstruction control circuit, and a data processing module, wherein the working mode / reconstruction control circuit is used to select the working mode, and the multiplexer and the data processing module adjust their working modes based on the working mode selected by the working mode / reconstruction control circuit. They can quickly select a suitable receiving mode based on the detection environment, solving the problem in the prior art that the receiving mode cannot be quickly switched based on the detection target, and have the characteristics of increasing the photosensitive area and quickly and accurately outputting the detection results. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a working diagram of the existing SPAD-based lidar perception imaging system.

[0020] Figure 2 This is the block diagram of the receiving end system of the existing SPAD-based lidar perception imaging system.

[0021] Figure 3 The schematic diagram of a single-photon avalanche diode reconfigurable receiving system with multiple working modes is shown in FIG.

[0022] Figure 4 It is a logic block diagram of the working mode selection of the working mode / reconstruction control circuit.

[0023] Figure 5 It is a schematic diagram of the reconstruction of the close-range working mode of a single-photon avalanche diode reconfigurable receiving system with multiple working modes proposed by the present invention.

[0024] Figure 6 It is a schematic diagram of long-distance working mode reconstruction of a single-photon avalanche diode reconfigurable receiving system with multiple working modes proposed by the present invention.

[0025] Figure 7 This is a schematic diagram of a specific reconstruction of a close-range working mode of a single-photon avalanche diode reconfigurable receiving system with multiple working modes proposed by the present invention in Example 2.

[0026] Figure 8 This is a specific schematic diagram of the reconstruction of the long-distance working mode of a single-photon avalanche diode reconfigurable receiving system with multiple working modes proposed by the present invention in Example 2.

[0027] Fig. 9 It is a flow chart of a reconstruction method of a single-photon avalanche diode reconfigurable receiving system with multiple working modes according to the present invention. DETAILED DESCRIPTION

[0028] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] Example 1 like Figure 3 As shown, a single-photon avalanche diode reconfigurable receiving system with multiple working modes includes multiple reconfigurable pixel modules, multiple multiplexers, multiple signal processing circuits, working mode / reconstruction control circuits, and a data processing module; The reconfigurable pixel module, the multiplexer, the signal processing circuit, and the data processing module are electrically connected in sequence; the output end of the working mode / reconfiguration control circuit is electrically connected to the gating control end of the multiplexer, the signal processing circuit, and the data processing module; The reconfigurable pixel module is composed of several single-photon avalanche diodes (SPADs) and their corresponding front-end circuits, which are used to receive echo photon signals, convert them into digital pulse signals, and quench and reset the SPADs to ensure their stable operation. like Figure 4 , Figure 5 , Figure 6As shown, the multiplexer is used to select the SPAD of the corresponding reconfigurable pixel module and its corresponding front-end circuit to combine or switch to form a corresponding macro-pixel unit, and input the output signal processing circuit of each macro-pixel unit; the multiplexer has a close-range and a long-range working mode; in the close-range working mode, the multiplexer uses a time-division multiplexing method to reconstruct the SPAD of the corresponding reconfigurable pixel module and its corresponding front-end circuit to obtain a macro-pixel unit; in the long-range working mode, the multiplexer combines all SPADs in the corresponding reconfigurable pixel module and their corresponding front-end circuits into a macro-pixel unit; The signal processing circuit is used to process and quantize the output of each macro pixel unit to obtain the corresponding distance information quantization result; The working mode / reconstruction control circuit is used to select any one of the close-range working mode and the long-range working mode, and output the corresponding reconstruction and working mode pulse signals; The data processing module is used to rearrange and combine the input distance information quantization results based on the working mode to obtain complete imaging information.

[0030] In a specific embodiment, each reconfigurable pixel module corresponds to a signal processing circuit; and each reconfigurable pixel module is correspondingly connected to at least one multiplexer.

[0031] Example 2 More specifically, in a specific embodiment, the reconfigurable pixel module is composed of 3 x 3 = 9 SPADs and their corresponding front-end circuits.

[0032] In a specific embodiment, Figure 7 , Figure 8 As shown, in the close-range working mode, the macro pixel unit of the multiplexer combination is composed of 2 x 2 = 4 SPADs and their corresponding front-end circuits: in the long-range working mode, the macro pixel unit of the multiplexer combination is composed of 3 x 3 = 9 SPADs and their corresponding front-end circuits.

[0033] In this embodiment, in the close-range working mode, any four adjacent SPADs and their corresponding front-end circuits can be selected for reconstruction to obtain four different reconstruction modes; In a specific embodiment, the signal processing circuit includes a cascaded noise filtering circuit and a time-to-digital converter circuit, which are used to process and quantize the output of the SPAD and its corresponding front-end circuit to obtain the final distance information quantization result; the noise filtering circuit adjusts the noise filtering threshold based on the pulse signal input by the working mode / reconstruction control circuit. The noise filtering threshold of the long-distance working mode is adjusted to be lower than the noise filtering threshold of the short-distance working mode.

[0034] In a specific embodiment, in the close-range working mode, the SPAD of the corresponding reconfigurable pixel module and its corresponding front-end circuit are reconfigured by using a time division multiplexing method, and the specific steps are as follows: Define the time range and divide it into several fixed-length time slots, each of which allows different configurations and working modes to run; In each time slot, different SPADs and corresponding front-end circuits are selected and combined through a multiplexer; In the process of selecting combinations, the complexity and power consumption are reduced by reusing hardware resources in different time slots; All SPADs are combined according to the time slot to obtain a reconstructed macro pixel unit consisting of 2 x 2 = 4 SPADs and their corresponding front-end circuits.

[0035] In a specific embodiment, based on the selection of the working mode, the input distance information quantization results are rearranged and combined, specifically: In the close-range working mode, due to the use of time-division multiplexing reconfigurable mode, based on the predefined mapping relationship, the distance information quantization result data of all macro-pixel units are rearranged according to the order in the complete image, and the data block corresponding to each time slot is placed in the corresponding position of the final image to obtain a frame of complete imaging information; In the long-distance working mode, the detection efficiency of the receiving end is tested. If the detection efficiency of the receiving end is not less than the set condition, all the distance information quantization results are directly arranged in sequence to obtain a frame of complete imaging information; when the detection efficiency of the receiving end is less than the set condition, the distance information quantization results corresponding to each number of adjacent macro-pixel units are merged and then all the distance information quantization results are arranged in sequence to obtain a frame of complete imaging information.

[0036] In a specific embodiment, the distance information quantization results corresponding to each number of adjacent macro-pixel units are merged and then all the merged distance information quantization results are arranged in order to obtain a frame of complete imaging information, specifically: the distance information quantization results corresponding to a single macro-pixel unit and its N adjacent macro-pixel units are processed by weighted filtering to obtain a merged distance information quantization result, where N is an arbitrary positive integer.

[0037] Based on the existing technology, the present invention further proposes a single-photon avalanche diode reconfigurable receiving system and reconstruction method with multiple working modes. The present invention proposes a new reconstruction method including a close-range detection working mode and a long-range detection working mode, which can flexibly increase or decrease the number of SPADs in a single macro-pixel unit, increase the photosensitive area, detection probability, and reduce the loss of effective signals caused by the SPAD being falsely triggered by noise and entering the dead zone. The close-range detection and long-range detection working modes are combined to effectively meet the application requirements in different scenarios.

[0038] Example 3 like Fig. 9 As shown, a reconstruction method of a single-photon avalanche diode reconfigurable receiving system with multiple working modes includes the following specific steps: Based on the distance of the target object to be detected, the working mode / reconfiguration control circuit is set to a short-distance working mode or a long-distance working mode; The working mode / reconstruction control circuit outputs reconstruction and working mode pulse signals to the multiplexer, the signal processing circuit, and the data processing module, and sets the multiplexer, the signal processing circuit, and the data processing module to the corresponding working mode; The multiplexer selects the SPAD of the corresponding reconfigurable pixel module and its corresponding front-end circuit to combine or switch to form a corresponding macro pixel unit based on its working mode; After all macro pixel units receive light signals, they are output to the signal processing circuit through the multiplexer; The distance information quantization result output by the signal processing circuit is input to the data processing module; the data processing module rearranges and combines the input distance information quantization result based on its working mode to obtain complete imaging information.

[0039] Obviously, the above embodiments of the present invention are only examples for clearly explaining the present invention, and are not intended to limit the implementation methods of the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A single-photon avalanche diode reconfigurable receiving system with multiple working modes, characterized in that: Comprising at least one reconfigurable pixel module, at least one multiplexer, at least one signal processing circuit, a working mode / reconstruction control circuit, and a data processing module; The reconfigurable pixel module, the multiplexer, the signal processing circuit, and the data processing module are electrically connected in sequence; the output end of the working mode / reconstruction control circuit is electrically connected to the gating control ends of the multiplexer, the signal processing circuit, and the data processing module; The reconfigurable pixel module is composed of a plurality of single-photon avalanche diodes (SPADs) and their corresponding front-end circuits, and is used to receive reflected light beams; The multiplexer is used to select the SPADs of the corresponding reconfigurable pixel module and their corresponding front-end circuits for combination or switching to form corresponding macro pixel units, and input the output of each macro pixel unit into the signal processing circuit; The signal processing circuit is used to process and quantize the output of each macro pixel unit to obtain a corresponding distance information quantization result; The working mode / reconstruction control circuit is used to select a working mode and output corresponding reconstruction and working mode pulse signals; The data processing module is used to rearrange and combine the input distance information quantization results based on the working mode to obtain complete imaging information.

2. The single-photon avalanche diode reconfigurable receiving system with multiple working modes according to claim 1, characterized in that: The multiplexer has a near-distance and a far-distance working mode; in the near-distance working mode, the multiplexer uses a time-division multiplexing method to reconstruct the SPADs of the corresponding reconfigurable pixel module and their corresponding front-end circuits to obtain a macro pixel unit; in the far-distance working mode, the multiplexer combines all the SPADs and their corresponding front-end circuits in the corresponding reconfigurable pixel module into a macro pixel unit; the working mode / reconstruction control circuit is used to select either the near-distance working mode or the far-distance working mode.

3. The single-photon avalanche diode reconfigurable receiving system with multiple working modes according to claim 1, characterized in that: Specifically, each reconfigurable pixel module corresponds to a signal processing circuit; each reconfigurable pixel module is correspondingly connected to at least one multiplexer.

4. The single-photon avalanche diode reconfigurable receiving system with multiple working modes according to claim 2, characterized in that: The reconfigurable pixel module is composed of K units, each of which consists of m1 × m2 SPADs and the front-end circuit corresponding to each SPAD.

5. The single-photon avalanche diode reconfigurable receiving system with multiple working modes according to claim 4, characterized in that: In the near-distance working mode, the macro pixel unit combined by the multiplexer is composed of n1 x n2 SPADs and their corresponding front-end circuits, where n1 < m1 and n2 < m2; in the far-distance working mode, the macro pixel unit combined by the multiplexer is composed of m1 × m2 SPADs and the corresponding front-end circuits. Where K, m1, m2, n1, and n2 are all positive integers greater than 0.

6. The single-photon avalanche diode reconfigurable receiving system with multiple working modes according to claim 5, characterized in that: The signal processing circuit includes a cascaded noise filtering circuit and a time-to-digital converter circuit, and is used to process and quantize the output of the SPAD and its corresponding front-end circuit to obtain a final distance information quantization result; the noise filtering circuit adjusts the noise filtering threshold based on the pulse signal input by the working mode / reconstruction control circuit.

7. The single-photon avalanche diode reconfigurable receiving system with multiple working modes according to claim 6, characterized in that: In the near-distance working mode, the time-division multiplexing method is used to reconstruct the SPADs of the corresponding reconfigurable pixel module and their corresponding front-end circuits. The specific steps are as follows: Define a time range, divide the time range into several time slots with a fixed length, and each time slot allows different configurations and working modes to run; In each time slot, different SPADs and corresponding front-end circuits are selected and combined through a multiplexer; In the process of selecting combinations, the complexity and power consumption are reduced by reusing hardware resources in different time slots; All SPADs are combined according to the time slot to obtain a macro pixel unit consisting of reconstructed n1 x n2 SPADs and their corresponding front-end circuits.

8. The single-photon avalanche diode reconfigurable receiving system with multiple working modes according to claim 7, characterized in that: Based on the selection of the working mode, the input distance information quantization results are rearranged and combined, specifically: In the close-range working mode, due to the use of time-division multiplexing reconfigurable mode, based on the predefined mapping relationship, the distance information quantization result data of all macro-pixel units are rearranged according to the order in the complete image, and the corresponding data block of each time slot is placed in the corresponding position of the final image to obtain a frame of complete imaging information; In the long-distance working mode, the detection efficiency of the receiving end is tested. If the detection efficiency of the receiving end is not less than the set condition, all the distance information quantization results are directly arranged in order to obtain a complete frame of imaging information; When the detection efficiency of the receiving end is less than the set condition, the distance information quantization results corresponding to each number of adjacent macro-pixel units are merged and all the distance information quantization results are arranged in sequence to obtain a complete frame of imaging information.

9. The single-photon avalanche diode reconfigurable receiving system with multiple working modes according to claim 8, characterized in that: After merging the distance information quantization results corresponding to each number of adjacent macro-pixel units, all the merged distance information quantization results are arranged in order to obtain a frame of complete imaging information. Specifically, the distance information quantization results corresponding to a single macro-pixel unit and its N adjacent macro-pixel units are processed by weighted filtering to obtain a merged distance information quantization result, where N is an arbitrary positive integer.

10. A method for reconfiguring a single-photon avalanche diode reconfigurable receiving system with multiple working modes according to any one of claims 1 to 9, characterized in that: The specific steps include: Based on the distance of the target object to be detected, the working mode / reconfiguration control circuit is set to a short-distance working mode or a long-distance working mode; The working mode / reconstruction control circuit outputs reconstruction and working mode pulse signals to the multiplexer, the signal processing circuit, and the data processing module, and sets the multiplexer, the signal processing circuit, and the data processing module to the corresponding working mode; The multiplexer selects the SPAD of the corresponding reconfigurable pixel module and its corresponding front-end circuit to combine or switch to form a corresponding macro pixel unit based on its working mode; After all macro pixel units receive the light signal, they are output to the signal processing circuit through the multiplexer; The distance information quantization result output by the signal processing circuit is input into the data processing module; The data processing module rearranges and combines the input distance information quantization results based on its working mode to obtain complete imaging information.

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