A DToF ranging method, system and apparatus

Abstract

The application discloses a DToF ranging method, system and device, relates to the technical field of ranging, and obtains a plurality of histograms by changing the time interval between the time when a TDC starts timing and the time when a laser emission end starts emitting laser, obtains a first ranging histogram corresponding to a first frame by combining the histograms, and makes the width of a time bin in the first ranging histogram more fine compared with the width of a time bin of the first histogram, so that the accuracy of determining first depth data based on the first ranging histogram can be improved without changing the TDC resolution.

Description

Technical Field

[0001] This invention relates to the field of ranging technology, and in particular to a DToF ranging method, system and device. Background Technology

[0002] With the continuous advancement of technology, 3D image sensors are increasingly widely used in smartphones and other devices. Direct Time of Flight (DToF) ranging is a ranging technology applied in 3D image sensors. DToF ranging involves emitting short pulses of laser light from a laser emitter and recording the flight time between the emitted laser and the received laser light reflected back from the target object using a Time Digital Converter (TDC). The distance between the laser emitter and the target object is then determined based on this flight time. The accuracy of DToF ranging is closely related to the resolution of the TDC; typically, once the TDC is designed, the measurement accuracy of DToF ranging cannot be further improved, failing to meet the demands of higher-precision devices. Summary of the Invention

[0003] The purpose of this invention is to provide a DToF ranging method, system, and apparatus that can improve the accuracy of determining the first depth data based on the first ranging histogram without changing the TDC resolution.

[0004] To solve the above-mentioned technical problems, the present invention provides a DToF ranging method, comprising:

[0005] In the first frame, the activation time of the control TDC is synchronized with the emission time of the laser emitter, and a first histogram is generated based on the flight time of each laser emitted by the laser emitter measured by the TDC within a single frame detection time.

[0006] In the second frame, the time interval t between the activation time of the TDC and the emission time of the laser emitter is controlled, and a second histogram is generated based on the flight time of each laser emitted by the laser emitter measured by the TDC within the single frame detection time.

[0007] In the i-th frame, the time interval between the turn-on time of the TDC and the emission time of the laser emitter is (i-1)*t. Based on the flight time of each laser emitted by the laser emitter measured by the TDC within the single frame detection time, the i-th histogram is generated, where i is a positive integer not less than 2, t = T / i, and T is the resolution of the TDC.

[0008] The first histogram, the second histogram, and up to the i-th histogram are combined into a first ranging histogram, and the depth data between the laser emitter and the target object in the first frame is determined based on the first ranging histogram.

[0009] Preferably, t = T / 2 M M is a positive number and 1≤M≤10.

[0010] Preferred options also include:

[0011] In the (i+1)th frame, the activation time of the TDC is synchronized with the emission time of the laser emitter, and the (i+1)th histogram is generated based on the flight time of each laser emitted by the laser emitter as measured by the TDC within the single frame detection time.

[0012] Until the (i+i)th frame, the time interval between the turn-on time of the TDC and the emission time of the laser emitter is (i-1)*t. Based on the flight time of each laser emitted by the laser emitter measured by the TDC within the single frame detection time, the 2ith histogram is generated.

[0013] The (i+1)th histogram up to the 2ith histogram are combined into the i-th ranging histogram, and the i-th frame depth data between the laser emitter and the target object at the i-th frame is determined based on the i-th ranging histogram.

[0014] Preferably, controlling the time interval (i-1)*t between the turn-on time of the TDC and the emission time of the laser emitter includes:

[0015] The TDC is turned on first, and after a time interval of (i-1)*t after the TDC is turned on, the laser emitting end is controlled to start emitting laser.

[0016] Preferably, combining the first histogram, the second histogram, up to the i-th histogram, into a first ranging histogram includes:

[0017] The w-th time box in each of the histograms is arranged in descending order of the time interval between the TDC’s activation time and the laser emitter’s emission time to form the w-th ranging time box. The width of each time box included in the ranging time box is reduced to T / i, where w is a positive integer and is between 1 and the total number of time boxes in the first histogram.

[0018] The first ranging histogram is obtained by combining the various ranging time boxes in ascending order of their starting coordinates.

[0019] Preferably, at t = T / 2, it also includes:

[0020] In the 2n-1th frame, the activation time of the TDC is synchronized with the emission time of the laser emitter. Based on the flight time of each laser emitted by the laser emitter measured by the TDC within a single frame detection time, the 2n-1th histogram is generated, where n is a positive integer.

[0021] In the 2nth frame, the time interval t between the turn-on time of the TDC and the emission time of the laser emitter is controlled, and a 2nth histogram is generated based on the flight time of each laser emitted by the laser emitter measured by the TDC within the single frame detection time.

[0022] In the 2n+1st frame, the activation time of the TDC is synchronized with the emission time of the laser emitter, and the 2n+1st histogram is generated based on the flight time of each laser emitted by the laser emitter measured by the TDC within a single frame detection time.

[0023] In the 2n+2nd frame, the time interval t between the turn-on time of the TDC and the emission time of the laser emitter is controlled, and the 2n+2nd histogram is generated based on the flight time of each laser emitted by the laser emitter measured by the TDC within the single frame detection time.

[0024] The (2n-1)th histogram is combined with the 2nth histogram to obtain the (2n-1)th ranging histogram corresponding to the (2n-1)th frame. Based on the (2n-1)th ranging histogram, the depth data of the (2n-1)th frame between the laser emitter and the target object is determined.

[0025] The (2n+1)th histogram is combined with the (2n+2)th histogram to obtain the (2n+1)th ranging histogram corresponding to the (2n+1)th frame. Based on the (2n+1)th ranging histogram, the depth data of the laser emitter and the target object in the (2n+1)th frame is determined.

[0026] Preferably, at t = T / 2, it also includes:

[0027] In the 2n-1th frame, the activation time of the TDC is synchronized with the emission time of the laser emitter. Based on the flight time of each laser emitted by the laser emitter measured by the TDC within a single frame detection time, the 2n-1th histogram is generated, where n is a positive integer.

[0028] In the 2nth frame, the time interval t between the turn-on time of the TDC and the emission time of the laser emitter is controlled, and a 2nth histogram is generated based on the flight time of each laser emitted by the laser emitter measured by the TDC within the single frame detection time.

[0029] In the 2n+1st frame, the activation time of the TDC is synchronized with the emission time of the laser emitter, and the 2n+1st histogram is generated based on the flight time of each laser emitted by the laser emitter measured by the TDC within a single frame detection time.

[0030] In the 2n+2nd frame, the time interval t between the turn-on time of the TDC and the emission time of the laser emitter is controlled, and the 2n+2nd histogram is generated based on the flight time of each laser emitted by the laser emitter measured by the TDC within the single frame detection time.

[0031] The (2n-1)th histogram is combined with the 2nth histogram to obtain the (2n-1)th ranging histogram corresponding to the (2n-1)th frame. Based on the (2n-1)th ranging histogram, the (2n-1)th depth data between the laser emitter and the target object at the (2n-1)th frame is determined.

[0032] The 2nth histogram is combined with the 2n+1th histogram to obtain the 2nth ranging histogram corresponding to the 2nth frame. Based on the 2nth ranging histogram, the 2nth depth data between the laser emitter and the target object at the 2nth frame is determined.

[0033] The (2n+1)th histogram is combined with the (2n+2)th histogram to obtain the (2n+1)th ranging histogram corresponding to the (2n+1)th frame. Based on the (2n+1)th ranging histogram, the (2n+1)th depth data between the laser emitter and the target object at the (2n+1)th frame is determined.

[0034] This application also provides a DToF ranging system, including:

[0035] The first histogram generation unit is used to control the activation time of the TDC to synchronize with the emission time of the laser emitter in the first frame, and generate the first histogram based on the flight time of each laser emitted by the laser emitter measured by the TDC within a single frame detection time.

[0036] The second histogram generation unit is used to control the time interval t between the turn-on time of the TDC and the emission time of the laser emitter in the second frame, and generate a second histogram based on the flight time of each laser emitted by the laser emitter measured by the TDC within the single frame detection time.

[0037] The i-th histogram generation unit is used to control the time interval (i-1)*t between the turn-on time of the TDC and the emission time of the laser emitter in the i-th frame, and generate the i-th histogram based on the flight time of each laser emitted by the laser emitter measured by the TDC within the single frame detection time, where i is a positive integer not less than 2, t = T / i, and T is the resolution of the TDC.

[0038] The first ranging unit is used to combine the first histogram, the second histogram up to the i-th histogram into a first ranging histogram, and determine the first depth data between the laser emitter and the target object in the first frame based on the first ranging histogram.

[0039] This application also provides a DToF ranging device, including:

[0040] Memory, used to store computer programs;

[0041] A processor is used to implement the steps of the DToF ranging method described above when executing the computer program.

[0042] Preferred options also include:

[0043] Laser emitting end, used to emit laser light;

[0044] A laser receiver is used to receive the laser emitted by the laser emitter and reflected back by the target object, and to generate an electrical signal when the laser is received;

[0045] TDC is used to receive the electrical signal generated by the laser receiver and determine the time of flight of the laser, wherein the time of flight is the time required for the laser to travel from the laser emitter to the target object and be reflected back to the laser receiver by the target object.

[0046] In summary, this invention provides a DToF ranging method, system, and apparatus. By changing the time interval between the start time of the TDC and the start time of laser emission from the laser emitter, multiple histograms are obtained. By combining these histograms, a first ranging histogram corresponding to the first frame is obtained. This makes the width of the time box in the first ranging histogram more refined than the width of the time box in the first histogram. Therefore, without changing the TDC resolution, the accuracy of determining the first depth data based on the first ranging histogram can be improved. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the prior art and embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 A schematic flowchart of a DToF ranging method provided by the present invention;

[0049] Figure 2 The first histogram in a DToF ranging method provided in this application;

[0050] Figure 3 The second histogram in a DToF ranging method provided in this application;

[0051] Figure 4 This application provides a first ranging histogram in a DToF ranging method.

[0052] Figure 5 An error waveform diagram of distance measurement based on the first histogram in a DToF distance measurement method provided in this application;

[0053] Figure 6 This application provides an error waveform diagram for distance measurement based on a first distance histogram in a DToF distance measurement method;

[0054] Figure 7 A schematic diagram of a DToF ranging system provided in this application;

[0055] Figure 8 This is a schematic diagram of a DToF ranging device provided in this application. Detailed Implementation

[0056] The core of this invention is to provide a DToF ranging method, system, and device that can improve the accuracy of determining the first depth data based on the first ranging histogram without changing the TDC resolution.

[0057] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0058] Please refer to Figure 1 , Figure 1 This is a flowchart illustrating a DToF ranging method provided by the present invention. The method includes:

[0059] S1: In the first frame, the activation time of the control TDC is synchronized with the emission time of the laser transmitter. The first histogram is generated based on the flight time of each laser emitted by the laser transmitter measured by the TDC within the single frame detection time.

[0060] S2: In the second frame, control the time interval t between the turn-on time of TDC and the emission time of the laser emitter, and generate a second histogram based on the flight time of each laser emitted by the laser emitter measured by TDC within the single frame detection time.

[0061] S3: In the i-th frame, control the time difference between the TDC's activation time and the laser emitter's emission time (i-1)*t. Generate the i-th histogram based on the flight time of each laser emitted by the laser emitter measured by the TDC within a single frame detection time, where i is a positive integer not less than 2, t = T / i, and T is the resolution of the TDC.

[0062] S4: Combine the first histogram, the second histogram up to the i-th histogram into a first ranging histogram, and determine the depth data between the laser emitter and the target object in the first frame based on the first ranging histogram.

[0063] In existing technologies, the accuracy of DToF ranging is limited by the resolution of the Time Control Detector (TDC). Once the TDC design is completed, the accuracy of DToF ranging cannot be further improved. Typically, when performing DToF ranging, it is necessary to synchronize the TDC's activation time with the laser emission time of the laser transmitter. Then, the TDC determines the flight time (the time it takes for the laser to travel from the laser transmitter, through the target object, and then to the laser receiver) of each laser emitted by the laser transmitter within a single frame detection time. Based on the flight time of each laser within a single frame detection time, a histogram is generated for that frame. The horizontal axis of the histogram represents the flight time, the vertical axis represents the number of received photons, and the width of the time bin in the histogram represents the resolution of the TDC.

[0064] It should also be noted that, in the art, the process of TDC determining the flight time of each laser and generating a histogram based on the flight time of each laser in a single frame detection time is generally referred to as a frame. The generation process of the histogram in each frame is the same. Therefore, in this application, the first frame is used as an example for explanation. The process of generating the ranging histogram and performing ranging based on the ranging histogram in subsequent frames can repeat the steps of the first frame.

[0065] Without changing the resolution of the TDC itself, this application obtains a new first ranging histogram by combining various histograms. The time box width of the first ranging histogram is more refined than that of each individual histogram, and the number of lasers corresponding to the first ranging histogram is greater than that of each individual histogram within the same flight time range. Therefore, the accuracy of the first depth data determined based on the first ranging histogram is higher.

[0066] Specifically, in this application, to obtain a more refined first ranging histogram, it is necessary to first obtain i histograms with different delay times, where i is a predetermined value. Once i is determined, the step size of the time interval change between the TDC's activation time and the laser emitter's emission time is also determined. The step size t is specifically T / i, where T is the resolution of the TDC, i.e., the width of the time bin in the initial first histogram, the second histogram, and the i-th histogram. It is easy to understand that, theoretically, the larger the value of i, the more histograms are combined to form the first ranging histogram, and the more refined the width of the time bin in the first ranging histogram, thus resulting in higher ranging accuracy. In practical applications, the value of i can be adjusted according to the required ranging accuracy.

[0067] In a preferred embodiment, when the time interval between the TDC activation time and the laser emitter's emission time in the i-th frame is (i-1)*t, the TDC can be activated first, and then the laser emitter can be activated after a time interval of (i-1)*t. That is, no intervention is needed in the TDC's operation; the TDC still cycles on and off according to the single-frame detection time. Since the laser emitter is controlled externally to the chip, while the TDC is controlled internally, controlling the laser emitter's activation is easier. Therefore, the method described in this application—activating the TDC first and then activating it after a certain time interval—is easier to operate and reduces the complexity of DToF ranging.

[0068] Specifically, in the first frame, the activation time of the TDC (Transmission Control Center) is synchronized with the emission time of the laser transmitter. Then, the TDC determines the flight time of each laser within the single-frame detection time and generates a first histogram based on the flight time of each laser. From the second frame to the i-th frame, the time interval between the activation time of the TDC and the emission time of the laser transmitter increases by T / i sequentially. The process of generating histograms from the second frame to the i-th frame is the same as that of the first frame, and will not be elaborated upon here. Finally, the first histogram from the first frame to the i-th histogram from the i-th frame are combined to generate the first ranging histogram corresponding to the first frame.

[0069] As a preferred embodiment, the process of combining the first histogram up to the i-th histogram into the first ranging histogram can be specifically as follows: The w-th timeboxes of each histogram are combined to obtain the w-th ranging timebox in the first ranging histogram. Furthermore, the w-th timeboxes in each histogram need to be arranged in descending order of the time interval between the TDC's activation time and the laser emitter's emission time to ensure the accuracy of the first ranging histogram. Finally, the ranging timeboxes are arranged in ascending order of their starting coordinates to obtain the first ranging histogram.

[0070] It should also be noted that during the combination of timeboxes, the width of each timebox is reduced to T / i. This means that the ranging timebox in the first ranging histogram can be considered as consisting of i timeboxes, and therefore the width of the ranging timebox in the first ranging histogram can be considered as T / i. The method for ranging using the first ranging histogram is typically as follows: the flight time with the most lasers in the first ranging histogram is determined as the ranging flight time, and half of the product of the preset flight speed and the ranging flight time is taken as the ranging result. Therefore, in this application, because the width of the ranging timebox in the first ranging histogram is more refined, the determined ranging flight time is more accurate, ultimately achieving the goal of improving ranging accuracy without changing the TDC resolution.

[0071] For example, t = T / 2, please refer to... Figure 2 , Figure 3 and Figure 4 , Figure 2 This is the first histogram in a DToF ranging method provided in this application. Figure 3 This application provides a second histogram for a DToF ranging method. Figure 4 The first ranging histogram in the DToF ranging method provided in this application shows that the accuracy of the ranging timebox in the first ranging histogram is 0.5, while the accuracy of the timeboxes in the first and second histograms is 1, indicating that the first ranging histogram has higher accuracy.

[0072] In summary, this invention provides a DToF ranging method that obtains multiple histograms by changing the time interval between the start time of the TDC and the start time of laser emission from the laser emitter. By combining these histograms, a first ranging histogram corresponding to the first frame is obtained. This makes the width of the time box in the first ranging histogram more refined than the width of the time box in the first histogram. Therefore, without changing the TDC resolution, the accuracy of determining the first depth data based on the first ranging histogram can be improved.

[0073] Based on the above embodiments:

[0074] As a preferred embodiment, t = T / 2 M M is a positive number and 1≤M≤10.

[0075] In this embodiment, the step size t of the time interval between the TDC's activation time and the laser emitter's emission time is specifically T / 2. M Furthermore, M is between 1 and 10. When M = 1, the equivalent resolution of the TDC is reduced by half; when M = 10, the equivalent resolution of the TDC is reduced to half of its original value. 10If the resolution continues to decrease, the system will need to perform too many scans, resulting in excessive computation of the synthesized data. This will reduce ranging efficiency and increase system storage resources. Please refer to... Figure 5 and Figure 6 , Figure 5 This application provides an error waveform diagram for distance measurement based on the first histogram in a DToF distance measurement method. Figure 6 This application provides an error waveform diagram for distance measurement based on a first distance histogram in a DToF distance measurement method. Figure 6 The corresponding first ranging histogram is composed of the first histogram and the second histogram. When the second histogram is generated, the time interval t between the TDC and the emission time of the laser emitter is t = T / 2. It can be seen that using the first ranging histogram for ranging can reduce the error from ±210mm to ±55mm.

[0076] As a preferred embodiment, it also includes:

[0077] In the (i+1)th frame, the activation time of the control TDC is synchronized with the emission time of the laser transmitter, and the (i+1)th histogram is generated based on the flight time of each laser emitted by the laser transmitter measured by the TDC within a single frame detection time.

[0078] Until the (i+i)th frame, the time interval between the turn-on time of the control TDC and the emission time of the laser emitter is (i-1)*t. Based on the flight time of each laser emitted by the laser emitter measured by the TDC within the single frame detection time, the 2ith histogram is generated.

[0079] The (i+1)th histogram and so on up to the 2ith histogram are combined into the i-th ranging histogram, and the i-th frame depth data between the laser emitter and the target object is determined based on the i-th ranging histogram.

[0080] In this application, when the time interval between the TDC's activation time and the laser emission time of the laser transmitter is t = T / i, each i histograms can be combined to form a new frame of ranging histograms. Therefore, this embodiment provides a general method for generating the ranging histograms of each frame. Specifically, similar to the process of generating the first ranging histogram corresponding to the first frame, it is necessary to first control the TDC and the laser transmitter to start synchronously in frame i+1, and generate the i+1th histogram based on the flight time of each laser emitted by the laser transmitter measured by the TDC within the single frame detection time. i is incremented by one each time, and the time interval between the TDC's activation time and the laser emission time of the laser transmitter is also increased by T / i in turn, until the second i histogram corresponding to the second i frame is obtained according to the above process.

[0081] Then, the (i+1)th histogram and so on up to the 2ith histogram are combined into the i-th ranging histogram corresponding to the i-th frame. The process of combining the individual histograms into the i-th ranging histogram is not detailed here; it can be referred to the process of combining the first to the i-th histogram when generating the first ranging histogram. Similarly, the timebox precision in the combined i-th ranging histogram is higher than that in the (i+1)th histogram and so on up to the 2ith histogram, making the time of flight determined during ranging in the i-th frame more accurate. Therefore, the value of the i-th frame depth data between the laser emitter and the target object determined based on the time of flight is also more accurate.

[0082] As a preferred embodiment, at t = T / 2, it further includes:

[0083] In the 2n-1 frame, the activation time of the control TDC is synchronized with the emission time of the laser transmitter. Based on the flight time of each laser emitted by the laser transmitter measured by the TDC within a single frame detection time, the 2n-1 histogram is generated, where n is a positive integer.

[0084] In the 2nth frame, the time interval t between the turn-on time of the control TDC and the emission time of the laser emitter is used to generate the 2nth histogram based on the flight time of each laser emitted by the laser emitter measured by the TDC within the single frame detection time.

[0085] In the 2n+1 frame, the activation time of the control TDC is synchronized with the emission time of the laser transmitter, and the 2n+1 histogram is generated based on the flight time of each laser emitted by the laser transmitter measured by the TDC within the single frame detection time.

[0086] In the 2n+2nd frame, the time interval t between the turn-on time of the control TDC and the emission time of the laser emitter is used to generate the 2n+2nd histogram based on the flight time of each laser emitted by the laser emitter measured by the TDC within the single frame detection time.

[0087] The 2n-1 histogram is combined with the 2n histogram to obtain the 2n-1 ranging histogram corresponding to the 2n-1 frame. Based on the 2n-1 ranging histogram, the depth data of the laser emitter and the target object in the 2n-1 frame is determined.

[0088] The (2n+1)th histogram is combined with the (2n+2)th histogram to obtain the (2n+1)th ranging histogram corresponding to the (2n+1)th frame. Based on the (2n+1)th ranging histogram, the depth data between the laser emitter and the target object in the (2n+1)th frame is determined.

[0089] In this embodiment, the time interval between the TDC activation time and the laser emission time of the laser transmitter is fixed at T / 2. When t = T / 2, the accuracy of the depth data when ranging is based on the ranging histograms corresponding to each frame can be significantly improved. Furthermore, only two histograms are needed to form a new ranging histogram, reducing the amount of data processing and improving the efficiency of ranging.

[0090] When t = T / 2, in this embodiment, the histograms corresponding to two adjacent frames are combined into a new ranging histogram. The histograms used by each ranging histogram are not repeated. Therefore, in the process of combining the ranging histograms, it is not necessary to adjust the time boxes in the histograms according to the order of the delay time from long to short. This makes the process of generating the ranging histogram simpler and speeds up the ranging efficiency.

[0091] Specifically, firstly, histograms corresponding to each frame are generated. This embodiment will not elaborate on the generation process of the histograms for each frame. After obtaining the histograms for each frame, the (2n-1)th histogram is combined with the 2nth histogram to obtain the (2n-1)th ranging histogram corresponding to the (2n-1)th frame. The (2n+1)th histogram is combined with the (2n+2)th histogram to obtain the (2n+1)th ranging histogram corresponding to the (2n+1)th frame. Then, the depth data corresponding to the (2n-1)th frame and the depth data corresponding to the (2n+1)th frame are obtained based on the (2n-1)th and (2n+1)th ranging histograms, respectively. Since the width of the ranging timebox in each ranging histogram in this embodiment is half the width of the original histogram's timebox, the final flight time determined based on the ranging histogram is more accurate, thus ensuring that the ranging accuracy in this application is more accurate than that of the prior art.

[0092] As a preferred embodiment, at t = T / 2, it further includes:

[0093] In the 2n-1 frame, the activation time of the control TDC is synchronized with the emission time of the laser transmitter. Based on the flight time of each laser emitted by the laser transmitter measured by the TDC within a single frame detection time, the 2n-1 histogram is generated, where n is a positive integer.

[0094] In the 2nth frame, the time interval t between the turn-on time of the control TDC and the emission time of the laser emitter is used to generate the 2nth histogram based on the flight time of each laser emitted by the laser emitter measured by the TDC within the single frame detection time.

[0095] In the 2n+1 frame, the activation time of the control TDC is synchronized with the emission time of the laser transmitter, and the 2n+1 histogram is generated based on the flight time of each laser emitted by the laser transmitter measured by the TDC within the single frame detection time.

[0096] In the 2n+2nd frame, the time interval t between the turn-on time of the control TDC and the emission time of the laser emitter is used to generate the 2n+2nd histogram based on the flight time of each laser emitted by the laser emitter measured by the TDC within the single frame detection time.

[0097] The 2n-1 histogram is combined with the 2n histogram to obtain the 2n-1 ranging histogram corresponding to the 2n-1 frame. Based on the 2n-1 ranging histogram, the 2n-1 depth data between the laser emitter and the target object at the 2n-1 frame is determined.

[0098] The 2nth histogram is combined with the 2n+1th histogram to obtain the 2nth ranging histogram corresponding to the 2nth frame. Based on the 2nth ranging histogram, the 2nth depth data between the laser emitter and the target object at the 2nth frame is determined.

[0099] The (2n+1)th histogram is combined with the (2n+2)th histogram to obtain the (2n+1)th ranging histogram corresponding to the (2n+1)th frame. Based on the (2n+1)th ranging histogram, the (2n+1)th depth data between the laser emitter and the target object at the (2n+1)th frame is determined.

[0100] In this embodiment, the time interval between the TDC activation time and the laser emission time of the laser transmitter is fixed at T / 2. When t = T / 2, the accuracy of the depth data when ranging is based on the ranging histograms corresponding to each frame can be significantly improved. Furthermore, only two histograms are needed to form a new ranging histogram, reducing the amount of data processing and improving the efficiency of ranging.

[0101] Furthermore, this embodiment also considers that combining the histograms of two non-overlapping adjacent frames into a new ranging histogram will result in a loss of frame rate. Specifically, as can be seen from the previous embodiment, when the total number of histograms is 2n+2, the total number of ranging histograms obtained is n+1, resulting in only n+1 depth data points. Therefore, in this embodiment, combining the histograms of any two adjacent frames into a new ranging histogram results in a total number of ranging histograms of 2n+2, with the frame rate loss being almost negligible.

[0102] Specifically, firstly, histograms corresponding to each frame are generated. This embodiment will not elaborate on the generation process of the histograms for each frame. After obtaining the histograms for each frame, the (2n-1)th histogram is combined with the 2nth histogram to obtain the (2n-1)th ranging histogram corresponding to the 2n-1th frame. The 2nth histogram is combined with the 2n+1th histogram to obtain the 2nth ranging histogram corresponding to the 2nth frame. Then, the depth data corresponding to the (2n-1)th frame, the depth data corresponding to the 2nth frame, and the depth data corresponding to the 2n+1th frame are obtained based on the (2n-1)th ranging histogram, the 2nth ranging histogram, and the 2n+1 ranging histogram, respectively. It can be seen that when the total number of histograms is 2n+2, the final total number of ranging histograms is 2n+1.

[0103] For example, in frame 3, the TDC activation time and laser emission time are synchronized to obtain the third histogram; in frame 4, the TDC activation time and laser emission time are delayed by a time interval t to obtain the fourth histogram; in frame 5, the TDC activation time and laser emission time are synchronized again to obtain the fifth histogram. Then, the third and fourth histograms are combined to obtain a new third histogram; the fifth and fourth histograms are combined to obtain a new fourth histogram. The depth data for frame 3 is calculated using the new third histogram; the depth data for frame 4 is calculated using the new fourth histogram. It can be seen that the total number of histograms is 5, and the total number of ranging histograms is 4, with only the data from the last frame being lost, thus having a limited impact on the ranging results.

[0104] In summary, when prioritizing the simplicity and speed of generating the ranging histogram, the combination method of the previous embodiment can be used. When prioritizing minimizing the loss of histogram data in each frame, the combination method provided in this embodiment should be preferred.

[0105] Please refer to Figure 7 , Figure 7 A schematic diagram of a DToF ranging system provided in this application is shown. The system includes:

[0106] The first histogram generation unit 11 is used to control the turn-on time of TDC to synchronize with the emission time of the laser emitter in the first frame, and generate the first histogram based on the flight time of each laser emitted by the laser emitter measured by TDC within the single frame detection time.

[0107] The second histogram generation unit 12 is used in the second frame to control the time interval t between the turn-on time of TDC and the emission time of the laser emitter, and to generate a second histogram based on the flight time of each laser emitted by the laser emitter measured by TDC within the single frame detection time.

[0108] The i-th histogram generation unit 13 is used to control the time interval (i-1)*t between the turn-on time of TDC and the emission time of the laser emitter in the i-th frame, and generate the i-th histogram based on the flight time of each laser emitted by the laser emitter measured by TDC in a single frame detection time, where i is a positive integer not less than 2, t = T / i, and T is the resolution of TDC.

[0109] The first ranging unit 14 is used to combine the first histogram, the second histogram up to the i-th histogram into a first ranging histogram, and determine the first depth data between the laser emitter and the target object in the first frame based on the first ranging histogram.

[0110] For a detailed description of the DToF ranging system provided in this application, please refer to the embodiments of the DToF ranging method described above; further details will not be repeated here.

[0111] Based on the above embodiments:

[0112] As a preferred embodiment, t = T / 2 M M is a positive number and 1≤M≤10.

[0113] As a preferred embodiment, it also includes:

[0114] The (i+1)th histogram generation unit is used to control the activation time of the TDC to synchronize with the emission time of the laser transmitter in the (i+1)th frame, and generate the (i+1)th histogram based on the flight time of each laser emitted by the laser transmitter measured by the TDC within a single frame detection time.

[0115] The second i-th histogram generation unit is used to control the time interval (i-1)*t between the turn-on time of the TDC and the emission time of the laser emitter until the (i+i)th frame, and generate the second i-th histogram based on the flight time of each laser emitted by the laser emitter measured by the TDC within the single frame detection time.

[0116] The i-th frame ranging unit is used to combine the (i+1)-th histogram up to the 2i-th histogram into the i-th ranging histogram, and determine the i-th frame depth data between the laser emitter and the target object based on the i-th ranging histogram.

[0117] As a preferred embodiment, controlling the time interval (i-1)*t between the turn-on time of the TDC and the emission time of the laser emitter includes:

[0118] The TDC is turned on first, and after a time interval of (i-1)*t, the laser emitter is controlled to start emitting laser.

[0119] As a preferred embodiment, the first histogram, the second histogram, and so on up to the i-th histogram are combined to form a first ranging histogram, including:

[0120] The w-th time box in each histogram is arranged in descending order of the time interval between the TDC’s activation time and the laser transmitter’s emission time to form the w-th ranging time box. The width of each time box included in the ranging time box is reduced to T / i, where w is a positive integer and is between 1 and the total number of time boxes in the first histogram.

[0121] The first ranging histogram is obtained by combining the various ranging time boxes in ascending order of their starting coordinates.

[0122] As a preferred embodiment, at t = T / 2, it further includes:

[0123] The (2n-1)th histogram generation unit is used in the (2n-1)th frame to control the activation time of the TDC to synchronize with the emission time of the laser transmitter. It generates the (2n-1)th histogram based on the flight time of each laser emitted by the laser transmitter measured by the TDC within a single frame detection time, where n is a positive integer.

[0124] The 2n-th histogram generation unit is used to control the time interval t between the turn-on time of the TDC and the emission time of the laser emitter in the 2n-th frame, and generate the 2n-th histogram based on the flight time of each laser emitted by the laser emitter measured by the TDC within the single frame detection time.

[0125] The 2n+1 histogram generation unit is used to control the TDC activation time to synchronize with the laser emitter's emission time in the 2n+1 frame, and generate the 2n+1 histogram based on the flight time of each laser emitted by the laser emitter measured by the TDC within a single frame detection time.

[0126] The 2n+2 histogram generation unit is used in the 2n+2 frame to control the time interval t between the turn-on time of TDC and the emission time of the laser emitter, and to generate the 2n+2 histogram based on the flight time of each laser emitted by the laser emitter measured by TDC within a single frame detection time.

[0127] The 2n-1 frame ranging unit is used to combine the 2n-1 histogram with the 2n histogram to obtain the 2n-1 frame ranging histogram corresponding to the 2n-1 frame, and to determine the depth data of the 2n-1 frame between the laser emitter and the target object based on the 2n-1 frame ranging histogram.

[0128] The 2n+1 frame ranging unit is used to combine the 2n+1 histogram with the 2n+2 histogram to obtain the 2n+1 ranging histogram corresponding to the 2n+1 frame, and to determine the depth data of the laser emitter and the target object in the 2n+1 frame based on the 2n+1 ranging histogram.

[0129] As a preferred embodiment, at t = T / 2, it further includes:

[0130] The (2n-1)th histogram generation unit is used in the (2n-1)th frame to control the activation time of the TDC to synchronize with the emission time of the laser transmitter. It generates the (2n-1)th histogram based on the flight time of each laser emitted by the laser transmitter measured by the TDC within a single frame detection time, where n is a positive integer.

[0131] The 2n-th histogram generation unit is used to control the time interval t between the turn-on time of the TDC and the emission time of the laser emitter in the 2n-th frame, and generate the 2n-th histogram based on the flight time of each laser emitted by the laser emitter measured by the TDC within the single frame detection time.

[0132] The 2n+1 histogram generation unit is used to control the TDC activation time to synchronize with the laser emitter's emission time in the 2n+1 frame, and generate the 2n+1 histogram based on the flight time of each laser emitted by the laser emitter measured by the TDC within a single frame detection time.

[0133] The 2n+2 histogram generation unit is used in the 2n+2 frame to control the time interval t between the turn-on time of TDC and the emission time of the laser emitter, and to generate the 2n+2 histogram based on the flight time of each laser emitted by the laser emitter measured by TDC within a single frame detection time.

[0134] The 2n-1 depth data determination unit is used to combine the 2n-1 histogram with the 2n histogram to obtain the 2n-1 ranging histogram corresponding to the 2n-1 frame, and determine the 2n-1 depth data between the laser emitter and the target object in the 2n-1 frame based on the 2n-1 ranging histogram.

[0135] The 2n depth data determination unit is used to combine the 2n histogram with the 2n+1 histogram to obtain the 2n ranging histogram corresponding to the 2n frame, and determine the 2n depth data between the laser emitter and the target object at the 2n frame based on the 2n ranging histogram.

[0136] The 2n+1 depth data determination unit is used to combine the 2n+1 histogram with the 2n+2 histogram to obtain the 2n+1 ranging histogram corresponding to the 2n+1 frame, and determine the 2n+1 depth data between the laser emitter and the target object at the 2n+1 frame based on the 2n+1 ranging histogram.

[0137] Please refer to Figure 8 , Figure 8 This application provides a schematic diagram of a DToF ranging device, which includes:

[0138] Memory 21 is used to store computer programs;

[0139] The processor 22 is used to implement the steps of the DToF ranging method described above when executing a computer program.

[0140] For a detailed description of the DToF ranging device provided in this application, please refer to the embodiments of the DToF ranging method described above; further details will not be repeated here.

[0141] Based on the above embodiments:

[0142] As a preferred embodiment, it also includes:

[0143] Laser emitting end, used to emit laser light;

[0144] The laser receiver is used to receive the laser emitted by the laser transmitter and reflected back by the target object, and to generate an electrical signal when the laser is received.

[0145] TDC is used to receive the electrical signal generated by the laser receiver and determine the time of flight of the laser, where the time of flight is the time required for the laser to travel from the laser emitter to the target object and be reflected back to the laser receiver by the target object.

[0146] In this embodiment, the DToF ranging device further includes a laser transmitter, a laser receiver, and a time-distribution converter (TDC). The processor in the DToF ranging device controls the activation time of the TDC and the emission time of the laser transmitter. After the TDC is activated, it cyclically detects the flight time of each laser emitted by the laser transmitter within a single frame detection time. In this embodiment, since the laser receiver can receive the laser reflected back from the target object and generate an electrical signal after receiving the reflected laser, the TDC can achieve the purpose of determining the flight time. Finally, the processor generates a histogram corresponding to each frame based on the flight time of each laser measured by the TDC within a single frame detection time, and combines the histograms into a ranging histogram, thereby achieving the purpose of more accurately determining the depth data between the laser transmitter and the target object based on the ranging histogram.

[0147] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0148] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0149] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A DToF ranging method, characterized in that, include: In the first frame, the activation time of the control TDC is synchronized with the emission time of the laser emitter, and a first histogram is generated based on the flight time of each laser emitted by the laser emitter measured by the TDC within a single frame detection time. In the second frame, the time interval t between the activation time of the TDC and the emission time of the laser emitter is controlled, and a second histogram is generated based on the flight time of each laser emitted by the laser emitter measured by the TDC within the single frame detection time. In the i-th frame, the time interval between the turn-on time of the TDC and the emission time of the laser emitter is (i-1)*t. Based on the flight time of each laser emitted by the laser emitter measured by the TDC within the single frame detection time, the i-th histogram is generated, where i is a positive integer not less than 2, t=T / i, and T is the resolution of the TDC. The first histogram, the second histogram, and up to the i-th histogram are combined into a first ranging histogram, and the depth data between the laser emitter and the target object in the first frame is determined based on the first ranging histogram.

2. The DToF ranging method of claim 1, wherein, t = T / 2 M , M is a positive number and ; i = 2 M .

3. The DToF ranging method of claim 1, wherein, Also includes: In the (i+1)th frame, the activation time of the TDC is synchronized with the emission time of the laser emitter, and the (i+1)th histogram is generated based on the flight time of each laser emitted by the laser emitter as measured by the TDC within the single frame detection time. Until the (i+i)th frame, the time interval between the turn-on time of the TDC and the emission time of the laser emitter is (i-1)*t. Based on the flight time of each laser emitted by the laser emitter measured by the TDC within the single frame detection time, the 2ith histogram is generated. The (i+1)th histogram up to the 2ith histogram are combined into the i-th ranging histogram, and the i-th frame depth data between the laser emitter and the target object at the i-th frame is determined based on the i-th ranging histogram.

4. The DToF ranging method of claim 1, wherein, Controlling the time interval (i-1)*t between the turn-on time of the TDC and the emission time of the laser emitter includes: The TDC is turned on first, and after a time interval of (i-1)*t after the TDC is turned on, the laser emitting end is controlled to start emitting laser.

5. The DToF ranging method as described in claim 1, characterized in that, Combining the first histogram, the second histogram, up to the i-th histogram, into a first ranging histogram includes: The w-th time box in each of the histograms is arranged in descending order of the time interval between the TDC’s activation time and the laser emitter’s emission time to form the w-th ranging time box. The width of each time box included in the ranging time box is reduced to T / i, where w is a positive integer and is between 1 and the total number of time boxes in the first histogram. The first ranging histogram is obtained by combining the various ranging time boxes in ascending order of their starting coordinates.

6. The DToF ranging method as described in claim 1, characterized in that, At t=T / 2, it also includes: In the 2n-1th frame, the activation time of the TDC is synchronized with the emission time of the laser emitter. Based on the flight time of each laser emitted by the laser emitter measured by the TDC within a single frame detection time, the 2n-1th histogram is generated, where n is a positive integer. In the 2nth frame, the time interval t between the turn-on time of the TDC and the emission time of the laser emitter is controlled, and a 2nth histogram is generated based on the flight time of each laser emitted by the laser emitter measured by the TDC within the single frame detection time. In the 2n+1st frame, the activation time of the TDC is synchronized with the emission time of the laser emitter, and the 2n+1st histogram is generated based on the flight time of each laser emitted by the laser emitter measured by the TDC within a single frame detection time. In the 2n+2nd frame, the time interval t between the turn-on time of the TDC and the emission time of the laser emitter is controlled, and the 2n+2nd histogram is generated based on the flight time of each laser emitted by the laser emitter measured by the TDC within the single frame detection time. The (2n-1)th histogram is combined with the 2nth histogram to obtain the (2n-1)th ranging histogram corresponding to the (2n-1)th frame. Based on the (2n-1)th ranging histogram, the depth data of the (2n-1)th frame between the laser emitter and the target object is determined. The (2n+1)th histogram is combined with the (2n+2)th histogram to obtain the (2n+1)th ranging histogram corresponding to the (2n+1)th frame. Based on the (2n+1)th ranging histogram, the depth data of the laser emitter and the target object in the (2n+1)th frame is determined.

7. The DToF ranging method of claim 1, wherein, At t=T / 2, it also includes: In the 2n-1th frame, the activation time of the TDC is synchronized with the emission time of the laser emitter. Based on the flight time of each laser emitted by the laser emitter measured by the TDC within a single frame detection time, the 2n-1th histogram is generated, where n is a positive integer. In the 2nth frame, the time interval t between the turn-on time of the TDC and the emission time of the laser emitter is controlled, and a 2nth histogram is generated based on the flight time of each laser emitted by the laser emitter measured by the TDC within the single frame detection time. In the 2n+1st frame, the activation time of the TDC is synchronized with the emission time of the laser emitter, and the 2n+1st histogram is generated based on the flight time of each laser emitted by the laser emitter measured by the TDC within a single frame detection time. In the 2n+2nd frame, the time interval t between the turn-on time of the TDC and the emission time of the laser emitter is controlled, and the 2n+2nd histogram is generated based on the flight time of each laser emitted by the laser emitter measured by the TDC within the single frame detection time. The (2n-1)th histogram is combined with the 2nth histogram to obtain the (2n-1)th ranging histogram corresponding to the (2n-1)th frame. Based on the (2n-1)th ranging histogram, the (2n-1)th depth data between the laser emitter and the target object at the (2n-1)th frame is determined. The 2nth histogram is combined with the 2n+1th histogram to obtain the 2nth ranging histogram corresponding to the 2nth frame. Based on the 2nth ranging histogram, the 2nth depth data between the laser emitter and the target object at the 2nth frame is determined. The (2n+1)th histogram is combined with the (2n+2)th histogram to obtain the (2n+1)th ranging histogram corresponding to the (2n+1)th frame. Based on the (2n+1)th ranging histogram, the (2n+1)th depth data between the laser emitter and the target object at the (2n+1)th frame is determined.

8. A DToF ranging system, characterized in that, include: The first histogram generation unit is used to control the activation time of the TDC to synchronize with the emission time of the laser emitter in the first frame, and generate the first histogram based on the flight time of each laser emitted by the laser emitter measured by the TDC within a single frame detection time. The second histogram generation unit is used to control the time interval t between the turn-on time of the TDC and the emission time of the laser emitter in the second frame, and generate a second histogram based on the flight time of each laser emitted by the laser emitter measured by the TDC within the single frame detection time. The i-th histogram generation unit is used to control the time interval (i-1)*t between the turn-on time of the TDC and the emission time of the laser emitter in the i-th frame, and generate the i-th histogram based on the flight time of each laser emitted by the laser emitter measured by the TDC in the single frame detection time, where i is a positive integer not less than 2, t=T / i, and T is the resolution of the TDC. The first ranging unit is used to combine the first histogram, the second histogram up to the i-th histogram into a first ranging histogram, and determine the first depth data between the laser emitter and the target object in the first frame based on the first ranging histogram.

9. A DToF ranging device, characterized in that, include: Memory, used to store computer programs; A processor, configured to implement the steps of the DToF ranging method as described in any one of claims 1 to 7 when executing the computer program.

10. The DToF ranging device of claim 9, wherein, Also includes: Laser emitting end, used to emit laser light; A laser receiver is used to receive the laser emitted by the laser emitter and reflected back by the target object, and to generate an electrical signal when the laser is received; TDC is used to receive the electrical signal generated by the laser receiver and determine the time of flight of the laser, wherein the time of flight is the time required for the laser to travel from the laser emitter to the target object and be reflected back to the laser receiver by the target object.

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