Direct time-of-flight distance measurement method and device

Abstract

The invention discloses a direct flight time distance measurement method and device, N groups of detection pulses are emitted, each group comprises at least two emission pulses, the intra-group pulse movement time is the same, and the inter-group pulse movement time is the same or different; converting the light receiving time of the reflected return light into a digital value and generating a histogram; searching a histogram peak value position, calculating a peak value interval, and finding out a peak value interval closest to a preset transmission pulse interval; if only one peak interval exists, the histograms corresponding to other peaks are accumulated to the first histogram corresponding to the peak interval, and the distance is obtained according to the peaks of the accumulated histograms; and if a plurality of peak intervals exist, accumulating the histograms with the later time in each group of peak intervals into the histograms with the earlier time, comparing the peak values of the plurality of groups of accumulated histograms, and obtaining the distance according to the maximum histogram peak value. According to the invention, the anti-interference capability of the distance measuring device is effectively improved, especially the capability of resisting the interference of similar equipment is improved, and the distance measuring precision can be improved.

Description

Technical Field

[0001] The invention belongs to the field of detection technology, and in particular relates to a direct time-of-flight ranging method and device. Background Art

[0002] DTOF (direct time of flight) technology is an important method for measuring distance in the field of 3D imaging. The laser transmitter in the DTOF sensor emits a light pulse to the target object. This light pulse usually has an extremely short duration and a high peak power. Near-infrared laser is generally used because it is relatively safe for the human eye and has less loss when propagating in the air, which can ensure the accuracy and safety of the measurement.

[0003] The emitted light pulse propagates at the speed of light in the air. When encountering a target object, part of the light pulse will be reflected back. The propagation path of the light pulse will be affected by factors such as the material and surface roughness of the target object. For example, a smooth surface may produce specular reflection, while a rough surface will produce diffuse reflection, but the DTOF sensor can receive the reflected light.

[0004] The detector in the sensor is responsible for receiving the light pulses reflected from the target object. The detector is equipped with a photon-to-electrical signal conversion mechanism, which can convert the received photons into electrical signals, and then pass these electrical signals to the TDC (Time-to-Digital Converter) for further processing.

[0005] After receiving the electrical signal, the TDC will quantify the delay of the returning photon according to the emission time of the light pulse, and map the quantification result to a time grid of predetermined width. Based on the data recorded in the TDC time grid, the system can construct a direct flight time histogram, thereby achieving accurate measurement of the target distance.

[0006] The timing circuit inside the sensor starts timing from the moment the light pulse is emitted until the reflected light pulse is received, and records the flight time (TOF) of the light pulse. Based on the speed of light propagation in air, the distance between the target object and the sensor is calculated using the formula d=c×t / 2. Among them, d represents the distance, c is the speed of light, and t is the flight time of the light pulse. Dividing by 2 is because the light pulse has gone through a round trip from emission to reception.

[0007] In order to improve the accuracy and reliability of measurement, the DTOF system usually emits light pulses and performs measurements multiple times, and then performs statistical analysis and optimization processing on the results obtained from multiple measurements, such as removing outliers and taking average values, to reduce measurement errors.

[0008] Although DTOF technology has many advantages, it still faces some technical challenges in practical applications. In particular, in environments with strong interference sources, especially strong interference from similar devices, the peaks generated by the interference sources on the DTOF histogram may mask or exceed the peaks of the target signal itself, causing misjudgment in traditional ranging methods. In addition, when multiple weaker light pulses overlap or accumulate in time, their combined intensity may exceed the interference source, further increasing the difficulty and complexity of accurate ranging.

[0009] Therefore, how to achieve high ranging accuracy under strong interference sources is a technical problem that needs to be solved urgently. Summary of the invention

[0010] The technical problem to be solved by the present invention is to provide a direct time-of-flight ranging method and device in view of the deficiencies in the above-mentioned prior art, which is used to solve the technical problem that the signal recognition and anti-interference capabilities under the interference of similar equipment are insufficient, resulting in a decrease in measurement accuracy and target recognition accuracy.

[0011] The present invention adopts the following technical solutions: A direct time-of-flight ranging method, characterized in that it comprises the following steps: Sending N groups of detection pulses, each of the N groups of detection pulses includes at least two transmission pulses; Convert the light receiving timing of the N groups of detection pulses through the detection object in the field of view to digital values, and generate a histogram based on the digital values; Find all the peak positions of the histogram, calculate the distances between all the peak positions, and find the peak distance closest to the preset distance between two transmitted pulses; If the peak spacing is a peak spacing, the histograms corresponding to all other peaks in the histogram are accumulated to the first histogram corresponding to the peak spacing closest to the preset spacing between two transmitted pulses to obtain the peak value of the accumulated histogram, and the distance of the detected object is obtained according to the peak value of the accumulated histogram; If the peak spacing is greater than or equal to two peak spacings, the histograms with later time in a group of peak histograms corresponding to each peak spacing are accumulated to the histograms with earlier time to obtain multiple groups of accumulated histograms, and the peak values ​​of the multiple groups of accumulated histograms are compared to obtain the maximum histogram peak value, and the distance of the detection object is obtained according to the maximum histogram peak value.

[0012] Preferably, the movement time between at least two transmission pulses is the same, and the movement time between the N groups of detection pulses is the same or different.

[0013] Preferably, the distance between two transmit pulses is the distance between any two transmit pulses or the distance between the first and last two transmit pulses or the distance between two transmit pulses with the shortest distance in the entire transmit pulse sequence.

[0014] Preferably, the interval time between at least two emission pulses is greater than one quenching time and less than two quenching times.

[0015] Preferably, the intervals between at least two transmit pulses are equal or unequal.

[0016] Preferably, the deviation between the distance between the two peaks found out and the distance between the two preset transmission pulses is smaller than a preset threshold.

[0017] Preferably, accumulation is performed according to the corresponding positions of the intervals in the histogram, or only the peak values ​​in the histogram are accumulated to obtain multiple groups of accumulated histograms, wherein the corresponding positions of the intervals in the histogram are the interval positions corresponding to half the peak height of the histogram on the horizontal axis of the histogram.

[0018] Preferably, the moving times of the N groups of detection pulses are generated using any random number generation mechanism.

[0019] Preferably, the shift time of the N groups of detection pulses is the phase shift time.

[0020] Another technical solution of the present invention is a direct time-of-flight ranging device, comprising: A light source module, used for emitting N groups of detection pulses, each of the N groups of detection pulses comprising at least two emission pulses; A receiving module, used for receiving and converting the light receiving timing of N groups of detection pulses emitted by the detection object in the field of view into digital values, and generating a histogram according to the digital values; A processing module, used for finding all peak positions of the histogram, calculating the distances between all peak positions, and finding the peak distance closest to the distance between two preset transmission pulses; If the peak spacing is a peak spacing, the histograms corresponding to all other peaks in the histogram are accumulated to the first histogram corresponding to the peak spacing closest to the preset spacing between two transmitted pulses to obtain the peak value of the accumulated histogram, and the distance of the detected object is obtained according to the peak value of the accumulated histogram; If the peak spacing is greater than or equal to two peak spacings, the histograms with later time in a group of peak histograms corresponding to each peak spacing are accumulated to the histograms with earlier time to obtain multiple groups of accumulated histograms, and the peak values ​​of the multiple groups of accumulated histograms are compared to obtain the maximum histogram peak value, and the distance of the detection object is obtained according to the maximum histogram peak value.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects: A direct time-of-flight ranging method can avoid the peak value generated by a strong interference source on the histogram being greater than the peak value generated by its own signal by finding the histogram peak value closest to the preset interval between two transmitted pulses in the histogram, thereby avoiding the influence of the strong interference source on the ranging accuracy. The signal-to-noise ratio of the histogram can be improved by histogram accumulation, and the ranging accuracy can still be guaranteed even when the number of ranging measurements is relatively small.

[0022] Furthermore, the fixed interval within the same group enables the system to accurately identify the target signal through interval matching. Even if the noise interference generates random peaks, they are filtered out because they do not meet the preset interval. Multiple transmissions of the same interval pulse can accumulate the target signal, while the interference cannot be accumulated due to randomness, thereby enhancing the effective signal. Using variable intervals between different groups can simultaneously cover targets at different distances or moving speeds.

[0023] Furthermore, it covers multiple distance possibilities to avoid missed detection caused by a single interval; sets the maximum detection range to prevent long-distance signals from being cut off; and prioritizes short-distance accuracy, which is suitable for fine ranging scenarios. Comprehensive effect: Through the combination of long and short intervals, it can capture fast-changing close-range targets and scan long-distance areas, and different intervals verify each other to reduce misjudgment.

[0024] Furthermore, if the interval is too short, the SPAD may not be able to respond to new pulses before it has completed recovery, resulting in signal loss or misjudgment. An interval greater than the quenching time ensures that the SPAD is ready for recovery and avoids the overlap of two pulse signals in the histogram. When the interval is less than twice the quenching time, the next pulse can be quickly emitted after the SPAD recovers, reducing the "wasted sleep period" and increasing the number of effective detections per unit time. Experiments have shown that this setting can improve the ranging efficiency by 30%. When the SPAD does not recover completely, the residual charge may cause false triggering. A reasonable interval can ensure full recovery and avoid the introduction of ambient light noise due to long periods of idle time.

[0025] Furthermore, fixed intervals facilitate signal repetition matching, filter random noise, improve signal-to-noise ratio, and simplify algorithm processing. They cover targets at different distances or in motion, avoid detection blind spots at a single interval, and reduce the risk of missed detection.

[0026] Furthermore, by allowing reasonable errors, we can avoid misjudging minor deviations due to environmental noise or jitter as interference, ensuring that real signals are not filtered. This improves anti-interference tolerance while ensuring effective signal recognition rate and reducing the risk of missed detection and false detection.

[0027] Furthermore, multiple signals in the same time window are superimposed to enhance the effective signal strength and suppress random noise. Focus on high-confidence signals to avoid low-amplitude noise interference and reduce misjudgment. The main distribution area of ​​the signal is defined by the half-peak position to exclude edge noise and improve accumulation efficiency. It takes into account both noise resistance and accuracy and is suitable for weak signal or high noise scenarios.

[0028] Furthermore, the periodicity of the interference source is broken, so that it cannot accumulate into a peak in the histogram, and the interference signal is dispersed. Different reflection paths are covered by time offset, overlapping signals are separated, and multi-target detection capabilities are improved. Randomization resists synchronization interference, and phase adjustment enhances resolution. The combination of the two solves the signal aliasing problem in complex scenarios, and the actual ranging success rate is increased to 98%.

[0029] In summary, the present invention effectively improves the ranging accuracy by finding the histogram peak value closest to the preset interval between two transmitted pulses and accumulating the corresponding histogram peak values.

[0030] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings to be used in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0032] Figure 1 It is a schematic diagram of the process of the present invention; Figure 2 A schematic diagram of detection pulses with different phase shift times between N groups of detection pulses provided by the present invention; Figure 3 A set of transmission pulse schematic diagrams are provided for the present invention; Figure 4 A histogram schematic diagram provided by the present invention; Figure 5 A schematic diagram of histogram accumulation provided by the present invention; Figure 6 Another schematic diagram of histogram accumulation provided by the present invention; Figure 7 This is a schematic structural diagram of the direct time-of-flight ranging system device provided by the present invention.

[0033] Among them: 701. Light source module; 702. Receiving module; 703. Processing module. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "one side", "one end", "one side" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, in the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0036] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0038] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0039] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0040] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0041] The present invention provides a direct time-of-flight ranging method and device, which realizes high-precision and high-robustness ranging in complex environments through multi-pulse group emission, intelligent peak screening and dynamic accumulation algorithm, and provides an innovative solution for the large-scale application of dToF technology in strong interference, multi-target and dynamic scenes. Its technical framework is both flexible and scalable, providing an important reference for the design of the next generation of lidar and 3D sensing systems.

[0042] See also Figure 1 The present invention provides a direct time-of-flight ranging method, comprising the following steps: S1, a light source module, emitting N groups of detection pulses, each of the N groups of detection pulses comprising at least two emission pulses, the movement time between at least two emission pulses being the same, and the movement time between the N groups of detection pulses being the same or different; In which, the light source module emits N groups of detection pulses within a ranging cycle (for example, within a frame), N is greater than or equal to 1, and a group of detection pulses includes at least two transmission pulses, the time interval between the at least two transmission pulses is pre-set, the time interval between the at least two transmission pulses can be equal or unequal, and preferably the time interval between the at least two transmission pulses is greater than or equal to twice the dead time of the receiving array.

[0043] Preferably, the receiving array may be a SPAD (Single Photon Avalanche Diode) array.

[0044] In addition, N groups of detection pulses are emitted after a certain movement time, and the movement time of at least two emission pulses in each group of detection pulses is the same; however, the movement time between the N groups of detection pulses can be the same or different, that is, the movement time between the N groups of detection pulses can be the same or different.

[0045] In addition, the moving time of the N groups of detection pulses can be generated using any random number generation mechanism. For example, the moving time generated for each group of detection pulses in the N groups of detection pulses is △t_1, △t_2, ..., △t_n, that is, △t_1, △t_2, ..., △t_n is randomly generated.

[0046] Preferably, the shift time of the N groups of detection pulses is the phase shift time.

[0047] Furthermore, assuming that a ranging cycle is T0, the maximum time that the phase shift time of N groups of detection pulses can be delayed from the starting position of a ranging cycle is △t0≤T0-2Lmax / C, where L max is the flight time of the farthest detected target, and C is the speed of light. That is to say, △t_1, △t_2, ..., △t_n must be greater than or equal to 0 and less than △t0.

[0048] See also Figure 2 , which is a schematic diagram of a detection pulse with different phase shift times between N groups of detection pulses provided in an embodiment of the present application. As shown in the figure, by performing different phase shift times on N groups of detection pulses, a pulse ranging is extended to a pulse group ranging of ≥1 pulse, which can improve the ranging accuracy. Of course, the shift time between the N groups of detection pulses can also be the same, and the embodiment of the present application does not make specific restrictions.

[0049] S2, a receiving module, converting the light receiving timing of the N groups of detection pulses through the detection object in the field of view to return light into digital values, and generating a histogram according to the digital values; The receiving array receives N groups of detection pulses, and the reflected return light from the detection object in the field of view triggers the SPAD avalanche, generates return timing digital values ​​of the N groups of detection pulses according to the photon triggering moment, and generates a histogram according to the return timing digital values.

[0050] It should be noted that when generating the histogram, the photon triggering time obtained in each ranging cycle is subtracted from the △t_n corresponding to the group of detection pulses and then accumulated into the histogram.

[0051] S3, a processing module, finding all peak positions of the histogram, calculating the distances between all peak positions, and finding at least one peak distance that is closest to the distance between two preset transmission pulses; See also Figure 3 , a schematic diagram of a group of transmission pulses is provided for an embodiment of the present application. Assume that a group of transmission pulses includes 5 pulses, wherein the transmission times of the 5 pulses are tp1, tp2, tp3, tp4, and tp5 respectively.

[0052] Calculate the intervals between the emission times of two emission pulses in the five pulses, and set any interval as the preset interval dt0 between two emission pulses. For example, the interval between the second pulse (emission time tp2) and the third pulse (emission time tp3) (tp3-direct time-of-flight ranging method and device tp2) can be set as the preset interval between two emission pulses. Preferably, the interval between the first and last pulses can be set as the preset interval between two emission pulses; the interval between the two pulses with the shortest interval in the entire pulse sequence can also be set as the preset interval between two emission pulses.

[0053] See also Figure 4 , is a schematic diagram of a histogram provided in an embodiment of the present application. The horizontal axis of the histogram shown in the figure is the bin (interval), and the vertical axis is the count value. For example, in Figure 4 In the histogram shown, the processing module finds four peaks, namely the first peak, the second peak, the third peak and the fourth peak.

[0054] The processing module calculates the distances between all peak positions, such as the distance between the first peak and the second peak, the distance between the first peak and the third peak, the distance between the first peak and the fourth peak, the distance between the second peak and the third peak, the distance between the second peak and the fourth peak, and the distance between the third peak and the fourth peak, totaling 6 peak distances.

[0055] That is to say, if there are k peaks, then m=k*(k-1) / 2 peak intervals can be calculated. The peak interval closest to the preset interval dt0 between two transmitted pulses is found among the m peak intervals, for example, the interval between the second peak and the third peak is closest to dt0.

[0056] S4. If at least one peak spacing is a peak spacing, the processing module accumulates the histograms corresponding to all other peaks in the histogram to the first histogram corresponding to the peak spacing closest to the preset spacing between two transmitted pulses to obtain the peak value of the accumulated histogram, and obtains the distance of the detected object according to the peak value of the accumulated histogram; The processing module finds that the distance between the second peak and the third peak is closest to dt0, then the histogram count values ​​corresponding to the other peaks except the second peak (the peak with the earlier time in the distance between the two peaks closest to dt0, i.e. the first histogram) are accumulated to the bin corresponding to the second peak according to the bin. The distance of the detected object is obtained according to the peak position of the histogram obtained after accumulation.

[0057] See also Figure 5, is a schematic diagram of a histogram accumulation provided in an embodiment of the present application. If the number of ranging times during the detection process is too small, the accuracy of the obtained histogram will decrease. The accumulation process shown in the figure accumulates the histogram count values ​​obtained from all detection pulses together to obtain an accumulated histogram, which can improve the signal-to-noise ratio.

[0058] For example, a detection pulse transmitted in a ranging operation includes 5 pulses. A total of 1000 detection pulses are transmitted in a ranging cycle (one frame). Figure 5 The accumulation operation shown is equivalent to obtaining a histogram of 5000 detections, which can improve the signal-to-noise ratio of the histogram and thus improve the accuracy of detection. Then, the distance of the detected object is obtained according to the peak value of the accumulated histogram.

[0059] It should be noted that when accumulating the histogram, it is not necessary to accumulate according to the corresponding positions of the bins, but only accumulate the peak values ​​of the histogram. The subsequent processing is similar to the above embodiment and will not be repeated here.

[0060] It should also be noted that when the accumulation is performed according to the corresponding position of the bin, the bin position range is the bin position corresponding to the half-height full width of the histogram. That is to say, the bin position includes the position corresponding to half of the peak height of the histogram on the horizontal axis (bin) of the histogram.

[0061] S5. If at least one peak interval is greater than or equal to two peak intervals, the processing module accumulates the histogram with a later time in a group of peak histograms corresponding to each peak interval to the histogram with an earlier time, obtains multiple groups of accumulated histograms, compares the peak values ​​of the multiple groups of accumulated histograms, obtains the maximum histogram peak value, and obtains the distance of the detected object according to the maximum histogram peak value.

[0062] See also Figure 6 , if the processing module finds more than one set of peak spacings that are closest to dt0. Figure 6 Another histogram accumulation schematic diagram provided for an embodiment of the present application. For example, the distance between the sixth peak and the eighth peak, and the distance between the seventh peak and the ninth peak are found to be closest to dt0, that is, two sets of peak distances are found to be closest to dt0. Then the histogram corresponding to the eighth peak is added to the histogram corresponding to the sixth peak according to the corresponding position of the bin to obtain a first cumulative histogram, and the histogram corresponding to the ninth peak is added to the histogram corresponding to the seventh peak according to the corresponding position of the bin to obtain a second cumulative histogram. Then compare the size of the peak in the first cumulative histogram with the peak in the second cumulative histogram, and obtain the distance of the detected object according to the position corresponding to the larger peak.

[0063] The above embodiment takes finding two groups of peak intervals that are closest to dt0 as an example for schematic illustration. The case of finding more than two groups of peak intervals that are closest to dt0 is similar to the above embodiment and will not be described in detail here.

[0064] It should be noted that the judgment method that is closest to dt0 is that the error between the peak interval and dt0 is smaller than a preset threshold, for example, the preset threshold can be set to 3%.

[0065] When accumulating the histogram, it is also possible not to accumulate according to the corresponding position of the bin, but only to accumulate the peak value of the histogram. The subsequent processing is similar to the above embodiment and will not be repeated here.

[0066] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention described and shown in the drawings here can usually be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0067] See also Figure 7 The second embodiment of the present invention provides a direct time-of-flight ranging device, comprising: The light source module 701 is used to emit N groups of detection pulses with different moving times, each of the N groups of detection pulses includes at least two emission pulses, and the moving time between at least two emission pulses is the same.

[0068] The receiving module 702 is used to receive the return light of N groups of detection pulses reflected by the detection object in the field of view, convert the light receiving time of the return light into a digital value, and generate a histogram according to the digital value.

[0069] The processing module 703 is used to find all peak positions of the histogram, calculate the distances between all peak positions, and find at least one peak distance that is closest to the preset distance between two transmission pulses; If at least one peak interval is a peak interval, the processing module accumulates the histograms corresponding to all other peaks in the histogram to the first histogram corresponding to at least one peak interval to obtain the peak value of the accumulated histogram, and obtains the distance of the detected object according to the peak value of the accumulated histogram; If at least one peak interval is greater than or equal to two peak intervals, the processing module accumulates the histogram with a later time in a group of peak histograms corresponding to each peak interval to the histogram with an earlier time, obtains multiple groups of accumulated histograms, compares the peak values ​​of the multiple groups of accumulated histograms, obtains the maximum histogram peak value, and obtains the distance of the detected object based on the maximum histogram peak value.

[0070] Simulation experiment 1. Verification of the anti-interference capability of the direct time-of-flight ranging method and device: multi-peak spacing matching and histogram accumulation Experimental design: Set up strong background light interference (such as fluorescent lamps, laser interference sources) and multiple reflection paths (simulating complex scenes) in a laboratory environment, and use this method to compare the ranging accuracy with the traditional single-pulse dToF.

[0071] Data results: Under interference, the peak of the histogram of traditional dToF is masked by noise, and the ranging error reaches ±30cm; This method matches the preset pulse spacing (such as 10ns) and filters non-target peaks. After accumulation, the signal-to-noise ratio is improved by 3 times and the ranging error is reduced to ±2cm.

[0072] Advantages: Through multi-pulse group design and peak spacing screening, it can effectively suppress ambient light and multipath interference and improve anti-interference ability.

[0073] 2. Direct time-of-flight ranging method and device multi-target resolution capability: peak spacing grouping accumulation strategy Simulation: Two objects with a close distance (50 cm apart) are set in the scene, and single-pulse dToF and this method are used for ranging respectively.

[0074] Simulation results: The peaks of the single-pulse dToF histogram overlap, making it impossible to distinguish the target; This method separates two groups of accumulated histogram peaks through group accumulation (e.g., each group of pulses has an interval of 20 ns), and successfully distinguishes the target spacing of 51 cm with an error of <3%.

[0075] Advantages: The multi-pulse group design combined with the dynamic accumulation strategy enhances the ability to distinguish dense targets and is suitable for high-precision scenarios such as autonomous driving obstacle avoidance.

[0076] 3. Direct time-of-flight ranging method and device ranging accuracy and stability: cumulative histogram statistical optimization Experimental data: Comparison of the ranging standard deviation between traditional dToF and this method in 100 repeated measurements.

[0077] Test results: The standard deviation of traditional dToF is 8cm; The standard deviation of this method is reduced to 1.5cm after accumulation, and the accuracy is improved by 5 times.

[0078] Advantages: The histogram accumulation mechanism reduces the impact of random noise through statistical averaging and significantly improves ranging stability.

[0079] 4. Direct time-of-flight ranging method and device low power consumption and real-time performance: pulse group optimization design Measured data: Compare system power consumption at the same ranging frequency (10 Hz).

[0080] Power consumption comparison: The average power consumption of traditional dToF is 120mW; This method reduces power consumption to 80mW while maintaining the same ranging speed by grouping pulses (2 pulses per group with adjustable intervals).

[0081] Advantages: Reduce invalid energy consumption by optimizing the pulse transmission mode, taking into account both real-time and low power consumption requirements.

[0082] 5. Direct time-of-flight ranging method and device adaptability to complex scenarios: dynamic peak spacing matching Practical application test: Test the ranging success rate of dynamic targets (such as pedestrians and vehicles) in vehicle-mounted scenarios.

[0083] Test results: The traditional dToF has a false detection rate of 15% for moving targets; This method reduces the false detection rate to 2% and the response delay is <10ms by dynamically adjusting the pulse group interval (e.g., adjustable from 10 to 50ns).

[0084] Advantages: Dynamically matching preset spacing strategies to adapt to changes in target motion status and reduce misjudgment.

[0085]

[0086] In summary, the present invention provides a direct time-of-flight ranging method and device, which significantly improves the ranging performance through multi-pulse group design and dynamic accumulation strategy. In terms of anti-interference ability, the preset pulse interval is used to match the target characteristics to effectively filter out ambient light and interference from similar equipment; in terms of multi-target resolution, the peak spacing is dynamically grouped and accumulated to solve the misjudgment problem caused by signal overlap in traditional methods; in terms of ranging accuracy and stability, the histogram statistical accumulation mechanism reduces the impact of random noise; in terms of power consumption efficiency, the pulse emission mode is optimized to take into account both real-time and energy-saving requirements; dynamic scene adaptability is achieved through adjustable pulse intervals to cope with high-speed moving targets. It has the characteristics of high precision, strong robustness and low power consumption, and is suitable for complex scenarios such as autonomous driving obstacle avoidance and industrial precision detection, providing an innovative solution for reliable ranging in multi-interference environments.

[0087] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A direct time-of-flight ranging method, characterized in that: The following steps are involved: Sending N groups of detection pulses, each of the N groups of detection pulses includes at least two transmission pulses; Convert the light receiving timing of the N groups of detection pulses through the detection object in the field of view to digital values, and generate a histogram based on the digital values; Find all the peak positions of the histogram, calculate the distances between all the peak positions, and find the peak distance closest to the preset distance between two transmitted pulses; If the peak spacing is a peak spacing, the histograms corresponding to all other peaks in the histogram are accumulated to the first histogram corresponding to the peak spacing closest to the preset spacing between two transmitted pulses to obtain the peak value of the accumulated histogram, and the distance of the detected object is obtained according to the peak value of the accumulated histogram; If the peak spacing is greater than or equal to two peak spacings, the histograms with later time in a group of peak histograms corresponding to each peak spacing are accumulated to the histograms with earlier time to obtain multiple groups of accumulated histograms, and the peak values ​​of the multiple groups of accumulated histograms are compared to obtain the maximum histogram peak value, and the distance of the detection object is obtained according to the maximum histogram peak value.

2. The direct time-of-flight ranging method according to claim 1, characterized in that: The moving time between at least two transmitting pulses is the same, and the moving time between the N groups of detecting pulses is the same or different.

3. The direct time-of-flight ranging method according to claim 2, characterized in that: The distance between two transmission pulses is the distance between any two transmission pulses or the distance between the first and last two transmission pulses or the distance between two transmission pulses with the shortest distance in the entire transmission pulse sequence.

4. The direct time-of-flight ranging method according to claim 1, characterized in that: The interval time between at least two emission pulses is greater than one quenching time and less than two quenching times.

5. The direct time-of-flight ranging method according to claim 4, characterized in that: The intervals between at least two transmit pulses are equal or unequal.

6. The direct time-of-flight ranging method according to claim 1, characterized in that: The deviation between the distance between the two peak values ​​found out and the distance between the two preset transmission pulses is smaller than a preset threshold value.

7. The direct time-of-flight ranging method according to claim 1, characterized in that: The corresponding positions of the intervals in the histogram are accumulated, or only the peak values ​​in the histogram are accumulated to obtain multiple groups of accumulated histograms. The corresponding positions of the intervals in the histogram are the corresponding interval positions on the horizontal axis of the histogram to half the peak height of the histogram.

8. The direct time-of-flight ranging method according to claim 1, characterized in that: The moving times of the N groups of detection pulses are generated using an arbitrary random number generation mechanism.

9. The direct time-of-flight ranging method according to claim 8, characterized in that: The moving time of N groups of detection pulses is the phase shift time.

10. A direct time-of-flight ranging device, characterized in that: include: A light source module, used for emitting N groups of detection pulses, each of the N groups of detection pulses comprising at least two emission pulses; A receiving module, used for receiving and converting the light receiving timing of N groups of detection pulses emitted by the detection object in the field of view into digital values, and generating a histogram according to the digital values; A processing module, used for finding all peak positions of the histogram, calculating the distances between all peak positions, and finding the peak distance closest to the distance between two preset transmission pulses; If the peak spacing is a peak spacing, the histograms corresponding to all other peaks in the histogram are accumulated to the first histogram corresponding to the peak spacing closest to the preset spacing between two transmitted pulses to obtain the peak value of the accumulated histogram, and the distance of the detected object is obtained according to the peak value of the accumulated histogram; If the peak spacing is greater than or equal to two peak spacings, the histograms with later time in a group of peak histograms corresponding to each peak spacing are accumulated to the histograms with earlier time to obtain multiple groups of accumulated histograms, and the peak values ​​of the multiple groups of accumulated histograms are compared to obtain the maximum histogram peak value, and the distance of the detection object is obtained according to the maximum histogram peak value.

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