Ranging method and system for a single-line MEMS lidar

Abstract

The present invention relates to the technical field of measuring instruments, and particularly relates to a ranging method and system for a single-line MEMS lidar. It solves the problem of false detection in the existing single-line MEMS lidar under the conditions of interference echoes and multiple echoes. The ranging system includes a laser emission unit, a micro-mirror unit, a laser reception unit, and a main control unit; in the ranging method, the single echo measurement data of several vibration periods at the same vibration angle of the MEMS mirror is filtered, such as median filtering, median value filtering, or forming a histogram of the flight time, and the peak time of the histogram is used as the final measurement time, and then the measurement distance is calculated. The anti-interference ability and multi-echo detection ability of the single-line MEMS lidar are improved, the false detection rate is greatly reduced, and thus the ranging performance of the single-line MEMS lidar is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of measuring instruments, and particularly to a ranging method and system for a single-line MEMS lidar. Background Art

[0002] Compared with traditional mechanical lidars, MEMS (Micro-Electro-Mechanical System) lidars have the advantages of small size, simple structure, easy mass production, low cost, high reliability, etc., and are an important development trend of lidars.

[0003] A single-line MEMS lidar is a 2-D lidar based on a MEMS micromirror. Since the MEMS micromirror is in a high-speed resonant state and its vibration frequency can be as high as several thousand hertz, the ranging method of the MEMS lidar is limited to a single echo measurement method.

[0004] The MEMS lidar based on the single echo measurement method has false detection situations under conditions such as emission spot truncation, multi-lidar interference, rainy and foggy weather, etc., which may generate interference echoes or multiple echoes. Summary of the Invention

[0005] The purpose of the present invention is to provide a ranging method and system for a single-line MEMS lidar aiming at the measurement problems of existing single-line MEMS lidars under interference echoes and multiple echo conditions.

[0006] The technical solution of the present invention is to provide a ranging method for a single-line MEMS lidar, which is characterized by including the following steps:

[0007] Step 1: Control the micromirror to perform simple harmonic vibration according to a set amplitude A / 2 and a set frequency F; where A is the overall scanning angle of the lidar.

[0008] Step 2: According to the lidar range and micromirror parameters, calculate the number of scanning cycles N required for the lidar to scan all N preset scanning angles in one frame, T and N T a preset scanning angle sequence table composed of N scanning cycles, and store it; where the number of scanning cycles N T ≥1, and the time of N T scanning cycles is the time for the lidar to scan one frame, denoted as the frame period.

[0009] Step 3: Capture the angle feedback electrical signal generated during the vibration of the micromirror, and combine it with the preset scanning angle sequence table. When the micromirror moves to the Y-th preset scanning angle in the preset scanning angle sequence table in the X-th frame period, output an X_Y electrical pulse signal to drive the light source to generate a pulsed light beam. After being collimated, the pulsed light beam is emitted towards the preset scanning angle Y direction of the measured area through the micromirror.

[0010] Step 4: Receive and store the first i time-of-flight data at the preset scanning angle Y, where i is an integer greater than or equal to 1.

[0011] Step 5: Repeat Steps 3 and 4 until M frame periods are stored, where each frame period contains the time-of-flight data at N preset scanning angles; where X ≤ M and Y ≤ N.

[0012] Step 6: Sequentially read all the time-of-flight data at the preset scanning angle Y within M frame periods; filter the i*M time-of-flight data at this preset scanning angle and use it as the final measured time-of-flight at this preset scanning angle.

[0013] Step 7: Repeat Step 6 until the processing of the time-of-flight data at all N preset scanning angles for one frame of lidar scanning is completed.

[0014] Step 8: Convert the final time-of-flight at the preset scanning angles output in the above steps into distance information and transmit it to the host device, with an upload frame rate of

[0015] Further, the filtering process in Step 6 is specifically as follows:

[0016] Perform mean filtering or median filtering on the i*M time-of-flight data at this preset scanning angle and use it as the final measured time-of-flight at this preset scanning angle.

[0017] Or,

[0018] Divide the i*M time-of-flight data at this preset scanning angle into several intervals according to the upper and lower extreme values and a fixed time interval, thereby forming a histogram of the time-of-flight at this preset scanning angle, and use the peak time position of this histogram as the final measured time-of-flight at this preset scanning angle.

[0019] Further, the preset scanning angle sequence list in Step 2 needs to satisfy: During the vibration of the micromirror, the time interval T i , A i+1 between any two adjacent preset scanning angles A in the preset scanning angle sequence list is greater than the maximum echo flight time T i ; where max ; where, D is the lidar range and c is the speed of light.

[0020] Further, the above N preset scanning angles are evenly distributed at equal angular intervals or discretely distributed at non-equal angular intervals.

[0021] Further, Step 2 is specifically as follows:

[0022] Step 2.1: Calculate the first adjacent two angles A among the N preset scanning anglesi , A i+1 During the time interval T of the first scanning period i ; N preset scanning angles are sorted in advance according to the angles scanned successively within one scanning period of the galvanometer;

[0023] Step 2.2. Compare T i with T max , where If T i > T max , then sort A i , A i+1 in sequence and put them into the preset scanning angle sequence list of the first scanning period; otherwise, go to Step 2.3;

[0024] Step 2.3. Retain A i and continue as the calculation of the preset scanning angle sequence list of the first scanning period. Exclude A i+1 from the N preset scanning angles and retain it for the calculation of the preset scanning angle sequence list of the second scanning period;

[0025] Step 2.4. Calculate the time interval T i between the two adjacent angles in the preset scanning angles retained in the preset scanning angle sequence list of the first scanning period i+2 , A i+3 …; Repeat the operations in Steps 2.2 to 2.3 until the preset scanning angle sequence list of the first scanning period is completed; i ; Repeat the operations in Steps 2.2 to 2.3 until the preset scanning angle sequence list of the first scanning period is completed;

[0026] Step 2.5. Calculate the time interval T i between the two adjacent angles in the preset scanning angles calculated in the preset scanning angle sequence list retained in the second scanning period;

[0027] Repeat the operations in Steps 2.2 to 2.4 until the preset scanning angle sequence list of the second scanning period is completed; The preset scanning angles calculated in the preset scanning angle sequence list retained in the second scanning period are also sorted according to the angles scanned successively within one scanning period of the galvanometer; i ; Repeat the operations in Steps 2.2 to 2.4 until the preset scanning angle sequence list of the corresponding scanning period is completed, until all the preset scanning angles are covered.

[0028] Further, in step 1, a control circuit is used to generate a periodic driving electrical signal to the micromirror driving circuit to control the micromirror to perform simple harmonic vibration with a set amplitude A / 2 and a set frequency F.

[0029] Further, in step 3, the logic processing circuit captures the angle feedback electrical signal generated by the micromirror during vibration; the light source driving circuit captures the above X_Y electrical pulse signal to drive the light source to generate a pulsed laser beam, and the pulsed laser beam forms a collimated beam through the light receiving and transmitting optical path and is emitted through the micromirror in the preset angle Y direction of the measured area.

[0030] Further, in step 4, the control circuit receives the first i flight time data of the preset scanning angle Y and stores them in the storage unit with the address X*Y in the storage circuit;

[0031] The first i flight time data of the preset scanning angle Y are obtained through the following process:

[0032] A plurality of optical pulse echo signals returned in the preset angle Y direction of the measured area are converged to the optical receiving element through the micromirror and the light receiving and transmitting optical path or separately through the light receiving and transmitting optical path. The optical receiving element generates a photocurrent, and the flight time reading circuit amplifies and converts the above photocurrent into a plurality of flight time data of the preset angle Y.

[0033] Further, in step 6, the control circuit sequentially reads all the flight time data of the preset scanning angle Y stored within M frame periods.

[0034] The present invention also provides a ranging method for a single-line MEMS lidar, which is characterized in that it includes the following steps:

[0035] Step 1, controlling the micromirror to perform simple harmonic vibration with a set amplitude A / 2 and a set frequency F; where A is the overall scanning angle of the lidar;

[0036] Step 2, according to the lidar range and micromirror parameters, calculate the number of scanning cycles N required for the lidar to scan all N preset scanning angles in one frame T and N T a preset scanning angle sequence table composed of N scanning cycles, and store it; where the number of scanning cycles N T ≥1, the time of N T scanning cycles is the time for the lidar to scan one frame, denoted as the frame period;

[0037] Step 3, capturing the angle feedback electrical signal generated by the micromirror during vibration, combining with the preset scanning angle sequence table, and outputting an X_Y electrical pulse signal when the micromirror moves to the Yth preset scanning angle in the preset scanning angle sequence table in the Xth frame period, driving the light source to generate a pulsed beam, and the pulsed beam is collimated and then emitted through the micromirror in the preset scanning angle Y direction of the measured area;

[0038] Step 4: Receive and store the first i time-of-flight data at the preset scanning angle Y; where i is an integer greater than or equal to 1;

[0039] Step 5: Repeat Steps 3 and 4 until M1 frame periods are stored, with N1 time-of-flight data at preset scanning angles of interest in each frame period;

[0040] Or, repeat Steps 3 and 4 until M2 frame periods are stored, with N2 time-of-flight data at preset scanning angles of non-interest in each frame period;

[0041] Where N1 + N2 = N, N is the number of preset scanning angles, and M1 < M2;

[0042] Step 6: Sequentially read all the time-of-flight data at the preset scanning angle of interest Y1 within i * M1 frame periods; filter the i * M1 time-of-flight data at this preset scanning angle of interest and use it as the final measured time-of-flight at this preset scanning angle;

[0043] Or, sequentially read all the time-of-flight data at the preset scanning angle of non-interest Y2 within i * M2 frame periods; filter the i * M2 time-of-flight data at this preset scanning angle of non-interest and use it as the final measured time-of-flight at this preset scanning angle;

[0044] Step 7: Repeat Step 6 until the processing of the time-of-flight data at all N1 preset scanning angles of interest or all N2 preset scanning angles of non-interest is completed;

[0045] Step 8: Convert the final time-of-flight at a frame of preset scanning angle of interest or non-interest output in the above steps into distance information and transmit it to the host device. The upload frame rate for the preset scanning angle of interest is The upload frame rate for the preset scanning angle of non-interest is

[0046] Further, the filtering process in Step 6 is specifically as follows:

[0047] Perform mean filtering or median filtering on the i * M1 or i * M2 time-of-flight data at this preset scanning angle and use it as the final measured time-of-flight at this preset scanning angle;

[0048] Or,

[0049] Divide the i * M1 or i * M2 time-of-flight data at this preset scanning angle into several intervals according to the upper and lower extreme values and a fixed time interval, thereby forming a histogram of the time-of-flight at this preset scanning angle, and use the peak time position of this histogram as the final measured time-of-flight at this preset scanning angle.

[0050] Further, the preset scanning angle sequence table in step 2 should satisfy that during the vibration of the micromirror, the time interval T between any two adjacent preset scanning angles A i , A i+1 in the preset scanning angle sequence table is greater than the maximum echo flight time T i ; where max ; where D is the range of the lidar and c is the speed of light. D is the range of the lidar and c is the speed of light.

[0051] Further, the above N preset scanning angles are evenly distributed at equal angular intervals or discretely distributed at non-equal angular intervals; the N1 preset scanning angles of interest and the N2 preset scanning angles of non-interest are respectively continuous angular intervals or discrete angular combinations.

[0052] Further, step 2 is specifically as follows:

[0053] Step 2.1: Calculate the time interval T i , A i+1 between the first two adjacent angles A in the N preset scanning angles in the first scanning period; the N preset scanning angles are pre-sorted according to the angles scanned successively within one scanning period of the galvanometer. i ; the N preset scanning angles are pre-sorted according to the angles scanned successively within one scanning period of the galvanometer.

[0054] Step 2.2: Compare T i with T max , where If T i > T max , then sort A i , A i+1 in sequence and put them into the preset scanning angle sequence table of the first scanning period; otherwise, go to step 2.3;

[0055] Step 2.3: Keep A i continuing as the calculation of the preset scanning angle sequence table of the first scanning period, remove A i+1 from the N preset scanning angles and keep it for the calculation of the preset scanning angle sequence table of the second scanning period;

[0056] Step 2.4: Calculate the time interval T i , A i+2 , A i+3 … between the first two adjacent angles in the preset scanning angles calculated in the preset scanning angle sequence table of the first scanning period kept; repeat the operations of steps 2.2 to 2.3 until the preset scanning angle sequence table of the first scanning period is completed; i ; repeat the operations of steps 2.2 to 2.3 until the preset scanning angle sequence table of the first scanning period is completed;

[0057] Step 2.5: Calculate the time interval T between the two adjacent angles among the preset scanning angles retained for the second scanning period in the preset scanning angle sequence table calculation. i ; Repeat the operations in steps 2.2 to 2.4 until the preset scanning angle sequence table for the second scanning period is completed; the preset scanning angles calculated in the preset scanning angle sequence table retained for the second scanning period are also sorted according to the angles scanned successively within one scanning period of the galvanometer.

[0058] Step 2.6: Calculate successively the time interval T between the two adjacent angles among the preset scanning angles calculated in the preset scanning angle sequence table scanned for the third, fourth,... scanning periods in the corresponding scanning periods. i ; Repeat the operations in steps 2.2 to 2.4 to complete the preset scanning angle sequence table for the corresponding scanning period until all the preset scanning angles are covered and completed.

[0059] Further, in step 1, a periodic drive electrical signal is generated by the control circuit to the micro-galvanometer drive circuit to control the micro-galvanometer to perform simple harmonic vibration with a set amplitude A / 2 and a set frequency F.

[0060] Further, in step 3, the logic processing circuit captures the angle feedback electrical signal generated during the vibration of the micro-galvanometer; the light source drive circuit captures the above X_Y electrical pulse signal to drive the light source to generate a pulsed laser beam, and the pulsed laser beam forms a collimated beam through the light emission and reception optical path and is emitted through the micro-galvanometer in the preset angle Y direction of the measured area.

[0061] Further, in step 4, the control circuit receives the first i time-of-flight data of the preset scanning angle Y and stores them in the storage unit with the address X*Y in the storage circuit;

[0062] The first i time-of-flight data of the preset scanning angle Y are obtained through the following process:

[0063] Several optical pulse echo signals returned in the preset angle Y direction of the measured area are converged to the light receiving element through the micro-galvanometer and the light emission and reception optical path or solely through the light emission and reception optical path, the light receiving element generates a photo-induced current, and the time-of-flight readout circuit amplifies the above photo-induced current and converts it into several time-of-flight data of the preset angle Y.

[0064] Further, in step 6, the control circuit sequentially reads all the time-of-flight data of the preset scanning angle of interest Y1 within M1 frame periods stored,

[0065] or the control circuit sequentially reads all the time-of-flight data of the preset non-scanning angle of interest Y2 within M2 frame periods stored.

[0066] The present invention also provides a ranging system for a single-line MEMS lidar, which is characterized in that it includes a laser emitting unit, a micro-mirror unit, a laser receiving unit and a main control unit;

[0067] The micro-mirror unit is optically coupled to the laser emitting unit and the laser receiving unit respectively; the main control unit is electrically connected to the laser emitting unit, the laser receiving unit and the micro-mirror unit respectively;

[0068] The laser emitting unit is used to generate a pulsed laser beam according to the instruction of the main control unit;

[0069] The micro-mirror unit is used to emit the pulsed laser beam to each measured angle in the measured space, and at the same time receive the reflected light pulse echo signals from each angle in the measured space and converge them to the laser receiving unit; it is also used to generate an angle feedback electrical signal during the vibration of the micro-mirror and send it to the main control unit;

[0070] The laser receiving unit is used to convert the received reflected light pulse echo signals from each angle in the measured space into time-of-flight data and send it to the main control unit;

[0071] The main control unit is used to implement the ranging method of the above single-line MEMS lidar.

[0072] Further, the above main control unit includes a logic processing circuit, a control circuit and a storage circuit;

[0073] The logic processing circuit is used to capture in real time the angle feedback electrical signal generated during the vibration of the micro-mirror and convert it into a continuous electrical pulse signal of each preset scanning angle of the lidar, and output the continuous electrical pulse signals of the above scanning angles to the laser emitting unit;

[0074] The control circuit is used to output a periodic driving electrical signal to the micro-mirror unit to make the micro-mirror vibrate in simple harmonic motion with a certain amplitude and period; and is used to calculate the number of scanning cycles N required for the lidar to scan all N preset scanning angles in one frame according to the lidar range D and the micro-mirror parameters T and N T a preset scanning angle sequence table composed of N scanning cycles;

[0075] The control circuit is also used to synchronously receive the synchronous time-of-flight data output by the laser receiving unit;

[0076] The control circuit is also used to sequentially read all the time-of-flight data of the preset scanning angle Y stored in the corresponding frame period; filter the multiple time-of-flight data of the preset scanning angle and use it as the final measured time-of-flight of the preset scanning angle;

[0077] The storage circuit is used to store N with each preset scanning angle as the index address TSeveral time-of-flight data of the preset scanning angle Y in one scanning period.

[0078] Further, the control circuit filters the multiple time-of-flight data of the preset scanning angle and uses it as the final measured time-of-flight of the preset scanning angle. Specifically:

[0079] Perform mean filtering or median filtering on the multiple time-of-flight data of the preset scanning angle and use it as the final measured time-of-flight of the preset scanning angle;

[0080] Or,

[0081] Divide the multiple time-of-flight data of the preset scanning angle into several intervals according to the upper and lower extreme values and a fixed time interval, thereby forming a histogram of the time-of-flight of the preset scanning angle, and use the peak time position of the histogram as the final measured time-of-flight of the preset scanning angle.

[0082] Further, the logic processing circuit is one of FPGA or CPLD logic devices; the control circuit is one of CPU, DSP or MCU devices; the storage circuit is one of SRAM, DRAM or SDRAM storage devices.

[0083] Further, the laser emission unit includes a light source drive circuit and a light source;

[0084] The light source drive circuit is used to capture the electrical pulse signals of each preset scanning angle output by the logic processing circuit and drive the light source to generate pulsed laser beams.

[0085] Further, the micro galvanometer unit includes a transceiver optical path, a micro galvanometer, a micro galvanometer drive circuit and an angle feedback circuit;

[0086] The transceiver optical path is a coaxial optical path, which is used to collimate the pulsed laser beam generated by the light source to the micro galvanometer, and is also used to receive the reflected light pulse echo signal of the measured space on the micro galvanometer and converge it to the laser receiving unit; or, the transceiver optical path is an off-axis optical path, which is used to collimate the laser beam generated by the light source to the micro galvanometer, and is also used to directly receive the echo signal of the measured space and converge it to the laser receiving unit;

[0087] The micro galvanometer drive circuit is used to receive the periodic drive electrical signal output by the control circuit and control the micro galvanometer to perform simple harmonic vibration with a certain amplitude and period according to the drive electrical signal, so that the pulsed laser beam is emitted to each measured angle of the measured space;

[0088] The angle feedback circuit is used to generate an angle feedback electrical signal during the vibration of the micro galvanometer and send it to the logic processing circuit.

[0089] Further, the laser receiving unit includes a light receiving element and a time-of-flight readout circuit;

[0090] The optical receiving element is used to receive a plurality of optical pulse echo signals returned in the preset angle Y direction of the area to be measured and generate a photocurrent.

[0091] The time-of-flight readout circuit is used to amplify the above-mentioned photocurrent and convert it into a plurality of time-of-flight data of the preset angle Y.

[0092] Furthermore, the optical receiving element is an APD, SPAD or SiPM; the time-of-flight readout circuit includes a signal amplification circuit and a time-to-digital conversion circuit or a digital-to-analog conversion circuit.

[0093] The beneficial effects of the present invention are:

[0094] 1. The present invention proposes a ranging method for a single-line MEMS lidar, which filters the single echo measurement data of several vibration cycles of the same vibration angle (measurement angle) of the MEMS galvanometer, such as median filtering, mid-value filtering or forming a histogram of the time of flight, and takes the peak time of the histogram as the final measurement time, and then calculates the measured distance. It improves the anti-interference ability and multi-echo detection ability of the single-line MEMS lidar, greatly reduces the false detection rate, and thus improves the ranging performance of the single-line MEMS lidar.

[0095] 2. The data selection based on different numbers of vibration cycles in the region of interest and the non-region of interest proposed by the present invention improves the flexibility and configurability of the single-line MEMS lidar.

[0096] 3. The ranging method of the single-line MEMS lidar proposed by the present invention has a higher sampling rate compared with the mechanical single-line lidar with the same frame rate, so it has higher reliability. Description of the Drawings

[0097] Figure 1 : Schematic block diagram of the single-line MEMS lidar system;

[0098] Figure 2 : Schematic diagram of the output of the preset angle flag electrical pulse during the micro-galvanometer scanning process;

[0099] Figure 3 : Histogram formed by multiple frame periods at any preset angle;

[0100] The reference numerals in the figure are: 10 - single-line MEMS lidar system, 11 - laser emission unit, 12 - laser reception unit, 13 - micro-mirror unit, 14 - main control unit, 20 - measured space, 112 - light source, 111 - light source drive circuit, 122 - light receiving element, 121 - time-of-flight readout circuit, 132 - micro-mirror, 131 - light emission and reception optical path, 133 - micro-mirror drive circuit, 134 - angle feedback circuit, 141 - logic processing circuit, 142 - control circuit, 143 - storage circuit, 30 - primary echo, 32 - secondary echo, 31 - interference echo. Detailed implementation manners

[0101] The single-line MEMS lidar ranging system of the present invention includes a laser emission unit 11, a micro-mirror unit 13, a laser reception unit 12 and a main control unit 14; the micro-mirror unit 13 is optically coupled to the laser emission unit 11 and the laser reception unit 12 respectively; the main control unit 14 is electrically connected to the laser emission unit 11, the laser reception unit 12 and the micro-mirror unit 13 respectively; the laser emission unit 11 is used to generate a pulsed laser beam according to the instruction of the main control unit; the micro-mirror unit 13 is used to emit the pulsed laser beam to each measured angle of the measured space 20, and simultaneously receive the reflected light pulse echo signals of each angle of the measured space 20 and converge them to the laser reception unit 12; it is also used to generate an angle feedback electrical signal during the vibration of the micro-mirror and send it to the main control unit 14; the laser reception unit 12 is used to convert the received reflected light pulse echo signals of each angle of the measured space 20 into time-of-flight data and send it to the main control unit 14;

[0102] The main control unit 14 is used to complete the following processes to achieve ranging:

[0103] Step 1: Control the micro-mirror to perform simple harmonic vibration according to the set amplitude A / 2 and set frequency F; where A is the overall scanning angle of the lidar;

[0104] Step 2: According to the lidar range D and the micro-mirror parameters, calculate the number of scanning cycles N required for the lidar to scan all N preset scanning angles in one frame T and N T a preset scanning angle sequence table composed of N scanning cycles, and store it; where the number of scanning cycles N T ≥1, N T the time of N scanning cycles is the time for the lidar to scan one frame, which is the frame period; N T The establishment process of the preset scanning angle sequence table composed of N scanning cycles is specifically as follows:

[0105] Step 2.1: Calculate the time interval T between the first adjacent two angles A i , A i+1 in the first scanning cyclei ; N preset scanning angles are sorted in advance according to the angles scanned successively within one scanning cycle of the galvanometer;

[0106] Step 2.2, compare T i with T max , where If T i > T max , then sort A i , A i+1 in sequence and place them in the preset scanning angle sequence list of the first scanning cycle; otherwise, go to Step 2.3;

[0107] Step 2.3, retain A i and continue to be used for the calculation of the preset scanning angle sequence list of the first scanning cycle. Remove A i+1 from the N preset scanning angles and retain it for the calculation of the preset scanning angle sequence list of the second scanning cycle;

[0108] Step 2.4, calculate the time interval T i , A i+2 , A i+3 … between the two adjacent angles in the first scanning cycle among the preset scanning angles calculated; repeat the operations in Steps 2.2 to 2.3 until the preset scanning angle sequence list of the first scanning cycle is completed; i ;

[0109] Step 2.5, calculate the time interval T i between the two adjacent angles in the second scanning cycle among the preset scanning angles calculated for the preset scanning angle sequence list retained in the second scanning cycle; repeat the operations in Steps 2.2 to 2.4 until the preset scanning angle sequence list of the second scanning cycle is completed; the preset scanning angles calculated for the preset scanning angle sequence list retained in the second scanning cycle are also sorted according to the angles scanned successively within one scanning cycle of the galvanometer;

[0110] Step 2.6, successively calculate the time interval T i between the two adjacent angles in the corresponding scanning cycle among the preset scanning angles calculated for the preset scanning angle sequences retained in the third, fourth... scanning cycles; repeat the operations in Steps 2.2 to 2.4 to complete the preset scanning angle sequence lists of the corresponding scanning cycles until all the preset scanning angles are covered and completed.

[0111] Step 3: Capture the angular feedback electrical signal generated by the micromirror during vibration. Combine it with the preset scanning angle sequence table. When the micromirror moves to the Y-th preset scanning angle in the X-th frame period of the preset scanning angle sequence table, output the X_Y electrical pulse signal to drive the light source to generate a pulsed light beam. After collimation, the pulsed light beam is emitted by the micromirror in the direction of the preset scanning angle Y of the area to be measured;

[0112] Step 4: Receive and store the first i time-of-flight data of the preset scanning angle Y; where i is an integer greater than or equal to 1;

[0113] Step 5: Repeat Steps 3 and 4 until the time-of-flight data of N preset scanning angles in M frame periods are stored; where X ≤ M, Y ≤ N;

[0114] Step 6: Sequentially read all the time-of-flight data of the preset scanning angle Y stored within M frame periods; Filter the i*M time-of-flight data of this preset scanning angle and use it as the final measured time-of-flight of this preset scanning angle;

[0115] Step 7: Repeat Step 6 until the processing of the time-of-flight data of all N preset scanning angles for one frame of lidar scanning is completed;

[0116] Step 8: Convert the final time-of-flight of one frame of scanned preset angles output in the above steps into distance information and transmit it to the host device. The upload frame rate is

[0117] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be described in detail below with reference to the accompanying drawings of the specification and specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0118] Many specific details are set forth in the following description to facilitate a thorough understanding of the present invention. However, the present invention may be practiced in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0119] Embodiment 1

[0120] As Figure 1, in this embodiment, the single-line MEMS lidar system 10 includes a laser emission unit 11, a laser reception unit 12, a micro-mirror unit 13 and a main control unit 14. The laser emission unit 11 includes a light source 112 and a light source drive circuit 111. The light source drive circuit 111 is used to drive the light source 112 to generate a pulsed laser beam according to the control instruction of the main control circuit. The laser reception unit 12 includes a light reception element 122 and a time-of-flight readout circuit 121. Among them, the light reception element 122 can be an APD, SPAD, SiPM, etc. The time-of-flight readout circuit 121 includes a signal amplification circuit and a time-to-digital conversion circuit (TDC) or an analog-to-digital conversion circuit (ADC). The light reception element 122 is used to receive a plurality of optical pulse echo signals returned in the preset angle Y direction of the measured area and generate a photo-induced current; the time-of-flight readout circuit 121 is used to amplify and convert the photo-induced current into a plurality of time-of-flight data of the preset angle Y. The micro-mirror unit 13 includes a micro-mirror 132, a transceiver optical path 131, a micro-mirror drive circuit 133, and an angle feedback circuit 134. Among them, the transceiver optical path 131 can be a coaxial optical path, which is used to collimate the laser beam generated by the light source 112 to the micro-mirror 132, and is also used to receive the reflected optical pulse echo signal on the micro-mirror 132 in the measured space 20 to the light reception element 122. The transceiver optical path 131 can also be an off-axis optical path, which is used to collimate the laser beam generated by the light source 112 to the micro-mirror 132, and is also used to directly receive the reflected optical pulse echo signal in the measured space 20 to the light reception element 122. The micro-mirror 132 can be one of single-axis micro-mirrors with electrostatic, electromagnetic or other driving forms. The micro-mirror drive circuit 133 can be one of driving circuits with electrostatic, electromagnetic or other driving forms, which is used to receive the periodic driving electrical signal output by the control circuit 142 and control the micro-mirror 132 to perform simple harmonic vibration with a certain amplitude and period according to the driving electrical signal, so that the pulsed laser beam is emitted to each measured angle of the measured space 20. The angle feedback circuit 134 can be one of photoelectric, capacitive, piezoresistive or other angle feedback circuits, which is used to generate an angle feedback electrical signal during the vibration of the micro-mirror and send it to the logic processing circuit.

[0121] The main control unit 14 includes a logic processing circuit 141, a control circuit 142 and a storage circuit 143. The logic processing circuit 141 can be one of logic devices such as FPGA and CPLD. The control circuit 142 can be one of devices such as CPU, DSP, and MCU. The storage circuit 143 can be one of storage devices such as SRAM, DRAM, and SDRAM. The control circuit 142 is used to output a periodic driving electrical signal to the micro-mirror drive circuit 133 to make the micro-mirror perform simple harmonic vibration with a certain amplitude and period, and is also used to calculate the number of scanning cycle numbers N required for the lidar to scan all N preset scanning angles in one frame according to the lidar range D and the micro-mirror parameters T and NT A preset scan angle sequence table composed of one scan period. The logic processing circuit 141 is used to capture the electrical signals of the angle feedback circuit 134 in real time to generate continuous electrical pulse signals for each preset scan angle of the lidar. The logic processing circuit 141 is also used to output the continuous electrical pulse signals of the above-mentioned scan angles to the light source driving circuit 111.

[0122] The control circuit 142 is also used to synchronously obtain the synchronous time-of-flight data output by the time-of-flight readout circuit 121, and store it in the storage circuit 143 in a block sequence in several galvanometer half-cycles (the time for the galvanometer to move from the forward / reverse maximum amplitude position to the reverse / forward maximum amplitude position, hereinafter referred to as the scan period), and store it in the block with each preset scan angle as the index address. The control circuit 142 is also used to sequentially read all the time-of-flight data of the preset scan angle Y stored within M frame periods; filter the i*M time-of-flight data of the preset scan angle as the final measured time-of-flight of the preset scan angle.

[0123] The ranging method based on the above system in this embodiment includes the following steps:

[0124] Step 1: The control circuit 142 generates a periodic drive electrical signal to the micro-galvanometer drive circuit 133, so that the micro-galvanometer 132 performs a steady-amplitude simple harmonic vibration with a set amplitude A / 2 and a set frequency F. The set amplitude is the optical half-angle of the overall scan angle A of the lidar.

[0125] Step 2: The control circuit 142 calculates the number of scan periods N required to scan all N preset scan angles in one frame according to the lidar range D and the parameters of the micro-galvanometer 132 T and N T a preset scan angle sequence table composed of scan periods, and stores it.

[0126] The N T scan periods are the time for the lidar system to scan one frame, which is the frame period. Among them, the number of scan periods N T ≥1.

[0127] The preset scan angle sequence table needs to satisfy: the time interval T between any two adjacent preset scan angles A i , A i+1 passed successively during the vibration of the micro-galvanometer 132 is greater than the maximum echo flight time T i . To ensure that the echo signal of the optical pulse in the direction of the preset scan angle A max has been received before the optical pulse in the direction of the preset scan angle A i+1 is emitted. Among them, i c is the speed of light. c is the speed of light.

[0128] The N preset scanning angles may be evenly distributed at equal angular intervals or discretely distributed at unequal angular intervals.

[0129] Step 3: The angle feedback circuit 134 generates an angle feedback electrical signal during the vibration of the micro-vibrating mirror 132. The logic processing circuit 141 captures the above electrical signal, and after solving it in combination with the preset scanning angle sequence table, when the micro-vibrating mirror moves to the Y-th preset scanning angle in the preset scanning angle sequence table in the X-th frame period, an X_Y electrical pulse signal is generated.

[0130] Such as Figure 2 , in this embodiment, the preset scanning angles of the lidar are 4, namely A1, A2, A3, A4, T0, T1, T2, T3, T4, T5 are 6 scanning periods, and t1, t2, t3, t4 are the time values corresponding to the angles A1, A2, A3, A4 in the T0 scanning period respectively, and t5, t6 are the time values corresponding to the angles A4, A2 in the T1 scanning period respectively. Combining with the parameters of a certain micro-vibrating mirror satisfying t2 - t1 < T max , t3 - t1 > T max , t4 - t3 < T max , t5 - t3 > T max , t6 - t5 > T max , according to the calculation method in step 2, it can be determined that the frame period is 2 scanning periods, and in this frame period, the preset scanning angle sequence table is A1, A3, A4, A2. 0_0, 0_1, 0_2, 0_3 are the electrical pulse signals indicating the real-time positions of the preset scanning angles A1, A3, A4, A2 in a frame period with X = 0 (including two scanning periods T0, T1), and the angle marking electrical pulses in other frame periods are cyclically output according to the frame period.

[0131] Meanwhile, the light source driving circuit 111 captures the above X_Y electrical pulse signal to drive the light source 112 to generate a pulsed laser beam. The pulsed laser beam forms a collimated beam through the light emitting and receiving optical path 131 and is emitted towards the preset scanning angle Y direction of the measured area 20 through the micro-vibrating mirror 132.

[0132] Step 4: A plurality of optical pulse echo signals returned in the preset scanning angle Y direction of the measured area 20 are converged to the light receiving element 122 through the micro-vibrating mirror 132 and the light emitting and receiving optical path 131 or separately through the light emitting and receiving optical path 131. The light receiving element 122 generates a photo-induced current, and the time-of-flight readout circuit 121 amplifies and converts the photo-induced current into a plurality of time-of-flight data of the preset scanning angle Y.

[0133] Meanwhile, the control circuit 142 temporarily stores the first i time-of-flight data of the preset scanning angle Y in the storage unit at the address X*Y in the storage circuit 143. Where i is an integer greater than or equal to 1; generally, the time-of-flight data of the first two echoes are stored.

[0134] Step 5: Repeat Steps 3 and 4 until the control circuit 142 has stored the time-of-flight data of N preset scanning angles for M frame periods. Where X ≤ M, Y ≤ N;

[0135] Step 6: The control circuit 142 sequentially reads all the time-of-flight data of each preset scanning angle Y within the M frame periods in the storage circuit 143.

[0136] Generally, the 2*M time-of-flight data of this angle can be subjected to mean filtering or median filtering and then used as the final measured time-of-flight of this angle.

[0137] Preferably, the 2*M time-of-flight data of this angle are divided into several intervals according to the upper and lower extreme values and a fixed time interval, thereby forming a histogram of the time-of-flight of this angle, and the peak time position of this histogram is used as the final measured time-of-flight of this angle.

[0138] Generally, the above histogram contains the time-of-flight data of two echoes of this angle. For example Figure 3 is a histogram formed by M frame periods of a certain preset scanning angle, which contains a first echo 30, a second echo 32 and an interference echo 31. The peak time of the histogram formed by the first echo 30 and the second echo 32 is used as the time-of-flight of the two echoes. Generally, the above time interval is 100 ps, that is, the distance resolution is 1.5 cm.

[0139] Step 7: Repeat Step 6 until the processing of the time-of-flight data of all N preset scanning angles is completed.

[0140] Step 8: Convert the final time-of-flight of one frame of preset scanning angle output in the above steps into distance information and transmit it to the host device, and the upload frame rate is

[0141] Embodiment 2

[0142] The single-line MEMS lidar system in this embodiment has the same system composition as that in Embodiment 1, except that the lidar system in this embodiment can configure the user interested area and the non-interested area. In the present invention, the area where the user has a higher frame rate requirement for a certain scanning angle interval is called the user interested area, and vice versa is called the user non-interested area. And the overall scanning angle area of this system is divided into interested and non-interested scanning angles.

[0143] In this embodiment, the lidar system can implement angle histograms with different frame period sizes according to the above different angle intervals. Furthermore, distance information with a high frame rate in the interested area and a low frame rate in the non-interested area can be obtained.

[0144] The ranging method of the present invention based on the above system includes the following steps:

[0145] Step 1: The control circuit 142 generates a periodic driving electrical signal to the micromirror driving circuit 133, so that the micromirror 132 performs a steady-amplitude simple harmonic vibration with a set amplitude A / 2 and a set frequency F.

[0146] The set amplitude is the optical half-angle of the overall scanning angle A of the lidar.

[0147] Step 2: The control circuit 142 calculates the number of scanning cycles N required to scan all N preset scanning angles in one frame according to the lidar range D and the parameters of the micromirror 132 T and N T a preset scanning angle sequence table composed of scanning cycles, and stores it.

[0148] The N T scanning cycle times are the time for the lidar system to scan one frame, which is the frame period. Among them, the number of scanning cycles N T ≥1.

[0149] The preset scanning angle sequence table needs to satisfy that during the vibration of the micromirror 132, the time interval T i between any two adjacent preset scanning angles A i+1 in the table is greater than the maximum echo flight time T i . To ensure that before the light pulse in the direction of the preset scanning angle A max is emitted, the echo signal of the light pulse in the direction of the preset scanning angle A i+1 has been received. Among them, i c is the speed of light. c is the speed of light.

[0150] The N preset scanning angles can be evenly distributed at equal angular intervals or discretely distributed at non-equal angular intervals.

[0151] Step 3: The angle feedback circuit 134 generates an angle feedback electrical signal during the vibration of the micromirror 132. The logic processing circuit 141 captures the above electrical signal, and after combining with the preset scanning angle sequence table for calculation, when the galvanometer moves to the Yth preset scanning angle in the preset scanning angle sequence table in the Xth frame period, an X_Y electrical pulse signal is generated.

[0152] At the same time, the light source driving circuit 111 captures the above X_Y electrical pulse signal to drive the light source 112 to generate a pulsed light beam. The pulsed light beam forms a collimated light beam through the transceiver optical path 131 and is emitted through the micromirror 132 in the direction of the preset scanning angle Y of the measured area 20.

[0153] Step 4: A plurality of optical pulse echo signals returned in the preset scanning angle Y direction of the area 20 to be measured are converged to the optical receiving element 122 through the micro-vibrating mirror 132 and the optical transceiver path 131 or solely through the optical transceiver path 131. The optical receiving element 122 generates a photo-induced current, and the time-of-flight readout circuit 121 amplifies the photo-induced current and converts it into a plurality of time-of-flight data for the preset scanning angle Y.

[0154] Meanwhile, the control circuit 142 temporarily stores the first i time-of-flight data of the above preset scanning angle Y in the storage unit at the address X*Y of the storage circuit 143. Generally, the time-of-flight data of the first two echoes are stored.

[0155] Step 5: Repeat Steps 3 and 4 until the control circuit 142 has stored M1 frame periods, with N1 time-of-flight data for each preset scanning angle of interest per frame period.

[0156] Or, the control circuit 142 stores M2 frame periods, with N2 time-of-flight data for each preset non-scanning angle of interest per frame period.

[0157] Wherein, N1 + N2 = N, which is the total number of preset scanning angles of this system, and M1 < M2;

[0158] Among them, the N1 preset scanning angles of interest and the N2 preset non-scanning angles of interest can be continuous angle intervals or discrete angle combinations respectively.

[0159] Step 6: The control circuit 142 sequentially reads all the time-of-flight data of the preset scanning angle of interest Y1 within M1 frame periods.

[0160] Or, the control circuit 142 sequentially reads all the time-of-flight data of the preset non-scanning angle of interest Y2 within M2 frame periods.

[0161] Generally, the 2*M1 or 2*M2 time-of-flight data of this angle can be subjected to mean filtering or median filtering and then used as the final measured time-of-flight of this angle.

[0162] Preferably, the 2*M1 or 2*M2 time-of-flight data of this angle are divided into several intervals according to the upper and lower extreme values and a fixed time interval, thereby forming a histogram of the time-of-flight of this angle, and the peak time position of this histogram is used as the final measured time-of-flight of this angle.

[0163] Step 7: Repeat Step 6 until the processing of the time-of-flight data of all N1 preset scanning angles of interest or all N2 preset non-scanning angles of interest is completed.

[0164] Step 8: Convert the final flight time of a frame of preset interested or non-interested scanning angles output in the above steps into distance information and transmit it to the host device. The upload frame rate of the preset interested scanning angle is The upload frame rate of the preset non-interested scanning angle is

Claims

1. A ranging method for a single-line MEMS lidar, characterized in that, it includes the following steps: Step 1, control the micro galvanometer to perform simple harmonic vibration according to the set amplitude A / 2 and the set frequency F; where A is the overall scanning angle of the lidar; Step 2: Calculate the number of scanning cycles N required for the lidar to scan all N preset scanning angles in one frame according to the lidar range and the MEMS mirror parameters T and N T a preset scanning angle sequence table composed of scanning cycles, and store it; where the number of scanning cycles N T ≥1, N T The time of the scanning cycles is the time for the lidar to scan one frame, denoted as the frame period; The preset scanning angle sequence table needs to satisfy that during the vibration of the micro-vibrating mirror, the time interval T between any two adjacent preset scanning angles A and A in the preset scanning angle sequence table is greater than the maximum echo flight time T; where D is the range of the lidar and c is the speed of light; i A i+1 is the time interval T i greater than the maximum echo flight time T max ; Among them, D is the range of the lidar and c is the speed of light; Step 3, capture the angle feedback electrical signal generated by the micro galvanometer during vibration, combine it with the preset scanning angle sequence table, and output the X_Y electrical pulse signal when the micro galvanometer moves to the Yth preset scanning angle in the preset scanning angle sequence table in the Xth frame period, drive the light source to generate a pulsed light beam, and after collimation, the pulsed light beam is emitted through the micro galvanometer in the preset scanning angle Y direction of the measured area; Step 4, receive and store the first i flight time data of the preset scanning angle Y; where i is an integer greater than or equal to 1; Step 5, repeat Steps 3 and 4 until the flight time data of N preset scanning angles in M frame periods are stored; where X≤M, Y≤N; Step 6, sequentially read all the flight time data of the preset scanning angle Y within M frame periods; filter the i*M flight time data of this preset scanning angle and use it as the final measured flight time of this preset scanning angle; Step 7, repeat Step 6 until the processing of the flight time data of all N preset scanning angles for one frame of lidar scanning is completed; Step 8: Convert the final flight time of a frame scanned at the preset angle output in the above steps into distance information and transmit it to the host device, and the upload frame rate is 2. The ranging method for a single-line MEMS lidar according to claim 1, characterized in that, the filtering process in Step 6 is specifically: Perform mean filtering or median filtering on the i*M flight time data of this preset scanning angle and use it as the final measured flight time of this preset scanning angle; Or, Divide the i*M flight time data of this preset scanning angle into several intervals according to the upper and lower extreme values and a fixed time interval, thereby forming a histogram of the flight time of this preset scanning angle, and use the peak time position of this histogram as the final measured flight time of this preset scanning angle.

3. The ranging method for a single-line MEMS lidar according to claim 2, characterized in that: The N preset scanning angles are evenly distributed at equal angular intervals or discretely distributed at unequal angular intervals.

4. The ranging method for a single-line MEMS lidar according to claim 3, characterized in that, Step 2 is specifically: Step 2.1: Calculate the time interval T between the first two adjacent angles A i and A i+1 among the N preset scanning angles in the first scanning cycle; the N preset scanning angles are pre-sorted according to the angles scanned by the galvanometer in sequence within one scanning cycle. i ,A i+1 in the first scanning cycle i ; the N preset scanning angles are pre-sorted according to the angles scanned by the galvanometer in sequence within one scanning cycle; Step 2.2, compare T i with T max , where if T i >T max , then sort A i , A i+1 in sequence and place them into the preset scan angle sequence list in the first scan cycle; otherwise, go to Step 2.3; Step 2.3: Retain A i Continue with the calculation of the preset scanning angle sequence list for the first scanning period, and remove A i+1 from the N preset scanning angles, and retain it for the calculation of the preset scanning angle sequence list for the second scanning period; Step 2.4, calculate the preset scanning angle sequence list A reserved for the first scanning cycle i , A i+2 , A i+3 … Calculate the time interval T between the first two adjacent angles in the preset scanning angles calculated in the first scanning cycle i ; Repeat the operations in steps 2.2 to 2.3 until the preset scanning angle sequence list for the first scanning cycle is completed; Step 2.5: Calculate the time interval T between the two adjacent angles in the preset scanning angle calculated in the preset scanning angle sequence table reserved for the second scanning period i ; Repeat the operations in Steps 2.2 to 2.4 until the preset scanning angle sequence table for the second scanning period is completed; The preset scanning angles calculated in the preset scanning angle sequence table reserved for the second scanning period are also sorted according to the angles scanned successively within one scanning period of the galvanometer Step 2.

6. Calculate in sequence the time interval T between the previous adjacent two angles in the corresponding scanning period among the preset scanning angles calculated by retaining the preset scanning angle sequence table scanned in the third, fourth,... scanning periods. i ; Repeat the operations in steps 2.2 to 2.4 to complete the preset scanning angle sequence table for the corresponding scanning period until all the preset scanning angles are covered and completed.

5. The ranging method for a single-line MEMS lidar according to claim 4, characterized in that: In Step 1, a periodic drive electrical signal is generated by the control circuit to the micro galvanometer drive circuit to control the micro galvanometer to perform simple harmonic vibration according to the set amplitude A / 2 and the set frequency F.

6. The ranging method for a single-line MEMS lidar according to claim 4, characterized in that: In Step 3, the logic processing circuit captures the angle feedback electrical signal generated by the micro galvanometer during vibration; the light source drive circuit captures the X_Y electrical pulse signal to drive the light source to generate a pulsed laser beam, and the pulsed laser beam forms a collimated beam through the transceiver optical path and is emitted through the micro galvanometer in the preset angle Y direction of the measured area.

7. The ranging method for a single-line MEMS lidar according to claim 6, characterized in that: In step 4, the control circuit receives the first i time-of-flight data of the preset scanning angle Y and stores them in the storage unit at the address X*Y of the storage circuit; The first i time-of-flight data of the preset scanning angle Y are obtained through the following process: A plurality of optical pulse echo signals returned in the preset angle Y direction of the area to be measured are converged to the optical receiving element through the micro-vibrating mirror and the light emitting and receiving optical path or separately through the light emitting and receiving optical path. The optical receiving element generates a photo-induced current, and the time-of-flight readout circuit amplifies and converts the photo-induced current into a plurality of time-of-flight data of the preset angle Y.

8. The ranging method of the single-line MEMS lidar according to claim 7, characterized in that: In step 6, the control circuit sequentially reads all the time-of-flight data of the preset scanning angle Y stored within M frame periods.

9. A ranging method of a single-line MEMS lidar, characterized in that, it includes the following steps: Step 1, control the micro-vibrating mirror to perform simple harmonic vibration according to the set amplitude A / 2 and the set frequency F; where A is the overall scanning angle of the lidar; Step 2: Calculate the number of scanning cycle N required for the lidar to scan all N preset scanning angles in one frame according to the lidar range and the MEMS mirror parameters T and N T a preset scanning angle sequence table composed of scanning cycles, and store it; where the number of scanning cycles N T ≥1, N T The time of N scanning cycles is the time for the lidar to scan one frame, denoted as the frame period; The preset scanning angle sequence table needs to meet the following condition: during the vibration of the micro-vibrating mirror, when passing through any two adjacent preset scanning angles A i , A i+1 in the preset scanning angle sequence table successively, the time interval T i is greater than the maximum echo flight time T max ; where D is the range of the lidar and c is the speed of light; Step 3, capture the angle feedback electrical signal generated during the vibration of the micro-vibrating mirror, combine it with the preset scanning angle sequence table, and output an X_Y electrical pulse signal when the micro-vibrating mirror moves to the Y-th preset scanning angle in the preset scanning angle sequence table in the X-th frame period, drive the light source to generate a pulsed light beam, and after collimation, the pulsed light beam is emitted through the micro-vibrating mirror in the preset scanning angle Y direction of the area to be measured; Step 4, receive and store the first i time-of-flight data of the preset scanning angle Y; where i is an integer greater than or equal to 1; Step 5, repeat steps 3 and 4 until the time-of-flight data of N1 preset interested scanning angles in M1 frame periods are stored, or, repeat steps 3 and 4 until the time-of-flight data of N2 preset non-interested scanning angles in M2 frame periods are stored; wherein, N1 + N2 = N, N is the number of preset scanning angles, and M1 < M2; Step 6, sequentially read all the time-of-flight data of the preset interested scanning angle Y1 within i*M1 frame periods; filter the i*M1 time-of-flight data of the interested preset scanning angle and use it as the final measured time-of-flight of the preset scanning angle; or, sequentially read all the time-of-flight data of the preset non-interested scanning angle Y2 within i*M2 frame periods; filter the i*M2 time-of-flight data of the non-interested preset scanning angle and use it as the final measured time-of-flight of the preset scanning angle; Step 7, repeat step 6 until the time-of-flight data processing of all N1 preset interested scanning angles or all N2 preset non-interested scanning angles is completed; Step 8: Convert the final flight time of a frame of preset interesting or non-interesting scans at a preset angle into distance information and transmit it to the host device. The upload frame rate for the preset interesting scan angle is The upload frame rate for the preset non-interesting scan angle is 10. The ranging method of the single-line MEMS lidar according to claim 9, characterized in that, the filtering process in step 6 is specifically: Perform mean filtering or median filtering on the i*M1 or i*M2 time-of-flight data of the preset scanning angle and use it as the final measured time-of-flight of the preset scanning angle; or, The i*M1 or i*M2 time-of-flight data of the preset scanning angle are divided into several intervals according to the upper and lower extreme values and a fixed time interval, thereby forming a histogram of the time-of-flight of the preset scanning angle, and the peak time position of the histogram is used as the final measured time-of-flight of the preset scanning angle.

11. The ranging method of the single-line MEMS lidar according to claim 10, characterized in that: the N preset scanning angles are evenly distributed at equal angular intervals or discretely distributed at unequal angular intervals; the N1 preset interested scanning angles and the N2 preset non-interested scanning angles are respectively continuous angular intervals or discrete angular combinations.

12. The ranging method of the single-line MEMS lidar according to claim 11, characterized in that, Step 2 is specifically: Step 2.1: Calculate the time interval T in the first scanning period for the first adjacent two angles A i , A i+1 among N preset scanning angles; the N preset scanning angles are pre-sorted according to the angles scanned successively within one scanning period of the galvanometer; i ​ Step 2.2, compare T i with T max , where if T i >T max , then sort A i , A i+1 in sequence and place them in the preset scan angle sequence list of the first scan cycle; otherwise, proceed to Step 2.3; Step 2.3, retain A i Continue with the calculation of the preset scan angle sequence list for the first scan cycle, and remove A i+1 from the N preset scan angles, and retain it for the calculation of the preset scan angle sequence list for the second scan cycle; Step 2.4: Calculate the preset scan angle sequence list A reserved for the first scan cycle i , A i+2 , A i+3 … Calculate the time interval T between the first two adjacent angles in the preset scan angles for the first scan cycle i ; Repeat the operations in steps 2.2 to 2.3 until the preset scan angle sequence list for the first scan cycle is completed; Step 2.5: Calculate the time interval T between the first two adjacent angles among the preset scanning angles calculated in the preset scanning angle sequence table retained until the second scanning period. i ; Repeat the operations in steps 2.2 to 2.4 until the preset scanning angle sequence table for the second scanning period is completed; the preset scanning angles calculated in the preset scanning angle sequence table retained until the second scanning period are also sorted according to the angles scanned successively within one scanning period of the galvanometer. Step 2.

6. Calculate in sequence the time interval T between the previous adjacent two angles in the corresponding scanning cycle among the preset scanning angles calculated by retaining the preset scanning angle sequence table scanned in the third, fourth,... scanning cycles. i Repeat the operations in Steps 2.2 to 2.4 to complete the preset scanning angle sequence table for the corresponding scanning cycle until all the preset scanning angles are covered and completed.

13. The ranging method of the single-line MEMS lidar according to claim 12, characterized in that: In step 1, a periodic driving electrical signal is generated by the control circuit to the micro-mirror driving circuit to control the micro-mirror to perform simple harmonic vibration according to the set amplitude A / 2 and the set frequency F.

14. The ranging method of the single-line MEMS lidar according to claim 13, characterized in that: In step 3, the logic processing circuit captures the angle feedback electrical signal generated by the micro-mirror during vibration; the light source driving circuit captures the X_Y electrical pulse signal to drive the light source to generate a pulsed laser beam, and the pulsed laser beam forms a collimated beam through the light emitting and receiving optical path and is emitted through the micro-mirror in the preset angle Y direction of the measured area.

15. The ranging method of the single-line MEMS lidar according to claim 14, characterized in that: In step 4, the control circuit receives the first i time-of-flight data of the preset scanning angle Y and stores them in the storage unit with the address X*Y in the storage circuit; The first i time-of-flight data of the preset scanning angle Y are obtained through the following process: Several optical pulse echo signals returned in the preset angle Y direction of the measured area are converged to the light receiving element through the micro-mirror and the light emitting and receiving optical path or separately through the light emitting and receiving optical path, the light receiving element generates a photo-induced current, and the time-of-flight readout circuit amplifies the photo-induced current and converts it into several time-of-flight data of the preset angle Y.

16. The ranging method of the single-line MEMS lidar according to claim 15, characterized in that: In step 6, the control circuit sequentially reads all the time-of-flight data of the preset interested scanning angle Y1 within M1 frame periods, or the control circuit sequentially reads all the time-of-flight data of the preset non-interested scanning angle Y2 within M2 frame periods.

17. A ranging system for a single-line MEMS lidar, characterized in that: comprising a laser emitting unit (11), a micro-mirror unit (13), a laser receiving unit (12) and a main control unit (14); The micro-mirror unit (13) is optically coupled to the laser emitting unit (11) and the laser receiving unit (12) respectively; the main control unit (14) is electrically connected to the laser emitting unit (11), the laser receiving unit (12) and the micro-mirror unit (13) respectively; The laser emitting unit (11) is used to generate a pulsed laser beam according to the instructions of the main control unit; The micro galvanometer unit (13) is used to emit the pulsed laser beam to each measured angle of the measured space (20), and at the same time receive the reflected light pulse echo signals from each angle of the measured space (20) and converge them to the laser receiving unit (12); It is also used to generate an angular feedback electrical signal during the vibration of the micro galvanometer and send it to the main control unit (14); The laser receiving unit (12) is used to convert the received reflected light pulse echo signals from each angle of the measured space (20) into time-of-flight data and send it to the main control unit (14); The main control unit (14) is used to implement the ranging method of the single-line MEMS lidar according to claim 1 or 9.

18. The ranging system of the single-line MEMS lidar according to claim 17, characterized in that: The main control unit (14) includes a logic processing circuit (141), a control circuit (142) and a storage circuit (143); The logic processing circuit (141) is used to capture in real time the angular feedback electrical signal generated during the vibration of the micro galvanometer and convert it into a continuous electrical pulse signal for each preset scanning angle of the lidar, and output the continuous electrical pulse signals for each scanning angle to the laser emitting unit (11); The control circuit (142) is configured to output a periodic driving electrical signal to the micro-mirror unit (13) to cause the micro-mirror to perform simple harmonic vibration with a certain amplitude and period; and is configured to calculate the number of scanning periods N required for the lidar to scan all N preset scanning angles in one frame according to the lidar range D and the micro-mirror parameters T and N T a preset scanning angle sequence table composed of scanning periods; The control circuit (142) is also used to synchronously receive the synchronous time-of-flight data output by the laser receiving unit (12); The control circuit (142) is also used to sequentially read all the time-of-flight data of the preset scanning angle Y within the corresponding frame period; Filter the multiple time-of-flight data of the preset scanning angle and use it as the final measured time-of-flight of the preset scanning angle; The storage circuit (143) is used to store a plurality of time-of-flight data of the preset scanning angle Y in each scanning period with each preset scanning angle as the index address T for N 19. The ranging system of the single-line MEMS lidar according to claim 18, characterized in that: The control circuit filters the multiple time-of-flight data of the preset scanning angle and uses it as the final measured time-of-flight of the preset scanning angle specifically as: Filter the multiple time-of-flight data of the preset scanning angle by mean filtering or median filtering and use it as the final measured time-of-flight of the preset scanning angle; Or, Divide the multiple time-of-flight data of the preset scanning angle into several intervals according to the upper and lower extreme values and a fixed time interval, thereby forming a histogram of the time-of-flight of the preset scanning angle, and use the peak time position of the histogram as the final measured time-of-flight of the preset scanning angle.

20. The ranging system of the single-line MEMS lidar according to claim 19, characterized in that: The logic processing circuit (141) is one of FPGA or CPLD logic devices; The control circuit (142) is one of CPU, DSP or MCU devices; The storage circuit (143) is one of SRAM, DRAM or SDRAM storage devices.

21. The ranging system of the single-line MEMS lidar according to claim 19, characterized in that: The laser emitting unit (11) includes a light source driving circuit (111) and a light source (112); The light source driving circuit (111) is used to capture the electrical pulse signals of each preset scanning angle output by the logic processing circuit (141) and drive the light source (112) to generate pulsed laser beams.

22. The ranging system of the single-line MEMS lidar according to claim 19, wherein: The micro-mirror unit (13) includes an optical transceiver path (131), a micro-mirror (132), a micro-mirror driving circuit (133) and an angle feedback circuit (134); The optical transceiver path (131) is a coaxial optical path, which is used to collimate the pulsed laser beam generated by the light source (112) to the micro-mirror (132), and is also used to receive the reflected light pulse echo signal of the measured space (20) on the micro-mirror (132) and converge it to the laser receiving unit; or, the optical transceiver path (131) is an off-axis optical path, which is used to collimate the laser beam generated by the light source (112) to the micro-mirror (132), and is also used to directly receive the echo signal of the measured space (20) and converge it to the laser receiving unit; The micro-mirror driving circuit (133) is used to receive the periodic driving electrical signal output by the control circuit (142), and control the micro-mirror (132) to perform simple harmonic vibration with a certain amplitude and period according to the driving electrical signal, so that the pulsed laser beam is emitted to each measured angle of the measured space (20); The angle feedback circuit (134) is used to generate the angle feedback electrical signal during the vibration of the micro-mirror and send it to the logic processing circuit.

23. The ranging system of the single-line MEMS lidar according to claim 19, wherein: The laser receiving unit (12) includes a light receiving element (122) and a time-of-flight readout circuit (121); The light receiving element (122) is used to receive a plurality of light pulse echo signals returned in the preset angle Y direction of the measured area and generate a photo-induced current; The time-of-flight readout circuit (121) is used to amplify the photo-induced current and convert it into a plurality of time-of-flight data of the preset angle Y.

24. The ranging system of the single-line MEMS lidar according to claim 23, wherein: The light receiving element (122) is an APD, SPAD or SiPM; the time-of-flight readout circuit (121) includes a signal amplification circuit and a time-to-digital conversion circuit or a digital-to-analog conversion circuit.

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