A multi-beam laser ranging sensor based on TOF

Abstract

The present invention provides a multi-beam laser ranging sensor based on TOF, comprising a digital processing unit, a laser emitting unit, an optical system unit and a laser receiving unit; the laser emitting unit is used to emit at least three lasers according to the laser emitting signal sent by the digital processing unit; the optical system unit is used to focus each laser to the object to be measured, and focus the laser reflected by the object to be measured to the laser receiving unit; the laser receiving unit is used to generate a laser receiving signal based on the received laser, and send it to the digital processing unit; the digital processing unit is used to obtain the distance from the corresponding laser to the object to be measured based on the laser emitting signal and the laser receiving signal. The multi-beam laser ranging sensor based on TOF of the present invention solves the problems of low frequency and resolution of existing laser measurement, unclear object contour and narrow detection field of view through multi-beam laser ranging.

Description

Technical Field

[0001] The present invention relates to the technical field of laser distance measuring sensors, and in particular to a multi-beam laser distance measuring sensor based on time of flight (TOF). Background Art

[0002] TOF technology refers to the sensor emitting modulated near-infrared light, which is reflected after encountering an object. The sensor calculates the time difference or phase difference between the emission and reflection of the light, and converts the distance of the object according to the time difference or phase difference to generate depth information. In addition, combined with the energy intensity of the echo reflected by the object and the measurement distance, the three-dimensional outline of the object can be presented in the form of a topographic map with different colors representing different distances.

[0003] In the prior art, most TOF-based laser ranging sensors use single-beam laser emission as the measurement core. Among them, a single-beam laser ranging sensor projects a laser point on the surface of an object to measure the distance from the current object to the ranging center. It is more widely used in security engineering and other aspects. With the development of the laser radar field, single-line laser ranging can no longer meet operational needs, such as automatic guided vehicle (Automated Guided Vehicle, AGV) navigation and obstacle avoidance, unmanned aerial vehicle (Unmanned Aerial Vehicle, UAV) height determination and mapping, security monitoring, and unmanned assisted driving of automobiles. These applications require laser ranging sensors to be able to respond to the front environment and object status in real time and at high speed in three dimensions or more details. Summary of the invention

[0004] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a TOF-based multi-beam laser ranging sensor, which solves the problems of low frequency and resolution of existing laser measurement, unclear object contours, and narrow detection field of view through multi-beam laser ranging.

[0005] To achieve the above-mentioned purpose and other related purposes, the present invention provides a TOF-based multi-beam laser ranging sensor, comprising a digital processing unit, a laser emitting unit, an optical system unit and a laser receiving unit; the laser emitting unit is connected to the digital processing unit, and is used to emit at least three lasers according to the laser emitting signal sent by the digital processing unit; the optical system unit is connected to the laser emitting unit and the laser receiving unit, and is used to focus each laser onto the object to be measured, and focus the laser reflected back from the object to be measured onto the laser receiving unit; the laser receiving unit is connected to the optical system unit and the digital processing unit, and is used to generate a laser receiving signal based on the received laser, and send it to the digital processing unit; the digital processing unit is used to obtain the distance from the corresponding laser to the object to be measured based on the laser emitting signal and the laser receiving signal.

[0006] In one embodiment of the present invention, the digital processing unit includes an FPGA module and a TOF time-of-flight measurement circuit; the TOF time-of-flight measurement circuit is used to calculate the time difference between the laser emission signal and the laser reception signal; the FPGA module is used to generate a laser emission signal and send it to the laser emission unit, and calculate the distance between the corresponding laser and the object to be measured based on the time difference.

[0007] In one embodiment of the present invention, the laser emitting unit includes a laser driving circuit and an array laser diode; the array laser diode includes at least three laser diodes arranged in parallel up and down; the laser driving circuit is used to generate a driving signal for the laser diode based on the laser emission signal to drive each laser diode to emit laser in a time-sharing manner;

[0008] The laser receiving unit includes an array APD diode and a laser receiving circuit; the array APD diode includes at least three APD diodes arranged in parallel up and down, and the arrangement order of the APD diodes and the laser diodes corresponds one to one; each APD diode is used to receive the laser emitted by the corresponding laser diode, and the laser receiving circuit is used to generate a laser receiving signal and output it to the digital processing unit.

[0009] In one embodiment of the present invention, the laser driving circuit includes a single high-speed driving circuit and a laser diode control circuit corresponding one to one with the laser diode; the high-speed driving circuit is used to generate a laser diode driving signal based on the laser emission signal; the laser diode control circuit is used to control the opening and closing of the corresponding laser diode to achieve time-sharing conduction of multiple laser diodes.

[0010] In one embodiment of the present invention, the laser receiving circuit includes an I / V circuit, a gain amplifier circuit, a constant ratio timing circuit and a digital shaping circuit; the I / V circuit is used to convert the current signal output by the APD diode into a voltage signal; the gain amplifier circuit is used to amplify the voltage signal; the constant ratio timing circuit and the digital shaping circuit are used to perform constant ratio timing and digital shaping on the amplified voltage signal, respectively.

[0011] In one embodiment of the present invention, the laser diodes in the laser diode array are arranged vertically at a preset angle; and the APD diodes in the APD diode array are arranged vertically at the preset angle.

[0012] In one embodiment of the present invention, the number of the laser diodes and the APD diodes is 3-16.

[0013] In one embodiment of the present invention, the optical system unit includes a transmitting mirror and a receiving mirror; the transmitting mirror is used to focus the laser emitted by the laser diode onto the object to be measured; the receiving mirror is used to focus the laser reflected back from the object to be measured onto the APD diode corresponding to the laser diode.

[0014] In one embodiment of the present invention, a system compensation unit is also included, which is connected to the laser receiving unit and the digital processing unit, and includes a temperature compensation circuit and an APD high-voltage compensation circuit; the temperature compensation circuit is used to collect temperature information of the array APD diode and output it to the digital processing unit; the APD high-voltage compensation circuit is used to generate DC high voltage to drive the array APD diode, and collect voltage information on the array APD diode and output it to the digital processing unit; the digital processing unit is also used to perform temperature compensation and high-voltage compensation on the array APD diode based on the temperature information, and correct the DC high voltage according to the voltage information.

[0015] In one embodiment of the present invention, the laser emission signal is a narrow pulse signal, and the frequency of the narrow pulse signal is evenly distributed to each laser diode as the driving frequency of the laser diode.

[0016] As described above, the TOF-based multi-beam laser ranging sensor of the present invention has the following beneficial effects:

[0017] (1) With the adoption of optical structure and circuit design, the laser emitting unit will only drive one laser diode at the same time. At the same time, based on the receiving angle between the avalanche photodiode (APD) of the receiving unit and the laser diode (LD) of the emitting unit, the APD energy of the receiving unit is guaranteed to be the largest at the same time, and multiple APD outputs are connected in parallel to increase the sensitivity of the receiving end; and based on the algorithm, it is determined whether the received signal is valid at that moment, thereby ensuring the usefulness of the signal;

[0018] (2) It has the characteristics of three-dimensional space measurement and can realize multiple laser beams emission and multiple laser beams reception. Each laser emission circuit corresponds to a laser receiving circuit. The laser transceiver devices correspond to each other and are arranged at a certain angle up and down. In the case of horizontal scanning, a three-dimensional graph can be formed;

[0019] (3) It has the characteristics of wide field of view detection, and can detect target distance within a field of view of up to 30 degrees, with the center angle of 0 and the maximum angle range of up and down arrangement of 15 degrees;

[0020] (4) It has the characteristics of ultra-high-speed ranging. Multiple laser beams can drive each laser diode at a frequency of 20 kHz at a frequency of 320 kHz, and each laser diode does not interfere with each other. The maximum number of ranging times per second can reach 3,200,000;

[0021] (5) Compared with the traditional multi-line receiving circuit, it has the characteristics of simple circuit, low cost, high reliability and small size;

[0022] (6) It uses a high-speed FPGA module as the core control unit, and has multiple TOF measurement channels outside. The high-speed FPGA module controls the measurement and data output. It is suitable for 3-16 time difference measurement channels and can measure multiple laser flight time differences at the same time. It has the characteristics of multi-channel high-speed measurement.

[0023] (7) Applicable to high-speed multi-line LiDAR industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic structural diagram of a multi-beam laser ranging sensor based on TOF in one embodiment of the present invention;

[0025] Figure 2 Shown is a schematic structural diagram of a laser emitting unit of the present invention in one embodiment;

[0026] Figure 3 It is a timing diagram of a narrow pulse signal and a clock signal in one embodiment of the present invention;

[0027] Figure 4It is a timing diagram of the narrow pulse signal of the present invention and the driving signal on each laser diode in one embodiment;

[0028] Figure 5 It is a schematic diagram showing the working principle of the optical system unit of the present invention in one embodiment;

[0029] Figure 6 Shown is a timing diagram of the laser flight start measurement signal and the time difference flight signal in one embodiment of the present invention.

[0030] Component number description

[0031] 1 Digital Processing Unit

[0032] 11FPGA module

[0033] 12TOF time difference of flight measurement circuit

[0034] 2 laser emission units

[0035] 21 Laser driving circuit

[0036] 211 high speed drive circuit

[0037] 212 Laser Diode Control Circuit

[0038] 22 laser diode arrays

[0039] 3Optical system unit

[0040] 31 Emission mirror

[0041] 32 receiving mirror

[0042] 4 Laser receiving unit

[0043] 41 APD diode array

[0044] 42 Laser receiving circuit

[0045] 5System compensation unit

[0046] 51 Temperature compensation circuit

[0047] 52APD high voltage compensation circuit DETAILED DESCRIPTION

[0048] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0049] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and thus the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0050] The TOF-based multi-beam laser ranging sensor of the present invention solves the problems of low frequency and resolution of existing laser measurements, unclear object contours, and narrow detection field of view through multi-beam laser ranging, can achieve ultra-high-speed ranging, and only uses a single receiving circuit, has a simple structure, low cost, and is extremely practical.

[0051] like Figure 1 As shown, in one embodiment, the TOF-based multi-beam laser ranging sensor of the present invention includes a digital processing unit 1 , a laser emitting unit 2 , an optical system unit 3 and a laser receiving unit 4 .

[0052] The laser emitting unit 2 is connected to the digital processing unit 1 , and is used to emit at least three laser beams according to the laser emitting signal sent by the digital processing unit 1 .

[0053] Specifically, the digital processing unit 1 sends a narrow pulse signal as a laser emission signal to the laser emission unit 2. In one embodiment of the present invention, Figure 2 As shown, the laser emitting unit 2 includes a laser driving circuit 21 and an array laser diode 22, so as to realize the time-sharing continuous emission of multiple laser diodes. Among them, the array laser diode 22 includes at least three laser diodes arranged in parallel up and down; the laser driving circuit 21 is used to generate a driving signal of the laser diode based on the laser emission signal to drive each laser diode to emit laser in time. Preferably, the array laser diode 22 includes 3-16 SMD patch pulse laser diodes, which are arranged at a certain acute angle up and down, and the field of view angle (i.e., the angle of the two laser diodes at the upper and lower edges) is up to 30 degrees, and the field of view is arranged with a center angle of 0 degrees and a field of view of plus or minus 15 degrees up and down. Depending on the number of laser diodes, the angular resolution of each two adjacent laser diodes is 1°-10°.

[0054] In one embodiment of the present invention, the laser driving circuit 21 includes a single high-speed driving circuit 211 and a laser diode control circuit 212 corresponding to the laser diode one by one; the high-speed driving circuit 211 is used to generate a laser diode driving signal based on the laser emission signal; the laser diode control circuit 212 is used to control the opening and closing of the corresponding laser diode to realize the time-sharing conduction of multiple laser diodes. With the cooperation of multiple laser diode control circuits, the time-sharing conduction of multiple laser diodes is realized, and each path generates a certain phase time difference, so that multiple laser diodes take turns to continuously emit laser signals without interfering with each other; specifically, the narrow pulse signal is connected to the PWM port of the laser emission unit 2, and its frequency is 60khz-320khz. The specific frequency is determined according to the number of laser diodes, and it is necessary to ensure that the driving frequency of each laser diode after frequency division is 20khz. The 60-320khz narrow pulse signal is amplified by the high-speed driving circuit, and the output signal is connected to the anode of the array laser diode 22. At the same time, the digital processing unit 1 generates 3-16 clock signals, and each of them is 20khz, the high level time is longer than the narrow pulse time, and the output end is connected to G1G2G3....Gn of the laser emitting unit 2. The output time of each clock signal is different, and the interval between adjacent time difference rising edges is Ta. Its control timing is as follows Figure 3 As shown. Where Tz1 is the narrow pulse width, ts is the time interval between the rising edge of the clock signal and the rising edge of the PWM, ta is the time interval between the rising edges of the adjacent clock signals, and Tz2 is the high level time of the clock signal. The clock signals on G1-Gn control the conduction of the array laser diodes 22 in turn through the 3-16 laser diode control circuits, so that each laser diode is turned on.

[0055] The switching frequency reaches 20 kHz. Finally, the driving frequency of each laser diode is as follows Figure 4 shown.

[0056] The laser receiving unit 4 is connected to the optical system unit 3 and the digital processing unit 1, and is used to generate a laser receiving signal based on the received laser and send it to the digital processing unit 1. Specifically, the laser receiving unit 4 includes an array APD diode 41 and a laser receiving circuit 42; the array APD diode includes at least three APD diodes arranged in parallel, and the APD diodes correspond to the arrangement order of the laser diodes one by one; each APD diode is used to receive the laser emitted by the corresponding laser diode, and the laser receiving circuit 42 is used to generate a laser receiving signal and output it to the digital processing unit 1. Preferably, the array APD diode 41 includes 3-16 patch APD diodes, and is arranged at a certain angle up and down, and its arrangement angle is the same as that of the laser diode in the laser emitting unit 2, and its maximum receiving field angle is 30°, the maximum angle resolution of adjacent APD diodes is 2°, and the arrangement angle error is guaranteed to be accurate to ±0.05°. Multiple APD diodes are arranged in parallel, and the output ends of multiple APD diodes are connected to the laser receiving circuit 42 after intersecting in parallel. After the laser from the laser emitting unit 2 is reflected by the measured object, part of the signal is received by the array APD diode, and each APD diode can ensure that it receives the laser signal emitted by the corresponding laser diode. Multiple APD diodes are connected in parallel, which can also increase the sensitivity of the received signal, thereby having good stability.

[0057] In one embodiment of the present invention, the laser receiving circuit 42 includes an I / V circuit, a gain amplifier circuit, a constant ratio timing circuit and a digital shaping circuit; the I / V circuit is used to convert the current signal output by the APD diode into a voltage signal; the gain amplifier circuit is used to amplify the voltage signal; the constant ratio timing circuit and the digital shaping circuit are used to perform constant ratio timing and digital shaping on the amplified voltage signal, respectively. Specifically, the weak current signal from the array APD diode is converted into a recognizable voltage signal through I / V, and then amplified to a stable voltage signal that is sufficiently recognizable and usable, and finally subjected to constant ratio timing and shaping, so that the signal is more stable and useful, so as to be input into the digital processing unit 1.

[0058] The optical system unit 3 is connected to the laser emitting unit 2 and the laser receiving unit 4 , and is used to focus each laser beam onto the object to be measured, and to focus the laser beam reflected by the object to be measured onto the laser receiving unit 4 .

[0059] like Figure 5As shown, in one embodiment of the present invention, the optical system unit 3 includes a transmitting mirror 31 and a receiving mirror 32; the transmitting mirror 31 is used to focus the laser emitted by the laser diode to the object to be measured; the receiving mirror 32 is used to focus the laser reflected by the object to be measured to the APD diode corresponding to the laser diode. Specifically, the transmitting mirror 31 is composed of high-precision optical collimating lenses, which can focus 3-16 scattered lasers into 3-16 small dots of the same size and arranged at a certain angle up and down, and the spot energy can be projected within a range of 100-200 meters. When multiple lasers emit lasers, part of the signal after diffuse reflection returns to the receiving mirror 32. The receiving mirror 32 projects each laser on the APD diode corresponding to the laser diode, thereby realizing one-to-one laser reception.

[0060] Specifically, Figure 6 As shown, the laser diode LD1 emits a 20khz pulse signal and generates a laser flight start measurement signal START1, which is focused into a laser point through the transmitting mirror 31 and projected onto the surface of the object to be measured at a certain angle. After diffuse reflection from the object to be measured, part of the energy is focused on the receiving mirror 32. Since the laser diode LD1 and the APD diode APD1 are installed at the same angle and are parallel to each other, the laser can ensure that the APD diode APD1 can receive sufficient return energy after being reflected by the object to be measured. Since the anodes of multiple APD diodes are connected in parallel, according to the diffuse reflection and optical characteristics of the object, the APD diodes APD2, APD3...APDn can also receive a very small part of the energy. If the energy is set to be expressed in dB, then dBapd1>dBapd2>dBapd3...>dBapdn. Therefore, the final output current of the array APD diode is I=Iapd1+Iapd2+Iapd3.....+Iapdn, thereby increasing the output current and improving the sensitivity. The above formula can be expressed as In=IAPDn+IAPDe, where In is the current output by the array APD diode when the laser diode LDn emits, IADPn is the current received by APDn after the laser diode LDn emits back, and IAPDe is the current signal output by other adjacent APD diodes. Ideally, this current is 0.

[0061] The current In input is amplified by the laser receiving circuit 42, and finally the time difference flight signal STOP is output, so that the flight time difference t1 can be obtained for the digital processing unit 1 to calculate the distance D1; similarly, when the laser diode LD2 is emitted, it is ensured that the APD diode APD2 can receive the laser signal to obtain the flight time difference t2 and calculate the distance D2.

[0062] The digital processing unit 1 is used to obtain the distance from the corresponding laser to the measured object based on the laser emission signal and the laser reception signal.

[0063] In one embodiment of the present invention, the digital processing unit 1 includes an FPGA module 11 and a TOF time difference of flight measurement circuit 12. The TOF time difference of flight measurement circuit 12 is used to calculate the time difference between the laser emission signal and the laser reception signal; the FPGA module 11 is used to generate a laser emission signal and send it to the laser emission unit, and calculate the distance between the corresponding laser and the object to be measured according to the time difference.

[0064] Specifically, the TOF time-of-flight measurement circuit includes multiple or multi-channel high-speed time-of-flight measurement ICs and peripheral circuits, which are used to calculate the time-of-flight according to the laser flight start measurement signal START and the time-of-flight signal STOP. The output end of the laser receiving circuit 42 is directly connected to the TDC time-of-flight measurement circuit 12, and the laser receiving circuit 42 outputs 20k-320k measurement pulses per second, and the TDC time-of-flight measurement circuit 12 measures 3-16 laser echo signals each time.

[0065] Specifically, the FPGA module 11 calculates the distance between the corresponding laser and the measured object according to the flight time difference. The FPGA module 11 includes an ultra-high-speed FPGA core controller and other peripheral circuits, which are mainly responsible for generating a 60khz-320khz high-precision narrow pulse signal, and outputting it to the laser emitting unit 2, so that the laser diode control circuit of the laser emitting unit 2 controls the opening and closing of a single laser diode; at the same time, the time difference result from the TDC flight time difference measurement circuit is read at high speed, and data processing is performed according to the algorithm. Preferably, the FPGA module 11 adopts ACTEL's unique SmartFusion series controller, which has an efficient Cortex-M3 core, the internal M3 operating frequency is as high as 100Mhz, and has 2M RAM inside, including rich AD / DA interfaces. M3 is closely connected with the FPGA control logic, which makes the data throughput higher and further enhances the confidentiality of the system software algorithm.

[0066] In one embodiment of the present invention, the TOF-based multi-beam laser ranging sensor of the present invention further includes a system compensation unit 5, which is connected to the laser receiving unit 4 and the digital processing unit 1, and includes a temperature compensation circuit 51 and an APD high-voltage compensation circuit 52. The temperature compensation circuit 51 is used to collect temperature information of the array APD diode 41 and send it to the digital processing unit 1; the APD high-voltage compensation circuit 52 is used to generate a DC high voltage to drive the array APD diode 41, and collect the voltage information on the array APD diode 41 and send it to the digital processing unit 1; the digital processing unit 1 is also used to perform temperature compensation and high-voltage compensation on the array APD diode 22 based on the temperature information.

[0067] compensation, and correcting the DC high voltage according to the voltage information.

[0068] Specifically, the temperature compensation circuit 51 is connected to the digital processing unit 1, and is used to detect the temperature changes of the array APD diode 41 and the system, and transmit the detected temperature information to the digital processing unit 1 in real time. Among them, the temperature sensor in the temperature compensation circuit 51 is close to the array APD diode 41, accurately detects the temperature changes on the array APD diode 41, and can also detect the overall temperature changes of the laser receiving unit 4 in real time. The output of the temperature compensation circuit 51 is connected to the ADC unit inside the FPGA module 11, and the temperature information is sent to the FPGA module 11, so that the FPGA module 11 uses the software algorithm to perform temperature algorithm compensation.

[0069] The APD high-voltage compensation circuit 52 is connected to the digital processing unit 1, and is used to generate a 50V-200V high-voltage DC power supply to drive the APD array diode 41; at the same time, the high-voltage information of the upper end of the array APD diode 41 is collected, and the collected high-voltage information is fed back to the FPGA module 11, and the FPGA module 11 performs high-voltage compensation on the array APD diode 41 according to the temperature information transmitted by the temperature detection circuit, and controls the output size of the high-voltage DC according to the high-voltage information fed back by the APD high-voltage compensation circuit 52, so that the array APD diode 41 can maintain the best working state under various ambient temperatures, and can have the best gain under different ambient temperatures, so as to better receive the echo to ensure signal stability. Specifically, the APD high-voltage compensation circuit 52 can output a DC high-voltage of 50V-200V, a driving capability of 10mA, as low as 50mV power supply ripple, and the output high voltage is adjustable, and its adjustment resolution can reach 0.3V, and its output end is directly connected to the reverse end of the array APD diode 41, and 3-16 APD diodes can be driven to work at the same time.

[0070] In the present invention, the APD high-voltage compensation circuit 52 is closely linked with the temperature compensation circuit 51. When the temperature sensor in the temperature compensation circuit 51 detects the temperature change of the laser receiving unit 4 and transmits the temperature information to the FPGA module 11, the FPGA module 11 controls the APD high-voltage compensation circuit 52 to perform high-voltage compensation on the array APD diode 41.

[0071] In summary, the TOF-based multi-beam laser ranging sensor of the present invention adopts an optical structure and circuit design. At the same time, the laser emitting unit will only drive one laser diode. At the same time, based on the receiving angle between the APD of the receiving unit and the LD of the emitting unit, it is ensured that the APD energy of the receiving unit is the largest at the same time, and multiple APD outputs are connected in parallel, which increases the sensitivity of the receiving end; and based on the algorithm, it is judged whether the received signal is valid at that moment to ensure the usefulness of the signal; it has the characteristics of three-dimensional space measurement, and can realize multi-beam laser emission and multi-beam laser reception. Each laser emitting diode corresponds to a laser receiving diode, and the laser transceiver devices correspond to each other one by one and are arranged at a certain angle up and down, and can form a three-dimensional figure in the case of horizontal scanning; it has the characteristics of wide field of view detection, maximum It can detect the target distance within a 30-degree field of view, with a central angle of 0 and a maximum angle range of 15 degrees arranged up and down; it has the characteristics of ultra-high-speed ranging, and multiple laser beams can drive each laser diode at a frequency of 20khz at a frequency of 320kz in turn, and each laser diode does not interfere with each other, and can reach up to 3,200,000 ranging times per second; compared with the traditional multi-line receiving circuit, it has the characteristics of simple circuit, low cost, high reliability, and small size; it uses a high-speed FPGA module as the control core unit, and has multiple TOF measurement channels on the outside, and its measurement and data output are controlled by the high-speed FPGA module respectively, which is suitable for 3-16 time difference measurement channels, and can simultaneously measure the time difference of multi-channel laser flight, and has the characteristics of multi-channel high-speed measurement; it is suitable for the high-speed multi-line laser radar industry. Therefore, the present invention effectively overcomes the various shortcomings in the prior art and has a high industrial utilization value.

[0072] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A multi-beam laser ranging sensor based on TOF, characterized in that: It includes a digital processing unit, a laser emitting unit, an optical system unit and a laser receiving unit; The laser emitting unit is connected to the digital processing unit and is used to emit at least three laser beams according to the laser emitting signal sent by the digital processing unit; wherein the laser emitting unit comprises a laser driving circuit and an array laser diode; the array laser diode comprises at least three laser diodes arranged in parallel; the laser driving circuit is used to generate a driving signal for the laser diode based on the laser emitting signal to drive each laser diode to emit laser beams in a time-sharing manner; The optical system unit is connected to the laser emitting unit and the laser receiving unit, and is used to focus each laser onto the object to be measured, and to focus the laser reflected by the object to be measured onto the laser receiving unit; The laser receiving unit is connected to the optical system unit and the digital processing unit, and is used to generate a laser receiving signal based on the received laser, and send it to the digital processing unit; wherein the laser receiving unit includes an array APD diode and a laser receiving circuit; the array APD diode includes at least three APD diodes arranged in parallel, and the APD diodes correspond to the laser diodes in a one-to-one arrangement order; each APD diode is used to receive the laser emitted by the corresponding laser diode, and the laser receiving circuit is used to generate a laser receiving signal and output it to the digital processing unit; The laser driving circuit includes a single high-speed driving circuit and a laser diode control circuit corresponding to each of the laser diodes; the high-speed driving circuit is used to generate a laser diode driving signal based on the laser emission signal; the laser diode control circuit is used to control the opening and closing of the corresponding laser diode to achieve time-sharing conduction of multiple laser diodes; The laser diodes in the array laser diode are arranged at an acute angle up and down; the APD diodes in the array APD diode are arranged at the acute angle up and down; The digital processing unit is used to obtain the distance from the corresponding laser to the measured object based on the laser emission signal and the laser reception signal.

2. The TOF-based multi-beam laser ranging sensor according to claim 1, characterized in that: The digital processing unit includes an FPGA module and a TOF time-of-flight measurement circuit; the TOF time-of-flight measurement circuit is used to calculate the time difference between the laser emission signal and the laser reception signal; the FPGA module is used to generate a laser emission signal and send it to the laser emission unit, and calculate the distance between the corresponding laser and the object to be measured based on the time difference.

3. The TOF-based multi-beam laser ranging sensor according to claim 1, characterized in that: The laser receiving circuit includes an I / V circuit, a gain amplifier circuit, a constant ratio timing circuit and a digital shaping circuit; the I / V circuit is used to convert the current signal output by the APD diode into a voltage signal; the gain amplifier circuit is used to amplify the voltage signal; the constant ratio timing circuit and the digital shaping circuit are used to perform constant ratio timing and digital shaping on the amplified voltage signal, respectively.

4. The TOF-based multi-beam laser ranging sensor according to claim 1, characterized in that: The number of the laser diodes and the APD diodes is 3-16.

5. The TOF-based multi-beam laser ranging sensor according to claim 1, characterized in that: The optical system unit includes a transmitting mirror and a receiving mirror; the transmitting mirror is used to focus the laser emitted by the laser diode onto the object to be measured; the receiving mirror is used to focus the laser reflected back from the object to be measured onto the APD diode corresponding to the laser diode.

6. The TOF-based multi-beam laser ranging sensor according to claim 1, characterized in that: It also includes a system compensation unit, which is connected to the laser receiving unit and the digital processing unit, and includes a temperature compensation circuit and an APD high-voltage compensation circuit; the temperature compensation circuit is used to collect temperature information of the array APD diode and output it to the digital processing unit; the APD high-voltage compensation circuit is used to generate a DC high voltage to drive the array APD diode, and collect voltage information on the array APD diode and output it to the digital processing unit; The digital processing unit is also used to perform temperature compensation and high voltage compensation on the array APD diode based on the temperature information, and to correct the DC high voltage according to the voltage information.

7. The TOF-based multi-beam laser ranging sensor according to claim 1, characterized in that: The laser emission signal is a narrow pulse signal, and the frequency of the narrow pulse signal is evenly distributed to each laser diode as the driving frequency of the laser diode.

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