Time-to-digital converter based measurement method and system

Abstract

This application discloses a measurement method and system based on a time-to-digital converter. A signal driving module is connected to a laser diode, and its common terminal is connected to a first signal conversion module. The signal conversion module is connected to the time-to-digital converter. The time-to-digital converter is connected to a second signal conversion module. The second signal conversion module is connected to a delay circuit module, which in turn is connected to an optoelectronic device. The signal driving module drives the laser diode to emit laser pulses. The first signal conversion module converts the signal into a digital signal. The optoelectronic device converts the echo signal into an electrical signal. The delay circuit module delays the electrical signal before sending it to the second signal conversion module, which then converts the delayed electrical signal into a delayed digital signal and sends it to the time-to-digital converter. By delaying the echo signal through the delay circuit module, the difference between the driving signal and the echo signal is made greater than the minimum time interval, thereby eliminating the blind zone.

Description

Technical Field

[0001] This application relates to the field of time measurement technology, and in particular to a measurement method and system based on a time-to-digital converter. Background Technology

[0002] LiDAR is widely used in fields such as autonomous driving and robot navigation to accurately measure the distance to objects, especially when high precision is required for close-range detection.

[0003] Currently, the application of time-to-digital converters in lidar measurements typically requires a minimum time interval of 3.5 ns between the start and stop times. If this time interval is less than 3.5 ns, the echo signal will be ignored, causing the lidar to fail to obtain accurate distance information in some cases. Specifically, 3.5 ns corresponds to a distance of approximately 0.6 meters, which is a blind zone. This means that objects within the blind zone cannot be accurately measured. Summary of the Invention

[0004] This application provides a measurement method and system based on a time-to-digital converter, with the aim of eliminating blind spots.

[0005] To achieve the above objectives, this application provides the following technical solution:

[0006] The first aspect of this application provides a measurement system based on a time-to-digital converter, the measurement system comprising: a signal driving module, a laser diode LD1, a first signal conversion module, an optoelectronic device, a delay circuit module, a time-to-digital converter, and a second signal conversion module;

[0007] The output terminal of the signal driving module is connected to the cathode of the laser diode LD1, and the common terminal of the connection is connected to the input terminal of the first signal conversion module. The anode of the laser diode LD1 is grounded.

[0008] The output terminal of the first signal conversion module is connected to the first input terminal of the time-to-digital converter;

[0009] The second input terminal of the time-to-digital converter is connected to the output terminal of the second signal conversion module, the input terminal of the second signal conversion module is connected to the output terminal of the delay circuit module, and the input terminal of the delay circuit module is connected to the output terminal of the optoelectronic device.

[0010] The signal driving module drives the laser diode LD1 to generate a driving signal; the laser diode LD1 uses the driving signal as a laser pulse and emits the laser pulse; at the same time as the laser pulse is emitted, the laser diode LD1 also sends the driving signal to the first signal conversion module, the first signal conversion module converts the driving signal into a digital signal, and sends the digital signal as a start signal to the time-to-digital converter.

[0011] When the laser pulse contacts an object, it sends an echo signal. Upon receiving the echo signal, the optoelectronic device converts it into an electrical signal. The delay circuit module delays the electrical signal. The second signal conversion module converts the delayed electrical signal into a delayed digital signal and sends the delayed digital signal as a termination signal to the time-to-digital converter. The time-to-digital converter measures the distance to the object based on the start and termination signals.

[0012] Optionally, the measurement system further includes: a charging protection module;

[0013] The input terminal of the charging protection module is connected to the output terminal of the signal driving module, and its common terminal is connected to the cathode of the laser diode LD1.

[0014] The output terminal of the charging protection module is connected to the input terminal of the first signal conversion module;

[0015] During the process of the signal driving module driving the laser diode LD1 to generate a driving signal, the charging protection module protects the laser diode LD1 from reverse breakdown.

[0016] After the laser pulse is sent, the charging protection module charges the signal driving module.

[0017] Optionally, the signal driving module includes: a power supply, a microcontroller unit, a driving unit, a field-effect transistor Q1, a first resistor R1, and a first capacitor C1;

[0018] The output terminal of the microcontroller unit is connected to the input terminal of the drive unit, the output terminal of the drive unit is connected to the gate of the field-effect transistor Q1, and the source of the field-effect transistor Q1 is grounded.

[0019] The drain of the field-effect transistor Q1 is connected to one end of the first resistor R1, and the common terminal of the connection is connected to one end of the first capacitor C1. The other end of the first resistor R1 is connected to the power supply.

[0020] The other end of the first capacitor C1 is connected to the input terminal of the charging protection module, and its common terminal is connected to the cathode of the laser diode LD1.

[0021] When the output waveform of the microcontroller is low, the drive circuit outputs a low level, and the drain of the field-effect transistor Q1 is turned off; the power supply charges the first capacitor C1 through the first resistor R1 and the charging protection module.

[0022] When the output waveform of the microcontroller is high, the driving circuit outputs a high level, and the drain of the field-effect transistor Q1 is turned on; the first capacitor C1 is discharged through the field-effect transistor Q1; when the voltage difference across the capacitor is a preset voltage difference value, the laser diode LD1 is turned on and generates a driving signal.

[0023] Optionally, the power supply voltage is positively correlated with the emission power of the laser diode LD1.

[0024] Optionally, the charging protection module includes: a diode D1, a second resistor R2, a second capacitor C2, and a third resistor R3;

[0025] The anode of the diode D1 is connected to the common terminal of the output terminal of the signal driving module and the cathode of the laser diode LD1, and the common terminal is connected to one end of the second resistor R2 and one end of the second capacitor C2.

[0026] The cathode of the diode D1 is connected to the other end of the second resistor R2, and the common terminal of the connection is grounded.

[0027] The other end of the second capacitor C2 is connected to one end of the third resistor R3, and the other end of the third resistor R3 is connected to the input terminal of the first signal conversion module.

[0028] Optionally, the first signal conversion module and the second signal conversion module include comparators.

[0029] Optionally, the delay circuit module includes a register; the register is used to filter out delay paths through a preset program and perform delay processing on the electrical signal according to the delay paths.

[0030] Optionally, the optoelectronic device is specifically a photodiode or a silicon photomultiplier tube.

[0031] A second aspect of this application provides a measurement method based on a time-to-digital converter, applied to the time-to-digital converter-based measurement system described in the first aspect above, comprising:

[0032] The signal driving module drives the laser diode to generate a driving signal;

[0033] The laser diode LD1 uses the driving signal as a laser pulse and emits the laser pulse;

[0034] Simultaneously with the transmission of the laser pulse, the laser diode LD1 sends the driving signal to the first signal conversion module; the first signal conversion module converts the driving signal into a digital signal and sends the digital signal as a start signal to the time-to-digital converter.

[0035] When the laser pulse comes into contact with an object, an echo signal is fed back.

[0036] When the optoelectronic device receives the echo signal, it converts the echo signal into an electrical signal.

[0037] The delay circuit module performs delay processing on the electrical signal;

[0038] The second signal conversion module converts the delayed electrical signal into a delayed digital signal, and sends the delayed digital signal as a termination signal to the time-to-digital converter.

[0039] The time-to-digital converter measures the distance to the object based on the start and stop signals.

[0040] Optionally, the delay circuit module performs delay processing on the electrical signal, including:

[0041] The delay circuit module selects the delay path corresponding to the transmission time of the digital signal from all delay paths;

[0042] The delay circuit module performs delay processing on the electrical signal according to the delay path.

[0043] The technical solution provided in this application includes a signal driving module connected to a laser diode, with its common terminal connected to a first signal conversion module; the signal conversion module is connected to a time-to-digital converter; the time-to-digital converter is connected to a second signal conversion module; the second signal conversion module is connected to a delay circuit module, which in turn is connected to an optoelectronic device; the signal driving module drives the laser diode to emit laser pulses; the first signal conversion module converts the signal into a digital signal and sends it as a start signal to the time-to-digital converter; the optoelectronic device converts the echo signal into an electrical signal; the delay circuit module delays the electrical signal before sending it to the second signal conversion module, which then converts the delayed electrical signal into a delayed digital signal as a termination signal and sends it to the time-to-digital converter. By delaying the echo signal through the delay circuit module, the difference between the driving signal and the echo signal is made greater than the minimum time interval, thereby eliminating the blind zone. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 A schematic diagram of a first architecture of a measurement system based on a time-to-digital converter provided for an embodiment of this application;

[0046] Figure 2 A schematic diagram of temperature drift in a delay circuit module provided in an embodiment of this application;

[0047] Figure 3 A schematic diagram of a second architecture of a measurement system based on a time-to-digital converter provided for embodiments of this application;

[0048] Figure 4 A schematic diagram of a third architecture of a measurement system based on a time-to-digital converter provided for embodiments of this application;

[0049] Figure 5 A schematic diagram of the fourth architecture of a measurement system based on a time-to-digital converter provided for embodiments of this application;

[0050] Figure 6 A flowchart illustrating a measurement method based on a time-to-digital converter, provided for an embodiment of this application;

[0051] Figure 7 This is a schematic diagram of the measurement range under an extended calibration mode provided in an embodiment of this application.

[0052] Figure label:

[0053] 11-Signal drive module; LD1-Laser diode; 31-Charging protection module; 12-Signal conversion module; 13-Optoelectronic device; 14-Delay circuit module; 15-Time-to-digital converter; 16-Second signal conversion module; 41-Power supply; 42-Microcontroller unit; 43-Drive circuit; Q1-Field effect transistor; R1-First resistor; C1-First capacitor; D1-Diode; R2-Second resistor; C2-Second capacitor; R3-Third resistor. Detailed Implementation

[0054] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0055] In this application, the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0056] like Figure 1 The diagram shown is a schematic of the architecture of a measurement system based on a time-to-digital converter provided in an embodiment of this application. The measurement system includes: a signal driving module 11, a laser diode LD1, a first signal conversion module 12, an optoelectronic device 13, a delay circuit module 14, a time-to-digital converter 15, and a second signal conversion module 16.

[0057] The output terminal of the signal driving module 11 is connected to the cathode of the laser diode LD1, and its common terminal is connected to the input terminal of the first signal conversion module 12. The anode of the laser diode LD1 is grounded.

[0058] Optionally, the first signal conversion module 12 and the second signal conversion module 16 include comparators. Specifically, the first signal conversion module 12 and the second signal conversion module 16 also include peripheral devices, such as peripheral threshold levels.

[0059] The output of the first signal conversion module 12 is connected to the first input of the time-to-digital converter 15.

[0060] The second input terminal of the time-to-digital converter 15 is connected to the output terminal of the second signal conversion module 16, the input terminal of the second signal conversion module 16 is connected to the output terminal of the delay circuit module 14, and the input terminal of the delay circuit module 14 is connected to the output terminal of the optoelectronic device 13.

[0061] Furthermore, the delay circuit module 14 includes a register.

[0062] The register is used to delay electrical signals. Different delay paths can be selected through program settings, and the electrical signals are delayed according to the delay path.

[0063] Optionally, the optoelectronic device 13 is specifically a photodiode (PD), such as an avalanche photodiode (APD) or a silicon photomultiplier tube (SiPM).

[0064] The signal driving module 11 drives the laser diode LD1 to generate a driving signal; the laser diode LD1 uses the driving signal as a laser pulse and emits a laser pulse; at the same time as the laser pulse is emitted, the laser diode LD1 also sends the driving signal to the first signal conversion module 12, the first signal conversion module 12 converts the driving signal into a digital signal, and sends the digital signal as a start signal (i.e., Start signal) to the time-to-digital converter 15.

[0065] When the laser pulse comes into contact with the object, it sends back an echo signal. When the photoelectric device 13 receives the echo signal, it converts the echo signal into an electrical signal. The delay circuit module 14 delays the electrical signal. The second signal conversion module 16 converts the delayed electrical signal into a delayed digital signal and sends the delayed digital signal as a termination signal to the time-to-digital converter 15. The time-to-digital converter 15 measures the distance to the object based on the start signal and the termination signal (i.e., the STOP signal).

[0066] Understandably, comparators typically have a group delay of 2-3 ns, resulting in a certain delay between the Start signal output by the comparator and the laser output signal. To ensure that the difference between the STOP signal and the Start signal is greater than the requirement of approximately 3.5 ns, a delay design is needed on the STOP signal input channel, specifically by using delay circuit module 14 to delay the STOP signal.

[0067] Furthermore, the delay circuit module 14 is affected by temperature changes. Therefore, while meeting the minimum measurement blind zone requirement, the delay time should be as small as possible to help reduce the temperature drift of the entire system. Figure 2 As shown. While ensuring the ranging blind zone meets requirements, the delay circuit module 14 can be adjusted to the minimum delay via program settings, thereby shortening the near-range blind zone and reducing the impact of temperature drift.

[0068] Furthermore, combined with Figure 1 See the content shown. Figure 3 The measurement system also includes a charging protection module 31.

[0069] The input terminal of the charging protection module 31 is connected to the output terminal of the signal driving module 11, and its common terminal is connected to the cathode of the laser diode LD1.

[0070] The output terminal of the charging protection module 31 is connected to the input terminal of the signal conversion module 12.

[0071] In the process of the signal driving module 11 driving the laser diode LD1 to generate a driving signal, the charging protection module 31 protects the laser diode LD1 from being reverse-broken.

[0072] After sending the digital signal, the charging protection module 31 charges the signal driving module 11.

[0073] Furthermore, combined with Figure 3 See the content shown. Figure 4 The signal driving module includes: a power supply 41, a microcontroller unit 42, a driving circuit 43, a field-effect transistor Q1, a first resistor R1, and a first capacitor C1.

[0074] The output terminal of the microcontroller unit 42 is connected to the input terminal of the drive circuit 43, the output terminal of the drive circuit 43 is connected to the gate of the field-effect transistor Q1, and the source of the field-effect transistor Q1 is grounded.

[0075] Optionally, the microcontroller 42 is a microcontroller or a digital signal processor (DSP).

[0076] The drain of the field-effect transistor Q1 is connected to one end of the first resistor R1, and the common terminal of the connection is connected to one end of the first capacitor C1. The other end of the first resistor R1 is connected to the power supply 41.

[0077] Optionally, the power supply voltage is positively correlated with the emission power of the laser diode LD1.

[0078] Specifically, power supply 41 is a high-voltage power supply. The range of the high-voltage power supply can be determined according to the laser emission power of laser diode LD1, and is generally set to 20-100V.

[0079] The other end of the first capacitor C1 is connected to the input terminal of the charging protection module 31, and its common terminal is connected to the cathode of the laser diode LD1.

[0080] When the output waveform of the microcontroller unit 42 is low, the drive circuit 43 outputs a low level, and the drain of the field-effect transistor Q1 is turned off; the power supply charges the first capacitor C1 through the first resistor R1 and the charging protection module 31.

[0081] When the output waveform of the microcontroller unit 42 is high, the drive circuit outputs a high level, and the drain of the field-effect transistor Q1 is turned on; the first capacitor C1 discharges through the field-effect transistor Q1; when the voltage difference across the capacitor is a preset voltage difference (e.g., 15 or 20V), the laser diode LD1 is turned on and generates a drive signal.

[0082] It should be noted that a stable and reliable Start signal is required for measuring the laser's time of flight. Since the Start signal output by the microcontroller needs to be processed before it can activate the laser diode LD1 via the field-effect transistor Q1, temperature changes during transmission will cause additional temperature drift in these links. Typically, we sample the drive signal at the laser diode LD1 as the Start signal. However, it's important to note that the drive signal for the laser diode LD1 is an analog signal, while the time-to-digital converter 15 accepts digital signals. Therefore, the signal conversion module 12 is needed to convert the analog signal to a digital signal for processing by the time-to-digital converter 15.

[0083] Furthermore, combined with Figure 4 For the content shown, please refer to [link / reference]. Figure 5 The charging protection module includes: diode D1, second resistor R2, second capacitor C2 and third resistor R3.

[0084] The anode of diode D1 is connected to the common terminal of the output terminal of the signal driving module and the cathode of laser diode LD1. The common terminal of this connection is connected to one end of the second resistor R2 and one end of the second capacitor C2.

[0085] The cathode of diode D1 is connected to the other end of the second resistor R2, and the common terminal of the connection is grounded.

[0086] The other end of the second capacitor C2 is connected to one end of the third resistor R3, and the other end of the third resistor R3 is connected to the input terminal of the signal conversion module 12.

[0087] When the field-effect transistor Q1 turns on, the voltage on the left side of the first capacitor C1 drops rapidly to near ground (GND). Since the voltage across the first capacitor C1 cannot change instantaneously, the voltage on the right side of the first capacitor C1 remains at -U to maintain the voltage difference of the first capacitor C1 at U. At this time, the cathode of the laser diode LD1 is at -U, and the anode is at GND. Current flows instantaneously from GND to -U on the right side of the first capacitor C1. This causes a negative pulse signal to be generated at diode D1. After coupling through the second capacitor C2 and being current-limited by the third resistor R3, it is transmitted to the comparator, which outputs a positive pulse as the start signal (i.e., the Start signal) of the time-to-digital converter 15.

[0088] When the field-effect transistor Q1 is turned off, the high-voltage power supply recharges the first capacitor C1 through the first resistor R1 and the diode D1, so that the charge stored in the first capacitor C1 reaches Q=C*U. At this time, the comparator samples the emission pulse of the laser diode LD1.

[0089] As can be seen from the above, the function of diode D1 is to protect laser diode LD1 and prevent it from being broken down due to reverse voltage; at the same time, diode D1 is connected in parallel with the second resistor R2 to provide a charging circuit for the first capacitor C1.

[0090] It should be noted that when the output waveform of the microcontroller unit 42 is low, the output level of the drive circuit 43 is also low. At this time, the field-effect transistor Q1 is turned off, and the high-voltage power supply charges the first capacitor C1 through the circuit of the first resistor R1 and the diode D1. The voltage on the left side of the first capacitor C1 reaches the high-voltage voltage V1, and the right side of the first capacitor C1 is grounded through the second resistor R2. When the microcontroller unit 42 outputs a high level, the output level of the drive circuit 43 is also high. At this time, the field-effect transistor Q1 is turned on, and the high-voltage power supply discharges through the first resistor R1 and the field-effect transistor Q1. The voltage on the left side of the first capacitor C1 is instantly pulled down to 0V. Since the voltage across the capacitor cannot change abruptly, when the left side of the first capacitor C1 is 0V, the right side still maintains a voltage difference of V1. The voltage on the right side of the first capacitor C1 directly becomes -V1. At this time, the anode of the laser diode LD1 is 0V and the cathode is -V1. The laser diode LD1 emits light instantaneously and generates a drive signal.

[0091] In summary, by delaying the echo signal (i.e., the STOP signal) using a delay circuit module, the difference between the drive signal and the echo signal is made greater than the minimum time interval, thereby eliminating the blind zone.

[0092] like Figure 6 The diagram shows a flowchart of a measurement method based on a time-to-digital converter provided in this application. Applied to any of the time-to-digital converter-based measurement systems shown above, the method includes the following steps:

[0093] S601: The signal driving module drives the laser diode to generate a driving signal.

[0094] The signal driving module drives the laser diode to emit light and generates a driving signal, which is the Start signal.

[0095] S602: Laser diode LD1 uses the drive signal as a laser pulse and emits a laser pulse.

[0096] S603: While the laser pulse is being transmitted, the laser diode LD1 sends a drive signal to the first signal conversion module; the first signal conversion module converts the drive signal into a digital signal and sends the digital signal as a start signal (i.e., Start signal) to the time-to-digital converter.

[0097] Understandably, since the signal received by the time-to-digital converter is a digital signal, the drive signal needs to be converted into a digital signal by the first signal conversion module.

[0098] S604: When a laser pulse comes into contact with an object, it sends an echo signal back.

[0099] S605: When an optoelectronic device receives an echo signal, it converts the echo signal into an electrical signal.

[0100] S606: Delay circuit module performs delay processing on electrical signals.

[0101] It should be noted that there will be a time delay during the signal conversion process, which will cause the time of the digital signal input to the time-to-digital converter to be very close to that of the echo signal. Therefore, a delay circuit module is needed to delay the electrical signal so that the time interval between the digital signal and the echo signal is greater than the required measurement time interval (e.g., 3.5 ns).

[0102] Optionally, in another embodiment of this application, the specific implementation of the delay circuit module performing delay processing on the electrical signal in step S606 includes processes A1 to A2.

[0103] A1: The delay circuit module selects the delay path corresponding to the transmission time of the digital signal from all delay paths.

[0104] Specifically, the delay circuit module selects the path with the shortest delay time from all delay paths while meeting the measurement time interval requirements.

[0105] A2: The delay circuit module performs delay processing on the electrical signal according to the delay path.

[0106] Understandably, in laser ranging, the accuracy of the measurement is ensured by adjusting the delay path, ensuring that the time difference between signals is greater than the minimum interval of the system, thereby avoiding blind spots and reducing the influence of external factors (such as temperature drift).

[0107] S607: The second signal conversion module converts the delayed electrical signal into a delayed digital signal and sends the delayed digital signal as a stop signal (i.e., STOP signal) to the time-to-digital converter.

[0108] S608: Time-to-digital converter measures the distance to an object based on start and stop signals.

[0109] Specifically, calculate the time difference between the delayed digital signal and the digital signal; calculate the product of the time difference and the speed of light; divide the product by 2 to obtain the distance to the object.

[0110] Furthermore, during calibration, the measurement time is twice the reference clock time interval (i.e., 2*Tref), which limits the measurement range to this range, thus ensuring the accuracy of calibration and measurement. However, when measuring distant targets or close-range targets with strong reflections, the falling edge of the signal may exceed 2*Tref due to pulse expansion. According to existing methods, the only solution is to reduce the reference frequency to extend the measurement range. While this captures the falling edge, it also doubles the calibration time, thus doubling the measurement time.

[0111] To address this issue, the measurement range in calibration mode will be appropriately extended to handle similar situations. However, the extended measurement range will increase the difference between calibration and measurement intervals, potentially affecting accuracy. To balance this, a positioning accuracy of LSB=10ns can be used, with an overflow time range set according to actual measurement needs, thus achieving precise positioning. This approach satisfies the measurement range requirements while avoiding the increase in measurement time caused by doubling the calibration time. For details, see [link to documentation]. Figure 7 , Figure 7 In the diagram, T0 is the start time, T1 is the echo leading edge time, T2 is 2*Tref, T3 is the echo trailing edge time, T4 is the overflow time location, and T5 is the 2*Tref after frequency reduction.

[0112] In summary, by delaying the echo signal (i.e., the STOP signal) using a delay circuit module, the difference between the drive signal and the echo signal is made greater than the minimum time interval, thereby eliminating the blind zone.

[0113] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. In particular, for system or system embodiments, since they are fundamentally similar to method embodiments, the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments. The systems and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. Components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0114] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0115] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A measurement system based on a time-to-digital converter, characterized in that, The measurement system includes: a signal driving module, a laser diode LD1, a first signal conversion module, optoelectronic devices, a delay circuit module, a time-to-digital converter, and a second signal conversion module; The output terminal of the signal driving module is connected to the cathode of the laser diode LD1, and the common terminal of the connection is connected to the input terminal of the first signal conversion module. The anode of the laser diode LD1 is grounded. The output terminal of the first signal conversion module is connected to the first input terminal of the time-to-digital converter; The second input terminal of the time-to-digital converter is connected to the output terminal of the second signal conversion module, the input terminal of the second signal conversion module is connected to the output terminal of the delay circuit module, and the input terminal of the delay circuit module is connected to the output terminal of the optoelectronic device. The signal driving module drives the laser diode LD1 to generate a driving signal; the laser diode LD1 uses the driving signal as a laser pulse and emits the laser pulse; at the same time as the laser pulse is emitted, the laser diode LD1 also sends the driving signal to the first signal conversion module, the first signal conversion module converts the driving signal into a digital signal, and sends the digital signal as a start signal to the time-to-digital converter. When the laser pulse contacts an object, it sends an echo signal. Upon receiving the echo signal, the optoelectronic device converts it into an electrical signal. The delay circuit module delays the electrical signal. The second signal conversion module converts the delayed electrical signal into a delayed digital signal and sends the delayed digital signal as a termination signal to the time-to-digital converter. The time-to-digital converter measures the distance to the object based on the start and termination signals.

2. The system according to claim 1, characterized in that, The measurement system also includes: a charging protection module; The input terminal of the charging protection module is connected to the output terminal of the signal driving module, and its common terminal is connected to the cathode of the laser diode LD1. The output terminal of the charging protection module is connected to the input terminal of the first signal conversion module; During the process of the signal driving module driving the laser diode LD1 to generate a driving signal, the charging protection module protects the laser diode LD1 from reverse breakdown. After the laser pulse is sent, the charging protection module charges the signal driving module.

3. The system according to claim 2, characterized in that, The signal driving module includes: a power supply, a microcontroller unit, a driving unit, a field-effect transistor Q1, a first resistor R1, and a first capacitor C1; The output terminal of the microcontroller unit is connected to the input terminal of the drive unit, the output terminal of the drive unit is connected to the gate of the field-effect transistor Q1, and the source of the field-effect transistor Q1 is grounded. The drain of the field-effect transistor Q1 is connected to one end of the first resistor R1, and the common terminal of the connection is connected to one end of the first capacitor C1. The other end of the first resistor R1 is connected to the power supply. The other end of the first capacitor C1 is connected to the input terminal of the charging protection module, and its common terminal is connected to the cathode of the laser diode LD1. When the output waveform of the microcontroller is low, the drive circuit outputs a low level, and the drain of the field-effect transistor Q1 is turned off; the power supply charges the first capacitor C1 through the first resistor R1 and the charging protection module. When the output waveform of the microcontroller is high, the driving circuit outputs a high level, and the drain of the field-effect transistor Q1 is turned on; the first capacitor C1 is discharged through the field-effect transistor Q1; when the voltage difference across the capacitor is a preset voltage difference value, the laser diode LD1 is turned on and generates a driving signal.

4. The system according to claim 3, characterized in that, The power supply voltage is positively correlated with the emission power of the laser diode LD1.

5. The system according to claim 2, characterized in that, The charging protection module includes: a diode D1, a second resistor R2, a second capacitor C2, and a third resistor R3; The anode of the diode D1 is connected to the common terminal of the output terminal of the signal driving module and the cathode of the laser diode LD1, and the common terminal is connected to one end of the second resistor R2 and one end of the second capacitor C2. The cathode of the diode D1 is connected to the other end of the second resistor R2, and the common terminal of the connection is grounded. The other end of the second capacitor C2 is connected to one end of the third resistor R3, and the other end of the third resistor R3 is connected to the input terminal of the first signal conversion module.

6. The system according to claim 1, characterized in that, The first signal conversion module and the second signal conversion module include comparators.

7. The system according to claim 1, characterized in that, The delay circuit module includes a register; the register is used to filter out delay paths through a preset program and to delay the electrical signal according to the delay paths.

8. The system according to claim 1, characterized in that, The optoelectronic device is specifically a photodiode or a silicon photomultiplier tube.

9. A measurement method based on a time-to-digital converter, characterized in that, The measurement system based on a time-to-digital converter, applicable to any one of claims 1 to 8, comprises: The signal driving module drives the laser diode to generate a driving signal; The laser diode LD1 uses the driving signal as a laser pulse and emits the laser pulse; Simultaneously with the transmission of the laser pulse, the laser diode LD1 also sends the driving signal to the first signal conversion module; the first signal conversion module converts the driving signal into a digital signal and sends the digital signal as a start signal to the time-to-digital converter. When the laser pulse comes into contact with an object, an echo signal is fed back. When the optoelectronic device receives the echo signal, it converts the echo signal into an electrical signal. The delay circuit module performs delay processing on the electrical signal; The second signal conversion module converts the delayed electrical signal into a delayed digital signal, and sends the delayed digital signal as a termination signal to the time-to-digital converter. The time-to-digital converter measures the distance to the object based on the start and stop signals.

10. The method according to claim 9, characterized in that, The delay circuit module performs delay processing on the electrical signal, including: The delay circuit module selects the delay path corresponding to the transmission time of the digital signal from all delay paths; The delay circuit module performs delay processing on the electrical signal according to the delay path.

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