WO2020113360A1

WO2020113360A1 - Sampling circuit, sampling method, ranging apparatus and mobile platform

Info

Publication number: WO2020113360A1
Application number: PCT/CN2018/118876
Authority: WO
Inventors: 黄森洪; 梅雄泽; 刘祥; 洪小平
Original assignee: 深圳市大疆创新科技有限公司
Priority date: 2018-12-03
Filing date: 2018-12-03
Publication date: 2020-06-11
Also published as: CN111527419A

Abstract

A sampling circuit (130), a sampling method, a ranging apparatus (200) and a mobile platform. The sampling circuit (130) comprises: a time-to-digital conversion module and an analog-digital conversion module, which are arranged in parallel, and the sampling circuit (130) further comprises a control module, wherein the time-to-digital conversion module is used for receiving an electrical signal converted from an optical pulse signal and performing a comparison operation on the electrical signal and a preset threshold value, and collecting time information corresponding to the electrical signal; the analog-digital conversion module is used for receiving the electrical signal converted from the optical pulse signal, and collecting, within a sampling clock frequency, an amplitude of the electrical signal corresponding to the collection time; and the control module is used for selecting the signal collected by the time-to-digital conversion module and/or the analog-digital conversion module and performing calculation, so as to obtain a parameter value of the optical pulse signal.

Description

Sampling circuit, adopting method, distance measuring device and mobile platform

Technical field

The invention relates to the technical field of laser radar, in particular to a sampling circuit, an adopting method, a distance measuring device, and a mobile platform.

Background technique

Lidar is a radar system that emits laser beams to detect the target's position, speed and other characteristic quantities. The light sensor of the lidar can convert the acquired light pulse signal into an electrical signal, and obtain the time information corresponding to the electrical signal based on the comparator, thereby obtaining the distance information between the lidar and the target.

However, in laser ranging and other products related to laser ranging, it is usually necessary to extract a variety of pulse information such as energy, arrival time, shape parameters, etc., in order to more comprehensively and accurately reflect the object information of the detected scene. Sampling and processing of pulse signals are usually bottleneck technologies related to system performance.

Therefore, it is necessary to further improve the current device and method for acquiring pulse information.

Summary of the invention

A first aspect of the present invention provides a sampling circuit, including: a time-to-digital conversion module and an analog-to-digital conversion module set in parallel, and the sampling circuit further includes a control module;

Wherein, the time-to-digital conversion module is used to receive the electrical signal converted from the optical pulse signal and compare the electrical signal with a preset threshold to collect time information corresponding to the electrical signal;

The analog-to-digital conversion module is used to receive the electrical signal converted from the optical pulse signal and collect the amplitude of the electrical signal corresponding to the acquisition time within the sampling clock frequency;

The control module is configured to select and calculate signals collected by the time-to-digital conversion module and/or the analog-to-digital conversion module to obtain parameter values of the optical pulse signal.

Optionally, the time-to-digital conversion module includes a plurality of channels, where each of the channels includes a comparator and a time-to-digital converter, wherein the first input terminal of the comparator is used to receive the conversion from the optical pulse signal For the obtained electrical signal, the second input terminal of the comparator is used to receive the preset threshold of the comparator, the output terminal of the comparator is used to output the result of the comparison operation, the time-to-digital converter and the The output terminal of the comparator is electrically connected to extract the time information corresponding to the electrical signal according to the result of the comparison operation output by the comparator;

Wherein, the preset thresholds of the comparators in the different channels are different.

Optionally, the analog-to-digital conversion module includes at least one analog-to-digital converter for collecting the amplitude of the electrical signal corresponding to the collection time.

Optionally, the control module is used to calculate the selected signal by fitting to restore the pattern of the optical pulse signal;

Or the control module is used to calculate the selected signal by using explicit statistics to obtain the parameter value of the optical pulse signal.

Optionally, the control module collects at least part of the signal of the time-to-digital conversion module and at least part of the signal collected by the analog-to-digital conversion module to perform the fitting.

Optionally, the control module is further configured to convert the sampling of the time-to-digital conversion module into the sampling of the analog-to-digital conversion module;

Or the control module is also used to convert the samples of the analog-to-digital conversion module into the samples of the time-to-digital conversion module.

Optionally, the control module is used to first calculate the sampled signal of the analog-to-digital conversion module by fitting to obtain a graph of the optical pulse signal, and then on the graph of the optical pulse signal Calibrate preset thresholds and corresponding time information.

Optionally, when the control module selects the signal:

When the width of the optical pulse signal is less than the set value of the pulse width, the signal collected by the time-to-digital conversion module is selected; and/or

When the pulse height of the optical pulse signal is less than the set value of the pulse height, the signal collected by the analog-to-digital conversion module is selected; and/or

When the width of the optical pulse signal is greater than the set value of the pulse width and the pulse height of the optical pulse signal is greater than the set value of the pulse height, if the information on the arrival time and pulse width of the optical pulse signal is required to have higher accuracy At this time, at least the signal collected by the time-to-digital conversion module is selected; if higher precision is required for the pulse energy and amplitude information of the optical pulse signal, at least the signal collected by the analog-to-digital conversion module is selected.

Optionally, the parameter value includes at least one of pulse arrival time, pulse width, pulse energy, and amplitude.

The invention also provides a sampling method based on a sampling circuit, including:

Receiving an electrical signal converted from an optical pulse signal through a time-to-digital conversion module and comparing the electrical signal with a preset threshold to collect time information corresponding to the electrical signal;

Receive the electrical signal converted from the optical pulse signal through the analog-to-digital conversion module, and collect the amplitude signal of the electrical signal corresponding to the acquisition time within the sampling clock frequency;

The signals collected by the time-to-digital conversion module and/or the analog-to-digital conversion module are selected and calculated to obtain the parameter value of the optical pulse signal.

Optionally, the time-to-digital conversion module includes multiple channels, and the multiple channels receive the electrical signal in parallel and perform a comparison operation on the electrical signal to collect time information corresponding to the electrical signal.

Optionally, different preset thresholds are respectively set for the multiple channels to receive the electrical signals in parallel and perform comparison operations on the electrical signals.

Optionally, the step of selecting and calculating the signal to obtain the parameter value of the optical pulse signal includes:

Calculate the selected signal by fitting to restore the pattern of the optical pulse signal;

Or, the explicit signal is used to calculate the selected signal to obtain the parameter value of the optical pulse signal.

Optionally, at least a part of the signals of the time-to-digital conversion module and a part of the signals collected by the analog-to-digital conversion module are selected for the fitting.

Optionally, after the signals collected by the time-to-digital conversion module and the analog-to-digital conversion module are selected, before calculation, the method further includes:

Converting the samples of the time-to-digital conversion module into the samples of the analog-to-digital conversion module;

Optionally, the sampled signal of the analog-to-digital conversion module is first calculated by fitting to obtain a graph of the optical pulse signal, and then a preset threshold is calibrated on the graph structure of the optical pulse signal and Corresponding time information.

Optionally, when selecting the signal,

Optionally, the parameter value includes at least one of pulse arrival time, pulse width, pulse energy, and pulse amplitude.

The invention also provides a distance measuring device, including:

Light emitting circuit, used to emit light pulse signal;

An optical receiving circuit, configured to receive at least part of the optical signal reflected by the optical pulse signal emitted by the optical transmitting circuit through the object, and convert the received laser signal into an electrical signal;

The above sampling circuit is used for sampling the electrical signal from the laser receiving circuit to obtain a sampling result;

The arithmetic circuit is used for calculating the distance between the object and the distance measuring device according to the sampling result.

The invention also provides a mobile platform, including:

The above distance measuring device; and

A platform body, and the light emitting circuit of the distance measuring device is installed on the platform body.

Optionally, the mobile platform includes at least one of an unmanned aerial vehicle, a car, and a robot.

The present invention provides the above sampling circuit, method, distance measuring device, and mobile platform. The sampling circuit is provided with a time-to-digital conversion module and an analog-to-digital conversion module in parallel. Sampling is performed by the above two methods, and there are more sampling points. The degree of shape reduction is better, which provides a better basis for the extraction of pulse information. In addition, the sampling circuit and the method of the present invention combine the advantages of the two types of sampling to achieve the effect of complementary advantages. On the one hand, it can take into account various information such as energy and time. For example, it can obtain higher energy accuracy while ensuring time accuracy. At the same time, it can take advantage of the advantages of the analog-to-digital conversion module for energy collection and the advantages of the time-to-digital conversion module for time collection; On the other hand, the pulse shape requirements can be widened. For example, low-amplitude wide pulses that cannot be processed by the time-to-digital conversion module can be processed by the analog-to-digital conversion module, and narrow pulses that cannot be processed by the analog-to-digital conversion module can be adopted by the time-to-digital conversion module deal with. Pulses with appropriate amplitude and pulse width can obtain better results than any solution of the analog-to-digital conversion module and the time-to-digital conversion module. For such pulses, both the analog-to-digital conversion module and the time-to-digital conversion module can contribute more sampling points, and the combined use of the two can improve the accuracy of pulse information extraction.

BRIEF DESCRIPTION

In order to more clearly explain the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, without paying any creative work, other drawings can be obtained based on these drawings.

1 is a schematic structural diagram of a sampling signal obtained by a time-to-digital conversion method according to an embodiment of the present invention;

2 is a schematic structural diagram of a sampling signal obtained by an analog-to-digital conversion method in an embodiment of the present invention;

3 is a schematic structural diagram of a sampling circuit in an embodiment of the invention;

4 is a schematic frame diagram of a distance measuring device according to an embodiment of the present invention;

5 is a schematic diagram of an embodiment of a distance measuring device provided by an embodiment of the present invention using a coaxial optical path.

detailed description

The technical solutions in the embodiments of the present invention will be described clearly and completely in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without making creative efforts fall within the protection scope of the present invention.

In laser ranging and other products related to laser ranging, it is usually necessary to extract various pulse information such as energy, arrival time, shape parameters, etc. At present, the methods of digitizing optical pulses mainly include time-to-digital conversion methods (for example, using a time-to-digital converter Time-to-Digital Converter (TDC) and analog-to-digital conversion methods (for example, using an analog-to-digital converter, Analog-to-Digital Converter, ADC).

Among them, TDC and ADC have their own advantages and disadvantages, and it is usually difficult to take into account the accuracy of extracting a variety of information. TDC can only achieve parallel acquisition of N channels, then at most N+1 amplitude values can be collected, and its sampling accuracy and discrimination in voltage amplitude are low, especially for the amplitude sampling of pulse signals is missing . In addition, near the baseline, due to the influence of baseline noise, the current TDC scheme cannot measure continuously multiple times. If the threshold is too low, after the TDC is triggered by noise, once the real pulse signal is encountered, it can no longer respond to the real pulse signal .

For ADC, the sampling rate is very high (or the sampling interval is very small). The available ADC sampling rate is generally in the GHz range, that is, a point is taken every 1 ns. In the pulse signal of about 10ns, only about 10 points can be collected, which is not enough for the acquisition of pulse information. In addition, the ADC sampling time is random with respect to the pulse signal, that is, the position of the sampling point relative to the arrival time for pulses arriving at different times is not fixed, and in actual applications, accurate pulse time information can be obtained to obtain accurate The measurement distance of the sample is worse than the random sampling method of pulse time.

In particular, on the faster pulse signal edges, the number of points collected by the ADC is limited. The faster the pulse signal edges, the fewer the collection points and the worse the recovery of the pulse signal. In the TDC scheme, regardless of the signal You can collect the points that can be triggered as fast as possible.

In laser ranging applications, the pulse signal received by the detector varies with the distance, reflectivity, diffuse reflection path, etc. of the measured object, and the amplitude and pulse width of the optical pulse will change to varying degrees. Therefore, the digital circuit and The processing method needs to adapt to pulse signals with different pulse widths and different amplitudes that change within a wide range, which puts forward higher requirements on the current TDC scheme or ADC scheme.

In order to solve the above problems, the present invention provides a sampling circuit, in which the time-to-digital conversion module and the analog-to-digital conversion module are provided in parallel in the adoption circuit, and the sampling method is provided in the adoption circuit in parallel, thereby realizing two The advantages of the method are complementary to obtain the parameter value of the optical pulse signal. Wherein, the parameter value includes but is not limited to the following information: pulse arrival time, pulse width, pulse energy and amplitude, etc.

As shown in FIG. 3, in one embodiment of the present invention, two sampling methods of ADC and TDC are integrated, including a single channel ADC module and N channel TDC modules. Among them, the sampling rate of the ADC module is f, and the number of quantization bits is M bits; and the TDC of each channel includes a comparator, and each channel sets different thresholds according to requirements to obtain the rising and falling time of the pulse at different amplitudes .

Wherein, in the time-to-digital conversion module, a multi-channel design is usually adopted, each channel is set with a different amplitude threshold, and the rising time and falling time of the pulse at the corresponding value are intercepted. TDC is a given threshold acquisition time. Only when the pulse arrives and reaches the threshold will the TDC sampling be triggered, which can achieve high-precision time measurement at the picosecond level.

As shown in FIG. 1, the time-to-digital conversion module includes multiple channels, for example, including 1 to N channels, where N is a natural number greater than 2. In addition, the preset thresholds of the comparators in the different channels are different, for example, a threshold 1 to a threshold N are set.

Each of the channels includes a comparator and a time-to-digital converter TDC. In each channel, the first input end of the comparator is used to receive an electrical signal converted from an optical pulse signal. The comparator The second input terminal is used to receive the preset threshold of the comparator, the output terminal of the comparator is used to output the result of the comparison operation, and the time-to-digital converter TDC is electrically connected to the output terminal of the comparator, Used to extract time information corresponding to the electrical signal according to the result of the comparison operation output by the comparator

In an example of the present invention, as shown in FIG. 1, the preset thresholds set in different channels are threshold 1, threshold 2 up to threshold N, and the electrical signal input to the first input terminal of the comparator includes an electrical pulse signal. The preset threshold value is threshold value 1 and when the intensity of the electrical pulse signal exceeds threshold value 1, the electrical pulse signal triggers the comparator to output a high-level signal to obtain time information corresponding to triggering threshold value 1.

Wherein, as shown in FIG. 1, the principle of a time extraction method provided by an embodiment of the present invention is: an electrical signal input to a comparator is compared with a threshold value N to obtain a first square wave signal shown by a dotted line, the first The time TN of the transition edge of the square wave signal can be regarded as the time when the electrical signal traverses the comparator. Similarly, the electrical signal input to the comparison circuit is compared with the preset threshold value 1 to obtain a second square wave signal as shown by the dotted line. The time T1 of the transition edge of the second square wave signal can be regarded as the electrical signal passing through the comparator Time. The method of acquiring the time signal is the same for other channels.

Among them, the TDC scheme has a very high time resolution ability (tens of ps level), especially in the relatively fast pulse signal edge acquisition has sufficient advantages, and contributes more to the accurate collection of pulse signal time. Therefore, when there are many samples with moderate pulse height and width, the TDC scheme can be used to obtain higher-precision information such as arrival time and pulse width information.

Among them, the advantage of the ADC method is that it has higher voltage acquisition accuracy, and may have more contributions in the amplitude and energy of the pulse. The sampling method of the ADC module is shown in Figure 2. The sampling clock frequency is f, so every interval t = 1/f, there is a sample value of amplitude. If there is a sufficiently high sampling rate, the digital signal of the ADC can restore the time course of the amplitude of the optical pulse signal. If the amplitude information is quantized into M bits, the energy accuracy can reach 1/2M, and the amplitude information of the optical pulse can be accurately measured. In an example of the present invention, the sampling rate of the ADC is 1-10 GHz, for example, a point is taken every 1 ns.

Exemplarily, sampling at time t will obtain the first amplitude signal, sampling at time 2t will obtain the second amplitude information, and so on, and sampling at Kt time will obtain the first K amplitude signal to obtain the amplitude of the electrical signal corresponding to the acquisition time.

In the embodiment of the present invention, the above two methods are used together, that is, it can have sufficient advantages for fast pulse signal edge acquisition and can also ensure a higher voltage acquisition accuracy. In the pulse amplitude, energy In terms of accessibility.

As shown in FIG. 3, in an example of the present invention, the ADC module and the N-channel TDC module run in parallel to generate digital sample data of A1, B1, B2, ...BN, and transmit them to the control module for processing in parallel. The module is used to select and calculate the signal collected by the time-to-digital conversion module and/or the analog-to-digital conversion module to obtain the parameter value of the optical pulse signal.

Optionally, in an example of the present invention, the control module uses a Micro Controller Unit (MCU) to process data.

Optionally, the method for the control module to select the signals collected by the time-to-digital conversion module and/or the analog-to-digital conversion module may include any one of the following solutions or a combination of any at least two solutions:

First, choose by category and make full use of the advantages of each module for processing. such as:

1. When the width of the optical pulse signal is smaller than the set value of the pulse width, use the TDC scheme to extract the pulse information and extract the signal collected by the time-to-digital conversion module. Wherein, the pulse width setting value is used to characterize the extent to which the width of the optical pulse signal can be used to extract pulse information using the TDC scheme, and its specific value can be selected according to actual needs, and is not limited to a certain value range. Using the TDC method can avoid the insufficient sampling of the ADC due to the small pulse width.

2. When the pulse height of the optical pulse signal is less than the set value of the pulse height, the ADC scheme is used to extract pulse information, wherein the set value of the pulse height is used to characterize the extent to which the height of the optical pulse signal can be Using the ADC scheme to extract pulse information, the specific value can be selected according to actual needs, and is not limited to a certain value range. Using the ADC method can avoid the situation where the TDC is insufficiently sampled because the pulse height is too small.

3. When the width of the optical pulse signal is greater than the set value of the pulse width and the pulse height of the optical pulse signal is greater than the set value of the pulse height, at least one of the ADC method and the TDC method may be selected, or Use two schemes for sampling at the same time. That is, when there are many samples with moderate pulse height and width, the TDC scheme can be used to obtain higher precision information for TDC schemes such as arrival time and pulse width information, and the higher precision information can be used for ADC schemes such as pulse energy/amplitude. ADC solution.

Of course, it can also be selected according to the required parameters and precision of the optical pulse signal. For example, if higher precision is required for the arrival time and pulse width information of the optical pulse signal, at least the signal collected by the time-to-digital conversion module is selected; When the pulse energy and amplitude information of the optical pulse signal require higher accuracy, at least the signal collected by the analog-to-digital conversion module is selected. Of course, it is also possible to select two signals obtained by the module at the same time.

After obtaining the signal collected by the time-to-digital conversion module and/or the analog-to-digital conversion module, the control module is used to calculate the selected signal. The calculation method includes any one of the following schemes or two Combination of options:

I. Calculate the selected signal using a fitting method, where the fitting method is to mark the acquired pulse signal at a corresponding position in the pattern of the optical pulse signal, and then restore the pulse pattern of the optical pulse signal After obtaining the pulse pattern of the pulse signal, the required information such as at least one of pulse arrival time, pulse width, pulse energy and amplitude can be further read on the pulse pattern.

II. The control module calculates the selected signal by using explicit statistics. In this calculation method, each selected sampling point is calculated correspondingly to obtain the corresponding value at each sampling point. The parameter values of the optical pulse signal are used to obtain numerous point values.

It should be noted that the above two methods for the control module to calculate the selected signal are also applicable to any combination of the following two processing methods or other processing methods. Without special instructions, fitting processing and explicit The methods of statistics are all explained above.

Second, direct deep fusion processing. In the method, the sampling points of the two types of sampling modules are fitted together to obtain the pulse pattern of the pulse signal. Of course, certain sampling points can also be extracted separately for fitting, for example, sampling points with rising edges are selected for fitting. According to the fitting result, the pulse arrival time, pulse width, pulse energy, etc. are extracted. The two types of sampling together can provide more sampling points than either method, so the accuracy of the fitting can be improved, thereby improving the accuracy of the extraction of pulse information.

Third, deep fusion after conversion. Conversion refers to the conversion of one of the adopted results into the adoption of another method, which is then processed, including:

1. Convert the sampling result of ADC to TDC sampling, or/and convert the sampling result of TDC to ADC sampling. Then put the conversion result with another sampled point, and use a certain way to extract the pulse information. For example, at least one of fitting processing and explicit statistics.

In the example of the present invention, if the ADC sampling is converted to TDC sampling, the TDC scheme method is used for information extraction; otherwise, if the TDC sampling is converted to ADC sampling, the ADC scheme method is used. Information extraction. The statistics used during extraction should include two types of sampling: TDC sampling + ADC conversion sampling, or ADC sampling + TDC conversion sampling.

2. For the conversion between ADC and TDC sampling, the method of first fitting/interpolation and then sampling can be used. In the example of the present invention, for example, the sampling of the ADC is firstly fitted in a fitting manner to obtain a graph of the optical pulse signal, and after fitting, a threshold is given in a manner of simulating TDC to acquire time.

The present invention provides a sampling circuit in which a time-to-digital conversion module and an analog-to-digital conversion module are provided in parallel, sampling is performed by the above two methods, there are more sampling points, and the degree of restoration of the pulse shape is better, which is a pulse Information extraction provides a better basis. In addition, the sampling circuit and the method in the present invention combine the advantages of the two types of sampling to achieve the effect of complementary advantages. On the one hand, it can take into account various information such as energy and time. For example, it can obtain higher energy accuracy while ensuring time accuracy. At the same time, it can take advantage of the advantages of the analog-to-digital conversion module for energy collection and the advantages of the time-to-digital conversion module for time collection; On the other hand, the pulse shape requirements can be widened. For example, low-amplitude wide pulses that cannot be processed by the time-to-digital conversion module can be processed by the analog-to-digital conversion module, and narrow pulses that cannot be processed by the analog-to-digital conversion module can be adopted by the time-to-digital conversion module. deal with. Pulses with appropriate amplitude and pulse width can obtain better results than any solution of the analog-to-digital conversion module and the time-to-digital conversion module. For such pulses, both the analog-to-digital conversion module and the time-to-digital conversion module can contribute more sampling points, and the combined use of the two can improve the accuracy of pulse information extraction.

In another embodiment of the present invention, a sampling method based on a sampling circuit is provided, including:

The time-to-digital conversion module and the analog-to-digital conversion module are set in parallel in the adopting circuit, and the sampling method is set in parallel in the adopting circuit, so as to realize the complementary advantages of the two adopting methods to obtain the optical pulse signal The parameter value. Wherein, the parameter value includes but is not limited to the following information: pulse arrival time, pulse width, pulse energy and amplitude, etc.

As shown in FIG. 3, in an embodiment of the present invention, two sampling methods of ADC and TDC are integrated. Among them, the sampling rate of the ADC sampling method is f, and the number of quantization bits is M bits; and the TDC of each channel includes a comparator, and each channel sets different thresholds according to requirements to obtain the rising edge time and falling time of pulses with different amplitudes Along time.

Each of the channels includes a comparator and a time-to-digital converter TDC. In an example of the present invention, as shown in FIG. 1, the preset thresholds set in different channels are threshold 1, threshold 2 up to threshold N, and the electrical signal input to the first input terminal of the comparator includes an electrical pulse signal. The preset threshold value is threshold value 1 and when the intensity of the electrical pulse signal exceeds threshold value 1, the electrical pulse signal triggers the comparator to output a high-level signal to obtain time information corresponding to triggering threshold value 1.

3. When the width of the optical pulse signal is greater than the set value of the pulse width and the pulse height of the optical pulse signal is greater than the set value of the pulse height, at least one of the ADC method and the TDC method may be selected, or Sampling is performed using both schemes. That is, when there are many samples with moderate pulse height and width, the TDC scheme can be used to obtain higher precision information for TDC schemes such as arrival time and pulse width information, and the higher precision information can be used for ADC schemes such as pulse energy/amplitude. ADC solution.

The sampling circuits provided by various embodiments of the present invention may be applied to a distance measuring device, and the distance measuring device may be an electronic device such as a laser radar or a laser distance measuring device. In one embodiment, the distance measuring device is used to sense external environment information, for example, distance information, azimuth information, reflection intensity information, speed information, etc. of the environmental target. In an implementation manner, the distance measuring device can detect the distance between the detecting object and the distance measuring device by measuring the time of light propagation between the distance measuring device and the detection object, that is, Time-of-Flight (TOF). Alternatively, the distance measuring device may also detect the distance between the detected object and the distance measuring device through other techniques, such as a distance measuring method based on phase shift measurement, or a distance measuring method based on frequency shift measurement. There are no restrictions.

For ease of understanding, the following describes the working process of distance measurement in conjunction with the distance measurement device 100 shown in FIG. 4.

As shown in FIG. 4, the distance measuring device 100 may include a transmitting circuit 110, a receiving circuit 120, a sampling circuit 130 and an arithmetic circuit 140.

The transmission circuit 110 may transmit a sequence of light pulses (for example, a sequence of laser pulses). The receiving circuit 120 can receive the optical pulse sequence reflected by the detected object, and photoelectrically convert the optical pulse sequence to obtain an electrical signal, which can be output to the sampling circuit 130 after processing the electrical signal. The sampling circuit 130 may sample the electrical signal to obtain the sampling result. The arithmetic circuit 140 may determine the distance between the distance measuring device 100 and the detected object based on the sampling result of the sampling circuit 130.

Optionally, the distance measuring apparatus 100 may further include a control circuit 150, which may control other circuits, for example, may control the working time of each circuit and/or set parameters for each circuit.

It should be understood that although the distance measuring device shown in FIG. 4 includes a transmitting circuit, a receiving circuit, a sampling circuit, and an arithmetic circuit for emitting a beam of light for detection, the embodiments of the present application are not limited thereto, and the transmitting circuit , The number of any one of the receiving circuit, the sampling circuit, and the arithmetic circuit may also be at least two, for emitting at least two light beams in the same direction or respectively in different directions; wherein, the at least two light paths may be simultaneously The shot may be shot at different times. In one example, the light-emitting chips in the at least two emission circuits are packaged in the same module. For example, each emitting circuit includes a laser emitting chip, and the die in the laser emitting chips in the at least two emitting circuits are packaged together and accommodated in the same packaging space.

In some implementations, in addition to the circuit shown in FIG. 4, the distance measuring device 100 may further include a scanning module for changing at least one laser pulse sequence emitted by the transmitting circuit to change the propagation direction.

Among them, the module including the transmitting circuit 110, the receiving circuit 120, the sampling circuit 130, and the arithmetic circuit 140, or the module including the transmitting circuit 110, the receiving circuit 120, the sampling circuit 130, the arithmetic circuit 140, and the control circuit 150 may be referred to as measurement Distance module, the distance measuring module may be independent of other modules, for example, a scanning module.

A coaxial optical path may be used in the distance measuring device, that is, the light beam emitted by the distance measuring device and the reflected light beam share at least part of the optical path in the distance measuring device. For example, after at least one laser pulse sequence emitted by the transmitting circuit is emitted through the scanning module to change the propagation direction, the laser pulse sequence reflected by the detection object passes through the scanning module and enters the receiving circuit. Alternatively, the distance measuring device may also adopt an off-axis optical path, that is, the light beam emitted by the distance measuring device and the reflected light beam are respectively transmitted along different optical paths in the distance measuring device. FIG. 5 shows a schematic diagram of an embodiment of the distance measuring device of the present invention using a coaxial optical path.

The distance measuring device 200 includes a distance measuring module 210. The distance measuring module 210 includes a transmitter 203 (which may include the above-mentioned transmitting circuit), a collimating element 204, and a detector 205 (which may include the above-mentioned receiving circuit, sampling circuit, and arithmetic circuit) and Optical path changing element 206. The ranging module 210 is used to emit a light beam, and receive back light, and convert the back light into an electrical signal. Among them, the transmitter 203 may be used to transmit a light pulse sequence. In one embodiment, the transmitter 203 may emit a sequence of laser pulses. Optionally, the laser beam emitted by the transmitter 203 is a narrow-bandwidth beam with a wavelength outside the visible light range. The collimating element 204 is disposed on the exit optical path of the emitter, and is used to collimate the light beam emitted from the emitter 203, and collimate the light beam emitted from the emitter 203 into parallel light to the scanning module. The collimating element is also used to converge at least a part of the return light reflected by the detection object. The collimating element 204 may be a collimating lens or other element capable of collimating the light beam.

In the embodiment shown in FIG. 5, the optical path changing element 206 is used to combine the transmitting optical path and the receiving optical path in the distance measuring device before the collimating element 204, so that the transmitting optical path and the receiving optical path can share the same collimating element, so that the optical path More compact. In some other implementation manners, the transmitter 203 and the detector 205 may respectively use respective collimating elements, and the optical path changing element 206 is disposed on the optical path behind the collimating element.

In the embodiment shown in FIG. 5, since the beam aperture of the light beam emitted by the transmitter 203 is small and the beam aperture of the return light received by the distance measuring device is large, the light path changing element can use a small-area mirror to change The transmitting optical path and the receiving optical path are combined. In some other implementations, the light path changing element may also use a reflector with a through hole, where the through hole is used to transmit the outgoing light of the emitter 203, and the reflector is used to reflect the return light to the detector 205. This can reduce the blocking of the return light by the support of the small mirror in the case of using the small mirror.

In the embodiment shown in FIG. 5, the optical path changing element is offset from the optical axis of the collimating element 204. In some other implementations, the optical path changing element may also be located on the optical axis of the collimating element 204.

The distance measuring device 200 further includes a scanning module 202. The scanning module 202 is placed on the exit optical path of the distance measuring module 210. The scanning module 202 is used to change the transmission direction of the collimated light beam 219 emitted through the collimating element 204 and project it to the external environment, and project the return light to the collimating element 204 . The returned light is converged on the detector 205 via the collimating element 204.

In one embodiment, the scanning module 202 may include at least one optical element for changing the propagation path of the light beam, wherein the optical element may change the propagation path of the light beam by reflecting, refracting, diffracting, etc. the light beam. For example, the scanning module 202 includes a lens, a mirror, a prism, a galvanometer, a grating, a liquid crystal, an optical phased array (Optical Phased Array), or any combination of the above optical elements. In one example, at least part of the optical element is moving, for example, the at least part of the optical element is driven to move by a driving module, and the moving optical element can reflect, refract, or diffract the light beam to different directions at different times. In some embodiments, multiple optical elements of the scanning module 202 may rotate or vibrate about a common axis 209, and each rotating or vibrating optical element is used to continuously change the direction of propagation of the incident light beam. In one embodiment, the multiple optical elements of the scanning module 202 may rotate at different rotation speeds, or vibrate at different speeds. In another embodiment, at least part of the optical elements of the scanning module 202 can rotate at substantially the same rotational speed. In some embodiments, the multiple optical elements of the scanning module may also rotate around different axes. In some embodiments, the multiple optical elements of the scanning module may also rotate in the same direction, or rotate in different directions; or vibrate in the same direction, or vibrate in different directions, which is not limited herein.

In one embodiment, the scanning module 202 includes a first optical element 214 and a driver 216 connected to the first optical element 214. The driver 216 is used to drive the first optical element 214 to rotate about a rotation axis 209 to change the first optical element 214 The direction of the collimated light beam 219. The first optical element 214 projects the collimated light beam 219 to different directions. In one embodiment, the angle between the direction of the collimated light beam 219 changed by the first optical element and the rotation axis 109 changes as the first optical element 214 rotates. In one embodiment, the first optical element 214 includes a pair of opposed non-parallel surfaces through which the collimated light beam 219 passes. In one embodiment, the first optical element 214 includes a prism whose thickness varies along at least one radial direction. In one embodiment, the first optical element 214 includes a wedge-angle prism, aligning the straight beam 219 for refraction.

In one embodiment, the scanning module 202 further includes a second optical element 215 that rotates about a rotation axis 209. The rotation speed of the second optical element 215 is different from the rotation speed of the first optical element 214. The second optical element 215 is used to change the direction of the light beam projected by the first optical element 214. In one embodiment, the second optical element 115 is connected to another driver 217, and the driver 217 drives the second optical element 215 to rotate. The first optical element 214 and the second optical element 215 may be driven by the same or different drivers, so that the first optical element 214 and the second optical element 215 have different rotation speeds and/or rotations, thereby projecting the collimated light beam 219 to the outside space Different directions can scan a larger spatial range. In one embodiment, the controller 218 controls the

drivers

216 and 217 to drive the first optical element 214 and the second optical element 215, respectively. The rotation speeds of the first optical element 214 and the second optical element 215 can be determined according to the area and pattern expected to be scanned in practical applications.

Drives

216 and 217 may include motors or other drives.

In one embodiment, the second optical element 215 includes a pair of opposed non-parallel surfaces through which the light beam passes. In one embodiment, the second optical element 215 includes a prism whose thickness varies along at least one radial direction. In one embodiment, the second optical element 215 includes a wedge angle prism.

In one embodiment, the scanning module 202 further includes a third optical element (not shown) and a driver for driving the third optical element to move. Optionally, the third optical element includes a pair of opposed non-parallel surfaces through which the light beam passes. In one embodiment, the third optical element includes a prism whose thickness varies along at least one radial direction. In one embodiment, the third optical element includes a wedge angle prism. At least two of the first, second and third optical elements rotate at different rotational speeds and/or turns.

The rotation of each optical element in the scanning module 202 can project light into different directions, such as the direction and direction 213 of the projected light 211, thus scanning the space around the distance measuring device 200. When the light 211 projected by the scanning module 202 hits the detection object 201, a part of the light is reflected by the detection object 201 to the distance measuring device 200 in a direction opposite to the projected light 211. The returned light 212 reflected by the detection object 201 passes through the scanning module 202 and enters the collimating element 204.

The detector 205 is placed on the same side of the collimating element 204 as the emitter 203. The detector 205 is used to convert at least part of the returned light passing through the collimating element 204 into an electrical signal.

In one embodiment, each optical element is coated with an antireflection coating. Optionally, the thickness of the antireflection film is equal to or close to the wavelength of the light beam emitted by the emitter 203, which can increase the intensity of the transmitted light beam.

In one embodiment, a filter layer is coated on the surface of an element on the beam propagation path in the distance measuring device, or a filter is provided on the beam propagation path to transmit at least the wavelength band of the beam emitted by the transmitter, Reflect other bands to reduce the noise caused by ambient light to the receiver.

In some embodiments, the transmitter 203 may include a laser diode through which laser pulses in the order of nanoseconds are emitted. Further, the laser pulse receiving time may be determined, for example, by detecting the rising edge time and/or the falling edge time of the electrical signal pulse. In this way, the distance measuring device 200 can calculate the TOF using the pulse reception time information and the pulse emission time information, thereby determining the distance between the detection object 201 and the distance measuring device 200.

The distance and orientation detected by the distance measuring device 200 can be used for remote sensing, obstacle avoidance, mapping, modeling, navigation, and the like. In one embodiment, the distance measuring device of the embodiment of the present invention can be applied to a mobile platform, and the distance measuring device can be installed on the platform body of the mobile platform. A mobile platform with a distance measuring device can measure the external environment, for example, measuring the distance between the mobile platform and obstacles for obstacle avoidance and other purposes, and performing two-dimensional or three-dimensional mapping on the external environment. In some embodiments, the mobile platform includes at least one of an unmanned aerial vehicle, a car, a remote control car, a robot, and a camera. When the distance measuring device is applied to an unmanned aerial vehicle, the platform body is the fuselage of the unmanned aerial vehicle. When the distance measuring device is applied to an automobile, the platform body is the body of the automobile. The car may be a self-driving car or a semi-automatic car, and no restriction is made here. When the distance measuring device is applied to a remote control car, the platform body is the body of the remote control car. When the distance measuring device is applied to a robot, the platform body is a robot. When the distance measuring device is applied to a camera, the platform body is the camera itself.

The technical terms used in the embodiments of the present invention are only used to describe specific embodiments and are not intended to limit the present invention. In this text, the singular forms "a", "the", and "said" are used to include plural forms unless the context clearly dictates otherwise. Further, the use of "including" and/or "comprising" used in the specification refers to the existence of the described features, wholes, steps, operations, elements, and/or components, but does not exclude the presence or addition of one or more Other features, wholes, steps, operations, elements and/or components.

The corresponding structures, materials, actions, and equivalents of all devices or steps and functional elements (if any) in the appended claims are intended to include any structures, materials, or actions used to perform the function in combination with other specifically claimed elements. The description of the present invention is given for the purpose of embodiments and description, but is not intended to be exhaustive or to limit the invention to the disclosed form. Various modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The embodiments described in the present invention can better reveal the principle and practical application of the present invention, and enable those of ordinary skill in the art to understand the present invention.

The flow chart described in the present invention is only an embodiment, and there may be many modifications and changes to this illustration or steps in the present invention without departing from the spirit of the present invention. For example, these steps can be performed in different orders, or certain steps can be added, deleted, or modified. Persons of ordinary skill in the art may understand that all or part of the processes for implementing the above embodiments and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.

Claims

A sampling circuit is characterized by comprising: a time-to-digital conversion module and an analog-to-digital conversion module set in parallel, and the sampling circuit further includes a control module;

Wherein, the time-to-digital conversion module is used to receive the electrical signal converted from the optical pulse signal and compare the electrical signal with a preset threshold to collect time information corresponding to the electrical signal;

The analog-to-digital conversion module is used to receive the electrical signal converted from the optical pulse signal and collect the amplitude of the electrical signal corresponding to the acquisition time within the sampling clock frequency;

The control module is configured to select and calculate signals collected by the time-to-digital conversion module and/or the analog-to-digital conversion module to obtain parameter values of the optical pulse signal.
The sampling circuit according to claim 1, wherein the time-to-digital conversion module includes a plurality of channels, wherein each of the channels includes a comparator and a time-to-digital converter, wherein the first of the comparator The input terminal is used to receive the electrical signal converted from the optical pulse signal, the second input terminal of the comparator is used to receive the preset threshold of the comparator, and the output terminal of the comparator is used to output the result of the comparison operation , The time-to-digital converter is electrically connected to the output end of the comparator, and is used to extract time information corresponding to the electrical signal according to the result of the comparison operation output by the comparator;

Wherein, the preset thresholds of the comparators in the different channels are different.
The sampling circuit according to claim 1, wherein the analog-to-digital conversion module includes at least one analog-to-digital converter for collecting the amplitude of the electrical signal corresponding to the collection time.
The sampling circuit according to claim 1, wherein the control module is used to calculate the selected signal by fitting to restore the pattern of the optical pulse signal;

Or the control module is used to calculate the selected signal by using explicit statistics to obtain the parameter value of the optical pulse signal.
The sampling circuit according to claim 4, wherein the control module collects at least part of the signal of the time-to-digital conversion module and at least part of the signal collected by the analog-to-digital conversion module to perform the fitting.
The sampling circuit according to claim 1, wherein the control module is further configured to convert the sampling of the time-to-digital conversion module into the sampling of the analog-to-digital conversion module;

Or the control module is also used to convert the samples of the analog-to-digital conversion module into the samples of the time-to-digital conversion module.
The sampling circuit according to claim 6, wherein the control module is used to first calculate the sampled signal of the analog-to-digital conversion module by fitting to obtain a pattern of the optical pulse signal, Then, a preset threshold value and corresponding time information are marked on the graph of the light pulse signal.
The sampling circuit according to claim 1, wherein when the control module selects the signal:

When the width of the optical pulse signal is less than the set value of the pulse width, the signal collected by the time-to-digital conversion module is selected; and/or

When the pulse height of the optical pulse signal is less than the set value of the pulse height, the signal collected by the analog-to-digital conversion module is selected; and/or

When the width of the optical pulse signal is greater than the set value of the pulse width and the pulse height of the optical pulse signal is greater than the set value of the pulse height, if the information on the arrival time and pulse width of the optical pulse signal is required to have higher accuracy At this time, at least the signal collected by the time-to-digital conversion module is selected; if higher precision is required for the pulse energy and amplitude information of the optical pulse signal, at least the signal collected by the analog-to-digital conversion module is selected.
The sampling circuit according to claim 1, wherein the parameter value includes at least one of pulse arrival time, pulse width, pulse energy, and amplitude.
A sampling method based on a sampling circuit is characterized by including:

Receiving an electrical signal converted from an optical pulse signal through a time-to-digital conversion module and comparing the electrical signal with a preset threshold to collect time information corresponding to the electrical signal;

Receive the electrical signal converted from the optical pulse signal through the analog-to-digital conversion module, and collect the amplitude signal of the electrical signal corresponding to the acquisition time within the sampling clock frequency;

The signals collected by the time-to-digital conversion module and/or the analog-to-digital conversion module are selected and calculated to obtain the parameter value of the optical pulse signal.
The sampling method according to claim 10, wherein the time-to-digital conversion module includes a plurality of channels, and the plurality of channels receive the electrical signal in parallel and perform a comparison operation on the electrical signal to collect The time information corresponding to the electrical signal.
The sampling method according to claim 11, wherein the plurality of channels are respectively set with different preset thresholds to receive the electrical signals in parallel and perform comparison operations on the electrical signals.
The sampling method according to claim 10, wherein the step of selecting a signal and performing calculation to obtain the parameter value of the optical pulse signal includes:

Calculate the selected signal by fitting to restore the pattern of the optical pulse signal;

Or, the explicit signal is used to calculate the selected signal to obtain the parameter value of the optical pulse signal.
The sampling method according to claim 13, wherein at least a part of the signal of the time-to-digital conversion module and a part of the signal collected by the analog-to-digital conversion module are selected for the fitting.
The sampling method according to claim 10, characterized in that after the signals collected by the time-to-digital conversion module and the analog-to-digital conversion module are selected, before the calculation, the method further includes:

Converting the samples of the time-to-digital conversion module into the samples of the analog-to-digital conversion module;

Or the control module is also used to convert the samples of the analog-to-digital conversion module into the samples of the time-to-digital conversion module.
The sampling method according to claim 15, wherein the sampled signal of the analog-to-digital conversion module is first calculated by fitting to obtain a pattern of the optical pulse signal, and then the optical pulse The preset threshold and corresponding time information are marked on the graphic structure of the signal.
The sampling method according to claim 10, wherein when selecting the signal,

When the width of the optical pulse signal is less than the set value of the pulse width, the signal collected by the time-to-digital conversion module is selected; and/or

When the pulse height of the optical pulse signal is less than the set value of the pulse height, the signal collected by the analog-to-digital conversion module is selected; and/or

When the width of the optical pulse signal is greater than the set value of the pulse width and the pulse height of the optical pulse signal is greater than the set value of the pulse height, if the information on the arrival time and pulse width of the optical pulse signal is required to have higher accuracy At this time, at least the signal collected by the time-to-digital conversion module is selected; if higher precision is required for the pulse energy and amplitude information of the optical pulse signal, at least the signal collected by the analog-to-digital conversion module is selected.
The sampling method according to claim 10, wherein the parameter value includes at least one of pulse arrival time, pulse width, pulse energy, and pulse amplitude.
A distance measuring device, characterized in that it includes:

Light emitting circuit, used to emit light pulse signal;

An optical receiving circuit, configured to receive at least part of the optical signal reflected by the optical pulse signal emitted by the optical transmitting circuit through the object, and convert the received laser signal into an electrical signal;

The sampling circuit according to any one of claims 1 to 9, used for sampling the electrical signal from the laser receiving circuit to obtain a sampling result;

The arithmetic circuit is used for calculating the distance between the object and the distance measuring device according to the sampling result.
A mobile platform is characterized by comprising:

The distance measuring device of claim 19; and

A platform body, and the light emitting circuit of the distance measuring device is installed on the platform body.
The mobile platform of claim 20, wherein the mobile platform includes at least one of an unmanned aerial vehicle, a car, and a robot.