Laser radar signal processing device and method based on I-Rife algorithm

Abstract

The invention discloses a laser radar signal processing device and method based on an I-Rife algorithm, and belongs to the technical field of laser radar signal processing, and the device comprises a trigger module, a data collection module, a signal processing and resolving module, and an upper computer storage and interactive display module. The trigger module is connected with the signal processing and resolving module, the data acquisition module is also connected with the signal processing and resolving module, and the signal processing and resolving module is connected with the upper computer storage and interactive display module; according to the laser radar signal processing device and method based on the I-Rife algorithm, by deploying the I-Rife algorithm at the PL end of the ZYNQ processor, the sub-module pipeline design is achieved in the fixed-point implementation process, the processing speed and the overall performance of the system are improved, and rapid resolving and high-precision distance measurement at the 0.1 ms level are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of laser radar signal processing, and in particular to a laser radar signal processing device and method based on an I-Rife algorithm. Background Art

[0002] With the development of autonomous driving technology, the demand for accurate perception of the vehicle's surrounding environment is growing. As a high-precision sensor that can provide three-dimensional information about the surrounding environment, LiDAR has become an indispensable component of autonomous driving systems. However, existing LiDAR systems still have some challenges in signal acquisition and processing.

[0003] Existing lidar data processing algorithms usually rely on complex mathematical models and a large amount of computing resources, which not only increases the energy consumption of the system, but also limits the speed and real-time performance of data processing. Therefore, the present invention proposes a lidar signal processing device and method based on the I-Rife algorithm. Summary of the invention

[0004] The purpose of the present invention is to provide a lidar signal processing device and method based on the I-Rife algorithm. By deploying the I-Rife algorithm on the ZYNQ PL end, a modular pipeline design is implemented in the fixed-point implementation process, thereby improving the processing speed and the overall performance of the system, and achieving fast solution and high-precision ranging at the 0.1ms level.

[0005] To achieve the above-mentioned purpose, the present invention provides a laser radar signal processing device based on the I-Rife algorithm, including a trigger module, a data acquisition module, a signal processing and solving module, and a host computer storage and interactive display module; the trigger module is connected to the signal processing and solving module, the data acquisition module is also connected to the signal processing and solving module, and the signal processing and solving module is connected to the host computer storage and interactive display module.

[0006] Preferably, the trigger module, the data acquisition module and the signal processing and solving module are connected by digital signal input and output, and the signal processing and solving module is connected to the host computer storage and interactive display module via a network communication cable.

[0007] Preferably, the data acquisition module includes a two-stage operational amplifier unit and an AD conversion unit; the two-stage operational amplifier units are respectively a primary operational amplifier unit and a secondary operational amplifier unit, the primary operational amplifier unit is used to convert the single-ended signal of the analog input into a differential signal, and the secondary operational amplifier unit is responsible for scaling the input signal; the AD conversion unit converts the analog signal into a digital signal and sends it to the processor of the signal processing and solving module, and the sampling clock of the AD conversion unit is provided by a programmable clock chip.

[0008] Preferably, the signal processing and solving module includes a ZYNQ processor, the ZYNQ processor includes a PS end and a PL end for deploying an I-Rife algorithm program, and the host computer storage and interactive display module includes a storage unit and a display unit.

[0009] The present invention also provides a laser radar signal processing method based on the I-Rife algorithm, comprising the following steps:

[0010] Step 1: Initialize the system;

[0011] Step 2: After initialization is completed, wait for a trigger signal, start data acquisition after receiving the trigger signal, and store the raw data obtained by data acquisition;

[0012] Step 3: roughly process the collected data and store them;

[0013] Step 4, correcting the roughly processed data to obtain a correction factor, and calculating the frequency estimation value according to the correction factor;

[0014] Step 5. Design Block Design, add AXI_DMA in Block Design, send the rough processing results and the calculated frequency estimation value to the PS side of the ZYNQ processor, and upload the frequency value to the host computer through the network transmission protocol for storage and display.

[0015] Preferably, the steps of initializing the system in step 1 are:

[0016] S11, perform cross-clock domain processing on the transmission of the solved frequency value and process data, add asynchronous FIFO between PL output and DMA (direct memory access), write enable and write clock in ZYNQ processor are controlled by the derived clock generated by MMCM (mixed mode clock manager) on the PL side, read enable and read clock are controlled by the clock on the PS side, and SPI communication timing is designed and written on the PL side;

[0017] S12, initialize each unit; configure the frequency division factor of the programmable clock chip unit, set the sampling clock frequency, calibrate the VCO of the unit, set the channel output mode, configure the scaling factor of the secondary operational amplifier unit and configure the output mode of the AD conversion unit.

[0018] Preferably, the specific steps of starting data acquisition after receiving the trigger signal in step 2 are: when the trigger module receives the rising edge signal, the secondary operational amplifier unit in the data acquisition module starts to collect data and converts it into a digital signal through the AD unit, stores it and transmits it to the information processing module at the same time.

[0019] Preferably, the steps of roughly processing the collected data in step 3 and storing the data are as follows: performing FFT operation on the sampled data to obtain the full-band spectrum X of the signal. ω , find the peak point ω in the spectrum m and the next largest point ω adjacent to this point m±1 , convert them into frequency values ​​and store them in FIFO.

[0020] Preferably, the correction factor is obtained by correction in step 4, and the steps of calculating the frequency estimation value according to the correction factor are as follows:

[0021] S41, after receiving the signal transmitted by the AD unit, digital bandpass filtering is performed on it, and the filter is set to a narrow-band bandpass filter with a variable passband to filter out the influence of out-of-band noise;

[0022] S42, determine the correction direction of the processed signal, and obtain the correction factor Δω, specifically: when |X ω+1 |<|X ω-1 |, the correction direction is positive, a=1; when |X ω+1 |>|X ω-1 |, the correction direction is negative, a = -1; the correction factor Δω is calculated as follows:

[0023]

[0024] S43. After obtaining the correction factor, calculate the frequency estimate according to the correction factor

[0025]

[0026] where f s is the sampling rate of the system.

[0027] Preferably, in step 5, the frequency value is uploaded to the host computer through the network transmission protocol for storage and display as follows: after the information processing and solving module sends the FFT result and the frequency value to the host computer through the network communication protocol, the frequency-distance conversion is first performed, the storage unit in the information processing and solving module will store the distance values ​​of the most recent few data packets, and the display unit will draw points and connect lines for the previous packet of FFT results, and display them in real time.

[0028] Therefore, the present invention adopts the above-mentioned laser radar signal processing device and method based on the I-Rife algorithm, which has the following advantages:

[0029] 1. By deploying the I-Rife algorithm on the ZYNQ PL side, a modular pipeline design is implemented in the fixed-point implementation process, which improves the processing speed and overall system performance, and achieves fast solution and high-precision ranging at the 0.1ms level;

[0030] 2. The use of narrow-band digital filtering with variable passband, single-ended to differential conversion and other module units optimizes the signal processing process, improves the accuracy of signal processing, and effectively reduces the impact of noise;

[0031] 3. The host computer uses an integrated storage unit and display unit to realize the functions of process data storage and display interaction, and can display the FFT spectrum and the refined spectrum information obtained after I-Rife algorithm processing in real time.

[0032] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of a frequency modulated continuous wave intermediate frequency signal generation principle of a laser radar signal processing device and method based on the I-Rife algorithm of the present invention;

[0034] Figure 2 This is an overall flow chart of a laser radar signal processing method based on the I-Rife algorithm of the present invention;

[0035] Figure 3 A flowchart of a programmable clock chip configuration for a laser radar signal processing method based on an I-Rife algorithm of the present invention;

[0036] Figure 4 The specific implementation process of the I-Rife algorithm of the laser radar signal processing method based on the I-Rife algorithm of the present invention;

[0037] Figure 5 This is a diagram of the host computer interface of a laser radar signal processing device based on the I-Rife algorithm of the present invention. DETAILED DESCRIPTION

[0038] Example

[0039] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0040] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] like Figure 1-5 As shown, it includes a trigger module, a data acquisition module, a signal processing and solving module, and a host computer storage and interactive display module; the trigger module is connected to the signal processing and solving module, the data acquisition module is also connected to the signal processing and solving module, and the signal processing and solving module is connected to the host computer storage and interactive display module. The trigger module, the data acquisition module and the signal processing and solving module are connected using digital signal input and output, and the signal processing and solving module is connected to the host computer storage and interactive display module through a network communication cable. The data acquisition module includes a two-stage operational amplifier unit and an AD conversion unit; the two-stage operational amplifier units are respectively a primary operational amplifier unit and a secondary operational amplifier unit, the primary operational amplifier unit is used to convert the single-ended signal of the analog input into a differential signal, and the secondary operational amplifier unit is responsible for scaling the input signal; the AD conversion unit converts the analog signal into a digital signal and sends it to the processor of the signal processing and solving module, and the sampling clock of the AD conversion unit is provided by a programmable clock chip. The signal processing and solving module includes a ZYNQ processor, the ZYNQ processor includes a PS end and a PL end for deploying an I-Rife algorithm program, and the host computer storage and interactive display module includes a storage unit and a display unit.

[0042] The present invention also provides a laser radar signal processing method based on the I-Rife algorithm, comprising the following steps:

[0043] Step 1: Initialize the system:

[0044] S11, perform cross-clock domain processing on the transmission of the solved frequency value and process data, add asynchronous FIFO between PL output and DMA (direct memory access), write enable and write clock in ZYNQ processor are controlled by the derived clock generated by MMCM (mixed mode clock manager) on the PL side, read enable and read clock are controlled by the clock on the PS side, and SPI communication timing is designed and written on the PL side;

[0045] S12, initialize each unit; configure the frequency division factor of the programmable clock chip unit, set the sampling clock frequency, calibrate the VCO of the unit, set the channel output mode, configure the scaling factor of the secondary operational amplifier unit and configure the output mode of the AD conversion unit.

[0046] Step 2: After initialization is completed, wait for the trigger signal, start data acquisition after receiving the trigger signal, and store the raw data obtained from the data acquisition:

[0047] When the trigger module receives the rising edge signal, the secondary operational amplifier unit in the data acquisition module starts to collect data and converts it into a digital signal through the AD unit, which is stored and transmitted to the information processing module at the same time.

[0048] Step 3: Roughly process the collected data and store it:

[0049] Perform FFT operation on the sampled data to obtain the full-band spectrum X of the signal ω , find the peak point ω in the spectrum m and the next largest point ω adjacent to this point m±1 , convert them into frequency values ​​and store them in FIFO.

[0050] Step 4: Correct the roughly processed data to obtain the correction factor, and calculate the frequency estimate based on the correction factor:

[0051] S41, after receiving the signal transmitted by the AD unit, digital bandpass filtering is performed on it, and the filter is set to a narrow-band bandpass filter with a variable passband to filter out the influence of out-of-band noise;

[0052] S42, determine the correction direction of the processed signal and obtain the correction factor Δω, the method is as follows: when |X ω+1 |<|X ω-1 |, the correction direction is positive, a=1; when |X ω+1 |>|X ω-1 |, the correction direction is negative, a = -1; the correction factor Δω is calculated as follows:

[0053]

[0054] S43. After obtaining the correction factor, calculate the frequency estimate according to the correction factor

[0055]

[0056] where f s is the sampling rate of the system.

[0057] Step 5. Design Block Design, add AXI_DMA in Block Design, send the rough processing results and the calculated frequency estimation value to the PS side of the ZYNQ processor, and upload the frequency value to the host computer for storage and display through the network transmission protocol:

[0058] After the information processing and solving module sends the FFT results and frequency values ​​to the host computer through the network communication protocol, it first performs frequency-distance conversion. The storage unit in the information processing and solving module will store the distance values ​​of the most recent few data packets, and the display unit will draw points and connect lines for the previous FFT result packet and display it in real time.

[0059] The specific implementation of a lidar signal processing device and method based on the I-Rife algorithm of the present invention is as follows: There is an optical path difference between the frequency-modulated continuous-wave transmitted signal and the echo signal, resulting in a time delay difference between the two when they reach the detector. The frequency functions of the two are as Figure 1 shown, where f0 is the initial frequency, B is the bandwidth, T is the period of a complete triangular wave, τ is the delay time between the echo signal and the transmitted signal, and fIF is the frequency value of the intermediate-frequency signal. Figure 1 The solid line in

[0060] represents the optical frequency function of the transmitted signal, and the dashed line represents the optical frequency function of the echo signal. The time for light to pass through the target and return is τ, that is, the echo signal has a time delay difference of τ relative to the transmitted signal. It can be obtained that the median frequency is a constant value fIF in the i-th period and (i - 1)T + τ < t < iT. Figure 2 The entire system program is driven as Figure 3 shown. When the system is powered on, each module is initialized.

[0061] This is the initialization configuration process for the programmable clock network chip. After initialization, the system first enters the standby state, waiting for a trigger signal, which is the TTL level input of a 4KHz square wave. After receiving the trigger signal, the AD link is started and sampling begins simultaneously. After sampling is completed, data frequency calculation starts. First, a rough estimate is made by performing an FFT on the sampling sequence. According to the FFT result, the corresponding FIR narrowband filter coefficients are selected for filtering. At the same time, the correction direction is determined, the frequency correction factor is calculated, and spectrum refinement correction is performed. After obtaining the frequency, it is sent to the DDR in the PS through the HP interface using AXI_DMA. At the PS end, the DDR is read, and the frequency value is sent to the host computer through the network port. Figure 4 The I-Rife process of the solution algorithm is as (n) shown. After the AD acquisition sequence x

[0062] Figure 5 is sent into the system, the FFT result is obtained. After determining the correction direction, the correction factor is calculated, and then the final solution frequency value is obtained through frequency interpolation.

[0063] Therefore, the laser radar signal processing device and method based on the I-Rife algorithm of the present invention, by deploying the I-Rife algorithm on the ZYNQ PL end, realizes the modular pipeline design in the fixed-point implementation process, improves the processing speed and the overall performance of the system, and realizes fast solution and high-precision ranging at the level of 0.1ms. And it uses narrow-band bandpass digital filtering with variable passband, single-ended to differential and other module units to optimize the signal processing process, improve the accuracy of signal processing, and effectively reduce the influence of noise. At the same time, the host computer uses an integrated storage unit and display unit to realize the functions of process data storage and display interaction, which can display the FFT spectrum and the refined spectrum information obtained after processing by the I-Rife algorithm in real time.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A laser radar signal processing device based on the I-Rife algorithm, characterized in that: It includes a trigger module, a data acquisition module, a signal processing and solving module, and a host computer storage and interactive display module; the trigger module is connected to the signal processing and solving module, the data acquisition module is also connected to the signal processing and solving module, and the signal processing and solving module is connected to the host computer storage and interactive display module.

2. The laser radar signal processing device based on the I-Rife algorithm according to claim 1, characterized in that: The trigger module, the data acquisition module and the signal processing and solving module are connected by digital signal input and output, and the signal processing and solving module is connected with the host computer storage and interactive display module through a network communication cable.

3. The laser radar signal processing device based on the I-Rife algorithm according to claim 2, characterized in that: The data acquisition module includes a two-stage operational amplifier unit and an AD conversion unit; the two-stage operational amplifier unit is respectively a primary operational amplifier unit and a secondary operational amplifier unit, the primary operational amplifier unit is used to convert the single-ended signal of the analog input into a differential signal, and the secondary operational amplifier unit is responsible for scaling the input signal; the AD conversion unit converts the analog signal into a digital signal and sends it to the processor of the signal processing and solving module, and the sampling clock of the AD conversion unit is provided by a programmable clock chip.

4. The laser radar signal processing device based on the I-Rife algorithm according to claim 3, characterized in that: The signal processing and solving module includes a ZYNQ processor, and the ZYNQ processor includes a PS end and a PL end for deploying an I-Rife algorithm program. The host computer storage and interactive display module includes a storage unit and a display unit.

5. A laser radar signal processing method based on I-Rife algorithm, characterized in that: The following steps are involved: Step 1: Initialize the system; Step 2: After initialization is completed, wait for a trigger signal, start data acquisition after receiving the trigger signal, and store the raw data obtained by data acquisition; Step 3: roughly process the collected data and store them; Step 4, correcting the roughly processed data to obtain a correction factor, and calculating the frequency estimation value according to the correction factor; Step 5. Design Block Design, add AXI_DMA in Block Design, send the rough processing results and the calculated frequency estimation value to the PS side of the ZYNQ processor, and upload the frequency value to the host computer through the network transmission protocol for storage and display.

6. The laser radar signal processing method based on the I-Rife algorithm according to claim 5, characterized in that: The steps for system initialization in step 1 are: S11. Perform cross-clock domain processing on the transmission of the calculated frequency value and process data, and add an asynchronous FIFO between the PL output and the DMA; in the ZYNQ processor, the write enable and write clock are controlled by the derived clock generated by the MMCM on the PL side, and the read enable and read clock are controlled by the clock on the PS side. Design and write the SPI communication timing on the PL side; S12, initialize each unit; configure the frequency division factor of the programmable clock chip unit, set the sampling clock frequency, calibrate the VCO of the unit, set the channel output mode, configure the scaling factor of the secondary operational amplifier unit and configure the output mode of the AD conversion unit.

7. The laser radar signal processing method based on the I-Rife algorithm according to claim 6, characterized in that: The specific steps of receiving the trigger signal and starting data acquisition in step 2 are as follows: when the trigger module receives the rising edge signal, the secondary operational amplifier unit in the data acquisition module starts to collect data and converts it into a digital signal through the AD unit, stores it and transmits it to the information processing module at the same time.

8. The laser radar signal processing method based on the I-Rife algorithm according to claim 7, characterized in that: In step 3, the collected data is roughly processed and stored as follows: FFT operation is performed on the sampled data to obtain the full-band spectrum X of the signal. ω , find the peak point ω in the spectrum m and the next largest point ω adjacent to this point m±1 , convert them into frequency values ​​and store them in FIFO.

9. The laser radar signal processing method based on the I-Rife algorithm according to claim 8, characterized in that: The correction factor is obtained by correction in step 4, and the steps for calculating the frequency estimate value according to the correction factor are as follows: S41, after receiving the signal transmitted by the AD unit, digital bandpass filtering is performed on it, and the filter is set to a narrow-band bandpass filter with a variable passband to filter out the influence of out-of-band noise; S42, determine the correction direction of the processed signal, and obtain the correction factor Δω, specifically: when |X ω+1 |<|X ω-1 |, the correction direction is positive, and a=1; when |X ω+1 |>|X ω-1 |, the correction direction is negative, and a=-1 at this time; the correction factor Δω is calculated as follows: S43. After obtaining the correction factor, calculate the frequency estimate according to the correction factor where f s is the sampling rate of the system.

10. The laser radar signal processing method based on the I-Rife algorithm according to claim 9, characterized in that: In step 5, the frequency value is uploaded to the host computer through the network transmission protocol for storage and display. The process is as follows: After the information processing and solving module sends the FFT result and frequency value to the host computer through the network communication protocol, the frequency-distance conversion is first performed. The storage unit in the information processing and solving module stores the distance value of the data packet, and the display unit draws points and connects lines for the previous packet of FFT results, and displays it in real time.

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