Disclosure of Invention
This section is intended to outline some aspects of embodiments of the invention and to briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section as well as in the description summary and in the title of the application, to avoid obscuring the purpose of this section, the description summary and the title of the invention, which should not be used to limit the scope of the invention.
The present invention has been made in view of the above-mentioned existing problems with limited application to very close range object detection sensing and environmental modeling.
Therefore, the invention provides a method and a system for sensing based on a very close millimeter wave radar, which can perfect object modeling and detection sensing.
In order to solve the technical problems, the invention provides the following technical scheme: radiating an FMCW signal to the target using the radio frequency antenna module; receiving radar echo signals reflected by the target; converting the signal into an intermediate frequency signal, and sampling by using an ADC; processing the received signal and outputting the detected target; measuring the distance, speed and angle of the target; and transmitting data to obtain the perception information.
As a preferable scheme based on the ultra-short distance millimeter wave radar sensing method, the invention comprises the following steps: outputting the FMCW signal includes receiving a signal using a radio frequency transceiver module; separating the transmit signal and the receive signal according to the signal frequency; controlling the signals, amplifying and outputting the filtered signals, and mixing the filtered signals; generating an oscillation signal, and mixing the oscillation signal with filtering to output; the signal is conditioned to produce a baseband signal and output.
As a preferable scheme based on the ultra-short distance millimeter wave radar sensing method, the invention comprises the following steps: the method specifically comprises the steps of utilizing a core processor to control a DAC to generate a modulation signal before outputting the FMCW signal; driving the radio frequency transceiver module to generate a constant-amplitude frequency modulation continuous wave signal; using a directional coupler, wherein a part of the local oscillation signals enter a mixer to form local oscillation signals; another part enters the circulator to form a transmitting signal by using the radio frequency antenna module.
As a preferable scheme based on the ultra-short distance millimeter wave radar sensing method, the invention comprises the following steps: receiving the radar echo signal comprises radiating a radio frequency signal into space by using the transmitting antenna; the transmitting signal is reflected by the target to form an echo signal; the receiving antenna receives the echo signal; and transmitting the data to the radio frequency transceiver module.
As a preferable scheme based on the ultra-short distance millimeter wave radar sensing method, the invention comprises the following steps: converting the signal includes multiplying the received signal by the local oscillator signal by a receiver in the radio frequency transceiver module; obtaining a frequency-converted intermediate frequency signal by using a low-pass filter; the intermediate frequency signal is converted to a digital signal using an ADC and sampled.
As a preferable scheme based on the ultra-short distance millimeter wave radar sensing method, the invention comprises the following steps: processing the received signal includes outputting the down-converted intermediate frequency signal to a signal processing module; the intermediate frequency signal is converted from an analog domain to a digital domain, and the digital signal is obtained; performing numerical calculation processing on the digital signal by using a DSP; the output is detected for the target.
As a preferable scheme based on the ultra-short distance millimeter wave radar sensing method, the invention comprises the following steps: measuring and transmitting data comprises measuring the distance between a rising edge and a falling edge by utilizing the echo signal delay in triangle frequency change; calculating the distance and the speed of the target by using the frequency difference between the rising edge and the falling edge; the signal processor performs two-dimensional FFT on the signals received by the receiving antenna array, and then jointly processes a two-dimensional FFT matrix to obtain the target arrival angle; and transmitting the data by using a data input/output module.
As a preferable scheme based on the ultra-short distance millimeter wave radar sensing system, the invention comprises the following steps: the radio frequency antenna module adopts patch single-array element antennas and comprises two transmitting antennas and four receiving antennas, the lengths of feeder lines are consistent, radio frequency signals are radiated to a space through the transmitting antennas, and the receiving antennas receive electromagnetic wave signals in the space and output the electromagnetic wave signals to the receiver in the radio frequency transceiver module; the radio frequency transceiver module adopts a linear frequency modulation continuous wave system and comprises a receiver, a transmitting channel and a receiving channel, and generates the FMCW baseband signal, and the signal is down-converted to the intermediate frequency signal through the receiver and is output to the signal processing module in a formatted form.
As a preferable scheme based on the ultra-short distance millimeter wave radar sensing system, the invention comprises the following steps: the signal processing module is connected with the radio frequency receiving and transmitting module and comprises an MCU and a DSP, wherein the MCU controls the working time sequence, the system logic, the output interface of radar processing result data and the acquisition of the digital signal of the radio frequency receiving and transmitting the data to the DSP, and the DSP performs tracking measurement on the detected target after obtaining the data information; the data input/output module performs data transmission through the CAN bus, transmits radar processing results to the outside for use, establishes data interaction, and transmits information required by the radar system from the outside to the inside of the system.
The invention has the beneficial effects that: the invention can perfect environment modeling and object classification in a very close range, is very important for developing advanced driving assistance algorithm and automatic driving function, has a larger FOV, ensures fewer sensors for sensing the surrounding 360-degree environment, and reduces detection sensing cost; and the height measuring device has a height measuring function, and ensures the measurement in the height direction.
Detailed Description
So that the manner in which the above recited objects, features and advantages of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments, some of which are illustrated in the appended drawings. All other embodiments, which can be made by one of ordinary skill in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways other than those described herein, and persons skilled in the art will readily appreciate that the present invention is not limited to the specific embodiments disclosed below.
Further, reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic can be included in at least one implementation of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.
While the embodiments of the present invention have been illustrated and described in detail in the drawings, the cross-sectional view of the device structure is not to scale in the general sense for ease of illustration, and the drawings are merely exemplary and should not be construed as limiting the scope of the invention. In addition, the three-dimensional dimensions of length, width and depth should be included in actual fabrication.
Also in the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper, lower, inner and outer", etc. are based on the orientation or positional relationship shown in the drawings, are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the apparatus or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first, second, or third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
The terms "mounted, connected, and coupled" should be construed broadly in this disclosure unless otherwise specifically indicated and defined, such as: can be fixed connection, detachable connection or integral connection; it may also be a mechanical connection, an electrical connection, or a direct connection, or may be indirectly connected through an intermediate medium, or may be a communication between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
Example 1
Referring to fig. 1, for a first embodiment of the present invention, there is provided a very close range millimeter wave radar sensing method, as in fig. 1, comprising radiating FMCW signals to a target using a radio frequency antenna module 100; receiving radar echo signals reflected by a target; converting the signal into an intermediate frequency signal, and sampling by using an ADC; processing the received signal and outputting a detected target; measuring the distance, speed and angle of the target; and transmitting data to obtain the perception information. The attenuation of millimeter waves when the millimeter waves are transmitted by using an atmospheric window is small, the millimeter waves are less influenced by natural light and a heat radiation source, and the low-elevation precision tracking radar and the imaging radar can be realized by using the narrow beam and low side lobe performance of the millimeter wave antenna; the FMCW radar emits continuous waves with frequency variation in a sweep period, an echo reflected by an object has a certain frequency difference with an emitted signal, distance and speed information between a target and the radar can be obtained by measuring the frequency difference, the performance of measuring the distance and the speed of the target by the FMCW radar is irrelevant to illumination conditions of surrounding environments, and an additional auxiliary light source is not needed to provide illumination.
Referring to fig. 1, a method for sensing a millimeter wave radar based on a very close distance according to the present embodiment includes the following steps,
s1: the FMCW signal is radiated to the target using the radio frequency antenna module 100. This step is to be noted, the output FMCW signal includes,
controlling the DAC to generate a modulation signal by using a core processor;
driving the radio frequency transceiver module 200 to generate a constant-amplitude frequency modulation continuous wave signal;
using a directional coupler, wherein a part of the local oscillation signals enter a mixer to form local oscillation signals;
another part enters the circulator to form a transmission signal using the radio frequency antenna module 100.
Further, the output signal further specifically includes,
receiving a signal by using the radio frequency transceiver module 200, and separating a transmission signal and a reception signal according to a signal frequency;
a control signal for amplifying and mixing the filtered output;
generating an oscillation signal, and mixing the oscillation signal with filtering to output;
and adjusting the signal to generate a baseband signal and outputting the baseband signal.
S2: and receiving radar echo signals reflected by the target. Wherein, the receiving radar echo signals comprises,
the radio frequency signal is radiated to the space by the transmitting antenna 101;
the transmitting signal is reflected by the target to form an echo signal;
the receiving antenna 102 receives the echo signal;
to the rf transceiver module 200.
S3: the signal is converted to an intermediate frequency signal and sampled by an ADC. This step also requires that the converted signal comprises,
the receiver 201 in the radio frequency transceiver module 200 multiplies the received signal by the local oscillator signal;
obtaining a frequency-converted intermediate frequency signal by using a low-pass filter;
converting the intermediate frequency signal into a digital signal by using an ADC (analog to digital converter), and sampling; the data volume is reduced on the premise that the sampling processing meets the Nyquist sampling theorem.
S4: the received signal is processed and a detected object is output. It should also be noted that in this context,
outputting the down-converted intermediate frequency signal to the signal processing module 300;
the intermediate frequency signal is converted from an analog domain to a digital domain, and a digital signal is obtained;
performing numerical calculation processing on the digital signal by using a DSP;
outputting the detected target.
S5: the distance, speed and angle of the target are measured. It should be noted that in this step,
measuring the distance between the rising edge and the falling edge by utilizing the echo signal delay in the triangle frequency change;
calculating the distance and speed of the target by using the frequency difference between the rising edge and the falling edge;
the signal processor performs two-dimensional FFT on the signals received by the array of the receiving antenna 102, and then jointly processes the two-dimensional FFT matrix to obtain the target arrival angle.
S6: and transmitting the data in a CAN or Ethernet form to obtain the perception information.
Preferably, the method of the embodiment can realize effective detection of the minimum distance of 5cm, has high ranging precision and wide detection angle range, can provide space three-dimensional information and speed information of an object, and can effectively sense a close-range target. The method has great significance for accurate measurement of free parking spaces and accurate perception of obstacles around the vehicle body.
Scene one:
in the prior art, the millimeter wave radar detects and perceives a middle and long-distance target, the distance resolution is about 10cm to 50cm, and the performance of the millimeter wave radar sensor is difficult to meet for the perception of a near area of a vehicle body, and the application of the millimeter wave radar sensor in the detection and perception of an extremely-close object and the environment modeling is limited. In order to verify that the embodiment can realize effective detection of the minimum distance of 5cm, has high ranging precision and wide detection angle range, can provide space three-dimensional information and speed information of an object, and can effectively sense a close-range target. By setting different target distances for testing respectively the traditional radar and the present radar system,
preferably, the distance test is performed using the angle reverse, the angle reverse is placed at different distances, the conventional radar and the radar are used for testing respectively, and the real test results are shown in tables 1, 2 and 3 below.
Table 1: testing at different distances.
According to the distance ratio test result, the traditional radar can not measure the distance within 20cm, and the radar can measure the target of 8 cm; the traditional radar range error is about 10cm, and the radar range error is only 2cm.
Table 2: angular reverse position, pitch angle 0 °, distance 5m:
table 3: angular reverse position, azimuth angle 0 °, distance 1m:
according to the angle ratio test result, the FOV of the radar can reach 40 degrees, the pitch angle range of the radar is only 10 degrees, and the blind area of the radar is greatly reduced when the radar is detected at a short distance; the radar has the angle measurement precision basically same as that of the traditional radar, and the angle measurement precision is not lost due to the increase of the FOV.
It should be appreciated that embodiments of the invention may be implemented or realized by computer hardware, a combination of hardware and software, or by computer instructions stored in a non-transitory computer readable memory. The methods may be implemented in a computer program using standard programming techniques, including a non-transitory computer readable storage medium configured with a computer program, where the storage medium so configured causes a computer to operate in a specific and predefined manner, in accordance with the methods and drawings described in the specific embodiments. Each program may be implemented in a high level procedural or object oriented programming language to communicate with a computer system. However, the program(s) can be implemented in assembly or machine language, if desired. In any case, the language may be a compiled or interpreted language. Furthermore, the program can be run on a programmed application specific integrated circuit for this purpose.
Furthermore, the operations of the processes described herein may be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The processes (or variations and/or combinations thereof) described herein may be performed under control of one or more computer systems configured with executable instructions, and may be implemented as code (e.g., executable instructions, one or more computer programs, or one or more applications), by hardware, or combinations thereof, collectively executing on one or more processors. The computer program includes a plurality of instructions executable by one or more processors.
Further, the method may be implemented in any type of computing platform operatively connected to a suitable computing platform, including, but not limited to, a personal computer, mini-computer, mainframe, workstation, network or distributed computing environment, separate or integrated computer platform, or in communication with a charged particle tool or other imaging device, and so forth. Aspects of the invention may be implemented in machine-readable code stored on a non-transitory storage medium or device, whether removable or integrated into a computing platform, such as a hard disk, optical read and/or write storage medium, RAM, ROM, etc., such that it is readable by a programmable computer, which when read by a computer, is operable to configure and operate the computer to perform the processes described herein. Further, the machine readable code, or portions thereof, may be transmitted over a wired or wireless network. When such media includes instructions or programs that, in conjunction with a microprocessor or other data processor, implement the steps described above, the invention described herein includes these and other different types of non-transitory computer-readable storage media. The invention also includes the computer itself when programmed according to the methods and techniques of the present invention. The computer program can be applied to the input data to perform the functions described herein, thereby converting the input data to generate output data that is stored to the non-volatile memory. The output information may also be applied to one or more output devices such as a display. In a preferred embodiment of the invention, the transformed data represents physical and tangible objects, including specific visual depictions of physical and tangible objects produced on a display.
Example 2
Referring to fig. 2 to 7, in a second embodiment of the present invention, unlike the first embodiment, there is provided a very close range millimeter wave radar sensing system, as shown in fig. 3, which includes a radio frequency antenna module 100, a radio frequency transceiver module 200, a signal processing module 300 and a data input/output module 400, the radio frequency antenna module 100 employs patch unit antennas, including a transmitting antenna 101 and a receiving antenna 102, the transmitting antenna 101 is two, the receiving antennas 102 are four, the length of a feeder line is kept consistent, the radio frequency signal is radiated to a space through the transmitting antenna 101, the receiving antenna 102 receives electromagnetic wave signals in the space, and outputs the electromagnetic wave signals to a receiver 201 in the radio frequency transceiver module 200; the radio frequency transceiver module 200 adopts a linear frequency modulation continuous wave system and comprises a receiver 201, a transmitting channel 202 and a receiving channel 203, wherein the radio frequency transceiver module 200 generates an FMCW baseband signal, and the signal is down-converted to an intermediate frequency signal through the receiver 201 and is output to the signal processing module 300 in a formatted form; the signal processing module 300 is connected with the radio frequency transceiver module 200 and comprises an MCU301 and a DSP302, wherein the MCU301 controls the working time sequence, system logic, an output interface of radar processing result data and the acquisition of digital signals of the radio frequency transceiver module 200, and transmits the data to the DSP302, and the DSP302 performs tracking measurement on a detected target after obtaining data information; the data input/output module 400 performs data transmission through the CAN bus 401, transmits the radar processing result to the outside for use, establishes data interaction, and transmits information required by the radar system from the outside into the system.
Specifically, referring to fig. 2, the transmitting antenna 101 and the receiving antenna 102 keep consistent in feeder length, and the Y-direction antenna element spacing d_el_2=8 mm; 1 in the receiving antenna 102 coincides with 2, x coordinates, Y-direction spacing d_el_1=8 mm; 2, 3, 4, y coordinates in the receiving antenna 102 are consistent, 3 and 2 in the receiving antenna 102 are separated by d_az, 4 and 3 in the receiving antenna 102 are separated by d_az, d_az=4mm; wherein d is the array element interval, θ is the unilateral maximum grating lobe angle, wherein C is the light speed 3e8, fc is the center frequency 79e9Hz, and the antenna array spacing is calculated according to the following formula:
the relation between the array element spacing and the maximum grating lobe is as follows:
further, referring to fig. 5 and 6, the radio frequency transceiver module 200 completes the generation of FMCW baseband signals, up-converts the signals, then radiates the desired frequency radio frequency signals into space through the transmitting antenna 101, and when receiving the signals, the signals in space are input to the receiver 201 through the receiving antenna 102, the receiver 201 completes the down-conversion of the signals, and completes the ADC operation, and then outputs the down-converted intermediate frequency signals to the signal processing module 300.DSP302 performs baseband signal processing, including fourier transform of the signal, target detection, measurement, and target tracking, RAM and FLASH provide the necessary memory for computation and programming.
Preferably, referring to fig. 7, the synthesizer generates an FMCW transmit signal, radiates the signal to space through a Tx (transmit) antenna, for example, the signal hits an automobile return radar echo signal, receives the echo signal through an Rx (receive antenna), mixes with a reference signal of the transmit signal after passing through a low noise amplifier, obtains an intermediate frequency signal (IF signal), and performs ADC sampling after passing through a low pass filter, thereby obtaining a digital signal.
As used in this application, the terms "component," "module," "system," and the like are intended to refer to a computer-related entity, either hardware, firmware, a combination of hardware and software, or software in execution. For example, the components may be, but are not limited to: a process running on a processor, an object, an executable, a thread of execution, a program, and/or a computer. By way of example, both an application running on a computing device and the computing device can be a component. One or more components may reside within a process and/or thread of execution and a component may be localized on one computer and/or distributed between two or more computers. Furthermore, these components can execute from various computer readable media having various data structures thereon. The components may communicate by way of local and/or remote processes such as in accordance with a signal having one or more data packets (e.g., data from one component interacting with another component in a local system, distributed system, and/or across a network such as the internet with other systems by way of the signal).
It should be noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solution of the present invention may be modified or substituted without departing from the spirit and scope of the technical solution of the present invention, which is intended to be covered in the scope of the claims of the present invention.