APPARATUS FOR DRIVER ASSISTANCE AND METHOD OF CONTROLLING THE SAME

An apparatus for driver assistance includes a radar installed to a vehicle, having a sensing area outside the vehicle, and configured to provide object data, and a controller configured to identify a distance to an object from the vehicle and a moving speed of the object based on the object data. The radar includes an antenna array, a signal processing circuit configured to provide a transmission signal to the antenna array to transmit radio waves and acquire a reception signal corresponding to radio waves received by the antenna array, and a signal processor configured to control the signal processing circuit to provide a pre-chirp signal including a plurality of pre-chirps and a main chirp signal including a plurality of main chirps to the antenna array. The number of pre-chirps is less than the number of main chirps.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Korean Patent Application No. 10-2022-0130061, filed on Oct. 11, 2022 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety.

BACKGROUND

1. Technical Field

Embodiments of the present disclosure generally relate to an apparatus including a radar and a method of controlling the same.

2. Description of the Related Art

Vehicles are the most common transportation in modern society, and the number of people using the vehicles is increasing. Although there are advantages such as easy long-distance travel and comfortable living with the development of a vehicle technology, a problem that road traffic conditions deteriorate and traffic congestion becomes serious in densely populated places often occurs.

Recently, research on vehicles equipped with an advanced driver assist system (ADAS) for actively providing information on a vehicle condition, a driver condition, and/or a surrounding environment in order to reduce a driver's burden, provide assistance in driving a vehicle, and enhance convenience is actively progressing.

As examples of the ADASs mounted on the vehicle, there are lane departure warning (LDW), lane keeping assist (LKA), high beam assist (HBA), autonomous emergency braking (AEB), traffic sign recognition (TSR), adaptive cruise control (ACC), blind spot detection (BSD), etc.

The ADAS may collect information or data on a surrounding environment and process the collected information. In addition, the ADAS may recognize objects and design a route for the vehicle to travel based on the processing of the collected information.

SUMMARY

Therefore, it is an aspect of the present disclosure to provide an apparatus including a radar and a method of controlling the same.

In accordance with one aspect of the present disclosure, an apparatus for driver assistance includes a radar installed on a vehicle, having a sensing area outside the vehicle, and configured to provide object data, and a controller configured to identify a distance to an object around the vehicle and a moving speed of the object based on a processing the object data. The radar includes an antenna array, a signal processing circuit configured to provide a transmission signal to the antenna array to transmit radio waves and acquire a reception signal corresponding to radio waves received by the antenna array, and a signal processor configured to control the signal processing circuit to provide a pre-chirp signal including a plurality of pre-chirps and a main chirp signal including a plurality of main chirps to the antenna array. The number of pre-chirps is smaller than the number of main chirps.

The antenna array may sequentially transmit radio waves corresponding to the pre-chirp signal and radio waves corresponding to the main chirp signal, and receive radio waves reflected from the object around the vehicle.

The signal processing circuit may acquire a first reflection chirp signal corresponding to the radio waves reflected from the object around the vehicle while transmitting the pre-chirp signal, mix the pre-chirp signal with the first reflection chirp signal, and provide a first intermediate frequency signal in which the pre-chirp signal and the first reflection chirp signal are mixed to the signal processor.

The signal processor may provide the object data including information on the distance to the object and the moving speed of the object based on the first intermediate frequency signal, and provide a bin mask corresponding to at least one bin not including data corresponding to the distance to the object.

The signal processor may transform the plurality of first intermediate frequency signals corresponding to the plurality of pre-chirps into a plurality of pieces of first frequency domain data through a fast Fourier transform, respectively, and store a first frequency domain matrix including the plurality of pieces of first frequency domain data.

The signal processor may transform data corresponding to the same frequency among the plurality of pieces of first frequency domain data into a plurality of pieces of first phase domain data through the fast Fourier transform, and store a first phase domain matrix including the plurality of pieces of first phase domain data.

The signal processor may provide the object data including information on the distance to the object and the moving speed of the object based on the plurality of pieces of first phase domain data included in the first phase domain matrix.

The phase domain matrix may include a plurality of first bins corresponding to different distances. The signal processor may provide a bin mask corresponding to at least one bin not including data corresponding to the distance to the object among the plurality of first bins.

The signal processing circuit may acquire a second reflection chirp signal corresponding to the radio waves reflected from the object around the vehicle while transmitting the main chirp signal, mix the main chirp signal with the second reflection chirp signal, and provide a second intermediate frequency signal in which the main chirp signal and the second reflection chirp signal are mixed to the signal processor. The signal processor may process the second intermediate frequency signal, filter the processed signal using the bin mask, and provide the object data including the information on the distance to the object and the moving speed of the object based on the filtered signal.

The signal processor may transform a plurality of second intermediate frequency signals corresponding to the plurality of pre-chirps into a plurality of pieces of second frequency domain data through a fast Fourier transform, respectively, filter data corresponding to the at least one bin among the plurality of pieces of second frequency domain data using the bin mask, and store a second frequency domain matrix including the plurality of pieces of filtered second frequency domain data.

The signal processor may transform data corresponding to the same frequency among the plurality of pieces of filtered second frequency domain data into a plurality of pieces of second phase domain data through the fast Fourier transform, and store a second phase domain matrix including the plurality of pieces of second phase domain data.

The signal processor may provide the object data including the information on the distance to the object and the moving speed of the object based on the plurality of pieces of second phase domain data included in the second phase domain matrix.

A frequency slope of each of the plurality of pre-chirps may be different from a frequency slope of each of the plurality of main chirps.

In accordance with another aspect of the present disclosure, a method of controlling an apparatus including an antenna array installed on a vehicle includes providing a pre-chirp signal including a plurality of pre-chirps and a main chirp signal including a plurality of main chirps to the antenna array, sequentially transmitting, by the antenna array, radio waves corresponding to the pre-chirp signal and radio waves corresponding to the main chirp signal, and receiving, by the antenna array, radio waves reflected from an object around the vehicle, The number of pre-chirps may be smaller than the number of main chirps.

The method may further include acquiring a first reflection chirp signal corresponding to the radio waves reflected from the object around the vehicle while transmitting the pre-chirp signal, mixing the pre-chirp signal with the first reflection chirp signal, and acquiring a first intermediate frequency signal in which the pre-chirp signal and the first reflection chirp signal are mixed.

The method may further include providing object data including information on a distance to the object and a moving speed of the object based on the first intermediate frequency signal.

The method may further include providing a bin mask corresponding to at least one bin not including data corresponding to the distance to the object.

The method may further include acquiring a second reflection chirp signal corresponding to the radio waves reflected from the object around the vehicle while transmitting the main chirp signal, mixing the main chirp signal with the second reflection chirp signal, and acquiring a second intermediate frequency signal in which the main chirp signal and the second reflection chirp signal are mixed.

The method may further include processing the second intermediate frequency signal, filtering the processed signal using the bin mask, and providing the object data including the information on the distance to the object and the moving speed of the object based on the filtered signal.

DETAILED DESCRIPTION OF EMBODIMENTS

The following detailed description is provided to assist the reader in gaining a comprehensive understanding of the methods, apparatuses, and/or systems described herein. Accordingly, various changes, modifications, and equivalents of the methods, apparatuses, and/or systems described herein will be suggested to those of ordinary skill in the art. The progression of processing operations described is an example; however, the sequence of and/or operations is not limited to that set forth herein and may be changed as is known in the art, with the exception of operations necessarily occurring in a particular order. In addition, respective descriptions of well-known functions and constructions may be omitted for increased clarity and conciseness.

Additionally, exemplary embodiments will now be described more fully hereinafter with reference to the accompanying drawings. The exemplary embodiments may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. These embodiments are provided so that this disclosure will be thorough and complete and will fully convey the exemplary embodiments to those of ordinary skill in the art. Like numerals denote like elements throughout.

It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. As used herein, the term “and/or,” includes any and all combinations of one or more of the associated listed items.

The expression, “at least one of a, b, and c,” should be understood as including only a, only b, only c, both a and b, both a and c, both b and c, or all of a, b, and c.

FIG.1is a block diagram for illustrating a configuration of a vehicle according to an embodiment of the present disclosure.FIG.2is a conceptual view for illustrating examples of multiple fields of views of a camera and a radar included in an apparatus for driver assistance according to an embodiment of the present disclosure.

As illustrated inFIG.1, a vehicle1includes a driving device20, a braking device30, a steering device40, and an apparatus100for driver assistance. The driving device20, the braking device30, the steering device40, and/or the apparatus100for driver assistance may communicate with one another via a vehicle communication network. For example, the electric devices20,30,40, and100included in the vehicle1may transmit or receive data via Ethernet, media oriented systems transport (MOST), Flexray, controller area network (CAN), local interconnect network (LIN), or the like.

The driving device20may move the vehicle1and include, for example, an engine, an engine management system (EMS), a transmission, and a transmission control unit (TCU). The engine may generate a power for the vehicle1to drive or travel, and the EMS may control the engine in response to a driver's acceleration intention through an accelerator pedal or a request or command of the apparatus100for driver assistance. The transmission may transmit the power generated by the engine to wheels for deceleration, and the TCU may control the transmission in response to a driver's transmission instruction through a transmission lever and/or a request or command of the apparatus100for driver assistance.

The braking device30may slow down or stop the vehicle1by applying brake to wheels and include, for example, a brake caliper and a brake control module (EBCM). The brake caliper may decelerate the vehicle1or stop the vehicle1using friction with a brake disc, and the EBCM may control the brake caliper in response to the driver's braking intention through a brake pedal and/or a request or command of the apparatus100for driver assistance. For example, the EBCM may receive a deceleration request or command including a deceleration from the apparatus100for driver assistance and electrically or hydraulically control the brake caliper so that the vehicle1decelerates depending on the requested deceleration.

The steering device40may include an electronic power steering control module (EPS). The steering device40may change a traveling direction of the vehicle1, and the EPS may assist a driver's operation of the steering device40so that the driver may easily manipulate a steering wheel according to the driver's steering intention through the steering wheel. In addition, the EPS may control the steering device40in response to a request or command of the apparatus100for driver assistance. For example, the EPS may receive a steering request or command including a steering torque and/or direction from the apparatus100for driver assistance and control the steering device40to steer the vehicle1depending on the requested steering torque.

In addition, the apparatus100for driver assistance may communicate with the driving device20, the braking device30, and the steering device40via the vehicle communication network.

The apparatus100for driver assistance may provide various functions for safety to the driver. For example, the apparatus100for driver assistance may provide lane departure warning (LDW), lane keeping assist (LKA), high beam assist (HBA), autonomous emergency braking (AEB), traffic sign recognition (TSR), adaptive cruise control (ACC), blind spot detection (BSD), and the like, but not limited thereto.

The apparatus100for driver assistance may include, for example, but not limited to, one or more of a camera110, a radar120, and a controller140. One or more of the camera110, the radar120, and the controller140may not be an essential component of the apparatus100for driver assistance. For example, at least one of the camera110, the radar120, or the controller140may be omitted from the apparatus100for driver assistance, and a detector (e.g., light detection and ranging (LiDAR)) capable of detecting objects around the vehicle1may also be added to the apparatus100for driver assistance.

The camera110may capture surroundings of the vehicle1and acquire image data of the surroundings of the vehicle1. For example, as illustrated inFIG.2, the camera110may be installed on a front windshield of the vehicle1and may have a field of view110aoutside the vehicle1.

The camera110may include a plurality of lenses and an image sensor111. For instance, the image sensor111may include a plurality of photodiodes for converting light into electrical signals, and the plurality of photodiodes may be arranged in the form of a two-dimensional matrix. The image sensor111may output image data including images of one or more objects around the vehicle1.

The camera110may include an image processor112configured to process the image data. For example, the image processor112may process the image data to identify relative positions (e.g., distances from the vehicle1and angles with respect to the traveling direction of the vehicle1) and classification (e.g., whether objects are other vehicles, pedestrians, cyclists, or the like) of objects of the vehicle1. The image processor112may output first object data based on the processing of the image data. The first object data may include information on other vehicles, pedestrians, cyclists, or lane line markers (e.g. markers for distinguishing lanes) positioned around the vehicle1.

The camera110may be electrically or communicationally connected to the controller140. For example, the camera110may be connected to the controller140via the vehicle communication network or connected to the controller140via a hard wire or wireless communication. The camera110may transmit the first object data around the vehicle1to the controller140.

The radar120may transmit transmission radio waves to the outside of the vehicle1and detect external objects around the vehicle1based on reflected radio waves reflected from the external objects. For example, as illustrated inFIG.2, the radar120may be installed on a grille or bumper of the vehicle1and may have a sensing area or detection area120aoutside the vehicle1.

The radar120may include an antenna array121including a transmission antenna TX (or a transmission antenna array) for radiating transmission radio waves to the surroundings of the vehicle1and a reception antenna RX (or a reception antenna array) for receiving reflected radio waves reflected from objects. The radar120may acquire radar data from the transmission radio waves transmitted by the transmission antenna TX and the reflected radio waves received by the reception antenna RX.

The radar120may include a signal processor122configured to process the radar data. The signal processor122may identify relative positions and relative velocities of the objects based on the radar data. The signal processor122may output second object data based on the processing of the radar data. The second object data may include position information (e.g., distance information) and/or speed information of the objects of the vehicle1.

The radar120may be connected to the controller140via, for example, the vehicle communication network or the hard wire, and may transmit the radar data to the controller140.

The controller140may be electrically or communicationally connected to the camera110and/or the radar120. In addition, the controller140may be connected to the driving device20, the braking device30, and the steering device40via the vehicle communication network.

The controller140may process the first object data of the camera110and/or the second object data of the radar120and provide control signals to the driving device20, the braking device30, and/or the steering device40.

The controller140may include a memory142and a processor141.

The memory142may store programs, commands, instructions and/or data for processing the first object data of the camera110and/or the second object data of the radar120. In addition, the memory142may store programs, commands, instructions and/or data for generating driving, braking, and steering signals.

The memory142may permanently or temporarily store the first object data received from the camera110and/or the second object data received from the radar120and permanently or temporarily store the results of processing the first object data and/or the second object data by the processor141.

The memory142may include not only volatile memories such as a static random access memory (SRAM) and a dynamic RAM (DRAM) but also non-volatile memories such as a flash memory, a read only memory (ROM), and an erasable programmable ROM (EPROM).

The processor141may process the first object data of the camera110and/or the second object data of the radar120. Based on the processing of the object data, the processor141may provide or generate a control signal, for example, but not limited to the driving signal, the braking signal, and/or the steering signal for controlling the driving device20, the braking device30, and/or the steering device40, respectively. For example, the processor141may include a micro controller unit (MCU) configured to process the first object data of the camera110and/or the second object data of the radar120and generate the driving, braking, and steering signals.

The processor141may perform sensor fusion for detecting nearby objects of the vehicle1by fusing or combining the first object data of the camera110and the second object data of the radar120. The processor141may output “object data” by performing the sensor fusion. For example, the processor141may match objects identified based on the second object data of the radar120with objects identified based on the first object data of the camera110and determine or identify classification, relative positions, and relative velocities of the nearby objects of the vehicle1based on the matched objects.

The processor141may calculate or evaluate risk of a collision between the vehicle1and at least one of the nearby objects based on the relative positions and relative velocities of the nearby objects of the vehicle1. For example, the processor141may calculate a time to collision (TTC) (or a distance to collision (DTC)) between the vehicle1and the nearby object based on the position (distance) and relative speed of the nearby object of the vehicle1and evaluate the risk of collision between the vehicle1and the nearby object based on the TTC (or DTC). The processor141may determine that the shorter the TTC, the higher the risk of collision.

The processor141may select a target object among the nearby objects of the vehicle1based on the risk of collision. For example, the processor141may select the target object based on the TTCs between the vehicle1and the nearby objects.

The processor141may generate a control signal such as the driving signal, the braking signal, or the steering signal based on the risk of a collision with the target object. For example, the processor141may warn a driver of a collision or transmit the braking signal to the braking device30based on a comparison between a reference time and the TTC between the vehicle1and the target object. In addition, the processor141may transmit the steering signal to the steering device40in order to avoid the collision with the target object based on the comparison between a reference time and the TTC between the vehicle1and the target object.

Hereinafter, configurations and operations of the radar120and the signal processor122will be described in more detail.

FIG.3is graphs for illustrating an example of radio waves transmitted by an apparatus for driver assistance according to an embodiment of the present disclosure.

The radar120may include, for example, a frequency-modulated continuous-wave (FMCW) type radar for transmitting a series of linear chirps.

The FMCW type radar120may transmit the chirps through the antenna array121. The chirp may include a signal (e.g. a sine wave or a sinusoidal wave) in which frequency increases or decreases with time.

For example, as illustrated inFIG.3, a linear chirp may include a sine wave or a sinusoidal wave in which frequency linearly increases or decreases with time.

A frequency of the linear chirp illustrated inFIG.3can be expressed as Equation 1.

Here, f0denotes a start frequency at a time point to, B denotes a modulation width (e.g., bandwidth) of a frequency, and Tcdenotes a frequency modulation time of the linear chirp. S denotes a frequency change rate or a frequency slope.

In addition, since a derivative of a time with respect to a phase ϕ is an angular frequency, a function corresponding to a phase of a transmission signal may be an integral of a frequency function. Therefore, a change in the phase ϕ of the chirp can be expressed as Equation 2.

Here, ϕ denotes a phase of the linear chirp, and f(t) denotes a frequency of the linear chirp.

Using Equation 2, the phase ϕ of the linear chirp can be expressed as Equation 3.

Here, ϕ denotes the phase of the linear chirp, and f(t) denotes the frequency of the linear chirp. t0denotes a start time, f0denotes a start frequency, and ϕ0denotes an initial phase. In addition, B denotes a bandwidth of the linear chirp, and Tcdenotes a modulation time of the linear chirp.

Using Equation 3, the phase ϕ with respect to the time can be expressed as Equation 4.

Here, ycdenotes a linear chirp function, Acdenotes an amplitude of the linear chirp, and m denotes an mthchirp.

As illustrated inFIG.3, the radar120may transmit the linear chirp expressed as Equation 4.

A transmission chirp transmitted from the radar120may be mixed with a reception chirp reflected from an object. The reception chirp may be attenuated and delayed while being reflected from the object and propagated.

Due to such a time delay, a frequency of the reception chirp may be different from a frequency of the transmission chirp. Since the frequency of the transmission chirp linearly varies over time, the frequency of the reception chirp delayed during reflection may be different from the frequency of the transmission chirp. In addition, a difference between the frequency of the transmission chirp and the frequency of the reception chirp may be proportional to a distance between the vehicle1and a reflective object.

The signal processor122of the radar120may identify the distance between the vehicle1and the reflective object based on the difference between the frequency of the transmission chirp and the frequency of the reception chirp.

FIG.4is a block diagram of a signal processing circuit included in an apparatus for driver assistance according to an embodiment of the present disclosure.

The radar120may further include a signal processing circuit200configured to process an analog signal received by the antenna array121.

The signal processing circuit200may acquire an intermediate frequency signal representing the difference between the frequency of the transmission chirp and the frequency of the reception chirp based on the processing of the analog signal. The signal processing circuit200may convert the acquired intermediate frequency signal into a digital signal and provide the digitalized intermediate frequency signal to the signal processor122.

The signal processing circuit200may include a synthesizer210, a power amplifier (PA)220, a low noise amplifier (LNA)230, a frequency mixer240, and/or an analog-to-digital converter (ADC)250. At least one of the synthesizer210, the power amplifier220, the low noise amplifier230, the frequency mixer240, and the ADC250may not be essential components of the signal processing circuit200, and at least one thereof may be omitted.

The synthesizer210may generate a linear chirp signal in which a plurality of linear chirps are consecutive. The chirp signal generated by the synthesizer210can be expressed as the above-described Equation 4.

The power amplifier220may amplify the chirp signal generated by the synthesizer210.

The amplified chirp signal may be transmitted by the transmission antenna TX (or the transmission antenna array) of the antenna array121. In addition, the reception antenna RX (or the reception antenna array) of the antenna array121may receive the chirp signal reflected from the object.

The low noise amplifier230may amplify the chirp signal received by the reception antenna RX.

The frequency mixer240may mix the transmission chip signal (e.g. the chirp signal generated by the synthesizer210) with the reception chirp signal (e.g. the chirp signal received by the reception antenna RX). The frequency mixer240may output an intermediate frequency signal (IF) by mixing the transmission chirp signal with the reception chirp signal. The intermediate frequency signal output from the frequency mixer240may include information on the object.

The ADC250may convert the intermediate frequency signal output from the frequency mixer240into a digital signal and provide the converted digital signal to the signal processor122.

The signal processor122may receive the digital signal representing the intermediate frequency signal from the ADC250and process the received digital signal.

The signal processor122may identify a distance to the reflective object from the vehicle1and a moving speed of the reflective object based on the processing of the digital signal.

FIG.5is a conceptual diagram and graphs for illustrating an example of a transmission chirp signal and a reception chirp signal of an apparatus for driver assistance according to an embodiment of the present disclosure.

Since a frequency of a signal (e.g. an intermediate frequency signal) mixed by the frequency mixer240is a frequency corresponding to a difference between instantaneous frequencies and the reception chirp signal is the delayed signal of the transmission chirp signal generated by the synthesizer210, the intermediate frequency signal may include a frequency component proportional to the delay of the reception chirp signal.

For example, as illustrated inFIGS.5(a) and5(b), a transmission chirp signal TS transmitted from the antenna array121may be reflected from a first object O1and a second object O2. The antenna array121may receive a first reception chirp signal RS1reflected from the first object O1and a second reception chirp signal RS2received by the second object O2.

InFIG.5(c), a frequency of a mixed signal of the transmission chirp signal TS and the first reception chirp signal RS1may be a first intermediate frequency fb1, and a frequency of a mixed signal of the transmission chirp signal TS and the second reception chirp signal RS2may be a second intermediate frequency fb2.

The frequency of the mixed signal may correspond to a delay between the transmission chirp signal and the reception chirp signal. Specifically, the frequency of the mixed signal can be expressed as Equation 5.

Here, fbdenotes a frequency of the mixed signal, r denotes a distance to the reflective object, c denotes a speed of light, and S denotes a frequency slope of the transmission chirp signal. In addition, Tcdenotes a modulation time, and B denotes a bandwidth of the transmission chirp signal.

The delay between the transmission chirp signal and the reception chirp signal may be equal to a round-trip delay time to the object. In addition, a difference between the frequency of the transmission chirp signal and the frequency of the reception chirp signal may correspond to the round-trip delay time.

The distance r to the object can be expressed as Equation 6.

Here, r denotes the distance to the reflective object, c denotes the speed of light, and S denotes the frequency slope of the transmission chirp signal. Tcdenotes the modulation time, B denotes the bandwidth of the transmission chirp signal, and fbdenotes the intermediate frequency of the signal mixed by the frequency mixer240.

In addition, initial phases of all components of the intermediate frequency signal may be a difference between a phase of the transmission chirp signal and a phase of the reception chirp signal at the start of the intermediate frequency signal.

The radar120may consecutively transmit a plurality of chirp signals at uniform intervals in order to identify a moving speed of a moving object.

While the object is moving, a distance measurement through the round-trip delay of the chirp signal is affected by compression or elongation of a signal known as the Doppler effect.

Spatial displacement of the object may occur due to the movement of the object while the plurality of chirp signals are consecutively transmitted.

The spatial displacement of the object may affect both the frequency and phase of the intermediate frequency signal by the plurality of chirp signals. The spatial displacement of the object may lead to a change in the round-trip delay of the chirp signal. The spatial displacement of the object does not affect the initial phase of the transmission chirp signal but affects a current phase of the reception chirp signal, and thus may affect the phase of the intermediate frequency signal.

A phase difference of the intermediate frequency signal can be expressed as Equation 7.

Here, Δϕ denotes a phase difference of the intermediate frequency signal, f0denotes a start frequency of the chirp signal, λ0denotes a wavelength of the chirp signal, Δt denotes a change in the round-trip delay of the chirp signal, and Δd denotes a change in the round-trip distance, that is, the spatial displacement of the object.

When the object moves by Δd for the modulation time Tc, the speed of the moving object can be expressed as Equation 8.

Here, v denotes a speed of the moving object, λ0denotes the wavelength of the chirp signal, Tcdenotes the modulation time, and Δϕ denotes the phase difference of the intermediate frequency signal.

FIG.6is a view for illustrating an example of processing an intermediate frequency signal of an apparatus for driver assistance according to an embodiment of the present disclosure.

The signal processor122may process the digitized intermediate frequency signal using fast Fourier transform (FFT). The signal processor122may determine or identify the intermediate frequency fbof the intermediate frequency signal and the phase difference Δϕ of the intermediate frequency signal using the FFT. In addition, the signal processor122may identify the distance to the object based on the intermediate frequency fbof the intermediate frequency signal and the moving speed of the object based on the phase difference Δϕ of the intermediate frequency signal.

The radar120may transmit the chirp signal including the plurality of chirps in order to identify the distance to the object and the moving speed of the object. For example, as illustrated inFIG.6, the radar120may transmit a signal including M chirps.

The ADC250may sample the intermediate frequency signal N times while each chirp is transmitted, and convert the sampled analog signal into a digital signal.

The signal processor122may transform the intermediate frequency signal digitized by the ADC250into a frequency domain signal through the FFT. Specifically, the signal processor122may transform an intermediate frequency signal corresponding to one chirp into a frequency domain signal through the FFT.

For example, as illustrated inFIG.6, the signal processor122may transform an intermediate frequency signal corresponding to each of the M chirps into a frequency domain signal through the FFT. When acquiring N pieces of sampling data of the intermediate frequency signal corresponding to one chirp, the signal processor122may transform the acquired sampling data into the frequency domain signal through the FFT. Therefore, the signal processor122may store only the N pieces of sampling data, and less memory space can be used for storing the sampling data.

Hereinafter, the transforming of the intermediate frequency signal corresponding to each of the M chirps into the frequency domain signal through the FFT is referred to as a “range FFT.”

The signal processor122may acquire a frequency domain matrix300having peaks at intermediate frequencies fb1and fb2corresponding to the distances to the reflective objects as illustrated inFIG.5by performing the range FFT on the intermediate frequency signal corresponding to each of the M chirps. As described above, due to the frequency difference between the transmission chirp signal and the reception chirp signal caused by the delay of the reception chirp signal, the intermediate frequency signal having the peaks at the intermediate frequencies fb1and fb2may be acquired, and the frequency domain matrix300having the peaks at the intermediate frequencies fb1and fb2may be acquired.

Then, as illustrated inFIG.6, the signal processor122may transform data of the frequency domain matrix300, which has been acquired after performing the range FFT, through the FFT. Specifically, the signal processor122may transform a series of data, which correspond to the same frequency in the frequency domain matrix300, through the FFT.

Hereinafter, the transforming of the series of data corresponding to the same frequency through the FFT is referred to as a “Doppler FFT.”

The signal processor122may acquire a phase domain matrix400having a peak at the phase difference Δϕ corresponding to the moving speed of the reflective object as illustrated inFIG.6by performing the Doppler FFT. As described above, the phase difference Δϕ may occur between the M reception chirp signals due to the movement of the object, and the phase domain matrix400having the peak at each frequency corresponding to the phase difference Δϕ may be acquired by the Doppler FFT performed on the frequency domain matrix300.

The signal processor122may acquire the frequency domain matrix300by performing the range FFT on the intermediate frequency signal generated by the frequency mixing of the transmission chirp signal and the reception chirp signal. In addition, the signal processor122may acquire the phase domain matrix400by performing the Doppler FFT on the frequency domain matrix300.

As described above, the range FFT may be performed on the sampling data sampled at the same chirp, and the Doppler FFT may be performed on the series of data corresponding to the same frequency. For example, as illustrated inFIG.6, the range FFT may be performed on data in the same column, and the Doppler FFT may be performed on data in the same row.

Hereinafter, the performing of the range FFT on the data in the same column and the performing of the Doppler FFT on the data in the same row are collectively referred to as a “2-dimension FFT” The signal processor122may sample the N intermediate frequency signals and store the sampled signals to perform the range FFT. At this time, since the range FFT is performed on N sampling data corresponding to one chirp, a memory may store the N sampling data.

On the other hand, since the Doppler FFT is performed on the series of data corresponding to the same frequency of the frequency domain matrix300generated by performing the range FFT, N frequency data are required for all M chirps to perform the Doppler FFT. Therefore, a memory capable of storing M×N frequency data may be used to perform the Doppler FFT.

The radar120may transmit a pre-chirp signal to use less memory space for storing the frequency data.

FIG.7is a graph for illustrating an example of a transmission chirp signal of an apparatus for driver assistance according to an embodiment of the present disclosure.FIG.8is a conceptual diagram for illustrating an example for processing an intermediate frequency signal corresponding to a pre-chirp signal of an apparatus for driver assistance according to an embodiment of the present disclosure.FIG.9is a conceptual diagram for illustrating an example of processing an intermediate frequency signal corresponding to a main chirp signal of an apparatus for driver assistance according to an embodiment of the present disclosure.

As illustrated inFIG.7, the radar120may transmit a pre-chirp signal PCS and a main chirp signal MCS. For example, the signal processing circuit200may generate or provide the pre-chirp signal PCS and the main chirp signal MCS to the antenna array121, and the antenna array121may transmit radio waves corresponding to the pre-chirp signal PCS and radio waves corresponding to the main chirp signal MCS. Hereinafter, the radio waves corresponding to the pre-chirp signal PCS and the radio waves corresponding to the main chirp signal MCS may be referred to as “pre-chirp signal PCS” and “main chirp signal MCS,” respectively.

The pre-chirp signal PCS may include Mp consecutive pre-chirps PC, and the main chirp signal MCS may include Mm consecutive main chirps MC. The number of pre-chirps PC included in the pre-chirp signal PCS may be smaller than the number of main chirps MCs included in the main chirp signal MCS.

The radar120may transmit the pre-chirp signal PCS before transmitting the main chirp signal MCS.

While the pre-chirp signal PCS is transmitted, the signal processor122may acquire N pieces of sampling data on an intermediate frequency signal corresponding to each of the Mp pre-chirps PCs.

The signal processor122may perform the range FFT on N pieces of sampling data of an intermediate frequency signal corresponding to one pre-chirp PC. The signal processor122may acquire an Mp×N frequency domain matrix300by the range FFT.

The signal processor122may perform the Doppler FFT on data corresponding to the same frequency in the Mp×N frequency domain matrix300. The signal processor122may acquire an Mp×N phase domain matrix400by the Doppler FFT as illustrated inFIG.8.

The signal processor122may identify a distance to an object positioned within the sensing area of the radar120and a moving speed of the object based on peaks of the Mp×N phase domain matrix400.

As illustrated inFIG.8, the signal processor122may apply a constant false alarm rate detection (CFAR) algorithm or a local maximum algorithm to data corresponding to one pre-chirp of the Mp×N phase domain matrix400.

The signal processor122may identify a distance at which each of the objects detected by the CFAR algorithm or the local maximum algorithm is positioned. In addition, the signal processor122may identify a distance at which no object is present, that is, a row in which no object data is present in the Mp×N phase domain matrix400.

Each row of the frequency domain matrix300and each row of the phase domain matrix400may include a series of data corresponding to the same intermediate frequency. Therefore, the same row of the frequency domain matrix300and the same row of the phase domain matrix400may each represent the same distance.

Hereinafter, a series of data (e.g., each row in the matrix illustrated inFIG.8) representing the same distance in the frequency domain matrix300and the phase domain matrix400is referred to as “bin.”

The signal processor122may identify a bin in which no object data is present in the Mp×N phase domain matrix400. For example, the signal processor122may identify that no object data is present in a second bin bin2and a fifth bin bin5from the top of the phase domain matrix400illustrated inFIG.8.

The signal processor122may generate a bin mask500for ignoring, removing, missing, or filtering data of the second bin bin2and the fifth bin bin5in order to remove bins not including the object data.

The radar120may transmit the main chirp signal MCS after transmitting the pre-chirp signal PCS.

While the main chirp signal MCS is transmitted, the signal processor122may acquire N pieces of sampling data on an intermediate frequency signal corresponding to each of Mm main chirps MCs.

The signal processor122may perform the range FFT on N pieces of sampling data of an intermediate frequency signal corresponding to one main chirp MC.

While performing the range FFT, the signal processor122may ignore, remove, omit, or filter the data of the bins not including the object data using the bin mask500and store only data of bins including the object data.

For example, as illustrated inFIG.8, the signal processor122may include the bin mask500for ignoring, removing, or missing the second bin bin2and the fifth bin bin5. Since the signal processor122may apply the bin mask500to a series of data output by the range FFT, the data of the second bin bin2and the data of the fifth bin bin5among the data output by the range FFT may be ignored, removed, or missed as illustrated inFIG.9.

The signal processor122may acquire an Mm×K frequency domain matrix300by the range FFT. Here, “K” denotes the number of bins after being ignored, removed, or missed by the bin mask500. In addition, the number of bins K after being ignored, removed, or missed may be less than the number of pieces of sampling data N.

As described above, less memory space for storing the frequency domain matrix300can be used by ignoring, removing, or missing the data of the bins not including the object data.

In addition, the signal processor122may perform the Doppler FFT on data corresponding to the same frequency in the Mm×K frequency domain matrix300. The signal processor122may acquire an Mm×K phase domain matrix400by the Doppler FFT.

The signal processor122may identify a distance to an object positioned within the sensing area of the radar120and a moving speed of the object based on peaks of the Mm×K phase domain matrix400.

As described above, the radar120may consecutively transmit the pre-chirp signal PCS and the main chirp signal MCS. In this case, the number of chirps of the pre-chirp signal PCS may be less than the number of chirps of the main chirp signal MCS.

The radar120may identify the distance to the object positioned within the sensing area of the radar120and the moving speed of the object based on the intermediate frequency signal by the pre-chirp signal PCS. The radar120may identify the bins not including the object data in the phase domain matrix400based on the intermediate frequency signal by the pre-chirp signal PCS and generate or provide the bin mask500for ignoring, removing, or missing the data of the bins not including the object data.

The radar120may identify the distance to the object positioned within the sensing area of the radar120and the moving speed of the object based on the intermediate frequency signal by the main chirp signal MCS. While identifying the objects, the radar120may ignore, remove, or miss the bins not including the object data in a data matrix for processing the intermediate frequency signal using the bin mask500.

Therefore, the radar120can reduce the size of the data matrix for processing the intermediate frequency signal and also use less memory space for storing the data matrix. In addition, the resource and amount of calculation of the signal processor122for processing the data matrix can be reduced.

FIG.10is a conceptual diagram for illustrating an example for processing an intermediate frequency signal corresponding to a pre-chirp signal of an apparatus for driver assistance according to an embodiment of the present disclosure.

In the case of a moving object MO, peaks may appear at a specific distance and a specific speed after performing the 2-dimensional FFT.

On the other hand, the phase domain matrix400in which peaks corresponding to the same speed are listed according to distances by structures around a road may be acquired. For example, as illustrated inFIG.10, peaks corresponding to the same speed may be listed according to the distance by a stopped object SO. Therefore, the size of the phase domain matrix400cannot be reduced.

As described above, when the structures around the road are detected, a magnitude of the moving speed of the detected object may be the same as a traveling speed of the vehicle1. That is, in the phase domain matrix400, peaks corresponding to the same speed as the magnitude of the traveling speed of the vehicle1may be listed according to the distances.

As described above, when the peaks corresponding to the same speed as the magnitude of the traveling speed of the vehicle1are listed according to the distances in the phase domain matrix400, the radar120may generate the bin mask500without considering data of the stopped object SO. That is, the radar120may generate the bin mask500based on data of the moving object MO only, not the data of the stopped object SO.

Then, the radar120may correct the bin mask500based on the data of the stopped object SO (e.g., the peaks representing the same speed). That is, the radar120may correct the bin mask500based on the closest distance among the distances detected by the data of the stopped object SO.

For example, as illustrated inFIG.10, the radar120may generate the bin mask500for ignoring, removing, missing, or filtering data of a second bin bin2, a fourth bin bin4, and a fifth bin bin5based on the data of the moving object MO. Then, the radar120may determine that the data of the stopped object SO is present in the second bin bin2having the closest distance from the vehicle1based on the data of the stopped object SO. The radar120may generate the bin mask500for ignoring, removing, missing, or filtering data of the fourth bin bin4and the fifth bin bin5based on both the data of the moving object MO and the data of the stopped object SO.

Therefore, it is possible to prevent or suppress the detection of non-movable structures around the road from interfering with operation of reducing the size of the phase domain matrix400.

FIG.11is a graph for illustrating an example of a transmission chirp signal of an apparatus for driver assistance according to an embodiment of the present disclosure.

As illustrated inFIG.11, the radar120may sequentially transmit the pre-chirp signal PCS and the main chirp signal MCS.

The pre-chirp signal PCS may include Mp consecutive pre-chirps PCs, and the main chirp signal MCS may include Mm consecutive main chirps MCs. In this case, the number of pre-chirps PCs included in the pre-chirp signal PCS may be less than the number of main chirps MCs included in the main chirp signal MCS.

The Mp consecutive pre-chirps PCs of the pre-chirp signal PCS and the Mm consecutive main chirps MCs of the main chirp signal MCS are each transmitted at a predetermined pulse repetition interval PRI. In this case, the PRI at which the pre-chirps PCs are transmitted may be different from the PRI at which the main chirps MCs are transmitted. For example, the pre-chirps PCs may be transmitted at a first PRI, and the main chirps MCs may be transmitted at a second PRI which is different from the first PRI.

That is, a modulation time Tcof the pre-chirp PC may be different from a modulation time Tcof the main chirp MC. Therefore, a frequency slope S at which a frequency of the pre-chirp PC varies may be different from a frequency slope S at which a frequency of the main chirp MC varies.

As described above, since the first PRI of the pre-chirp PC is different from the second PRI of the main chirp MC, Doppler ambiguity can be resolved.

As is apparent from the above description, an apparatus for driver assistance including a radar and a method of controlling the same according to some embodiments of the present disclosure may reduce the amount of data stored in the memory and reduce the calculation of data performed by the processor.

Exemplary embodiments of the present disclosure have been described above. In the exemplary embodiments described above, some components may be implemented as a “module”. Here, the term ‘module’ means, but is not limited to, a software and/or hardware component, such as a Field Programmable Gate Array (FPGA) or Application Specific Integrated Circuit (ASIC), which performs certain tasks. A module may advantageously be configured to reside on the addressable storage medium and configured to execute on one or more processors.

Thus, a module may include, by way of example, components, such as software components, object-oriented software components, class components and task components, processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. The operations provided for in the components and modules may be combined into fewer components and modules or further separated into additional components and modules. In addition, the components and modules may be implemented such that they execute one or more CPUs in a device.

With that being said, and in addition to the above-described exemplary embodiments, embodiments can thus be implemented through computer readable code/instructions in/on a medium, e.g., a computer readable medium, to control at least one processing element to implement any above-described exemplary embodiment. The medium can correspond to any medium/media permitting the storing and/or transmission of the computer readable code.

The computer-readable code can be recorded on a medium or transmitted through the Internet. The medium may include Read Only Memory (ROM), Random Access Memory (RAM), Compact Disk-Read Only Memories (CD-ROMs), magnetic tapes, floppy disks, and optical recording medium. Also, the medium may be a non-transitory computer-readable medium. The media may also be a distributed network, so that the computer readable code is stored or transferred and executed in a distributed fashion. Still further, as only an example, the processing element could include at least one processor or at least one computer processor, and processing elements may be distributed and/or included in a single device.