Systems and methods for adaptive radar frame filtering

Abstract

To disclose a system and a method for adaptively filtering out representations of objects from radar frames captured by a radar device.SOLUTION: Maximum signal strength at zero velocity is obtained within a range bin that includes detection corresponding to objects in a range-doppler representation of a set of radar frames captured during a time period prior to the radar frame. The range-doppler representation of the radar frame is generated, and a direction vector representing a direction from a radar device to the object is determined. Radial relative velocity between the object and the radar device is then determined based on an obtained motion vector and the determined direction vector. The representation of the object from the radar frame is filtered out provided that the detection is located within a set interval, and the detection corresponding to the object is not filtered out from the radar frame provided that the detection is located outside the set interval.SELECTED DRAWING: Figure 1b

Description

[Technical Field]

[0001] The present invention relates to processing radar frames, and in particular to filtering out representations of objects from radar frames captured by a radar device. [Background technology]

[0002] When a radar device is mounted on a fixed support and used to monitor a scene, processing of each radar frame may be performed so that radar data related to stationary objects, such as the ground, buildings, and parked vehicles, may be removed from each radar frame. Such processing may be performed in applications where moving objects in a scene are of greater interest than stationary objects. Processing is fairly simple when the radar device is firmly attached to a fixed, rigid support, such as a wall. However, if the radar device is mounted on a fixed, non-rigid support, such as a non-rigid pole that may vibrate or swing back and forth, movement of the radar device may result, thereby causing relative motion between the stationary object and the moving radar device. Therefore, in such a scenario, radar data related to stationary objects may not be removed from the radar frame because the movement of the radar device causes the stationary object to no longer appear stationary.

[0003] Therefore, improvements in this context are desirable. Summary of the Invention

[0004] In view of the above, it is an object of the inventive concept to mitigate, alleviate or eliminate one or more of the above-identified deficiencies and drawbacks in the art, singly or in any combination.

[0005] According to a first aspect, a method is provided for adaptively filtering out representations of objects from radar frames captured by a radar device. Within a range bin containing a detection corresponding to the object in a range-Doppler representation of a set of radar frames captured by the radar device during a time period preceding the radar frame, a maximum signal strength at zero velocity is obtained, the time period including at least one period of oscillatory motion of the radar device relative to a fixed object in a scene monitored by the radar device. A motion vector representing a determined magnitude and direction of motion of the radar device due to the oscillatory motion of the radar device is obtained. Radar frames captured by the radar device having the determined magnitude and direction of motion are received, and a range-Doppler representation of the radar frame is generated. A direction vector representing a direction from the radar device to the object is determined, and a radial relative velocity between the object and the radar device is determined based on the obtained motion vector and the determined direction vector. For range bins in the range-Doppler representation containing a detection corresponding to the object, an interval is set around the determined radial relative velocity based on the determined radial relative velocity and the determined maximum signal strength. If the detection is located within the set interval, the representation of the object is filtered out from the radar frame, and if the detection is located outside the set interval, the detection corresponding to the object is not filtered out from the radar frame.

[0006] By determining a motion vector for the radar device at the time the radar frame was captured by the radar device and determining a direction vector from the radar to the object, a radial relative velocity between the object and the radar device at the time the radar frame was captured can be determined. The radial relative velocity is then used, along with a maximum signal strength, to determine an interval around the radial relative velocity within a range bin in the range-Doppler representation of the radar frame, the range bin containing the detection corresponding to the object. The interval is then used to determine whether the representation of the object is filtered out from the radar frame. By basing the interval on the determined radial relative velocity, stationary objects that appear to have a velocity different from zero in the range-Doppler representation of the radar frame due to oscillatory motion of the radar device can be identified as stationary objects and / or representations of such objects can be filtered out from the radar frame.

[0007] Because the spacing is based in part on the determined relative radial velocity at the time the radar frame was captured, the filtering is more adaptive to the current relative radial velocity. If a general increase in spacing is used, there is a higher risk that slowly moving objects will be filtered out of the radar frame.

[0008] In an embodiment, the action of obtaining a maximum signal strength at zero velocity includes receiving a set of radar frames captured by a radar device during a time period preceding the radar frames, the time period including at least one period of oscillatory motion of the radar device associated with a fixed object in a scene monitored by the radar device. Range-Doppler representations of the set of radar frames are generated, and detections corresponding to the objects are identified in each of the range-Doppler representations of the set of radar frames. Signal strengths at zero velocity of the detections corresponding to the objects in each range-Doppler representation are determined, and a maximum signal strength is determined as the maximum of the determined signal strengths.

[0009] According to a second aspect, a method is provided for adaptively filtering out representations of an object from a first radar frame of a plurality of radar frames captured by a radar device. For each radar frame of the plurality of radar frames, a maximum signal strength at zero velocity within a range bin containing a detection corresponding to the object is obtained in a range-Doppler representation of the set of radar frames captured by the radar device during a time period preceding the first radar frame, the time period including at least one period of oscillatory motion of the radar device relative to a fixed object in a scene monitored by the radar device. A motion vector representing a determined magnitude and direction of motion of the radar device due to the oscillatory motion of the radar device is obtained. A radar frame captured by the radar device having the determined magnitude and direction of motion is received, and a range-Doppler representation of the radar frame is generated. A direction vector representing a direction from the radar device to the detected object is determined, and a radial relative velocity between the object and the radar device is determined based on the determined motion vector and the determined direction vector. For a range bin in the range-Doppler representation that includes a detection corresponding to the object, an interval around the determined radial relative velocity is set based on the determined radial relative velocity and the determined maximum signal strength. A common interval is then calculated as an average of the set intervals for the multiple radar frames. If the detection corresponding to the object is located within the calculated common interval in the range bin of the range-Doppler representation of the first radar frame, the detection corresponding to the object is filtered out from the first radar frame. If the detection corresponding to the object is located outside the calculated common interval in the range bin of the range-Doppler representation of the first radar frame, the detection corresponding to the object is not filtered out from the first radar frame.

[0010] By the method according to the second aspect, as described in relation to the method according to the first aspect, stationary objects that appear to have a velocity different from zero velocity in the range-Doppler representation of the radar frame due to the vibrational motion of the radar device may be identified as stationary objects and / or representations of such objects may be filtered out from the radar frame.

[0011] Furthermore, by calculating the common interval as an average of the set intervals for multiple radar frames, robustness with respect to noise and errors can be increased.

[0012] In an embodiment, the vibratory motion of the radar device is due to the vibratory motion of a support structure to which the radar device is mounted.

[0013] According to a third aspect, there is provided a non-transitory computer-readable storage medium storing instructions for performing a method according to the first aspect or a method according to the second aspect when executed by a device having processing capability.

[0014] According to a fourth aspect, a device for adaptively filtering out representations of objects from radar frames captured by a radar device is provided. The device includes circuitry configured to perform a first acquisition function, a second acquisition function, a receiving function, a generating function, a first determination function, a second determination function, a setting function, and a filtering function. The first acquisition function is configured to acquire a maximum signal strength at zero velocity within a range bin containing a detection corresponding to the object in a range-Doppler representation of a set of radar frames captured by the radar device during a time period preceding the radar frame, the time period including at least one period of oscillatory motion of the radar device relative to a fixed object in a scene monitored by the radar device. The second acquisition function is configured to acquire a motion vector representing a determined magnitude and direction of motion of the radar device due to the oscillatory motion of the radar device. The receiving function is configured to receive radar frames captured by the radar device having the determined magnitude and direction of motion. The generating function is configured to generate a range-Doppler representation of the radar frame. The first determination function is configured to determine a direction vector representing a direction from the radar device to the object. The second determining function is configured to determine a radial relative velocity between the object and the radar device based on the determined motion vector and the determined direction vector. The setting function is configured to set an interval around the determined radial relative velocity based on the determined radial relative velocity and the determined maximum signal strength for a range bin in the range-Doppler representation that includes a detection corresponding to the object. The filtering function is configured to filter out a representation of the object from the first radar frame on the condition that the detection corresponding to the object is located within the set interval, and to refrain from filtering out a representation of the object from the first radar frame on the condition that the detection corresponding to the object is located outside the set interval.

[0015] The above-mentioned optional additional features of the method according to the first aspect also apply to the device according to the fourth aspect, when applicable. To avoid repetition, reference is made to the above.

[0016] According to a fifth aspect, a device is provided for adaptively filtering out representations of objects from a first radar frame of a plurality of radar frames captured by a radar device. The device includes circuitry configured to perform, for each radar frame of the plurality of radar frames, a first acquisition function, a second acquisition function, a receiving function, a generating function, a first determining function, a second determining function, and a setting function. The first acquisition function is configured to acquire a maximum signal strength at zero velocity within a range bin containing a detection corresponding to the object in a range-Doppler representation of a set of radar frames captured by the radar device during a time period preceding the radar frame, the time period including at least one period of oscillatory motion of the radar device relative to a fixed object in a scene monitored by the radar device. The second acquisition function is configured to acquire a motion vector representing a determined magnitude and direction of motion of the radar device due to the oscillatory motion of the radar device. The receiving function is configured to receive radar frames captured by the radar device having the determined magnitude and direction of motion. The generating function is configured to generate a range-Doppler representation of the radar frame. The first determining function is configured to determine a direction vector representing a direction from the radar device to the object. The second determining function is configured to determine a radial relative velocity between the object and the radar device based on the determined motion vector and the determined direction vector. The setting function is configured to set an interval around the determined radial relative velocity based on the determined radial relative velocity and the determined maximum signal strength for a range bin in the range-Doppler representation that includes a detection corresponding to the object. The circuit is further configured to perform a calculating function and a filtering function. The calculating function is configured to calculate a common interval as an average of the set intervals for multiple radar frames.The filtering function is configured to filter out representations of objects from the first radar frame on the condition that detections corresponding to the objects are located within a common interval within range bins of the range-Doppler representation of the first radar frame, and to refrain from filtering out representations of objects from the first radar frame on the condition that detections corresponding to the objects are located outside the common interval within range bins of the range-Doppler representation of the first radar frame.

[0017] In an embodiment, the vibratory motion of the radar device is due to the vibratory motion of a support structure to which the radar device is mounted.

[0018] Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the scope of the invention will become apparent to those skilled in the art from this detailed description.

[0019] Thus, it should be understood that the invention is not limited to the particular component parts of the described devices or actions of the described methods, as the described devices and methods may vary. It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not limiting. It should be noted that, as used in this specification and the appended claims, the articles "a," "an," "the," and "said" are intended to mean that there are one or more of an element, unless the context clearly dictates otherwise. Thus, for example, reference to "a unit" or "the unit" may include several devices, etc. Furthermore, the words "comprising," "including," "containing," and similar expressions do not exclude other elements or steps.

[0020] These and other aspects of the present invention will now be described in more detail with reference to the accompanying drawings, which should not be considered limiting but are used for purposes of explanation and understanding. [Brief explanation of the drawings]

[0021] [Figure 1a] 1 is a flowchart relating to an embodiment of a method for adaptively filtering out representations of objects from radar frames captured by a radar device. [Figure 1b] 1 is a flowchart relating to an embodiment of a method for adaptively filtering out representations of objects from radar frames captured by a radar device. [Figure 2a] 1 is a flowchart relating to an embodiment of a method for adaptively filtering out representations of objects from a first radar frame of a plurality of radar frames captured by a radar device. [Figure 2b] 1 is a flowchart relating to an embodiment of a method for adaptively filtering out representations of objects from a first radar frame of a plurality of radar frames captured by a radar device. [Figure 3] FIG. 1 is a block diagram associated with an embodiment of a device for adaptively filtering out representations of objects from radar frames captured by a radar device. [Figure 4] FIG. 1 is a block diagram associated with an embodiment of a device for adaptively filtering out representations of objects from a first radar frame of a plurality of radar frames captured by a radar device. DETAILED DESCRIPTION OF THE INVENTION

[0022] The present invention will now be described with reference to the accompanying drawings, in which presently preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

[0023] The present invention is applicable in scenarios where a radar device is fixed but not rigidly mounted, where there may be relative vibrational motion between stationary objects in a scene monitored by the radar device and the radar device itself due to vibrational motion of the radar device relative to fixed objects in the scene monitored by the radar device. This may occur, for example, when the radar device is mounted on a fixed, non-rigid support, such as a non-rigid pole, that may vibrate back and forth. Such vibration may occur, for example, due to wind or other physical impacts on the non-rigid support.

[0024] The radar device is of a type that allows the velocity of an object detected by the radar device to be determined. For example, the radar device may be a frequency modulated continuous wave (FMCW) radar device that uses a short beat signal (chirp) whose frequency varies with time, typically ramping up or down in frequency. As another example, the radar device may be a phase modulated continuous wave (PMCW) radar device.

[0025] The radar device may also be of a type that allows for determining a direction vector from the radar device to an object detected by the radar device. For example, the radar device may be a multiple-input multiple-output (MIMO) radar device.

[0026] Next, an embodiment of a method 100 for adaptively filtering out representations of objects from radar frames captured by a radar device will be described with reference to the flowchart in Figures 1a and 1b. Method 100 relates to adaptive filtering associated with one object. However, the principles of the method can be used for adaptive filtering associated with all objects in a radar frame, either sequentially or in parallel.

[0027] The method 100 includes obtaining S110 a maximum signal strength at zero velocity within a range bin containing a detection corresponding to an object in a range-Doppler representation of a set of radar frames captured by the radar device. The signal strength here relates to the signal strength of a reflected signal received at the radar device. The set of radar frames is captured during a time period preceding the radar frame, i.e., prior to the time the radar frame was captured. Furthermore, the time period is long enough to include at least one period of oscillatory motion of the radar device. This is to ensure that the maximum signal strength of the detection corresponding to the object is at or at least close to zero velocity in the range-Doppler representation of at least one radar frame of the set of radar frames. For example, if the period of oscillatory motion is 2 seconds and there are 10 radar frames per second, the set of radar frames should include at least 20 radar frames.

[0028] For an FMCW radar device, a range-Doppler representation can be generated by logically arranging the analog-to-digital conversion data corresponding to the downconverted chirp as columns of a matrix. An FFT within each column resolves objects within range from the radar device, such that each row is a range bin containing object detections within a range interval from the radar device. Meanwhile, an FFT along the rows resolves each row (range bin) in velocity associated with the radar device, such that each column contains object detections within a velocity interval associated with the radar device. The range-Doppler representation contains detections, the location of which, relative to the vertical y-axis, corresponds to objects in the scene at a different range from the radar device. The location of which, relative to the horizontal x-axis, corresponds to the radial velocity between the radar device and the object.

[0029] As described above, method 100 is described with respect to one object. In general, filtering may be performed with respect to all objects in the radar frames. The maximum signal strength at zero velocity within each range bin across the set of radar frames may then be obtained. The remaining steps S120-S194 of method 100 are then performed for each range bin in the radar frames based on the respective maximum signal strength. To reduce the number of range bins on which method 100 is performed, it may be limited to range bins containing objects that are likely to be stationary. This may be achieved by identifying all range bins with a maximum signal strength at zero velocity that exceeds a threshold value indicating detection corresponding to an object. The remaining steps of method 100 are then performed only for the identified range bins in the radar frames.

[0030] Action S110 of obtaining a maximum signal strength at zero velocity may include receiving a set of radar frames captured by a radar device during a time period preceding the radar frames. A range-Doppler representation of the set of radar frames is then generated. Then, within a range bin containing a detection corresponding to an object in each range-Doppler representation, a signal strength at zero velocity is determined, and a maximum signal strength is determined as the maximum of the determined signal strengths.

[0031] The method further includes obtaining S120 a motion vector representing a determined magnitude and direction of motion of the radar device relative to a fixed object in the scene monitored by the radar device. The relative motion between the radar device and the fixed object in the scene is due to the oscillatory motion of the radar device. Furthermore, because the motion of the radar device is oscillatory, the magnitude and direction of the radar device's motion changes over time. To this end, the magnitude and direction of the motion are determined when a radar frame is captured by the radar device. The motion vector may be obtained by receiving measurements from an accelerometer located in the radar device, the measurements being taken when the radar frame was captured. Alternatively, the motion vector may be obtained by determining relative velocities associated with a set of objects in the scene that are identified as stationary in the scene and have known locations associated with the radar device.

[0032] Method 100 further includes receiving radar frames captured by a radar device (S130) and generating a range-Doppler representation of the radar frames (S140). As described above, the radar device had a determined magnitude and direction of movement when the radar frames were captured. As described above, the range-Doppler representation includes detections, the positions of which relative to the vertical y-axis correspond to objects in the scene at a different range from the radar device. The positions of the detections relative to the horizontal x-axis correspond to the radial velocity between the radar device and the object. Due to the oscillatory motion, the radar device has a determined magnitude and direction of movement relative to a fixed object when the radar frames were captured. Therefore, detections corresponding to stationary objects in the scene will not be located at a location in the range-Doppler representation corresponding to zero velocity.

[0033] The method 100 further includes determining S150 a direction vector representing a direction from the radar device to the object, and determining S160 a radial relative velocity between the object and the radar device based on the acquired motion vector and the determined direction vector. The radar device may be a MIMO radar device. The radar device may further be an FMCW radar device or a PMCW radar device.

[0034] For range bins in the range-Doppler representation that contain a detection corresponding to the object, an interval is set around the determined relative radial velocity S170. The interval is set relative to the radar frame and is based on the determined relative radial velocity specific to the radar frame and the determined maximum signal strength. The interval is used to determine whether the representation of the object should be filtered out from the radar frame. Specifically, if the detection is located within the set interval C190, the representation of the object is filtered out from the radar frame S192. If the detection is located outside the set interval C190, the representation of the object is not filtered out from the radar frame S194. A detection located within the set interval means that the energy outside the interval is below the threshold for what is considered a detection. A detection located outside the set interval means that the energy outside the interval is above the threshold for what is considered a detection.

[0035] The interval being set around the determined relative radial velocity means that the interval starts below the determined relative radial velocity and ends above the determined relative radial velocity. For example, the interval may be symmetrical around the determined relative radial velocity, i.e., the determined relative radial velocity is in the middle of the interval.

[0036] The set interval around the determined radial relative velocity is used instead of the fixed guard interval around zero velocity set for all radar frames in the prior art. The interval is set based in part on the determined radial relative velocity, which in turn is determined based on the determined magnitude and direction of movement of the radar device at the time the radar frame was captured. Thus, the set interval for the radar frame is adapted to the determined magnitude and direction of movement of the radar device at the time the radar frame was captured. By adaptively setting the interval taking into account the determined maximum signal strength and the determined relative radial velocity, filtering is adapted so that representations of objects are filtered out of the radar frames even if detections within range bins would not be considered to correspond to stationary objects when prior art methods using a fixed guard interval are used. For example, the greater the radial relative velocity, the larger the interval may be set.

[0037] 2a and 2b show a flowchart relating to an embodiment of a method for adaptively filtering out representations of objects from a first radar frame of a plurality of radar frames captured by a radar device.

[0038] In method 200, the following actions are performed for each radar frame i of a plurality of radar frames consisting of n radar frames: an action S210 for obtaining a maximum signal strength, an action S220 for obtaining a motion vector, an action S230 for receiving a radar frame, an action S240 for generating a range-Doppler representation, an action S250 for determining a direction vector, an action S260 for determining a relative radial velocity, and an action S270 for setting a spacing. For details and options of these actions S210-S270, please refer to the details and options of the corresponding actions S110-S170 of method 100 described in relation to Figures 1a and 1b.

[0039] Thus, one interval for the range bins is set in association with each radar frame. A common interval for the range bins is then calculated as the average of the set intervals for the multiple radar frames (S280). The common interval is then used to determine whether the representation of the object should be filtered out from the first radar frame. The common interval is located around the radial relative velocity determined when the first radar frame was captured by the radar device (C290). Specifically, if the detection is located within the common interval (C290), the representation of the object is filtered out from the radar frame (S292). If the detection is located outside the common interval (C290), the representation of the object is not filtered out from the radar frame (S194).

[0040] For further details and options regarding the filtering actions S290-S294 of method 200, please refer to the details and options regarding the corresponding actions S190-S194 of method 100 described in relation to Figures 1a and 1b.

[0041] FIG. 3 shows a block diagram associated with an embodiment of a device 300 for adaptively filtering out representations of objects from radar frames captured by a radar device.

[0042] The device 300 includes a circuit 310. The circuit 310 is configured to perform the functions of the device 300. The circuit 310 may include a processor 312, such as a central processing unit (CPU), a graphical processing unit (GPU), a tensor processing unit (TPU), a microcontroller, or a microprocessor. The processor 312 is configured to execute program code. The program code may be configured to perform the functions of the device 300, for example.

[0043] The device 300 may further include a memory 320. The memory 320 may be one or more of a buffer, flash memory, a hard drive, removable media, volatile memory, nonvolatile memory, random access memory (RAM), or another suitable device. In a typical configuration, the memory 320 may include nonvolatile memory for long-term data storage and volatile memory that serves as device memory for the circuit 310. The memory 320 may exchange data with the circuit 310 via a data bus. Associated control lines and address buses may also exist between the memory 320 and the circuit 310.

[0044] The functionality of device 300 may be embodied in the form of executable logic routines (e.g., lines of code, software programs, etc.) stored in a non-transitory computer-readable medium (e.g., memory 320) of device 300 and executed by circuit 310 (e.g., using processor 312). Furthermore, the functionality of device 300 may be a standalone software application or may form part of a software application that performs additional tasks related to device 300. The described functions may be considered as methods that a processing unit, e.g., processor 312 of circuit 310, is configured to execute. Also, while the described functions may be implemented in software, such functionality may also be performed via dedicated hardware or firmware, or some combination of hardware, firmware, and / or software.

[0045] The circuit 310 is configured to perform a first obtaining function 331, a second obtaining function 332, a receiving function 333, a generating function 334, a first determining function 335, a second determining function 336, a setting function 337, and a filtering function 339.

[0046] The first acquisition function 331 is configured to acquire a maximum signal strength at zero velocity within a range bin containing a detection corresponding to an object in a range-Doppler representation of a set of radar frames captured by the radar device during a time period preceding the radar frame, the time period including at least one period of oscillatory motion of the radar device relative to a fixed object in a scene monitored by the radar device. The second acquisition function 332 is configured to acquire a motion vector representing a determined magnitude and direction of motion of the radar device due to the oscillatory motion of the radar device. The receiving function 333 is configured to receive radar frames captured by the radar device having the determined magnitude and direction of motion. The generating function 334 is configured to generate a range-Doppler representation of the radar frame. The first determination function 335 is configured to determine a direction vector representing a direction from the radar device to the object. The second determination function 336 is configured to determine a radial relative velocity between the object and the radar device based on the determined motion vector and the determined direction vector. The setting function 337 is configured to set an interval around the determined relative radial velocity based on the determined relative radial velocity and the determined maximum signal strength for a range bin in the range-Doppler representation that includes a detection corresponding to the object. The filtering function 339 is configured to filter out the representation of the object from the first radar frame if the detection corresponding to the object is located within the set interval, and to refrain from filtering out the representation of the object from the first radar frame if the detection corresponding to the object is located outside the set interval.

[0047] For further details and options regarding the functionality of device 300, please refer to the details and options regarding the actions of method 100 described in connection with Figures 1a and 1b.

[0048] FIG. 4 shows a block diagram associated with an embodiment of a device 400 for adaptively filtering out representations of objects from a first radar frame of a plurality of radar frames captured by a radar device.

[0049] The device 400 comprises a circuit 410. The circuit 410 is configured to perform the functions of the device 400. The circuit 410 may include a processor 412, such as a central processing unit (CPU), a graphical processing unit (GPU), a tensor processing unit (TPU), a microcontroller, or a microprocessor. The processor 112 is configured to execute program code. The program code may be configured to perform the functions of the device 400, for example.

[0050] The device 400 may further include a memory 420. The memory 420 may be one or more of a buffer, flash memory, a hard drive, removable media, volatile memory, non-volatile memory, random access memory (RAM), or another suitable device. In a typical configuration, the memory 420 may include non-volatile memory for long-term data storage and volatile memory that serves as device memory for the circuit 410. The memory 420 may exchange data with the circuit 410 via a data bus. Associated control lines and address buses may also exist between the memory 420 and the circuit 410.

[0051] The functionality of device 400 may be embodied in the form of executable logic routines (e.g., lines of code, software programs, etc.) stored in a non-transitory computer-readable medium (e.g., memory 420) of device 400 and executed by circuit 410 (e.g., using processor 412). Furthermore, the functionality of device 400 may be a standalone software application or may form part of a software application that performs additional tasks related to device 400. The described functions may be considered as methods that a processing unit, e.g., processor 412 of circuit 410, is configured to execute. Also, while the described functions may be implemented in software, such functionality may also be performed via dedicated hardware or firmware, or some combination of hardware, firmware, and / or software.

[0052] The circuit 410 is configured to perform, for each radar frame of the plurality of radar frames, a first obtaining function 431, a second obtaining function 432, a receiving function 433, a generating function 434, a first determining function 435, and a second determining function 436. The circuit 410 is further configured to perform a calculating function 438 and a filtering function 439.

[0053] The first acquisition function 431 is configured to acquire a maximum signal strength at zero velocity within a range bin containing a detection corresponding to an object in a range-Doppler representation of a set of radar frames captured by the radar device during a time period preceding the radar frame, the time period including at least one period of oscillatory motion of the radar device relative to a fixed object in a scene monitored by the radar device. The second acquisition function 432 is configured to acquire a motion vector representing a determined magnitude and direction of motion of the radar device due to the oscillatory motion of the radar device. The receiving function 433 is configured to receive radar frames captured by the radar device having the determined magnitude and direction of motion. The generating function 434 is configured to generate a range-Doppler representation of the radar frame. The first determination function 435 is configured to determine a direction vector representing a direction from the radar device to the object. The second determination function 436 is configured to determine a radial relative velocity between the object and the radar device based on the determined motion vector and the determined direction vector. The setting function 437 is configured to set an interval around the determined radial relative velocity based on the determined radial relative velocity and the determined maximum signal strength for a range bin in the range-Doppler representation that includes a detection corresponding to the object. The circuit is further configured to execute a calculation function 438 and a filtering function 439. The calculation function 438 is configured to calculate a common interval as an average of the set intervals for the plurality of radar frames. The filtering function 439 is configured to filter out the representation of the object from the first radar frame if the detection corresponding to the object is located within the common interval in the range bins of the range-Doppler representation of the first radar frame, and to refrain from filtering out the representation of the object from the first radar frame if the detection corresponding to the object is located outside the common interval in the range bins of the range-Doppler representation of the first radar frame.

[0054] For further details and options regarding the functionality of device 400, please refer to the details and options regarding the corresponding actions of method 100 described in connection with Figures 1a and 1b and method 200 described in connection with Figures 2a and 2b.

[0055] Those skilled in the art will appreciate that the present invention is not limited to the embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. Such modifications and variations can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.

Claims

1. 1. A method for adaptively filtering out representations of objects from radar frames captured by a radar device, the method comprising: obtaining a maximum signal strength at zero velocity within a range bin that includes a detection corresponding to the object in a range-Doppler representation of a set of radar frames captured by the radar device during a time period preceding the radar frame, the time period including at least one period of oscillatory motion of the radar device associated with a fixed object in a scene monitored by the radar device; obtaining a motion vector representing a determined magnitude and direction of motion of the radar device due to the vibrational motion of the radar device; receiving the radar frame captured by the radar device having the magnitude and direction of the acquired motion; generating a range-Doppler representation of the radar frame; determining a direction vector representing a direction from the radar device to the object; determining a relative radial velocity between the object and the radar device based on the acquired motion vector and the determined direction vector; for the range bin in the range-Doppler representation that includes the detection corresponding to the object, setting an interval around the determined relative radial velocity of the object based on the determined relative radial velocity and the determined maximum signal strength; filtering out representations of the object from the radar frames, provided that the detection corresponding to the object is located within the set interval; refraining from filtering out the representation of the object from the radar frame if the detection corresponding to the object is located outside the set interval; A method comprising:

2. The action of obtaining maximum signal strength at zero velocity is receiving a set of radar frames captured by the radar device during a time period preceding the radar frames, the time period including at least one period of the vibrational motion of the radar device associated with a fixed object in a scene monitored by the radar device; generating a range-Doppler representation of said set of radar frames; determining a signal strength at zero velocity within the range bin containing the detection corresponding to the object in each range Doppler representation; determining the maximum signal strength as the maximum of the determined signal strengths; The method of claim 1 , comprising:

3. 1. A method for adaptively filtering out representations of objects from a first radar frame of a plurality of radar frames captured by a radar device, the method comprising: For each radar frame of the plurality of radar frames, obtaining a maximum signal strength at zero velocity within a range bin containing a detection corresponding to the object in a range-Doppler representation of a set of radar frames captured by the radar device during a time period preceding the first radar frame, the time period including at least one period of oscillatory motion of the radar device associated with a fixed object in a scene monitored by the radar device; obtaining a motion vector representing a determined magnitude and direction of motion of the radar device due to the vibrational motion of the radar device; receiving the radar frames captured by the radar device having the determined magnitude and direction of motion; generating a range-Doppler representation of the radar frame; determining a direction vector representing a direction from the radar device to the detected object; determining a relative radial velocity between the object and the radar device based on the determined motion vector and the determined direction vector; for the range bin in the range-Doppler representation that includes the detection corresponding to the object, setting an interval around the determined relative radial velocity of the object based on the determined relative radial velocity and the determined maximum signal strength; calculating a common interval as an average of the set intervals for the plurality of radar frames; filtering out representations of the objects from the first radar frame, provided that the detections corresponding to the objects lie within the calculated common interval within the range bins of the range-Doppler representation of the first radar frame; refraining from filtering out the representation of the object from the first radar frame if the detection corresponding to the object is located outside the calculated common interval within the range bins of the range-Doppler representation of the first radar frame; A method comprising:

4. 4. The method of claim 1, wherein the vibrational movement of the radar device is due to vibrational movement of a support structure to which the radar device is mounted.

5. A non-transitory computer-readable storage medium having stored thereon instructions for performing the method of any one of claims 1 to 3 when executed by a device having processing capabilities.

6. 1. A device for adaptively filtering out representations of objects from radar frames captured by a radar device, the device comprising: a first acquisition function configured to acquire a maximum signal strength at zero velocity within a range bin that includes a detection corresponding to the object in a range-Doppler representation of a set of radar frames captured by the radar device during a time period preceding the radar frame, the time period including at least one period of oscillatory motion of the radar device associated with a fixed object in a scene monitored by the radar device; and a second acquisition function configured to acquire a motion vector representing the determined magnitude and direction of movement of the radar device due to the vibrational motion of the radar device; a receiving function configured to receive the radar frames captured by the radar device having the determined magnitude and direction of motion; a generation function configured to generate a range-Doppler representation of the radar frame; a first determination function configured to determine a direction vector representing a direction from the radar device to the object; a second determination function configured to determine a radial relative velocity between the object and the radar device based on the obtained motion vector and the determined direction vector; a setting function configured to set an interval around the determined relative radial velocity of the object based on the determined relative radial velocity and the determined maximum signal strength for the range bin in the range-Doppler representation that includes the detection corresponding to the object; filtering out representations of the object from the radar frames, provided that the detection corresponding to the object is located within the set interval; refraining from filtering out the representation of the object from the radar frame if the detection corresponding to the object is located outside the set interval; and a filtering function configured to 11. A device comprising: circuitry configured to perform

7. The first acquisition function: receiving a set of radar frames captured by the radar device during a time period preceding the radar frames, the time period including at least one period of the vibrational motion of the radar device associated with a fixed object in a scene monitored by the radar device; generating a range-Doppler representation of said set of radar frames; determining a signal strength at zero velocity within the range bin containing the detection corresponding to the object in each range Doppler representation; determining the maximum signal strength as the maximum of the determined signal strengths; The device of claim 6 configured to:

8. 1. A device for adaptively filtering out representations of objects from a first radar frame of a plurality of radar frames captured by a radar device, the device comprising: For each radar frame of the plurality of radar frames, a first acquisition function configured to acquire a maximum signal strength at zero velocity within a range bin that includes a detection corresponding to the object in a range-Doppler representation of a set of radar frames captured by the radar device during a time period preceding the first radar frame, the time period including at least one period of oscillatory motion of the radar device associated with a fixed object in a scene monitored by the radar device; and a second acquisition function configured to acquire a motion vector representing the determined magnitude and direction of movement of the radar device due to the vibrational motion of the radar device; a receiving function configured to receive the radar frames captured by the radar device having the determined magnitude and direction of motion; a generation function configured to generate a range-Doppler representation of the radar frame; a first determination function configured to determine a direction vector representing a direction from the radar device to the detected object; a second determination function configured to determine a radial relative velocity between the object and the radar device based on the determined motion vector and the determined direction vector; a setting function configured to set an interval around the determined relative radial velocity of the object based on the determined relative radial velocity and the determined maximum signal strength for the range bin in the range-Doppler representation including the detection including the object; a circuit configured to perform The circuit comprises: a calculation function configured to calculate a common interval as an average of the set intervals for the plurality of radar frames; filtering out representations of the objects from the first radar frames, provided that the detections corresponding to the objects lie within the calculated common interval within the range bins of the range-Doppler representation of the first radar; refraining from filtering out the representation of the object from the first radar frame if the detection corresponding to the object is located outside the calculated common interval within the range bins of the range-Doppler representation of the first radar; and a filtering function configured to further configured to perform device.

9. 9. A device according to claim 6, wherein the vibrational movement of the radar device is due to vibrational movement of a support structure to which the radar device is mounted.

Images