Radar sensor and method of operating a radar sensor

Abstract

A radar sensor has a radar transmitter controlled to operate in cycles, where each cycle comprises a sequence of frames, and each frame has an associated (fixed) duty cycle. Signals from a receiver of the radar sensor are interpreted to detect possible motion. A motion confirmation mode is then used to provide a more accurate motion signal. This duty cycle variation reduces power consumption without reducing detection range because it maintains a large duty cycle period (for wide-area detection).

Description

Technical Field

[0001] This invention relates to radar sensors, for example, for motion sensing, to detect the presence (and optionally motion characteristics) of an object or person. This detection is used for the automatic control of a device. Background Technology

[0002] The use of motion sensing in controlling devices is well-known. For example, motion sensing is used to control lighting systems, alarm systems, cameras and security systems, and smart home devices to provide presence detection.

[0003] The most common low-cost motion detectors use passive infrared (PIR) sensors. Radar sensors are more sensitive than PIR sensors and therefore offer improved performance. However, as active RF devices, radar sensors consume significantly more power than PIR sensors. This is a major limitation in using radar sensors instead of PIR sensors, especially for applications with tight power budgets (e.g., solar or battery solutions).

[0004] To achieve better efficiency, minimizing the power consumption of Internet of Things (IoT) devices, such as sensors in lighting products, is becoming increasingly important, not only during standby mode but also during normal operation. In the case of lighting systems, specific lighting efficiencies (lm / W) are required to meet certain energy labels (e.g., Class A).

[0005] As is well known, pulse operation can reduce the power consumption of radar sensors. Figure 1 The diagram illustrates a simplified description of the pulse operation of a radar sensor, plotting the operating voltage of the radar transmitter over time. The radar sensor (specifically its radio transmitter) operates in an intermittent, periodic mode. Within each cycle, which has a pulse repetition time of 10, the radar sensor operates for only a small portion of the entire cycle, i.e., the duration of the pulse width 12.

[0006] The duty cycle of the pulse operation is defined as the ratio of the pulse width 12 to the pulse repetition time 10 (e.g., as a percentage): Duty cycle = pulse width / pulse repetition time

[0007] The actual power consumption of a radar sensor depends on the duty cycle of the pulse operation: P 实际 =P cw ×Duty cycle

[0008] Pcw This is the power consumption of the radar sensor when it is operating in continuous mode.

[0009] Duty cycle not only determines power consumption but also radar signal quality, which in turn determines the maximum detection range of the radar sensor. Within a certain range, the lower the duty cycle, the smaller the detection range.

[0010] Existing solutions set the duty cycle based on the maximum detection range to ensure the radar sensor performs as required. Therefore, the reduction in radar power consumption is limited by its maximum detection range.

[0011] It is hoped that the power consumption of the radar sensor can be further reduced, while still ensuring the desired maximum detection range.

[0012] JP2006 / 226847 discloses a radar sensor that applies different duty cycles at different times.

[0013] US2020064445A1 relates to providing a smartphone-based energy-efficient radar processing and memory configuration for gesture detection. Different sequences are designed to configure the radar system in different ways. Each sequence is associated with a different power mode, and the power consumption within the radar system gradually increases from the first sequence to the last.

[0014] CN108684101A discloses a system including an object motion detection module, a microprocessor unit (MCU), and a brightness / color adjustable LED. The object motion detection module employs Doppler radar technology and generates a high-level signal when motion is detected. Upon receiving the high-level signal, the MCU adjusts the brightness and color of the LED by changing the duty cycle of a PWM signal and / or turning the PWM signal on / off.

[0015] US2023041835A1 discloses a method for exposure level estimation, which includes transmitting radar signals for object detection and communication signals for wireless communication operation. The method also includes identifying the position of an object relative to an electronic device based on the radar signals over a first duration, the first duration including previous times up to the current time. The method further includes determining a radio frequency (RF) exposure measurement associated with the object based on the object's position during the first duration. Furthermore, the method includes determining a power density budget for a second duration based on a comparison of the RF exposure measurement with an RF exposure threshold, the second duration including the current time up to a future time. The method also includes modifying the wireless communication operation during the second duration based on the power density budget. Summary of the Invention

[0016] This invention is defined by the claims.

[0017] According to one aspect of the present invention, a radar sensor is provided, the radar sensor comprising:

[0018] A radar transmitter, used to transmit radar pulses;

[0019] A radar receiver for receiving radar pulses reflected from the monitoring area of ​​a radar sensor; and

[0020] The controller is used to control the timing of the radar transmitter's operation.

[0021] The controller is configured during scan mode as follows:

[0022] - Control the radar transmitter to operate in cycles, where each cycle consists of a sequence of frames;

[0023] - During each frame, the control radar transmitter transmits a set of radar pulses with an associated duty cycle for that frame; and

[0024] - Interpret the signals from the radar receiver to detect possible motion.

[0025] The controller is configured to update the cyclic operation of the radar transmitter to provide a motion confirmation mode in response to the detection of possible motion during scanning mode.

[0026] In this way, the radar sensor operates in scan mode with pulses but at varying duty cycles. This duty cycle variation reduces power consumption without decreasing the detection range because it maintains periods of high duty cycle (for long-range detection). The maximum duty cycle used by the system corresponds to the maximum detection range required by the application. Furthermore, duty cycles smaller than this maximum are used as part of cyclic operation in scan mode. For example, each frame has enough pulses to identify possible motion within the corresponding detection range.

[0027] In response to the detection of potential motion in scan mode, the controller updates the cyclic operation of the radar transmitter to provide a motion confirmation mode. In this way, scan mode can be simply used to detect potential motion, which can then be verified using a motion confirmation mode selected for detection within an appropriate range. Therefore, when the radar sensor detects potential motion from a data sample of a frame in a scan mode with a specific duty cycle, a new variable duty cycle scheme is used to quickly confirm whether the potential motion is valid.

[0028] For example, each cycle of the scan mode includes a column of frames whose duty cycle increases in a stepwise manner over time. This provides a simple control method where the duty cycle increases stepwise over the duration of the periodic cycle. This means that the scan starts from the smallest detection range. This means that the lowest power consumption is used initially. If this is sufficient for motion detection, it means that motion can be detected in the most energy-efficient way. Only when no motion is detected is a larger sensing range (with a larger duty cycle, and therefore higher power consumption) needed.

[0029] For example, each cycle of the scanning mode includes frames with the following duty cycle range: from a minimum duty cycle (e.g., 0.5%) within the range of 0.1% to 1%, to a maximum duty cycle (e.g., 5%) within the range of 3% to 10%. For example, each cycle may have five frames. For example, the radar pulse set for each frame includes 16 to 128 pulses (e.g., 64 pulses). For example, the duration of each frame (in scan mode and motion compensation mode) is between 50 ms and 100 ms.

[0030] During motion confirmation mode, preferably, one or more cycles are provided, each cycle including at least a frame having a duty cycle corresponding to the frame in the scan mode where motion was detected.

[0031] The motion confirmation mode can also be a stepped scheme, but this cycle (or multiple cycles) only includes the duty cycle at which motion was detected during the scan mode and a larger duty cycle. The motion confirmation mode can be used for one or more cycles until a valid motion is confirmed or not confirmed. The sensor then returns to the scan mode.

[0032] The controller is configured, for example, as follows:

[0033] Motion confirmation mode begins immediately after motion is detected in the scanning mode; and

[0034] Set the first frame of the motion confirmation mode to have the same duty cycle as the frame in the scan mode that detects motion.

[0035] Therefore, once motion is detected, the duty cycle is repeated as the start of the motion confirmation mode.

[0036] The present invention also provides a method for operating a radar sensor, the method comprising:

[0037] The radar transmitter that controls the radar sensor operates cyclically during scanning mode, where each cycle includes a sequence of frames;

[0038] During each frame of the scanning mode, the radar transmitter is controlled to emit a set of radar pulses with an associated duty cycle for the frame, and the radar pulses reflected from the monitoring area of ​​the radar sensor are received at the radar receiver.

[0039] Interpreting signals from the radar receiver to detect possible motion during scanning mode; and

[0040] In response to motion detection in scanning mode, the cyclic operation of the radar transmitter is updated to provide motion confirmation mode.

[0041] This provides a method for operating the radar sensor as described above.

[0042] For example, each cycle of the scan mode includes frames with the following duty cycle range: from a minimum duty cycle in the range of 0.1% to 1% to a maximum duty cycle in the range of 3% to 20%.

[0043] The present invention also provides a computer program including computer program code, which, when run on a computer, is adapted to implement the above-described method.

[0044] These and other aspects of the invention will become clear and illustrated with reference to the embodiments described below. Attached Figure Description

[0045] To better understand the invention and to more clearly show how it can be implemented, reference will now be made to the accompanying drawings by way of example only, in which:

[0046] Figure 1 The pulse operation of the radar sensor is shown;

[0047] Figure 2 A radar sensor that can be controlled according to the present invention is shown;

[0048] Figure 3 A variable duty cycle scheme is shown;

[0049] Figure 4 Showing more details Figure 3 Scanning mode;

[0050] Figure 5 An example of radar switching between two different duty cycle schemes is shown; and

[0051] Figure 6 The method employed by radar sensors is shown. Detailed Implementation

[0052] The invention will be described with reference to the accompanying drawings.

[0053] It should be understood that while the detailed description and specific examples illustrate exemplary embodiments of the apparatus, system, and method, they are intended for illustrative purposes only and are not intended to limit the scope of the invention. These and other features, aspects, and advantages of the apparatus, system, and method of the present invention will be better understood from the following description, the appended claims, and the accompanying drawings. It should be understood that the drawings are merely schematic and not drawn to scale. It should also be understood that the same reference numerals are used throughout the drawings to indicate the same or similar parts.

[0054] This invention provides a radar sensor having a radar transmitter controlled to operate in cycles, wherein each cycle comprises a sequence of frames, and each frame has an associated (fixed) duty cycle. Signals from a receiver of the radar sensor are interpreted to detect possible motion. A motion confirmation mode is then used to provide more accurate motion signals. The duty cycle variation reduces power consumption without reducing the detection range because it maintains periods of high duty cycle (for wide-range detection).

[0055] Figure 2 A radar sensor that can be controlled according to the present invention is shown.

[0056] The radar sensor includes a radar transmitter 20 for transmitting radar pulses and a radar receiver 22 for receiving radar pulses reflected from the monitoring area of ​​the radar sensor. A controller 24 is used to control the timing of the operation of the radar transmitter. The interpretation of the radar receiver signal is synchronized with the operation of the radar transmitter.

[0057] In one example, controller 24 can also function as a lighting system controller for controlling lighting device 26. Therefore, the lighting is controlled based on motion detection (in a known manner) to identify the presence of a moving object. The moving object to be detected can be a person or animal, or, in the case of a street lighting application, a vehicle. However, the invention can be applied to any device that uses motion detection for control.

[0058] This invention relates to the control of the duty cycle of radar sensors (as per reference). Figure 1 (As explained), and will not change the basic conceptual approach to motion detection. Therefore, the concept of motion detection will not be described in detail.

[0059] In short, radar sensors determine the Doppler frequency shift based on phase difference measurements (between the transmitted and received signals) to detect moving objects, and optionally also detect the object's velocity and direction. Radar sensors operate in the microwave frequency band.

[0060] This invention is based on operating a radar sensor with pulse operation but with a varying duty cycle, in order to further reduce power consumption without reducing its detection range.

[0061] First, based on the application requirements, identify the maximum duty cycle (D) corresponding to the maximum detection range. max Then, further determine that it is less than D. max Several duty cycles. For example, if D max If the duty cycle is 5%, other possible examples of duty cycles could be 3%, 2%, 1%, or 0.5%.

[0062] During pulse operation, the radar sensor employs a variable duty cycle scheme to form a scanning pattern, rather than using a fixed duty cycle, such as... Figure 3The stepped scheme shown depicts the duty cycle as it changes over time.

[0063] In one cycle of 30, the radar sensor will reduce the duty cycle from the minimum value (D) min ) gradually increases to the maximum value (D) max A step of the staircase is called frame 32.

[0064] Each frame 32 contains multiple pulses (e.g., 64) with the same duty cycle.

[0065] The pulses in each individual frame should be sufficient to generate enough data samples for the radar sensor to determine whether possible motion exists within the corresponding detection range. The typical duration of a frame is approximately 50ms-100ms. A loop contains multiple frames.

[0066] Figure 3 The example has five frames 32 per loop 30, with duty cycles as listed above. More generally, duty cycles can range from a minimum duty cycle in the range of 0.1% to 1% to a maximum duty cycle in the range of 3% to 10%.

[0067] Figure 3 The scan pattern shown can be considered a scan pattern and used when no motion is detected.

[0068] Figure 4 The scanning mode is shown in more detail.

[0069] The entire loop 30 has five frames.

[0070] The duty cycle of the first frame 40a is 0.5%, the duty cycle of the second frame 40b is 1.0%, the duty cycle of the third frame 40c is 2%, the duty cycle of the fourth frame 40d is 3%, and the duty cycle of the fifth frame 40e is 5%. In this example, all frames have 64 pulses.

[0071] For example, at a sampling rate of 1 kHz, the duration of a frame containing 64 pulses (i.e., data samples) is 64 ms. Therefore, the total duration of a loop is 320 ms.

[0072] Within each cycle, the duty cycle and the detection range of the radar sensor gradually increase. By using this variable duty cycle scheme, the actual power consumption is reduced from 5% to 2.3% compared to a constant 5% duty cycle.

[0073] When the radar sensor scans a frame of a scanning mode (with a specific duty cycle, such as D), M When potential motion is detected in the data sample, it will follow a new variable duty cycle scheme. This is called the motion confirmation mode.

[0074] This motion confirmation mode is used to confirm whether a possible motion is valid. The motion confirmation mode also uses a stepped, frame-by-frame adjustment of the duty cycle, but each frame only contains the duty cycle D at the location where motion was detected during the scan mode. M or greater than D M Duty cycle.

[0075] The radar sensor operates in a new motion confirmation mode for one or more cycles until a valid motion is confirmed or not confirmed, and then switches back to the scan mode, where each cycle contains all duty cycles.

[0076] With an additional motion confirmation mode, the frames during the scanning mode can be short enough that they only need to detect possible motion events. Detection using short frames will enable motion detection, but the confidence level will be lower. Therefore, detection can be correlated with other factors such as noise (i.e., false positives can occur).

[0077] In particular, in scan mode, lenient criteria can be supported to ensure that all suspicious motions are identified, ensuring that no detection is missed. The short frames in scan mode also provide a more agile response to long-distance motion.

[0078] In confirmation mode, stricter criteria can be used to filter out unwanted movements. For example, a radar sensor placed outdoors might detect the swaying of trees or leaves in scanning mode, but this could be removed in confirmation mode using appropriate sensing algorithms. Therefore, confirmation mode can help reduce false positives so that only true positive results are ultimately reported.

[0079] In this way, the entire cycle time during the scan mode can be kept as short as possible to query the entire depth range at a sufficiently fast repetition rate without missing any movement at any location within the entire maximum range. Therefore, the minimum expected response time is still guaranteed.

[0080] For example, the duration of the confirmation mode depends on the complexity of the detection algorithm and the acceptable response time for confirming a valid detection. Typically, for example, the confirmation mode lasts from a few hundred milliseconds to a few seconds (usually <5 seconds).

[0081] In this way, the power consumption of the radar is minimized, while the maximum detection range and minimum response time are guaranteed.

[0082] Figure 5 This illustrates an example of a radar switching between two modes during its operation: scanning mode and motion confirmation mode.

[0083] The radar sensor operates by default in pulse scan mode to detect any possible motion.

[0084] Once a specific duty cycle is achieved (e.g., D) M If potential motion is detected within a specific frame, the sensor immediately switches to motion confirmation mode to quickly determine whether the potential motion is valid. The radar sensor remains in motion confirmation mode for one or more cycles until valid motion is confirmed or not, at which point it switches back to scanning mode. If valid motion is confirmed, the radar sensor generates a motion call.

[0085] like Figure 5 As shown, in the first example, potential motion was detected in the third frame 50a (duty cycle 2%) of the second loop. The radar sensor then switched to motion confirmation mode. In this mode, the loop contains only three duty cycles: 2%, 3%, and 5%.

[0086] As shown in the figure, the motion confirmation mode begins immediately after frame 50a of the motion-detecting scan pattern. It begins by repeating the same duty cycle (2% in this example) as frame 50a of the motion-detecting scan pattern.

[0087] In this example, the sensor completes the confirmation using only one cycle of the motion confirmation mode (since there are now three frames during which motion will be detected).

[0088] Perform motion-based signal processing to confirm motion.

[0089] In the second example, potential motion was detected in the fourth frame 50b of the first loop (duty cycle of 3%). The radar sensor switched to motion confirmation mode, which contains only two duty cycles per loop: 3% and 5%. In this example, confirmation of valid motion requires two motion confirmation mode loops (because after the first loop, there are only three frames during which motion can be confirmed).

[0090] Figure 6 The method employed by radar sensors is shown.

[0091] In step 60, the sensor operates in scanning mode. As described above, this involves operating in a frame sequence loop, and during each frame, transmitting a set of radar pulses with an associated duty cycle for that frame, wherein the loop includes frames with a duty cycle that increases stepwise over time.

[0092] In step 62, the radar sensor signal analysis determines whether possible motion has been detected. This analysis occurs during each frame.

[0093] For typical low-power signal processing methods, the signal is collected for each pulse and buffered until the end of the frame. Then, a round of signal processing can be performed on the entire data frame. Therefore, motion detection usually occurs at the end of each frame.

[0094] If no motion is detected, the scanning mode continues.

[0095] If potential motion is detected, the motion confirmation mode is entered in step 64.

[0096] If movement is confirmed in step 66, a movement call is issued in step 68, typically used to control the device based on the detected movement. For example, a lighting system may be configured to turn on due to motion detection to indicate the presence of a moving person or vehicle.

[0097] If the motion may not be confirmed in step 66, the scan mode is restored.

[0098] By studying the accompanying drawings, the disclosure, and the appended claims, those skilled in the art can understand and implement variations of the disclosed embodiments in practicing the claimed invention. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality.

[0099] The functions implemented by a processor can be implemented by a single processor or multiple individual processing units, which can be considered together as a "processor". In some cases, such processing units can be located far apart from each other and communicate with each other via wired or wireless means.

[0100] The fact that certain measures are referenced in mutually different dependent claims does not mean that a combination of these measures cannot be advantageous.

[0101] Computer programs can be stored / distributed on suitable media, such as optical storage media or solid-state media provided or as part of other hardware, but can also be distributed in other forms, such as via the Internet or other wired or wireless telecommunications systems.

[0102] If the term "adapted as" is used in the claims or description, it should be noted that "adapted as" is intended to be equivalent to "configured as". If the term "arranged" is used in the claims or description, it should be noted that the term "arranged" is intended to be equivalent to the term "system", and vice versa.

[0103] No reference numerals in the claims should be construed as limiting the scope.

Claims

1. A radar sensor, comprising: Radar transmitter (20), used to transmit radar pulses; A radar receiver (22) is used to receive the radar pulse after it has been reflected from the monitoring area of ​​the radar sensor; as well as Controller (24) is used to control the timing of the operation of the radar transmitter. The controller is configured during the scan mode to: - Control the radar transmitter to operate in a cycle, wherein each cycle (30) includes a sequence of frames (32) whose duty cycle increases in a stepwise manner from one frame to another over time; - During each frame (32), the radar transmitter is controlled to transmit a set of radar pulses with an associated duty cycle for the frame; as well as - Interpret the signals from the radar receiver to detect possible motion. The controller is configured to update the cyclic operation of the radar transmitter to provide a motion confirmation mode in response to the detection of possible motion during the scanning mode. This motion confirmation mode uses a step-by-frame adjustment of the duty cycle, and each frame contains only the duty cycle D at which motion was detected during the scanning mode. M or greater than D M Duty cycle.

2. The radar sensor of claim 1, wherein each cycle of the scanning mode comprises frames having a duty cycle ranging from a minimum duty cycle to a maximum duty cycle, the minimum duty cycle being in the range of 0.1% to 1%, and the maximum duty cycle being in the range of 3% to 10%.

3. The radar sensor according to any one of claims 1 to 2, wherein the duration of each frame is between 50 ms and 100 ms.

4. The radar sensor according to any one of claims 1 to 3, wherein during the motion confirmation mode, one or more cycles are provided, each of the one or more cycles including at least a frame having a duty cycle corresponding to the frame in the scanning mode that detects possible motion.

5. The radar sensor of claim 4, wherein the controller is configured to: The motion confirmation mode begins immediately after the frame in the scanning mode where the motion is detected; and The first frame of the motion confirmation mode is set to have the same duty cycle as the frame in the scanning mode that detects motion.

6. The radar sensor according to any one of claims 1 to 5, wherein the controller is configured to execute the motion confirmation mode until the detected motion is confirmed or not confirmed.

7. A lighting system, comprising: lighting fixtures; Lighting controller; as well as The radar sensor according to any one of claims 1 to 6 is used to provide a confirmed motion detection signal to the lighting controller.

8. A method for operating a radar sensor, comprising: (60) The radar transmitter controlling the radar sensor operates cyclically during scanning mode, wherein each cycle includes a sequence of frames, the duty cycle of which increases in a stepwise manner from one frame to another over time. During each frame of the scanning mode, the radar transmitter is controlled to emit a set of radar pulses with an associated duty cycle for the frame, and the radar pulses after reflection from the monitoring area of ​​the radar sensor are received at the radar receiver. (62) Interpret the signals from the radar receiver to detect possible motion during the scanning mode; as well as In response to motion detection, the cyclic operation of the radar transmitter is updated to provide a motion confirmation mode (64), which uses a stepwise frame-by-frame adjustment of the duty cycle, and each frame contains only the duty cycle D in which motion was detected during the scanning mode. M or greater than D M Duty cycle.

9. The method of claim 8, wherein each cycle of the scanning mode comprises a frame having a duty cycle ranging from a minimum duty cycle to a maximum duty cycle, the minimum duty cycle being in the range of 0.1% to 1%, and the maximum duty cycle being in the range of 3% to 10%.

10. The method of claim 9, comprising: During the motion confirmation mode, one or more cycles are provided, the frames of the one or more cycles having at least a duty cycle corresponding to the frame in the scanning mode in which motion was detected.

11. The method of claim 10, comprising: The motion confirmation mode begins immediately after the frame in which the motion is detected during the scanning mode, and the first frame of the motion confirmation mode has the same duty cycle as the frame in the scanning mode in which the motion is detected.

12. The method according to any one of claims 8 to 11, comprising: Perform the motion confirmation mode operation until the detected motion is confirmed or not confirmed.

13. A computer program comprising computer program code, wherein when the program is run on a computer, the computer program code is adapted to implement the method according to any one of claims 8 to 12.

Images