An ultrasound sensor apparatus and an operating method thereof

Abstract

Aspects of the present invention relate to an ultrasound sensor apparatus for ultrasound sensing in air, and a method of ultrasound sensing in air. The method of ultrasound sensing in air comprises, during each of a plurality time periods, encoding at least one set of ultrasound frequencies from a plurality of ultrasound frequencies into at least one transmission signal, and transmitting the at least one transmission signal by one or more transmitters of an ultrasound sensor apparatus located in a local environment. The method further comprises receiving, by a plurality of receivers of the ultrasound sensor apparatus, at least one received signal, and determining that the at least one received signal is a reflection of the corresponding at least one transmission signal from the local environment by decoding the at least one received signal. Local environment data can then be generated based on the decoded at least one received signal, and an image of at least a portion of the local environment may then be generated based on the local environment data.

Description

AN ULTRASOUND SENSOR APPARATUS AND AN OPERATING METHOD THEREOFTECHNICAL FIELD

[0001] Embodiments described herein relate generally to the use of ultrasound sensors for environment imaging.BACKGROUND

[0002] Current sensors used in autonomous systems, such as smart robots, drones, and self-driving cars may employ multiple sensor modalities, such as radar, lidar, cameras, or microphones. However, almost all current sensor systems share common problems in real world environments, affecting their range, detection capabilities, and reliability. For example, optical and radar sensor systems in vehicle navigation do not always function optimally in challenging environments, such as in rain, fog, or excessive dust. This can then render autonomous vehicles or other such systems blind in those real-world conditions.SUMMARY OF INVENTION

[0003] The present application relates to the field of ultrasound sensor systems and apparatuses.

[0004] In accordance with a first aspect of the invention, there is provided a method of ultrasound sensing in air, the method comprising: during each of a plurality time periods: encoding at least one set of ultrasound frequencies from a plurality of ultrasound frequencies into at least one transmission signal, transmitting the at least one transmission signal by one or more transmitters of an ultrasound transceiver located in a local environment, receiving by a plurality of receivers of the ultrasound transceiver at least one received signal, determining that the at least one received signal is a reflection of the corresponding at least one transmission signal from the local environment by decoding the at least one received signal, and generating local environment data based on the decoded at least one received signal.

[0005] This first aspect of the invention may also include generating an image of at least a portion of the local environment based on the local environment data.

[0006] Any of the following may be applied to the above first aspect of the invention.

[0007] Optionally, the encoding of the at least one set of ultrasound frequencies into the at least one transmission signal may comprise encoding the at least one set of ultrasound frequencies using one or more of amplitude modulation, frequency modulation, or phase-shift modulation.

[0008] Optionally, for at least one of the plurality of time periods, the encoding of the at least one set of ultrasound frequencies may be based upon the local environment data generated based on at least one signal received during a preceding time period.

[0009] Optionally, for each of the plurality of time periods, the encoding of the at least one set of ultrasound frequencies may be different to the encoding of the at least one set of ultrasound frequencies of a preceding time period, and / or for each of the plurality of time periods, the encoding of the at least one set of ultrasound frequencies may be different to the encoding of any other of the at least one set of ultrasound frequencies of that time period.

[0010] Optionally, the image of at least a portion of the local environment may be a three-dimensional image.

[0011] Optionally, the plurality of receivers may receive the at least one received signal when operating as a phased array.

[0012] Optionally, the method may further comprise at least one of: determining the location of an object in the local environment based on the local environment data; and generating an image of the object based on the local environment data.

[0013] Optionally, the method may further comprise: defining a first region and a second region in the local environment, the first region being defined being less than a first distance from the plurality of receivers of the ultrasound transceiver located in the local environment, and the second region being more than the first distance and less than a second distance from the plurality of receivers of the ultrasound transceiver located in the local environment; and the encoding of the at least one set of ultrasound frequencies may comprise encoding a set of ultrasound frequencies from the plurality of ultrasound frequencies into a transmission signal for each region, where the encoding of the set of ultrasound frequencies for the first region may be based on the first distance and the encoding of the set of ultrasound frequencies for the second region is based on second distance; and the transmitting of the at least one transmission signal may comprise transmitting the transmission signal for each of the first and second regions; and the determining may comprise determining that at least one received signal is a reflection of a transmission signal for the first region or the second region of the local environment by decoding the at least one received signal.

[0014] Optionally, the plurality of receivers may include the one or more transmitters, and the at least one receiver of the plurality of receivers that includes the one or more transmitters may be configured to operate as a transceiver.

[0015] In accordance with a second aspect of the invention, there is provided an ultrasound sensor apparatus for ultrasound imaging in air, the ultrasound sensor apparatus comprising: at least one transmitter; a plurality of receivers; and a driver module configured to drive the at least one transmitter and the plurality of receivers; wherein the plurality of receivers are arranged in a non-periodic arrangement.

[0016] Any of the following may be applied to the above second aspect of the invention.

[0017] Optionally, the ultrasound sensor apparatus may further comprise: a communications module configured to transmit signal data associated with signals received by the plurality of receivers.

[0018] Optionally, the ultrasound sensor apparatus may further comprise a control module, where the control module may be configured to: encode one or more sets of ultrasound frequencies into one or more transmission signals for transmission by the at least one transmitter; and decode received signals, received by the plurality of receivers; and generate local environment data based on the decoded signals. The ultrasound sensor apparatus may further comprise a processing module, where the processing module may be configured to generate, using the local environment data, an image of at least a portion of the local environment around the ultrasound sensor apparatus.

[0019] Optionally, the non-periodic arrangement of the plurality of receivers may be a Fibonacci arrangement.

[0020] Optionally, the plurality of receivers may be configured to be operated as a phased array.

[0021] Optionally, the at least one transmitter and the plurality of receivers may be arranged in a stack.

[0022] Optionally, the plurality of receivers may include the at least one transmitter; and the at least one receiver of the plurality of receivers that includes the at least one transmitter may be configured to operate as a transceiver.

[0023] Optionally, the ultrasound sensor apparatus may be configured to carry out any of the methods of the first aspect of the invention above.

[0024] Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and / or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and / or features of any embodiment can be combined in any wayand / or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and / or incorporate any feature of any other claim although not originally claimed in that manner.FIGURES

[0025] In the following, embodiments will be described with reference to the drawings in which:

[0026] Fig. 1 shows an illustrated example of the layers of an ultrasound sensor apparatus according to some embodiments.

[0027] Fig. 2 shows an example cross-section of the ultrasound sensor apparatus for a single transmitter, receiver, or transceiver element, including the layers of the housing of the apparatus and the acoustic channel directing ultrasound signals to or from the transmitter, receiver, or transceiver element.

[0028] Fig. 3 shows various example arrangements of elements of a ultrasound sensor apparatus according to some embodiments.

[0029] Fig. 4 shows a flowchart of a method of operating an ultrasound sensor apparatus according to some embodiments.

[0030] Fig. 5 shows an example definition of regions in a local environment and probing of those regions by an ultrasound sensor apparatus, according to some embodiments.

[0031] Fig. 6 shows an example plot of transmission signals and received signals, according to some embodiments.

[0032] Fig. 7 shows an example image generated based on local environment data generated based on received signals, according to some embodiments.DETAILED DESCRIPTION

[0033] The present application is directed towards the use of ultrasound sensors. In particular, an ultrasound sensor apparatus 100, and a method of ultrasound sensing in air, in accordance with various embodiments of the present invention is described herein with reference to the accompanying Figures 1 to 7.

[0034] Such ultrasound sensors comprise one or more receivers and one or more emitters (or transmitters) to provide spatial data associated with the environment within the range of those sensors, which can then be used to generate imagery of at least a part of that environment. Such imaging may be achieved in real time, allowing for such ultrasound sensors to be applied in a variety of different contexts and fields. As non-limiting examples, such fields may be smart robots, drones, vehicles (e.g. autonomous, semi-autonomous, manually-driven) or in a medical capacity (e.g. care home patient sensing).

[0035] By employing ultrasound in this manner, the ultrasound sensors of the present application are able to function reliably and with high accuracy in challenging environments, such as in rain, fog, or in the presence of high levels of airborne dust. Such ultrasound sensors may be implemented in isolation to provide specific ultrasound imaging, or may be implemented in conjunction with other imaging techniques, such as radar, lidar, visual cameras, or microphones.

[0036] Figure 1 shows an example of the ultrasound sensor apparatus 100 according to some embodiments. Here, the ultrasound sensor apparatus 100 comprises at least one transmitter, Tx, 110, and at least one receiver, Rx, 120. It will be appreciated that, while the arrangement of Figure 1 shows either Tx elements 110 or Rx elements 120, this approach may also be applied to transceiver elements where such elements may function as both transmitters and receivers (i.e. a TX / Rx array of elements), as discussed further below.

[0037] In some embodiments, the at least one transmitter, Tx, 110 may comprise a plurality of transmitters, Tx, and be referred to as a transmitter, Tx, array. In some embodiments, the Tx array may comprise a range of different ultrasound transducers having different operating voltages and frequencies. This allows the Tx array to be designed in a manner that is more accurate and tailor-made for the intended operating environment for the ultrasound sensor apparatus 100.

[0038] In some embodiments, the at least one receiver, Rx, 120 may comprise a plurality of receivers, Rx, and be referred to as a receiver, Rx, array.

[0039] In some embodiments, the at least one Tx and at least one Rx may be located together, or co-located, on a single module of the ultrasound sensor apparatus 100. For example, the ultrasound sensor apparatus 100 may comprise one or more modules 105, and the at least one Tx and the at least one Rx may be co-located within the same module 105.

[0040] In some embodiments, the same array of elements may function as both the transmitter, Tx, array and the receiver, Rx, array (i.e. the Tx array and Rx array may function as a transceiver). Here, the array of elements may be configured such that they function as the transmitter, Tx, array for a set period of time (e.g. a transmission period), before switching to function as the receiver, Rx, array for a set period of time (e.g. a receiving period). This arrangement is shown in the illustrative example of Figure 1, where one or more of the elements of the Tx / Rx array may function as both a transmitter 110 and a receiver 120.

[0041] In some embodiments, at least one module of the one or more modules 105 of the ultrasound sensor apparatus 100 comprises a series of layers, forming a stack. An expanded illustration of such a stack is shown in Figure 1. In such embodiments, the one or more modules 105 of the stack may communicate with each other when the ultrasound sensor apparatus 100 is in operation.

[0042] By being configured in a stack configuration, the ultrasound sensor apparatus 100 is more compact when installed in certain scenarios and environments, for example when installed on a vehicle.

[0043] It will be understood that the various modules and functionalities discussed herein may be implemented in the ultrasound sensor apparatus 100, where that ultrasound sensor apparatus 100 is configured in a stack configuration. Alternatively, in some embodiments, some modules of the one or modules 105 may be arranged in a stack configuration, and some modules of the one or more modules 105 may be arranged separately to the stack configuration (for example, if it is desired that some modules be located separately to the stack).

[0044] In some embodiments, some modules of the one or more modules 105 of the ultrasound sensor apparatus 100 described herein may be co-located on the same layer within the stack.

[0045] It will also be understood that, in some embodiments, the various modules and functionalities discussed herein may be implemented in the ultrasound sensor apparatus 100, where that ultrasound sensor apparatus 100 is not configured in a stack configuration. For example, in some scenarios, some modules of the one or more modules 105 may be arranged adjacent to each other.

[0046] Where the at least one module of the one or more modules 105 comprises a stack of layers, the at least one Tx and the at least one Rx may be co-located on the same layer within a stack of one module of the one or more modules 105. In other embodiments where one module of the one or more modules 105 comprises a series of layers in a stack, the at least one Tx and the at least one Rx may be located on different layers of that stack.

[0047] In some embodiments, the at least one Tx and at least one Rx may be located in separate modules of the ultrasound sensor apparatus 100.

[0048] In some embodiments, the ultrasound sensor apparatus 100 may include a driver module 130 for driving the at least one Tx and at least one Rx. Where the one or more modules 105 of the ultrasound sensor apparatus 100 comprises a series of layers, forming a stack, the driver module 130 maybe located in one of those layers.

[0049] The driver module 130 may be configured to provide a signal to each of the at least one Tx of the ultrasound sensor apparatus 100.

[0050] When the driver module 130 is configured to drive the at least one transmitters, Tx, a single signal may be provided to each of the at least one transmitters, Tx, such that a single ultrasound signal is emitted from each of the at least one transmitters, Tx.

[0051] Alternatively, where there are a plurality of transmitters, Tx, the driver module 130 may be configured to drive the plurality of Tx by providing a different signal to each of the plurality of transmitters, Tx, such that a unique ultrasound signal is emitted from each of the plurality of transmitters, Tx. As a further alternative, the plurality of transmitters, Tx, may be formed of subgroups of transmitters, Tx, where the driver module 130 provides a unique signal to each subgroup, such that each subgroup of transmitters, Tx, emits a unique ultrasound signal.

[0052] As such, in some embodiments the driver module 130 may be configured to provide a signal to each of the plurality of transmitters, Tx, that has a different phase angle to the signal provided to each of the other transmitters, Tx, resulting in the steering of the ultrasound signals emitted by the transmitter, Tx, array. Here, the difference in the phase angle between each different signal provided to each of the plurality of transmitters, Tx, may be consistent, resulting in a predictable steering of the ultrasound signals emitted from the plurality of transmitters, Tx. In such embodiments, the transmitter, Tx, array (or, in some embodiments, the receiver, Rx array) may be said to be operating as a "phased array".

[0053] In some embodiments, the ultrasound sensor apparatus 100 may include a communication module 135 for receiving and transmitting data to external systems. Here, the communications module 135 may be configured to transmit data relating to the local environment (e.g. a spatial representation of or spatial data relating to the local environment) generated based on received ultrasound signals to external systems or other electronics devices.

[0054] In some embodiments, the communications module 135 may also be configured to transmit images or spatial representations of the local environment generated based on decoded received ultrasound signals to external systems or electronics devices for further processing.

[0055] In some embodiments, the communications module 135 may also be configured to transmit received ultrasound signals to external systems or electronics devices prior to any processing (e.g. prior to decoding, or prior to generating local environment data, or prior to the determination of any objects in the local environment).

[0056] Such external systems or electronics devices may be, for example, a cloud service, one or more computers, an embedded vehicular computer, a tablet, and / or a smartphone. The transmission of any data discussed above by the communicationsmodule 135 to such external systems or electronics devices may utilise any known method, either wired or wireless.

[0057] In some embodiments, the ultrasound sensor apparatus 100 may include a control module 140. The control module 140 may be configured to select and encode a set of ultrasound frequencies into one or more transmission signals for transmission by the at least one transmitter, Tx. The encoded transmission signals may be output to the driver module 130, where the driver module 130 then processes the encoded transmission signals and provides corresponding signals to the at least one transmitter, Tx (or, in some embodiments, the transmitter array) to be emitted. It will be appreciated that the encoded transmission signals may alternatively be output to modules other than the driver module 130 (e.g. modules that are external to the ultrasound sensor apparatus 100), which may then be provided to the at least one transmitter, Tx (or, in some embodiments, the transmitter array) for transmission.

[0058] In some embodiments, the ultrasound sensor apparatus 100 may include a processing module 145. The processing module 145 may be configured to receive signals received by the at least one receiver (or, in some embodiments, the receiver array, Rx). Here, the processing module 145 may decode the received signals, and generate local environment data based on the decoded signals, where the local environment data includes spatial data for the local environment (e.g. the locations in the local environment where a transmitted signal has been scattered or reflected, before being received by the at least one receiver or Rx array). For example, the processing module 145 may decode a signal received by the at least one receiver, Rx (or, in some embodiments, the receiver array), generate spatial data (e.g. in the form of local environment data) associated with the local environment based on the decoded signal and, in some embodiments, additionally determine the location of objects in the local environment around the ultrasound sensor apparatus 100 (e.g. the direction and distance of such an object in the local environment) using the spatial data.

[0059] The processing module 145 may also employ data associated with other factors when generating local environment data from the decoded received signals. For example, the processing module 145 may make use of one or more of: the known geometry of Tx and / or Rx arrays, the speed of the transmitted signals inferred from the air temperature of the local environment (this may be an assumed value, or may be provided by one or more temperature sensors external to the sensor apparatus 100), or the specific configuration of the associated transmitted signals.

[0060] The generated local environment data then includes data that describes at least some spatial aspects of the local environment around the ultrasound sensor apparatus 100. In some embodiments, generated local environment data may take theform of heat map of at least a part of the local environment, a point cloud of at least a part of the local environment, or any other spatial representation or spatial data relating to at least a part of the local environment.

[0061] Where the processing module 145 determines the location of objects in the local environment around the ultrasound sensor apparatus 100, the processing module 145 may additionally determine the size and shape of such objects in the local environment, either in two-dimensions or in three-dimensions, based on the local environment data generated based on the decoded signals received by the at least one receiver, Rx (or, in some embodiments, the receiver array). The processing module 145 may then generate a two or three-dimensional image of the local environment, or of an object located within the local environment, based on the generated local environment data.

[0062] It will be appreciated that the various functions of the processing module 145 discussed here may be carried out by a single module of the ultrasound sensor apparatus 100, or may be carried out by separate sub-modules of the ultrasound sensor apparatus 100. For example, received signals may be decoded, and local environment data generated, by a single module or the ultrasound sensor apparatus 100, and the location of objects in the local environment around the ultrasound sensor apparatus 100 may then be determined by a separate sub-module of the ultrasound sensor apparatus 100 (located either on the stack of one or more modules 105, or externally to the stack of one or more modules 105). It will also be appreciated that, in some embodiments, the processing module 145 and / or the driver module 130 may therefore form part of the control module 140, or vice versa.

[0063] The inclusion of the control module 140 allows for the ultrasound sensor apparatus 100 to process signals for transmission (e.g. select and encode the signals for transmission), and the inclusion of the processing module 145 allows for the ultrasound sensor apparatus 100 to then process received signals (e.g. using known array geometry, an inferred speed of sound based on assumed or measured local air temperature, and known factors of the transmitted signal) in order to verify that a received signal corresponds to an earlier transmitted signal, and to generate local environment data from that received signal. As a result, the local environment around the ultrasound sensor apparatus 100 can then be imaged accurately in two or three dimensions and in real time by the apparatus with no requirement for any processing to be carried out by other separate systems. For example, where the ultrasound sensor apparatus 100 is employed in a vehicle (e.g. a manual, autonomous, or semi- autonomous vehicle), no other onboard systems of the vehicle are required to carry out the imaging of the at least a portion of the local environment or, in some embodiments, object detection within the local environment.

[0064] It will be appreciated that where the ultrasound sensor apparatus 100 may operate entirely independently of separate external systems, it may similarly be operated in conjunction with externals systems, for example to improve accuracy. For example, the ultrasound sensor apparatus 100 may output received signals as data to an external system, either before or after decoding, so that such an external system may then analyse the received signals to carry out the imaging of the local environment. In such scenarios, the output data may be combined with data from other ultrasound sensor apparatuses, or from sensor systems operating in other sensor modalities, in order to accurately image the local environment.

[0065] Figure 2 shows an example cross-section of the structure of the ultrasound sensor apparatus 100 around one element of the Tx / Rx array, according to some embodiments. Here, the element may take the form of a surface mounted MEMS microphone, although it will be appreciated that other acoustic microphone systems may be employed.

[0066] It will also be appreciated that the element shown in Figure 2 may be either a transmitter 110, a receiver 120, or a transceiver element configured to function as both a transmitter 110 and a receiver 120. As such, where the following discussion with reference to the arrangement of Figure 2 considers a receiver element 120 of the Rx array, it will be appreciated that the same principles nonetheless apply to a transmitter element 110 of the Tx array, or a transceiver element of a RX / Tx array.

[0067] The structure of the housing of the ultrasound sensor apparatus 100 around one or more of the receiver elements 120 of the Rx array may comprise a series of layers, where those layers may include a first PCB 120a, a second PCB 120b, an acoustically transparent material 121 layer, an acoustic absorber 122 layer, and an outer casing 123 of the ultrasound sensor apparatus 100. A channel 125 is then formed in the first PCB 120a, second PCB 120b, the acoustic absorber 122 layer, and the outer casing 123.

[0068] It will be appreciated that the arrangement of Figure 2 is merely an illustrative example, and other intervening layers may be included, in addition to those shown in that Figure.

[0069] In the embodiment of Figure 2, the receiver element 120 may be mounted on the first PCB 120a, which is a dedicated PCB for that receiver element. The first PCB 120a may then be coupled to the surface of a larger second PCB 120b of the ultrasound sensor apparatus 100. The second PCB 120b may be a PCB for controlling or driving the wider Rx array.

[0070] In some embodiments, the acoustically transparent material 121 may be formed over or coupled to at least a portion of the opposing surface of the second PCB 120b,or over at least a portion of the surface of an intervening layer formed over or coupled to at least a portion of the opposing surface of the second PCB 120b.

[0071] The acoustically transparent material 121 may allow acoustic or ultrasound waves to be transmitted across the layer with little or no absorption, whilst minimising or preventing dust, particulates, or moisture from passing across the acoustically transparent material 121. In some embodiments, the acoustically transparent material 121 may be formed of a rigid, semi-rigid, or flexible fabric material that is suitably acoustically transmitting.

[0072] The acoustic absorber 122 may then be formed over or coupled to the opposing surface of the acoustically transparent material 121. Here, the acoustic absorber 122 may be designed to minimise or prevent acoustic or ultrasound waves travelling laterally through the acoustic absorber 122 (e.g. in a direction parallel to the plane of the acoustic absorber 122 and / or the outer casing 123). In some embodiments, the acoustic absorber 122 may be formed of a rubber or a similar acoustically-absorbing material.

[0073] In some embodiments, the acoustically transparent material 121 may alternatively be formed over or coupled to at least a portion of the opposing surface of the acoustic absorber 122, or over at least a portion of the surface of an intervening layer formed over or coupled to at least a portion of the opposing surface of the acoustic absorber 122.

[0074] In some embodiments, the opposing surface of the acoustic absorber 122 may then be coupled to the outer casing 123 of the ultrasound sensor apparatus 100. The outer casing 123 may be made of a suitable metal or plastic.

[0075] The acoustic absorber 122 may act as a shock-absorbing seal between outer casing 123 and the second PCB 120b.

[0076] The channel 125 may be formed in each of the first PCB 120a, second PCB 120b, the acoustic absorber 122 layer, and the outer casing 123, thereby forming an acoustic port for the receiver element 120. The channel 125 allows for ultrasound waves to be directed from the outer surface of the outer casing 123 to the receiver element 120 (i.e. across the acoustic absorber 122 layer, and each of the first and second PCB 120a and 120b layers), such that the receiver element 120 is able to detect the ultrasound wave. Similarly, in the case where the element is a transmitter element 110, or where the element is a transceiver, the channel 125 allows for ultrasound waves to be directed from the transmitter element 110 (or transceiver element) to the outer surface of the outer casing 123 (i.e. past each of the first and second PCB 120a and 120b layers, and across the acoustic absorber 122 layer), and into the local environment.

[0077] The acoustically transparent material 121 layer, which extends across the channel 125, allows incoming ultrasound waves (or, in the case of a transmitterelement 110, outgoing ultrasound waves) to be transmitted whilst preventing dust, particulates, or moisture from reaching the first and second PCBs 120a and 120b, and the receiver element 120.

[0078] In some embodiments, the opening of the channel 125 at the outer surface of the outer casing 123 may be wider than the rest of the channel 125. This then allows ultrasound waves to more easily enter the channel 125 to be detected by the receiver element 120.

[0079] In some embodiments, one or both of the acoustically transparent material 121 and the acoustic absorber 122 may be formed only in the region immediately around the channel 125. Here, the acoustically transparent material 121 still extends across the channel 125.

[0080] It will be appreciated that the layers discussed above with reference to Figure 2 are an example construction of the ultrasound sensor apparatus 100, and that other layers may be employed, either additionally or alternatively, and that the layers described herein may implemented in a different order.

[0081] Where the ultrasound sensor apparatus 100 has a plurality of transmitters, Tx, arranged as a transmitter, Tx, array, the individual transmitters, Tx, of the array may be arranged in a variety of different configurations. In some embodiments, the plurality of transmitters, Tx, may be arranged and configured in order to achieve an omnidirectional propagation of transmitted signals. This then improves the directivity of the Tx array (e.g. both when transmissions are omnidirectional and when transmissions are beam steered).

[0082] Similarly, where the ultrasound sensor apparatus 100 has a plurality of receivers, Rx, arranged as a receiver, Rx, array, the individual receivers, Rx, of the array may be arranged in a variety of different configurations.

[0083] Figure 3 shows some example configurations (or arrangements) of the plurality of receivers in the receiver, Rx, array. It will be appreciated that the arrangements of Figure 3 may also be applied to transmitter, Tx, arrays or, where elements of the array are configured to operate as transceivers (i.e. both a transmitter and a receiver), Tx / Rx, array. In each example shown, the Rx and / or Tx arrays may be arranged as a phased array. In some embodiments, the Rx array may be a phased array.

[0084] As shown in arrangement A) of Figure 3, in some scenarios, the receivers of the Rx array may be arranged in a rectangular lattice (or grid).

[0085] As shown in arrangement B) of Figure 3, in some scenarios, the receivers of the Rx array may be arranged in a hexagonal lattice, thereby providing a more efficient use of the space available on that module of the ultrasound sensor apparatus 100.

[0086] As shown in arrangement C) of Figure 3, in some scenarios, the receivers of the Rx array may be arranged in a non-periodic arrangement. In the example shown in arrangement C), the receivers of the Rx array are arranged mathematically based on a Fibonacci sequence (for example, following the model for the pattern of florets in the head of a sunflower).

[0087] As shown in arrangement D) of Figure 3, in some scenarios, the receivers of the Rx array may be arranged in a non-periodic arrangement over multiple sub-arrays. In the example shown in arrangement D), the receivers in each sub-array of the Rx array are arranged mathematically based on a Fibonacci sequence.

[0088] It will be appreciated that, where the size and number of receivers in the Rx array in each example arrangement shown in Figure 3 may vary, this is simply for clarity, and the size and number of receivers in the Rx array may be chosen as needed for any given arrangement.

[0089] It will be appreciated that a Fibonacci sequence is one potential example of a non-periodic arrangement, and that other non-periodic arrangements may be implemented.

[0090] Where the receivers of the Rx array are arranged in a periodic manner (e.g. such as when the receivers of the Rx array are arranged in a rectangular lattice (or grid) or a hexagonal lattice (or grid), as shown in arrangements A) and B) of Figure 3), the received signal may include undesirable artifacts arising from that periodic arrangement, resulting in less accuracy in the imaging of the local environment, and / or the requirement to process and remove those artifacts from the received signal. Such artifacts may take the form of "lobes" in the resulting imaging data, arising as a result of the lines of symmetry in the periodic arrangement, and a non-optimal "pitch", A, between elements in the Rx array when operating at certain frequencies. Here, the "pitch", A, will be understood as the distance between each receiver element in the Rx array, as shown in the example arrangements A) and B) of Figure 3. It will be further understood that a periodic array may have more than one pitch value, depending on the number of axes of the given periodic array.

[0091] By comparison, by implementing the receivers of the Rx array in such a non-periodic arrangement, the distribution of different pitches across the array (example pitches Ai and A2 are shown in example arrangement C) in Figure 3), and the lack of lines of symmetry across the array, allows for more consistency in the resulting imaging data for any given set of frequencies. As a result, the ultrasound sensor apparatus 100 is able to ensure any artifacts in the received signal arising from the positioning of the receivers, and the pitch between the receivers, of the Rx array areminimised or removed all together regardless of the ultrasound frequencies currently being employed.

[0092] In some embodiments, a non-periodic random (or pseudo-random) arrangement of receivers of the Rx array is achieved through a random (or pseudo-random) distribution. Such a random distribution of elements in the Rx array provides an effective compromise across a range of different operating ultrasound frequencies, thereby also minimising or removing any artifacts in the received signals.

[0093] In some embodiments, the receivers of the Rx array may be arranged in a non-periodic, but still mathematically deterministic, arrangement. This then minimises or prevents undesirable frequency-dependent artifacts from being present in the received signal, whilst still ensuring the receivers of the Rx array are arranged in the mathematically deterministic and predicable manner (thereby increasing the consistency of the accuracy of the imaging across multiple ultrasound sensor apparatuses 100).

[0094] As shown in arrangement C) of Figure 3, one example of such a non-periodic arrangement is a Fibonacci arrangement, which provides a mathematically deterministic arrangement of the receivers of the Rx array that minimises or prevents artifacts arising in the received signal.

[0095] Arrangement D) shown in Figure 3 also shows such a non-periodic arrangement of receivers in the Rx array. However, in arrangement D), the receivers of the Rx array are separated into two sub-arrays: a dense inner array, and sparse outer array surrounding the dense inner array (each sub-array being delineated from the other by a dotted line). Whilst both of these sub-arrays employ a non-periodic Fibonacci arrangement in the same manner as in arrangement C), the average pitch for the denser inner sub-array is shorter than the average pitch of the sparser outer sub-array. This is illustrated by the example shorter pitch Ai for the denser inner sub-array, and the example larger pitch A2 of the sparser outer sub-array, shown in arrangement D) of Figure 3. This then results in a further minimisation or prevention of artifacts arising in the received signal.

[0096] Although arrangement D) of Figure 3 shows two separate sub-arrays, it will be appreciated that more sub-arrays may be included, each with a different density in the arrangement of receivers in the Rx array. It will also be appreciated that the density of receivers in the Rx array may gradually change from a dense inner arrangement to a sparser outer arrangement, rather than there being a clear boundary between subarrays as shown in arrangement D).

[0097] Figure 4 shows a flowchart of the method 1000 of operating the ultrasound sensor apparatus 100 according to some embodiments. That is to say, the elements,arrangements, and functionality discussed above may be applied to the steps of the flowchart shown in that figure.

[0098] Some of the steps shown in Figure 4 are optional steps (that is to say, not essential steps for implementing the method of the present application). Such optional steps are indicated as such with a dotted line. As discussed above, in some embodiments all the steps of the follow method 1000 may be carried out by modules disposed within the ultrasound sensor apparatus 100. Alternatively, some steps may be carried out by modules external to the ultrasound sensor apparatus 100.

[0099] Steps 1100 to 1600 may all occur during a single time period T. Alternatively, steps 1400 to 1600 may occur after the time period T, for example during a subsequent time period T+l, or during a processing period P, in which received signals are processed and local environment data is generated. It will be understood that, during operation of the ultrasound sensor apparatus 100, time periods may run consecutively.

[0100] The time period T may be of a predetermined length of time, or may be a period of time that is dynamically updated based upon received signals received by the Rx array of the ultrasound sensor apparatus 100 in a preceding time period.

[0101] At step 1100, one or more sets of ultrasound frequencies 150 are selected and encoded into one or more corresponding transmission signals 160.

[0102] Here, the set of ultrasound frequencies 150 may be selected from a range of ultrasound frequencies. For example, the range of ultrasound frequencies may extend in some embodiments from 20kHz the 80kHz, in some embodiments from 35kHz to 45kHz, or in some embodiments may have a broad range extending from 20kHz to 100kHz. The set of ultrasound frequencies 150 may be selected from the larger range of ultrasound frequencies in order to distinguish from the ultrasound frequencies encoded and transmitted in the transmission signal(s) of a preceding time period (where the reflections of such an earlier transmitted signal(s) may be received in a later time period). For example, the set of ultrasound frequencies 150 selected for each transmission signal 160 may be selected in order to distinguish from the sets of ultrasound frequencies selected for other transmission signals transmitted during the current time period T, or from other transmission signals transmitted over the last n number of time periods (where n is an integer). This approach allows for the precise transmission time of the originating transmission signal to be determined once the associated received signal is later decoded, enabling a subsequent time of flight calculation to be carried out as part of generating local environment data.

[0103] The set of ultrasound frequencies 150 may be encoded by means of, for example, one or more of amplitude modulation, frequency modulation, or phase-shift keying modulation. In some embodiments, the set of ultrasound frequencies 150 may beencoded (using, for example, one or more of amplitude modulation, frequency modulation, or phase-shift keying modulation) with a binary sequence, such as in the example shown in Figure 6.

[0104] It will be understood that the above examples are not limiting, and that a variety of different methods may be envisioned and employed to encode the set of ultrasound frequencies 150. Similarly, all of the methods of selecting a set of ultrasound frequencies, and encoding that set of ultrasound frequencies, described herein may be implemented separately or in combination, as required.

[0105] In some embodiments, the specific method of encoding the one or more sets of ultrasound frequencies 150 may be chosen to be different from any other method of encoding used for other transmissions during the current time period T, or any recent preceding time period. For example, the method of encoding the set of ultrasound frequencies 150 may be chosen to be different from any previously chosen method of encoding employed for the transmission of signals over the last n number of time periods (where n is an integer). For example, a different one of amplitude modulation, frequency modulation, or phase-shift keying (PSK) modulation may be employed in the encoding compared with previously transmitted signals, and / or a different sequence (e.g. a different binary sequence) may be encoded into the transmission signal 160.

[0106] It will be understood that varying the specific encoding of each set of frequencies 150 for each transmission signal 160 may be done as an alternative to, or in addition to, the varying of the set of ultrasound frequencies 150 selected for each transmission signal 160.

[0107] This then ensures that each encoded set of ultrasound frequencies 150 results in a transmission signal 160 that is different from any other transmission signal transmitted during the current time period T, and / or different from any other transmission signal transmitted during any of the preceding n time periods (where n is an integer). As such, received signals 170 can be decoded and identified as corresponding to a single recently transmitted transmission signal 170.

[0108] In some embodiments, the specific method of encoding the one or more sets of ultrasound frequencies 150 may be selected based upon local environment data 180 generated from a previously received signal 170. For example, it may be determined from local environment data 180 generated based on a previously received signal 170 that a particular method of encoding is preferential over other encoding methods as a result of current factors associated with the local environment. For example, an aspect of the current local environment (e.g. the current weather or the materials used in the local environment) may be such that a particular method of encoding results in a transmission signal 160 that has an improved signal strength in the correspondingreceived signal 170. In such scenarios, the specific method of encoding may be dynamically changed to improve the quality of the local environment data 180 that is generated, or improve the sensitivity of the Rx array of the ultrasound sensor apparatus 100.

[0109] In some embodiments, the specific method of encoding may be selected dynamically in response to local environment data received from other sources. For example, the ultrasound sensor apparatus 100 may include, or receive data from, one or more microphones that monitor environmental background noise within the audible range (i.e. approximately 20Hz to 20kHz). In such scenarios, the selection of the set of ultrasound frequencies 150 and / or the method of encoding that selected set of ultrasound frequencies 150 may be based on the amount and nature of the current environmental background noise (e.g. in order to find a "quiet" part of the spectrum).

[0110] Modulation techniques such as amplitude modulation, frequency modulation, and phase-shift keying modulation also provide benefits such as improved signal to noise, increased framerate, and range flexibility, in addition to the encoding discussed above.

[0111] As discussed above, in some embodiments the set of ultrasound frequencies 150 may be encoded in the manner discussed above by a control module 140 of the ultrasound sensor apparatus 100.

[0112] At step 1200, the one or more encoded transmission signals 160 are transmitted into the local environment. In some embodiments, one or more transmitters of a transmitter, Tx, array of the ultrasound sensor apparatus 100 may transmit the transmission signals 160 into the local environment. In some embodiments, the transmission signals 160 are transmitted as a pulse.

[0113] In some embodiments, and as discussed above, the one or more transmitters of the transmitter, Tx, array may function as part of a transceiver of the ultrasound sensor apparatus 100.

[0114] Furthermore, and as discussed above, in some embodiments the one or more transmitters of the Tx array may transmit the transmission signal 160 in response to receiving a signal from a driver module 130 of the ultrasound sensor apparatus 100. Here, the driver module 130 of the ultrasound sensor apparatus 100 may drive the Tx array to transmit the one or more transmission signals 160, and may operate either by providing the same signal to each of the transmitters in the Tx array, a different signal to each of the transmitters in the Tx array, or a different signal to each of a series of subgroups of transmitters in the Tx array, as discussed above.

[0115] As discussed above, in embodiments where the ultrasound sensor apparatus 100 comprises multiple transmitters in a transmitter, Tx, array, that Tx array may beoperated as a phased array, and such that the one or more transmission signals 160 are transmitted by the transmitters of the Tx array in a directionally steered manner (i.e. "beam steering"). This then allows for improved directivity of the one or more transmitted signals 160.

[0116] In some embodiments, the Tx array may employ beamforming (e.g. delay-and- sum beamforming) when transmitting transmission signal 160 in order to improve signal to noise or to probe a particular direction.

[0117] At step 1300, a plurality of receivers of a receiver, Rx, array of the ultrasound sensor apparatus 100 receive at least one received signal 170. The at least one received signal 170 may represent a reflection in the local environment of a transmission signal 160 that was transmitted during a time period that preceded the current time period T.

[0118] In some embodiments, and as discussed above, the one or more receivers of the receiver, Rx, array may function as part of a transceiver of the ultrasound sensor apparatus 100. As discussed above with respect to the Tx array, beam steering may be employed in the Rx array to improve directivity (e.g. in order to concentrate on a particular area or region of interest in the local environment).

[0119] In some embodiments, the Rx array may employ beamforming (e.g. delay-and- sum beamforming) when receiving received signals 170 in order to improve signal to noise or to probe a particular direction.

[0120] In some embodiments, the received signal 170 may be passed to the processing module 145 of the ultrasound sensor apparatus 100 for decoding in the manner discussed below with reference to step 1400. In other embodiments, the received signal 170 may be outputted to an external system for decoding.

[0121] At step 1400, the at least one received signal 170 is decoded to ascertain whether the at least one received signal is a reflection from the local environment of a corresponding at least one transmission signal 160 transmitted during a time period preceding the current time period T.

[0122] That is to say, by attempting to decode the one or more received signal 170, it can be determined if the one or more received signal 170 is encoded in the same manner as a preceding one or more transmission signal 160.

[0123] For example, it may be determined that the received signal 170 comprises the same set of ultrasound frequencies 150 that were selected for a preceding transmission signal 160, and / or has undergone the same encoding procedure (or method of encoding) of a preceding transmission signal 160 (e.g. the received signal 170 comprises the same binary sequence encoded into an earlier transmitted transmission signal 160 and / or has been encoded using, for example phase-shift keying).

[0124] If it is determined that this is the case, it can be concluded that the one or more received signal 170 is a transmission signal 160 that was transmitted during a time period preceding the current time period T, where that earlier transmission signal 160 has been reflected off one or more surfaces of the local environment before being received as the received signal 170.

[0125] In some embodiments, decoding the received signal 170 may include reversing the encoding method used for the preceding transmission signals. For example, where one of amplitude modulation, frequency modulation, or phase-shift keying modulation was used for previously transmitted transmission signals, that same method may be used to decode the received signal 170.

[0126] In some embodiments where a different specific method of encoding has been used for each previously transmitted transmission signals (which may be over the current time period T or over n preceding time periods), all previously used specific methods of encoding may be employed to decode the received signal 170. This may be done either consecutively or concurrently, until the decoded received signal 170 can be matched to a corresponding previously transmitted transmission signal 160.

[0127] As discussed above, in some embodiments, the processing module 145 of the ultrasound sensor apparatus 100 decodes the at least one received signal 170 to ascertain whether the at least one received signal is a reflection from the local environment of a corresponding at least one transmission signal 160 previously transmitted during the current time period T, or during a time period preceding the current time period T. In other embodiments, the received signal 170 may be output to a separate system for decoding.

[0128] At step 1500, local environment data 180 is generated from the decoded at least one received signal 170. The local environment data 180 includes spatial data relating to at least a portion of the local environment around the ultrasound sensor apparatus 100. Such spatial data may include the locations at which a transmitted transmission signal 160 is determined to have been reflected back towards the Rx array and received as a received signal 170. For example, the local environment data 180 may take the form of a heat map of at least a part of the local environment representing the density of distributions of such scattering locations. As a further example, the local environment data 180 may take the form of a point cloud of at least a part of the local environment showing the determined scattering locations. As a further example, the local environment data 180 may take the form of a list of coordinates in two or three dimensions, each set of coordinates representing a determined scattering point in the local environment. The local environment data 180 may take the form of any other spatial representation or spatial data relating to at least a part of the local environment.

[0129] For example, by matching a decoded at least one received signal 170 to an encoded one or more transmission signal 160 transmitted during a preceding time period T, data describing a distance can be ascertained based on a time-of- flight calculation, and included in the generated local environment data 180. That is to say, an assumed point of reflection can be ascertained based upon the time of transmission of the earlier transmission signal 160 and the time of receipt of the received signal 170 (taken in combination with an inferred propagation speed of the transmitted ultrasound signal through the local environment, using known, measured, or preset air temperature values).

[0130] A further example of local environment data 180 that may be generated based on the decoded at least one received signal 170 may be data describing a direction from which the at least one received signal 170 was received (when also considering the known geometry of the array). For example, the plurality of receivers of the Rx array of the ultrasound sensor apparatus 100 may be configured to operate as a phased array, so that the direction from which the received signal 170 is received (i.e. the direction of the associated scatterer) can be determined.

[0131] An additional example of local environment data 180 that may be generated include data relating to a Doppler shift in the received signal 170 compared with the associated earlier transmission signal 160, such that speed or velocity data can be generated.

[0132] The local environment data 180 may therefore comprise spatial data relating to at least one scatterer in the local environment around the ultrasound sensor apparatus 100. Such spatial data may include data regarding, for example, distance to, direction to, speed of, and / or velocity of an associated scatterer (i.e. an object) in the local environment.

[0133] The local environment data 180 may be generated from a single received signal 170, or may be generated from a plurality of recently received signals 170 (e.g. all the signals received during the current time period T). The local environment data 180 may be generated from all signals received over a particular period of time (e.g. all signals received during one or more time periods T).

[0134] In some embodiments, received signals 170 may be processed, and local environment data 180 may be generated, once during a given processing period P. For example, all received signals 170 that are decoded during a processing period P may be used to generate one set of local environment data 180 for that processing period P, before a new set of local environment data 180 is then generated in a subsequent processing period P for all signals received during that subsequent processing period P.

[0135] The term "local environment data" 180 may alternatively be referred to as "spatial data", "local spatial data", or "spatial environment data".

[0136] In some embodiments, the processing module 145 of the ultrasound sensor apparatus 100 generates the local environment data 180 based on the decoded at least one received signal 170. In other embodiments, a separate system generates the local environment data 180 based on the decoded at least one received signal 170. For example, and as discussed above, the at least one received signal 170 may be output to a separate system for decoding, before the same separate system or another separate system generates the local environment data 180 based on the decoded at least one received signal 170.

[0137] At step 1600, an image from the local environment is generated based on the local environment data 180, and / or objects in the local environment may be identified based on the local environment data 180.

[0138] For example, where the local environment data 180 includes spatial data indicating the presence of a scatterer located at a certain distance and direction from the plurality of receivers of the receiver, Rx, array of the ultrasound sensor apparatus 100, then this can be used to generate an image of the local environment including that scatterer.

[0139] In some embodiments, the image may be limited to only a portion of the local environment, where that portion of the local environment has a particular significance. For example, where the ultrasound sensor apparatus 100 is installed on a vehicle, only parts of the local environment of particular significance to the present situation may be imaged. As a further example, during a parking manoeuvre only areas around the vehicle relevant to the manoeuvre may be imaged (e.g. directly in front of the vehicle, directly behind the vehicle, other cars, pedestrians, or fixed objects such as parking bollards).

[0140] In some embodiments, the processing module 145 of the ultrasound sensor apparatus 100 generates a two or three-dimensional image of at least a portion of the local environment or, in some embodiments, of an object within the local environment, based on the generated local environment data 180. In some embodiments, the processing module 145 may identify an object in the local environment based on the local environment data 180.

[0141] In other embodiments, the generated local environment data 180 may be output to a separate system, which then generates the two or three-dimensional image of at least a portion of the local environment (or, in some embodiments, of an object within the local environment, or identify such an object), based on that generated local environment data 180. In such embodiments, such a separate system may be the same,or different, system that decoded the at least one received signal 170 and generated the local environment data 180.

[0142] In some embodiments, the processing module 145 may aggregate local environment data 180 generated by multiple separate ultrasound sensor apparatuses 100 to generate imagery of the local environment. For example, multiple separate ultrasound sensor apparatuses 100 may receive separate received signals and process those received signals as discussed above with reference to steps 1100 to 1600 of Figure 4. The resulting generated local environment data 180 from each separate ultrasound sensor apparatus 100 may then be aggregated with other local environment data 180 to generate the image of the local environment.

[0143] The multiple separate ultrasound sensor apparatuses 100 may be distributed around the local environment, such that any image (i.e. a two or three-dimensional image) generated from spatial data (i.e. local environment data) aggregated from each of those multiple separate ultrasound sensor apparatuses 100 then benefits from the received signals (and therefore the associated generated spatial data) being received from multiple angles.

[0144] For example, the multiple separate ultrasound sensor apparatuses 100 may be installed at various points on the body of a vehicle, or may be installed around a particular static space (e.g. a parking space), so that the images generated (i.e. two or three-dimensional images) include a more detailed image of at least a portion of the local environment (or object located in the local environment).

[0145] Alternatively or additionally, in some embodiments the generated local environment data 180 may be aggregated with data from other sensor systems employing other sensor modalities, for example radar, lidar, infrared, optical cameras, or microphones. In such scenarios, the resulting image generated may be more detailed or the accuracy of the image may be improved.

[0146] In some embodiments, the image that is generated may be based upon generated local environment data 180 from multiple received signals. For example, where each received signal 170 may correspond to a previously transmitted transmission signal 160 (for example, a transmission signal 160 that was transmitted during a preceding time period), the generated local environment data 180 associated with each previously transmitted transmission signal 160 may be aggregated in order to improve the quality and / or accuracy of the resulting image that is generated.

[0147] In some embodiments, the ultrasound sensor apparatus 100 may output the generated local environment data 180 to an external system in step 1950, either as an alternative to or in addition to the processing discussed above in step 1900.

[0148] Here, the generated local environment data 180 may be output to an external system or electronics device such as, but not limited to, a cloud service, one or more computers, an embedded vehicular computer, a tablet, and / or a smartphone. This may be achieved using the communications module 135 discussed above.

[0149] The external system or electronics device may then aggregate and / or perform processing on the local environment data 180 (for example, to generate an image of at least a portion of the local environment, or of an object located in the local environment, or to identify such an object).

[0150] When the generated local environment data 180 is outputted, the data may be compressed to reduce data bandwidth usage (i.e. when transmitted to an external system). The method of data compression may depend upon the current operating mode of the ultrasound sensor apparatus 100 (e.g. whether the data is intended for generating a one-dimensional, two-dimensional, or three-dimensional image). In some embodiments, the specific method of compression may be selected based on the amount of data generated. Other factors, such as image quality requirements, may also be considered when determining the method of data compression. The external system or electronics device may then decompress the compressed local environment data 180 prior to any processing.

[0151] In some embodiments, the image generated by the ultrasound sensor apparatus 100 may be outputted to an external system or electronic device, instead of the local environment data 180 (compressed or uncompressed). This may be achieved using the communications module 135 discussed above.

[0152] In addition to the steps discussed above, in some embodiments the steps shown in Figure 4 may additionally include optional steps 1050, 1150, 1250, and 1450.

[0153] At step 1050, two or more regions in the local environment are defined based upon selected distances from the Rx array of the ultrasound sensor apparatus 100. Here, distances from the Rx array of the ultrasound sensor apparatus 100 within the local environment may be chosen and employed to separate the local environment into a plurality of regions. Each region can then be probed separately and concurrently, providing improved imaging performance in those regions of interest.

[0154] In some embodiments, each region is defined as being a range of distances from the ultrasound sensor apparatus 100 (where each region does not overlap with other regions). Figure 5 shows an example approach to defining such regions.

[0155] For example, and as shown in Figure 5, a first region 200a may then be defined as the area of the local environment that is within the first distance dl from the ultrasound sensor apparatus 100. Depending on the distribution of the receivers of the Tx and / or Rx array of the ultrasound sensor apparatus 100, this may for example takethe form of an arc (or, in some scenarios, a ring) in the local environment, with the ultrasound sensor apparatus 100 at the centre. Then, a second region 200b may be defined as the area of the local environment that is greater than the first distance dl from the ultrasound sensor apparatus 100, but less than a second distance d2 from the ultrasound sensor apparatus 100. This then forms a series of concentric arcs (or, in some scenarios, rings), with the ultrasound sensor apparatus 100 in the centre.

[0156] It will be appreciated that further regions may be defined in a similar manner to the definition of the first region 200a and second region 200b shown in Figure 5, and the present disclosure is not limited in terms of the number of regions defined, the specific manner of defining those regions, or the resulting shape of those regions (e.g. arc, ring, or otherwise).

[0157] In some embodiments, the distances (e.g. the first distance dl and the second distance d2) for defining regions may be predetermined distances. For example, the distances for defining regions may be selected based upon local environment data 180 generated based on a previously received signal 170. For example, generated local environment data 180 from a previously received signal 170 may indicate that an area of the local environment of particular interest is located a given distance away from the ultrasound sensor apparatus 100. As such, a first distance dl and a second distance d2 may be selected based upon this indication, such that a first region 200a and a second region 200b maybe defined such that the area of interest falls within the second region 200b. the second region 200b can then be specifically probed to provide improved imagery of that area of interest.

[0158] Then, in step 1150, the selecting and encoding of the at least one set of ultrasound frequencies 150 may include selecting and encoding a set of ultrasound frequencies 150 for each region that has been defined, resulting in a transmission signal 160 for each region.

[0159] Here, the encoding of the set of ultrasound frequencies 150 for each region may be based on the selected distances that define that region. For example, a separate set of frequencies may be selected for each region such that any received signals can be distinguished by the region in which a reflection has occurred.

[0160] For example, where a first region 200a and a second region 200b have been defined based on an indication from generated local environment data 180 from a previously received signal 170 that an area of interest is located in the second region 200b, a particular set of frequencies may be selected for the second region 200b in order to probe the area located in the second region 200b. This selection may be made based upon the known propagation speed and / or rate of attenuation of that set of ultrasound frequencies for the distances falling within the second region 200b. Thearea located in the second region 200b can then be imaged more efficiently and to a higher level of accuracy.

[0161] This also allows for the repetition rate of the transmission signals 160 intended for each region to be tailored accordingly. For example, transmission signals that are intended to probe the first region 200a (which is closer to the ultrasound sensor apparatus 100) may have a shorter repetition rate compared with transmission signals that are intended to probe the second region 200b (which is further from the ultrasound sensor apparatus 100).

[0162] Alternatively or additionally, the transmission signals 160 may be encoded differently depending on the region they are intended to probe. For example, transmission signals 160 intended for probing the first region 200a may be encoded using one of amplitude modulation, frequency modulation, or phase-shift keying modulation, and transmission signals 160 intended for probing the second region 200b may be encoded using another one of amplitude modulation, frequency modulation, or phase-shift keying modulation, different to the method used for transmission signals 160 intended for the first region 200a.

[0163] This allows for multiple transmission signals 160 to be transmitted and multiple received signals 170 to be received in a given time period T, such that the Tx / Rx array may be triggered multiple times within the time required for the ultrasounds signals to travel the distance to and from a scatterer located within a defined region.

[0164] It is noted that these discussed approaches to defining and probing regions of the local environment may be employed concurrently with, and in addition to, other approaches discussed above in which the frequency selection and / or encoding of transmission signals is varied during a given time period T.

[0165] In some embodiments, this approach may be employed to select an appropriate length of the time period T.

[0166] In some embodiments, a first set of ultrasound frequencies 150a may be selected and encoded in a first time period T_1 in order to probe the first region 200a. Then, during a second time period T_2, a second set of frequencies 150b may be selected and encoded, differently to the first set of ultrasound frequenciesl50a, in order to probe the second region 200b. Here, the selection and encoding in the first time period T_1 and the second time period T_2 may vary based on one or both of the selection of the set of frequencies or the specific method of encoding used. In some embodiments, the first time period T_1 and the second time period T_2 occur during a single time period T. Alternatively, the first time period T_1 and the second time period T_2 occur during a successive time periods T and T+l.

[0167] As a result, all transmission signals 160 transmitted during the first time period T_1 are intended to probe the first region 200a, and all transmission signals 160 transmitted during the second time period T_2 are intended to probe the second region 200b. Any signals received in subsequent time periods can then be distinguished by the region in which a reflection has occurred, since the choice of set of frequencies selected and / or the method of encoding is specific to a known time period (e.g. either the first time period T_1 or the second time period T_2).

[0168] Then, in step 1250, the transmission signal 160 for each region is transmitted by the one or more transmitters of the ultrasound sensor apparatus 100. This may occur simultaneously (i.e. when multiple transmitters in a Tx array is employed), or sequentially over the current time period T (or, in some embodiments, over successive time periods T and T+l).

[0169] Then, in step 1450, it is determined whether the received signal 170 corresponds to the transmission signal 160 for one of the regions in the local environment. As in step 1400 above, this may be achieved by decoding the received signal 170 and determining if the decoded received signal corresponds to the transmitted signal for one of the regions. Where multiple transmission signals 160 have been used to probe multiple regions, and where different sets of frequencies have been selected for different regions, frequency filtering may be employed to separate multiple received signals 170 from multiple regions.

[0170] It will be understood that optional steps 1150, 1250, and 1450 discussed above may form part of respective steps 1100, 1200, and 1400, as shown in Figure 4.

[0171] Figure 6 shows some example plots of the elements of a transmission signal 160 and those of a received signal 170 that corresponds to that transmission signal 160. Here, a binary sequence (represented in plot A)) is encoded into a set of selected ultrasound frequencies (represented in plot B)) using phase-shift keying (PSK).

[0172] It is highlighted that the set of selected ultrasound frequencies of plot B) of Figure 6 is shown as a continuous sinusoidal wave only for clarity, and it will be appreciated that the form of the plot shown in plot B) of that Figure is non-limiting (as is the form of the other plots of Figure 6).

[0173] The encoded set of ultrasound frequencies is shown in plot C) of Figure 6. Here, and as stated above, the set of ultrasound frequencies have been encoded with the binary sequence of plot A), using PSK. As stated above, it will be appreciated that other methods of encoding may be employed, and the use of a binary sequence and PSK in the example of Figure 6 is one possible approach to encoding.

[0174] The encoded set of ultrasound frequencies shown in plot C) is then transmitted by a transmitter of the ultrasound sensor apparatus 100, or by a Tx array comprising aplurality of transmitters, into the local environment as a transmission signal 160. Whilst the example of plot C) shows a continuous signal being transmitted, it will be appreciated that transmission signals 160 may be transmitted in other manner (e.g. as a pulse).

[0175] The Rx array then receives a received signal 170 shown in plot D). Here, the received signal 170 may include a degree of noise, distortion, and amplitude changes compared with the preceding transmission signal 160. It will be appreciated that whilst the example plot D) shows the amplitude of the received signal 170 being the same as the preceding transmission signal 160 of plot C), this is only for clarity.

[0176] The received signal in example plot D) is then decoded to ascertain whether the received signal 170 corresponds to the preceding transmission signal 160. In this regard, PSK may again be employed in a reverse manner to the encoding of the transmission signal 170 shown in example plot C).

[0177] Then, in example plot E), it can be seen that the received signal 170, once decoded, comprises the same binary sequence as that shown in plot A) that was used to encode the earlier set of ultrasound frequencies of plot B) into the transmission signal 160 of plot C). In this regard, the specific sequence encoded into the transmission signal 160 is chosen such that that sequence is substantially preserved in the received signal 170, despite the present of noise, distortion, or amplitude changes.

[0178] As such, it can be ascertained that the received signal 170 corresponds to the earlier transmitted signal 160, and local environment data 180 may then be generated based on the received signal 170 (for example, the distance and direction to a scatterer in the local environment as be ascertained, using time-of-flight calculations, inferred propagation speeds, the geometry of the Rx array, and / or other factors).

[0179] Figure 7 shows an example of an image that may be generated from local environment data 180 generated based on one or more decoded received signals 170.

[0180] In this example, the local environment data 180 comprises a plurality of spatial locations in the local environment around the ultrasound sensor apparatus 100 from which one or more signals (i.e. transmission signals 160) transmitted by the Tx array have been reflected and received (i.e. as received signals 170). These locations in the local environment data 180 can then be processed to indicate the presence of objects within the local environment.

[0181] In the example image shown in Figure 7, it can be ascertained that six objects are located in the local environment in front of the Rx (or Tx / Rx) array (shown in Figure 7 as a sphere for clarity).

[0182] As can be seen from the example image in Figure 7, one or more objects in the local environment can be imaged, including the location of those one or more objectsin the local environment. In some embodiments, the accuracy and resolution of the ultrasound sensor apparatus may be sufficient that the size and shape of the object in the local environment can be imaged (e.g. in the example image of Figure 7, the objects may be identified as six columns). This then provides a high level of detail of the object for a user and system monitoring the ultrasound sensor apparatus 100. For example, where the ultrasound sensor apparatus 100 is installed on a vehicle, the apparatus may be able to detect an object in the local environment around the vehicle, and also provide data regarding the size and shape of that object, which can then be used to generate an image of that object.

[0183] In some embodiments, the local environment data 180 may be provided to a specialist software package comprising an imaging algorithm, which then generates an image based on that local environment data 180. This software package may be installed on a processing module 145 such as that discussed above.

[0184] In some embodiments, the processing of the local environment data 180, and the generation of an image, may be carried out in the frequency domain, thereby offering a greatly improved speed of computation, with a decrease in precision that scales with range.

[0185] The various methods described herein may be used in isolation to provide an accurate ultrasound sensor package. Furthermore, the various methods described herein may be used in combination to provide a more accurate ultrasound sensor package. For example, frequency domain beamforming, such as that discussed above, may be carried out and the results averaged together. Then, regions of the local environment may be defined to allow tailored probing of those regions above the current level of noise. Then, delay-and-sum beamforming may be applied to each region to produce a final imaging result with high resolution and precision.

[0186] In some embodiments, the one or more transmission signals 160 may include a unique ID of the ultrasound sensor apparatus 100. For example, where the ultrasound sensor apparatus 100 is installed on a vehicle, each transmission signal 160 may include an ID identifying that vehicle, so that vehicle is able to distinguish received signals 170 that correspond to that vehicle from those of other vehicles operating other ultrasound sensor apparatuses. This then reduces the likelihood of the ultrasound sensor apparatus 100 incorrectly associating a signal received from the ultrasound sensor apparatus of another vehicle or system with a previously transmitted signal.

[0187] A unique ID may be encoded into each transmission signal 160 by employing, for example, phase-shift keying, quadrature phase-shift keying modulation, frequency shift keying, or amplitude shift keying, although it will be understood that other potential methods of encoding an ID into the transmission signals 160 may be used.

[0188] Such an ID may be pre-set for each ultrasound sensor apparatus 100, and may be encoded into each transmission signal 160 by the control module 140 prior to transmission.

[0189] Such an ID may take the form of a binary sequence, such as that shown in example plots A) and E) of Figure 6, or may be implemented separately and in addition to the sequence shown in those example plots.

[0190] The above discussed method may be performed using a computer system or similar computational resource, or system comprising one or more processors and a non-transitory memory storing one or more programs configured to execute the method. Likewise, a non-transitory computer readable storage medium may store one or more programs that comprise instructions that, when executed, carry out the methods described herein.

[0191] Whilst the above ultrasound sensor apparatus 100 is discussed in the context of operating in air, it will be appreciated that the approaches discussed herein may also be employed in other suitable mediums (e.g. other gaseous environments).

[0192] Whilst certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the application. Indeed, the novel devices, and methods described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the devices, methods and products described herein may be made without departing from the scope of the present application. The word "comprising" can mean "including" or "consisting of" and therefore does not exclude the presence of elements or steps other than those listed in any claim or the specification as a whole. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope of the application.

Claims

CLAIMS1. A method of ultrasound sensing in air, the method comprising: during each of a plurality time periods: encoding at least one set of ultrasound frequencies from a plurality of ultrasound frequencies into at least one transmission signal; transmitting the at least one transmission signal by one or more transmitters of an ultrasound sensor apparatus located in a local environment; receiving, by a plurality of receivers of the ultrasound sensor apparatus, at least one received signal; determining that the at least one received signal is a reflection of the corresponding at least one transmission signal from the local environment by decoding the at least one received signal; and generating local environment data based on the decoded at least one received signal; generating an image of at least a portion of the local environment based on the local environment data.

2. The method of claim 1, wherein the encoding of the at least one set of ultrasound frequencies into the at least one transmission signal comprises encoding the at least one set of ultrasound frequencies using one or more of amplitude modulation, frequency modulation, or phase-shift modulation.

3. The method of claims 1 or 2, wherein: for at least one of the plurality of time periods, the encoding of the at least one set of ultrasound frequencies is based upon the local environment data generated based on at least one signal received during a preceding time period.

4. The method of any preceding claim, wherein: for each of the plurality of time periods, the encoding of the at least one set of ultrasound frequencies is different to the encoding of the at least one set of ultrasound frequencies of a preceding time period, and / or for each of the plurality of time periods, the encoding of the at least one set of ultrasound frequencies is different to the encoding of any other of the at least one set of ultrasound frequencies of that time period.

5. The method of any preceding claim, wherein the image of at least a portion of the local environment is a three-dimensional image.

6. The method of any preceding claim, wherein the plurality of receivers receives the at least one received signal when operating as a phased array.

7. The method of any preceding claim, wherein the method further comprises at least one of: determining the location of an object in the local environment based on the local environment data; and generating an image of the object based on the local environment data.

8. The method of any preceding claim, wherein the method further comprises: defining a first region and a second region in the local environment, the first region being defined being less than a first distance from the plurality of receivers of the ultrasound sensor apparatus located in the local environment, and the second region being more than the first distance and less than a second distance from the plurality of receivers of the ultrasound sensor apparatus located in the local environment; and wherein: the encoding of the at least one set of ultrasound frequencies comprises encoding a set of ultrasound frequencies from the plurality of ultrasound frequencies into a transmission signal for each region, wherein the encoding of the set of ultrasound frequencies for the first region is based on the first distance and the encoding of the set of ultrasound frequencies for the second region is based on second distance; the transmitting of the at least one transmission signal comprises transmitting the transmission signal for each of the first and second regions; and the determining comprises determining that at least one received signal is a reflection of a transmission signal for the first region or the second region of the local environment by decoding the at least one received signal.

9. The method of any preceding claim, wherein the plurality of receivers include the one or more transmitters; andwherein the at least one receiver of the plurality of receivers that includes the one or more transmitters is configured to operate as a transceiver.

10. An ultrasound sensor apparatus for ultrasound sensing in air, the ultrasound sensor apparatus comprising: at least one transmitter; a plurality of receivers; and a driver module configured to drive the at least one transmitter and the plurality of receivers; wherein the plurality of receivers are arranged in a non-periodic arrangement.

11. The ultrasound sensor apparatus of claim 10, wherein the ultrasound sensor apparatus further comprises: a communications module configured to transmit signal data associated with signals received by the plurality of receivers.

12. The ultrasound transceiver of claim 10, wherein the ultrasound sensor apparatus further comprises: a control module, wherein the control module is configured to: encode one or more sets of ultrasound frequencies into one or more transmission signals for transmission by the at least one transmitter; and decode received signals, received by the plurality of receivers; and generate local environment data based on the decoded signals; a processing module, wherein the processing module is configured to: generate, using the local environment data, an image of at least a portion of the local environment around the sensor apparatus.

13. The ultrasound transceiver of any of claims 10 to 12, wherein the non-periodic arrangement of the plurality of receivers is a Fibonacci arrangement.

14. The ultrasound transceiver of any of claims 10 to 13, wherein the plurality of receivers is configured to be operated as a phased array.

15. The ultrasound transceiver of any of claims 10 to 14, wherein the at least one transmitter and the plurality of receivers are arranged in a stack.

16. The ultrasound sensor apparatus of any of claims 10 to 15, wherein at least one of the plurality of receivers is mounted on a plurality of layers, the plurality of layers comprising a channel extending from the at least one of the plurality of receivers to an outer surface of an outer casing of the ultrasound sensor apparatus; wherein the plurality of layers further comprises an acoustically transparent layer extending across the channel, and optionally; wherein the plurality of layers further comprises an acoustically absorbing layer.

17. The ultrasound sensor apparatus of any of claims 10 to 16, wherein the plurality of receivers include the at least one transmitter; and wherein the at least one receiver of the plurality of receivers that includes the at least one transmitter is configured to operate as a transceiver.

18. The ultrasound sensor apparatus of any of claims 10 to 17, wherein the ultrasound sensor apparatus is configured to carry out any of the methods of claims 1 to 9.

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