Patent Application
20210111483
The present invention relates, generally, to micro-antenna arrays and, more particularly, to micro-antenna arrays implemented in surface-penetrating radar (SPR) systems.
Modern wireless communication systems generally feature small-profile, lightweight, and high-gain antennas with simple structures to assure reliability, mobility, and high efficiency. Conventionally, compact antennas rely on electromagnetic (EM) wave resonance; as a result, the sizes of conventional antennas are comparable to the EM wavelength (typically greater than one-tenth of the EM wavelength). Applications such as vehicle localization can depend critically on the size of the antenna. Ultimately, however, antenna miniaturization is limited by considerations of antenna performance, material cost, and viable wavelengths.
A recently developed technique tailors antennas to acoustic wave resonance. For example, acoustically actuated nanomechanical magnetoelectric (ME) antennas with a suspended ferromagnetic/piezoelectric thin-film heterostructure have been proposed to receive and transmit EM waves at their acoustic resonance frequencies via the ME effect. While this technique significantly reduces antenna size by one or two orders of magnitude compared to electromagnetically actuated antennas, ME antennas exhibit a high quality factor (“high Q”), which leads to ringing as well as high sensitivity of the input impedances to small changes in the frequency. The resulting performance degradation limits the utility of these antennas in applications involving wide bandwidths and noisy environments.
Accordingly, there is a need for antennas having sizes comparable to that of the acoustically actuated ME antennas while mitigating the high-Q problems of the acoustically actuated ME antennas.
Embodiments of the present invention provide a micro-antenna array that may have an ultra-compact size (e.g., dimensions comparable to those of a conventional microchip) without exhibiting the high-Q problems that have characterized acoustically-actuated ME antennas. In various embodiments, a micro-antenna array includes multiple micro-antenna elements; each element is an acoustically actuated ultra-compact nanoelectromechanical system (NEMS) ME antenna having a suspended ferromagnetic/piezoelectric thin-film heterostructure and capable of operating at a peak frequency between 30 Hz and 3 GHz. To mitigate the effects of high Q, each micro-antenna element is designed (in terms of material and/or configuration (e.g., size or shape)) to operate within a relatively narrow bandwidth (e.g., 2 kHz), but the frequency bands (or frequency ranges) of the elements in the micro-antenna array collectively span a wide spectral region (e.g., from 10 kHz to 10 GHz). In addition, the peak operating frequencies associated with adjacent micro-antenna elements may have a stepped-frequency difference. The operating frequency bands of the micro-antenna elements may overlap one another or may abut one another.
In one embodiment, the micro-antenna elements in the array are operated as a group such that the entire array effectively acts as a single broadband transmitter and/or receiver. Alternatively, the micro-antenna elements in the array may be grouped into multiple series; each series is independently controlled to transmit and/or receive signals within a frequency range collectively determined by the micro-antenna elements in the series. In some embodiments, each micro-antenna element in the array is independently controlled to transmit and/or receive signals in its associated frequency range. Regardless of whether the micro-antenna elements are operated in a grouped or individual manner, the signals transmitted and/or received thereby may be computationally combined to span the broadband spectral frequency range.
In various embodiments, one or more micro-antenna arrays are implemented in an SPR system affixed to a vehicle and operated to acquire road surface and/or subsurface information of the terrain conditions and/or locational information of the vehicle. When multiple micro-antenna arrays are employed, anomalies in the underlying terrain may be detected by comparing the signals received by the arrays. The groupings may be two-dimensional (2D) and/or three-dimensional (3D) configurations that enable multiple inputs and/or output measurements. This can also be achieved by creating a steering beam from one micro-antenna array that can focus in different directions/locations, e.g., by operating the micro-antennas as a phased array. In some embodiments, separate sets of micro-antenna arrays are distributed around the vehicle (e.g., one array in the front of the vehicle and another one in the rear of the vehicle). The front array may map underlying and surface terrain and, based on the map, the rear array may record and register data to the front-array data, thereby revealing the state information (e.g., steering, orientation, velocity, pose, acceleration and/or deceleration) of the vehicle.
Accordingly, in one aspect, the invention pertains to a system for navigating a vehicle on a terrain. In various embodiments, the system includes an SPR system having one or more micro-antenna arrays for acquiring real-time SPR information associated with the vehicle, and one or more controllers configured to, based at least in part on the acquired real-time SPR information, determine information associated with the terrain and/or the vehicle. The micro-antenna array(s) may include multiple micro-antenna elements each being configured to operate at a frequency range, the frequency ranges of the micro-antenna elements collectively spanning a full frequency range greater than the frequency range of an individual one of the micro-antenna elements.
In various embodiments, each of the micro-antenna elements includes an acoustically actuated ultra-compact nanoelectromechanical system (NEMS) ME antenna and has a suspended ferromagnetic/piezoelectric thin-film heterostructure. In addition, each of the micro-antenna elements may have dimensions comparable to those of a conventional microchip. In one implementation, the full frequency range corresponds to frequencies between 10 kHz and 10 GHz. In some embodiments, each micro-antenna element has a peak operating frequency, and the peak operating frequencies associated with adjacent micro-antenna elements have a stepped-frequency difference. The frequency ranges of adjacent micro-antenna elements may overlap each other. Alternatively, the frequency ranges of adjacent micro-antenna elements may abut each other. In one embodiment, the micro-antenna elements are operable over approximately 2 kHz.
In some embodiments, the SPR system includes multiple micro-antenna arrays, each configured to focus at a different region. In addition, the controller may be further configured to compare the SPR information received by the micro-antenna arrays; and determine anomalies in the terrain condition associated with one or more of the regions. In addition, the controller may be further configured to cause the micro-antenna array(s) to generate a steering beam focusing at multiple regions; compare the SPR information received by the micro-antenna array(s) from the plurality of regions; and determine anomalies in the terrain condition associated with one or more of the regions.
In various embodiments, the SPR system includes multiple micro-antenna arrays, each configured to focus at a different region. In addition, the controller may be further configured to based on the SPR information acquired by the first one of the micro-antenna arrays, map the terrain condition; based on the map, record and register the SPR information acquired by the second one of the micro-antenna arrays to the SPR information acquired by the first one of the micro-antenna arrays; and determine state information (e.g., a steering direction, an orientation, a velocity, a pose, an acceleration and/or a deceleration) associated with the vehicle.
Further, the micro-antenna array may be configured to receive multiple input signals or generate multiple output signals at one time so as to shape a beam generated therefrom or improve quality of the acquired real-time SPR information. The micro-antenna array may be configured in two-dimensional or three-dimensional. In some embodiments, the controller is further configured to combine or compare the acquired real-time SPR information over a time period so as to improve accuracy of the determined terrain condition and/or locational information associated with the vehicle.
In various embodiments, the micro-antenna elements are spaced apart from one another with a distance less than one-tenth of an average operating wavelength of the micro-antenna elements in air or on a substrate so as to improve a lateral and/or longitudinal resolution. In addition, the space between two of the micro-antenna elements may be determined based at least in part on a target location resolution and locations of the two micro-antenna elements in the micro-antenna array. In one embodiment, the micro-antenna elements have the same frequency range. Alternatively, all (or at least some) of the micro-antenna elements have different frequency ranges. In addition, the system may further include a single antenna element for acquiring real-time SPR information associated with the vehicle at a frequency range different from the frequency ranges of the micro-antenna elements.
In another aspect, the invention relates to a method of navigating a vehicle on a terrain. In various embodiments, the method includes providing an SPR system having one or more micro-antenna arrays, the micro-antenna array including multiple micro-antenna elements, each being configured to operate at a frequency range, the frequency ranges of the micro-antenna elements collectively spanning a full frequency range; activating the SPR system to acquire real-time SPR information associated with the vehicle; and based at least in part on the acquired real-time SPR information, determining information associated with the terrain and/or the vehicle. In one implementation, wherein the wide frequency range corresponds to frequencies between 10 kHz and 10 GHz. In addition, each micro-antenna element may have a peak operating frequency, and the peak operating frequencies associated with adjacent micro-antenna elements have a stepped-frequency difference.
As used herein, the terms “approximately” and “substantially” mean±10%, and in some embodiments, 5%. In addition, the terms “frequency band” and “frequency range” are used herein interchangeably. Reference throughout this specification to “one example,” “an example,” “one embodiment,” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the example is included in at least one example of the present technology. Thus, the occurrences of the phrases “in one example,” “in an example,” “one embodiment,” or “an embodiment” in various places throughout this specification are not necessarily all referring to the same example. Furthermore, the particular features, structures, routines, steps, or characteristics may be combined in any suitable manner in one or more examples of the technology. The headings provided herein are for convenience only and are not intended to limit or interpret the scope or meaning of the claimed technology.
In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, with an emphasis instead generally being placed upon illustrating the principles of the invention. In the following description, various embodiments of the present invention are described with reference to the following drawings, in which:
Refer first to
To mitigate the high-Q problem that degrades performance of NEMS ME antennas, the material and/or configuration (e.g., size or shape) associated with each micro-antenna element 102 herein may be selected to limit its bandwidth to a relatively narrow range (e.g., 2 kHz). In addition, adjacent micro-antenna elements 102 may have a stepped-frequency difference (e.g., 100 kHz) between the peak operating frequencies associated therewith, and the frequency bands (or frequency ranges) of the micro-antenna elements 102 in the micro-antenna array 100 may collectively span a wide spectral region (e.g., from 10 kHz to 10 GHz). For example, referring to
In some embodiments, each micro-antenna element 102 in the array 100 is independently controlled to transmit and/or receive signals in its associated frequency range. Alternatively, the micro-antenna elements 102 may be operated in a group manner such that the entire array 100 effectively acts as a single broadband transmitter and/or receiver. In one embodiment, the micro-antenna elements 102 in the array 100 are grouped into multiple series 104, 106; each series is independently controlled to transmit and/or receive signals within a collective frequency range associated with the micro-antenna elements 102 in the series. The frequency range Δf of different series may be substantially the same or different. In one embodiment, each series is a linear array and the spacing, d, between two series is approximately (or less than) one-tenth of the average wavelength associated with the elements 102 in air or on a substrate made of, for example, a dielectric material, a magnetic material, or an absorptive material so as to improve the lateral and/or longitudinal resolution.
In addition, the spacing between the two series 104, 106 of the micro-antenna elements 102 (or two micro-antenna elements 102) may be configured based on a target location resolution and the locations of the two series of micro-antenna elements (or two micro-antenna elements 102) in the micro-antenna array 100. In some embodiments, the series 104, 106 of micro-antenna elements 102 form a phased array and may receive multiple input signals and generate multiple output signals. Regardless of whether the micro-antenna elements 102 in the micro-antenna array 100 are operated in a grouped or individual manner, the signals transmitted and/or received by the micro-antenna elements 102 may be computationally combined to effectively cover the broadband spectral frequency range, Δf.
Referring to
In some embodiments, the SPR images are compared to SPR reference images that were previously acquired and stored for subsurface regions that at least partially overlap the subsurface regions for the defined route. The image comparison may be a registration process based on, for example, correlation; see, e.g., U.S. Pat. No. 8,786,485 and U.S. Patent Publication No. 2013/0050008, the entire disclosures of which are incorporated by reference herein. The route and/or location of the vehicle 204 and/or the terrain conditions of the route can be determined based on the comparison. In one embodiment, the route data is used to create a real-time map including the SPR information for navigating the vehicle 204. For example, based on the real-time SPR map information, the velocity, acceleration, orientation, angular velocity and/or angular acceleration of the vehicle 204 may be continuously controlled via a controller (further described below) so as to maintain travel of the vehicle 204 along a predefined route.
In some embodiments, the detected SPR signals are combined with other real-time information, such as the weather conditions, electro-optical (EO) imagery, vehicle health monitoring using one or more sensors employed in the vehicle 204, and any other suitable inputs, to estimate the terrain conditions of the route. The estimated terrain conditions may advantageously provide real-world terrain modeling as well as reduced computational expenses and/or complexity for modeling the terrain/vehicle interaction in real-time.
Referring to
Additionally or alternatively, the phases of the micro-antenna elements in one or more of the micro-antenna arrays 2061-n may be dynamically varied so as to focus in different directions/locations. For example, referring to
Additionally or alternatively, separate sets of micro-antenna arrays 206 may be distributed around the vehicle on which the SPR system 202 is implemented. For example, referring to
In one embodiment, the real-time SPR map information is transmitted from a controller 2121 associated with the front array 2061 to a controller 2122 associated with the rear array 2062 via communication modules 2141, 2142. The controllers 2101, 2102 may be implemented in hardware, software, or a combination of both, and may be different (e.g., identical) devices or integrated as a single device. Based on the received SPR map information, the rear controller 2122 may record and register the SPR signals obtained by the rear array 2062 to the signals received by the front array 2061 during transmission of the SPR map information. In one embodiment, the controller 2122 is configured to compare the data derived from signals obtained by the front array 2061 and rear array 2062 to determine state information, such as steering, orientation, velocity (speed and bearing), pose, acceleration and/or deceleration, during transmission of the SPR map information. Based thereon, a vehicle control module (further described below) may determine whether an action (e.g., a change of speed or bearing) is needed. That is, the front controller 2121 periodically transmits state information to the rear controller 2122, which then assesses the current state against previous states to make an independent control decision. Further details about registering the rear-array data to the front-array data are provided, for example, in U.S. patent application Ser. No. 16/933,395 (filed on Jul. 20, 2020), the entire contents of which are incorporated herein by reference.
Various embodiments described above relate to monitoring terrain conditions of the road in an outdoor surface environment. Alternatively, a vehicle may be controlled in an indoor environment, such as inside a building or within a complex of buildings. The vehicle can navigate hallways, warehouses, manufacturing areas and the like. In some embodiments, a vehicle may be controlled inside structures in regions that may be hazardous to humans, such as in a nuclear power facility, a hospital or a research facility where hazards may be present. Alternatively, the vehicle may be a mobile robot or other autonomous or controlled machinery capable of movement through a facility such as a factory or warehouse.
If the vehicle travels indoors, the SPR system 202 may be employed to obtain SPR images that include subsurface regions in and/or behind floors, ceilings or walls by attaching the SPR system 202 to, for example, the side or the top of the vehicle and orienting the SPR system in a preferred direction (which may be variable depending on the application, the vehicle's location, etc.). For example,
The SPR system 202 also includes a mobile SPR system (“Mobile System”) 306 having one or more SPR antenna arrays (e.g., micro-antenna arrays 100) as described above. The transmitting operation of the mobile SPR system 306 is controlled by one or more controllers (e.g., processors) 308 that also receive the return SPR signals detected by the SPR antenna arrays. The controller(s) 308 may generate SPR images of the subsurface region below the road surface and/or the road surface underneath the SPR antenna arrays.
The SPR image includes features representative of structure and objects within the subsurface region and/or on the road surface, such as rocks, roots, boulders, pipes, voids and soil layering, and other features indicative of variations in the soil or material properties in the subsurface/surface region. In various embodiments, a registration module 310 compares the SPR images provided by the controller(s) 308 to the SPR images retrieved from the SPR reference image source 304 to determine the terrain conditions of the road and/or locate the vehicle 204 (e.g., by determining the offset of the vehicle with respect to the closest point on the route). In addition, the registration module 310 may compare the SPR images acquired by different SPR antenna arrays affixed to the vehicle 204 to identify anomalies in the underlying terrain and/or the pose, velocity, and/or change in acceleration of the vehicle 204. In various embodiments, the locational information (e.g., offset data or positional error data) determined in the registration process is provided to a conversion module 312 that creates a navigation map for navigating the vehicle 204. For example, the conversion module 312 may generate GPS data corrected for the vehicle positional deviation from the route.
Alternatively, the conversion module 312 may retrieve an existing map from a map source 314 (e.g., other navigation systems, such as GPS, or a mapping service), and then localize the obtained locational information to the existing map. In one embodiment, the location map of the predefined route is stored in a database 216 in system memory and/or a storage device accessible to the controller 208. Additionally or alternatively, the location data for the vehicle 104 may be used in combination with the data provided by an existing map (e.g., a map provided by GOOGLE MAPS) and/or one or more other sensors or navigation systems, such as an inertial navigation system (INS), a GPS system, a sound navigation and ranging (SONAR) system, a LIDAR system, a camera, an inertial measurement unit (IMU) and an auxiliary radar system, one or more vehicular dead-reckoning sensors (based on, e.g., steering angle and wheel odometry), and/or suspension sensors to guide the vehicle 204. For example, the controller 308 may localize the obtained SPR information to an existing map generated using GPS. Approaches for utilizing the SPR system for vehicle navigation and localization are described in, for example, U.S. Pat. No. 8,949,024, the entire disclosure of which is hereby incorporated by reference.
In some embodiments, the SPR reference images also include terrain conditions associated therewith. Thus, by comparing the obtained SPR images to the SPR reference images, the terrain conditions associated with the SPR reference images acquired from the route may be determined. Again, the determined terrain conditions may then be provided to the conversion module 312 for creating a terrain map. The terrain map, in turn, may be combined with the navigation map described above. The terrain/navigation map may then be provided to a vehicle control module 316 coupled to the controller(s) 308 for autonomously operating the vehicle based thereon. For example, the vehicle control module 316 may include or cooperate with electrical, mechanical and pneumatic devices in the vehicle to control steering, orientation, velocity, pose and acceleration/deceleration of the vehicle. In some embodiments, the SPR system 202 includes an input database 318 that continuously feeds other real-time information (other than the SPR signals/SPR images), detected by other systems, to the conversion module 312 for updating and/or refining the terrain/navigation map.
It should be noted that the terrain condition and/or locational information associated with the vehicle described above are exemplary information that can be obtained from the SPR signals. One of ordinary skill in the art will understand that based on the acquired SPR signals and approaches described above, other information such as the terrain feature(s), locational information with the feature(s), state of the feature(s), material characteristics or properties associated with the feature(s), changes in feature(s) in the subsurface or on the surface, and/or the velocity, pose, orientation, acceleration and/or state of the vehicle, etc. can also be obtained and is thus within the scope of the present invention.
The controller(s) 212, 308 implemented in the vehicle may include one or more modules implemented in hardware, software, or a combination of both. For embodiments in which the functions are provided as one or more software programs, the programs may be written in any of a number of high level languages such as PYTHON, FORTRAN, PASCAL, JAVA, C, C++, C#, BASIC, various scripting languages, and/or HTML. Additionally, the software can be implemented in an assembly language directed to the microprocessor resident on a target computer; for example, the software may be implemented in Intel 80x86 assembly language if it is configured to run on an IBM PC or PC clone. The software may be embodied on an article of manufacture including, but not limited to, a floppy disk, a jump drive, a hard disk, an optical disk, a magnetic tape, a PROM, an EPROM, EEPROM, field-programmable gate array, or CD-ROM. Embodiments using hardware circuitry may be implemented using, for example, one or more FPGA, CPLD or ASIC processors.
In addition, the communication modules 2141, 2142 may include a conventional component (e.g., a network interface or transceiver) designed to provide wired and/or wireless communications therebetween. In one embodiment, the communication modules 2141, 2142 directly communicate with each other. Additionally or alternatively, the communication modules 2141, 2142 may indirectly communicate with each other via infrastructure, such as the public telecommunications infrastructure, a roadside unit, a remote platooning coordination system, a mobile communication server, etc. The wireless communication may be performed by means of a wireless communication system with WiFi, Bluetooth, infrared (IR) communication, a phone network, such as general packet radio service (GPRS), 3G, 4G, 5G, Enhanced Data GSM Environment (EDGE), or other non-RF communication systems such as an optical system, etc. In addition, the wireless communication may be performed using any suitable modulation schemes, such as AM, FM, FSK, PSK, ASK, QAM, etc.
The terms and expressions employed herein are used as terms and expressions of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described or portions thereof. In addition, having described certain embodiments of the invention, it will be apparent to those of ordinary skill in the art that other embodiments incorporating the concepts disclosed herein may be used without departing from the spirit and scope of the invention. Accordingly, the described embodiments are to be considered in all respects as only illustrative and not restrictive.
This application claims priority to and the benefit of, and incorporates herein by reference in its entirety, U.S. Provisional Patent Application No. 62/912,791, filed on Oct. 9, 2019.
| Number | Date | Country | |
|---|---|---|---|
| 62912791 | Oct 2019 | US |
