Patent Grant
11709251
Unmanned aerial systems (UASs) are being increasingly used for a variety of applications, including surveillance, communications, cargo transport, agriculture, law enforcement, and scientific research. Also known as unmanned aircraft systems, unmanned aerial vehicles (UAVs), and “drones”, UASs lack a human pilot, and therefore can be made much smaller than crewed aircraft. This small size reduces cost and power consumption, and eliminates on-board systems needed for human physiology and human safety. The lack of pilot and crew also makes UASs ideal platforms for high-endurance missions lasting several days, or longer.
Increasing use of UASs threatens airspace security in many ways. For example, more UASs leads to more accidents, such as collisions between UASs, collisions between UASs and other flying objects (e.g., airplanes, birds), and crashes. Debris from such accidents can injure nearby people and buildings. There is also concern about UASs being used to deliver dangerous payloads with malicious intent, either to civilian or military targets. Examples of such payloads include explosives, chemical or biological hazards, and radioactive materials. Other examples of malicious intent include wireless hijacking and control of UASs, electronic jamming, and spying.
The present embodiments feature mobile, monostatic radar nodes that cooperate to detect a UAS and determine its position in three spatial dimensions. Each radar node has full azimuthal coverage (i.e., 360°), and therefore can fully track the movement of the UAS regardless of how it moves and/or how each of the radar nodes move. The present embodiments can be used to monitor UASs as a proactive measure to prevent accidents or identify potential malicious intent. The present embodiments may also be used as part of a counter unmanned air system that uses the identified UAS position to jam, take control of, and/or damage the UAS. The present embodiments may also be used to locate and track other moving objects that are detectable by radar (e.g., ground vehicles, cars, trucks, boats, etc.) without departing from the scope hereof.
Each radar node has an antenna structure in which a plurality of panels is arranged as a right polygonal prism, where each panel includes a transmitting antenna array and a receiving antenna array. Each radar node uses one of its panels to measure the slant distance to the UAS using conventional radar techniques (e.g., monopulse, continuous-wave, pulsed Doppler, etc.). However, rather than measuring the azimuthal angle of the UAS, each radar node uses the geometry of the panels to place bounds on the azimuthal angle. For example, in one embodiment, the antenna structure of each radar node contains five panels arranged as a right pentagonal prism. When only one panel operates to detect the UAS, the radar node bounds the azimuthal location of the UAS to within a 720 azimuthal sector.
A first radar node transmits a first slant distance and first set of azimuthal bounds to a second radar node, which measures a second slant distance to the UAS position, and determines a second set of azimuthal bounds. By combining slant distances and azimuthal bounds with the locations of the nodes, the second radar node solves for the UAS position without any explicit measurement of the UAS's azimuthal position. Advantageously, this pair of radar nodes can obtain this one unique solution without a second ambiguous solution, as typically occurs in true-range trilateration in two Cartesian dimensions.
In embodiments, a radar node includes a plurality of antenna arrays arranged to transmit and receive radar beams with full azimuthal coverage. The radar node also includes an electronics module coupled to the plurality of antenna arrays. The electronics module includes a processor and a memory communicably coupled with the processor. The memory stores machine-readable instructions that, when executed by the processor, control the electronics module to receive a first radar position of an external radar node, a first elevation angle and a first slant range of an object measured by the external radar node, and a first azimuth field-of-view (FOV) of the external radar node within which the object was detected. The machine-readable instructions also control the electronics module to operate at least one of the plurality of antenna arrays to measure a second elevation angle and a second slant range of the object within a second azimuth FOV of said at least one of the plurality of antenna arrays. The machine-readable instructions also control the electronics module to identify, based on the first and second azimuth FOVs, an object half space within which the object is located. The half space is one of first and second half spaces separated by a vertical baseline plane that intersects the first radar position and a second radar position of the radar node. The machine-readable instructions also control the electronics module to calculate a position of the object within the object half space based on the first and second elevation angles, the first and second slant ranges, and the first and second radar positions. The machine-readable instructions also control the electronics module to output the position of the object.
In other embodiments, a surveillance method includes measuring, with a first radar node located at a first radar position and operating within a first azimuth FOV, a first elevation angle and a first slant range of an object. The method also includes measuring, with a second radar node located at a second radar position and operating within a second azimuth FOV, a second elevation angle and a second slant range of the object. The method also includes transmitting the first radar position, the first elevation angle, the first azimuth FOV, and the first slant range to the second radar node. The method also includes identifying, based on the first and second azimuth FOVs, an object half space within which the object is located, the half space being one of first and second half spaces separated by a vertical baseline plane that intersects the first and second radar positions. The method also includes calculating a position of the object within the object half space based on the first and second elevation angles, the first and second slant ranges, and the first and second radar positions.
The first and second radar nodes 100(1), 100(2) are mounted on respective first and second vehicles 102(1), 102(2) that are spatially separated by a baseline b, which may range from a few meters to tens of kilometers, or more. In
Denoting an object position of the UAS 130 by {right arrow over (u)}=(xU, yU, zU) and a first radar position of the first radar node 100(1) by {right arrow over (n)}1=(x1, y1, z1), the first slant range R1 can be expressed as R1=∥{right arrow over (u)}−{right arrow over (n)}1∥=((x1−xU)2+(y1−yU)2+(z1−zU)2)1/2, where {right arrow over (u)}−{right arrow over (n)}1 is a first relative position vector that represents the object position u relative to the first radar position {right arrow over (n)}1. Denoting a second radar position of the second radar node 100(2) by {right arrow over (n)}2=(x2, y2, z2), the second slant range R2 can be expressed as R2=∥{right arrow over (u)}−{right arrow over (n)}2∥=((x2−xU)2+(y2−yU)2+(z2−zU)2)1/2, where {right arrow over (u)}−{right arrow over (n)}2 is a second relative position vector that represents the object position {right arrow over (u)} relative to the second radar position {right arrow over (n)}2. As shown in
The first and second points 304(1), 304(2) are shown in
The first radar beam 110(1) may be a pencil-like beam that the first radar node 100(1) electronically steers between the azimuthal bounds ϕ1(a) and ϕ2(a). Alternatively, the first radar beam 110(1) may be a fan-shaped beam with an azimuthal beamwidth of Δϕ(a)=ϕ2(a)−ϕ1(a) and centered at (ϕ2(a)+ϕ1(a))/2. In either case, the first radar node 100(1) may also electronically steer the first radar beam 110(1) through a first elevation FOV to measure the first elevation angle θ1. The second radar beam 110(2) may be similarly shaped and electronically steered.
The second radar node 100(2) receives the reflection 112(2) from the UAS 130 to correlate the presence of the UAS 130 with a second azimuth FOV Φ(b)=[ϕ1(b), ϕ2(b)] within which the second radar node 100(2) transmitted the second radar beam 110(2). Azimuthal angles ϕ(b) for the second radar node 100(2) may be defined relative to a second local azimuthal reference direction, which is taken to be the second direction {right arrow over (d)}2 in the example of
To identify on which side of the extended baseline b* the UAS 130 is located, the first radar node 100(1) determines a baseline vector {right arrow over (b)} between the first radar position {right arrow over (n)}1=(x1, y1, z1) and the second radar position {right arrow over (n)}2=(x2,y2, z2). The magnitude of the baseline vector {right arrow over (b)} is shown in
The first radar node 100(1) determines the first and second azimuth FOVs Φ(a), Φ(b) relative to the baseline vector {right arrow over (b)}. In the example of
In
In some embodiments, the first radar node 100(1) identifies the object half space after calculating both the first and second points 304(1), 304(2). The first radar node 100(1) then identifies which one of the first and second points 304(1), 304(2) lies within the object half space, and returns the identified point 304 as the correct ground-track solution. The point 304 corresponding to the ambiguous solution may be discarded. In other embodiments, the first radar node 100(1) first identifies the object half space, and then directly calculates only the one of the first and second points 304(1), 304(2) that is the correct ground-track solution. In this case, the ambiguous solution does not need to be calculated and discarded. In either case, the first radar node 100(1) may combine the correct ground-track solution (i.e., the coordinates xU and yU of the UAS 130) with the coordinate zU of the UAS 130 to obtain the object position {right arrow over (u)}=(xU, yU, zU) of the UAS 130 in all three spatial dimensions. The first radar node 100(1) may wirelessly transmit the object position {right arrow over (u)} back to the second radar node 100(2).
One or both of the first radar node 100(1) and the first vehicle 102(1) may be equipped with a direction sensor (e.g., see direction sensor 816 in
The first radar node 100(1) uses the first direction {right arrow over (d)}1 and baseline vector {right arrow over (b)} to determine a first azimuthal offset φ(a). The first radar node 100(1) subtracts the first azimuthal offset φ(a) from the azimuthal bound ϕ1(a) to obtain a first baseline-reference azimuthal bound δ1(a)=ϕ1(a)−φ(a). Although not shown in
One or both of the second radar node 100(2) and second vehicle 102(2) may be similarly equipped with a direction sensor that measures the second direction {right arrow over (d)}2 as a bearing (or azimuth) relative to the global reference direction. The second radar node 100(2) may then wirelessly transmit the second direction {right arrow over (d)}2 to the first radar node 100(1), which uses the second direction {right arrow over (d)}2 and baseline vector {right arrow over (b)} to determine a second azimuthal offset φ(b). The first radar node 100(1) subtracts the second azimuthal offset φ(b) from the azimuthal bounds ϕ1(b) and ϕ2(b) to obtain third and fourth baseline-reference azimuthal bounds δ1(b)=ϕ1(b)−φ(b) and δ2(b)=ϕ2(b)−φ(b), respectively. If δ1(b) and δ2(b) are both positive, then the second azimuth FOV Φ(b) opens entirely toward the half space I. If δ1(b) and δ2(b) are both negative, then the first azimuth FOV Φ(b) opens entirely toward the half space II.
In
Each rectangular panel 612 has one transmitting antenna array 602 and one receiving antenna array 604. Each antenna array 602, 604 has a plurality of antenna elements 610. In the example of
By arranging the rectangular panels 612 as a right polygonal prism, the antenna structure 600 can advantageously transmit and receive radar beams (e.g., the radar beams 110 in
When one of the rectangular panels 612(i) transmits a radar beam within its corresponding azimuthal sector 702(i), and receives a corresponding reflection indicating the presence of the UAS 130, the radar node 100 uses the sector bounds σi-1 and σi as the azimuthal bounds ϕ1 and ϕ2. The radar node 100 may then process the azimuthal bounds ϕ1 and ϕ2, as described above, to determine if the azimuthal sector 702(i) opens into the half space I or the half space II. Alternatively, the radar node 100 may wirelessly transmit the sector bounds σi-1 and σi to another radar node 100 that determines, based on the sector bounds σi-1 and σi, if the azimuthal sector 702(i) opens into the half space I or the half space II.
In
Each of the radar nodes 100(1), 100(2) uses the geometry of the rectangular panels 612 to bound the azimuth FOV (i.e., set upper and lower limits on the azimuthal angle) of the UAS 130, and therefore does not need to explicitly measure an azimuthal angle of the UAS 130 (or a azimuth FOV subtended by the UAS 130). However, one or both of the radar nodes 100(1), 100(2) may be configured to explicitly measure an azimuthal angle of the UAS 130. For example, each radar node 100 may be implemented as a monopulse radar system that transmits a monopulse radar beam with an azimuthal angular beamwidth that is less than the azimuthal span Δσ. Using one transmitting antenna array 602(i), the radar node 100 may electronically steer the monopulse radar beam within the corresponding sector bounds σi-1 and σi, thereby transmitting radiation at all azimuthal angles of the sector 702(i). The radar node 100 may then process the reflection received by the corresponding receiving antenna array 604(i) to measure a center azimuthal angle of the UAS 130 (e.g., via sum and difference patterns). The center azimuthal angle may then be processed similarly to the azimuthal bounds ϕ1(a) and ϕ2(a) (e.g., transformed into a baseline-referenced azimuthal angle) to determine which of the half spaces I and II is the object half space (e.g., based on the sign of the baseline-referenced azimuthal angle).
Alternatively, the radar node 100 may process the reflection to measure an azimuth FOV subtended by the UAS 130. For example, this FOV may be determined by an uncertainty in the measured center azimuthal angle (which is typically less than the azimuthal angular beamwidth of the transmitted monopulse radar beam). Given sufficient signal-to-noise ratio of the detected reflection, the measured azimuth FOV may be smaller than the azimuthal span Δσ that is set by the geometry of the rectangular panels 612. When this occurs, the smaller azimuth FOV provides tighter bounds on the object location of the UAS 130 that may then be processed similarly to the azimuthal boundaries ϕ1(a) and ϕ2(a) to determine which of the half spaces I and II is the object half space. One advantage of using monopulse radar techniques with the antenna structure 600 is that the tighter bounds can be used to identify the object half space with greater certainty.
In certain embodiments, the radar node 100 implements monopulse radar techniques to measure an elevation angle θ of the UAS 130 (e.g., see elevation angles θ1 and θ2 in
In some of these embodiments, the radar node 100 implements monopulse radar only to measure the elevation angle θ. In these embodiments, the transmitted radar beam may be shaped as a fan beam that fills the azimuthal span Δσ without the need to electronically steer the radar beam in azimuth. In other embodiments, the radar node 100 implements monopulse radar to measure both azimuthal and elevation angles of the UAS 130. In these embodiments, the transmitted radar beam may be shaped as a pencil beam that is scanned in both azimuth and elevation. More generally, the radar node 100 may measure the azimuth and elevation angles of the UAS 130 using any combination of monopulse radar, conical scanning, and lobe switching. The radar node 100 may measure one or both of the azimuth and elevation angles using another technique without departing from the scope hereof.
In some embodiments, each radar node 100 either additionally or alternatively measures a speed or velocity of the UAS 130. For example, each radar node 100 may implement frequency-modulated continuous wave (FMCW) radar to measure, via the Doppler effect, a velocity of the UAS 130 along the radial direction. In this case, the first and second radar nodes 100(1), 100(2) can cooperate to identify both components of a ground-track velocity vector of the UAS 130. For example, the first radar node 100(1) measures a first velocity of the UAS 130, and the second radar node 100(2) measures a second velocity of the UAS 130. The second radar node 100(2) wirelessly transmits the second velocity to the first radar node 100(1), which determines movement of the UAS 130 based on the first and second velocities. The first and second radar nodes 100(1), 100(2) may also receive respectively first and second vehicular velocities of the first and second vehicles 102(1), 102(2). The second radar node 100(2) may wirelessly transmit the second vehicular velocity to the first radar node 100(1), which then additionally uses the first and second vehicular velocities to determine the movement of the UAS 130 (e.g., ground speed).
Each radar node 100 may implement another type of Doppler radar (e.g., continuous-wave, pulsed Doppler, coherent pulsed Doppler, etc.) without departing from the scope hereof. It should be appreciated that velocity measurements can be implemented independent of angular measurements. Therefore, in some embodiments the radar node 100 implements both FMCW radar (or another type of Doppler radar) and monopulse radar (or another type of angular measurement). In other embodiments, the radar node 100 implements only one of FMCW radar and monopulse radar. In yet other embodiments, the radar node 100 implement neither speed/velocity measurements nor explicit azimuthal measurements.
When two or more radar nodes 100 operate simultaneously, a first radar node 100 may detect a reflection of a radar beam transmitted by a second radar node 100 (i.e., bistatic radar). To ensure that each radar node 100 can identify the reflection of its own transmitted radar beam, the radar nodes 100 may be configured to operate in one of several frequency bands. In this case, several radar nodes 100 can communicate with other to prevent more than one radar node 100 from using the same band. Alternatively, multiple radar nodes 100 can cooperate to use time-division multiplexing in which each radar node 100 is assigned a unique time slot within which it transmits and receives (and no other radar node 100 transmits and receives). Alternatively, the radar nodes 100 can use orthogonal coding on the transmitted radar beams.
The ROM 806 stores machine-readable instructions (shown as firmware 860 in
The RAM 808 stores data 840 used by the processor 804 when executing the firmware 860. In
The object detector 864, when executed by the processor 804, controls the radar control and acquisition module 814 to (i) drive the antenna structure 600 to transmit the first radar beam 110(1), and (ii) process the first reflection 112(1) received by the antenna structure 600 to measure the first slant range R1 and first elevation angle θ1 of the UAS 130, and to determine the sector i (where 1≤i≤n) within which the UAS 130 is detected. The radar control and acquisition module 814 implements all radar functionality for the first radar node 100(1), including beamsteering, timing, waveform generation, digitization, monopulse beam generation and signal processing (when monopulse radar is implemented), FMCW signal generation and processing (when FMCW is implemented), and so on. The radar control and acquisition module 814 transmits R1, θ1, and i over the system bus 802 to the RAM 808, where the first slant range R1 and elevation angle θ1 are stored in the first node data 842. The object detector 864 further controls the radar-tracking module 800 to look up the two sector boundaries σi-1 and σi for the sector i, and store these two sector boundaries as the azimuthal boundaries ϕ1(a) and ϕ2(a) of the first node data 842. The object detector 864 may also control the radar-tracking module 800 to calculate, and store in the first node data 842, the first horizontal range r1 and height h.
The self-position communicator 866, when executed by the processor 804, controls the radar-tracking module 800 to obtain the first radar position {right arrow over (n)}1=(x1, y1, z1) from the positioning unit 818. The I/O block 822 receives {right arrow over (n)}1 from the positioning unit 818 (e.g., in response to a query sent to the positioning unit 818), and transmits {right arrow over (n)}1 over the system bus 802 to the RAM 808 for storage in the first node data 842. The positioning unit 818 may be a GPS receiver or similar receiver that implements satellite-based positioning. The positioning unit 818 may also include an inertial measurement unit that uses dead-reckoning to track {right arrow over (n)}1 between periodic updates from the GPS receiver (or when GPS signals are unavailable).
The self-direction communicator 868, when executed by the processor 804, controls the radar-tracking module 800 to receive the first direction {right arrow over (d)}1 from the direction sensor 816. The I/O block 824 receives {right arrow over (d)}1 from the direction sensor 816 (e.g., in response to a query sent to the direction sensor 816), and transmits {right arrow over (d)}1 over the system bus 802 to the RAM 808 for storage in the first node data 842. In some embodiments, the direction sensor 816 is a magnetic compass or gyrocompass. In some embodiments, the positioning unit 818 combines an inertial measurement unit with a GPS receiver connected to two spatially separated GPS antennas. In these embodiments, the positioning unit 818 determines both the first radar position {right arrow over (n)}1 and first direction {right arrow over (d)}1 without the need for a separate direction sensor 816. In some embodiments, the radar-tracking module 800 or positioning unit 818 determines {right arrow over (d)}1 from a temporal sequence of first radar positions recorded by the positioning unit 818, e.g., by extrapolating the temporal sequence in space.
The side-channel communicator 870, when executed by the processor 804, controls the side-channel transceiver 810 to wirelessly communicate with the second radar node 100(2). In some embodiments, the side-channel transceiver 810 receives data obtained by the second radar node 100(2), including the second radar position {right arrow over (n)}2=(x2, y2, z2) and second direction {right arrow over (d)}2 of the second radar node 100(2), azimuthal boundaries ϕ1(b) and ϕ2(b), and the measured second slant range R2 and second elevation angle θ2. The side-channel transceiver 810 transmits this received data over the system bus 802 to the RAM 808 for storage in the second node data 844. In some embodiments, the radar-tracking module 800 transmits to the second radar node 100(2), via the side-channel transceiver 810, one or more of the first radar position {right arrow over (n)}1=(x2,y2, z2), first direction {right arrow over (v)}1, azimuthal boundaries ϕ1(a) and ϕ2(a), slant range R1, and elevation angle θ1 obtained by the first radar node 100(1).
The half-space determiner 862, when executed by the processor 804, controls the radar-tracking module 800 to (i) calculate the baseline vector {right arrow over (b)}, (ii) determine the azimuthal offsets φ(a) and φ(b), (iii) calculate the baseline-reference azimuthal boundaries δ1(a), δ2(a), δ1(b), and δ2(b), and (iv) identify which of the half spaces I/II is the object half space 846.
The ground-track solver 872, when executed by the processor 804, controls the radar-tracking module 800 to calculate the correct ground-track solution 850 based on the first node data 842, the second node data 844, and the determined object half space 846. The ground-track solver 872 also controls the radar-tracking module 800 to determine the object position {right arrow over (u)}=(xU, yU, zU) from the ground-track solution 850. In some embodiments, the ground-track solver 872 controls the radar-tracking module 800 to first calculate both candidate ground-track solutions, and then use the object half space 846 to identify which of the candidate ground-track solutions is the correct ground-track solution 850.
The radar-tracking module 800 may also include an I/O block 820 for reporting the object position {right arrow over (u)}=(xU, yU, zU) to a peripheral device (not shown). The peripheral device may be a display that plots the object position {right arrow over (u)} on a map. Alternatively, the I/O block 820 may be a network adapter for communicating the object position {right arrow over (u)} to an external computing device. Alternatively or additionally, the radar-tracking module 800 may wirelessly transmit the object position {right arrow over (u)} to the second radar node 100(2) via the side-channel transceiver 810. Alternatively or additionally, the radar-tracking module 800 may transmit the object position {right arrow over (u)} to the radar control and acquisition module 814 to maintain tracking of the UAS 130.
The processor 804 may be any type of circuit capable of performing logic, control, and input/output operations. For example, the processor 804 may include one or more of a microprocessor with one or more central processing unit (CPU) cores, a graphics processing unit (GPU), a digital signal processor (DSP), a field-programmable gate array (FPGA), a system-on-chip (SoC), and a microcontroller unit (MCU). The processor 804 may also include a memory controller, bus controller, one or more co-processors, and/or other components that manage data flow between the processor 804 and other circuits communicably coupled to the system bus 802. The processor 804 may be implemented as a single integrated circuit (IC), or as a plurality of ICs. In some embodiments, one or more of the processor 804, ROM 806, and RAM 808 are implemented as a single IC. The processor 804 may use a complex instruction set computing (CISC) architecture, or a reduced instruction set computing (RISC) architecture.
Each of the I/O blocks 820, 822, and 824 may implement a communication protocol for sending data to, and receiving data from, a peripheral device. For example, each of the I/O blocks 820, 822, and 824 may be a serial communication interface (e.g., RS-232, RS-422, RS-485, etc.), a parallel communication interface (e.g., GPIB, PCI, SCSI, etc.), a synchronous serial communication interface (e.g., I2C, SPI, SSC, etc.), a universal serial bus (USB) interface, a multi-media card interface (e.g., SD card, Compact Flash, etc.), a wired network interface (e.g., Ethernet, Infiniband, Fibre Channel, etc.), a wireless network interface (e.g., WiFi, Bluetooth, BLE, ZigBee, ANT, etc.), a cellular network interface (e.g., 3G, 4G, 5G, LTE), an optical network interface (e.g., SONET, SDH, IrDA, etc.), and a fieldbus interface. The radar-tracking module 800 may include additional I/O functionality, as needed, for communicating with additional peripherals. For example, the radar-tracking module 800 may include one or more additional network interfaces (e.g., an Ethernet port or WiFi adapter) used to program the firmware 860.
While
Any of the above system and method embodiments may be alternatively configured to locate and track only horizontal motion of an external object. In this case, the height h may be assumed to zero, and the object position {right arrow over (u)}=(xU,yU) has only two spatial coordinates (i.e., the third spatial coordinate zU is ignored). Such embodiments may be used to track vehicles that move only, or primarily, horizontally. Examples includes watercraft and ground-based vehicles.
Any of the above system and method embodiments may be alternatively configured with the first and second radar nodes 100(1), 100(2) being stationary. In this case, the positions {right arrow over (n)}1 and {right arrow over (n)}2 of the first and second radar nodes 100(1), 100(2) are fixed, which in turn fixes the baseline b and azimuthal reference directions. As a result, the second radar node 100(2) does not need to continually transmit its position and azimuthal reference direction to the first radar node 100(1). Furthermore, it is easier to implement wired communication between the first and second radar nodes 100 (e.g., Ethernet cable or fiber-optic cable) when the radar nodes 100(1), 100(2) have fixed positions. Thus, the terms “transmit” and “receive” maybe used herein to include wired communication, in addition to or instead of, wireless communication.
In the block 904, a second radar node measures a second elevation angle and a second slant range. The second radar node is located at a second radar position and operates within a second azimuth FOV. In one example of the block 904, the second radar node 100(2) of
In the block 906, the first radar position, first elevation angle, first azimuth FOV, and first slant range are transmitted to the second radar node. In one example of the block 906, the second radar node 100(2) of
In the block 908, an object half space, within which the object is located, is identified based on the first and second half spaces. The object half space is one of first and second half spaces separated by a vertical baseline plane that intersects the first and second radar positions. In one example of the block 908, the first radar node 100(1) identifies (e.g., using the radar-tracking module 800) in which of the half spaces I and II the UAS 130 is located. As shown in
In the block 910, a position of the object within the object half space is calculated based on the first and second elevation angles, the first and second slant ranges, and the first and second radar positions. In one example of the block 910, the first radar node 100(1) calculates (e.g., using the radar-tracking module 800 of
Although not shown in
In one embodiment of the method 900, the first radar node 100(1) wirelessly transmits the first radar position, first elevation angle, first azimuth FOV, and first slant range, to a radar processing station that receives and processes radar data. Similarly, the second radar node 100(1) wirelessly transmits the second radar position, second elevation angle, second azimuth FOV, and second slant range to the radar processing station. The radar processing station is external to the first and second radar nodes 100(1), 100(2), and need not be a radar system. The radar processing station processes the received data to identify the object half space and calculate the position of the object (i.e., the radar processing station performs the blocks 908 and 910 of the method 900). The radar processing station may then output the position of the object. For example, the radar processing station may wireless transmit the position to one or both of the first and second radar nodes 100(1), 100(2). Alternatively, the radar processing station may transmit the position of the object to another piece of equipment.
In the block 1008, a plurality of candidate positions is calculated based on the first and second elevation angles, the first and second slant ranges, and the first and second radar positions. In one example of the block 1008, the first radar node 100(1) calculates (e.g., using the radar-tracking module 800 of
In the block 1010, a position of the object is identified from the plurality of candidate positions based on the first and second azimuth FOVs. In one example of the block 1010, the first radar node 100(1) identifies which of the half spaces I and II is the object half space, and then selects, as the object position {right arrow over (u)}, the one of the points 304(1), 304(2) located within the object half space. The first radar node 100(1) may discard the other of the points 304(1), 304(2).
In one embodiment of the method 1000, the first radar node 100(1) wirelessly transmits the first radar position, first elevation angle, first azimuth FOV, and first slant range, to the radar processing station described previously. Similarly, the second radar node 100(1) wirelessly transmits the second radar position, second elevation angle, second azimuth FOV, and second slant range to the radar processing station. The radar processing station processes the received data to calculate the plurality of candidate positions identify the position of the object from the candidate positions (i.e., the radar processing station performs the blocks 1008 and 1010 of the method 1000). The radar processing station may then output the position of the object. For example, the radar processing station may wireless transmit the position to one or both of the first and second radar nodes 100(1), 100(2). Alternatively, the radar processing station may transmit the position of the object to another piece of equipment.
Additional Antenna Geometries
When the UAS 130 is located above the first and second radar nodes 100(1), 100(2) (e.g., when the height h in
In
Similar to the antenna structure 1100 of
Changes may be made in the above methods and systems without departing from the scope hereof. It should thus be noted that the matter contained in the above description or shown in the accompanying drawings should be interpreted as illustrative and not in a limiting sense. The following claims are intended to cover all generic and specific features described herein, as well as all statements of the scope of the present method and system, which, as a matter of language, might be said to fall therebetween.
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| 20140028494 | Ksienski | Jan 2014 | A1 |
| 20150000003 | Blakely | Jan 2015 | A1 |
| 20150355324 | Minear | Dec 2015 | A1 |
| 20170000010 | Raetzman | Jan 2017 | A1 |
| 20180088221 | Yomo | Mar 2018 | A1 |
| 20190204435 | Poiger | Jul 2019 | A1 |
| 20200158862 | Mahmoud | May 2020 | A1 |
| 20200370920 | Ahmed | Nov 2020 | A1 |
| 20220066012 | Jansen | Mar 2022 | A1 |
| 20220066015 | Burghardt | Mar 2022 | A1 |
| 20220146623 | Lao | May 2022 | A1 |
| 20220350010 | Sagi | Nov 2022 | A1 |
