Transferring infrastructure information to a vehicle via ground penetrating radar

Abstract

Methods and apparatus are disclosed for communicating infrastructure information to a vehicle via ground penetrating radar. A vehicle includes an antenna positioned to broadcast radio waves downward of the vehicle, a ground penetrating radar system, and an active safety module. The ground penetrating radar system determines types of reflectors and spatial relationships between the reflectors from radar cross sections detected by the antenna, and generates a signal from the shapes and spatial relationships. The active safety module determines environmental data from the signal, and autonomously controls the vehicle from the environmental data.

Description

TECHNICAL FIELD

[0001] The present invention relates generally to autonomous vehicles, and more particularly, to communicating infrastructure information to a vehicle via ground penetrating radar. BACKGROUND

[0002] Autonomous and semi-autonomous vehicles handle the powered functions of the vehicle without direct driver input. Autonomous vehicles substantially control all powered functions, while semi-autonomous vehicles handle some powered functions (sometimes referred to as "driver assist") (e.g., lane keep assist, automatic driving, remote parking assist, etc.). Traditionally, these vehicles include sensors (e.g., standard radar (RADAR), laser radar (LiDAR), video cameras, ultrasonic sensors, etc.) that provide information about the environment in which the vehicle is traveling, communication modules (e.g., cellular modems, vehicle-to-vehicle modules, etc.), and location data (e.g., received via global positioning system (GPS) receivers, etc.). Video cameras, for example, have limitations that can affect lane tracking due to low light conditions, deteriorated road markings, and environmental conditions (e.g., snow, etc.) that can obscure road markings. As another example, in urban canyons, GPS signals can be unreliable to provide a sufficiently accurate location of the vehicle to determine which lane of a multi-lane road the vehicle is in. SUMMARY

[0003] The appended claims define the application. The summary of the invention summarizes aspects of the embodiments and should not be used to define the claims. The technology described according to the present invention is contemplated to have other embodiments that are apparent to those skilled in the art in view of the following detailed description and Figures and that are intended to fall within the scope of the present invention.

[0004] Example embodiments are disclosed for communicating infrastructure information to a vehicle via ground penetrating radar. A vehicle includes an antenna positioned to broadcast radio waves below the vehicle, a ground penetrating radar system, and an active safety module. The ground penetrating radar system determines shapes of reflectors and spatial relationships between the reflectors from radar cross sections detected by the antenna, and generates a signal from the shapes and the spatial relationships. The active safety module determines environmental data from the signal, and autonomously controls the vehicle from the environmental data.

[0005] An example method includes broadcasting radio waves below a vehicle with a ground penetrating radar antenna fixed to the vehicle. The method also includes determining types of reflectors and spatial relationships between the reflectors from radar cross sections detected by the antenna. In addition, the method includes generating a signal from the shapes and the spatial relationships and determining environmental data from the signal. The method also includes autonomously controlling the vehicle from the environmental data. BRIEF DESCRIPTION OF DRAWINGS

[0006] For a better understanding of the present application, reference can be made to the embodiments illustrated in the following drawings. The components in the drawings are not necessarily to scale, and the relative dimensions of related elements can be exaggerated, in some instances, for the sake of emphasis and clarity. Furthermore, the system components can be variously arranged as is known in the art. Also, in the drawings, like reference numerals designate corresponding parts throughout the several views.

[0007] Figure 1 A vehicle operating according to the teachings of the present application is shown;

[0008] Figure 2 An exemplary radar cross section showing different shaped reflectors embedded under the surface of a roadway is shown;

[0009] Figure 3 A three-dimensional placement of reflectors embedded under the surface of a roadway is shown;

[0010] Figure 4 An exemplary roadway with reflectors embedded under the surface of a roadway is shown;

[0011] Figure 5 is a block diagram of the electronic components of the vehicle; Figure 1

[0012] Figure 6 is a flowchart of a method of transmitting infrastructure information to a vehicle that can be implemented by the electronic components of Figure 5 Figure 1 The specific embodiments of the present application will now be described with reference to the drawings. Identical reference numerals in different figures designate the same, similar, or equivalent parts.DETAILED DESCRIPTION

[0013] While the application can be susceptible to embodiment in various forms, there are described in the following description and shown in the drawings some specific embodiments of the application. The specific embodiments of the application as described and illustrated are not intended to limit the application to the specific embodiments described or illustrated. The specific embodiments of this application are presented by way of example only and in no way limit the scope of the application.

[0014] Autonomous and semi-autonomous vehicles use information about the environment to navigate through the roads in that environment autonomously. This information includes the location and direction of lanes, speed limits, warnings (e.g., school zones, mid-block crosswalks, hospitals, sharp curves, steep slopes, etc.), and / or traffic controls (e.g., traffic signals, stop signs, yield signs, etc.). Typically, vision-based systems or perception-based systems (e.g., cameras, LiDAR, forward-facing RADAR, etc.) have difficulty distinguishing environmental features, especially when road conditions (e.g., lane markings, crosswalks, stop lines, etc.) and / or informational signs (e.g., traffic signals, stop signs, yield signs, etc.) are obscured (e.g., due to weather, wear, etc.). Additionally, GPS signals on the commercial band cannot provide sufficient accuracy to determine which lane of a multi-lane road a vehicle is traveling on.​​

[0015] Increasingly, vehicles are manufactured to include vehicle radar systems that include radar transceivers that typically operate at a frequency of 77 gigahertz (GHz) due to radio frequency propagation characteristics and resolution. These radar transceivers are embedded in front and rear bumpers and / or sides of the vehicle. As described below, the vehicle additionally or alternatively includes one or more ground penetrating radar (GPR) antennas located at the bottom of the vehicle such that signals produced by the GPR antennas propagate through the road surface beneath the vehicle. The GPR antennas operate at a relatively low frequency (e.g., 10 megahertz (MHz) to 2.6 GHz) to facilitate ground penetration. In some examples, when the operating frequency of the GPR antennas is very low (e.g., 10 MHz to 100 MHz, etc.), post-processing techniques are applied (e.g., via Laplacian filtering, inverse sharpening masks, bilateral filtering, etc.) to improve resolution of the response. The GPR antennas emit radio frequency energy and then read reflections from reflectors to determine characteristics of the three-dimensional space beneath the vehicle.

[0016] As described below, reflectors are embedded beneath the surface of the roadway. Using the GPR antennas, the vehicle determines characteristics of the reflectors embedded beneath the surface of the roadway beneath the vehicle. The reflectors have different geometrical shapes that produce different radar cross sections when radio waves reflect from the reflectors. Additionally, two or more reflectors are positioned beneath the surface in a predefined three-dimensional pattern. The reflectors have specific reflection cross sections (sometimes referred to as “patterns” or “signatures”) that are robust to deviations in the angle of incidence. In this way, changes due to installation and movement over time do not substantially change the three-dimensional relationship of the reflectors. The active safety module of the vehicle detects the different depths and different radar cross sections that form the predefined three-dimensional pattern. The detected pattern is compared to a list of known patterns to determine information conveyed by the pattern embedded beneath the surface of the roadway. The information that can be conveyed includes a direction of travel identifier (e.g., northbound, southbound, etc.), a lane identifier (e.g., right lane, left lane, center lane, turn lane, entrance ramp, exit ramp, etc.), road information (e.g., road curvature, road grade, etc.), speed limit information, traffic control information (e.g., stop sign, traffic signal, yield sign, stop line, mid-block crosswalk, etc.), and / or warning information (e.g., school zone, hospital zone, etc.), etc. This information is forwarded to autonomous functions of the vehicle to supplement information from other sources (e.g., vehicle radar, lidar, ultrasonic sensors, GPS receivers, etc.).

[0017] Figure 1A vehicle 100 operating in accordance with the teachings of the present disclosure is shown. The vehicle 100 of the illustrated example uses a ground penetrating radar (GPR) system 102 to detect a pattern of reflectors 104 to determine environmental data about a roadway 106 on which the vehicle 100 is traveling. The vehicle 100 can be a standard gasoline-powered vehicle, a hybrid vehicle, an electric vehicle, a fuel cell vehicle, and / or any other vehicle type of mobile tool. The vehicle 100 includes mobility-related components such as a powertrain system having an engine, electric motor, transmission, suspension, drive shaft, and / or wheels, etc. The vehicle 100 can be semi-autonomous (e.g., control some routine power functions by the vehicle 100) or autonomous (e.g., control power functions by the vehicle 100 without driver input). In the illustrated example, the vehicle 100 includes an autonomy unit 108, the GPR system 102, and an active safety module 110.

[0018] The autonomy unit 108 communicates with electronic control units (ECUs) that control power functions of the vehicle 100 (e.g., steering, braking, and throttle, etc.). The autonomy unit 108 includes hardware and firmware to facilitate autonomously navigating the vehicle 100 in various traffic scenarios using cameras, range detection systems (e.g., vehicle radar, LiDAR, ultrasonic sensors, etc.), and / or navigation data / vehicle position data (e.g., coordinates from a global positioning system (GPS) receiver, horizon data, vehicle state data from an inertial measurement unit (IMU), etc.) without driver intervention. Additionally, in the illustrated example, the autonomy unit uses environmental data from the active safety module 110 (e.g., travel direction identifiers, lane identifiers, road information, speed limit information, traffic control information, and / or warning information, etc.).

[0019] The GPR system 102 is positioned at the bottom of the vehicle 100 to direct radio frequency (RF) waves 112 toward the roadway 106 underneath the vehicle 100. In the illustrated example, the vehicle 100 includes a radar antenna or radar antenna array 114. Alternatively, in some examples, the GPR system 102 includes multiple radar antennas or radar antenna arrays 114 positioned at the bottom of the vehicle 100. The operating frequency of the GPR system 102 is a low frequency (e.g., 10 MHz to 2.6 GHz) that facilitates ground penetration. The GPR system 102 detects features of the roadway 106 underneath the vehicle 100.

[0020] In the illustrated example, the road 106 includes a surface layer 116 (e.g., made of asphalt, concrete, etc.), a base layer 118 (e.g., made of crushed stone, slag, concrete, or slate, etc.), and an underground layer 120 (e.g., composed of dirt, etc.) below. The reflectors 104 are embedded in the underground layer 120. In some examples, the reflectors have a spatial relationship defined at least in part by some of the set of reflectors embedded in the underground layer at different depths. The reflectors 104 have different possible geometries (e.g., flat plates, spheres, tetrahedrons, corner castings, etc.) that have different radar cross-sections when detected by the GPR system 102. Figure 2 Different radar cross-sections 202, 204, and 206 are illustrated. For example, one radar cross-section 202 is an example of a reflector 104 that is shaped like a flat plate. Another radar cross-section 204 is a spherical reflector 104. Another radar cross-section 206 is a tetrahedral reflector 104. Returning to Figure 1 , the reflectors 104 are positioned within the underground layer 120 in a predefined three-dimensional pattern. In some examples, the three-dimensional pattern includes reflectors 104 with different shapes that produce different radar cross-sections (e.g., the radar cross-sections 202, 204, and 206). Figure 2

[0021] Figure 3 A plurality of reflectors 104 with a predefined spatial relationship are illustrated. The spatial relationship can have components in the x-axis, y-axis, and / or z-axis. For example, some patterns can include only spatial relationships in the x-axis, y-axis, or z-axis, or the spatial relationship can have components in any of the three axes. The GPR system 102 uniquely identifies the cross-sections of the reflectors 104 and the predefined spatial relationship. The GPR system 102 generates signals based on the cross-sections of the reflectors 104 and the predefined spatial relationship. As the vehicle 100 traverses the road, the GPR system 102 detects the pattern of reflectors 104, and the GPR system 102 produces a series of signals.

[0022] ​The active safety module 110 controls functions of the vehicle 100 that assist the vehicle 100 and / or the driver to safely traverse the roadway 106. These functions include anti-lock braking systems, electronic stability control, traction control, brake assist, adaptive cruise control, and / or collision avoidance, among others. In some examples, in an autonomous vehicle, the active safety module 110 can be combined with the autonomous unit 108. Additionally, in some examples, a semi-autonomous vehicle can be the active safety module 110 alone. The active safety module 110 receives signals from the GPR system 102 and determines environmental data corresponding to the signals and forwards the environmental data to the autonomous unit 108. The active safety module 110 includes a database and / or lookup table that associates signals with environmental data. For example, a particular signal can correspond to a speed limit of 25 miles per hour (mph). In some examples, the active safety module 110 is communicatively coupled to an external network (e.g., via a cellular modem, etc.) to connect to a server that (a) stores the database and / or lookup table and / or (b) provides associations to the database and / or lookup table for a geographic region in which the vehicle 100 is located.

[0023] Figure 4 An example roadway is shown in which reflectors 104 are embedded in an underground layer 120 of the roadway 106. In the example shown, the reflectors 104 are embedded in patterns 400a-400f. The patterns 400a-400f can include reflectors 104 having predefined three-dimensional spatial relationships. In the example shown, the patterns 400a-400f are embedded in the roadway and aligned with respective lanes. In some examples, the vehicle 100 can determine its alignment with a lane based on detecting the patterns 400a-400f. Different signals generated from different patterns 400a-400f are associated with different environmental data in a database and / or lookup table accessible to the active safety module 110. For example, one pattern 400a can be associated with a left lane identifier and another pattern 400b can be associated with a right lane identifier. As another example, one pattern 400c can be associated with a start of a school zone and another pattern 400d can be associated with an end of the school zone. As another example, one pattern 400e can be associated with a speed limit. As another example, a pattern 400f can be associated with a traffic signal 402. The patterns 400a-400f are located in proximity to the information that they represent.

[0024] Figure 5 is Figure 1 a block diagram of electronic components 500 of the vehicle 100. In the example shown, the electronic components 500 include the GPR system 102, the autonomous unit 108, the active safety module 110, an electronic control unit (ECU) 502, and a vehicle data bus 504.

[0025] The example GPR system 102 includes a processor or controller 506 and a memory 508. The processor or controller 506 can be any suitable processing device or set of processing devices, such as but not limited to: a microprocessor, a microcontroller-based platform, a suitable integrated circuit, a digital signal processor (DSP), a graphics processor, one or more field programmable gate arrays (FPGAs), and / or one or more application specific integrated circuits (ASICs). The memory 508 can be volatile memory (e.g., random access memory (RAM) that can include non-volatile RAM, magnetic RAM, ferroelectric RAM, and any other suitable form); non-volatile memory (e.g., disk storage, flash memory, electrically programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), non-volatile solid-state memory, etc.), unalterable memory (e.g., EPROM), read-only memory, and / or a high capacity storage device (e.g., a hard disk drive, a solid-state drive, etc.). In some examples, the memory 508 includes multiple types of memory, particularly volatile memory and non-volatile memory.

[0026] The memory 508 is a computer readable medium on which one or more sets of instructions, such as software for operating the methods of the present application, can be embedded. The instructions can embody one or more methods or logic as described herein. In particular embodiments, the instructions can reside entirely, or at least partially, within the memory 508, the computer readable medium, and / or the processor 506 during execution of the instructions.

[0027] The example active safety module 110 includes a processor or controller 510 and a memory 512. The processor or controller 510 can be any suitable processing device or set of processing devices, such as but not limited to: a microprocessor, a microcontroller-based platform, a suitable integrated circuit, one or more field programmable gate arrays (FPGAs), and / or one or more application specific integrated circuits (ASICs). The memory 512 can be volatile memory (e.g., RAM that can include non-volatile RAM, magnetic RAM, ferroelectric RAM, and any other suitable form); non-volatile memory (e.g., disk storage, flash memory, EPROM, EEPROM, non-volatile solid-state memory, etc.), unalterable memory (e.g., EPROM), read-only memory, and / or a high capacity storage device (e.g., a hard disk drive, a solid-state drive, etc.). In some examples, the memory 512 includes multiple types of memory, particularly volatile memory and non-volatile memory. In some examples, a database and / or lookup table for radar cross section pattern signals is stored in the memory 512.

[0028] Memory 512 is a computer readable medium on which is embedded one or more sets of instructions (such as can be embedded for software that operates the methods of the application). The instructions can embody one or more of the methods or logic as described herein. In particular embodiments, the instructions can reside entirely, or at least partially, within memory 512, the computer readable medium, and / or the processor 510 during execution thereof by the processor 510.

[0029] The terms "non-transitory computer-readable medium" and "tangible computer-readable medium" should be understood to encompass a single medium or multiple media, such as a centralized or distributed database, and / or associated caches and servers, which store one or more sets of instructions. The terms "non-transitory computer- readable medium" and "tangible computer-readable medium" also encompass any tangible medium that is capable of storing, encoding or carrying a set of instructions for execution by a processor or that cause a system to perform any one or more of the methods or operations disclosed herein. As used herein, the term "tangible computer-readable medium" expressly excludes propagating signals.

[0030] ECUs 502 monitor and control subsystems of vehicle 100. ECUs 502 communicate and exchange information via a vehicle data bus (e.g., vehicle data bus 504). Additionally, ECUs 502 can transmit characteristics (e.g., status of ECU 502, sensor readings, control status, error and diagnostic codes, etc.) to and / or receive requests from other ECUs 502. Some vehicles 100 can have seventy or more ECUs 502 communicatively coupled via vehicle data bus 504 in various locations around vehicle 100. ECUs 502 are discrete sets of electronics that include their own circuitry (such as integrated circuits, microprocessors, memory, storage devices, etc.) as well as firmware, sensors, actuators, and / or mounting hardware. ECUs 502 can include powertrain control units, body control units, steering wheel control units, and / or telematics units, among others.

[0031] Vehicle data bus 504 communicatively couples autonomous unit 108, active safety module 110, and ECUs 502. In some examples, vehicle data bus 504 includes one or more data buses. Vehicle data bus 504 can be in accordance with a Controller Area Network (CAN) bus protocol defined by International Standards Organization (ISO) 11898-1, a Media Oriented Systems Transport (MOST) bus protocol, a CAN Flexible Data (CAN-FD) bus protocol (ISO 11898-7), and / or a K-Line bus protocol (ISO 9141 and ISO 14230-1), and / or an Ethernet bus protocol (ISO 21802 and IEEE 802.3), among others. TMIt is implemented by bus protocols such as IEEE 802.3 (since 2002).

[0032] Figure 6 is to transmit infrastructure information to Figure 1 A flow chart of the method of the vehicle 100, which can be obtained by Figure 5 Initially, at block 602, the GPR system 102 broadcasts RF waves 112 and receives reflections from objects (such as reflectors 104) in the roadway 106 below the vehicle 100. At block 604, the GPR system 102 determines whether the reflections are indicative of a radar cross section (RCS) of one or more reflectors 104 (e.g., Figure 2 202, 204, and 206). When the detected RCS corresponds to one or more of reflectors 104, the method continues at block 606. Otherwise, when the detected RCS does not correspond to one or more of reflectors 104, the method returns to block 602.

[0033] At block 606, the GPR system 102 classifies the reflectors 104 into their different shapes (e.g., plates, spheres, tetrahedrons, etc.) based on the RCS detected at block 604. At block 608, the GPR system 102 determines the relative positions of the reflectors 104 in three-dimensional (3D) space. At block 610, the GPR system 102 generates a pattern of signals based on the shapes of the reflectors 104 and the relative positions of the reflectors 104 in 3D space. At block 612, the active safety module 110 determines environmental data associated with the signals generated at block 610. At block 614, the active safety module 110 shares the environmental data with other modules (e.g., autonomous unit 108, ECU 502, etc.) to control functions of the vehicle 100.

[0034] Figure 6 The flowchart represents a flow chart stored in a memory such as Figure 5 508 and 512) in the memory, the machine-readable instructions including when executed by a processor (e.g. Figure 5 When executed by the processor (CPU) 506 or 510 of the vehicle 100, Figure 1 and Figure 5 One or more procedures of the exemplary GPR system 102 and / or exemplary active safety unit 110. Furthermore, although reference is made to Figure 6 The flowchart shown describes an example procedure, but many other methods of implementing the example GPR system 102 and / or the example active safety unit 110 may alternatively be used. For example, the order of execution of the blocks may be changed, and / or some of the blocks described may be changed, eliminated, or combined.

[0035] In this application, the use of antonymous conjunctions is intended to include conjunctions. The use of definite or indefinite articles is not intended to indicate cardinality. In particular, reference to "the" object or "a" and "an" object is also intended to indicate one of a possible plurality of such objects. Moreover, the conjunction "or" can be used to convey the characteristics of alternatives that exist simultaneously rather than being mutually exclusive. In other words, the conjunction "or" should be understood to include "and / or". As used herein, the terms "module" and "unit" refer to hardware having circuitry that typically provides communication, control and / or detection capabilities in conjunction with sensors. "Module" and "unit" may also include firmware executed on the circuitry. The term "comprising" is inclusive and has the same scope as the respective "comprising".

[0036] The above embodiments, and particularly any "preferred" embodiments, are possible examples of implementations and are merely set forth for a clear understanding of the principles of the invention. Many variations and modifications may be made to the above embodiments without materially departing from the spirit and principles of the technology described herein. All modifications are intended to be included herein within the scope of this disclosure and protected by the following claims.

Claims

1. A vehicle comprising: an antenna positioned to broadcast radio waves beneath the vehicle; A ground penetrating radar system, the ground penetrating radar system being used for: determining shapes of reflectors and spatial relationships between the reflectors based on a radar cross section detected by the antenna, wherein the reflectors are embedded in a subsurface layer of a roadway, wherein the reflectors are positioned in a predefined three-dimensional pattern, providing the spatial relationships, a GPR system uniquely identifying the cross-sections of the reflectors and the spatial relationships to generate a signal corresponding to environmental data, wherein each reflector in the spatial relationship has one or more components in at least one of an x-axis, a y-axis, and a z-axis; as well as generating a signal based on the shape and the spatial relationship; as well as An active safety module, wherein the active safety module is used to: comparing the detected pattern to a list of known patterns; determining environmental data based on the comparison; and The vehicle is autonomously controlled based on the environmental data. 2 . The vehicle according to claim 1 , wherein the radio waves have a frequency between 10 MHz and 2.4 GHz. The vehicle of claim 1 , wherein the radar cross section is indicative of at least two types of the reflectors. The vehicle of claim 1 , wherein the antenna detects the reflector embedded in an underground layer of a road. 5 . The vehicle of claim 1 , wherein the environmental data includes at least a direction of travel and a lane identifier for a portion of a road on which the vehicle is traveling. 6 . The vehicle of claim 1 , wherein the signal corresponds to the environmental data including one of traffic signal information, speed limit information, or warning information.

7. The vehicle of claim 1, wherein the radar cross section is caused by the reflector being selected from the group consisting of a flat plate, a sphere, and a tetrahedron. 8 . The vehicle of claim 1 , wherein the spatial relationship is a three-dimensional spatial relationship indicating that at least two of the reflectors are embedded at different depths in a subsurface layer of a road.

9. A method for a vehicle, comprising: using a ground penetrating radar antenna secured to a vehicle to broadcast radio waves beneath the vehicle; determining, using a processor, shapes of reflectors and spatial relationships between the reflectors based on radar cross sections detected by the antennas, wherein the reflectors are embedded in a subsurface layer of a roadway, wherein the reflectors are positioned in a predefined three-dimensional pattern, providing the spatial relationships, a GPR system uniquely identifying the cross sections of the reflectors and the spatial relationships to generate a signal corresponding to the environmental data, wherein each reflector in the spatial relationship has one or more components in at least one of an x-axis, a y-axis, and a z-axis; as well as generating a signal based on the shape and the spatial relationship; comparing the detected pattern to a list of known patterns; as well as determining environmental data based on the comparison; as well as The vehicle is autonomously controlled based on the environmental data.

10. The method of claim 9, wherein the radio waves have a frequency between 10 MHz and 2.4 GHz. The method of claim 9 , wherein the radar cross section is indicative of at least two types of the reflectors.

12. The method of claim 9, comprising detecting the reflector embedded in a subsurface layer of a roadway.

13. The method of claim 9, wherein the environmental data includes at least a direction of travel and a lane identifier of a portion of a road on which the vehicle is traveling.

14. The method of claim 9, wherein the radar cross section is caused by the reflector being selected from the group consisting of a flat plate, a sphere, and a tetrahedron.

15. The method of claim 9, wherein the spatial relationship is a three-dimensional spatial relationship indicating that at least two of the reflectors are embedded at different depths in a subsurface layer of a roadway.

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