Vehicle guidance using IMU and radar with reflective targets located on or near driving surface

Abstract

An apparatus for guiding a land vehicle along a path on which one or more side targets having different radar reflectance characteristics than the path are present. The apparatus includes a radar sensor, a processor, and an inertial measurement unit (IMU). The radar sensor is mounted to the vehicle and is configured to radiate one or more signals to the path, the signals having a main beam pattern center directed toward the ground and laterally from the vehicle. The radar sensor is further configured to detect one or more reflected signals from one or more side targets along the path. The processor is configured to determine a lateral distance between the vehicle and the side target based on the reflected signal when the vehicle passes or first encounters the side target. The IMU is configured to determine a change in a lateral position of the vehicle between the side targets.

Description

Related applications

[0001] This application claims priority to the following U.S. provisional patent applications: (1) U.S. Application No. 63 / 543,444, filed October 10, 2023, entitled “Radar-Based and IMU-Based Vehicle Guidance using RadarReflectors Embedded in Pavement Markers on a Driving Surface”; (2) U.S. Application No. 63 / 605,500, filed December 2, 2023, entitled “Radar-Based and IMU-Based Vehicle Guidance using Radar Reflectors Embedded in Pavement Markers on a Driving Surface”; and (3) U.S. Application No. 63 / 683,882, filed August 16, 2024, entitled “Radar-Based Vehicle Guidance Using Reflectivity of Targets on or Near the Driving Surface”. The entire disclosure of each of the above priority patent applications is incorporated herein by reference.

[0002] The subject matter of this application also relates to the following patent applications filed by the applicant: (1) International Patent Application No. PCT / US2023 / 028710, entitled “Radar-Based Vehicle Guidance Using Radar Reflectors Embedded in Pavement Markers on a Driving Surface,” filed July 26, 2023, claiming priority to each of the following U.S. Provisional Patent Applications: (a) No. 63 / 474,257, filed August 1, 2022, entitled “Vehicle Guidance System”; (b) No. 63 / 474,383, filed August 10, 2022, entitled “Vehicle Guidance System”; (c) No. 63 / 576,322, filed January 30, 2023, entitled “Short-Range Radar for use in Vehicle Lateral Guidance and (d) No. 63 / 576,323, filed January 30, 2023, entitled “Vehicle Guidance System”; (e) No. 63 / 454,669, filed March 25, 2023, entitled “Radar-Based Vehicle Guidance System Using Dihedral Corner Reflector Embedded in Pavement Marker”; (f) No. 63 / 464,532, filed May 5, 2023, entitled “Vehicle Guidance System”; (g) No. 63 / 464,527, filed May 5, 2023, entitled “Short-Range Radar for Lateral Navigation and Control of Vehicles”; (h) No. 63 / 466,612, filed May 15, 2023, entitled “Vehicle Guidance System”. System”; and (i) No. 63 / 469,920 filed on May 31, 2023, entitled “Radar-Based Vehicle Guidance Using Corner Reflectors Embedded in Pavement Markers on a Driving Surface”; and (2) International Patent Application No.PCT / US2024 / 027899, entitled "Radar-Based Vehicle Guidance Using Arrays of Reflectors Embedded in or Under a Road Line on a Driving Surface," filed May 4, 2023, claims priority, as does U.S. Provisional Patent Application No. 63 / 470,102, entitled "Radar-Based Vehicle Guidance Using Array of Corner Reflectors Embedded in or Under a Line on a Driving Surface," filed May 31, 2023. The entire disclosure of all of the above patent applications is incorporated herein by reference. Technical Field

[0003] The scope of this disclosure generally relates to the control of automobiles or similar land vehicles. More specifically, this disclosure relates to controlling or assisting in the control of vehicles using the reflectivity of radar (radio detection and ranging) targets located on or near roads or other driving surfaces, particularly the lateral positioning of vehicles. Background Technology

[0004] Radar has been used in automobiles for a variety of purposes, such as blind spot detection and forward collision warning. However, radar is not routinely used to perform or assist in performing lateral steering of a vehicle. In fact, electronic lateral steering or steering assist systems typically collect and process visual data. This method is complex and is limited or unavailable in adverse weather conditions (such as rain, snow, ice, fog), smoke, and darkness.

[0005] Road lines and pavement markings are typically deployed on or near the driving surface to demarcate road or lane boundaries. Shoulders, concrete barriers, and other roadside objects sometimes also distinguish the edges of roads or lanes. Summary of the Invention

[0006] This disclosure generally relates to the use of radar sensors or transceivers and inertial measurement units (IMUs) on or in land vehicles to perform lateral steering or assist in performing lateral steering, such as lane-based ADAS functions. At least one radar sensor is mounted on the vehicle and oriented to emit radar signals laterally downwards and from the side of the vehicle, and receives reflected signals from side targets on or near the side of the road or lane. These side targets can be, for example, conventional road markings, improved road markings with enhanced radar reflectivity, road shoulders, concrete obstacles, signposts, etc. As the vehicle passes each target, the round-trip time of flight of the radar signal to and from the side target can provide accurate lateral distance measurements and thus lateral vehicle position information for steering, steering assistance, or lateral position checking. Between intermittently spaced side targets, various types of information from the IMU can be used to determine lateral position information for the vehicle. Thus, the combination of radar sensors and IMUs can provide continuous or near-continuous lateral vehicle position information along a road or lane with intermittently radar-reflecting side targets.

[0007] According to one embodiment, an apparatus guides a land vehicle along a path in which one or more side targets having radar reflectivity characteristics different from the path are positioned. The apparatus includes a radar sensor, a processor, and an IMU. The radar sensor is mounted to the vehicle and is aimed downwards and laterally toward the vehicle. The radar sensor is configured to radiate one or more signals toward the path via at least one transmitter, the one or more signals having a main beam pattern center aimed toward the ground and laterally toward the vehicle. The radar sensor is also configured to detect one or more reflected signals from the one or more side targets along the path via one or more receiving antennas. The processor is operatively connected to the radar sensor. The processor is configured to determine the lateral distance between the vehicle and the side target based on the reflected signals when the vehicle passes by or first encounters a side target. The IMU is configured to determine changes in the lateral position of the vehicle between the side targets.

[0008] Optionally, the radar sensor operates in a frequency range from about 300 MHz to about 1 THz or from about 77 GHz to about 81 GHz.

[0009] Alternatively, the radar sensor is a frequency-modulated continuous wave radar transceiver, an ultra-wideband pulse radar transceiver, or a type selected from the group consisting of dual-frequency phase difference radar, multi-frequency radar, multi-frequency phase radar, orthogonal frequency division multiplexing radar, frequency shift keying radar, digitally coded modulation radar, phase-modulated continuous wave radar, multiple-input multiple-output radar, polarized radar, dual-polarized radar, monopulse radar, noise radar, and interferometric synthetic aperture radar.

[0010] Radar sensors can be, for example, monostatic or bi-static.

[0011] Optionally, the radar sensor includes an antenna array configured to transmit polarized radar signals, configured to detect reflected signals based on its polarization, configured to be placed on or inside the front bumper of the vehicle, and / or encapsulated in the headlight assembly.

[0012] Alternatively, the processor is configured to process only a portion of the reflected signal received in a window corresponding to the desired range of the reflecting target, or to perform a frequency transformation of the reflected signal.

[0013] Alternatively, the side target may be selected from the group consisting of raised pavement markings, raised pavement markings with bifacial reflectors, snowplowable pavement markings, snowplowable pavement markings with bifacial reflectors, road ditches, path slots, road signs, mailboxes, road shoulders, concrete obstacles, road shoulders, streetlights, fire hydrants, trees, and path edges.

[0014] Optionally, the IMU includes an accelerometer that provides lateral acceleration, which is integrated twice to provide the change in the lateral position of the vehicle between targets.

[0015] Optionally, the IMU includes a gyroscope that provides the yaw rate, and it is integrated once to provide the change in the vehicle's heading, and the change in heading is used to determine the change in the vehicle's lateral position between targets.

[0016] Optionally, the IMU includes a magnetometer that provides the vehicle's orientation, and this orientation is used to determine changes in the vehicle's lateral position between targets.

[0017] Alternatively, a complementary filter or a Kalman filter can be used to combine the lateral range from the radar sensor with the lateral position variation from the IMU.

[0018] According to another embodiment, a vehicle is designed for use on a road with multiple side targets along the road. Each side target is characterized by its radar reflectivity. The vehicle includes a first lateral side, a radar transceiver mounted to the vehicle, a processor, and an IMU. The radar transceiver is characterized by a main beam pattern that is downward and centered, aimed from the side of the vehicle, such that reflections are detected by the radar reflectivity of the side targets as the vehicle moves forward past them on the first lateral side. The processor is operatively coupled to the radar transceiver and configured to determine the path length from the radar transceiver to the side targets based on the reflections. The IMU is configured to determine changes in the lateral position of the vehicle between the side targets.

[0019] Optionally, the vehicle also includes a second lateral side opposite to the first lateral side, and the main beam pattern is a first main beam pattern having a first center aimed downwards in the direction from the first side of the vehicle, the side target being a first side target on the first lateral side of the vehicle, and the radar transceiver is further characterized by a second main beam pattern having a second center aimed downwards in the direction from the second side of the vehicle, such that when the vehicle moves past the second side target, a reflection is detected from a second radar reflector embedded in the second side target. The second lateral direction is substantially horizontally opposite to the lateral direction, and the second side target is located on the second lateral side of the vehicle.

[0020] Optionally, the radar transceiver is a first radar transceiver, the main beam pattern is a first beam pattern having a first center aimed downwards in a direction from a first side of the vehicle, and the side target is a first side target located on the first lateral side of the vehicle, and the vehicle also includes a second radar transceiver mounted to the vehicle. The second radar transceiver is characterized by a second main beam pattern having a second center aimed downwards in a direction from a second side of the vehicle, such that reflections are detected from the radar reflectivity of the second side target when the vehicle moves forward past the second side target located on the first lateral side of the vehicle.

[0021] Optionally, the vehicle also includes an external light assembly, and the radar transceiver is located on or in the external light assembly.

[0022] Optionally, the vehicle also includes a front bumper, and the radar transceiver is located on or inside the front bumper.

[0023] Optionally, the processor is configured to perform or assist in performing one or more of the lane departure warning function, lane keeping function, and lane centering assist function based on the path length from the radar transceiver to the side target.

[0024] Optionally, the vehicle also includes a lateral positioning system independent of the radar transceiver, wherein the radar transceiver and the processor form a redundant lateral positioning system.

[0025] Optionally, the vehicle is at least partially autonomous and performs lateral positioning of the vehicle at least in part based on the path length from the radar transceiver to the side target.

[0026] Optionally, the radar transceiver is also configured to perform blind spot detection or cross-traffic detection.

[0027] According to another embodiment, a method determines the lateral position of a land vehicle along a path. The path includes side targets with radar reflectivity characteristics different from the path itself. The side targets are arranged along the path in the vehicle's direction of travel. As the vehicle passes a side target, the method transmits radar signals downwards and from the side of the land vehicle toward the side target, which is mounted on or near the path. As the vehicle passes a side target, the method receives radar reflected signals from the side target at the land vehicle. The method determines the distance between the land vehicle and the side target based on the radar transmitted and reflected signals. The method determines the change in the vehicle's lateral position between the side targets based on one or more inertial measurements. The method determines the approximate lateral position of the vehicle between the side targets based on the change in lateral position and the distance between the land vehicle and the passed side targets.

[0028] Optionally, the steps of repeatedly transmitting radar signals, receiving radar reflection signals, and determining distances are repeated for essentially each radar-reflective side target that the vehicle passes through.

[0029] Optionally, the emission steps are repeated periodically at a period selected from approximately 0.5 milliseconds to approximately 1 second.

[0030] Alternatively, as the vehicle travels along the path, the side targets are distributed along one side of the vehicle.

[0031] Optionally, the path is one lane of a multi-lane road, and the side target is a road marking distributed along a line that divides one side of the path.

[0032] Optionally, the path is a lane of a multi-lane road, and the side target is a road marking distributed along a line that divides the lane adjacent to the lane corresponding to the path of the same vehicle.

[0033] Optionally, the method also filters radar reflection signals based on the range of expected distances between the land vehicle and the side target.

[0034] Optionally, the method also performs frequency conversion on the radar reflection signal.

[0035] Optionally, the method also uses distance to guide or assist lateral steering vehicles in following the path.

[0036] Optionally, if the distance exceeds a maximum threshold or is less than a minimum threshold, or if the approximate lateral position is outside an acceptable range, the method issues a warning to the driver and / or the exterior of the vehicle. Warnings to the exterior of the vehicle may include, for example, flashing turn signals.

[0037] Optionally, the method may also perform one or more of lane centering assist and lane keeping functions based on the distance between the land vehicle and the side sign.

[0038] Optionally, the vehicle includes a lateral positioning system independent of the method described above, and the method is further combined with the independent lateral positioning system to use distance to improve lateral position determination. The lateral positioning system may include, for example, a global navigation satellite system, a visual system that observes paint lines along a path, or a lidar system that observes paint lines along a path, or a recorded target along the path.

[0039] According to another embodiment, a group of one or more radar transceivers is configured to be mounted in or on a land vehicle for observing radar-reflective side targets along a path along which the land vehicle may travel. The group includes a radar transmitter and a radar receiver. The radar transmitter is configured to transmit radar signals from a plurality of transmit antennas horizontally mounted along the lateral side of the vehicle. The antennas include a transmit beam pattern having a maximum transmission center direction. The radar receiver is configured to receive radar return signals at one or more receive antennas horizontally mounted along the lateral side of the vehicle. The antennas are configured to include a receive beam pattern having a maximum reception center direction. The radar transceivers are configured to be mounted on or in the land vehicle such that, when the group is mounted on or in the land vehicle, the maximum transmission center direction is downward and from the land vehicle to the side, and the maximum reception center direction is upward and lateral towards the land vehicle. Multiple transmitting antennas are spaced longitudinally along the vehicle such that each side target is within the transmitting beam pattern of at least one transmitting antenna, and multiple receiving antennas are spaced longitudinally along the vehicle such that each side target is within the receiving beam pattern of at least one antenna when the vehicle passes the side target.

[0040] Optionally, multiple transmitting antennas are the same as multiple receiving antennas, and each antenna is a transmitting / receiving antenna.

[0041] According to another embodiment, a vehicle is designed for use on a road, along which multiple side targets have been mounted. Each side target is characterized by its RF reflectivity. The vehicle includes a first radar transceiver, a second radar transceiver, and a processor. The first radar transceiver is mounted at or near the front of the vehicle, characterized by a first main beam pattern having a first center pointing downwards and laterally from the vehicle, thereby detecting reflections from the RF reflectivity of the side targets as the vehicle moves forward past them. The second radar transceiver is mounted at or near the rear of the vehicle, characterized by a second main beam pattern having a second center pointing downwards and laterally from the vehicle, thereby detecting reflections from the RF reflectivity of the side targets as the vehicle moves forward past them. The processor is operatively coupled to the radar transceivers and configured to determine the path length from each radar transceiver to the side target based on reflections from the two radar transceivers.

[0042] Optionally, the processor is further configured to determine the vehicle's heading information and its lateral deviation along the road relative to a side target. Attached Figure Description

[0043] Figure 1A This is a front view of a vehicle equipped with two radar transceivers (including another vehicle) that interact with a side target located on a driving surface and along the side of a road, according to one embodiment.

[0044] Figure 1B This is a front view of a vehicle equipped with a two-way radar transceiver (including another vehicle) that interacts with a side target located on the driving surface and along the side of the road, according to another embodiment.

[0045] Figure 2 This is a top view of a vehicle equipped with a radar transceiver and an inertial measurement unit on a road with road markings, according to one embodiment.

[0046] Figure 3 This is a block diagram of a system combining multiple detection, guidance, and / or control systems (including a radar-based lateral positioning system) according to one embodiment.

[0047] Figure 4A It is a three-dimensional representation of traditional road markings.

[0048] Figure 4B It is a top view of a road section with traditional pavement markings placed on it.

[0049] Figure 5A This is a front view of road markings according to one embodiment, showing reflections from / to a radar transceiver.

[0050] Figure 5B This is a front view of another road marking according to one embodiment, showing reflections from / to a radar transceiver.

[0051] Figure 6A This is a three-dimensional diagram of a bifacial reflector.

[0052] Figure 6B This is a perspective view of a road marking enhanced with two dihedral reflectors according to one embodiment.

[0053] Figure 6C yes Figure 6B A top view of the road markings.

[0054] Figure 6D yes Figure 6B Side view of the road markings.

[0055] Figure 7A It is a cross-sectional view of a cavity in or beneath a driving surface according to one embodiment.

[0056] Figure 7B According to one embodiment, there are already arranged Figure 7A A top view of the road section of the cavity.

[0057] Figure 7C According to another embodiment, in which there are already arranged Figure 7A A top view of the road section of the long cavity.

[0058] Figure 8A This is a cross-sectional view of road markings located within a cavity below the driving surface according to one embodiment, showing reflections from / to a radar transceiver.

[0059] Figure 8B According to one embodiment, there are already arranged Figure 8A A top view of a section of the road with pavement markings.

[0060] Figure 8C According to another embodiment, in which there are already arranged Figure 8A A top view of a section of the road with pavement markings.

[0061] Figure 9 This is a front view of a snowplowable pavement marking according to one embodiment.

[0062] Figure 10A This is a perspective view of a road shoulder according to one embodiment, showing reflections from / to a radar transceiver.

[0063] Figure 10BThis is a schematic diagram illustrating a road shoulder according to one embodiment, showing reflections from / to a radar transceiver.

[0064] Figure 10C This is a front view of a concrete obstacle according to one embodiment, showing reflections from / to a radar transceiver.

[0065] Figure 10D This is a schematic diagram illustrating road markings and roadside vegetation according to one embodiment.

[0066] Figure 10E This is a schematic diagram illustrating road markings and roadside signs according to one embodiment.

[0067] Figure 10F This is a schematic diagram illustrating a street shoulder according to one embodiment.

[0068] Figure 10G This is a side view of a concrete obstacle according to one embodiment, showing reflections from / to a radar transceiver.

[0069] Figure 11A This is a top view of two vehicles equipped with radar transceivers according to one embodiment, illustrating the interaction between range / range-based gating and radar-reflective pavement markings and other target structures on a multi-lane road.

[0070] Figure 11B This is a top-view schematic diagram of two vehicles equipped with radar transceivers according to one embodiment, illustrating range / range-based gating that utilizes vehicle dynamics modeling to interact with radar-reflected pavement markings and other target structures on a multi-lane road.

[0071] Figure 11C This is a top-view schematic diagram of two vehicles equipped with radar transceivers according to one embodiment, illustrating the interaction between time-based gating and radar-reflective pavement markings and other target structures on a multi-lane road.

[0072] Figure 12A This is a graph of received radar range versus time according to one embodiment, illustrating gating based on amplitude and range / range.

[0073] Figure 12B This is a graph of received radar amplitude versus time according to one embodiment, illustrating gating based on amplitude and range / range.

[0074] Figure 12C This is a filtered received distance versus time graph according to one embodiment, illustrating gating based on amplitude and range / range.

[0075] Figure 13This is a block diagram of a radar-based LDW / LKA / LKS system for a vehicle according to one embodiment.

[0076] Figure 14 This is a block diagram of a radar transceiver that combines other sensors with complementary filters according to one embodiment.

[0077] Figure 15 This is a block diagram of a radar transceiver that combines other sensors with complementary filters according to another embodiment.

[0078] Figure 16 This is a block diagram of a radar transceiver that combines other sensors using a Kalman filter according to one embodiment.

[0079] Figure 17A This is a timing diagram showing the lateral distance from a radar transceiver mounted on a moving vehicle to a side target along the road, according to one embodiment.

[0080] Figure 17B This is a schematic diagram illustrating the lateral distance from a radar transceiver fused with an IMU mounted on a moving vehicle to a side target along a road, according to one embodiment.

[0081] Figure 18 This is a block diagram of a radar-based LDW / LKA / LKS system for a vehicle according to one embodiment.

[0082] Figure 19 This is a block diagram of a radar transceiver that combines other sensors using a Kalman filter according to one embodiment.

[0083] Figure 20 This is a top view of a vehicle traveling along a road according to one embodiment, showing the vehicle-road geometry and the use of multiple radars.

[0084] Figure 21 This is a top view of a vehicle traveling along a road according to one embodiment, showing the vehicle-road geometry and the use of a single radar.

[0085] Figure 22 This is a block diagram of a radar-based LDW / LKA / LKS system for a vehicle according to one embodiment.

[0086] Figure 23 This is a block diagram of a radar-based automatic lateral control system for a vehicle according to one embodiment.

[0087] Figure 24 This is a block diagram of a radar-based autonomous lateral control system for a vehicle according to another embodiment.

[0088] Figure 25This is a top view of two vehicles equipped with radar transceivers that interact with radar-reflective road markings on a multi-lane road, according to one embodiment.

[0089] Figure 26 This is a top view of a vehicle equipped with a radar transceiver that interacts with radar-reflective pavement markings on a curved road, according to one embodiment.

[0090] Figure 27 This is a top view of a vehicle equipped with a radar transceiver that interacts with radar-reflective pavement markings on a curved road, according to another embodiment.

[0091] Figure 28 This is a top view of a vehicle equipped with a side-looking radar transceiver according to one embodiment, having multiple antennas interacting with radar-reflective pavement markings on the road.

[0092] Figure 29 This is a top view of a vehicle equipped with a side-looking radar transceiver according to another embodiment, having multiple radar transceivers interacting with radar-reflective pavement markings on the road.

[0093] Figure 30 This is a schematic diagram of a radar transceiver array according to one embodiment.

[0094] Figure 31 This is a block diagram of a radar transceiver having multiple transmit / receive antennas according to one embodiment.

[0095] Figure 32 This is a block diagram of a radar transceiver with multiple transmit / receive antennas according to another embodiment.

[0096] Figure 33 This is a block diagram of multiple radar transceivers according to one embodiment.

[0097] Figure 34 This is a timing diagram of the output of a radar transceiver having multiple transmit / receive antennas according to one embodiment. Detailed Implementation Preliminary notes

[0098] Exemplary embodiments are described below with reference to the accompanying drawings. Unless otherwise expressly stated, the dimensions, positions, etc., of the components, features, elements, etc., and any distances between them in the drawings are not necessarily drawn to scale and may be disproportionate and / or exaggerated for clarity.

[0099] The terminology used herein is for describing particular exemplary embodiments only and is not intended to be limiting. The singular forms “a,” “an,” and “the” used herein are intended to include the plural forms unless the context clearly indicates otherwise. It should be understood that the terms “comprising,” “including,” “containing,” “including,” “comprising,” “containing,” “having,” “with,” and “having” as used in this document specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Unless otherwise specified, when enumerating range values, the range values ​​include the upper and lower limits of the range and any subranges therein. Unless otherwise stated, terms such as “first,” “second,” etc., are used only to distinguish one element from another and do not imply any relative order, placement, or hierarchy. For example, one element may be referred to as “first element,” and similarly, another element may be referred to as “second element,” or vice versa. Section headings used herein are for organizational purposes only and should not be construed as limiting the subject matter.

[0100] Unless otherwise stated, terms such as “approximately,” “around,” “substantially,” “generally,” “approximately” indicate quantities, dimensions, formulations, parameters, and other quantities and characteristics that need not be precise and may be substantially the same and / or larger or smaller as required, reflecting tolerances, conversion factors, rounding, measurement errors, and other factors known to those skilled in the art.

[0101] This document uses spatial relative terms such as “right,” “left,” “forward,” “backward,” “below,” “under,” “lower,” “above,” and “upper” to describe the relationship of one element or feature relative to another element or feature, as illustrated in the figures. It should be understood that spatial relative terms are intended to include different orientations in addition to those shown in the figures. For example, if the objects in the figures are flipped, an element described as “below” or “under…” will face other elements or features “above.” Therefore, the term “below / under” can, for example, encompass both above / above and below / below orientations. Objects may be oriented in other ways (e.g., rotated 90° or otherwise), and the spatial relative descriptors used herein can be interpreted accordingly.

[0102] As used herein, the terms “RF” and “radio” refer to or imply electromagnetic radiation in the frequency range that is electronically detected and processed. For example, the RF spectrum includes very low frequencies (VLF, e.g., about 3 kHz) and can extend just below infrared (e.g., about 300 THz). The RF spectrum includes very low frequency (VLF), low frequency (LF), intermediate frequency (MF), high frequency (HF), ultra-high frequency (VHF), very high frequency (UHF), extremely high frequency (SHF), and extra-high frequency (EHF) bands. The RF spectrum also includes microwave and millimeter-wave bands.

[0103] The concepts and innovations described in this paper with reference to RF or radio frequency radiation and / or radar can also be realized with other types of radiation or waves, including, for example, infrared, visible light, ultraviolet light, lasers, LIDAR, and sonar, with appropriate modifications to the transceivers and reflectors.

[0104] Unless otherwise expressly stated, all connections and couplings may be direct (without middleware) or indirect (with one or more middleware). All operational connections and couplings may be made electronically in hardware or logically in software unless otherwise expressly stated. Similarly, unless otherwise expressly stated, all physical connections and couplings may be rigid or non-rigid, permanent or detachable.

[0105] Throughout the text, the same symbols denote the same elements. Therefore, even if not mentioned or described in the corresponding figures, the same or similar reference numerals may be used to describe them with reference to other figures. Furthermore, elements not indicated by reference numerals may be described with reference to other figures. In addition, the figures may include non-essential elements included solely for the sake of thoroughness. These non-essential elements may be completely removed or only their outlines retained if changes to the figures are desired to achieve greater clarity.

[0106] The embodiments described herein are merely examples and are given by way of illustration only and not by way of limitation. Those skilled in the art will recognize from the teachings herein that alternatives, variations, and equivalents exist for the exemplary implementations and components thereof described herein. For example, other embodiments are readily achievable, modifications can be made to the embodiments described herein, and there may be alternatives equivalent to the components, parts, or steps constituting the embodiments described.

[0107] For the sake of clarity and brevity, specific aspects of the components or steps of a particular embodiment are shown without excessive detail where they would be obvious to those skilled in the art based on the teachings herein and / or where the details described would obscure the understanding of a more relevant aspect of the embodiments.

[0108] The foregoing descriptions of embodiments of the present invention are not intended to limit the invention. Although several specific exemplary embodiments have been described, those skilled in the art will readily understand that many modifications and other embodiments are possible to the disclosed exemplary embodiments without significantly departing from the novel teachings and advantages of the invention. Therefore, all such modifications are intended to be included within the scope of the invention as defined in the appended claims. For example, those skilled in the art will understand that, in cases where such combinations are mutually exclusive, the subject matter of any sentence or paragraph may be combined with the subject matter of some or all of other sentences or paragraphs.

[0109] Those skilled in the art will recognize that many changes can be made to the details of the above embodiments without departing from the basic principles of the invention described herein. Down-looking radar with IMU and other sensors

[0110] Figure 1A Two vehicles, 180 and 182, are shown on a typical road 300. Vehicle 180 has side radar transceivers 116 and 117 for detecting targets on the road, such as road markings, road troughs, road ditches, other vehicles, and roadside structures such as street shoulders, road signs, concrete obstacles, guardrails, mailboxes, trees, fire hydrants, lampposts, etc. As shown, radar transceiver 117 on vehicle 180 is looking downwards and sideways to see street shoulder 1420 and sideways to observe road sign 1306.

[0111] Radar transceiver 116 on the same vehicle 180 observes the road marking 445 at the center of road 300 and also observes vehicle 182 along the side of the vehicle. Radar transceiver 116 uses radar beam 1108 to observe the road marking and radar beam 1106 to observe vehicle 182, as shown. Similarly, radar transceiver 117 uses radar beam 1109 to observe the street shoulder and radar beam 1107 to observe road sign 1306. Alternatively, radar transceiver 116 may have a single wider beam capable of seeing both vehicle 182 and road marking 445, and radar transceiver 117 may have a single wider beam covering both beams 1107 and 1109. Radar transceivers 116 and 117 may have single or multiple beams, and their beamwidths are parameters that can be selected as needed by those skilled in the art.

[0112] Radar beams 1106, 1107, 1108, and 1109 can be fixedly oriented to the side and downward, alternatively observing targets, turning between different targets, or adjusted according to a database of roadside targets. Radar transceivers 116 and 117 can observe many different roadside targets and track them simultaneously or efficiently synchronously, achieved by looking downward and to the side at or near the road, by looking downward and to the side near the side of the road, and by looking only to the side near the side of the road. When vehicle 180 passes vehicle 182, radar transceiver 116 on vehicle 180 can also facilitate the determination of lateral distance 1811 between vehicle 180 and 182. Vehicle 182 typically obstructs the view of radar transceiver 116 on vehicle 180 from observation of distant roadside targets (e.g., concrete obstacles). When available, the lateral distance 1811 information, in addition to observing fixed roadside targets, provides a more robust control system.

[0113] Figure 1A Other sensors are also shown, such as an IMU (Inertial Measurement Unit) 907, a GNSS (Global Navigation Satellite System) receiver 901, and a visual sensor 903. These sensors can provide lateral and longitudinal range information when radar transceivers 116 and 117 are not observing targets for lateral or longitudinal range information.

[0114] Figure 1B The radar transceiver 119 is shown mounted at the center front of the vehicle 180 to observe the road and roadside targets from two directions (i.e., opposite lateral directions, right and left, or driver's side and passenger side) via two antennas. In this embodiment, the radar transceiver 119 is similar to... Figure 1A Those in the configuration use radar beams 1106-1109 to observe targets. Two advantages of this mounting scheme compared to mounting separate radar transceivers 116 and 117 on the front are: (1) cost savings with only one unit; and (2) the observation range allows the vehicle 180 to cross targets on or within the lane boundary line or aligned with the lane boundary line (e.g., road marking 445) while still tracking the target.

[0115] Figure 2Another embodiment is shown in which multiple radar transceivers 117, together with IMU 907, can be mounted in multiple locations on the left side of vehicle 180, and similarly, one or more radar transceivers 116, together with IMU 907, can be mounted on the right side of vehicle 180. Radar transceivers 116 and 117 can be mounted in side marker lights, headlights, fog lights, daytime running lights, or turn signals on the vehicle, or mounted under covers or inside housings for these lights, for example, to minimize impact on the exterior design. Radar transceivers 116 and 117 can be mounted on or in the bumper (e.g., front bumper) of vehicle 180. Radar transceivers 116 and 117 can be mounted on the exterior rear of vehicle 180 made of RF transparent material (typically plastic and / or fiberglass) (e.g., behind a body panel). In another embodiment, one or more radar transceivers 117 will see road marking 1284 on the left, and one or more radar transceivers 116 will see road marking 284 on the right. Furthermore, radar transceivers 119 and IMU 907 can be mounted at the center front of the vehicle 180 and will be able to see in two directions, relative to road markings 284 and 1284, to the left and right sides of the vehicle 180. These additional radar transceivers can provide redundancy, heading angle information, and more timely distance measurements. Many other combinations are possible, mounting one or more radar transceivers on the vehicle 180 to provide more robust lateral guidance control.

[0116] The IMU 907 surrounding vehicle 180 may be part of or a separate unit of radar transceivers 116, 117, and 119. A separate IMU is also shown at the center of vehicle 180. IMU 907 can provide changes in distance measurements to the last side target observed by the radar transceiver. Therefore, when IMU information (i.e., inertial measurement) is fused with radar transceiver information, distance measurements between side targets, such as road markings 284 and 1284, can be determined continuously, quasi-continuously, or approximately continuously, or at discrete points between side targets. As used herein, the phrase "inertial measurement" refers to any data that an IMU can generate. Examples of inertial measurements include acceleration, yaw rate, heading, and changes in the aforementioned items.

[0117] For redundancy and / or higher reliability, the radar guidance technology described herein can be combined with other guidance technologies based on other technologies. For example, radar transceivers 116 and 117 can be integrated with other sensors, such as GNSS receiver 901, lidar sensor 902, vision sensor 903, forward-looking radar 904, IMU 907, steering wheel angle sensor 8028, vehicle speed sensor 8008, or other positioning sensors 905, such as... Figure 3As shown. As another example, signal processing from multiple sensors, including the radar sensors described herein, can be performed by a general-purpose processor or computer (which may have multiple processors). Joint processing of various sensor types can improve the performance of any single sensor type individually. For example, the output of an airborne processor 437 using one or more Kalman filters can provide more reliable positioning information 914, steering information 912, and speed information 918. Targets on the road and along the roadside

[0118] Figure 4A and 4B The image shows a typical pavement marking 445 currently in use on the current road. Figure 4A The pavement marking 445 shown is rectangular, but pavement markings come in many different shapes and sizes. Pavement markings 445 can be placed on top of the pavement, in which case they are referred to as raised pavement markings (RPMs), or pavement markings 445 can be installed at or slightly below the pavement surface level (e.g., snowplow markings), or located below the road surface 300 in cut grooves, pits, or slots. Pavement markings 445 are typically installed along or aligned with lane boundary lines, such as lines 305, 307, and 309 painted on the road 300, as shown below. Figure 4B As shown. Painted line 307 is typically a yellow center line, while white lines 305 and 309 mark the sides (road edges). The primary function of road marking 445 is to reflect light waves, allowing vehicle headlights or daytime running lights to be reflected back to the driver, making it easier for the driver to see the road markings, especially in inclement weather. Road markings have one or more visible reflectors 275 on the sides, such as... Figure 4A As shown. Furthermore, when a vehicle crosses a road line or pavement marking 445, the raised pavement reflector acts as a rumble guard, because marking 445 is typically 25mm above the road surface and causes the vehicle's tires to impact the raised pavement marking. Over the years, raised pavement markings 445 have undergone numerous improvements, incorporating various visible reflective properties such as cat's eye, LED (light-emitting diode) lights, and lidar reflective modes. Pavement markings 445 are highly reflective of visible light, and they may or may not reflect radio frequency (RF) radiation from radar transceivers, although they have not traditionally been intentionally designed to be RF reflective. Pavement markings are commonly used on roads, but are also used in parking lots, freight yards, freight terminals, and other paved and unpaved areas.

[0119] Figures 5A-5BThese are front views of road markings 445 and 447, respectively, showing radar transceiver 116 transmitting RF signal 1119 and receiving RF signal 1118 as a reflection from road markings 445 and 447. Figure 5A A radar transceiver with road marking 445 is shown, and Figure 5B Another type of road marking 447 with a curved side is shown. Both road markings 445 and 447 contain optical reflectors 275.

[0120] Figures 6B-6D The image shows road marking 284, in which a radar reflector type called a dihedral corner reflector 287 is embedded, as shown. Figure 6A As shown. The dihedral reflectors 287 (and 286) comprise two planar reflectors that intersect along the axis forming the dihedral. This dihedral can be 90° or approximately 90° (i.e., at a right angle, orthogonal, perpendicular, or in a normal direction). Incident waves are reflected parallel to their incident direction and enter an aperture formed with an incident direction perpendicular to the edges (i.e., an incident direction that bisects the 90° angle between the two screens).

[0121] Figure 6B This is a perspective view of road marking 284, on which bifacial reflectors 286 and 287 are located on opposite sides. The bifacial reflectors 286 and 287 can be constructed in various ways. For example, the bifacial reflector 287 can be molded or extruded and cut into segments. The bifacial reflector 287 can be formed, for example, by welding or otherwise joining two strips or plates together, or by bending a flat plate.

[0122] Figure 6B The diagram shows bifacial reflectors 286 and 287 integrated into a road marking 284, which also includes an optical reflector 275 for human observation, a camera, and a lidar sensor. In this embodiment, the bifacial reflectors 286 and 287 are attached to the sides of the road marking 284, and are substantially parallel to the direction of vehicle travel. The methods for attaching the bifacial reflectors 286 and 287 to the central body portion of the road marking 284 may include, for example, gluing, bonding, snap-fit, friction fit, fasteners (e.g., screws, rivets, nails, staples), etc. Optionally, the road marking 284 may have a base plate (not shown).

[0123] A dihedral reflector is a passive device used to reflect radio waves / RF waves directly back towards a transmitting source. Dihedral reflectors 286 and 287 can be right-angled metals, such as aluminum, galvanized steel, copper, brass, magnesium, steel, etc., or any other RF-reflective material. Dihedral reflectors 286 and 287 may also include a metallic or other RF-reflective coating, a metallic or other RF-reflective film, or electroplating of a conductive or other RF-reflective material onto a non-metallic or non-RF-reflective surface such as plastic. The dihedral reflector can also be formed with one side and another side, wherein one side is a road surface (e.g., asphalt, concrete), and the other side is a metallic surface, because a road surface can be sufficiently reflective of RF radiation. For example, when a radar signal comes from the side (right, such as...)... Figure 6A As shown, the radar signal is emitted downwards toward the bifacial reflector 287, and the radar signal is pointed downwards at an angle of less than 45°, for example, 25° (where the horizontal angle toward the horizontal plane is preferably considered 0° and the vertical angle perpendicular to the ground is 90°), and when the radar source is mounted low on the ground, for example, 0.3m, the ground acts as a smooth reflective surface against the RF waves, and the road surface acts as one side against the bifacial reflector. The road surface is more reflective when wet.

[0124] The reflectivity of a road surface can be enhanced by applying an RF reflective adhesive (e.g., conductive epoxy) or an RF reflective coating (e.g., copper, carbon, nickel, and silver conductive coating) to portions of the road path below and / or around pavement markings. For example, MG Chemicals 841AR is an acrylic nickel conductive coating, while MG Chemicals 841ER is a nickel conductive epoxy. RF reflective adhesives can also be used to bond pavement markings (which contain the other surface of a bifacial reflector) to the road surface. Bifacial reflectors can also be formed by coating or covering the relevant side or adjacent side of an existing pavement marking having a vertical or near-vertical side with an RF reflective coating. Bifacial reflectors can also be formed by coating machined grooves, pits, or cuts in the road surface with an RF reflective coating.

[0125] Road marking 284 has optical reflectors 275 similar to those in current road markings to provide optical reflection on the front side facing oncoming vehicles. These optical reflectors in the road marking can be used by a vision camera or a lidar sensor for further redundancy for lateral guidance.

[0126] Figure 6C and 6DTop and side views of road marking 284 are shown. Typical dimensions for current raised road markings installed on roads are typically 100mm × 100mm × 25mm. Using these dimensions, bifacial reflectors 286 and 287 can be approximately 25mm × 25mm × 100mm. These dimensions are for typical current raised road markings; longer or taller raised road markings can be constructed and installed on roads with higher radar cross-sections (RCS).

[0127] Road marking 284 (and other road markings described herein) can be affixed to any driving surface for any vehicle, including roads such as one-way, two-way, or multi-lane roads, highways, main roads, driveways, avenues, tree-lined roads, park roads, trails, country roads, streets, paths, lanes, etc., as well as bridges, tunnels, parking lots, parking structures, loading yards, loading docks, transport stations, loading and unloading areas, warehouse sites, or freight yards, whether paved (e.g., asphalt, concrete, brick, stone) or unpaved. Road marking 284 (and other road markings described herein) is preferably affixed to a surface such that the longitudinal axis of the bifacial reflector within road marking 284 is generally parallel to the direction of vehicle travel and along one or both sides of the vehicle's travel path.

[0128] Figures 7A-7C Examples of road markings shown in 8A-8C are road markings that can be installed below a surface in corrugated road surface, parallel cut grooves, or recesses. Figure 7A A front view of a corrugated pavement 310 is shown, which is a cut groove formed in the road surface 300 to generate an audible sound when a tire drives over it to alert the driver. A radar transceiver 116 transmits a signal 1119 and receives a return signal 1118 from the side of the corrugated pavement 310. In this configuration, the sides and bottom of the corrugated pavement form a bifacial reflector; however, because the road surface material is typically non-metallic, its echo is smaller than that of a metallic bifacial reflector.

[0129] Figure 8A A road marking 394 is shown placed in the corrugated road surface 310. In this embodiment, the returned radar signal 1118 will be altered due to the presence of the road marking 394. The radar return signal characteristics for this arrangement differ from those of an empty corrugated road surface 310.

[0130] Figure 7B A top view is shown of the corrugated pavement 310 along a road with painted lines 910. Figure 8B A top view is shown of a pavement marker 394 installed along a corrugated pavement surface 310 with painted lines 910. Figure 7CA top view of a slot 312 cut out in the road is shown. Here, the radar transceiver 116 observes the slot 312 for a longer period of time, allowing the onboard controller to determine the lateral position and / or vehicle heading based on multiple lateral distance measurements obtained from the long slot 312. Figure 8C Another embodiment is shown in which the pavement marking 394 is installed within the groove 312 where existing pavement markings are installed, preventing snowplows or other equipment from tearing it off the pavement. To improve the reflectivity of these grooves, corrugated pavement strips, or recesses, the processed corrugated pavement strips can be manufactured using a sprayed conductive coating to form a bifacial reflector. Figure 7A A processed corrugated noodle 310 is shown, which includes sides and bottom coated with a conductive paint to increase the reflectivity of the corrugated noodle. (See diagram) Figure 7C The longer, machined road groove 312 shown can be coated with conductive paint along the entire length of the corrugated road surface 312 to provide a larger RCS for radar transceivers to observe.

[0131] Figure 9 A front view of the installed snowplow-type pavement marker 1290 and radar transceiver 116 is shown. The snowplow rides on top of the typically metal sides 1206 and 1208. An optical reflector 1275, typically made of plastic, is mounted in the middle of the frame of the snowplow-type pavement marker 1290, making the marker 1290 visible to the driver or a visual sensor. The radar transceiver 116 transmits a signal 1119 to a metal surface 1285 and receives a signal 1118 returned to the radar transceiver 116 from one side of the pavement marker 1290. The radar return signal 1118 is stronger for the pavement marker 1295 than other raised pavement markers previously described because the pavement marker 1295 is made of metal and some sides are right-angled. The snowplow-type marker 1290 can be installed on the center lane line or inner lane lines so that it can be observed by radar sensors installed in vehicles in two different lanes. The snowplow-type marker 1290 is typically installed on the inner lane lines. When the snow-shoveling marker 1290 is covered by snow, it is invisible to the human eye, cameras, or lidar. However, despite being covered by snow, the marker 1290 is visible to the radar transceiver 116. Concrete barriers, shoulders, streets, road edges and signs

[0132] Figures 10A to 10F Other structures along the roadside are shown. Figure 10A The sidewalk 1422 and the shoulder 1420 adjacent to the road surface 300 are shown. A radar transceiver 116 transmits signal 1119 to the shoulder 1420 and receives signal 1118 from the shoulder 1420. The shoulder 1420 acts as a dihedral reflector, but its reflectivity is lower than that of a metal surface. If the concrete is wet, the reflectivity is even greater.

[0133] Figure 10B Another surface of the concrete shoulder 1424 is shown. In one embodiment, the radar transceiver 116 can change its beam pattern and beam angle to detect distances to the inner shoulder surface. For example, the transmitted signal 1119 is aimed at the bottom of the concrete shoulder 1424, the top of the concrete shoulder 1424, and the center of the concrete shoulder 1424 to obtain optimal reflected return signal 1118.

[0134] Figure 10C A front view of a concrete obstacle 1426 and a radar transceiver 116 is shown. In this embodiment, the radar transceiver 116 can be configured as an angle reflector along the bottom of the concrete obstacle 1426, or as a side reflector along a flat side surface, or both. The radar transceiver can adjust its height and beam angle at 45 degrees relative to the bottom corner of the concrete obstacle 1426, and then change the beam angle to 90 degrees to observe the side surface of the concrete obstacle 1426.

[0135] Figure 10D A road 300 is shown, having road markings 284 on one side and a roadside 305 and off-road surface 1305 on the other side. In this embodiment, a radar transceiver is capable of transmitting a specific beamwidth at a specific angle to detect the roadside. Figure 10E Similar to Figure 10D However, the bottom of the signal pole 1306 can be detected here using a radar transceiver. Figure 10F A perspective view of the center shoulder 1928 and the street-side shoulder 1420 is shown. Radar transceiver 116 (not shown) can receive strong return signals by observing the structure as a corner reflector. Figure 10G A side view of guardrail 1432 is shown, which can be easily detected by radar transceiver 116 if the radar transceiver is roughly directly aimed at the metal guardrail 1432.

[0136] There may be multiple objects or markers with specific radar characteristics along the roadside, which allow the vehicle controller to classify or identify marker-based factors such as returned signal strength, number of markers, and previously recorded data for those markers (e.g., in a database) (e.g., approximate location, distance, expected RCS characteristics, etc.). Utilizing IMU information processing to process radar transceiver signals

[0137] Range-based gating, time-based gating, amplitude-based gating, and other methods (such as Kalman filtering) can be used to ignore reflected signals from objects that are not of interest to the target. Several methods exist for gating or filtering the received signal, which can then be used to detect road markings or other target structures.284 Figure 11A-11C As shown.

[0138] exist Figure 11A The diagram illustrates distance / range gating 3030, which is based on the expected widths of roads and lanes in a database. Lanes are typically 2.7 to 4.6 meters (9 to 15 feet) wide. Vehicles 180 and 182 use radar transceivers 116 and 117 to observe pavement markings and other target structures 284 and 284′ (marked structures) in each lane, but only for the top lane. The recorded data, along with location information (e.g., GPS-based or GNSS-based), can be used to determine the approximate location of the vehicles relative to the street, lane, etc. Using this information, along with the expected lane width or the expected distance to the target structure, a suitable range gating can be determined, such as... Figure 11A As shown in the image.

[0139] exist Figure 11B In this model, the Kalman filter tracks road markings and target structures based on a vehicle lateral movement model, vehicle speed, and expected target structure spacing from a navigation database. Due to the known vehicle model and the Kalman filter, the range gate 3030 can be smaller, thus enabling more filtering of other road debris.

[0140] exist Figure 11C In this context, the time gating 3083 on the expected road marking 284 or other target structure 284′ is based on the vehicle speed and the known spacing of the target structures from the database.

[0141] Figures 12A-12C It shows that the radar transceiver processes and filters both the received signal amplitude (in dB) and the ranging / range of the target to obtain a more reliable distance to the target structure, and that if no marker is visible to the radar transceiver, there is no distance. Figure 12A The diagram shows the distance-time relationship of radar measurements to the strongest target while the vehicle is moving along the road, with clutter from the vehicle to side targets on the side of the road. The side targets include three RF reflective markers 1100, 1102, and 1104. Figure 12B The relationship between radar amplitude and time is shown for the same settings. The three RF reflectivity markers 1100, 1102, and 1104 are as follows: Figure 12BThe highest returned signal strength seen above. The amplitude threshold 1106 can be set to filter radar marker data from clutter. Utilizing both amplitude filtering and range gating, Figure 12C The results show that the radar distances to the three markers 1100, 1102 and 1104 are clearly marked and clutter has been removed.

[0142] These techniques can have static range gating and amplitude thresholds, or the thresholds and ranges can be dynamic (e.g., determined from previously collected radar data). Range, time, and amplitude can be updated with appropriate gating. Ranging / range gating is typically based on road width, lane width, and the number of lanes. Map databases can provide vehicle-based location information using GPS, GNSS, or other navigation sensors. Time gating between road markings can be based on marking spacing and vehicle speed, where time = marking spacing / vehicle speed. Received signal strength (amplitude) gating can be based on the average received signal strength over previous (e.g., the last few) target elapsed periods plus a predetermined threshold.

[0143] Figure 13 This is a block diagram of a lateral guidance system 1850, in which the lateral guidance system can warn the driver using visual, audible, and / or tactile warnings if the vehicle is leaving its lane. If the driver does not take a corrective response, the system 1850 can automatically take measures to keep the vehicle in its lane. This embodiment represents a lane departure warning (LDW), lane keeping assist (LKA / LKS), or lane centering assist (LCA) system. A radar transceiver 116 transmits a signal 1119 in the direction of a side target, such as road markings 284, and receives a signal 1118 reflected from the side target. The distance d between the side target and the radar transceiver 116 is... R The measurements are taken by radar transceiver 116 using known radar technology and provided to the lateral guidance controller 830, such as... Figure 13As shown. In addition to radar input, the guidance controller 830 may also have additional inputs from vehicle speed sensor 8008, steering wheel angle sensor 8028, and IMU 907. Vehicle speed sensor 8008 provides the forward vehicle speed. IMU 907 uses a combination of accelerometers, gyroscopes, and sometimes magnetometers to provide the vehicle's acceleration, angular rate, and sometimes orientation. If vehicle 180 travels too close to or too far from a side target, indicating lane departure, the guidance controller 830 may send an audible signal to speaker 824 (or multiple speakers) to warn the driver of lane departure and / or cause display 826 to visually warn the driver of lane departure and / or cause vibration or other tactile stimulation to the driver. If no driver response is detected, controller 830 may control steering mechanism 802 to control wheels 804 to keep the vehicle within the lane. If turn signal (lights) 822 is activated to indicate a lane change or a turn in the direction of the detected lane departure, guidance controller 830 may not generate an alarm or take action. Figure 13 Another embodiment of the system shown can implement Lane Centering Assist (LCA). The LCA system controls the steering of the vehicle 180 to keep the vehicle in the lane without driver effort, but the system can be overridden by the driver.

[0144] Figures 14-16 IMU 907 is shown, which measures acceleration in the x, y, and z directions, as well as yaw rate, pitch rate, and roll rate. One or more IMU 907s can be mounted on vehicle 180. IMU 907 may also contain a magnetometer for measuring the azimuth of vehicle 180 relative to the Earth's magnetic poles. One IMU 907, mounted near the radar transceiver, measures the yaw rate ψ(dt) and lateral acceleration a of the vehicle's movement. X The IMU 907 also measures the pitch and roll of the vehicle's movement, which are considered for lateral acceleration measurement. When the vehicle 108 passes a side target, the side-looking radar transceiver 116 on the vehicle provides lateral measurements to the side target with a specified RF reflectivity. When the vehicle is not passing a side target (a target with a lower RF reflectivity than specified) or between side targets, the IMU 907 measures the vehicle's lateral acceleration α. X The yaw rate ψ(dt) is used to provide the change in the lateral motion of the vehicle.

[0145] Figure 14 An embodiment using complementary filters to combine radar measurements dx from radar transceiver 116 with the yaw rate from IMU 907 is shown. Figure 14In this configuration, sensor fusion, used to combine sensor data, employs a complementary filter 1908. The yaw rate from the gyroscope in IMU 907 is integrated via integrator 909 to provide the yaw angle and then high-pass filtered via HPF 1157. The radar transceiver 116 has two timing intervals t... R The outputs at the separation point are dx1 and dx2. The two values ​​are subtracted from each other (dx1 - dx2) to form an estimated vehicle deviation angle ψ (radar) representing the path trajectory relative to a side target. The output from this subtraction, divided by the side target distance, is converted into an estimated vehicle deviation angle ψ in degrees and low-pass filtered by a low-pass filter (LPF) 1159. The complementary filter 1908 combines the yaw rate from IMU 907 with the radar-measured deviation angle. The complementary filter 1908 takes a high-frequency update of the heading rate using a low-frequency update of the radar-measured vehicle deviation angle relative to a side target such as road marking 284, and provides a more accurate vehicle deviation angle (i.e., vehicle heading error) as the output of the complementary filter 1908. The complementary filter 1908 has a transfer function of the form shown below: Where ψ(dt) / s is the vehicle deviation angle obtained by integrating the yaw rate, and ψ(radar) is the vehicle deviation angle measured by radar transceiver 116. The integrator block 909 is represented in Laplace format as "1 / s". It has a transfer function G(s) = (K... p * s+K l ) / (s 2 +K p * s+K l The LPF 1159 filters out the yaw angle measured by the radar. A high-pass filter (HPF) 1157 with a transfer function of 1-G(s) filters out the integral yaw rate (ψ(dt) / s). In the complementary filter 1908, the final estimated deviation angle ψ of the vehicle relative to the side target is calculated by adding the low-frequency component measured by the radar transceiver 116 and the high-frequency component from the inertial sensor IMU 907. If the estimated vehicle deviation angle is zero, the vehicle is parallel to the road markings.

[0146] Another embodiment (not shown) uses complementary filters to separate the components from (e.g.) Figure 20 (As shown) The two radar measurements d of the front and rear radar transceivers 116 and 1016 x1 and d x2 And the yaw rate combination from IMU 907. The same complementary filter can be used as... Figure 14 The method shown is used, but two transceivers instead of using the same radar transceiver 116 can be used to provide vehicle heading error.

[0147] Figure 15 This illustrates how the IMU 907 can be combined with radar transceiver 116 using complementary filters within a controller or computer to provide continuous lateral range measurements. The IMU 907 provides rapid updates, while the radar transceiver 116 provides updates as it passes side targets, and combining the two sensors provides continuous or nearly continuous lateral measurements between the vehicle 180 and side targets.

[0148] There is centrifugal acceleration in the curve. Figure 15 The diagram considers this centrifugal acceleration. The centrifugal acceleration in the curve for vehicle 180 is ac = (vehicle speed). 2 / R. The radius of curvature R of the road is equal to the vehicle speed divided by the yaw rate, or R = v / ψ(dt). Centrifugal acceleration a c It equals the vehicle speed multiplied by the yaw rate, or ac = v * ψ(dt). Lateral acceleration a xc Equals the measured lateral acceleration minus the centrifugal acceleration or a xc =a x -a c The lateral distance d from the RF reflective pavement marking at any time X Equal to radar measurement d R Adding the lateral acceleration a during the radar measurement update period xc The change in distance: dx = d0 + v x *Δt+0.5*a xc *(Δt) 2 , where v x From a xc The integral is obtained, and Δt is the time between samples. The radar transceiver measurement d0 takes into account the geometry of the radar transceiver mounting angle and the distance from the ground, and the lateral distance d between the RF reflective road marking 284 and the radar transceiver 116. X This change in lateral range originates from the radar transceiver 116's measurement update of d0 and the distance between side targets, based on measurements in IMU 907. The change in lateral range is based on the integrator unit 909, such as... Figure 15 The lateral acceleration is integrated twice, as shown. The complementary filter uses constants K1, K2, and K3, along with integrator 909, to integrate the radar range d0 with the corrected acceleration a. xc The fusion process is then performed. The IMU 907 also measures the yaw rate angle ψ(dt). Integrating the yaw rate angle yields the change in the vehicle deviation angle λ. In the curve, the vehicle deviation angle λ can change, but the control system results in maintaining a constant or approximately constant distance between the vehicle and road marking 284.

[0149] Figure 16A block diagram of one embodiment is shown, which utilizes a Kalman filter within processor 830 to combine radar transceiver 116 measurements from different roadside targets at approximately the same time with data from other sensors such as vehicle speed sensor 8008, IMU 907, and wheel angle sensor 8028. The inputs to processor 830 are the vehicle's forward speed v from vehicle speed sensor 8008, acceleration and yaw rate ψ(dt) values ​​from IMU 907, wheel angle δ from wheel angle sensor 8028, and radar range measurements from radar transceiver 116. The output of processor 830 is the lateral distance x to a roadside target such as RF reflective pavement markings 284.

[0150] Figures 17A-17B The output of radar transceiver 116 (with and without IMU 907) is shown, measuring the lateral distance from vehicle 180 to a side target such as road marking 284. In this embodiment, the side targets are spaced apart on one side of the road surface. Figure 17A The image shows radar transceiver 116 measuring the distance from vehicle 180 to a side target, or zero when no significant target is passing by. Figure 17B In China, use Figure 15 The complementary filter shown or Figure 16 The Kalman filter shown provides a continuous lateral measurement from the vehicle 180 to a roadside target or a anticipated future target.

[0151] Figures 18-19 Several embodiments of lateral guidance and navigation schemes are shown. Figure 18 This is a block diagram of a guidance / navigation system 850 that warns the driver using visual, auditory, tactile, and / or vibration warnings if the vehicle leaves its lane, and also provides navigation guidance information to the driver. This embodiment embodies a lane departure warning (LDW) and lane keeping assist (LKA / LKS) system integrated with a navigation system that uses radar-based targets to define absolute navigation points. Radar transceiver 116 transmits signal 1119 in the direction of the side target 284 and receives signal 1118 reflected from the target structure 284. The distance between the target structure 284 and radar transceiver 116 is measured by radar transceiver 116 using known radar techniques and provided to the driver as follows: Figure 18 The lateral guidance controller 830 is shown. The radar transceiver 116 measures the distance d from the target structure 284. R The actual lateral distance from the vehicle to road marking 284 differs from the distance d measured by the radar. RThis relates to the geometry of the radar transceiver 116 attached to the vehicle. The range of the radar transceiver 116 can be fused with the GNSS sensor 901, IMU 907, and marker database 8006. The marker database 8006 contains the coordinates (e.g., GNSS) of the location of marker 284 and optionally, the radar characteristics. When the radar transceiver 116 passes marker 284, the radar sensor will know the distance d to marker 284. R The controller 820 is programmed to use current GNSS sensor 901 and IMU 907 information at the current vehicle position and select the most recent marker in database 8006, or acceptablely match the most recent markers of radar features and position information provided by radar transceiver 116 and GNSS sensor 901, respectively. Once a match is found, the navigation information is updated using the precise position information from database 8006. The guidance controller 830 uses, for example, an extended Kalman filter 830 to fuse these sensors (GNSS 901, IMU 907, vehicle speed 8008, and radar 116), such as... Figure 19 As shown. The output of the extended Kalman filter 830 is more accurate position and velocity information under multiple external conditions, such as when navigation / positioning satellites are blocked while in a tunnel. If GPS (e.g., GNSS) satellites are blocked, the IMU sensor 901 can provide relative information about the vehicle's position, and the radar transceiver 116 will provide absolute information whenever the vehicle passes road sign 284.

[0152] By fusing these types of sensors, if a vehicle leaves the lane, Figure 18 The guide controller 830 can provide early warnings. If the vehicle moves too close to or too far from the target 284, indicating lane departure, the guide controller 830 can cause the speaker 824 (or multiple speakers) to sound an audible warning to the driver, cause the display 826 to visually warn the driver of lane departure, and / or cause vibrations in the driver's seat, steering wheel, or other vehicle components. If the turn signal (light) 822 is activated and instructs the driver to initiate a lane change or turn in the direction of the detected lane departure, the guide controller 830 can disable the lane departure warning. Whether the lane departure warning is enabled or disabled by a previous turn signal can be a configurable setting set by the driver, factory, or service technician. The guide controller 830 can also be configured to activate the turn signal indicator (e.g., hazard lights) on the side of the vehicle (corresponding to the detected lane departure) when lane departure is detected. This serves as a warning to other drivers, vehicles, pedestrians, cyclists, etc., that lane departure is occurring or may be imminent (even if the driver has not activated the turn signal). This enhances safety for others compared to situations where no lane change instruction is provided.

[0153] Figure 18 A navigation display 888 is also shown to provide the driver with information about the road the vehicle is traveling on and instructions for following to reach the driver's destination. If the vehicle is leaving its lane, the guidance system 850 can warn the driver using visual, audible, and / or tactile warnings, and if the driver does not take corrective action, the system 850 can automatically take measures to keep the vehicle in its lane. Figure 18 Database 8006 can be upgraded via the Internet 500 to keep database 8006 synchronized and maintained to reflect road changes.

[0154] Figure 19 An embodiment of an extended Kalman filter (EKF) that can be used in a guidance controller 830 to determine guidance information to be provided to the driver is shown. The IMU 907, vehicle speed 8008, radar transceiver 116, GNSS 901, and database 8006 are filtered together using the EKF, which can be incorporated into the guidance controller 830 to provide vehicle position information x and y. Front and rear radars for lateral range and vehicle heading from side targets.

[0155] Figure 20 This is a top-down view showing vehicle 180 traveling along road 300. The dynamics of vehicle 180 show vehicle 180 traveling along the lane at a speed v in the y-direction. The wheel angle δ of the front wheels 804 is shown from the perspective of vehicle 180 traveling straight forward. The x-direction represents the lateral movement of vehicle 180. The yaw angle of vehicle 180 is not zero when traveling around a curve compared to traveling straight forward. Vehicle 180 has a radar transceiver 116 mounted on the side of vehicle 180, which measures the distance d between an RF reflective road marking 284 and the radar transceiver 116. x1 The interval 194 of RF reflective pavement marking 284 is represented by distance d. m Therefore, each time vehicle 180 passes RF reflective pavement marking 284, radar transceiver 116 measures the RF reflective pavement marking 284 that has passed.

[0156] Figure 20 Also shown is another radar transceiver 1016, similar to radar transceiver 116, but mounted on the rear of vehicle 180 (on the same side as radar transceiver 116). Similarly, two radar sensors can be mounted on other sides and measure the distance to RF reflective pavement markings (not shown). Radar transceiver 116 measures the distance d to one of the RF reflective pavement markings 284. x1And at a similar time, or as soon as it passes over RF reflective pavement 284, the radar transceiver 1016 measures the distance d of another of the RF reflective pavement markers 284. x2 In addition to providing the distance from the radar sensor to the RF reflective pavement marking 284, the vehicle heading angle relative to the RF reflective pavement marking can be derived using the following formula: ψ=tan -1 (d x1 -d x2 ) / L) Where d x1 These are radar measurements (values) acquired from radar transceiver 116, where d x2 The radar measurements (values) are acquired from radar transceiver 1016 at approximately the same time, where L is the length between radar transceivers 116 and 1016. The lateral distance d of vehicle 180 can be determined from these two radar distance measurements. x1 And the estimated vehicle heading angle ψ. One embodiment has two radar transceivers, which are spaced at the same interval or at a distance d from multiple road markings 284. m The spacing 194 is such that radar transceiver 116 passes another road marking 284 approximately simultaneously with radar transceiver 1016 passing another road marking 284. This specific radar transceiver spacing L minimizes concerns that vehicle movement might cause problems in measuring the vehicle's heading angle ψ. For example, if the road marking separation distance 194 is 1.5 meters, then the radar transceivers should be spaced apart by 1, 5, 3.0, 4.5, or 6.0 meters so that the two radar transceivers observe the road marking 284 approximately simultaneously.

[0157] The Stanley controller uses the vehicle's heading angle ψ and the position error e(t) at the front of the vehicle (the desired distance minus the radar-measured lateral distance d). x1 This is used to control the steering wheel angle δ. The formula used for the Stanley controller is as follows: δ(t)=ψ(t)+tan -1 (ks e(t) / (ksv+v y (t)) Where δ(t) is the steering wheel angle command at a specific time t, ψ(t) is the vehicle heading angle related to the path trajectory, e(t) is the position error related to the desired path, and v y (t) is the vehicle speed, and ks and ksv are constants that can be adjusted for desired performance. Improvements to the Stanley controller exist, such as preview information, which can provide better performance. These improvements can also be used in the radar transceiver and RF reflective pavement markings described herein.

[0158] Figure 21 This is a top view showing another embodiment of a vehicle 180 traveling along road 300. The dynamics of the vehicle 180 indicate that it is traveling along the lane at a speed v in the y-direction. The wheel angle δ of the front wheels 804 is shown from the perspective of the vehicle 180 traveling straight forward. The x-direction represents the lateral movement of the vehicle 180. When traveling around a curve, the yaw angle of the vehicle 180 is non-zero compared to traveling straight forward. The vehicle 180 has a radar transceiver 116 mounted on the side of the vehicle, which measures the distance d between an RF reflective road marking 284 or a side target and the radar transceiver 116. x2 The spacing of 194 in RF reflective pavement marking 284 is represented as distance d. m And stored in a database for side targets with unequal distances. Each time the radar transceiver 116 passes the mark 284, the radar transceiver 116 measures the RF reflective road mark 284 that has passed. The time t between road marks. R The separation distance d is derived from the set marker 284 stored in the database. m Divide by the average vehicle speed v during the transition between road markings 284:t R =d m / v(average). For example, if vehicle 180 is traveling at a constant speed of 25 m / s and the distance between the markers is 3 m, then the radar transceiver's distance measurement update time t R It is (3m / (25m / s)) or 120ms.

[0159] Figure 21 The forward movement of vehicle 180 from one position to another position 180′, shown in dashed lines, is also illustrated. The same radar sensor 116′ is used in time (t... R Then the lateral distance d of the next road marking 284 will be measured. x1 In addition to providing the distance from the radar sensor to road marking 284, the deviation angle can be derived using the following formula: ψ=sin -1 (d x1 -d x2 / d m ) Where d x2 It is the time t between (road markings) R 、 in d x1 The radar measurements taken prior to the measurement, where d x2 It refers to the radar measurements taken at the current time, and where d m This refers to the spacing of road markings. The lateral distance d of a vehicle at 180 degrees. xThe vehicle deviation angle ψ relative to road marking 284 can be determined from multiple radar distance measurements using multiple road markings 284.

[0160] The distance d between road marking 284 and radar transceivers 116 and 1016 x1 and d x2 Measurements are taken using known radar technology by radar transceivers 116 and 1016 respectively, and provided to the lateral guidance controller 830, such as... Figure 22 As shown. Radar transceivers 116 and 1016, or associated processors (which may be general-purpose processors, signal processors, digital signal processors (DSPs), etc., and whose processing can be implemented using software, hardware, firmware, or a combination thereof), measure the distance d from road marking 284. x1 and d x2 The actual lateral distance from vehicle 180 to road marking 284 is compared with the distance d measured by radar. x1 And related to the mounting geometry of the radar transceiver attached to vehicle 180. The desired control distance d for maintaining vehicle 180 at the center of the lane or at any predetermined distance from road markings 284. C and the distance d measured by radar x1 and d x2 This is the input to the lateral guidance controller 830. In addition to the radar input, the guidance controller 800 also has additional inputs from the vehicle speed sensor 8008 and the IMU 907. The vehicle speed sensor 8008 provides the forward vehicle speed. The IMU 907 uses a combination of accelerometers, gyroscopes, and sometimes magnetometers to provide the vehicle's acceleration, angular rate, and orientation. In this embodiment, the lateral guidance controller 830 receives radar measurements and gyroscope readings to obtain the position error relative to road markings, the vehicle's angular deviation relative to road markings, yaw rate, and vehicle speed. The lateral guidance controller may receive other sensor information, such as lateral acceleration and compass direction, to provide robust lateral guidance control. The lateral guidance controller 800 sends signals to the steering motor or controlled device in the steering mechanism 802. The steering mechanism 802 controls the steering wheels 804. The steering wheels 804 and the steering mechanism 802 are for on-road vehicles, but the vehicle can be an off-road vehicle, and the controller may use hydraulic actuators. The vehicle 180 maintains the desired lateral distance from the reflector road marking 284 by controlling the steering wheel 804. Note that in some cases, only a single steerable wheel may be present, such as on bicycles, tricycles, three-wheeled vehicles, etc.

[0161] Depending on the type of radar technology employed, radar transceivers 116 and 1016 may generate continuous radar transmission signals and / or continuously monitor reflections, or radar transceivers 116 and 1016 may periodically and repeatedly transmit discrete radar signals (e.g., pulses) and monitor reflections. The radar transmission signals are generally partially downward and pointed from the side of vehicle 180, and road markings 284 are designed to partially upward and reflect the incident radar signals back to the side towards the radar signal source (e.g., transceivers 116 and / or 1016) on vehicle 180.

[0162] Radar transceivers 116 and 1016 and / or the lateral guidance controller 830 can filter reflections based on range / distance and / or amplitude to distinguish targets from other objects. Targets (e.g., road markings 284) are typically within a known range of the vehicle. Because the radar cross-section of the bifacial reflector 286 is large for automotive frequencies and because the road markings 284 are within close range of radar transceivers 116 and 1016, the amplitude of the returned signal is typically significantly higher when using bifacial reflector-enhanced road markings compared to the road surface and other road objects such as dead animals, cardboard, rocks, beverage cans, etc.

[0163] Figure 22 This is a block diagram of a lateral guidance system 950 designed to follow lane markings without a driver (i.e., fully automatic steering). Radar transceivers 116 and 1016 are mounted on the sides of vehicle 180, near the front and rear of vehicle 180, respectively. In this example, the side target is a bifacial reflector-enhanced pavement marking 284 mounted on or within a distance of lane markings on road 300. Pavement marking 284 can be a raised pavement marking or mounted at or below the road surface. Radar transceiver 116 transmits a signal 1119 in the direction of pavement marking 284 and receives a signal 1118 reflected back from pavement marking 284 via bifacial reflectors in pavement marking 284. The azimuth of pavement marking 284 is such that its bifacial reflectors are approximately parallel to the lane markings and the direction of vehicle travel. This azimuth provides maximum signal return as radar transceivers 116 and 1016 pass over pavement marking 284.

[0164] In addition to filtering by amplitude and range, other radar processing techniques can be used to distinguish road markings from the road surface and other objects. For example, polarization can distinguish a dihedral reflector from the road surface and other objects on or near the road. Moreover, the fixed or near-fixed intervals of road markings can filter out time-based false signals. For example, reflections arriving between two road markings can be excluded as possible false targets. As mentioned above, Kalman filters, complementary filters, or other known filtering techniques can be used to filter out reflection signals based on fixed spacing / time of road markings and / or other known or predictable contributions of road markings. Road markings 284 can thus be distinguished from other objects, and multiple road markings 284 on the driving surface can be identical or similar to similar dihedral reflectors or similar RCS uniformity.

[0165] Figure 23 This is a block diagram of a lateral guidance control system 970 that controls the steering of a vehicle to keep it within its lane. This embodiment illustrates an autonomous lateral control system. A front radar transceiver 1160 and a rear radar transceiver 1016 transmit signals in the direction of the target and receive signals reflected back from the target. The distance d between the target and radar transceivers 1160 and 1016 is... x1 and d x2 The measurements are taken using well-known radar technology by radar transceivers 1160 and 1016, respectively. The output of radar transceiver 1160, which also has an IMU907 as an input sensor, provides the lateral guidance controller 8004 with the measured distance dx and vehicle deviation angle ψ relative to the target-defined path trajectory. Figure 23 The radar transceiver 1160 (or associated processor) uses inputs from the IMU 907, radar transceiver 1016, vehicle speed 8008, and wheel angle 8020 to calculate the lateral distance d relative to the road markings. x And yaw angle ψ. The desired control distance d from the target. C Distance d measured by radar X The error d is determined by subtracting from it. ERROR This error is the input to the lateral guidance controller 8004. In addition to the distance to the target, the vehicle's deviation angle ψ relative to the target is determined and sent to the lateral guidance controller 8004. Vehicle speed 8008 and road geometry preview information 8006 are also sent to the lateral guidance controller 8004. Other sensors may be present, such as additional IMUs, GPS, vision cameras, lidar, etc. (not shown) that can be used to enhance the lateral control system 970.

[0166] The output of the guide controller 8004 is transmitted via the desired steering wheel command d. CMDThe steering mechanism 8020 controls the wheel angles and, together with vehicle dynamics 8040, controls the lateral position d of the vehicle in the lane relative to the target. XACT The lateral guidance controller system 970 can employ one or more different control algorithms to control the vehicle's steering along road markings. The desired control distance d from the target. C This could be a predetermined distance based on assumptions about lane width, vehicle width, and the location of the radar transceiver on the vehicle. Alternatively, it could be the desired control distance d from the target. C Different lane widths and / or different target locations on different roads can be considered depending on the approximate location of the vehicle. For example, a database can store a set of expected control distances for different roads or geographical locations, and the database can be queried based on the vehicle's geographical location, which is determined, for example, by GPS, sufficient to determine which road or set of adjacent roads the vehicle is traveling on. Furthermore, the expected control distance d from the target... C This can depend on the vehicle's direction of travel, which can be determined from compass sensors and / or GPS measurements, because lane width and / or target location can differ in different directions on the same road. The desired control distance d C Tire wear can be offset from or slightly varied from the actual lane center (e.g., with a small random component) to distribute it more evenly across lanes.

[0167] Figure 24 This is a block diagram of a lateral guidance control system 960, which controls the steering of a vehicle to keep it within its lane. This embodiment represents an autonomous lateral control device. Radar transceivers 116 and 1016, respectively mounted at the front and rear of the vehicle, transmit signals in the direction of a target structure and receive signals reflected back from the target structure. The distance between the target structure and radar transceivers 116 and 1016 is measured by the radar transceivers using known radar technology and provided to the lateral guidance controller 8004, such as... Figure 24 As shown. Radar transceiver 116, mounted on the front of the vehicle, measures the distance dx1 from the target structure. Radar transceiver 1016 measures the distance d from different target structures. X2 The desired control distance d from the target structure C Subtract the distance d measured by radar X1 To determine the cross-track error d ERRORThis information is input into the lateral guidance controller 8004. Vehicle speed 8008, position and radar characteristic database 8006, IMU 907, vision sensor 903, GPS sensor 901, and wheel angle 8028 can be sent to the lateral guidance controller 8004. Additional sensors, such as multiple IMUs, RTK-GPS (Real-time Dynamic Global Positioning System), multiple vision cameras, lidar, etc. (not shown), may be present and used to enhance the lateral control system 960.

[0168] The output of the steering controller 8004 controls the steering mechanism 8020, which controls the wheel angles and, together with vehicle dynamics 8040, controls the lateral position of the vehicle in the lane relative to road markings. Two radar transceivers 116 and 1016 provide the traverse track error d based on forward and backward distance measurements to the markings. ERROR And heading angle error. The lateral guidance controller system 960 can have several different embodiments of control algorithms to control the vehicle's steering along road markings. Some examples are fuzzy control algorithms, proportional-integral-derivative (PID) control algorithms, adaptive PID control algorithms, Stanley control algorithms, model predictive control (MPC) control algorithms, neural network control algorithms, modified sliding mode control algorithms, multi-rate control algorithms, and linear quadratic regulator (LQR) control algorithms.

[0169] The desired control distance d from the target structure c This could be a predetermined distance based on assumptions about lane width, vehicle width, and the location of the radar transceiver on the vehicle. Alternatively, to account for different lane widths and / or the locations of different target structures on different roads, the desired control distance d from the target structure is... C This can depend on the approximate location of the vehicle. For example, the database can store a set of desired control distances for different roads or geographical locations, and the database can be queried based on the vehicle's geographical location, which is determined, for example, by GPS, sufficient to determine which road or set of nearby roads the vehicle is traveling on. Additionally, the desired control distance d from the target structure... C Depending on the vehicle's direction of travel, it can be determined from compass sensors and / or GPS measurements, because lane width and / or target structure location can be the same along different directions on the same road. As mentioned above, the desired control distance d can be offset or changed. C This is to distribute tire wear more evenly on the road.

[0170] In another embodiment, as the vehicle travels along the road, the desired control distance d can be dynamically determined by measuring the distances to the target structures with different lateral offsets. CFor example, lane width can be indirectly measured by: (a) measuring the distance to a target structure marking the boundary of the adjacent lane on a given side of the vehicle; (b) measuring the distance to a target structure marking the boundary of the next lane on the same side of the vehicle; and (c) subtracting those measured distances to calculate the adjacent lane width, assuming that the current lane width of the vehicle is the same.

[0171] If a vehicle is equipped with both right-facing and left-facing radar transceivers, two desired control distances (right and left) can be used, and a control strategy can be employed to balance these two distances (e.g., using the zero difference between the right and left distances as a rated setpoint) to center the vehicle within its lane. Furthermore, the desired control distance d varies depending on the vehicle. c It can be offset or changed from the actual center of the lane so that the tire tread does not wear the road surface in the same area.

[0172] Figures 25 to 27 A top view shows different configurations of distance separation for road markings. Figure 25 This is a top view of a multi-lane highway 3000, with two vehicles 180 and 182 in the highway lanes between painted line 304 and pavement markings 284 and 1284. The separation distance 190 between pavement markings 284 can be constant or variable. The separation distance 190 can be small (e.g., 0.3m or continuous) or large (e.g., 22.4m). Current (conventional) markings are typically spaced approximately 6.1m, 12.2m, or 22.4m on straight roads and gradually curving roads, depending on the road type. Current (conventional) pavement markings are spaced approximately 0.3 to 6.1m around sharp bends. Figure 25 On the straight road shown, road markings 284 can be separated by a constant distance, but offset by half the distance every other lane. Radar transceivers 116, 1016, 117, and 1017 positioned on both sides of vehicle 180 allow the radar transceivers to track road markings 284 and 1284 on both sides, and allow for a larger separation distance 190 between road markings 284 on each side. If, for example, a lateral controller 830 (in...) Figure 22 For good lateral control, a minimum road marking separation of approximately 4m is required. A similar controller performance can be achieved with road markings 284 or 1284 offset by 8m on either side of the lane. Separation distances 190 between road markings, ranging from approximately 0.3m to approximately 8.0m, are well-suited for the lateral controller 830. Figure 22(In the middle), without any enhancement sensors (such as GPS, IMU, cameras, or lidar). A lateral controller with inputs from other sensors (such as GPS and IMU) can achieve good performance with a large separation distance 190 (e.g., about 12.2 meters) similar to currently commonly used road marking intervals. In one embodiment, radar transceivers 116 and 1016 on vehicle 180 see road marking 284 on the right side of vehicle 180. Radar transceiver 117 on the same vehicle 180 sees road marking 1284 in the leftmost lane with radar beam 1107. Therefore, the onboard lateral guidance controller in vehicle 180 can decide to stay in the same road lane and follow road marking 284 on the right side of the vehicle or to make a lane change maneuver and follow road marking 1284 on the leftmost side of vehicle 180. Vehicle 182, with similar radar transceivers 116 and 117, can follow the same strategy. For example, another sensor (not shown) such as radar, vision, ultrasound, or laser, or the same radar transceivers 116, 1016, 117, and 1017 with vehicle detection capabilities (in addition to providing lateral distance) can determine the presence of another vehicle in the left or right lane and allow such lane-changing maneuvers. If the antennas on radar transceivers 116 and 1016 on vehicles 180 and 182 are left-handed polarized and the antennas on radar transceivers 117 and 1017 on all vehicles 180 and 182 are right-handed polarized, then when vehicle 180 passes vehicle 182, the radar signals from radar transceivers 116 and 1016 on vehicle 180 (due to their different polarizations) will not interfere with the radar signals from radar transceivers 117 and 1017 on vehicle 182.

[0173] In another embodiment, Figure 26 The separation distance 194 between road markings 284 is shown to be smaller at curves on road 301, allowing for more radar distance measurements from radar transceivers 116 and 117 to more frequently correct the steering of vehicle 180 to stay centered in the lane. A larger separation distance 192 can be used when on straight sections or exiting curves.

[0174] In another embodiment, Figure 27 The arrangement of pavement markings 285 at the beginning and end of a curve section of road 301 is shown. This arrangement of pavement markings 285 (hereinafter referred to as "coded segments") allows the radar transceiver to pick up additional (preview) information to inform the lateral controller (e.g., in...) Figure 23The controller 8004 in the middle is about to encounter a specific road geometry. For example, after receiving information from the coded segment, the lateral controller can take action to minimize the lateral error when entering and leaving a curve. The coded segment 285 can be used to transmit current or upcoming road geometry (e.g., curve or straight section, narrow lane), intersections, hazards, road conditions, school zones, hospital zones, construction zones, railway crossings, road changes, no-parking zones, speed limits, speed limit changes, or other information. The distance 192 between road markings 284 can be smaller in highway curves 301 to allow more radar distance measurements from radar transceivers 116 and 117 to more frequently correct the steering of vehicle 180 to stay in the center of the lane. A larger separation distance can be used when on a straight section or leaving a curve. Multiple radar sensors for continuous monitoring

[0175] Figure 28 and Figure 29 Another embodiment shown utilizes multiple radar transceivers or multiple transmit / receive antennas of the same radar transceivers 1165 and 1175 attached to the right and left sides of vehicle 180. For example... Figure 28 As shown, as the vehicle 180 moves forward, multiple radar transceivers 1175 on the left side of the vehicle 180 continuously observe road markings 1284. Similarly, multiple radar transceivers 1175 on the left side of the vehicle 180 continuously observe road markings 1284 on the left side or driver's side of the vehicle 180. The spacing between the road markings 1284 is a distance d. m ,like Figure 29 As shown. The array of radar transceivers or antennas 1165 and 1175 covers a distance d on vehicle 180. total If the array spacing d between radar transceivers 1165 and 1175 is... total The distance d between the road markings 284 and 1284 m Compared to the same or larger values, the lateral distance between the vehicle radar and the road markings can be measured continuously or quasi-continuously (discrete measurements can be performed frequently enough to approximate continuous measurements).

[0176] Interferometric Synthetic Aperture Radar (InSAR) and Synthetic Aperture Radar (SAR) are processing techniques that use radar images of a target collected by multiple radar transceivers or multiple receive / transmit antennas to determine lateral range. InSAR and SAR can be applied to road markings and other target structures. Multiple radar images of the same area collected at different times from similar locations as a vehicle passes over a road marking can be compared with each other. The movement of the vehicle toward or away from the road marking can be measured during the time interval between the images.

[0177] Figure 28 The multi-radar / multi-antenna embodiment shown can utilize the same or similar lateral controllers as those that have proven to achieve satisfactory control using continuous marker references along the road. Figure 28 As shown, the alternating intervals of road markings 284 and 1284 change the distance so that road marking 284 on the right is seen by multiple radar transceivers or antennas 1165 for half the time, and road marking 1284 on the left is seen by multiple radar transceivers or antennas 1175 for the other half the time. Through this alternating interval, the number of radars in the radar array is halved. Furthermore, this embodiment shows an IMU 907 mounted at the very center of the vehicle 180. One or more IMUs 907s can be located in different areas of the vehicle 180 or even within multiple radar transceiver arrays 1165 or 1175. The IMU 907 can be combined with radar transceiver arrays 1165 or 1175 to provide lateral distance measurement, as described above. Using the IMU 907, radar transceiver arrays 1165 and 1175 can reduce their length while still providing accurate lateral distance measurement continuously.

[0178] Figure 29 One embodiment is shown in which a radar transceiver array 1175 along one side of the vehicle's entire length observes at a distance d. m The road markings 1284 are spaced apart. Not only can the distances d1 and d2 of the road markings 1284 be measured, but the vehicle heading angle relative to the road markings 1284 can also be calculated based on the two offset (e.g., rear and front) distance measurements.

[0179] Figure 30 A radar transceiver array 4400 with six TX / RX antenna combinations is shown. Each combination consists of a receiving antenna 4306 and a transmitting antenna 4308. The antennas are mounted in array 4302 to form a multi-antenna array for the radar. Additionally, a vehicle speed sensor 8008 and an IMU 907 are included. Other sensors may be added for further redundancy. The vehicle speed can be used in conjunction with the received signal to determine the timing of the transmitted power signal based on the expected transit time of the target by the TX antenna 4308. For example, the IMU 907 may use a Kalman filter or a complementary filter to supplement the radar range measurement. The spacing between adjacent TX / RX combinations is a distance d. ant It can be the width P of the target. W Same length. For example, if the width P of the road marking... W If it is 0.1m, then the distance d ant It can be equal to or less than 0.1m. If the road markings are separated by d m If it is 3.0m, then the total array length d totalIt can be 3.0m or longer. If using... Figure 28 The alternating interval markers shown indicate that the array length d total It will be 1.5m or longer. For an array length of 3.0m, 30 (d) units are required. total / d ant =3.0m / 0.1m)TX / RX combination to provide continuous lateral distance for road markings.

[0180] Figure 31 A schematic diagram of a radar sensor 4500 with multiple transmit / receive antennas is shown. This embodiment can be used with radar transceiver arrays 1165 and / or 1175. Figure 28 The radar processor 4260 activates the frequency synthesizer 4160 to provide a suitable FMCW (Frequency Modulated Continuous Wave) signal, which can be amplified by the power amplifier / phase shifter 4130 and sent to a location set at a distance d. ant Multiple transmit antennas in a paired antenna array with separated spacing. The receive antenna may be part of a paired antenna TX / RX (transmit / receive) combination array 4300 and receives the returned signal, which can be amplified by a low-noise amplifier (LNA) 4150. The received signal is mixed with the transmit signal via a modulator 4180. The signal output from the modulator 4180 is filtered by a filter block 4190 to provide the beat frequency or instantaneous frequency from the modulator 4180. The filtered signal is sampled by an A / D converter 4120 and sent to a radar processor 4260 to calculate the measured distance, velocity, phase, and / or amplitude. Figure 31 Only six TX / RX pairs are shown, but more pairs can be created. If only one pair is set up, more radar transceivers can provide arrays 1165 and / or 1175. The radar processor 4260 controls the power amplifier / phase shifter 4130 to turn on the individual antennas in a time-sequential manner to minimize interference between antenna pairs.

[0181] Figure 32 A schematic diagram of a radar sensor 4510 with multiple transmit / receive antennas is shown. This embodiment can be used with radar transceiver arrays 1165 and / or 1175. Figure 28 The radar processor 4260 activates the frequency synthesizer 4160 to provide a suitable FMCW signal, which can be amplified by the power amplifier / phase shifter 4130 and transmitted to a location at a distance d. antMultiple transmitting antennas are arranged in a paired antenna array spaced apart. However, in this embodiment, a gated power amplifier 4165 is provided for each antenna pair, and the vehicle speed 8088 is provided to the radar processor 4260. The radar processor 4260 can determine which pair of antennas receives distance measurements from road markings 284 or 1284. Once road markings 284 or 1284 are determined relative to which radar antenna pair, the radar processor 4260 can predict when the road marking will be in the next antenna pair based on the vehicle speed 8008, and activate the next gated power amplifier 4165 to transmit and receive signals from that pair. In this embodiment, each antenna pair is activated sequentially to track road markings and measure lateral distance. In other embodiments, other sequences may be used. This minimizes RF interference and reduces the total transmitted power compared to transmitting power simultaneously from all pairs. The time t to the next antenna pair ant It is an antenna pair separation d ant Divide by vehicle speed: t ant =d ant / v. Similarly, as Figure 31 As shown, the receiving antenna may be part of a paired antenna TX / RX (transmit / receive) combination array 4300 and receives the returned signal, which may be amplified by a low-noise amplifier (LNA) 4150. The received signal is mixed with the transmitted signal via a modulator 4180. The signal output of the modulator 4180 is filtered via a filter block 4190 to provide the beat frequency from the modulator 4180. The filtered signal is sampled by an A / D converter 4120 and sent to a radar processor 4260 to calculate the measured range, velocity, phase, and / or amplitude. The radar processor 4260 may control a frequency synthesizer 4160 to activate the individual antennas in a time sequence, thereby minimizing interference between antenna pairs.

[0182] Figure 33 Another embodiment 4600 is shown, which has separate radar transceivers 116 synchronized by a radar controller unit 4360. With this embodiment, currently available off-the-shelf components, such as Texas Instruments' AWR1843AOP, can be used as the radar transceiver 116 and the microcontroller as the radar controller unit 4360.

[0183] Figure 34 It shows the target such as Figure 30 The radar TX / RX antenna array 4400 shown is for, or for, such as Figure 33The diagram shows the output of the radar transceiver array 4600 (the lateral speed of the vehicle from the target vs. the distance of the vehicle traveling along the road), which is given when the target is spaced within the length of the vehicle. The lateral distance between vehicle 180 and the target is shown as constant to illustrate that each TX / RX antenna or radar transceiver will provide the same lateral distance and therefore continuous lateral measurements. in conclusion

[0184] The embodiments, descriptions, and terminology described above are given by way of illustration and example only and are not intended to be limiting. For example, the road markings frequently mentioned in the foregoing description as specific examples of radar-reflective roadside targets are merely illustrative examples. The principles presented herein are equally applicable to other types of side targets, and any other radar-reflective side target can be used instead of road markings in the above examples. The scope of the invention is defined only by the following claims, the claims filed in a continuing application, or the claims filed in a post-grant procedure, and their equivalents.

Claims

1. A device for guiding a land vehicle along a path, wherein one or more side targets are present on the path, the side targets having radar reflectivity characteristics different from the path, the device comprising: A radar sensor, which is mounted to the vehicle and is aimed downward and toward the side of the vehicle, wherein the radar sensor is configured to radiate one or more signals having a main beam pattern center toward the ground and aimed at the side of the vehicle via at least one transmitter toward the path, wherein the radar sensor is further configured to detect one or more reflected signals from one or more side targets along the path via one or more receiving antennas. A processor operatively connected to a radar sensor, wherein the processor is configured to determine the lateral distance between the vehicle and the side target based on reflected signals when the vehicle passes by or first encounters a side target; as well as An inertial measurement unit is configured to determine changes in the lateral position of a vehicle between side targets.

2. The apparatus according to claim 1, wherein, The radar sensor operates in a frequency range from about 300 MHz to about 1 THz.

3. The apparatus according to claim 2, wherein, The radar sensor operates in a frequency range from about 77 GHz to about 81 GHz.

4. The apparatus according to claim 1, wherein, The radar sensor is a frequency-modulated continuous wave radar transceiver.

5. The apparatus according to claim 1, wherein, The radar sensor is an ultra-wideband pulse radar transceiver.

6. The apparatus according to claim 1, wherein, The type of radar sensor is selected from the group consisting of dual-frequency phase difference radar, multi-frequency radar, multi-frequency phase radar, orthogonal frequency division multiplexing radar, frequency shift keying radar, digital code modulation radar, phase modulation continuous wave radar, multiple input multiple output radar, polarized radar, dual polarized radar, monopulse radar, noise radar, and interferometric synthetic aperture radar.

7. The apparatus according to claim 1, wherein, The radar sensor is a monostation type.

8. The apparatus according to claim 1, wherein, The radar sensor is a separate transmitter and receiver unit.

9. The apparatus according to claim 1, wherein, The radar sensor includes an antenna array.

10. The apparatus according to claim 1, wherein, The radar sensor is configured to emit polarized radar signals.

11. The apparatus according to claim 10, wherein, The radar sensor is configured to detect the reflected signal based on its polarization.

12. The apparatus according to claim 1, wherein, The radar sensor is configured to be placed on or inside the front bumper of the vehicle.

13. The apparatus according to claim 1, wherein, The radar sensor is encapsulated within the vehicle's lighting assembly.

14. The apparatus according to claim 1, wherein, The processor is configured to process only a portion of the reflected signal received within a window corresponding to the desired range of the reflecting target.

15. The apparatus according to claim 1, wherein, The processor is configured to perform frequency conversion of the reflected signal.

16. The apparatus according to claim 1, wherein, The side targets are selected from the group consisting of raised road markings, raised road markings with bifacial reflectors, snowplowable road markings, snowplowable road markings with bifacial reflectors, ditches in the path, grooves in the path, road posts, mailboxes, shoulders, concrete obstacles, guardrails, and path edges.

17. The apparatus according to claim 1, wherein, The inertial measurement unit includes an accelerometer that provides lateral acceleration, wherein the lateral acceleration is integrated twice to provide the change in the lateral position of the vehicle between targets.

18. The apparatus according to claim 1, wherein, The inertial measurement unit includes a gyroscope that provides a yaw rate, wherein the yaw rate is integrated once to provide a change in the vehicle's heading, and wherein the change in heading is used to determine a change in the vehicle's lateral position between targets.

19. The apparatus according to claim 1, wherein, The inertial measurement unit includes a magnetometer that provides the orientation of the vehicle, and wherein the orientation is used to determine the change in the lateral position of the vehicle between targets.

20. The apparatus according to claim 1, wherein, The changes in the lateral distance from the radar sensor and the lateral position from the inertial measurement unit are combined via a complementary filter.

21. The apparatus according to claim 1, wherein, The lateral distance from the radar sensor and the lateral position from the inertial measurement unit are combined via a Kalman filter.

22. A vehicle for use on a road, wherein a plurality of side targets are along the road, each side target being characterized by radar reflectivity, the vehicle comprising: First transverse side; A radar transceiver installed on a vehicle, wherein the radar transceiver is characterized by having a central main beam pattern, the center of which is downward and aimed from the side of the vehicle, so that when the vehicle moves forward past a side target on a first lateral side of the vehicle, a reflection is detected from the radar reflectivity of the side target. A processor operatively coupled to a radar transceiver, and the processor is configured to determine the path length from the radar transceiver to a side target based on reflection; as well as An inertial measurement unit is configured to determine the change in the lateral position of a vehicle between side targets.

23. The vehicle according to claim 22, further comprising: The second lateral side, opposite to the first lateral side, The main beam pattern is a first main beam pattern having a first center that is aimed downwards in a first lateral direction from the vehicle, wherein the side target is a first side target on a first lateral side of the vehicle, and the radar transceiver is further characterized by a second main beam pattern having a second center that is aimed downwards in a second lateral direction from the vehicle, such that a reflection is detected from a second radar reflector embedded in the second side target when the vehicle moves past the second side target, wherein the second lateral direction is substantially horizontally opposite to the lateral direction, and wherein the second side target is located on a second lateral side of the vehicle.

24. The vehicle according to claim 22, wherein, The radar transceiver is a first radar transceiver, having a main beam pattern that is downward and aimed from the side of the vehicle. The main beam pattern is a first beam pattern with a first center, the first center being downward and aimed from a first side direction of the vehicle, wherein the side target is a first side target located on a first lateral side of the vehicle. The vehicle also includes: A second radar transceiver is mounted to the vehicle, wherein the second radar transceiver is characterized by a second main beam pattern having a second center that is downward and aimed in a direction from the second side of the vehicle, so that when the vehicle moves forward past a second side target on the first lateral side of the vehicle, a reflection is detected from the radar reflectivity of the second side target.

25. The vehicle according to claim 22, further comprising: An external light assembly, wherein the radar transceiver is located on or inside the external light assembly.

26. The vehicle according to claim 22, further comprising: The front bumper, in which the radar transceiver is located on or inside the front bumper.

27. The vehicle according to claim 22, wherein, The processor is configured to perform or assist in performing one or more of the following functions: lane departure warning, lane keeping, and lane centering assist, based on the path length from the radar transceiver to the side target.

28. The vehicle according to claim 22, further comprising: A lateral positioning system independent of the radar transceiver, wherein the radar transceiver and the processor form a redundant lateral positioning system.

29. The vehicle according to claim 22, wherein, The vehicle is at least partially automated, and the lateral positioning of the vehicle is performed at least in part based on the path length from the radar transceiver to the side target.

30. The vehicle according to claim 22, wherein, The radar transceiver is also configured to perform blind spot detection.

31. The vehicle according to claim 22, wherein, The side targets are selected from the group consisting of raised road markings, raised road markings with bifacial reflectors, snowplowable road markings, snowplowable road markings with bifacial reflectors, road ditches, road troughs, road signs, mailboxes, road shoulders, concrete obstacles, guardrails, and roadsides.

32. A method for determining the lateral position of a land vehicle along a path having side targets having radar reflectivity characteristics different from the path, the side targets being arranged along the path in the vehicle's direction of travel, the method comprising: When a vehicle passes a side target, it transmits radar signals downwards and laterally from the land vehicle toward the side target installed on or near the path. When the vehicle passes a side target, it receives radar reflection signals from the side target at the land vehicle location; The distance between the land vehicle and the side target is determined based on the radar transmitted signal and the radar reflected signal; The change in the lateral position of the vehicle between side targets is determined based on one or more inertial measurements; as well as The approximate lateral position of a vehicle between side targets is determined based on changes in lateral position and the distance between the land vehicle and passing side targets.

33. The method according to claim 32, wherein, For virtually every radar-reflective side target that the vehicle passes through, the steps of transmitting radar signals, receiving radar reflection signals, and determining the distance are repeated.

34. The method according to claim 32, wherein, The launch sequence is repeated periodically at intervals ranging from approximately 0.5 milliseconds to approximately 1 second.

35. The method according to claim 32, wherein, As the vehicle travels along the path, the side targets are distributed along one side of the vehicle.

36. The method according to claim 32, wherein, The path is one lane of a multi-lane road, and the side target is a road marking distributed along a line that divides one side of the path.

37. The method according to claim 32, wherein, The path is one lane of a multi-lane road, and the side target is a road marking distributed along a line that divides the lane adjacent to the lane corresponding to the path of the vehicle.

38. The method of claim 32, further comprising: The radar reflection signal is filtered based on the expected distance between the land vehicle and the side target.

39. The method of claim 32, further comprising: Frequency conversion is performed on the radar reflection signal.

40. The method of claim 32, further comprising: Use distance to guide or assist steering vehicles laterally so they can follow the path.

41. The method of claim 32, further comprising: If the distance exceeds the maximum threshold or is less than the minimum threshold, or if the approximate lateral distance is outside the acceptable range, a warning is issued to the vehicle's driver.

42. The method of claim 41, further comprising: If the distance exceeds the maximum threshold or is less than the minimum threshold, or if the approximate lateral distance is outside the acceptable range, an exterior warning is provided.

43. The method according to claim 42, wherein, External warnings for vehicles include flashing turn signals.

44. The method of claim 32, further comprising: The lane centering assist function and lane keeping function are performed based on the distance between the land vehicle and the side sign.

45. The method according to claim 32, wherein, The vehicle includes a lateral positioning system independent of the method of claim 1, the method further comprising: The distance is used in conjunction with an independent lateral positioning system to improve lateral position determination.

46. ​​The method according to claim 45, wherein, The lateral positioning system includes the Global Navigation Satellite System.

47. The method according to claim 45, wherein, The lateral positioning system includes a visual system for observing the paint lines along the path.

48. The method according to claim 45, wherein, The lateral positioning system includes a lidar system that observes a paint line along the path, a recorded target along the path, or both.

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