Navigation infrastructure for motor vehicles

A transit system includes a road, a plurality of pavement markers spaced apart along a lane line of the road, and a plurality of RF devices carried by the pavement markers. The RF devices are configured to transmit RF navigation signals to motor vehicles traveling along the road.

BACKGROUND

A self-driving vehicle is capable of controlling steering, acceleration, and braking without direct driver input. The input is provided by sensors such as radar, lidar, GPS, odometry, and computer vision.

However, GPS and computer vision have certain drawbacks. Thick fog, smoky conditions, and snow may make it difficult for the computer vision to generate an accurate view of roads and other surroundings. As for GPS, it has accuracy problems for moving vehicles (especially at high speeds) and vehicles in certain locations (e.g., downtown cities, and canyons). In addition, GPS is vulnerable to “spoofing” attacks, which generate false GPS signals. Spoofing attacks can create security and safety issues for self-driving vehicles.

DETAILED DESCRIPTION

Reference is made toFIG.1, which illustrates a transit system110for motor vehicles100. The transit system110includes a road120, and a plurality of pavement markers130spaced apart along the road120. The pavement markers130may be raised, recessed, or embedded in the road120(or any combination thereof). Examples of the pavement markers130include, without limitation, Bott's dots, raised pavement reflectors, cats eyes, and delineators. The pavement markers130may form lane lines131,132and133, which define lanes121and122of the road120.

A plurality of RFID devices140are carried by the pavement markers130. The RFID devices140are also spaced apart along the road120. The RFID devices140are configured to generate and transmit RFID navigation signals150to motor vehicles100traveling down the road120.

As a motor vehicle100approaches or reaches a pavement marker130, it receives an RFID navigation signal150from the RFID device140carried by that pavement marker130. The motor vehicle100may process that RFID navigation signal150to determine a lateral lane position of the motor vehicle100. For instance, the motor vehicle100may use strength of signal (“SoS”) or time of flight (“ToF”) of the RFID navigation signal150to determine a lateral distance (d1) to a lane line131. If pavement markers130are on opposite sides of the motor vehicle100(as illustrated in the example ofFIG.1) and the motor vehicle100receives RFID navigational signals150from its opposite sides, the motor vehicle100may use a differential ToF or a differential SoS to determine the lateral distance (d1-d2) of the motor vehicle100from the centerline of its lane121.

As the motor vehicle100continues down the road120, it receives additional RFID navigation signals150and computes a sequence of lateral lane positions. A motor vehicle100that is partially or fully automated may use these lateral lane positions to make accurate real time adjustments to the steering of the motor vehicle100. A vehicle100that is not automated may use these lateral lane positions to alert the driver that the motor vehicle100is drifting.

At least some of the RFID navigation signals150may also be encoded with road information. The encoded road information may include the position of a pavement marker130from the center of its associated lane, which enables the distance from the centerline to be determined from only the lateral distance d1. This is beneficial for lanes that are uneven or non-parallel.

The encoded road information may describe a lane border (which can identify the lane in which the motor vehicle100is located), indicate the nearest exit and distance to the nearest exit, and provide GPS information about the location of its corresponding pavement marker130. If the motor vehicle100receives RFID navigation signals150from opposite sides of a lane, the motor vehicle100may use the GPS positions of the pavement markers130to calculate the center lane position.

The encoded road information may further include upcoming traffic information such as distances to stop signs, traffic lights, and intersections. The encoded road information may include road topography, such as distance to changes in road curvatures and grades (e.g., the number of feet to the start of a turn with a curvature of a given radius; and the number of feet to the start of downgrade of a certain percentage). Traffic information such as road topography enables the motor vehicle100to know what is coming ahead, and plan for turns and other maneuvers.

Different classes of autonomous vehicles may use the RFID navigation signals150in different ways. In the United States, the National Highway Traffic Safety Administration (NHTSA) has proposed a formal classification system that involves five levels.

A motor vehicle100having a level 0 classification has no automation, but it may issue warnings. For instance, such a motor vehicle100may include a processor that processes a sequence of RFID navigation signals150to determine whether the motor vehicle100is drifting in its lane, and that sounds an audible alarm when drifting occurs (unless a turn signal is activated or the motor vehicle100otherwise indicates that it is changing lanes). The encoded road information may be used by a navigation system aboard the motor vehicle100(e.g., a built-in navigation system, or a mobile application such as Google Maps Navigation).

A motor vehicle100having a level 1 classification has function-specific automation. That is, one or more specific control functions are automated. Examples include electronic stability control or pre-charged brakes, where the motor vehicle100automatically assists with braking to enable the driver to regain control of the motor vehicle100or stop faster than possible by acting alone. A motor vehicle100having a level 1 classification may utilize the RFID navigations signals150in the same manner as a motor vehicle100having a level 0 classification.

A motor vehicle100having a level 2 classification has combined function automation. At least two primary control functions are designed to work in unison to relieve the driver of control of those functions. An example is adaptive cruise control in combination with lane centering. A motor vehicle100having a level 3 classification has limited self-driving automation. In such a motor vehicle100, a driver can fully cede control of all safety-critical functions in certain conditions. Such a motor vehicle100can sense when conditions require the driver to retake control and can provide a “sufficiently comfortable transition time” for the driver to do so. For instance, the steering is performed by the vehicle's control until the driver retakes control.

A motor vehicle100having a level 2 classification or a level 3 classification may utilize the RFID navigational signals150to determine lateral lane positions and use the lateral lane positions to adjust steering in real time to maintain the position of the motor vehicle100in its lane. Even if the lane lines are obscured by snow, fog, or other environmental factors, the vehicle position may be maintained without ceding control to the driver.

A motor vehicle100having a level 3 classification may use the road information encoded in the RFID navigation signals150to set longer warning times when encountering road situations where the motor vehicle100needs to cede control to the driver. For instance, if the encoded road information indicates upcoming road work and lane closures, or sharp turns in the road ahead, the motor vehicle100can warn the driver that it will cede control in a comfortable time period, rather than ceding in an urgent manner when it encounters road conditions that it is unable to navigate safely.

A motor vehicle100having a level 4 classification has full self-driving automation. Destination or navigation input is provided at the beginning of a trip, but a driver is not expected to be available for control at any time during the trip. Thus, such a motor vehicle100may be driverless, and it may be occupied or unoccupied. A motor vehicle having a level 4 classification may utilize the RFID navigations signals150in the same manner as a vehicle having a level 3 classification, except that control is not ceded at any time to a driver. Thus, a motor vehicle100having a level 4 classification can use the RFID navigational signals150to maintain vehicle lane position, and it can use the encoded road information to plan for upcoming turns (e.g., reducing speed for an upcoming sharp turn), exits, lane changes, and other driving maneuvers, and plot a driving path.

The RFID devices140may be passive, active or any combination thereof. Active RFID devices140include their own power source, or they draw power from a power source carried by its corresponding pavement marker130. For instance, the pavement marker130may carry a battery, or it may carry solar cells.

Active RFID devices140may periodically generate RFID navigation signals150. They may also have a greater transmit range than passive RFID devices140. Range of the RFID navigation signals150is typically a function of such factors as transmit power, receive sensitivity and efficiency, antenna, frequency, device orientation, and surroundings.

Passive RFID devices140harvest power from interrogator signals to generate and transmit the RFID navigation signals150. (As used herein, passive RFID devices140include semi-passive devices, which also harvest power from the interrogator signals.) The range, strength and frequency of the interrogator signals may depend in part upon speed of the motor vehicle100and distance (along a lane) between pavement markers130. The interrogator signals may be transmitted in a forward direction. For the transit system110ofFIG.1, as a motor vehicle100traveling along the road120may broadcast interrogator signals in a forward direction. An RFID device140ahead of the motor vehicle100receives an interrogator signal and responds by transmitting an RFID navigation signal150. The motor vehicle100receives the navigation signal150as it approaches or reaches the RFID device140.

At any given time, the motor vehicle100may receive RFID navigation signals150from more than one RFID device140. As mentioned above, the motor vehicle100may receive RFID navigation signals150on opposite sides. The motor vehicle100may receive RFID navigation signals150from an adjacent pavement marker130and at least one pavement marker130further up the road120.

There is no need for each pavement marker130to carry an RFID device140. If pavement markers130are clustered together, only one or a few of the pavement markers130in the cluster may carry an RFID device140. Even if the pavement markers130are not clustered, every nthpavement marker130along a lane may carry an RFID device140(where integer n>1).

The example ofFIG.1shows a road120having two lanes121and122, two outer lane lines131and132of pavement markers130, and a middle lane line133of pavement markers130. However, the transit system110is not so limited. Other roads120may have different numbers of lanes and lane lines. For instance, a road120might have a single lane and a single line of pavement markers130.

More than one RFID device140may be carried by a pavement marker130. For instance, the pavement markers130forming the middle lane line133may carry two RFID devices140: one for transmitting an RFID navigation signal150into the left lane121, and the other for transmitting an RFID navigation signal150into the right lane122(in contrast, each of the pavement markers130forming the outer lane lines131and132may carry only a single RFID device140). The RFID device140may direct their RFID navigation signals150at an angle that maximizes the signal from the desired lane, and minimizes the signal from the undesired lane.

The transit system110is not limited to pavement markers130. A pavement marker130is but one type of roadside marker. Other types of roadside markers may be used instead of, or in addition to, the pavement markers130. For instance, the RFID devices140may be carried by roadside markers such as guard rails and k-rails.

FIGS.2A to2Fillustrate three different examples210,220and230of an apparatus including a pavement marker130and at least one embedded RFID device140. In each example210,220and230, the pavement marker130is a Bott's dot. A typical Bott's dot is semi-hemispherical. A flat surface of the Bott's dot is secured to the road120. At least one RFID device140is embedded within the Bott's dot. For illustrative purposes,FIGS.2A-2Fshow the Bott's dots as being made of translucent material, whereby the RFID devices140are visible. In practice, however, the Bott's dots are typically made of ceramic or plastic. RF signals penetrate both ceramic and plastic in the length scales of Bott's dots.

Orientation of the RFID device140within the Bott's dot may be characterized by a mounting angle. The RFID device may be oriented parallel to (facing) the flat surface of the Bott's dot (mounting angle=0 degrees), it may be oriented perpendicular (edge-wise) to the flat surface (mounting angle=90 degrees), or it may be oriented at some mounting angle between 0 and 90 degrees.

The pavement marker130may have markings to allow it to be installed at a known orientation with respect to the lane line. In this known orientation, the RFID navigation signal150is transmitted perpendicular to the lane line and across the road (as illustrated inFIG.1). The RFID navigation signal150is received as the motor vehicle100reaches the pavement marker130. At this orientation, the RFID device140is said to have a transmission angle of 0 degrees. At a non-zero transmission angle, the RFID navigation signal150is directed towards the motor vehicle100as the motor vehicle100is approaching (but has not yet reached) the pavement marker130.

FIGS.2A and2Billustrate top and side views, respectively, of the first example210. The RFID device140is oriented at a mounting angle of 90 degrees, and its transmission angle is roughly 0 degrees.

FIGS.2C and2Dillustrate top and side views, respectively, of the second example220. The RFID device140is oriented at a mounting angle of 0 degrees, and the transmission angle is roughly 0 degrees.

FIGS.2E and2Fshow top and side views, respectively, of the third example230, in which the Bott's dot carries a first RFID device140ahaving a short transmission range, and a second RFID device140bhaving a long transmission range. The first RFID device140adirects its RFID navigation signal150aat a transmission angle of zero degrees, and the second RFID device directs its navigation signal150bat a non-zero transmission angle (α). The navigation signal150atransmitted by the first RFID device140ais received by motor vehicles100close to the pavement marker130and are used primarily to determine the lateral lane position. The RFID navigation signal150transmitted by the second RFID device140bis received by motor vehicles100further away and are used primarily to provide encoded road information.

In North America, the first RFID device140amay transmit at, for example, 902-928 MHz UHF ISM band, which can be adjusted to cover about 1 to 12 meters; and the second RFID device140bmay transmit at 433 MHz, which can be adjusted to cover about 1 to 100 meters. In Europe, the first RFID device140amay transmit at 865-868 MHz UHF ISM band, and the second RFID device140bmay transmit at 433 MHz.

FIGS.3A to3Eillustrate three additional examples310,320and330of an apparatus including a pavement marker130and at least one embedded RFID device140. In each additional example310,320and330, the pavement marker130is a raised pavement reflector. The raised pavement reflector includes a reflector body302that is shown as being made of a translucent material (for illustrative purposes), but is typically made of plastic or ceramic. A bottom planar surface304of the reflector body302is secured to the road. The reflector body302also has angled surfaces305and an upper planar surface306. The angled surfaces305of the reflector body302may be coated with reflective material, or reflectors may be epoxied to the angled surfaces305. The raised pavement reflector may also include a lens or sheeting that covers the angled surfaces305. The lens or sheeting enhances visibility by reflecting automotive headlights. At least one RFID device140may be mounted beneath the angled and upper surfaces305and306. If reflectors are epoxied to the reflector body302, an RFID device140may instead be embedded in the epoxy.

FIGS.3A and3Billustrate top and side views, respectively, of the first additional example310. The RFID device140is mounted underneath the upper planar surface306at a mounting angle of roughly 0 degrees (roughly parallel to the upper planar surface306). The position of the RFID device140shown inFIGS.3A and3Bis not limiting. The RFID device140may be mounted at another mounting angle and may be positioned at another distance from within the reflector body302.

FIGS.3C and3Dillustrate top and side views, respectively, of the second additional example320. The RFID device140is surface mounted underneath one of the angled surface305of the reflector body302. Mounting angle is between 0 and 90 degrees.

The raised pavement reflector may have a rectangular geometry, but it is not so limited. For instance, corners of the raised pavement reflector may be cut on the corners facing oncoming motor vehicles100.

FIG.3Eillustrates a top view of the third additional example330, in which the reflector body302is cut on corners332facing oncoming motor vehicles100. An RFID device140is mounted underneath each cut corner332The RFID devices140are oriented to face adjacent lanes. This creates a higher signal to and from the antenna.

Another example of a pavement marker130(not illustrated) is a “cat's eye,” which may include two pairs of reflective glass spheres set into a flexible white rubber dome, mounted in a metal housing. The rubber dome may be occasionally deformed by passing traffic. One or more RFID devices140may be embedded in the spheres or attached to the metal housing.

Another example of a pavement marker130(not illustrated) is a “delineator.” A delineator is a tall pylon (similar to a traffic cone or bollards) mounted on a road surface, or along an edge of a road. Delineators are typically used to channelize traffic. One or more RFID devices140may be attached to the pylon.

The RFID devices140may be embedded in or mounted to the pavement markers130at the time of manufacture of the pavement markers130. However, pavement markers130already on a road may be retrofitted to include the RFID devices140. A pavement marker130may be retrofitted, for instance, by boring a small hole, embedding the RFID device140in the hole, and either filling the hole with epoxy or covering the hole with tar or another material.

As mentioned above, the RFID devices140may be carried by roadside markers such as guard rails and k-rails. The RFID devices140may be attached to the surface of k-rails or embedded in the k-rail material at the time of manufacture. The RFID devices140may be mounted on housings on the posts of the guard rails, or on another surface. The RFID devices140may be embedded in the posts, for example, by boring holes in the posts and inserting the RFID devices140, with or without device housings.

Reference is made toFIG.4, which illustrates functional components of a passive RFID device140including a processor410, machine-readable memory420, transceiver430, and antenna440. Road information422may be stored in the memory420. The transceiver430receives an interrogator signal, which powers the processor410to generate an RFID navigation signal (including encoded road information), and send the RFID navigation signal to the transceiver430. The transceiver430then transmits the RFID navigation signal via the antenna440. A directional antenna440is preferred, but the antenna440may be isotropic. Consider the RFID devices140along the middle lane line133inFIG.1. They made include two directional antennae or a single isotropic antenna.

The RFID devices140may be configured to receive messages or data from RFID printers, and store information contained in those messages or data. For instance, if any exit is closed due to maintenance, this exit closure information may be wirelessly downloaded or printed to the RFID devices in those pavement markers130preceding the closed exit.

GPS location may also be printed in the memory420of the RFID device140. By printing the GPS location on the RFID device140, spoofing can be thwarted because the RFID information is local, and redundant. If a GPS satellite signal is jammed and emulated with false information, the observed GPS satellite information will not agree with the printed GPS information.

Reference is now made toFIG.5, which illustrates a motor vehicle500. Examples of the motor vehicle500include, but are not limited to, an automobile, motorcycle, utility vehicle, truck, and transport vehicle (e.g., bus, passenger van).

The motor vehicle500includes a body510, data sensors520, at least one RFID reader530, and a vehicle control540. (Other elements of the motor vehicle500, including the engine and drive train, are not illustrated.) In the case of a motorcycle, the body510includes a frame. In the case of an automobile, the body510includes a chassis and an outer shell attached to a chassis.

The vehicle control540may be automated (resulting in an NHTSA classification of 1 or greater), or it may not be automated (resulting in an NHTSA classification of 0). A vehicle having a level 4 classification may be driverless.

The data sensors520generate sensory data for the motor vehicle control540. Examples of the data sensors520include, but are not limited to, radar, lidar, GPS, odometry, and computer vision. The vehicle control540may use this sensory data for various functions including, but not limited to, distinguishing between different cars on the road, identifying signs, planning appropriate navigation paths, and collision avoidance.

The RFID reader530includes an antenna532mounted to the body510at a location for capturing the RFID navigation signals during movement of the motor vehicle500. The RFID reader530further includes an RFID receiver534for processing the captured RFID navigation signals to determine a lateral lane position of the motor vehicle500during movement of the motor vehicle500. The RFID receiver534may also extract encoded road information from the captured RFID navigation signals.

The RFID reader530may be active or passive. If the RFID devices are active, the RFID reader530may be passive or active. If the RFID devices are passive, then the RFID reader530may be active. The vehicle500may supply power to an RFID reader530that is active. An RFID reader530that is active may also have a transmitter536for transmitting interrogator signals via the antenna532during movement of the motor vehicle500.

The RFID reader530ofFIG.5is illustrated in terms of functionality. The receiver534and the transmitter536may be integrated into a single transceiver, or they may be implemented as separate components. The receiver534and the transmitter536may have separate processing capability, or they may share a common processor. The RFID reader530may contain more than one receiver and one transmitter, which may operate at the same or different frequencies.

Additional reference is made toFIG.6, which illustrates a method in which the motor vehicle500is controlled to move along a road marked with roadside markers. At least some of the roadside markers carry active RFID devices140and/or passive RFID devices that broadcast RFID navigation signals when interrogated.

At block610, as the motor vehicle500moves along the road in a forward direction, it broadcasts interrogator signals and it receives RFID navigation signals transmitted by the interrogated RFID devices140. The interrogator signal may be broadcast continuously or in timed radio pulses.

At block620, the RFID receiver534processes the RFID navigation signals to determine lateral lane position of the motor vehicle500. If the RFID navigation signals are received from only one side of a lane, absolute distance from a lane line may be determined. If the RFID navigation signals are received from opposite sides of a lane, a differential signal can be used to determine the distance from the lane's centerline.

The processing of the RFID navigation signals may also include measures to prevent false information or interference from other vehicles on the road. For instance, the motor vehicle100has an identifier and/or identifying handshaking signal (e.g., a series of short or long pulses), which are reflected by the roadside markers. Thus, the RFID reader530only listens to the navigation signal returned in response to the handshaking signal.

At block630, the RFID receiver534may also extract any encoded road information from the RFID navigation signals.

At block640, the vehicle control540uses sensory data from the data sensors520and the lateral lane position from the RFID reader530to control the motor vehicle500. For example, an automated vehicle control540can use the lateral lane position to steer the motor vehicle500(e.g., center the motor vehicle500in a lane), and it can use the road information to plan for upcoming maneuvers and plot a driving path. The vehicle control540can use information such as identification of next exit, and distance to next exit, to safely execute lane changes to position the motor vehicle500to take the exit when it approaches the exit. It can use information such as lane closures to navigate the motor vehicle500to lanes that are open to traffic.

In some instances, the RFID reader530may determine optimal frequency or period of interrogation as a function of distance between pavement markers and speed of the motor vehicle500. The distance may be known in advance, or the distance may be determined in real time (e.g., from the time of flight or GPS location information broadcast from the roadside markers). If the roadside markers are x feet apart, and the motor vehicle500is moving at a speed of y feet per second, then the interrogation signal may be broadcast at an optimal period of once per x/y seconds. If the distance is not known in advance, the interrogation signals may be broadcast at a high frequency to determine the position of the highest signal detected from the roadside markers, and then adjust the interrogation frequency to the optimal frequency.

The motor vehicle500may have one or more of the RFID readers530for generating the interrogation signals and capturing the RFID navigation signals. Interrogation by multiple RFID readers530delivers more power to passive RFID devices. Interrogation by multiple RFID readers530also allows greater control of the angle of the interrogation signal relative to the roadside markers. Whereas a single RFID reader530at the front center of the motor vehicle500is positioned forward to interrogate both sides of the lane, RFID readers530on opposite sides of the motor vehicle500may be angled to see the roadside markers coming ahead and can anticipate locations and changes in lane curvature.

FIGS.7and8illustrate different configurations of the motor vehicle500. In the configuration ofFIG.7, an RFID reader530is mounted to the front center of the motor vehicle500, and two other RFID readers530are mounted on the opposite sides of the motor vehicle500(e.g., in wheel wells of the motor vehicle500). In the configuration ofFIG.8, two RFID readers530are mounted to the front of the motor vehicle500, and two other RFID readers530are mounted on the opposite sides of the motor vehicle500. These configurations enable multiple interrogations in a forward direction.

In the configuration ofFIG.8, the RFID readers530do not process the received RFID signals. Instead, the RFID readers530are electrically connected to a shared processor810, which performs the processing. The shared processor810may or may not share other vehicle functions such as steering, braking, navigation calculation, GPS positioning, etc.

The motor vehicle500is not limited to the configurations illustrated inFIGS.7and8. In another configuration, the motor vehicle500may have only a single RFID reader530located at the front. In yet another configuration, the motor vehicle500may have only RFID readers530on opposite sides. In still another configuration, the motor vehicle500may have one or more RFID readers530mounted at the back of the motor vehicle500. Other configurations may have additional RFID readers530at strategic locations for better signal reception.

In other configurations of the motor vehicle500, the RFID readers530may be placed at other positions from which they can interrogate and receive the RFID navigation signals from the RFID devices in the roadside markers. For instance, there may be ports intentionally designed into the body510of the motor vehicle500for the express purpose of mounting the RFID readers530.

Thus disclosed is an infrastructure that can immediately provide local position information to autonomous motor vehicles. The infrastructure utilizes existing roadside markers, with only minor modifications to those roadside markers. It does not depend upon uniform width of the roads.

The infrastructure provides advantages over computer vision and GPS. The RFID environment is better suited than GPS for detecting lateral lane position of fast-moving vehicles. It is better suited than computer vision for detecting lateral lane position in inclement weather and other conditions (e.g., snow, sand, smoke, thick fog, white out conditions) that obscure lane lines and other road details. Thus, the infrastructure creates much greater safety for autonomous vehicles in both normal and difficult conditions.

A transit system herein is not limited to standard RFID devices140. RFID devices140that differ from the standard may be used. For instance, the non-standard RFID device operates similar to a standard RFID device, but may communicate over non-standard radio frequencies (e.g., special frequencies slotted for autonomous navigation). In this case the first and second RFID devices140aand140bmay broadcast at frequencies to be reserved by the International Organization for Standardization for navigational systems. The RFID devices140may have different nomenclature. Other aspects of the standard RFID device may be altered including, but not limited to, range, memory size, and memory configurations.

A transit system herein is not even limited to RFID devices140. The RFID devices140described herein are but one type of RF device. The roadside markers may carry other types of RF devices instead of, or in addition to, RFID devices140. These other types of RF devices include, but are not limited to, WiFi devices, Bluetooth devices, and ZigBee® devices.

The RF devices generate and transmit RF navigation signals. The RFID navigation signal150is a type of signal generated and transmitted by RFID devices140.