Vehicle-mounted ranging system

Disclosed is a vehicle-mounted ranging system having a communication transceiver configured to wirelessly communicate with at least one external communication transceiver and a plurality of ultra-wideband (UWB) transceivers configured to transmit and receive ranging pulses to and from at least one external UWB transceiver associated with the at least one external communication transceiver. A controller is interfaced between the communication transceiver and the plurality of UWB transceivers. The controller is configured to communicate with the associated at least one external communication transceiver to schedule transmission of ranging pulses between the plurality of UWB transceivers and the at least one external UWB transceiver and to calculate ranges between each of the plurality of UWB transceivers and the at least one external UWB transceiver based upon time-of-arrival of ranging pulses transmitted between the plurality of UWB ranging transceivers and the at least one external UWB transceiver.

FIELD OF THE DISCLOSURE

The present disclosure relates to vehicle-to-everything communications and particularly to systems for making ranging measurements and communicating the ranging measurements between vehicles, infrastructures, and persons.

BACKGROUND

The automotive industry continues to adopt new technologies to enhance consumer experiences, safety, and security. Among today's biggest concerns are severe traffic collisions, an area where technology can be applied to save lives. Many efforts are underway to define, develop, standardize, and implement the best technologies to improve road safety. Initially, manufacturers have used stand-alone advanced driver-assistance systems (ADAS) technologies inside vehicles, such as radar and cameras. With these technologies, each manufacturer could implement its own system without the need for standardization.

The next big leap in safety is for vehicles to share information, enabling them to cooperate with each other. This requires standardization to ensure connectivity of vehicles from different manufacturers. Efforts are underway to provide the basis for connected vehicles by standardizing vehicle-to-everything (V2X) connectivity, including vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), and vehicle-to-pedestrian (V2P) protocols. Standardization efforts pertaining to V2X open a way for the adoption of new technologies that enhance the ADAS and connected autonomous vehicle sensor suites. However, other sensors have disadvantages such as multipath echoes and an inability to cooperate in ranging measurements with other vehicles. What is needed is a system that eliminates inaccurate ranging due to multipath echoes while providing ranging cooperation between vehicles.

SUMMARY

Disclosed is a vehicle-mounted ranging system having a controller which utilizes a communication transceiver to wirelessly communicate with at least one external controller over its external communication transceiver. The controller is interfaced between the communication transceiver and the plurality of UWB transceivers. The controller then schedules transmission of ranging pulses between the plurality of UWB transceivers and the at least one external UWB transceiver. The controller also receives data from the plurality of UWB transceivers to calculate ranges between each of the plurality of UWB transceivers and the at least one external UWB transceiver based upon time-of-arrival of ranging pulses transmitted between the plurality of UWB ranging transceivers and the at least one external UWB transceiver. In at least some embodiments, the controller is also configured to set up a secure communication link between the communication transceiver and the at least one external communication transceiver and then to configure the plurality of UWB transceivers with secure scrambling codes for UWB ranging.

DETAILED DESCRIPTION

FIG.1depicts an exemplary embodiment of a vehicle-mounted ranging system10having a communication transceiver12that is configured to wirelessly communicate with external communication transceivers that are mounted to vehicles and infrastructures or are carried by persons such as pedestrians and roadway construction workers. The vehicle-mounted ranging system10further comprises an ultra-wideband (UWB) transceiver14that is configured to transmit and receive ranging pulses to and from external UWB transceivers associated with the external communication transceivers. In the exemplary embodiment ofFIG.1, the vehicle-mounted ranging system10further includes other UWB transceivers14.

The vehicle-mounted ranging system10also includes a controller16that is interfaced between the communication transceiver12and the UWB transceivers14. The controller16is configured to communicate with in-range external communication transceivers to schedule transmission of ranging pulses between the UWB transceivers14and the in-range external UWB transceivers and calculate ranges between each of the UWB transceivers14and the in-range external UWB transceivers14based upon time-of-arrival of ranging pulses transmitted between the UWB ranging transceivers14and the in-range external UWB transceivers14.

In greater detail, the communication transceiver12includes an analog receiver18and an analog transmitter20that are each alternately and selectively coupled to a communication antenna22through a communication antenna switch24. A digital transceiver26is in communication with the analog receiver18and the analog transmitter20. The digital transceiver26is configured to convert analog RF signals received by the analog receiver18into digital receive signals and to generate digitally encoded transmit signals that are converted to analog transmit signals that are transmitted by the analog transmitter20. A phase-locked loop (PLL)/clock generator28generates timing signals for the analog receiver18, the analog transmitter20, and the digital transceiver26.

A state controller30drives the digital transceiver26and the communication switch24between a communication transmit mode and a communication receive mode. In the communication transmit mode, the analog transmit signals are transmitted by the analog transmitter20through the communication switch24to the communication antenna22. In the communication receive mode, RF signals received by the communication antenna22are routed through the communication switch24to the analog receiver18.

A power management block32is configured to provide the digital transceiver26with managed power such as envelope tracking and average power tracking. The power management block32typically receives power from a battery (not shown).

An interface34such as a serial peripheral interface (SPI) is in bidirectional communication with the digital transceiver26. The interface34is also in bidirectional communication with the controller16over a first communication bus36.

Also in greater detail, the UWB transceiver14includes an analog UWB receiver38and an analog UWB transmitter40that are each alternately and selectively coupled to a first UWB antenna42through a first UWB antenna switch44and a second UWB antenna switch46. A UWB digital transceiver48is in communication with the analog UWB receiver38and the analog UWB transmitter40. The UWB digital transceiver48is configured to convert analog RF signals received by the analog UWB receiver38into digital UWB signals and to generate digitally encrypted UWB signals that are converted to analog ranging signals that are transmitted by the analog UWB transmitter40. A phase-locked loop (PLL)/clock generator50generates timing signals for the analog UWB receiver38, the analog UWB transmitter40, and the UWB digital transceiver48.

A state controller52drives the UWB digital transceiver48and the communication switch24between a UWB transmit mode and a UWB receive mode. In the UWB transmit mode, the UWB transmit signals in the form of ranging pulses are transmitted by the analog UWB transmitter40through the first UWB antenna switch44and the second UWB antenna switch46to the first UWB antenna42. In the UWB receive mode, RF signals received by the first UWB antenna42and/or a second UWB antenna54are routed through the second UWB antenna switch46and the first UWB antenna switch44to the analog UWB receiver38.

A power management block56is configured to provide the UWB digital transceiver48with managed power such as envelope tracking and average power tracking. The power management block56typically receives power from a battery (not shown).

An interface58such as a serial peripheral interface (SPI) is in bidirectional communication with the UWB digital transceiver48. The interface58is also in bidirectional communication with the controller16over a second communication bus60.

In greater detail, the controller16includes a processor62and a memory64, which may be a mix of random access memory (RAM) for storing volatile data including processor instructions and read-only memory (ROM) for storing non-volatile data and firmware that includes processor instructions. The processor62is in bidirectional communication with the memory64over a first internal bus66. The controller16further includes a controller interface68such as a SPI. The processor62is in communication with the controller interface68over a second internal bus70. The controller interface68is communicably coupled to both the first communication bus36and the second communication bus60, both of which may be a wired bus or a wireless bus. Examples of suitable wired buses and wireless buses include but are not limited to controller area network (CAN) buses in both hardwired and wireless forms.

The processor62communicates with the UWB transceivers14through the controller interface68and over the second communications bus60. The processor62communicates with the communication transceiver12through the controller interface68and over the first communication bus36. The processor62further communicates through the controller interface68and over the first communications bus36to a navigation control unit72that controls the motion of a vehicle to which the vehicle-mounted ranging system10is mounted. The navigation control unit72may include but is not limited to cameras, radar, lidar, ultrasonic sensors, a steering angle sensor, an odometer, an inertial management unit (IMU), and a global navigation satellite system (GNSS) receiver. The navigation control unit72also typically includes an extended Kalman filter. The navigation control unit72is in communication with vehicle control actuators74over a control bus76that may be a CAN bus.

The memory64may include an encryption generator78that is configured to encrypt communication packets between the communications transceiver12and other communication transceivers associated with other vehicles, pedestrians, and infrastructure elements. The memory64also includes a ranging calculator80that is configured to calculate ranges based upon time-of-arrival of ranging pulses transmitted between UWB transceivers14and UWB transceivers associated with other vehicles, pedestrians, and infrastructure elements. The ranging calculator80may be further configured to calculate ranges based upon angle-of-arrival of ranging pulses transmitted between UWB transceivers14and UWB transceivers associated with other vehicles, pedestrians, and infrastructure elements. In at least some embodiments the UWB transceivers14are configured to encrypt packets that accompany the ranging pulses in order to defeat malicious spoofing attempts.

The memory64further includes a vehicle signaler82that is configured to send signals to the navigation control unit72by way of the processor62, the second internal bus70, the controller interface68, and the first bus36. The signals may include but are not limited to signals to apply brakes, apply the accelerator, steer left and steer right, and apply turn signals left and right. The signals also include values calculated by the processor62that inform the navigation control unit72as to how much braking, acceleration, and steering to apply. In response to the signals generated by the vehicle signaler82, the navigation control unit72drives the vehicle control actuators74to apply the braking, acceleration, and steering. The controller16including the processor62, the encryption generator78, the ranging calculator80, and the vehicle signaler82may be implemented in hardware using logic gates of an application-specific integrated circuit (ASIC). In other embodiments, the controller16including the processor62, the encryption generator78, the ranging calculator80, and the vehicle signaler82may be implemented in the logic gates of a field-programmable gate array (FPGA).

FIG.2depicts a lead vehicle84employing an embodiment of the vehicle-mounted ranging system10followed by a trailing vehicle86that also employs another embodiment of the vehicle-mounted ranging system10. The lead vehicle84and the trailing vehicle86form a platoon of vehicles in the exemplary depiction ofFIG.2. Yet another embodiment of the vehicle-mounted ranging system10is employed on a bicycle88that is depicted adjacent to a passenger side of the lead vehicle84. A pedestrian near the bicycle88is holding a communication device90that may be configured to communicate with communication transceivers12that are associated with the lead vehicle84, the trailing vehicle86, the bicycle88, and infrastructure92such as a traffic light. The infrastructure92may also be, but is not limited to, a stop sign, a yield sign, a speed limit sign, a traffic cone, and roadside kiosk.

The communication device90is shown configured with V2X and UWB functions that are compatible with the communication transceivers12and the UWB transceivers14. The communication device90may be, but is not limited to, a smartphone, a smart watch, or a tablet.

The lead vehicle84has a front-side94, a left-side96laterally spaced from a right-side98, and a backside100coupled to the front-side94by the left-side96and the right-side98, wherein the corresponding antenna42of a first one of the UWB transceivers14is mounted to the lead vehicle84at a first location A that is proximal to both the front-side94and the left-side96, the corresponding antenna42of a second one of the UWB transceivers14is mounted to the lead vehicle84at a second location B that is proximal to the front-side94and the right-side98, the corresponding antenna of a third one of the UWB transceivers14is mounted to the lead vehicle84at a third location C that is proximal to the backside100and the right-side98, and the corresponding antenna of a fourth one of the UWB transceivers14is mounted to the lead vehicle84at a fourth location D that is proximal to the backside100and the left-side96.

The trailing vehicle86has a front-side102, a left-side104laterally spaced from a right-side106, and a backside108coupled to the front-side102by the left-side104and the right-side106, wherein the corresponding antenna42of a first one of the UWB transceivers14is mounted to the trailing vehicle86at a fifth location E that is proximal to both the front-side102and the left-side104, the corresponding antenna42of a second one of the UWB transceivers is mounted to the trailing vehicle86at a sixth location F that is proximal to the front-side102and the right-side106, the corresponding antenna42of a third one of the UWB transceivers is mounted to the trailing vehicle86at a seventh location G that is proximal to the backside108and the right-side106, and the corresponding antenna42of a fourth one of the UWB transceivers14is mounted to the trailing vehicle86at an eighth location H that is proximal to the backside108and the left-side104.

In one exemplary embodiment, the controller16is further configured to use the ranging calculator80to calculate distance between the fourth location D and the sixth location F, and to measure distance between the third location C and the fifth location E when the second vehicle86is following the first vehicle84using ranging pulse time-of-arrival measurements made by the plurality of UWB transceivers14. This crossbar ranging depicted in dot-dashed arrowed lines provides additional accuracy over shortest path ranging depicted in solid arrowed lines. Dashed arrowed lines depict communication paths between communication transceivers12and other V2X transceivers associated with the bicycle88, the pedestrian90, and the infrastructure92. The controller16is also shown simultaneously ranging the bicycle68using the present disclosure's crossbar ranging by calculating distance between location B and location K and calculating distance between location C and location J. The ranging between the pedestrian's communication device90and the second vehicle is depicted being measured between the UWB transceiver14at location L and the UWB transceivers14at locations F and G using ranging pulse time-of-arrival measurements. Ranges between the infrastructure92are shown being measured between the UWB transceiver14at location A, the UWB transceiver14on a topside (e.g., roof) of the first vehicle84, and the infrastructure UWB transceiver at location I. Ranges between the infrastructure92are also shown being measured between the UWB transceiver14at location H, the UWB transceiver14on the roof of the second vehicle86, and the infrastructure UWB transceiver at location I. The ranges may be calculated by the ranging calculator80either by using ranging pulse time-of-arrival measurements or by ranging pulse angle-of-arrival measurements or both. It is to be understood that the UWB transceivers14and/or antennas42may be located on bumpers at the front-sides94,102and the backsides100,108. UWB transceivers14and/or antennas42may also located in door handles and or mirrors of the lead vehicle84and second vehicle86. Moreover, the communication transceivers12and or communications antennas22may be located or co-located with any of the locations of the UWB transceivers14.

FIG.3is a diagram showing the use of an exemplary embodiment of the vehicle mounted ranging system10to assist in lane changing in accordance with the present disclosure. A third vehicle110has a front-side112, a left-side114laterally spaced from a right-side116, and a backside118coupled to the front-side112by the left-side114and the right-side116, wherein the corresponding antenna42of a first one of the UWB transceivers14is mounted to the third vehicle110at a ninth location W that is proximal to both the front-side112and the left-side114, the corresponding antenna42of a second one of the UWB transceivers14is mounted to the third vehicle110at a tenth location X that is proximal to the front-side112and the right-side116, the corresponding antenna of a third one of the UWB transceivers14is mounted to the third vehicle110at an eleventh location Y that is proximal to the backside118and the right-side116, and the corresponding antenna of a fourth one of the UWB transceivers14is mounted to the third vehicle at a twelfth location Z that is proximal to the backside118and the left-side114. In the scenario depicted inFIG.3, the third vehicle110has left a platoon led by the lead vehicle84, and the second vehicle86is in the process of changing lanes to the right in order also to leave the platoon. During this critical phase of breaking up the platoon formation, the lead vehicle84, the second vehicle86, and the third vehicle110are in communication with each other as depicted by dashed arrowed lines between the communication transceivers12, which in this case are labeled V2X.

Additional crossbar ranging is setup between the lead vehicle86and the third vehicle110and between the second vehicle86and the third vehicle110as depicted in the dot-dash arrowed lines. Direct ranging is simultaneously implemented as depicted in solid arrowed lines. The combination of crossbar ranging and direct ranging provides centimeter scale distance ranging during this critical lane changing phase.

In some embodiments, the communication transceivers12may be cellular vehicle-to-everything (C-V2X) communication transceivers that use 5G-PC5 (user equipment-to-user equipment communication over a direct channel) on the 5.9 GHz band as defined by C-V2X specifications and Federal Communications Commission regulations. In other embodiments, the communications transceivers12may be dedicated short-range communication (DSRC) transceivers based on WiFi specifications. The UWB transceiver14may use protocols established in the IEEE 802.15.4a or 802.15.4z, including two-way ranging to multiple UWB transceivers14practically simultaneously.

FIGS.4-7are diagrams showing ranging paths between the lead vehicle84, which is a car and is also labeled C1, and the following vehicle86, which is a car and is also labeled C2. Four of the UWB transceivers14are labeled N1, N2, N3, and N4for each of the lead car C1and the following car C2. The UWB transceivers14labeled N1are located at a driver side of the front-side94,102of each of the lead car C1and the following car C2. The UWB transceivers14labeled N2are located at the left-side96,104of the backside100,108of each of the lead car C1and the following car C2. The UWB transceivers14labeled N3are located at the right-side98,106of the backside100,108of each of the lead car C1and the following car C2. The UWB transceivers14labeled N4are located at the right-side98,106side of the front-side94,102of each of the lead car C1and the following car C2.FIG.4is a diagram showing ranging paths between the lead car C1and the following car C2with first selected UWB transceivers during a first time slot. The first selected UWB transceivers are N3of lead car C1and N1and N4of the following car C2. In this case, UWB transceivers N1and N4of following car C2are receiving ranging pulses from the UWB transceiver N3of the lead car C1.

FIG.5is a diagram showing ranging paths between the two cars C1and C2with second selected UWB transceivers during a second time slot. The second selected UWB transceivers are N2of lead car C1and N1and N4of the following car C2. In this case, UWB transceivers N1and N4of the following car C2are receiving ranging pulses from the UWB transceiver N2of the lead car C1.

FIG.6is a diagram showing ranging paths between the two cars C1and C2with third selected UWB transceivers during a third time slot. The third selected UWB transceivers are N2and N3of lead the car C1and N4of the following car C2. In this case, UWB transceivers N2and N3of lead car C1are receiving ranging pulses from the UWB transceiver N4of the following car following C2.

FIG.7is a diagram showing ranging paths between the two cars C1and C2with fourth selected ultra-wideband transceivers during a fourth time slot. The fourth selected UWB transceivers are N2and N3of the lead car C1and N1of the following car C2. In this case, UWB transceivers N2and N3of the lead car C1are receiving ranging pulses from the UWB transceiver N1of the following car C2.

FIG.8is a diagram generally showing transmit slots setup for ranging between the lead car C1and the following car C2. The transmit time slots correspond directly withFIGS.4through7.

FIG.9is a diagram depicting active transmit slots for active ultra-wideband transceivers transmitting ranging pulses between the backside100of a left-side98of the lead car C1and the front-side102of the left-side106of the following car C2. In this case transmit slot1and transmit slot3are labeled in bold type to indicate that these time slots are used to calculate time-of-flight (TOF) from the lead car1UWB transceiver N3(C1N3) to the following car C2, UWB transceiver N4(C2N4).

FIG.10is a diagram depicting active transmit slots for active ultra-wideband transceivers transmitting ranging pulses in a crossbar fashion between the backside100of the right-side98of the lead car C1and the left-side104of the front-side102of the following car C2. In this case, transmit slot1and transmit slot4are labeled in bold type to indicate that these time slots are used to calculate time-of-flight from the lead car1UWB transceiver N3(C1N3) to the following car C2UWB transceiver N1(C2N1).

FIG.11is a diagram depicting active transmit slots for active ultra-wideband transceivers transmitting ranging pulses between the backside100of the left-side96of the lead car C1and the front-side102of the left-side104of the following car C2. In this case, transmit slot2and transmit slot4are labeled in bold type to indicate that these time slots are used to calculate time-of-flight from lead car1UWB transceiver N2(C1N2) to the following car C2UWB transceiver N1(C2N1).

FIG.12is a diagram depicting active transmit slots for active ultra-wideband transceivers transmitting ranging pulses in the crossbar fashion between the backside100of the left-side96of the lead car C1and the right-side106of the front-side102of the following car C2. In this case, transmit slot2and transmit slot3are labeled in bold type to indicate that these time slots are used to calculate time-of-flight from lead car C1UWB transceiver N2(C1N2) to the following car C2UWB transceiver N4(C2N4).

FIG.13is a diagram depicting timing of the time slots including propagation delays and round robin total time between V2X setup and V2X final. In this case, the round robin total time is an exemplary 1.2 milliseconds.

FIG.14is a diagram depicting an orthogonal signal matrix of a finalize data poll. The letter T written into each cell corresponding to a transmit time slot, car, and UWB transceiver represents a received timestamp.

Overall, the present disclosure provides a combination of a ranging and security by way of the controller16, and the communication transceiver12—which may be a C-V2X communication device or a DSRC communication device, where X is another vehicle, a person, or an infrastructure—and ultra-wideband (UWB) ranging transceivers14to increase the accuracy in an Advanced Driver-Assistance Systems (ADAS) system and autonomous vehicles (AV) that do not utilize drivers. In this disclosure, ADAS and AV are referred to as AAV. The vehicle-mounted ranging system10according to the present disclosure can then have various methods applied to provide different embodiments.

The controller16manages the overall distance calculation system. This may be part of or may be tightly integrated with an AAVsystem. The AAV system uses the C-V2X for various protocols. These protocols set up a communication network between adjacent vehicles traveling on a highway. Once the adjacent vehicles are identified, then the vehicle-mounted ranging system10may be utilized to establish a highly accurate position of adjacent vehicles. The AAV system using a Global Navigation Satellite System may have a general idea of the position of adjacent vehicles but no detailed location of, for example, a front right bumper. The vehicle-mounted ranging system according to the present disclosure provides relatively much faster centimeter relative locations of adjacent vehicles. In other embodiments, the AAV system uses DSRC protocols to set up a communication network between adjacent vehicles traveling on a highway.

Once the AAV establishes the connection with an adjacent vehicle, infrastructure, or person (AVIP), it can request identification information for that AVIP. Using that identification information, this embodiment according to the present disclosure can then communicate with that AVIP.

The controller10can then set up a secure communication link and secure scrambling codes for the UWB ranging algorithms. The controller10can then jointly set up a ranging session to determine the distance to the various sensors on the AVIP. Once the UWB transceivers14gather the time-of-flight information to each of the sensors on the AVIP, they can then calculate the three-dimensional (3D) position of the AVIP, including height and distance. This is critical to accurately project the distance onto a ground plane.

A V2X link uses the communication transceivers12to communicate between vehicles and set up all parameters needed for the UWB transceivers14to start ranging. Once ranging is complete, the V2X link can then be used to communicate the calculated distances to the AVIP. Other information may also be exchanged, such as the location of the various UWB devices on the AVIP. Also, various security protocols can be used to ensure the system is correctly talking with the AVIP and is not being spoofed.

Using relative position calculations over time, the acceleration, deceleration, relative movement left or right can be determined, and safe distances can be maintained or braking/acceleration applied as needed. Uses of the vehicle-mounted ranging system10may include but are not limited to communication from one vehicle to a nearby vehicle to determine the distance between the two and using that distance to calculate the location of different parts of the vehicle to within centimeter accuracy. Other uses of the vehicle-mounted ranging system10may be used to provide assistance in group start from a traffic light, provide indication for emergency braking, provide assisted lane changing, provide assistance in platooning, and provide assistance in entering and exiting a platoon.

Still other uses of the vehicle-mounted ranging system10may include but are not limited to communication from one vehicle to a nearby person to determine the distance between them and then to calculate a centimeter level location of the person. The location of the person is then used to maintain a safe distance between the vehicle and the person by employing the vehicle signaler82(FIG.1) to determine if the vehicle should apply braking and send a braking signal to the navigation control unit72. The vehicle-mounted ranging system10may also be employed to determine the location of the person holding communication device90(FIG.2) to identify a specific target such as for Uber pickup. Moreover, the controller16of the vehicle-mounted ranging system10in at least some embodiments is configured to allow a properly identified person access to the vehicle.

Yet other uses of the vehicle-mounted ranging system10include communication from one vehicle to a nearby infrastructure to determine the distance between them and then using that distance to calculate the location of the infrastructure to within centimeter level accuracy. The controller16is configured to use the calculated location of the infrastructure to maintain a safe distance between the vehicle and the infrastructure. For example, the vehicle signaler82is configured to determine if the vehicle should apply braking and to determine how the vehicle should steer to avoid colliding with the infrastructure.

The vehicle-mounted ranging system10may also be employed to determine the location of a parking spot and to assist in centering in the parking spot. The vehicle-mounted ranging system10may further be employed to determine the location over a wireless charging port or find a kiosk to assist in toll or parking access and payment.

Moreover, the vehicle-mounted ranging system10may also be configured to cooperate with automotive radar, lidar, cameras, and other systems to provide high accuracy location determination. However, the benefits of the UWB transceivers over automotive radar, lidar, cameras, and other systems include the following. The UWB transceivers14measure distance between each other, whereas radar reflects from a surface and then averages to the middle of a surface. With an angled surface, the distance measured by radar is not accurate to a specific point. The UWB transceivers also cooperatively determine when to transmit ranging pulses, thereby reducing the probability of interference. For example, in heavy traffic, with radar devices on each vehicle and each radar device acting independently, communication and ranging interference can occur. Lastly, the UWB transceivers14transmit at least an order of magnitude less power than a comparable automotive radar.

FIG.15is a diagram depicting an exemplary placement of additional UWB transceivers14and/or antennas42adjacent to front-side mounted UWB transceivers.FIG.16is a diagram depicting an exemplary placement of additional UWB transceivers14and/or antennas42mounted at the front and rear quarter panels of the lead car C1and the following car C2. In some embodiments, the antenna42corresponding to each of the plurality of UWB transceivers14is mounted to the lead car C1and the following car C2at locations that provide 180 degree ranging coverage for each of the frontside, the leftside, the rightside, and the backside. In some embodiments, the antenna42corresponding to each of the plurality of UWB transceivers14is mounted to the lead car C1and the following car C2at locations that provide 180 degree ranging coverage for each of the frontside, the leftside, the rightside, and the backside. In some embodiments, each antenna42corresponding to each of the plurality of UWB transceivers14is mounted to the corners of the lead car C1and following car C2to provide 270 degrees of ranging coverage for each of the corners.

FIG.17is a diagram depicting an exemplary placement of UWB transceivers14with antennas42positioned for angle-of-arrival measurements of ranging pulses and additional UWB transceivers14and/or antennas42mounted at doors of the lead car C1and following car C2. In some embodiments, each of the antennas42is mounted to the lead car C1and following car C2at multiple wavelengths from each other to provide ranging pulse reception that is usable by the controller16to calculate angle-of-arrival of the ranging pulses. In at some of these embodiments, the controller16is also configured to calculate distance measurements by either or both time-of-arrival and angle-of arrival.