The present specification relates to systems and methods for controlling a vehicle and, more particularly, to systems and methods for controlling a vehicle with respect to a dilemma zone or an option zone at an intersection.
Drivers of vehicles, as well as autonomous vehicles, may encounter a dilemma zone or an option zone near an intersection with a traffic light. Traffic lights cycle through several states to control the flow of vehicles through an intersection. For example a traffic light may have a green light that is illuminated for a first period of time, a yellow light that is illuminated for a second period of time and a red light that is illuminated for a third period of time. The green, yellow and red lights cycle through the sequence sequentially.
An option zone is an area of the road before a stop line of an intersection where a traffic light is yellow and a driver could drive through the intersection before the traffic light turns red or stop at the stop line. However, the driver may be indecisive and hesitate to stop the vehicle or driver through the intersection because he or she is unsure of when the light will turn red.
A dilemma zone is an area of the road before a stop line where a vehicle can neither travel through the intersection before the light turns red nor stop at the stop line due to the location of the vehicle with respect to the stop line and the current velocity of the vehicle.
Both the option zone and the dilemma zone may lead to undesirable outcome for both drivers and autonomously controlled vehicles.
Accordingly, alternative systems and methods for controlling vehicles through an intersection are desired.
In one embodiment, a method of controlling a vehicle with respect to an intersection, includes determining a distance of the vehicle with respect to the intersection, wherein the intersection includes a traffic light, determining a velocity of the vehicle, and receiving traffic light state information regarding the traffic light. The method also includes calculating, based on the distance of the vehicle to the intersection, the velocity of the vehicle, and the traffic light state information, a zone of interest with respect to the traffic light. The method further includes manipulating the velocity of the vehicle to modify a size of the zone of interest when a current trajectory of the vehicle will cause the vehicle to enter the zone of interest.
In another embodiment, a method of controlling a vehicle with respect to an intersection includes receiving traffic light state information regarding a traffic light at the intersection, wherein the traffic light state information includes a time remaining until a red state of the traffic light, determining a predicted position of the vehicle after the time remaining of a current state of the traffic light based on a current velocity of the vehicle, and determining a needed distance to stop the vehicle at a stop line of the intersection based on the current velocity of the vehicle. When the traffic light state information indicates a current green state and a distance between the stop line and the predicted position of the vehicle is less than the needed distance to stop such that the vehicle is predicted to enter a dilemma zone, the method includes outputting a reduced speed ratio signal to an accelerator control of the vehicle to decelerate the vehicle. When the traffic light state information indicates a current red state and a displacement between the predicted position and the stop line of the intersection is less than zero, the method includes outputting the reduced speed ratio signal to the accelerator control of the vehicle to decelerate the vehicle.
In yet another embodiment, a method of controlling a vehicle with respect to an intersection includes receiving traffic light state information regarding a traffic light, wherein the traffic light state information includes a current state and a minimum time remaining for the current state, and determining a distance to a stop line of the intersection. When the vehicle is within a predetermined distance of the stop line and the current state of the traffic light is a green state, the method includes calculating a predicted position of the vehicle at an end of the minimum time remaining for the green state, determining a maximum yellow passing distance XP from the stop line that is the distance that the vehicle can travel from when the traffic light changes to a yellow state until it changes to a red state, and determining a minimum stopping distance XS from the stop line. The method also includes, when the vehicle is within a predetermined distance of the stop line and the current state of the traffic light is a green state, determining a zone of interest prior to the stop line, which is an area defined by a difference between the greater of the maximum yellow passing distance XP and the minimum stopping distance XS and the other of the maximum yellow passing distance XP and the minimum stopping distance XS. The method further includes, when the predicted position of the vehicle is within the zone of interest, controlling the vehicle to decelerate such that the predicted position of the vehicle is not within the zone of interest.
The embodiments set forth in the drawings are illustrative and exemplary in nature and not intended to limit the disclosure. The following detailed description of the illustrative embodiments can be understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which:
The embodiments disclosed herein describe systems and methods for controlling a vehicle with respect to an intersection. Drivers of vehicles and autonomous vehicles may encounter a dilemma zone or an option zone (collectively referred to herein as a “zone of interest”) near an intersection with a traffic light. A traffic light may have a green light that is illuminated for a first period of time, a yellow light that is illuminated for a second period of time and a red light that is illuminated for a third period of time.
Embodiments of the present disclosure assist in navigating a vehicle with respect to a zone of interest of an intersection. An option zone is an area of the road before a stop line of an intersection where a traffic light is yellow and a driver could drive through the intersection before the traffic light turns red or stop at the stop line. However, the driver may be indecisive and hesitate to stop the vehicle or drive through the intersection because he or she is unsure of when the light will turn red.
A dilemma zone is an area of the road before a stop line where a vehicle can neither travel through the intersection nor stop at the stop line before the light turns red due to the location of the vehicle with respect to the stop line and the current velocity of the vehicle.
As described in detail herein, embodiments of the present disclosure predict when a vehicle (whether driven manually by a human or autonomously by computer control) will end up in, and be affected by, a zone of interest, and control the speed of the vehicle to minimize the zone of interest so that it is avoided. Embodiments receive traffic light state information and monitor the trajectory of the vehicle to predict when it will be affected by a zone of interest, and may reduce the speed of the vehicle in advance of the intersection to avoid the zone of interest.
Various embodiments of systems and methods for controlling a vehicle with respect to an intersection to avoid a zone of interest are described in detail below.
Referring now to
Referring now to
In embodiments of the present disclosure, the vehicle 100 receives the traffic light state information from an external source, such as from the traffic light itself (e.g., by a vehicle-to-infrastructure communication protocol), from a dedicated electronic communication device proximate the intersection (e.g., by a vehicle-to-infrastructure communication protocol), or from a remote server (e.g., by a wireless communication protocol). The traffic light state information may include, without limitation, a current state (i.e., the state that is currently active), one or more scheduled states, and a minimum time remaining for the current state, a minimum time remaining for the one or more scheduled states. In some embodiments, the traffic light state information may also include a maximum time remaining for the current state and the one or more scheduled states.
The vehicle 100 receives the traffic light state information and uses it to predict a zone of interest, and whether or not the vehicle 100 will enter or otherwise be affected by the zone of interest. The dilemma zone and the option zone (i.e., the zones of interest) will be described in detail below.
Referring once again to
Referring now to
Referring to both
The dilemma zone 30 can also be reduced by the control methods and systems of the present disclosure.
Thus, embodiments of the present disclosure are configured to manipulate the velocity of the vehicle to modify a size of the zone of interest by determining a distance of the vehicle with respect to the intersection, determining a velocity of the vehicle, receiving traffic light state information, and calculating the zone of interest using the distance of the vehicle to the intersection, the velocity of the vehicle, and the traffic light state information.
Referring now to
L−V*Y>0 and V*V/(2*D)<L
For the case of Y=3 seconds and D=1 m/s2, the area above plot line 202 is the case where the vehicle can pass the stop line (L−V*Y>0) and the area below plot line 201 is the case where the vehicle can stop before the stop line at D=1 m/s2 (V*V/(2*D)<L) The combinations of L and V for the dilemma zone are shown in the shaded area 203 of the graph of
Referring now to
where:
XS is the minimum stopping distance,
XP is the maximum yellow passing distance,
Xtg is the predicted distance (i.e., the predicted location at the conclusion of the green light at tg),
v is the velocity of the vehicle,
a is the acceleration of the vehicle,
amax is the maximum acceleration of the vehicle,
dmax is the maximum deceleration of the vehicle,
ty is the duration of the yellow signal,
tg is the duration of the green signal,
L is the length of the vehicle plus the proceed distance during the actuator of the vehicle reaction time, and
α, β are weighting factors such as 0<α≤1, 0<β≤1.
The remaining time ty and tg is received from the traffic light, such as by vehicle-to-infrastructure (V2I) protocol, for example. By using the time information of the traffic light state information that is received, XP, XS and Xtg is estimated using Equations (1)-(3) above to predict the risk of the vehicle 100 being in the option zone at the conclusion of time tg. The weighting factors α, β are related to ty to adjust XP to optimize the braking input. These weighting factors provide for smooth control of the vehicle for passenger comfort.
If the vehicle 100 is likely to be present in the option zone the maximum yellow passing distance XP, the minimum stopping distance XS and the predicted distance Xtg can be controlled by changing the acceleration of the vehicle 100. This will cause the vehicle 100 to avoid being in the option zone after time tg. As shown in
Similarly, the acceleration of the vehicle 100 can be controlled to reduce the size of a dilemma zone 30.
It is noted that the process for determining whether or not the vehicle will be within a zone of interest may be initiated at a predetermined distance from the stop line of the Tr (i.e., the distance from the stop line is less than a predetermined threshold) so that the vehicle may be decelerated in a smooth manner without causing discomfort to the passengers of the vehicle.
Referring now to
A traffic light detection module 305 is configured to detect the presence of a traffic light as the vehicle approaches an intersection and receives traffic light state information. The traffic light detection module 305 may detect a traffic light by any means. In the example of
The example system 300 further includes vehicle location module 306 that outputs a vehicle position. The vehicle location module 306 may determine the location of the vehicle by any means. In the example of
The example system 300 further includes a map module 307 that maps the traffic light state, the current traffic light state remaining time, the vehicle state (e.g., it receives the parameters of the vehicle, such as velocity, acceleration, and the like), and localized data on a map. The map module 307 may access one or more maps of the environment, such as a high definition map. The map module 307 outputs a position of the vehicle with respect to map data as well as the state of the vehicle.
A speed controller module 310 is responsible for detecting a zone of interest, and decelerating the vehicle 100 when needed. The speed controller module 310 receives as input the traffic light status information (e.g., the signal state remaining time for the current state and the scheduled states) from the traffic light detection module 305 and the vehicle position and vehicle state from the map module 307. The speed controller module 310 detects the zone of interest with the signal state and remaining time and the vehicles position with respect to the map data and/or real-time sensor data from the one or more cameras 303 and the one or more LiDAR sensors 304. The output of the speed controller module 310 is a control signal that is provided to a vehicle controller, such as a controller for controlling an accelerator for the vehicle 100 (e.g., the gas pedal for an internal combustion engine or the accelerator pedal for an electric vehicle).
In some embodiments, the speed controller module 310 decelerates the vehicle 100 in a slow and controlled manner that is comfortable to the passengers of the vehicle 100. When the vehicle 100 is within a predetermined distance of the stop line and the current state of the traffic light is a green state, a zone of interest routine may be performed by the speed controller. For example, when the traffic light is green and the predicted position Xtg is beyond the stop line (i.e., the predicted distance between the predicted position Xtg and the stop line 15 is negative (any position beyond the stop line 15 is negative), the vehicle 100 can pass through the intersection before the light turns yellow. In this instance, the speed controller module 310 takes no action.
However, when the speed controller module 310 determines that the vehicle 100 will be in a zone of interest (i.e., an area defined by a difference between the greater of the maximum yellow passing distance XP and the minimum stopping distance XS and the other of the maximum yellow passing distance XP and the minimum stopping distance XS), a reduced speed ratio is applied to the output of the speed controller module 310 to incrementally reduce the speed of the vehicle. For example, a reduced speed ratio may be 0.01. Each time the reduced speed ratio is applied, the speed controller module 310 again determines whether or not the vehicle 100 will be in the zone of interest. The reduced speed ratio will be updated again if it is not enough to avoid the zone of interest.
As an example, when a distance between the stop line 15 and the predicted position Xtg of the vehicle is less than a minimum stopping distance such that the vehicle will stop within a dilemma zone, the speed controller outputs the reduced speed ratio. As another example, when the traffic light state information indicates a current red state and a displacement between the predicted position and the stop line of the intersection is less than zero, the speed controller module 310 outputs the reduced speed ratio to decelerate the vehicle 100.
Each of the one or more processors 402 may be any device capable of executing computer readable and executable instructions. Accordingly, each of the one or more processors 402 may be a controller, an integrated circuit, a microchip, a computer, or any other computing device. The one or more processors 402 are coupled to a communication path 404 that provides signal interconnectivity between various modules of the computing system 400. Accordingly, the communication path 404 may communicatively couple any number of processors 402 with one another, and allow the modules coupled to the communication path 404 to operate in a distributed computing environment. Specifically, each of the modules may operate as a node that may send and/or receive data. As used herein, the term “communicatively coupled” means that coupled components are capable of exchanging data signals with one another such as, for example, electrical signals via conductive medium, electromagnetic signals via air, optical signals via optical waveguides, and the like.
Accordingly, the communication path 404 may be formed from any medium that is capable of transmitting a signal such as, for example, conductive wires, conductive traces, optical waveguides, or the like. In some embodiments, the communication path 404 may facilitate the transmission of wireless signals, such as WiFi, Bluetooth®, Near Field Communication (NFC) and the like. Moreover, the communication path 404 may be formed from a combination of mediums capable of transmitting signals. In one embodiment, the communication path 404 comprises a combination of conductive traces, conductive wires, connectors, and buses that cooperate to permit the transmission of electrical data signals to components such as processors, memories, sensors, input devices, output devices, and communication devices. Accordingly, the communication path 404 may comprise a vehicle bus, such as for example a LIN bus, a CAN bus, a VAN bus, and the like. Additionally, it is noted that the term “signal” means a waveform (e.g., electrical, optical, magnetic, mechanical or electromagnetic), such as DC, AC, sinusoidal-wave, triangular-wave, square-wave, vibration, and the like, capable of traveling through a medium.
The computing system 400 includes one or more memory modules 406 coupled to the communication path 404. The one or more memory modules 406 may comprise RAM, ROM, flash memories, hard drives, or any device capable of storing computer readable and executable instructions such that the computer readable and executable instructions can be accessed by the one or more processors 402. The computer readable and executable instructions may comprise logic or algorithm(s) written in any programming language of any generation (e.g., 1GL, 2GL, 3GL, 4GL, or 5GL) such as, for example, machine language that may be directly executed by the processor, or assembly language, object-oriented programming (OOP), scripting languages, microcode, etc., that may be compiled or assembled into computer readable and executable instructions and stored on the one or more memory modules 406. Alternatively, the computer readable and executable instructions may be written in a hardware description language (HDL), such as logic implemented via either a field-programmable gate array (FPGA) configuration or an application-specific integrated circuit (ASIC), or their equivalents. Accordingly, the methods described herein may be implemented in any conventional computer programming language, as pre-programmed hardware elements, or as a combination of hardware and software components.
The one or more memory modules 106 may be configured as volatile and/or nonvolatile memory and, as such, may include random access memory (including SRAM, DRAM, and/or other types of RAM), flash memory, secure digital (SD) memory, registers, compact discs (CD), digital versatile discs (DVD), and/or other types of non-transitory computer-readable mediums. The one or more memory modules 406 include logic in the form of computer readable instructions that perform the functionalities described herein, such as the traffic light detection module 305, the vehicle location module 306, the map module 307, and the speed controller module 310. Additional logic used to support these functionalities may be stored in the one or more memory modules 406 and/or in remote memory modules.
The data storage device 411, which may generally be a storage medium, may contain one or more data repositories for storing data that is received and/or generated, and may be any physical storage medium, including, but not limited to, a hard disk drive (HDD), memory, removable storage, and/or the like. While the data storage device 411 is depicted as a local device, it should be understood that the data storage device 70 may be a remote storage device, such as, for example, a server computing device or the like. In some embodiments, the data storage device stores map information, such as the high-definition map data described above. It should be understood that the data storage device is not provided in some embodiments.
Still referring to
It should now be understood that embodiments of the present disclosure are directed to systems and methods for controlling a vehicle with respect to an intersection to avoid a zone of interest, such as a dilemma zone or an option zone. Embodiments predict a zone of interest in advance of the vehicle arriving at the intersection and control the velocity of the vehicle when the vehicle is predicted to be within the zone of interest. Thus, drivers and autonomous vehicles will avoid a dilemma zone situation where the vehicle cannot proceed through the intersection before the traffic light turns red nor stop at the stop line, and avoid an option zone where a driver may hesitate in deciding whether to drive through the intersection or stop at the stop line.
It is noted that the terms “substantially” and “about” may be utilized herein to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. These terms are also utilized herein to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue.
While particular embodiments have been illustrated and described herein, it should be understood that various other changes and modifications may be made without departing from the spirit and scope of the claimed subject matter. Moreover, although various aspects of the claimed subject matter have been described herein, such aspects need not be utilized in combination. It is therefore intended that the appended claims cover all such changes and modifications that are within the scope of the claimed subject matter.