SYSTEMS, METHODS, AND NON-TRANSITORY COMPUTER-READABLE MEDIUMS FOR ESTIMATING A RESIDUAL TIME OF A CURRENT TRAFFIC SIGNAL
20240282191 ยท 2024-08-22
Assignee
- Toyota Motor Engineering & Manufacturing North America, Inc. (Plano, TX, US)
- Toyota Jidosha Kabushiki Kaisha (Toyota-Shi, JP)
Inventors
Cpc classification
G08G1/012
PHYSICS
International classification
Abstract
Systems, methods, and non-transitory computer-readable mediums for estimating a residual time of a current traffic signal are provided. The methods include estimating an initial residual time of a current traffic signal until a change of the current traffic signal based on a signal plan and information received from vehicle sensors, collecting information about a vehicle queue, estimating a residual time of the current traffic signal until the change of the current traffic signal based on the information about the vehicle queue, and estimating a final residual time of the current traffic signal until the change of the current traffic signal based on the initial residual time and the estimated residual time of the current traffic signal.
Claims
1. A method comprising: estimating an initial residual time of a current traffic signal until a change of the current traffic signal based on a signal plan and information received from vehicle sensors; collecting information about a vehicle queue; estimating a residual time of the current traffic signal until the change of the current traffic signal based on the information about the vehicle queue; and estimating a final residual time of the current traffic signal until the change of the current traffic signal based on the initial residual time and the estimated residual time of the current traffic signal.
2. The method according to claim 1, further comprising: estimating a first residual time of the current traffic signal at a first time until the change of the current traffic signal based on a moving average of the estimated residual time; estimating a second residual time of the current traffic signal at a second time until the change of the current traffic signal based on the moving average of the estimated residual time; and determining the second residual time at the second time as the final residual time in response to determining that a difference between the first residual time at the first time and the second residual time at the second time is lower than a threshold value.
3. The method according to claim 1, wherein: the current traffic signal comprises a first red signal, a second red signal, a third red signal, and a first green signal, and a pedestrian moves in the second red signal.
4. The method according to claim 3, further comprising: detecting the current traffic signal by the vehicle sensors; in response to detecting the current traffic signal, determining a middle point of a total time of the first red signal, the second red signal, and the third red signal as the initial residual time.
5. The method according to claim 3, further comprising: detecting the current traffic signal and movement of other vehicle excluded from the vehicle queue by the vehicle sensors; and in response to detecting the current traffic signal being the second red signal and detecting the movement of other vehicle being a different direction from the vehicle queue, determining a sum of a total time of the third red signal and a middle point of a time of the second red signal as the initial residual time.
6. The method according to claim 3, further comprising: in response to detecting the current traffic signal by the vehicle sensors being the first green signal, determining a middle point of a total time of the first green signal as the initial residual time.
7. The method according to claim 6, further comprising: estimating traffic flow rate, traffic density, or both; estimating an average speed of backward propagation of the vehicle queue based on the estimated traffic flow rate, the estimated traffic density, or both; estimating a time passed from the first green signal started based on the average speed of the backward propagation of the vehicle queue and a discharged length of the vehicle queue; and estimating the final residual time of the current traffic signal until the change of the current traffic signal based on the initial residual time, and the estimated time passed from the first green signal started.
8. The method according to claim 3, further comprising: detecting the current traffic signal and movement of the pedestrian by the vehicle sensors; and in response to detecting the current traffic signal being the second red signal and detecting the movement of the pedestrian: subtracting a time of crossing a road of the pedestrian from a total time of the second red signal to obtain a remaining time; and determining a sum of a total time of the third red signal and the remaining time as the initial residual time.
9. The method according to claim 3, further comprising: detecting the current traffic signal and a signal for the pedestrian by the vehicle sensors; in response to detecting the current traffic signal being the second red signal and detecting the signal for the pedestrian being blinking, determining a sum of a total time of the third red signal and a middle point of the time of blinking the signal for the pedestrian as the initial residual time.
10. The method according to claim 3, further comprising: estimating traffic flow rate, traffic density, or both; estimating an average speed of backward propagation of the vehicle queue based on the estimated traffic flow rate, the estimated traffic density, or both; estimating a time passed from the first red signal started based on the average speed of the backward propagation of the vehicle queue and a length of the vehicle queue; and estimating the final residual time of the current traffic signal until the change of the current traffic signal based on the initial residual time, and the estimated time passed from the first red signal started.
11. The method according to claim 10, wherein the traffic flow rate, the traffic density, or both, are estimated by the vehicle sensors.
12. The method according to claim 10, wherein the average speed of the backward propagation of the vehicle queue is determined using a macroscopic traffic model.
13. A system comprising: a controller programmed to: estimate an initial residual time of a current traffic signal until a change of the current traffic signal based on a signal plan and information received from vehicle sensors; collect information about a vehicle queue; estimate a residual time of the current traffic signal until the change of the current traffic signal based on the information about the vehicle queue; and estimate a final residual time of the current traffic signal until the change of the current traffic signal based on the initial residual time and the estimated residual time of the current traffic signal.
14. The system according to claim 13, wherein the controller is further programmed to: estimate a first residual time of the current traffic signal at a first time until the change of the current traffic signal based on a moving average of the estimated residual time; estimate a second residual time of the current traffic signal at a second time until the change of the current traffic signal based on the moving average of the estimated residual time; and determine the second residual time at the second time as the final residual time in response to determining that a difference between the first residual time at the first time and the second residual time at the second time is lower than a threshold value.
15. The system according to claim 13, wherein: the current traffic signal comprises a first red signal, a second red signal, a third red signal, and a first green signal, and a pedestrian moves in the second red signal.
16. The system according to claim 15, wherein the controller is further programmed to: detect the current traffic signal by the vehicle sensors; in response to detecting the current traffic signal, determine a middle point of a total time of the first red signal, the second red signal, and the third red signal as the initial residual time.
17. The system according to claim 15, wherein the controller is further programmed to: detect the current traffic signal and movement of other vehicle excluded from the vehicle queue by the vehicle sensors; and in response to detecting the current traffic signal being the second red signal and detecting the movement of other vehicle being a different direction from the vehicle queue, determine a sum of a total time of the third red signal and a middle point of a time of the second red signal as the initial residual time.
18. The system according to claim 15, wherein the controller is further programmed to: in response to detecting the current traffic signal by the vehicle sensors being the first green signal, determine a middle point of a total time of the first green signal as the initial residual time.
19. The system according to claim 18, wherein the controller is further programmed to: estimate traffic flow rate, traffic density, or both; estimate an average speed of backward propagation of the vehicle queue based on the estimated traffic flow rate, the estimated traffic density, or both; estimate a time passed from the first green signal started based on the average speed of the backward propagation of the vehicle queue and a discharged length of the vehicle queue; and estimate the final residual time of the current traffic signal until the change of the current traffic signal based on the initial residual time, and the estimated time passed from the first green signal started.
20. A non-transitory computer-readable medium that, when executed by a controller, cause the controller to: estimate an initial residual time of a current traffic signal until a change of the current traffic signal based on a signal plan and information received from vehicle sensors; collect information about a vehicle queue; estimate a residual time of the current traffic signal until the change of the current traffic signal based on the information about the vehicle queue; and estimate a final residual time of the current traffic signal until the change of the current traffic signal based on the initial residual time and the estimated residual time of the current traffic signal.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The following detailed description of specific embodiments of the present disclosure can be best understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which:
[0010]
[0011]
[0012]
[0013]
[0014]
[0015]
[0016] Reference will now be made in greater detail to various embodiments of the present disclosure, some embodiments of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or similar parts.
DETAILED DESCRIPTION
[0017] The embodiments disclosed herein include systems, methods, and non-transitory computer-readable mediums for estimating a residual time of a current traffic signal. The systems, methods, and non-transitory computer-readable mediums accurately estimate a residual time of a current traffic signal by estimating an initial residual time of a current traffic signal until a change of the current traffic signal, estimating a residual time of the current traffic signal until the change of the current traffic signal based on the information about the vehicle queue; and estimating a final residual time of the current traffic signal until the change of the current traffic signal based on the initial residual time and the estimated residual time of the current traffic signal using a signal plan and vehicles sensors.
[0018]
[0019] Referring to
[0020] The ego vehicle 110 may be a vehicle including an automobile or any other passenger or non-passenger vehicle such as, for example, a terrestrial, aquatic, and/or airborne vehicle. In some embodiments, the ego vehicle 110 may be an autonomous driving vehicle. The ego vehicle 110 may be an autonomous vehicle that navigates its environment with limited human input or without human input. The ego vehicle 110 may be equipped with internet access and share data with other devices both inside and outside the ego vehicle 110. The ego vehicle 110 may communicate with the server 240, and transmit its data to the server 240. For example, the ego vehicle 110 transmits information about its current location and destination, its environment, information about a current driver, information about a task that it is currently implementing, and the like. The ego vehicle 110 may include an actuator configured to move the ego vehicle 110.
[0021] Referring to
[0022] The vehicle queue 120 may include a plurality of vehicles. In some embodiments, the vehicle queue 120 may exist and stop at the intersection, an on-ramp of a highway, an off-ramp of a highway, or combinations thereof.
[0023] The signal plan may include information about various phases for different vehicles and pedestrian movements, phase durations for different vehicles and pedestrian movements, and a ring-and-barrier diagram. The ring-and-barrier diagram may separate conflicting phases and plan sequences of the phases.
[0024] The signal plan may include the current traffic signal 150. The signal plan may be stored in the server 240, such as a cloud server. The current traffic signal 150 may include a ring-and-barrier diagram. The current traffic signal 150 may include two rings. Phases of a ring may operate one after another. For instance, phases 1 and 5 may operate together for the duration of the phases, then phases 2 and 6 operate, and so on. In a fixed-time signal, the phase durations (?t.sub.1-?t.sub.4) are fixed, while in actuated or adaptive signals, the durations may vary between a minimum and maximum values.
[0025] Still referring to
[0026] The current traffic signal 150 may be detected by the vehicle sensors. In embodiments, the current traffic signal 150 may be detected by the vehicle sensors, such as a camera, of the ego vehicle 110. In embodiments, the current traffic signal 150 may be stored in the server 240, such as a cloud server.
[0027] Referring to
[0028] Referring to
[0029] In response to detecting the current traffic signal 150 being the second red signal 152 and the movement of other vehicles (e.g., vehicles moving in a direction perpendicular to the driving direction of the ego vehicle 110), the ego vehicle 110 may estimate that the current time is within the period of the second red signal 152, i.e., an uncertainty range, and determine a sum of a total time of the third red signal 153 and a middle point of a time of the second red signal 152 as the initial residual time. For example, as shown in the below equation 2, a sum
of a total time (?t.sub.?3) of the third red signal 153 and a middle point of a time
or the second red signal 152 may be determined as the initial residual time (?t.sub.0.sup.res).
[0030] Referring to
[0031] The ego vehicle 110 may estimate a residual time of the current traffic signal 150 until the change of the current traffic signal 150 based on the information about the vehicle queue 120. In some embodiments, the ego vehicle 110 may estimate traffic flow rate on the road on which the ego vehicle 110 is driving, traffic density on the road on which the ego vehicle 110 is driving, or both. In some embodiments, the traffic flow rate, the traffic density, or both, may be estimated by the vehicle sensors of the ego vehicle 110, the vehicle sensors of vehicles in the vehicle queue 120, or both. In some embodiments, the vehicles in the vehicle queue 120 may estimate the traffic flow rate, the traffic density, or both and then transfer the data of the traffic flow rate, the traffic density, or both to the server 240. The ego vehicle 110 may receive the data of the traffic flow rate, the traffic density, or both from the server 240.
[0032] Using a macroscopic traffic model shown in
[0033] The ego vehicle 110 may estimate the average speed (v.sub.sw) of the backward propagation of the vehicle queue 120 based on the estimated traffic flow rate, the estimated traffic density, or both. The backward propagation of the vehicle queue 120 occurs as more vehicles join the vehicle queue 120 and stop. For example, the ego vehicle 110 may estimate the average speed (v.sub.sw) of the backward propagation of the vehicle queue 120 based on the estimated traffic flow rate, the estimated traffic density, or both, using a macroscopic traffic model as shown in
[0034] Referring to ) passed from the first red signal 151 started based on the average speed (v.sub.sw) of the backward propagation of the vehicle queue 120 and a length of the vehicle queue 120. The length of the vehicle queue 120 may refer to a length from a front side of the first vehicle in the vehicle queue 120 from the signal of the intersection and a backside of the closest vehicle in the vehicle queue 120 from the ego vehicle 110. For example, as shown in the below equation 3, a time (?
) passed from the first red signal 151 started may be estimated by a length of the vehicle queue 120 divided by the average speed (v.sub.sw). In some embodiments, using a machine learning model, the ego vehicle 110 may estimate a time (?
) passed from the first red signal 151 started based on the average speed (v.sub.sw) of the backward propagation of the vehicle queue 120 and a length of the vehicle queue 120.
[0035] Still referring to ) of a red signal until the first green signal 154 begins based on a total red signal time (t.sub.R) and a time (?
) passed from the first red signal 151 started. For example, as shown in the below equation 4, the residual time (
) of a red signal until the first green signal 154 begins may be estimated by subtracting a time (?
) passed from the first red signal 151 started from a total red signal time (t.sub.R).
[0036] Still referring to
[0037] where y is a smoothing factor between 0 and 1; ?t.sub.residual.sup.0 is an initial residual time; is the estimated residual time of a red signal until the first green signal 154 begins; ?t
is the estimated residual time of a red signal until the first green signal 154 begins at the previous time step; ?t.sub.step is a time passed from the previous time step; and ?t
is the residual time of the current traffic signal 150 until the change of the current traffic signal 150.
[0038] Referring to when t=t.sub.1 according to Equation 6. The ego vehicle 110 may estimate a second residual time of the current traffic signal 150 until the change of the current traffic signal 150 at a second time (t.sub.2) based on the moving average of the estimated residual time, i.e., ?t
when t=t.sub.2 according to Equation 6. The second time is different from the first time. The second time is after the first time. The ego vehicle 110 may determine the second residual time of the current traffic signal 150 until the change of the current traffic signal 150 at the second time as the final residual time in response to determining that a difference between the first residual time of the current traffic signal 150 until the change of the current traffic signal 150 at the first time and the second residual time of the current traffic signal 150 until the change of the current traffic signal 150 at the second time is lower than a threshold value.
[0039] For example, the ego vehicle 110 may terminate estimating the residual time of the current traffic signal 150 until the change of the current traffic signal 150 in response to determining that a new estimated residual time, such as a second residual time, is close to the previously estimated residual time, such as a first residual time, as shown in Equation 6.
where ? is a design parameter threshold.
[0040]
[0041] Referring to
[0042] The communication path 214 may be formed from any medium that is capable of transmitting a signal such as conductive wires, conductive traces, optical waveguides, or the like. In some embodiments, the communication path 214 may facilitate the transmission of wireless signals, such as WiFi, Bluetooth?, Near Field Communication (NFC), and the like. The communication path 214 may be formed from a combination of mediums capable of transmitting signals. In one embodiment, the communication path 214 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. The communication path 214 may comprise a vehicle bus, such as 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.
[0043] The vehicle system 210 includes one or more memory modules 216 coupled to the communication path 214 and may contain non-transitory computer-readable medium comprising RAM, ROM, flash memories, hard drives, or any device capable of storing machine-readable and executable instructions such that the machine-readable and executable instructions can be accessed by the one or more processors 212. The machine-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 machine-readable and executable instructions and stored in the one or more memory modules 216. The machine-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. 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 processors 212 along with the one or more memory modules 216 may operate as a controller for the vehicle system 210.
[0044] Still referring to
[0045] In some embodiments, one or more sensors 218 include one or more imaging sensors configured to operate in the visual and/or infrared spectrum to sense visual and/or infrared light. In some embodiments, one or more sensors 218 include one or more LIDAR sensors, radar sensors, sonar sensors, or other types of sensors for gathering data that could be integrated into or supplement the data collection. Ranging sensors like radar sensors may be used to obtain rough depth and speed information for the view of the vehicle system 210.
[0046] The vehicle system 210 includes a satellite antenna 215 coupled to the communication path 214 such that the communication path 214 communicatively couples the satellite antenna 215 to other modules of the vehicle system 210. The satellite antenna 215 is configured to receive signals from global positioning system satellites. In one embodiment, the satellite antenna 215 includes one or more conductive elements that interact with electromagnetic signals transmitted by global positioning system satellites. The received signal is transformed into a data signal indicative of the location (e.g., latitude and longitude) of the satellite antenna 215 or an object positioned near the satellite antenna 215, by one or more processors 212.
[0047] The vehicle system 210 includes one or more vehicle sensors 213. Each of one or more vehicle sensors 213 is coupled to the communication path 214 and communicatively coupled to one or more processors 212. One or more vehicle sensors 213 may include one or more motion sensors for detecting and measuring motion and changes in the motion of the vehicle system 210. The motion sensors may include inertial measurement units. Each of the one or more motion sensors may include one or more accelerometers and one or more gyroscopes. Each of one or more motion sensors transforms sensed physical movement of the vehicle into a signal indicative of an orientation, a rotation, a velocity, or an acceleration of the vehicle.
[0048] Still referring to
[0049] The vehicle system 210 may connect with one or more external vehicle systems and/or external processing devices (e.g., a server 240) via a direct connection. The direct connection may be a vehicle-to-vehicle connection (V2V connection), a vehicle-to-everything connection (V2X connection), or a mmWave connection. The V2V or V2X connection or mmWave connection may be established using any suitable wireless communication protocols discussed above. A connection between vehicles may utilize sessions that are time-based and/or location-based. In embodiments, a connection between vehicles or between a vehicle and an infrastructure element may utilize one or more networks to connect, which may be in lieu of, or in addition to, a direct connection (such as V2V, V2X, mmWave) between the vehicles or between a vehicle and an infrastructure.
[0050] Vehicles may function as infrastructure nodes to form a mesh network and connect dynamically on an ad-hoc basis. In this way, vehicles may enter and/or leave the network at will, such that the mesh network may self-organize and self-modify over time. The network may include vehicles forming peer-to-peer networks with other vehicles or utilizing centralized networks that rely upon certain vehicles and/or infrastructure elements. The network may include networks using the centralized server and other central computing devices to store and/or relay information between vehicles.
[0051] Still referring to
[0052] Still referring to
[0053] It should be understood that the components illustrated in
[0054]
[0055] Referring to
[0056] Referring to
[0057] Referring to
[0058] Referring to ) passed from the first red signal 151 started based on the average speed (v.sub.sw) of the vehicle queue 120 and a length of the vehicle queue 120, for example, as shown in the above Equation 3 or using a machine learning model. The controller may estimate a residual time (
) of a red signal until the first green signal 154 begins based on a total red signal time (t.sub.R) and a time (?
) passed from the first red signal 151 started, for example, as shown in the above Equation 4. The controller may estimate the residual time of the current traffic signal 150 until the change of the current traffic signal 150 using a moving average method, for example, as shown in the above Equation 5. For example, referring to
) passed from the first green signal 154 started based on the average speed (v.sub.sw) of the vehicle queue 120 and a discharged length of the vehicle queue 120, for example, as shown in the below Equation 8, or using a machine learning model. The controller may estimate a residual time (
) of a green signal based on a total green signal time (t.sub.R) and a time (?
) passed from the first green signal 154 started, for example, as shown in the below Equation 9.
[0059] Referring to
[0060]
[0061] Referring to
[0062] Still referring to
[0063] Referring to
of a total time (t.sub.G) of the first green signal 154 may be determined as the initial residual time (?t.sub.0.sup.res).
[0064] Referring to
[0065] Referring to ) passed from the first green signal 154 started based on the average speed (v.sub.sw) of the vehicle queue 120 and a discharged length of the vehicle queue 120. The term discharged length of the vehicle queue 120 may refer to a length of the vehicle queue 120 that has been discharged since the beginning of the first green signal 154. For example, as shown in the below equation 8, a time (?
) passed from the first green signal 154 started may be estimated by a discharged length of the vehicle queue 120 divided by the average speed (v.sub.sw). In some embodiments, using a machine learning model, the ego vehicle 110 may estimate a time (?
) passed from the first green signal 154 started based on the average speed (v.sub.sw) of the vehicle queue 120 and a discharged length of the vehicle queue 120.
[0066] Still referring to ) of a green signal based on a total green signal time (t.sub.R) and a time (?
) passed from the first green signal 154 started. For example, as shown in the below equation 9, the residual time (
) of a green signal may be estimated by subtracting a time (?
) passed from the first green signal 154 started from a total green signal time (t.sub.G).
[0067] Similar to
[0068] Similar to
[0069]
[0070] Referring to
[0071] The ego vehicle 110 may detect the current traffic signal 150 and the movement of the pedestrian 130 by the vehicle sensors. The ego vehicle 110 may detect the current traffic signal 150 being the second red signal 152 and detect the movement of the pedestrian 130.
[0072] Still referring to
[0073] The ego vehicle 110 may determine a sum of a total time of the third red signal 153 and the remaining time as the initial residual time. For example, as shown in the below equation 10, the initial residual time (?t.sub.0.sup.res) may be determined as a sum of a total time (?t.sub.?3) of the third red signal 153 and the remaining time
[0074] Similar to
[0075] Similar to
[0076]
[0077] Referring to
[0078] The ego vehicle 110 may detect the current traffic signal 150 and a signal for the pedestrian 130 by the vehicle sensors. The ego vehicle 110 may detect the current traffic signal 150 being the second red signal 152 and detect the signal for the pedestrian 130 being blinking.
[0079] Still referring to
[0080] The ego vehicle 110 may determine a sum of a total time of the third red signal 153 and a middle point of the time of blinking the signal for the pedestrian 130 as the initial residual time. For example, as shown in the below equation 11, the initial residual time (?t.sub.0.sup.res) may be determined as a sum of a total time (?t.sub.?3) of the third red signal 153 and the middle point
of the time of blinking the signal for the pedestrian 130.
[0081] Similar to
[0082] Similar to
[0083] For the purposes of describing and defining the present disclosure, it is noted that reference herein to a variable being a function of a parameter or another variable is not intended to denote that the variable is exclusively a function of the listed parameter or variable. Rather, reference herein to a variable that is a function of a listed parameter is intended to be open ended such that the variable may be a function of a single parameter or a plurality of parameters.
[0084] It is noted that recitations herein of a component of the present disclosure being configured or programmed in a particular way, to embody a particular property, or to function in a particular manner, are structural recitations, as opposed to recitations of intended use. More specifically, the references herein to the manner in which a component is configured or programmed denotes an existing physical condition of the component and, as such, is to be taken as a definite recitation of the structural characteristics of the component.
[0085] It is noted that terms like preferably, commonly, and typically, when utilized herein, are not utilized to limit the scope of the claimed invention or to imply that certain features are critical, essential, or even important to the structure or function of the claimed invention. Rather, these terms are merely intended to identify particular aspects of an embodiment of the present disclosure or to emphasize alternative or additional features that may or may not be utilized in a particular embodiment of the present disclosure.
[0086] The order of execution or performance of the operations in examples of the disclosure illustrated and described herein is not essential, unless otherwise specified. That is, the operations may be performed in any order, unless otherwise specified, and examples of the disclosure may include additional or fewer operations than those disclosed herein. For example, it is contemplated that executing or performing a particular operation before, contemporaneously with, or after another operation is within the scope of aspects of the disclosure.
[0087] Having described the subject matter of the present disclosure in detail and by reference to specific embodiments thereof, it is noted that the various details disclosed herein should not be taken to imply that these details relate to elements that are essential components of the various embodiments described herein, even in cases where a particular element is illustrated in each of the drawings that accompany the present description. Further, it will be apparent that modifications and variations are possible without departing from the scope of the present disclosure, including, but not limited to, embodiments defined in the appended claims. More specifically, although some aspects of the present disclosure are identified herein as preferred or particularly advantageous, it is contemplated that the present disclosure is not necessarily limited to these aspects.
[0088] What is claimed is: