阅读说明：本技术 一种用于路口绿灯提醒的辅助驾驶方法和系统 (Auxiliary driving method and system for intersection green light reminding ) 是由 陈功 于 2021-09-29 设计创作，主要内容包括：本发明公开了一种用于路口绿灯提醒的辅助驾驶方法和系统。该方法包括：采集图像数据；分析图像,确定当前车道和红绿灯信息；若存在红绿灯,确定红绿灯的颜色；若红绿灯颜色为绿色,判断绿灯形状,若绿灯为圆形或绿灯为箭头形且该形状与车道信息匹配时,检测车辆当前速度；若距离大于等于设定值,等待第一反应时间后,检测车辆当前速度；若车辆当前速度等于零,生成提示信息。该系统包括：图像采集模块、信息处理与控制模块、距离采集模块、速度采集模块和提示模块。本发明可以帮助未意识到路口信号灯已变绿的驾驶人员快速调整驾驶状态,从而可以有效避免后方车辆积压,在一定程度上缓解城市道路交通压力。(The invention discloses an auxiliary driving method and system for intersection green light reminding. The method comprises the following steps: collecting image data; analyzing the image and determining the current lane and traffic light information; if the traffic light exists, determining the color of the traffic light; if the color of the traffic light is green, judging the shape of the green light, and if the green light is round or the green light is arrow-shaped and the shape is matched with the lane information, detecting the current speed of the vehicle; if the distance is larger than or equal to the set value, after waiting for the first reaction time, detecting the current speed of the vehicle; and if the current speed of the vehicle is equal to zero, generating prompt information. The system comprises: the device comprises an image acquisition module, an information processing and control module, a distance acquisition module, a speed acquisition module and a prompt module. The invention can help drivers who do not realize that the intersection signal lamps turn green to quickly adjust the driving state, thereby effectively avoiding backlog of vehicles and relieving traffic pressure of urban roads to a certain extent.)

1. An assistant driving method for intersection green light reminding, which is characterized by comprising the following steps:

s10 acquiring image data; s20 analyzing the image, determining the current lane information and judging whether there is traffic light in the image;

s30, if a traffic light exists, determining the color of the traffic light; s40, if the color of the traffic light is green, executing the following steps:

detecting a distance between a vehicle and a front object in response to detecting occurrence of a first event, wherein the first event is that a traffic light is circular in shape; in response to the occurrence of a second event, judging whether the lane information meets a second condition at the moment, and if the second condition is met, detecting the distance between the vehicle and the front object, wherein the second event is that the shape of a traffic light is an arrow shape, and the second condition is that the lane information is matched with the shape of the bright green light; s50, if the distance is larger than or equal to the set value, after waiting for the first reaction time, detecting the current speed of the vehicle; and S60, if the current speed of the vehicle is equal to zero, generating a prompt message.

2. The driving assistance method for green light reminding at an intersection as claimed in claim 1, wherein the step of determining the current lane information in step S20 further comprises the steps of: carrying out image graying processing; filtering the image; carrying out image binarization processing; acquiring a region of interest; acquiring a lane contour; detecting a current lane by adopting a Shi-Tomasi corner detection method; acquiring an inter-lane region-of-interest image; extracting edge information; calculating seven eigenvalues by using the Hu invariant moment; calculating the similarity of the Mahalanobis distance; the current lane marker is identified.

3. The driving assistance method for green light reminding at an intersection as claimed in claim 1, wherein the step of determining whether the traffic light exists in the image in the step S20 further comprises the steps of: performing color segmentation on the image; filtering the image by using a circularity method; the traffic light area is identified using the shape feature.

4. The driving assistance method for green light reminding at an intersection as claimed in claim 1, wherein the prompt message is that a buzzer continuously rings and an LED lamp continuously flashes.

5. A driving assistance system for performing the method of any one of claims 1-4, comprising:

an image acquisition module configured to acquire image data; the information processing and control module is configured to analyze the lane and traffic light information after acquiring the image data; a distance acquisition module configured to detect a distance of a vehicle from a forward object in response to detecting an occurrence of a first event, wherein the first event is a traffic light that is circular in shape; the distance acquisition module is further configured to judge whether the lane information at the moment meets a second condition through the information processing and control module after responding to the detection of the occurrence of a second event, and detect the distance between the vehicle and the front object if the second condition is met, wherein the second condition is that the lane information is matched with the shape of the lightened green light; the speed acquisition module is configured to detect the current speed of the vehicle after determining that the distance is greater than or equal to a first set value and waiting for a first reaction time through the information processing and control module; and the prompting module is configured to generate prompting information through the information processing and control module after detecting that the current speed of the vehicle is zero.

6. The driving assistance system according to claim 5, wherein the image acquisition module adopts a CMOS image sensing chip with model number OV 7670; the information processing and control module adopts a main control chip with the model number of STM32F407ZET 6; the distance acquisition module adopts an ultrasonic sensor with the model of UCM-40-R piezoelectric ceramic; the speed acquisition module adopts a Hall speed measurement sensor with the chip model A3144; the prompting module comprises a buzzer and an LED lamp.

7. The driving assistance system according to claim 6, wherein the connection relationship between each signal pin of the image sensing chip and the main control chip is as follows:

OV SDA is connected with PG 13;

OV SCL connected to PD 3;

the FIFO RCLK is connected with PB 4;

the FIFO WEN is connected with PB 3;

FIFO WRST is connected with PD 6;

the FIFO RRST is connected with PG 14;

FIFO OE is connected with PG 15;

OV VSYNC is connected with PA 8;

OV D [7:0] is connected with PC [7:0 ].

8. The driver assistance system of claim 6, wherein the ultrasonic sensor comprises two pieces of UCM-40-R piezoelectric ceramic; the signal input port of one chip is connected with the PA1 port of the main control chip, and the signal input port of the other chip is connected with the PA2 port of the main control chip.

9. The assistant driving system according to claim 6, wherein the output end of the Hall velocity sensor is connected with a port PF0 of the main control chip.

10. The driving assistance system according to claim 6, wherein the buzzer is connected with a port PE0 of the main control chip; the LED lamp is connected with the PF9 port of the main control chip.

Technical Field

The invention relates to the field of auxiliary driving of vehicles, in particular to an auxiliary driving method and system for intersection green light reminding.

Background

With the continuous improvement of the living standard of people and the continuous development of science and technology, the negative effects of traffic jam are obvious when the motor vehicles continuously break through innovation in quantity and quality and appearance. The driver of the vehicle is distracted, plays a mobile phone, reads a book and the like during waiting for green light at the intersection, so that the vehicle does not pass through the intersection or drive forwards in time after the signal light turns from red to green, the phenomenon of traffic jam is very common due to serious backlog of the vehicle, and the phenomenon also becomes one of the main reasons of traffic jam of the current road.

However, only some luxury vehicles with automatic driving function adopt the whole road condition sensing system, and the vehicle auxiliary control system of the common household vehicle mainly emphasizes the aspect of vehicle driving safety. The existing system with the sensing capability of all road conditions can detect the road conditions correctly and timely only by means of a mature navigation system on the market, and a vehicle-mounted system cannot work independently, so that the system has considerable limitation; and the auxiliary control system of the common household vehicle cannot prompt a driver to respond to the vehicle state in time due to the fact that the auxiliary control system cannot acquire road information in time.

The comparison document CN105185140B provides an auxiliary driving method and system, and the functions of camera shooting, navigation positioning, image analysis, driving reminding and the like are used for reminding a driver of a vehicle of the change of traffic lights in time, so that the driving of the vehicle is facilitated. However, the technical scheme still mainly depends on a navigation system to position the vehicle, so that the vehicle positioning is finished by connecting the navigation system with the GPS, the copyright problem is involved, the system is more complicated, and the method cannot be generally applied.

Disclosure of Invention

The invention aims to provide a driving assisting method and a driving assisting system for intersection green light reminding, which can be used for distinguishing the road condition of an intersection in real time when a vehicle waits for a red light, assisting a driver to make corresponding actions on the vehicle in time and reducing the occurrence of rear traffic jam caused by the fact that a front vehicle does not pass in time.

To achieve the above object, according to a first aspect of the present invention, there is provided a driving assistance method for an intersection green light reminder, comprising: s10 acquiring image data; s20 analyzing the image, determining the current lane information and judging whether there is traffic light in the image; s30, if a traffic light exists, determining the color of the traffic light; s40, if the color of the traffic light is green, executing the following steps: detecting a distance between a vehicle and a front object in response to detecting occurrence of a first event, wherein the first event is that a traffic light is circular in shape; in response to the occurrence of a second event, judging whether the lane information meets a second condition at the moment, and if the second condition is met, detecting the distance between the vehicle and the front object, wherein the second event is that the shape of a traffic light is an arrow shape, and the second condition is that the lane information is matched with the shape of the bright green light; s50, if the distance is larger than or equal to the set value, after waiting for the first reaction time, detecting the current speed of the vehicle; and S60, if the current speed of the vehicle is equal to zero, generating a prompt message.

Further, the step of determining the current lane information in step S20 further includes the steps of: carrying out image graying processing;

filtering the image; carrying out image binarization processing; acquiring a region of interest; acquiring a lane contour; detecting a current lane by adopting a Shi-Tomasi corner detection method; acquiring an inter-lane region-of-interest image; extracting edge information; calculating seven eigenvalues by using the Hu invariant moment; calculating the similarity of the Mahalanobis distance; the current lane marker is identified.

Further, the step of determining whether the traffic light exists in the image in step S20 further includes the following steps: performing color segmentation on the image; filtering the image by using a circularity method; the traffic light area is identified using the shape feature.

Further, the prompt information is that the buzzer continuously reminds and the LED lamp continuously flickers.

According to a second aspect of the present invention, there is provided a driving assistance system for performing the above method, comprising:

an image acquisition module configured to acquire image data; the information processing and control module is configured to analyze the lane and traffic light information after acquiring the image data; a distance acquisition module configured to detect a distance of a vehicle from a forward object in response to detecting an occurrence of a first event, wherein the first event is a traffic light that is circular in shape; the distance acquisition module is further configured to judge whether the lane information at the moment meets a second condition through the information processing and control module after responding to the detection of the occurrence of a second event, and detect the distance between the vehicle and the front object if the second condition is met, wherein the second condition is that the lane information is matched with the shape of the lightened green light; the speed acquisition module is configured to detect the current speed of the vehicle after determining that the distance is greater than or equal to a first set value and waiting for a first reaction time through the information processing and control module; and the prompting module is configured to generate prompting information through the information processing and control module after detecting that the current speed of the vehicle is zero.

Furthermore, the image acquisition module adopts a CMOS image sensing chip with the model number of OV 7670; the information processing and control module adopts a main control chip with the model number of STM32F407ZET 6; the distance acquisition module adopts an ultrasonic sensor with the model of UCM-40-R piezoelectric ceramic; the speed acquisition module adopts a Hall speed measurement sensor with the chip model A3144; the prompting module comprises a buzzer and an LED lamp.

Further, the connection relationship between each signal pin of the image sensing chip and the main control chip is as follows:

OV SDA is connected with PG 13;

OV SCL connected to PD 3;

the FIFO RCLK is connected with PB 4;

the FIFO WEN is connected with PB 3;

FIFO WRST is connected with PD 6;

the FIFO RRST is connected with PG 14;

FIFO OE is connected with PG 15;

OV VSYNC is connected with PA 8;

OV D [7:0] is connected with PC [7:0 ].

Further, the ultrasonic sensor comprises two pieces of UCM-40-R piezoelectric ceramics; the signal input port of one chip is connected with the PA1 port of the main control chip, and the signal input port of the other chip is connected with the PA2 port of the main control chip.

Furthermore, a power supply end of the Hall speed measuring sensor is connected with a system power supply, a grounding end of the Hall speed measuring sensor is connected with a system ground, and an output end of the Hall speed measuring sensor is connected with a PF0 port of the main control chip.

Further, the buzzer is connected with a PE0 port of the main control chip through a resistor and a triode; the LED lamp is connected with the PF9 port of the main control chip through a resistor.

Compared with the prior art, the invention has the beneficial effects that:

1. the invention can distinguish the road condition of the crossroad in real time when the vehicle waits for the red light, assists the driver to make corresponding action on the vehicle in time, and reduces the occurrence of rear traffic jam caused by the fact that the front vehicle does not pass in time;

2. the invention can independently operate, does not need to depend on a vehicle driving control system and external navigation, and only needs to provide power supply by means of a vehicle power supply, so that the invention can be installed in a vehicle by vehicle upgrading at a later stage even if the vehicle is not equipped with the system when leaving a factory, if a vehicle owner needs the system;

3. the invention has low price, and the hardware used by the system is all the equipment commonly existing in the current market;

4. the invention has simple logic structure and smaller development period and development cost.

Drawings

In order to more clearly illustrate the technical solution of the present invention, the drawings required by the present invention are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic flow chart of a driving assistance method according to an exemplary embodiment of the present invention.

Fig. 2 is a schematic structural diagram of a driving assistance system provided by the invention according to an exemplary embodiment.

Fig. 3 is a schematic diagram of lane image recognition processing in a driving assistance method according to an exemplary embodiment of the present invention.

Fig. 4 is a schematic diagram of a traffic light image recognition process in the driving assistance method according to an exemplary embodiment of the invention.

Fig. 5 is an overall hardware circuit diagram of a driving assistance system provided in accordance with an exemplary embodiment of the present invention.

Fig. 6 is a circuit diagram of an image capture module of a driving assistance system provided in accordance with an exemplary embodiment of the present invention.

Fig. 7 is a circuit diagram of a distance acquisition module of a driving assistance system provided in accordance with an exemplary embodiment of the present invention.

FIG. 8 is a circuit diagram of a speed acquisition module of a driver assistance system provided in accordance with an exemplary embodiment of the present invention

Fig. 9 is a circuit diagram of a prompt module of a driving assistance system provided in accordance with an exemplary embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The process of the method of the invention is shown in FIG. 1. Firstly, the step S10 is performed to collect image data, and then the step S20 is performed to analyze the obtained image data, so as to detect the current lane, obtain information of the ground guiding arrow in the current lane, and prepare for subsequent system judgment. Then, continuously analyzing the obtained image data, judging whether a traffic light is detected, if not, indicating that the vehicle is not positioned at a traffic light intersection, continuously detecting the current lane without making a response; if so, the system runs down. Step S30 is started to detect the color of the traffic light, whether the current traffic light is green is judged, if not, the current traffic light is in a red light state, the vehicle cannot pass, and no response is needed; if so, the step S40 of detecting the traffic light shape is started. The shapes of the lighted green lights on the road are only circular and arrow-shaped, if the circular green lights are lighted, lane matching is not needed, and the next step is directly executed; if the detected shape is an arrow shape, it needs to start to judge whether the green light shape is matched with the current lane, for example: the current ground road guide arrow is a left-turn arrow, and the shape of the lighted green light is also a left-turn arrow, so that information matching is described; or the current ground road guide arrow is a straight arrow, the shape of the lighted green light is a left-turning arrow, and the description information is not matched. If not, the lane does not have the same-row condition at present, no response is needed, and the color of the traffic light is continuously detected again; if the lane is matched with the traffic rule, the lane is allowed to run together from the traffic rule at present, but whether the vehicle can run or not is determined by the specific road condition. Therefore, it is also necessary to determine the road condition ahead. At this time, the radar is detected to be away from the front object in the step S50, then whether the distance between the front object and the vehicle reaches a set value is judged, if not, the front does not have the driving condition; if yes, the situation that no vehicle exists in front or the vehicle in front has already traveled a certain distance is indicated, and the running condition is met. The driver is given a certain reaction time at this time. Step S60 is to start the speed sensor to collect the vehicle speed after waiting for the first response time, and determine whether the vehicle is started according to the speed. If the speed is detected to be zero, indicating that the driver does not recover the driving state, executing step S70 to generate prompt information, making sound and light reminding, controlling the buzzer to sound continuously and the LED lamp to flash continuously; if the speed is not zero, the current driving state of the driver is good, and system reminding is not needed.

Further, the flow of the lane image recognition processing in the method of the present invention is shown in fig. 3. Firstly, the step S201 is carried out to carry out image graying processing on the obtained lane image, the image subjected to graying processing is easier to process and detect the image in the later period, and the calculation efficiency is improved. Then, the image filtering in step S202 is performed, and the captured image is affected by light, tree shadows, and other factors, so that useless noise is generated. These noises may interfere with the detection of the lane lines, resulting in a portion of the lane lines not being detected. In order to remove the influence of these noises, a filtering method is required to remove the noises in the image. The image can be divided into foreground and background, and the foreground is divided from the useless background. In this case, it is necessary to perform the binarization processing of the image on the filtered image in step S203. After the useful foreground data is segmented, the data needs to be further screened, step S204 is implemented to obtain the region of interest, the position of the lane line is roughly distinguished, so that efficiency can be improved, useful information on the road surface is found first and then detected, and therefore, not only can the useless information be eliminated, but also the detection efficiency can be improved. Then, step S205 is performed to extract a lane contour by using a Canny edge detector, so as to prepare for subsequent lane detection. In order to ensure the real-time performance of image processing, step S206 is further performed to detect the current lane by using a Shi-Tomasi corner detection method, and Shi-Tomasi corner detection is performed to detect lane lines in real time by comparing the corner information of the two images, so that the detection robustness is increased. The ground road guide arrow only exists between the lanes, so after the detection of the lanes is completed, step S207 is performed to acquire the inter-lane region-of-interest image, mainly by scanning the middle region of the lane line, and if a white region is found, the region where the ground road guide arrow exists can be preliminarily determined. Then, step S208 is performed to extract edge information from the image in the region of interest, and step S209 calculates seven feature values by using the Hu invariant moment, performs image transformation on the set features of the image in the region of interest by using the Hu invariant moment feature values, and uses the set features as a basis for target classification. The Hu invariant moment values are then compared and classified by a similarity measure. And calculating the similarity through the March distance measurement in the step S210, matching the similarity of the images, and finally obtaining the current lane mark identified in the step S211.

The image recognition processing flow of the traffic light in the method of the invention is shown in fig. 4, because the mutual influence of the color and the illumination of the RGB color space is large, the HSV color space which is less influenced by the illumination is selected in the step S212 of the invention, the color of the image is divided, the HSV color space accords with the perception of human eyes to the color, three color channels of the HSV color space are hue H (hue), saturation S (saturation) and brightness V (value), the three components are mutually independent, and the requirements of the traffic light detection and recognition system on the independence and uniformity of the color space can be met. Then, in step S213, the image is filtered by using a circularity method, and a region with too low circularity is filtered by using circularity detection for a circular traffic light. Then, step S214 is performed to confirm the traffic light region by using the shape feature, where the traffic light has a significant feature in shape, that is, the light panel is a black rectangular frame, and the black rectangular frame has a specific length-width ratio according to the design specification of the traffic light, and the traffic light region filtered by the roundness method is confirmed again by using the feature. And step S30 is carried out to identify the color of the traffic light, the H component of the candidate area is counted by using the color histogram, and the color of the traffic light is correspondingly identified. Finally, using the matching template, step S40 is performed to identify the green light illuminated shape.

The structure of the system is shown in fig. 2, and the system comprises an image acquisition module 1, an information processing and control module 2, a distance acquisition module 3, a speed acquisition module 4 and a prompt module 5. The image acquisition module 1 is arranged at the upper end of a front windshield of a vehicle, and mainly utilizes a CMOS camera to shoot pictures at a crossing, so that other operations are convenient to carry out. The information processing and control module 2 is connected with other modules, is arranged in the vehicle center console, and is mainly used for processing and analyzing the received information, and then issuing the following instructions to the modules to control the modules. The image recognition processing including the lane and traffic lights mentioned above is all completed by the information processing and control module 2. The information processing and control module 2 judges whether traffic lights exist or not after the image acquisition module 1 acquires images, and if the traffic lights exist, the color and the shape of the traffic lights are analyzed successively; if the circular green light is judged to be lighted or the arrow-shaped green light which is lighted is judged to be matched with the lane, the information processing and control module 2 can issue a distance measuring instruction to the distance acquisition module 3. The distance acquisition module 3 is arranged at the position under the vehicle head and is mainly used for measuring the distance between a vehicle and an object in front, and the module can be a millimeter wave radar and can also be other parts for ranging. And after receiving the ranging instruction, the distance acquisition module 3 immediately performs distance measurement and feeds back the acquired result to the information processing and control module 2. If the information processing and control module 2 determines that the distance exceeds or equals to the set value, the speed acquisition module 4 is sent a speed measurement instruction after waiting for the first response time. The first reaction time is generally set to 10 seconds or less. The speed acquisition module 4 can be set as a speed sensor, can also directly acquire the speed through an instrument panel and is generally arranged in the middle of the vehicle head. After the speed acquisition module 4 performs the speed measurement operation, the data also needs to be fed back to the information processing and control module 2 again, and if the speed is zero at this time, the information processing and control module 2 sends an instruction to the prompt module 5. The prompting module 5 is arranged near the instrument panel of the vehicle.

The hardware circuit layout of the system of the present invention is disclosed below, and for clarity of description, the components used in the system of the present invention are specifically limited, but do not represent the only embodiment of the present invention.

The whole hardware circuit of the system is shown in fig. 5 and comprises an image acquisition module 1, an information processing and control module 2, a distance acquisition module 3, a speed acquisition module 4 and a prompt module 5. The image acquisition module 1 adopts a CMOS image sensing chip with the model of OV 7670; the main control chip MCU in the information processing and control module 2 adopts STM32F407ZET 6; the distance acquisition module 3 adopts an ultrasonic ranging sensor, wherein the ultrasonic sensor for transmitting and receiving signals adopts UCM-40-R piezoelectric ceramic; the speed acquisition module 4 adopts a Hall speed measurement sensor with a chip of A3144; the prompting module 5 adopts an LED lamp and a buzzer.

As shown in fig. 6, a part of circuits of the image acquisition module 1 is a circuit, because a Pixel Clock (PCLK) of the OV7670 can reach 24Mhz at most, it is very difficult to capture data directly by using an IO port of STM32F407ZET6, and it also consumes CPU, so that the data from the OV7670 is not captured directly, but read through FIFO, and the camera module of the camera module is provided with a FIFO chip for temporarily storing the image data, so that the camera module of the camera module 1 can conveniently obtain the image data without needing a single chip with high-speed IO and without consuming much CPU.

The connection relationship between each signal pin of the OV7670 chip and the MCU is as follows:

OV SDA is connected with PG 13;

OV SCL connected to PD 3;

the FIFO RCLK is connected with PB 4;

the FIFO WEN is connected with PB 3;

FIFO WRST is connected with PD 6;

the FIFO RRST is connected with PG 14;

FIFO OE is connected with PG 15;

OV VSYNC is connected with PA 8;

OV D [7:0] is connected with PC [7:0 ].

Part of the circuit of the distance acquisition module 3 is shown in fig. 7, the ultrasonic sensor comprises two pieces of UCM-40-R piezoelectric ceramics, one piece is used for transmitting signals, and a signal input port is connected with a PA1 port of the MCU; the other is used for receiving signals, and the received signals are amplified by a secondary amplifying circuit and input to a PA2 port of the MCU.

The partial circuit of the speed acquisition module 4 is shown in fig. 8, a power supply end of a hall speed measurement chip a3144 is connected with a system power supply, a grounding end is connected with a system ground, and an output end is connected with a PF0 port of the MCU.

The prompting module 5 has a part of circuits as shown in fig. 9, and the Buzzer part and a PE0 port of the MCU are connected with a Buzzer of the Buzzer through a resistor and a triode. The LED lamp part, the PF9 port of the MCU, is connected with the LED through a resistor. Furthermore, those skilled in the art will appreciate that while some embodiments described herein include some features included in other embodiments, rather than other features, combinations of features of different embodiments are meant to be within the scope of the invention and form different embodiments. For example, in the following claims, any of the claimed embodiments may be used in any combination.

As used herein, unless otherwise specified the use of the ordinal adjectives "first", "second", "third", etc., to describe a common object, merely indicate that different instances of like objects are being referred to, and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking, or in any other manner.

While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this description, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as described herein. Furthermore, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and may not have been selected to delineate or circumscribe the inventive subject matter. Accordingly, many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the appended claims. The present invention has been disclosed in an illustrative rather than a restrictive sense, and the scope of the present invention is defined by the appended claims.