A BRT trunk line green wave control method and system

Abstract

The present invention relates to a BRT trunk line green wave control method and system, the method comprising: setting an intersection decision point at an intersection exit position, setting a bus stop waiting line at a BRT station entrance position, and setting a departure decision point at a position after exiting the station; obtaining a green light phase time composition set G of the BRT driving direction at intersections along the line, investigating the average clearing time of slow-moving and motorized traffic in other directions after the green light phase of the BRT driving direction is started at the intersection, forming a calculated BRT green light phase time composition set; calculating a time set D of a vehicle from an upstream to a downstream intersection within a specified speed range, optimizing and adjusting the green light phase time G of a downstream intersection, and determining a set; standardizing the automatic driving process and operating parameters of a BRT vehicle, and when the vehicle arrives at the decision point, calculating the subsequent driving process and parameters, accurately implementing them by automatic driving, and controlling the vehicle to pass through the downstream intersection during the green light period j .

Description

Technical Field

[0001] The present invention relates to the field of automatic driving control technology, and in particular to a BRT trunk line green wave control method and system. Background Art

[0002] As a medium-capacity public transportation form in the city, the BRT system has the advantages of small investment, flexible form, convenient stations, and large transportation capacity. The main reason is that the rapid bus system runs on the same road as social vehicles and is controlled by a set of signals. It is difficult to achieve bus signal priority due to the constraints of social vehicles, resulting in frequent stops of vehicles at intersections, which greatly affects the speed and comfort of the vehicle and reduces the attractiveness of the BRT. Through the green wave control of the trunk line, the BRT signal priority problem is solved on the basis of affecting other traffic efficiency, the BRT running speed, punctuality and comfort are improved, the attractiveness of the BRT is enhanced, and it is of great significance to meet the needs of rapid and large-capacity public transportation in the city.

[0003] In order to realize the green wave of public transportation on the road, domestic and foreign scholars have proposed speed control of public transportation in recent years. However, due to the inability to accurately control the speed of vehicles based on manual driving, the actual acceleration and deceleration behaviors and the time required during the vehicle driving process are not considered, the speed control of single vehicles is mainly considered without taking into account the entire fleet, and there are safety hazards when vehicles arrive at intersections at higher speeds. These methods have not been put into practical application or the application effect is not obvious. With the development of intelligent networking, the pilot of autonomous driving in public transportation and the networking development of signal lights, by introducing public transportation autonomous driving, on the basis of coordinated interconnection of vehicles, roads and signal lights, a BRT trunk green wave model is established. The speed of the vehicle green wave reaching the intersection is dynamically calculated according to the green light time distribution of the downstream intersection, that is, the relevant formal parameters, which are accurately executed by autonomous driving. At present, BRT green waves can pass through intersections.

[0004] However, the time it takes for BRT vehicles to arrive at the next intersection often fluctuates greatly due to factors such as the uncertainty of the stop time at the station, differences in the driving behavior of drivers, and avoiding pedestrians and vehicles from other directions at intersections. It cannot be guaranteed that they can effectively capture the green light period at the next intersection. In addition, affected by intersections, BRT vehicles usually run in a convoy on the road. To achieve the green wave operation of the BRT trunk line, it is necessary to ensure that every vehicle in the convoy can pass the green wave. However, there are often large differences in the stop time and driving behavior of different vehicles at the station. The speed and headway of vehicles in the convoy are somewhat random. To ensure the green wave passage of the convoy, it is necessary to ensure a sufficient and unstable green wave bandwidth. It is even more difficult to ensure this green wave bandwidth in the green light phase, which is often only 30 to 40 seconds or even shorter. Summary of the invention

[0005] In order to ensure the green wave passage of the convoy, the purpose of the present invention is to provide a BRT trunk green wave control method and system, and the technical scheme adopted is as follows:

[0006] In a first aspect, the present application discloses a BRT trunk line green wave control method, the method comprising:

[0007] S1. Set up an intersection decision point at the exit of the intersection, a bus stop waiting line at the entrance of the BRT station, and a departure decision point after the exit;

[0008] S2. Obtain the green light phase time of the BRT driving direction at the intersection along the route Form a set G and investigate the average time it takes for slow-moving and motorized traffic in other directions to clear after the green light phase of the BRT driving direction is activated at the intersection ,based on Calculate the BRT green light phase time and form a set ;

[0009] S3, calculate the time set D of vehicles from the upstream intersection to the downstream intersection within the specified speed range, optimize and adjust the green light phase time G of the downstream intersection, and determine the set ,accomplish , and achieve The solution is maximized to form an intersection signal timing plan suitable for the green wave of the trunk line;

[0010] S4. Standardize the BRT vehicle autonomous driving process and operating parameters. When the vehicle reaches the decision point, the subsequent driving process and parameters are calculated and accurately implemented by autonomous driving.

[0011] S5. When it is determined that the vehicle has reached the intersection decision point, control the vehicle to travel according to the established parameters and pass the downstream intersection during the green light period. j .

[0012] Further, in step S3, the downstream intersection green light phase time G is optimized and adjusted, and the set ,accomplish , forming an intersection signal timing scheme suitable for the trunk green wave, including:

[0013] S31, calculate the maximum speed of the vehicle and minimum driving speed From upstream intersection i Drive to the downstream intersection j Time required 、 :

[0014] ;

[0015] ;

[0016] in, is the distance between the intersection decision point and the downstream intersection stop line, The average station time from when a BRT vehicle arrives at the waiting line at the bus station to when it completes boarding and alighting of passengers and arrives at the departure decision line;

[0017] S32. For sections with BRT stations, based on the average station time , the time set for vehicles to reach the downstream intersection according to the maximum speed and minimum speed is calculated by the following formula D :

[0018] ;

[0019] S33. For sections without BRT stations, the following formula is used to calculate the time set for vehicles to reach the downstream intersection at the maximum and minimum speeds: D :

[0020] ;

[0021] S34, repeatedly optimize and adjust G by arranging the phase sequence, optimizing the signal cycle, and optimizing the signal timing method, and form a corresponding set ,accomplish , and achieve The solution of is maximized;

[0022] S35. Repeat steps S31 to S34 to optimize and adjust the signal timing of each intersection to form an intersection signal timing plan suitable for the main line green wave.

[0023] Further, in step S4, the BRT vehicle automatic driving process and operating parameters are determined by the following steps:

[0024] S41. Determine the acceleration and deceleration parameters of the bus based on the safety and comfort of the bus acceleration and deceleration. a ;

[0025] S42. For sections without BRT stations, the standard vehicle driving process is set as follows:

[0026] When the vehicle reaches the intersection decision point, control the vehicle from the current starting speed Acceleration and deceleration a Driving time Adjust to target speed ;

[0027] Control the vehicle to the target speed Uniform forward time After approaching the downstream intersectionj ;

[0028] Control the vehicle to accelerate or decelerate a Driving time To safe speed Via downstream intersection j；

[0029] S43. For sections with BRT stations, the standardized vehicle driving process is set as follows:

[0030] When the vehicle reaches the intersection decision point, control the vehicle from the current starting speed Acceleration and deceleration a Driving time Adjust to the first target speed ;

[0031] Control the vehicle to the first target speed Uniform forward time Then approach the BRT station;

[0032] Control the vehicle to accelerate or decelerate a Driving time To parking speed Arrive at the bus stop and wait for the line to stop;

[0033] Park safely in the designated parking area at the BRT station and pick up and drop off passengers according to the BRT station conditions;

[0034] After the vehicle has completed boarding and disembarking, the vehicle starts accelerating to the station waiting speed and arrive at the departure decision point;

[0035] The actual time it takes for a vehicle to reach the departure decision point from the waiting line at the bus station , calculate the station to the downstream intersection j The second target speed between , and control the vehicle from the current waiting speed Acceleration and deceleration a Driving time Adjust to the second target speed ;

[0036] Control the vehicle to the second target speed Uniform forward time To downstream intersection j nearby;

[0037] Control the vehicle to accelerate or decelerate a Driving time To safe speed Via downstream intersection j .

[0038] Further, in step S5, when it is determined that the vehicle has reached the intersection decision point, the vehicle is controlled to travel according to the predetermined parameters and pass the downstream intersection during the green light period. j ,include:

[0039] S51. When determining that the vehicle has reached the intersection decision point, for the case where there is no BRT station on the road section, calculate the time set at which the vehicle can pass the downstream intersection with the green wave. W , combined with the safe headway between the vehicle in front of the convoy and the vehicles in between st , planning vehicles to arrive at the downstream intersection j Time , calculate the planned vehicle speed and travel time at each stage on the road section, and feedback the vehicle execution so that the vehicle can pass the downstream intersection during the green light period j ;

[0040] S52: When determining the vehicle arrival decision point at the intersection, if there is a BRT station on the road section, plan the vehicle to arrive at the downstream intersection j Time , calculate the planned vehicle speed and travel time at each stage on the road section, and provide feedback to the vehicle for execution. When it is determined that the vehicle has completed the BRT station pick-up and drop-off and arrived at the departure decision point, the vehicle speed is optimized according to the actual arrival time or reaches the downstream intersection j Time , so that vehicles can pass through the downstream intersection during the green light period j .

[0041] Further, in step S51, the vehicle is controlled to pass through the downstream intersection during the green light period. j The steps include:

[0042] S511, when the vehicle arrives at the intersection decision point, according to the vehicle arrival time ,speed , intersection spacing , safe driving speed at intersections , calculate the vehicle can pass the downstream intersection with green wave j Time , and form a set W :

[0043] ;

[0044] ;

[0045] ;

[0046] ;

[0047] in, For vehicles k From the intersection i Green wave can pass through downstream intersection j time;

[0048] S512, according to the safe headway st , planning vehicles in the fleet k Arriving at the downstream intersection j Time ,in:

[0049] when When:

[0050] ;

[0051] when When:

[0052] ;

[0053] in, To plan the vehicles in the fleet k The previous vehicle arrives at the downstream intersection j time, for j Intersection BRT n Calculate the green light phase time, for j Intersection BRT n+ 1 to calculate the green light phase time;

[0054] S513, according to the vehicles in the planned fleet k Time to reach downstream intersection , calculate the speed parameter of the vehicle's next travel and time parameters , , , which constitutes the vehicle planning driving parameter set PR :

[0055] ;

[0056] ;

[0057] ;

[0058] ;

[0059] ;

[0060] ;

[0061] S514: Driving parameter collection PR Feedback to BRT vehicles is accurately executed by autonomous driving, and the green wave is realized to reach the downstream intersection j , actual arrival time .

[0062] Further, in step S52, the vehicle is controlled to pass through the downstream intersection during the green light period. j The steps include:

[0063] S521, when the vehicle arrives at the intersection decision point, according to the arrival time ,speed ,intersection i The distance between the decision point and the waiting line of the bus station L im , bus station departure decision point to downstream intersection j Decision point distance L mj , average BRT station time , calculate the time that the vehicle can pass the downstream intersection with the green wave , forming a set W :

[0064] ;

[0065] S522, according to the safe headway st , planning vehicles in the fleet k Arriving at the downstream intersection j Time ,in:

[0066] when When:

[0067] ;

[0068] when When:

[0069] ;

[0070] S523, according to the vehicles in the planned fleet k Arriving at the downstream intersection j Time , average BRT station time , calculate the speed parameter of the vehicle's next travel , , time parameters , , Composition of vehicle planning driving parameter set PR :

[0071] ;

[0072] ;

[0073] ;

[0074] ;

[0075] ;

[0076] ;

[0077] ;

[0078] ;

[0079] ;

[0080] ;

[0081] in, For vehicles at the bus station m The waiting speed of the waiting line is convenient for users to wait at the bus stop or choose a suitable parking space; The waiting speed is the speed at which the vehicle starts to drive slowly to the departure decision point after completing boarding and alighting of passengers at the bus stop.

[0082] S524: Driving parameter collection PR Feedback to BRT vehicles is accurately executed by autonomous driving. When the vehicle completes the pick-up and drop-off at the bus stop and arrives at the departure decision point, it is determined whether it arrives according to the established planned time, that is, the actual arrival time = Is it true? If true, follow the planned driving parameters Continue the operation and achieve green wave to downstream intersection j The actual arrival time is If not, proceed to steps S525-S527 to optimize and adjust the subsequent driving parameters so that it passes the downstream intersection during the green light time;

[0083] S525. According to the actual arrival time of the vehicle at the departure decision point , recalculate the vehicle's green wave to pass the downstream intersection j Time , forming a set :

[0084] ;

[0085] in, For vehicles at bus stops mAfter completing boarding and disembarking, the vehicle starts to drive slowly to the waiting speed at the departure decision point. For adjusted vehicles from the bus station m Accelerate to the new target speed The acceleration time, To adjust the vehicle The time of constant speed driving, For vehicles from Slow down to a safe speed at the intersection time, It is the travel time of the vehicle from the departure decision point to the stop line of the downstream intersection;

[0086] S526, according to the safe headway st , adjust the vehicle k Arriving at the downstream intersection j Time ,in:

[0087] when When:

[0088] ;

[0089] when When:

[0090] ;

[0091] in, For vehicles k The previous vehicle arrives at the downstream intersection j time;

[0092] S527, according to the vehicle k Adjusted time to reach downstream intersection , calculate the speed parameter of the vehicle's next travel , time parameters , and feedback that the vehicle is accurately executed by autonomous driving, so that its green wave reaches the downstream intersection j The actual arrival time is :

[0093] ;

[0094] ;

[0095] ;

[0096] ;

[0097] ;

[0098] in, It is the target speed of the vehicle in the road section after adjustment.

[0099] In the second aspect, the present application also discloses a BRT trunk green wave control system, the system comprising a decision point setting module, a green light phase analysis module, a trunk green wave optimization module, an automatic driving process standardization module, and a green light passage control module, wherein:

[0100] The decision point setting module is used to set the intersection decision point at the intersection exit, set the bus stop waiting line at the BRT station entrance, and set the departure decision point at the exit;

[0101] The green light phase analysis module is used to obtain the green light phase time of the BRT driving direction along the intersection Form a set G and investigate the average time it takes for slow-moving and motorized traffic in other directions to clear after the green light phase of the BRT driving direction is activated at the intersection ,based on Calculate the BRT green light phase time and form a set ;

[0102] The trunk green wave optimization module is used to calculate the time set D of vehicles from the upstream intersection to the downstream intersection within the specified speed range, optimize and adjust the green light phase time G of the downstream intersection, and determine the set ,accomplish , and achieve The solution is maximized to form an intersection signal timing plan suitable for the green wave of the trunk line;

[0103] The autonomous driving process standardization module is used to standardize the autonomous driving process and operating parameters of BRT vehicles. When the vehicle reaches the decision point, the subsequent driving process and parameters are calculated and accurately implemented by autonomous driving;

[0104] The green light control module is used to control the vehicle to travel according to the established parameters and pass the downstream intersection during the green light period when it is determined that the vehicle has reached the intersection decision point. j .

[0105] In a third aspect, the present application further discloses a computer-readable storage medium storing a computer program, characterized in that when the computer program is executed by a processor, the BRT trunk green wave control method is implemented.

[0106] In a fourth aspect, the present application also discloses a BRT trunk green wave control device, characterized in that it includes a communication interface, a memory, a communication bus and a processor, wherein the processor, the communication interface and the memory communicate with each other through the communication bus;

[0107] The memory is used to store computer programs;

[0108] The processor is used to implement the steps of the BRT trunk green wave control method when executing the program stored in the memory.

[0109] The present invention has the following beneficial effects:

[0110] 1. By precisely controlling the driving behavior and speed of vehicles throughout the entire process, the driving time between intersections can be dynamically regulated, solving the problem of vehicles driving freely and arriving at intersections uncontrollably without any regulatory measures. This allows the green wave to reach the downstream intersection under the established signal control scheme, reducing the number of vehicle stops and improving BRT speed and efficiency.

[0111] 2. Green wave passage can be achieved by adjusting the vehicle's own driving behavior, without giving priority to special signals, so as to avoid affecting the efficiency of other traffic operations outside the dedicated lane.

[0112] 3. By planning the arrival time and related parameters of each vehicle at the intersection, the green wave traffic of the entire fleet is considered in a coordinated manner rather than a single vehicle, so as to achieve overall speed and efficiency improvement of the BRT system.

[0113] 4. Taking advantage of the relatively low traffic density on the BRT lanes and the generally surplus lane capacity, the green light phase time is appropriately sacrificed as intersection clearing time to form a BRT green light phase, which reduces the probability of BRT vehicles being forced to stop at intersections to avoid other traffic, and improves the speed and safety of BRT vehicles passing through intersections. BRIEF DESCRIPTION OF THE DRAWINGS

[0114] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0115] Figure 1 A method flow chart of a BRT trunk green wave control method provided by an embodiment of the present invention;

[0116] Figure 2 Set up schematic diagrams for intersection decision points;

[0117] Figure 3 This is a schematic diagram of green wave control for BRT trunk lines;

[0118] Figure 4 A standardized schematic diagram of BRT vehicle driving process and parameters;

[0119] Figure 5 A system structure diagram of a BRT trunk green wave control system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0120] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following is a detailed description of a BRT trunk green wave control method and system proposed according to the present invention, its specific implementation method, structure, features and effects, in combination with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0121] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0122] The specific scheme of a BRT trunk green wave control method and system provided by the present invention is described in detail below with reference to the accompanying drawings.

[0123] See also Figure 1 , which shows a method flow chart of a BRT trunk green wave control method provided by an embodiment of the present invention, the method comprising the following steps:

[0124] Step S1, setting an intersection decision point at the intersection exit, setting a bus stop waiting line at the BRT station entrance, and setting a departure decision point at the exit.

[0125] Specifically, although the position information of vehicles on the road can be dynamically obtained in a vehicle-road cooperative environment, considering that the positioning information usually has a certain error, in order to improve the accuracy of regulation, this application considers setting an intersection decision point after passing the sidewalk at the intersection exit, setting a departure decision point after exiting the BRT station, and setting a bus stop waiting line at the entrance of the BRT station, such as Figure 2 shown.

[0126] Furthermore, the present application also measures the distance between the above-mentioned intersection decision point and the BRT station L im , the distance from the departure decision point to the downstream intersection L mj , and the distance between the intersection decision point and the downstream intersection stop line L ij .

[0127] Step S2: Obtain the green light phase time of the BRT driving direction at the intersection along the route Form a set G and investigate the average time it takes for slow-moving and motorized traffic in other directions to clear after the green light phase of the BRT driving direction is activated at the intersection ,based on Calculate the BRT green light phase time and form a set .

[0128] Specifically, although BRT vehicles can pass through intersections after the green light phase of the intersection is started, if a vehicle arrives at the intersection when the green light phase has just started and pedestrians and traffic in other directions have not yet been completely cleared, it may be forced to stop because it needs to avoid other traffic. To avoid this phenomenon, this application considers appropriately sacrificing the green light phase time as the intersection clearing time based on the actual situation that the traffic density on the BRT lane is relatively low and the lane capacity is generally surplus, forming a BRT calculation green light phase, which is delayed from the start of the green light phase of the intersection.

[0129] Step S3, calculate the time set D of the vehicle from the upstream intersection to the downstream intersection within the specified speed range, optimize and adjust the green light phase time G of the downstream intersection, and determine the set ,accomplish , and achieve It is maximized to form an intersection signal timing plan suitable for the main line green wave.

[0130] Specifically, for road sections that have not considered green wave traffic before the implementation of this application, it is necessary to first optimize the intersection traffic lights according to the green wave traffic requirements so as not to affect the driving of other vehicles and form an intersection signal timing plan suitable for the main green wave.

[0131] Step S4, standardizes the BRT vehicle automatic driving process and operating parameters. When the vehicle reaches the decision point, the subsequent driving process and parameters are calculated and accurately implemented by automatic driving.

[0132] For details, please refer to Figure 3 and Figure 4 ,This application standardizes the driving process and operating parameters of the vehicles based on the situations and responses that BRT vehicles may encounter when traveling on the road sections, facilitating unified and process-based control and management based on autonomous driving.

[0133] Step S5: When it is determined that the vehicle has reached the intersection decision point, the vehicle is controlled to travel according to the established parameters and pass the downstream intersection during the green light period. j .

[0134] As can be seen from the above, the BRT trunk green wave control method disclosed in the present application sets intersection decision points and departure decision points at the intersection exit and the bus station exit, and performs dynamic control after the vehicle leaves the intersection and bus station, thereby avoiding the uncertainty of the vehicle's driving or parking time at the intersection and bus station; at the same time, the distance between the decision point and the bus station and the downstream intersection is measured, which improves the accuracy of the distance when calculating the control speed and related parameters. By investigating the average clearing time of slow-moving and motorized traffic in other directions after the green light phase of the intersection is started, and taking advantage of the relatively low traffic density on the BRT lane and the generally surplus lane capacity, part of the green light phase time is appropriately sacrificed as the intersection clearing time, forming the BRT calculated green light phase, reducing the probability of BRT vehicles being forced to stop at the intersection to avoid other traffic, and improving safety. By standardizing the BRT vehicle automatic driving process and operating parameters, unified and process-based control and management of vehicle driving behavior can be achieved on the basis of automatic driving, ensuring that vehicles arrive at downstream intersections on time according to the established speed and other related parameter plans, solving the problem that the time to arrive at the intersection is uncontrollable under the current manual driving and free driving without control measures. By calculating and planning driving behavior parameters at the intersection decision point, and further optimizing the next driving behavior parameters according to the actual stop time after completing the bus stop and arriving at the departure decision point, the problem of vehicle stop uncertainty at the bus stop is solved, and the green wave is achieved to reach the downstream intersection. By combining the fleet following vehicles, the safe head distance of vehicles and the green light phase of the downstream intersection, the time and related parameters of each vehicle arriving at the intersection are planned, and the green wave passage of the entire fleet is considered in a comprehensive manner, rather than a single vehicle, to achieve overall speed and efficiency improvement of the BRT system. The whole process does not need to give priority to special signals to avoid affecting the efficiency of other traffic operations outside the dedicated lanes.

[0135] In one embodiment, in step S3, the downstream intersection green light phase time G is optimized and adjusted, and the set ,accomplish , and achieve Maximize it and form an intersection signal timing plan suitable for the main line green wave, including:

[0136] Step S31, calculating the maximum speed of the vehicle and minimum driving speed From upstream intersection i Drive to the downstream intersection j Time required 、 :

[0137] ;

[0138] ;

[0139] in, is the distance between the intersection decision point and the downstream intersection stop line, It is the average stop time from when a BRT vehicle enters the waiting line of a bus station to when it reaches the departure decision line.

[0140] Step S32: For sections with BRT stations, the average station time , the time set D of vehicles arriving at the downstream intersection at the maximum speed and the minimum speed is calculated by the following formula:

[0141] .

[0142] Step S33: For a section without a BRT station, the time set D for a vehicle to reach the downstream intersection at the maximum speed and the minimum speed is calculated by the following formula:

[0143] .

[0144] Step S34, repeatedly optimizing and adjusting G by arranging the phase sequence, optimizing the signal cycle, and optimizing the signal timing method, and forming a corresponding set ,accomplish , and achieve The solution of maximization.

[0145] Step S35, repeating steps S31 to S34, optimizing and adjusting the signal timing of each intersection, and forming an intersection signal timing plan suitable for the trunk green wave.

[0146] In one embodiment, in step S4, the BRT vehicle automatic driving process and operating parameters are determined by the following steps:

[0147] Step S41, based on the safety and comfort of bus acceleration and deceleration, determine the vehicle driving acceleration and deceleration parameters a .

[0148] Step S42, please refer to Figure 3 For sections without BRT stations, the standard vehicle driving process is set as follows:

[0149] When the vehicle reaches the intersection decision point, control the vehicle from the current starting speed Acceleration and deceleration a Driving time Adjust to target speed ;

[0150] Control the vehicle to the target speed Uniform forward time After approaching the downstream intersection j ;

[0151] Control the vehicle to accelerate or decelerate a Driving time To safe speed Via downstream intersection j .

[0152] Specifically, generally speaking, if a BRT vehicle passes through an intersection too fast, it is easy to cause a safety accident, and if it passes through an intersection too slowly, it will affect the efficiency of the intersection. According to the road traffic management regulations and the driving characteristics of the BRT itself, it is necessary to determine the safe speed of the autonomous vehicle passing through the road intersection. , ensuring the safety and efficiency of vehicles passing through intersections.

[0153] Step S43, please refer to Figure 3 For sections with BRT stations, the standardized vehicle driving process is set as follows:

[0154] When the vehicle reaches the intersection decision point, control the vehicle from the current starting speed Acceleration and deceleration a Driving time Adjust to the first target speed ;

[0155] Control the vehicle to the first target speed Uniform forward time Then approach the BRT station;

[0156] Control the vehicle to accelerate or decelerate a Driving time To parking speed Arrive at the bus stop and wait for the line to stop;

[0157] Park safely in the designated parking area at the BRT station and pick up and drop off passengers according to the BRT station conditions;

[0158] After the vehicle has completed boarding and disembarking, the vehicle starts accelerating to the station waiting speed and arrive at the departure decision point;

[0159] The actual time it takes for a vehicle to reach the departure decision point from the waiting line at the bus station , calculate the station to the downstream intersection j The second target speed between , and control the vehicle from the current waiting speed Acceleration and deceleration a Driving time Adjust to the second target speed ;

[0160] Control the vehicle to the second target speed Uniform forward time To downstream intersection jnearby;

[0161] Control the vehicle to accelerate or decelerate a Driving time To safe speed Through the downstream intersection j .

[0162] It should be noted that the time from the waiting line of the bus station to the departure decision line is called the station time. .

[0163] Specifically, when the BRT slows down and stops at a station, there are often passengers who are about to get off and stand or walk towards the door before the vehicle is stable. If the vehicle needs to slow down and stop at a higher speed at this time, the deceleration will often be too large, causing the passengers to stand unstable. Therefore, it is necessary to determine the safe speed of the autonomous vehicle to arrive at the station waiting line , so that the vehicle arrives at the station at a lower starting speed and slows down to stop, ensuring the safety and comfort of passengers. At the same time, when the vehicle is ready to get on and off, there are often some passengers who have not yet taken their seats or stood firmly in a suitable position. Therefore, it is necessary to determine that the autonomous driving vehicle drives a certain distance at a lower safe speed to the departure decision point, so that passengers can sit and stand firmly during this period.

[0164] In one embodiment, in step S5, when it is determined that the vehicle has reached the intersection decision point, the vehicle is controlled to travel according to the predetermined parameters and pass the downstream intersection during the green light period. j ,include:

[0165] Step S51: when it is determined that the vehicle has reached the intersection decision point, for the case where there is no BRT station on the road section, calculate the time set at which the vehicle can pass the downstream intersection with the green wave W , combined with the safe headway between the vehicle in front of the convoy and the vehicles in between st, Plan vehicles to arrive at downstream intersections j Time , calculate the planned vehicle speed and travel time at each stage on the road section, and feedback the vehicle execution so that the vehicle can pass the downstream intersection during the green light period j .

[0166] Specifically, generally speaking, each BRT vehicle can reach the downstream intersection at different green light time points through multiple speed schemes. It is necessary to consider that multiple vehicles may enter the road section in the same signal cycle to form a convoy and drive to the downstream intersection. In order to ensure that all convoy vehicles can pass the downstream intersection with a green wave, this application combines the convoy safety headway time st Comprehensively plan the time for each vehicle to arrive at the downstream intersection , and calculate the vehicle's next speed and time parameters to feed back the vehicle for precise execution, allowing the vehicle to pass the downstream intersection during the green light period j .

[0167] Compared with the existing traditional signal control scheme based on manual driving, this application is based on automatic driving and can accurately control the acceleration, speed and driving time of the vehicle to ensure that it arrives at the intersection according to the established plan, improve the green wave traffic realization rate, thereby improving the average travel speed, operating efficiency and punctuality of BRT vehicles, and effectively reducing the number of stops and parking delays of BRT vehicles.

[0168] Step S52: when the vehicle reaches the intersection decision point, if there is a BRT station on the road section, plan the vehicle to reach the downstream intersection. j Time , calculate the planned vehicle speed and travel time at each stage on the road section, and provide feedback to the vehicle for execution. When it is determined that the vehicle has completed the BRT station pick-up and drop-off and arrived at the departure decision point, the vehicle speed is optimized according to the actual arrival time or reaches the downstream intersection j Time , so that vehicles can pass through the downstream intersection during the green light period j .

[0169] Specifically, the BRT vehicle's stop time at a BRT station is usually uncertain. In actual operation, it is sometimes unable to complete boarding and alighting and arrive at the departure decision point at the scheduled time. Therefore, it is necessary to optimize the planning or speed to reach the downstream intersection based on the actual time the vehicle arrives at the departure decision point. j Time , ensuring that vehicles pass through downstream intersections during green light periods j。

[0170] In one embodiment, in step S51, the vehicle is controlled to pass through the downstream intersection during the green light period. j The steps include:

[0171] Step S511: When a vehicle arrives at a decision point at an intersection, the vehicle ,speed , intersection spacing , safe driving speed at intersections , calculate the vehicle can pass the downstream intersection with green wave j Time , and form a set W :

[0172] ;

[0173] ;

[0174] ;

[0175] ;

[0176] in, For vehicles k From the intersection i Green wave can pass through downstream intersection j time.

[0177] Step S512, based on the safety headway st , planning vehicles in the fleet k Arriving at the downstream intersection j Time ,in:

[0178] when When:

[0179] ;

[0180] when When:

[0181] ;

[0182] in, To plan the vehicles in the fleet k The previous vehicle arrives at the downstream intersection j time, for j Intersection BRT n Calculate the green light phase time, for j Intersection BRT n+ 1 Calculate the green light phase time.

[0183] Specifically, affected by intersections, BRT vehicles usually run in convoys on the road, that is, multiple vehicles pass through the intersection at the same green light period, and leave a clear time and distance interval with the vehicles passing through the next green light period at the intersection, forming a temporary convoy on the road section between the intersection and the downstream intersection. To achieve green wave operation of the BRT trunk line, it is necessary to ensure that each vehicle in the temporary convoy can pass the next intersection with a green wave. However, there are often large differences in the stop time and driving behavior of different vehicles at stations, and the speed and headway of vehicles in the temporary convoy have a certain degree of randomness. In order to ensure the green wave passage of the temporary convoy, this application comprehensively plans and arranges the time for the vehicle to arrive at the downstream intersection according to the specific time of the vehicle arriving at the intersection decision point and the safe vehicle distance.

[0184] Step S513: according to the vehicles in the planned fleet k Time to reach downstream intersection , calculate the speed parameter of the vehicle's next travel and time parameters , which constitutes the vehicle planning driving parameter set PR :

[0185] ;

[0186] ;

[0187] ;

[0188] ;

[0189] ;

[0190] ;

[0191] Step S514: Set the driving parameters PR Feedback to BRT vehicles is accurately executed by autonomous driving, and the green wave is realized to reach the downstream intersection j , actual arrival time .

[0192] In one embodiment, in step S52, the vehicle is controlled to pass through the downstream intersection during the green light period. j The steps include:

[0193] Step S521: When the vehicle arrives at the intersection decision point, according to the arrival time ,speed ,intersection i The distance between the decision point and the waiting line of the bus station L im , bus station departure decision point to downstream intersection j Decision point distance L mj , average BRT station time , calculate the time that the vehicle can pass the downstream intersection with the green wave , forming a set W :

[0194] ;

[0195] Step S522, based on the safe headway time st , planning vehicles in the fleet k Arriving at the downstream intersection j Time ,in:

[0196] when When:

[0197] ;

[0198] when When:

[0199] .

[0200] Step S523: according to the vehicles in the planned fleet k Arriving at the downstream intersection j Time , average BRT station time , calculate the speed parameter of the vehicle's next travel , time parameters , Composition of vehicle planning driving parameter set PR :

[0201] ;

[0202] ;

[0203] ;

[0204] ;

[0205] ;

[0206] ;

[0207] ;

[0208] ;

[0209] ;

[0210] ;

[0211] in, For vehicles at the bus station m The waiting speed of the waiting line is convenient for users to wait at the bus stop or choose a suitable parking space; The waiting speed is the speed at which the vehicle starts to drive slowly to the departure decision point after completing boarding and alighting of passengers at the bus stop.

[0212] Step S524, driving parameter set PR Feedback to BRT vehicles is accurately executed by autonomous driving. When the vehicle completes the pick-up and drop-off at the bus stop and arrives at the departure decision point, it is determined whether it arrives according to the established planned time, that is, the actual arrival time = Is it true? If true, follow the planned driving parameters Continue the operation and achieve green wave to downstream intersection j The actual arrival time is If not, then proceed to steps S525 to S527 to optimize and adjust the subsequent driving parameters so that the driver can pass the downstream intersection within the green light time;

[0213] Step S525: according to the actual time when the vehicle arrives at the departure decision point , recalculate the vehicle's green wave to pass the downstream intersection j Time , forming a set :

[0214]

[0215] in, For vehicles at bus stops m After completing boarding and disembarking, the vehicle starts to drive slowly to the waiting speed at the departure decision point. For adjusted vehicles from the bus station m Accelerate to the new target speed The acceleration time, To adjust the vehicle The time of constant speed driving, For vehicles from Slow down to a safe speed at the intersection time, It is the travel time of the vehicle from the departure decision point to the stop line of the downstream intersection;

[0216] Step S526, based on the safe headway st , adjust the vehicle k Arriving at the downstream intersection j Time ,in:

[0217] when When:

[0218] ;

[0219] when When:

[0220] ;

[0221] in, For vehicles k The previous vehicle arrives at the downstream intersection j time.

[0222] Step S527, according to the vehicle k Adjusted time to reach downstream intersection , calculate the speed parameter of the vehicle's next travel , time parameters , and feedback that the vehicle is accurately executed by autonomous driving, so that its green wave reaches the downstream intersection j The actual arrival time is :

[0223] ;

[0224] ;

[0225] ;

[0226] ;

[0227] ;

[0228] in, It is the target speed of the vehicle in the road section after adjustment.

[0229] Please refer to Figure 5 The present application also discloses a BRT trunk green wave control system, which includes a decision point setting module, a green light phase analysis module, a trunk green wave optimization module, an automatic driving process standardization module, and a green light passage control module, wherein:

[0230] The decision point setting module is used to set the intersection decision point at the intersection exit, set the bus stop waiting line at the BRT station entrance, and set the departure decision point at the exit;

[0231] The green light phase analysis module is used to obtain the green light phase time of the BRT driving direction along the intersection Form a set G and investigate the average time it takes for slow-moving and motorized traffic in other directions to clear after the green light phase of the BRT driving direction is activated at the intersection ,based on Calculate the BRT green light phase time and form a set ;

[0232] The trunk green wave optimization module is used to calculate the time set D of vehicles from the upstream intersection to the downstream intersection within the specified speed range, optimize and adjust the green light phase time G of the downstream intersection, and determine the set ,accomplish , and achieve The solution is maximized to form an intersection signal timing plan suitable for the green wave of the trunk line;

[0233] The autonomous driving process standardization module is used to standardize the autonomous driving process and operating parameters of BRT vehicles. When the vehicle reaches the decision point, the subsequent driving process and parameters are calculated and accurately implemented by autonomous driving;

[0234] The green light control module is used to control the vehicle to travel according to the established parameters and pass the downstream intersection during the green light period when it is determined that the vehicle has reached the intersection decision point. j .

[0235] In one embodiment, the above modules are also used to implement the steps illustrated in any of the above method embodiments, which is not limited in this application.

[0236] As can be seen from the above, the BRT trunk green wave control system disclosed in the present application sets intersection decision points and departure decision points at the intersection exit and the bus station exit, and performs dynamic control after the vehicle leaves the intersection and bus station, thereby avoiding the uncertainty of the vehicle's driving or parking time at the intersection and bus station; at the same time, the distance between the decision point and the bus station and the downstream intersection is measured, which improves the accuracy of the distance when calculating the control speed and related parameters. By investigating the average clearing time of slow-moving and motorized traffic in other directions after the green light phase of the intersection is started, and taking advantage of the relatively low traffic density on the BRT lane and the generally surplus lane capacity, part of the green light phase time is appropriately sacrificed as the intersection clearing time, forming the BRT calculated green light phase, reducing the probability of BRT vehicles being forced to stop at the intersection to avoid other traffic, and improving safety. By standardizing the BRT vehicle automatic driving process and operating parameters, unified and process-based control and management of vehicle driving behavior can be achieved on the basis of automatic driving, ensuring that vehicles arrive at downstream intersections on time according to the established speed and other related parameter plans, solving the problem that the time to arrive at the intersection is uncontrollable under the current manual driving and free driving without control measures. By calculating and planning driving behavior parameters at the intersection decision point, and further optimizing the next driving behavior parameters according to the actual stop time after completing the bus stop and arriving at the departure decision point, the problem of vehicle stop uncertainty at the bus stop is solved, and the green wave is achieved to reach the downstream intersection. By combining the fleet following vehicles, the safe head distance of vehicles and the green light phase of the downstream intersection, the time and related parameters of each vehicle arriving at the intersection are planned, and the green wave passage of the entire fleet is considered in a comprehensive manner, rather than a single vehicle, to achieve overall speed and efficiency improvement of the BRT system. The whole process does not need to give priority to special signals to avoid affecting the efficiency of other traffic operations outside the dedicated lanes.

[0237] The present application also discloses a computer-readable storage medium storing a computer program, and when the computer program is executed by a processor, the BRT trunk green wave control method is implemented.

[0238] The present application also discloses a BRT trunk green wave control device, comprising a communication interface, a memory, a communication bus and a processor, wherein the processor, the communication interface and the memory communicate with each other through the communication bus;

[0239] The memory is used to store computer programs;

[0240] The processor is used to implement the steps of the BRT trunk green wave control method when executing the program stored in the memory.

[0241] It should be noted that the sequence of the above embodiments of the present invention is only for description and does not represent the advantages and disadvantages of the embodiments. The processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0242] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A BRT trunk line green wave control method, characterized in that: The method comprises: S1. Set up an intersection decision point at the exit of the intersection, a bus stop waiting line at the entrance of the BRT station, and a departure decision point after the exit; S2. Obtain the green light phase time of the BRT driving direction at the intersection along the route Form a set G and investigate the average time it takes for slow-moving and motorized traffic in other directions to clear after the green light phase of the BRT driving direction is activated at the intersection ,based on Calculate the BRT green light phase time and form a set ; S3, calculate the time set D of vehicles from the upstream intersection to the downstream intersection within the specified speed range, optimize and adjust the green light phase time G of the downstream intersection, and determine the set ,accomplish , and achieve The solution is maximized to form an intersection signal timing plan suitable for the green wave of the trunk line; S4. Standardize the BRT vehicle autonomous driving process and operating parameters. When the vehicle reaches the decision point, the subsequent driving process and parameters are calculated and accurately implemented by autonomous driving. S5. When it is determined that the vehicle has reached the intersection decision point, control the vehicle to travel according to the established parameters and pass the downstream intersection during the green light period. j .

2. The method according to claim 1, characterized in that In step S3, the downstream intersection green light phase time G is optimized and adjusted, and the set ,accomplish , forming an intersection signal timing scheme suitable for the trunk green wave, including: S31, calculate the maximum speed of the vehicle and minimum driving speed From upstream intersection i Drive to the downstream intersection j Time required : ； ； in, is the distance between the intersection decision point and the downstream intersection stop line, The average station time from when a BRT vehicle arrives at the waiting line at the bus station to when it completes boarding and alighting of passengers and arrives at the departure decision line; S32. For sections with BRT stations, based on the average station time , the time set for vehicles to reach the downstream intersection according to the maximum speed and minimum speed is calculated by the following formula D : ； S33. For sections without BRT stations, the following formula is used to calculate the time set for vehicles to reach the downstream intersection at the maximum and minimum speeds: D : ； S34, repeatedly optimize and adjust G by arranging the phase sequence, optimizing the signal cycle, and optimizing the signal timing method, and form a corresponding set ,accomplish ,and The solution of is maximized; S35. Repeat steps S31 to S34 to optimize and adjust the signal timing of each intersection to form an intersection signal timing plan suitable for the main line green wave.

3. The method according to claim 1, characterized in that In step S4, the BRT vehicle automatic driving process and operating parameters are determined by the following steps: S41. Determine the acceleration and deceleration parameters of the bus based on the safety and comfort of the bus acceleration and deceleration. a ; S42. For sections without BRT stations, the standard vehicle driving process is set as follows: When the vehicle reaches the intersection decision point, control the vehicle from the current starting speed Acceleration and deceleration a Driving time Adjust to target speed ; Control the vehicle to the target speed Uniform forward time After approaching the downstream intersection j ; Control the vehicle to accelerate or decelerate a Driving time To safe speed Via downstream intersection j； S43. For sections with BRT stations, the standardized vehicle driving process is set as follows: When the vehicle reaches the intersection decision point, control the vehicle from the current starting speed Acceleration and deceleration a Driving time Adjust to the first target speed ; Control the vehicle to the first target speed Uniform forward time Then approach the BRT station; Control the vehicle to accelerate or decelerate a Driving time To parking speed Arrive at the bus stop and wait for the line to stop; Park safely in the designated parking area at the BRT station and pick up and drop off passengers according to the BRT station conditions; After the vehicle has completed boarding and disembarking, the vehicle starts accelerating to the station waiting speed and arrive at the departure decision point; The actual time it takes for a vehicle to reach the departure decision point from the waiting line at the bus station , calculate the station to the downstream intersection j The second target speed between , and control the vehicle from the current waiting speed Acceleration and deceleration a Driving time Adjust to the second target speed ; Control the vehicle to the second target speed Uniform forward time To downstream intersection j nearby; Control the vehicle to accelerate or decelerate a Driving time To safe speed Via downstream intersection j .

4. The method according to claim 3, characterized in that In step S5, when it is determined that the vehicle has reached the intersection decision point, the vehicle is controlled to travel according to the predetermined parameters and pass the downstream intersection during the green light period. j ,include: S51. When determining that the vehicle has reached the intersection decision point, for the case where there is no BRT station on the road section, calculate the time set at which the vehicle can pass the downstream intersection with the green wave. W , combined with the safe headway between the vehicle in front of the convoy and the vehicles in between st , planning vehicles to arrive at the downstream intersection j Time , calculate the planned vehicle speed and travel time at each stage on the road section, and feedback the vehicle execution so that the vehicle can pass the downstream intersection during the green light period j ; S52: When determining the vehicle arrival decision point at the intersection, if there is a BRT station on the road section, plan the vehicle to arrive at the downstream intersection j Time , calculate the planned vehicle speed and travel time at each stage on the road section, and provide feedback to the vehicle for execution. When it is determined that the vehicle has completed the BRT station pick-up and drop-off and arrived at the departure decision point, the vehicle speed is optimized according to the actual arrival time or reaches the downstream intersection j Time , so that vehicles can pass through the downstream intersection during the green light period j .

5. The method according to claim 4, characterized in that In step S51, the vehicle is controlled to pass through the downstream intersection during the green light period. j The steps include: S511, when the vehicle arrives at the intersection decision point, according to the vehicle arrival time ,speed , intersection spacing , safe driving speed at intersections , calculate the vehicle can pass the downstream intersection with green wave j Time , and form a set W : ； ； ； ； in, For vehicles k From the intersection i Green wave can pass through downstream intersection j time; S512, according to the safe headway st , planning vehicles in the fleet k Arriving at the downstream intersection j Time ,in: when When: ； when When: ； in, To plan the vehicles in the fleet k The previous vehicle arrives at the downstream intersection j time, for j Intersection BRT n Calculate the green light phase time, for j Intersection BRT n+ 1 to calculate the green light phase time; S513, according to the vehicles in the planned fleet k Time to reach downstream intersection , calculate the speed parameter of the vehicle's next travel and time parameters , , , which constitutes the vehicle planning driving parameter set PR : ； ； ； ； ； ； S514: Driving parameter collection PR Feedback to BRT vehicles is accurately executed by autonomous driving, and the green wave is realized to reach the downstream intersection j , actual arrival time .

6. The method according to claim 5, characterized in that In step S52, the vehicle is controlled to pass through the downstream intersection during the green light period. j The steps include: S521, when the vehicle arrives at the intersection decision point, according to the arrival time ,speed ,intersection i The distance between the decision point and the waiting line of the bus station L im , bus station departure decision point to downstream intersection j Decision point distance L mj , average BRT station time , calculate the time that vehicles can pass the downstream intersection with green wave , forming a set W : ； S522, according to the safe headway st , planning vehicles in the fleet k Arriving at the downstream intersection j Time ,in: when When: ； when When: ； S523, according to the vehicles in the planned fleet k Arriving at the downstream intersection j Time , average BRT station time , calculate the speed parameter of the vehicle's next travel , , time parameters , , , , , Composition of vehicle planning driving parameter set PR : ； ； ； ； ； ； ； ； ； ； in, For vehicles at the bus station m The waiting speed of the waiting line is convenient for users to wait at the bus stop or choose a suitable parking space; The waiting speed is the speed at which the vehicle starts to drive slowly to the departure decision point after completing boarding and alighting at the bus stop. S524: Driving parameter collection PR Feedback to BRT vehicles is accurately executed by autonomous driving. When the vehicle completes the pick-up and drop-off at the bus stop and arrives at the departure decision point, it is determined whether it arrives according to the planned time, that is, the actual arrival time. Is it true? If true, follow the planned driving parameters Continue the operation and achieve green wave to downstream intersection j The actual arrival time is If not, then proceed to steps S525 to S527 to optimize and adjust the subsequent driving parameters so that the driver can pass the downstream intersection within the green light time; S525. According to the actual arrival time of the vehicle at the departure decision point , recalculate the vehicle's green wave to pass the downstream intersection j Time , forming a set : ； in, For vehicles at bus stops m After completing boarding and disembarking, the vehicle starts to drive slowly to the waiting speed at the departure decision point. For adjusted vehicles from the bus station m Accelerate to the new target speed The acceleration time, To adjust the vehicle The time of constant speed driving, For vehicles from Slow down to a safe speed at the intersection time, It is the travel time of the vehicle from the departure decision point to the stop line of the downstream intersection; S526, according to the safe headway st , adjust the vehicle k Arriving at the downstream intersection j Time ,in: when When: ； when When: ； in, For vehicles k The previous vehicle arrives at the downstream intersection j time; S527, according to the vehicle k Adjusted time to reach downstream intersection , calculate the speed parameter of the vehicle's next travel , time parameters , , , and feedback that the vehicle is accurately executed by autonomous driving, so that its green wave reaches the downstream intersection j The actual arrival time is : ； ； ； ； ； in, It is the target speed of the vehicle in the road section after adjustment.

7. A BRT trunk green wave control system, characterized in that: The system includes a decision point setting module, a green light phase analysis module, a trunk green wave optimization module, an automatic driving process standardization module, and a green light passage control module, wherein: The decision point setting module is used to set the intersection decision point at the intersection exit, set the bus stop waiting line at the BRT station entrance, and set the departure decision point at the exit; The green light phase analysis module is used to obtain the green light phase time of the BRT driving direction along the intersection Form a set G and investigate the average time it takes for slow-moving and motorized traffic in other directions to clear after the green light phase of the BRT driving direction is activated at the intersection ,based on Calculate the BRT green light phase time and form a set ; The trunk green wave optimization module is used to calculate the time set D of vehicles from the upstream intersection to the downstream intersection within the specified speed range, optimize and adjust the green light phase time G of the downstream intersection, and determine the set ,accomplish , and achieve The solution is maximized to form an intersection signal timing plan suitable for the green wave of the trunk line; The autonomous driving process standardization module is used to standardize the autonomous driving process and operating parameters of BRT vehicles. When the vehicle reaches the decision point, the subsequent driving process and parameters are calculated and accurately implemented by autonomous driving; The green light control module is used to control the vehicle to travel according to the established parameters and pass the downstream intersection during the green light period when it is determined that the vehicle has reached the intersection decision point. j .

8. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the BRT trunk green wave control method described in any one of claims 1-6 is implemented.

9. A BRT trunk green wave control device, characterized in that: It includes a communication interface, a memory, a communication bus and a processor, wherein the processor, the communication interface and the memory communicate with each other through the communication bus; The memory is used to store computer programs; The processor is used to implement the steps of the BRT trunk green wave control method described in any one of claims 1-6 when executing the program stored in the memory.

Images