A method and system for monitoring traffic flow parameters at intersections based on UWB

Abstract

The present invention discloses a method and system for monitoring traffic flow parameters at an intersection based on UWB. The monitoring method comprises: step S1, establishing an intersection coordinate system model; step S2, obtaining vehicle position information P(x i ,y i ), where x i is the horizontal coordinate of the vehicle at time i in the intersection coordinate system model, y i is the ordinate of the vehicle at time i in the intersection coordinate system model; Step S3, based on the vehicle position information P(x i ,y i ) calculates traffic flow parameters; traffic flow parameters include vehicle flow direction, traffic volume Q in different directions and queue length queue(t i ). By installing UWB base stations at intersections to obtain real-time vehicle location information, it is possible to monitor the flow direction of vehicles in the intersection, the traffic volume in different directions, and the queue length in real time, provide accurate and reliable traffic flow information for traffic control, and optimize and evaluate intersection signals in real time.

Description

Technical Field

[0001] The present invention relates to the technical field of traffic flow parameter monitoring, and in particular to a method and system for monitoring traffic flow parameters at an intersection based on UWB. Background Art

[0002] At present, traffic management at intersections still adopts traditional control methods. Due to unreasonable fixed timing schemes, urban intersections are overcrowded and a lot of lane time is wasted in some directions.

[0003] Therefore, it is necessary to effectively monitor the traffic flow parameters at intersections to provide support for traffic management and planning. However, traditional methods for monitoring traffic flow parameters at intersections have problems such as low accuracy, high cost, and complex installation.

[0004] In response to the above technical problems, the present application proposes a method and system for monitoring traffic flow parameters at intersections based on UWB. Summary of the invention

[0005] The purpose of the present invention is to provide a method and system for monitoring traffic flow parameters at intersections based on UWB to solve the technical problems mentioned in the background technology. The purpose of the present invention is achieved through the following technical solutions:

[0006] A method for monitoring traffic flow parameters at an intersection based on UWB includes the following steps:

[0007] Step S1, establishing an intersection coordinate system model;

[0008] Step S2: Obtain vehicle location information P(x i ,y i );

[0009] Among them, x i is the horizontal coordinate of the vehicle at time i in the intersection coordinate system model, y i is the ordinate of the vehicle at time i in the intersection coordinate system model;

[0010] Step S3: Based on the vehicle position information P(x i ,y i ) Calculate traffic flow parameters;

[0011] Traffic flow parameters include vehicle flow direction, traffic volume Q in different directions and queue length queue(t i ).

[0012] Furthermore, the method for determining the vehicle flow direction is:

[0013] Step S21, dividing different lane areas in the intersection coordinate system model;

[0014] Step S22: Determine the vehicle's position information P(x i ,y i ) is located, and the lane area where the vehicle is located is the vehicle flow direction of the vehicle.

[0015] Further, the lane area includes a left turn lane area, a left straight lane area, a straight lane area, a straight right lane area and a right turn lane area.

[0016] Furthermore, the calculation steps of the traffic volume Q in different directions are as follows:

[0017] Step S31: Set monitoring point P in the intersection coordinate system model S ;

[0018] Step S32: Obtain the preset statistical time period U T Passing monitoring point P S The number of all vehicles in each lane area;

[0019] Step S33, obtaining the vehicle type, and calculating the equivalent number of cars in each lane area according to the vehicle conversion coefficient of highway engineering technical standards;

[0020] Step S34: Accumulate the equivalent number of cars of all vehicles in each lane area to obtain the traffic volume Q in different directions.

[0021] Further, step S32 specifically includes:

[0022] Step S321, setting the statistical time interval:

[0023] [tg T , t+U T +g T ];

[0024] Among them, t is the starting time, U T is the preset statistical time period, g T The interval time for reading the vehicle position;

[0025] Step S322: Setting monitoring point P S Monitoring interval:

[0026] [P S -eg T V s , P S +e+g T V s ];

[0027] Among them, e is the positioning accuracy, g T is the interval time for reading the vehicle position, V s is the vehicle speed;

[0028] Step S323, obtaining the number of all vehicles passing through the monitoring interval within the statistical time interval;

[0029] Step S324: Obtain the vehicle position information P closest to the monitoring interval near , calculate the vehicle from P near To P S Time t snear :

[0030]

[0031] in, P near To P S The distance, V s is the vehicle speed;

[0032] Step S325: If the vehicle position information P near At the monitoring point P S , then:

[0033] t s =t pnear +t snear

[0034] If the vehicle position information P near At the monitoring point P S Downstream of , then:

[0035] t s =t pnear -t snear

[0036] If t s ∈[t,t+U T ], then add the vehicle to the number of vehicles obtained in step S323;

[0037] Among them, t pnear The vehicle under test is at P near Time of location recording, t s The converted vehicle passes the monitoring point P S time.

[0038] Furthermore, the queue length queue(t i ) is calculated as follows:

[0039] Step S41: Determine the queue length queue(t i )’s detection range;

[0040] Step S42: Obtain t i The speed parameter v of all vehicles within the detection range at all times i ;

[0041] If t i The vehicle's location information is detected at all times.

[0042] v i =|P i P i+ΔT | / ΔT

[0043] or

[0044] v i =|P i-ΔT P i | / ΔT

[0045] If t i If the vehicle's location information is not detected at any time,

[0046] v i =|P i-ΔT P i+ΔT | / ΔT

[0047] In the formula, ΔT is the unit time, P i t i The position of the vehicle at the moment, P i-ΔT t i The position of the vehicle at the last unit time, P i+ΔT t i The position of the vehicle at the next unit of time;

[0048] Step S43: Filter vehicle speed parameter v i ≤0.2V e The total number of vehicles is calculated to get the queue length queue(t i );

[0049] Among them, V e is the expected speed.

[0050] The present invention also discloses a UWB-based intersection traffic flow parameter monitoring system, comprising:

[0051] Mobile tags, which are installed on vehicles and are used to transmit location signals;

[0052] UWB base station, several UWB base stations are installed at the entrance of the intersection, and the UWB base station is connected to the mobile tag for receiving the location signal sent by the mobile tag and generating the location parameter;

[0053] The control center is connected to each UWB base station in communication with each other to obtain the location parameters generated by each UWB base station and calculate the traffic flow parameters according to the location parameters.

[0054] Furthermore, it also includes a traffic light, which is electrically connected to a control center, and the control center adjusts the duration of the traffic light in real time according to traffic flow parameters.

[0055] The technical solution provided in the embodiments of the present application has at least the following technical effects or advantages:

[0056] By installing UWB base stations at intersections to obtain vehicle location information in real time, it is possible to monitor the flow direction, traffic volume and queue length of vehicles in the intersection in real time, provide accurate and reliable traffic flow information for traffic control, and optimize and evaluate intersection signals in real time. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The drawings in the specification, which constitute a part of this application, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0058] Figure 1 This is a flow chart of the monitoring method of the embodiment of the present application;

[0059] Figure 2 This is a schematic diagram of lane area division in an embodiment of the present application;

[0060] Figure 3 This is a flow chart of traffic volume calculation in an embodiment of the present application;

[0061] Figure 4 This is a flowchart of queue length calculation in an embodiment of the present application;

[0062] Figure 5 This is a schematic diagram of the UWB base station layout according to an embodiment of the present application.

[0063] The accompanying drawings show: 1. mobile tag; 2. UWB base station. DETAILED DESCRIPTION

[0064] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the drawings and specific implementation methods of the specification. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0065] Example 1

[0066] like Figure 1 A method for monitoring traffic flow parameters at an intersection based on UWB is shown, comprising the following steps:

[0067] Step S1, establishing an intersection coordinate system model;

[0068] The intersection coordinate system model is obtained through RTK surveying and mapping. The intersection coordinate system model uses the length direction of the entrance as the horizontal coordinate X and the width direction of the entrance as the vertical coordinate Y, and the vertical coordinate Y direction is divided into several lanes.

[0069] Step S2: Obtain vehicle location information P(x i ,y i );

[0070] Among them, x i is the horizontal coordinate of the vehicle at time i in the intersection coordinate system model, y i is the ordinate of the vehicle at time i in the intersection coordinate system model;

[0071] Step S3: Based on the vehicle position information P(x i ,y i ) Calculate traffic flow parameters;

[0072] Traffic flow parameters include vehicle flow direction, traffic volume Q in different directions and queue length queue(t i ).

[0073] Among them, the method for determining the vehicle flow direction is:

[0074] Step S21, dividing different lane areas in the intersection coordinate system model; the lane area can be divided into a left turn lane area, a left straight lane area, a straight lane area, a straight right lane area and a right turn lane area.

[0075] Step S22: Determine the vehicle's position information P(x i ,y i ) is located, and the lane area where the vehicle is located is the vehicle flow direction of the vehicle.

[0076] like Figure 2 As shown in the figure, taking a common intersection as an example, the entrance road is generally set up with three lanes: left, straight, and right. Right-turning vehicles are generally not controlled by traffic lights. The entrance lane area is divided into a left-turn lane area and a straight-right lane area, corresponding to the left-turn phase and the straight-right phase. Among them, the left-turn lane area is represented by the Poly1 (P1, P2, P3, P4) polygon, and the straight-right lane area is represented by the Poly2 (P3, P4, P5, P6) polygon. If the vehicle's position information P (x i ,y i ) is within the range of Poly1, the vehicle flow direction of the vehicle is "turn left"; if the vehicle position information P(x i ,y i) is within the range of Poly2, the vehicle flow direction of the vehicle is “straight right”.

[0077] like Figure 3 As shown in the figure, the calculation steps of traffic volume Q in different directions are:

[0078] Step S31: Set monitoring point P on the horizontal axis X S ;

[0079] Step S32: Obtain the preset statistical time period U T Passing monitoring point P S The number of all vehicles in different lane areas;

[0080] Specifically include:

[0081] Step S321, set the statistical time interval: Since the UWB base station obtains the vehicle position at a certain time interval g T Therefore, when determining the traffic volume statistics time interval, it is necessary to use g T Taking this into account, the statistical time interval is [tg T , t+U T +g T ];

[0082] Among them, t is the starting time, U T is the preset statistical time period, g T The interval time for the UWB base station to read the vehicle position;

[0083] Step S322: Setting monitoring point P S Monitoring interval: Since there is a certain error in UWB positioning, and the UWB base station reads the time interval g T The vehicle will generate a certain amount of displacement, and the monitoring interval is set as: [P S -eg T V s , P S +e+g T V s ];

[0084] Among them, e is the positioning accuracy, g T is the interval time for reading the vehicle position, V s is the vehicle speed, V s It is obtained by dividing the vehicle displacement in the previous sampling interval by the sampling interval.

[0085] Step S323, obtaining the number of all vehicles passing through the monitoring interval within the statistical time interval;

[0086] Due to the problem of reading time interval, some vehicles pass through the monitoring point P SHowever, they are not recorded, so it is necessary to judge these vehicles through trajectory interpolation. The specific steps are as follows:

[0087] Step S324: Obtain the vehicle position information P closest to the monitoring interval near , calculate the vehicle from P near To P S Time t snear :

[0088]

[0089] in, P near To P S The distance, V s is the vehicle speed, V s It is obtained by dividing the displacement of the vehicle in the previous sampling interval by the sampling interval;

[0090] Step S325: If the vehicle position information P near At the monitoring point P S , then:

[0091] t s =t pnear +t snear

[0092] If the vehicle position information P near Downstream of the monitoring point PS, then:

[0093] t s =t pnear -t snear

[0094] If t s ∈[t,t+U T ], then add the vehicle to the number of vehicles obtained in step S323;

[0095] Among them, t pnear The vehicle under test is at P near Time of location recording, t s The converted vehicle passes the monitoring point P S time.

[0096] Step S33: Obtain the vehicle type, and calculate the number of equivalent cars in each lane area according to the vehicle conversion coefficient of the highway engineering technical standard; obtain the vehicle type according to the information recorded by the mobile tag, and convert different models into corresponding equivalent cars. The vehicle conversion coefficient standard is shown in the following table:

[0097] Vehicle Type Passenger car Large passenger car Large truck Articulated Truck Conversion factor 1.0 2.0 2.5 3.0

[0098] Step S34: accumulate the equivalent number of cars of all vehicles in each lane area to obtain the traffic volume Q in different directions. That is, all vehicles in each lane area are multiplied by the corresponding conversion coefficient according to their vehicle type and accumulated to obtain the traffic volume Q in each lane area, that is, the traffic volume Q in different directions.

[0099] At the intersection, due to the existence of red lights, vehicles on the entrance road will queue at the stop line, and because there are continuous vehicles arriving from upstream, queuing is a dynamic concept. i Queue length queue(t i ) is changing.

[0100] like Figure 4 As shown, the queue length queue(t i ) is calculated as follows:

[0101] Step S41: Determine the queue length queue(t i ) detection range; the detection range is a certain length range of a single lane from the stop line to the back.

[0102] Step S42: Obtain t i The speed parameter v of all vehicles within the detection range at all times i ;

[0103] Since the acquisition of vehicle position information is not continuous, if t i The vehicle's location information is detected at all times.

[0104] v i =|P i P i+ΔT | / ΔT

[0105] or

[0106] v i =|P i-ΔT P i | / ΔT

[0107] If t i If the vehicle's location information is not detected at any time,

[0108] v i =|P i-ΔT P i+ΔT | / ΔT

[0109] In the formula, ΔT is the unit time, P i t i The position of the vehicle at the moment, P i-ΔT t i The position of the vehicle at the last unit time, P i+ΔT t iThe position of the vehicle at the next unit of time;

[0110] Step S43: Filter vehicle speed parameter v i ≤0.2V e The total number of vehicles is calculated to get the queue length queue(t i ). According to the principles of traffic engineering, the expected speed V on different levels of roads e Different, when the vehicle speed v i ≤0.2V e When , it is determined that the vehicle is in a queue state.

[0111] Example 2

[0112] like Figure 5 The UWB-based intersection traffic flow parameter monitoring system shown includes a mobile tag 1, a UWB base station 2 and a control center (not shown):

[0113] The mobile tag 1 is installed on the vehicle to transmit the location signal. The mobile tag 1 is installed on the windshield on the upper right side of the co-pilot of the vehicle under test, so that the installation tag is out of the driver's sight to avoid any interference with the driver's observation of the road conditions. At the same time, this position is usually far away from the metal structure of the vehicle, which reduces the shielding and interference of the wireless communication signal, ensures the communication capability, and can transmit the signal with the communication equipment as quickly as possible.

[0114] UWB base station 2 is installed at the entrance of the intersection. UWB base station 2 is connected to mobile tag 1 for receiving the location signal sent by mobile tag 1 and generating location parameters. UWB base station is required to monitor the maximum queue length. One is installed at each entrance. It is installed at the center of the maximum queue length. UWB base station can receive the signal sent by the mobile tag at the front of the vehicle at the first time to reduce the time error in the transmission signal. The installation height of UWB base station shall not be less than 2m. The spacing between UWB base stations is determined according to the coverage range of the factory base station. At the same time, in order to reduce the cost of setting up a separate pole, UWB base station can be installed using existing monitoring equipment poles, street light poles or sign poles.

[0115] The control center is connected to each UWB base station in communication to obtain the location parameters generated by each UWB base station and calculate the traffic flow parameters based on the location parameters. The data read by the UWB base station is transmitted to the control center wirelessly to complete the data storage of the vehicle location information, and the traffic flow parameters of the research monitoring area are obtained based on the above algorithm. The traffic flow is evaluated through the traffic flow state recognition model to provide decision-making and control support to the traffic management department.

[0116] As a preferred embodiment of the present application, the monitoring system further includes a traffic light, which is electrically connected to a control center, and the control center adjusts the duration of the traffic light in real time according to traffic flow parameters. For example, if the length of the vehicle queue in a lane in a certain direction exceeds a threshold, the green light time of the lane is appropriately increased in combination with the traffic flow parameters of other lanes in the other directions.

[0117] The technical solution provided in the embodiments of the present application has at least the following technical effects or advantages:

[0118] By installing UWB base stations at intersections to obtain vehicle location information in real time, it is possible to monitor the flow direction, traffic volume and queue length of vehicles in the intersection in real time, provide accurate and reliable traffic flow information for traffic control, and optimize and evaluate intersection signals in real time.

[0119] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A monitoring system based on UWB intersection traffic flow parameter monitoring method, characterized in that: include: A mobile tag, which is installed on the vehicle and is used to transmit a location signal; UWB base stations, several of which are installed at the entrances of the intersections, and the UWB base stations are communicatively connected with the mobile tags to receive location signals sent by the mobile tags and generate location parameters; A control center, the control center is respectively connected to the UWB base stations for obtaining the location parameters generated by the UWB base stations and calculating the traffic flow parameters according to the location parameters; The detection method includes the following steps: Step S1, establishing an intersection coordinate system model; The intersection coordinate system model takes the length direction of the entrance as the horizontal coordinate X, and the width direction of the entrance as the vertical coordinate Y; Step S2: Obtain vehicle location information ; in, for The horizontal coordinate of the vehicle in the intersection coordinate system model at the moment, for The ordinate of the vehicle at the moment in the intersection coordinate system model; Step S3: Based on the vehicle's location information Calculate traffic flow parameters; The traffic flow parameters include vehicle flow direction, traffic volume Q in different flow directions and queue length ; The method for determining the vehicle flow direction is: Step S21, dividing different lane areas in the intersection coordinate system model; Step S22: Determine the vehicle's location information The lane area where the vehicle is located is the vehicle flow direction of the vehicle; The calculation steps of the traffic volume Q in different directions are: Step S31: Setting monitoring points in the intersection coordinate system model ; Step S32: Obtaining a preset statistical time period Passing monitoring point The number of all vehicles in each lane area; Step S33, obtaining the vehicle type, and calculating the equivalent number of cars in each lane area according to the vehicle conversion coefficient of the highway engineering technical standard; Step S34, accumulating the equivalent number of cars of all vehicles in each lane area to obtain the traffic volume Q in different directions; The queue length The calculation steps are: Step S41: Determine the queue length Detection range; Step S42: Obtain Always detect the speed parameters of all vehicles within the range ; like The vehicle's location information is detected at all times. or like If the vehicle's location information is not detected at any time, In the formula, is the unit time, for The vehicle's position at the moment, for The position of the vehicle at the previous unit time, for The position of the vehicle at the next unit of time; Step S43: Filter vehicle speed parameters The total number of vehicles is calculated to get the queue length ; in, is the expected speed.

2. A monitoring system based on the UWB intersection traffic flow parameter monitoring method according to claim 1, characterized in that: The lane area includes a left-turn lane area, a left straight lane area, a straight lane area, a straight right lane area and a right-turn lane area.

3. A monitoring system based on the UWB intersection traffic flow parameter monitoring method according to claim 1, characterized in that: Step S32 specifically includes: Step S321, setting the statistical time interval: ； in, is the starting time, To preset statistical time period, The interval time for reading the vehicle position; Step S322: Setting monitoring points Monitoring interval: ； in, is the positioning accuracy, The interval time for reading the vehicle position, is the vehicle speed; Step S323, obtaining the number of all vehicles passing through the monitoring interval within the statistical time interval; Step S324: Obtain the vehicle location information closest to the monitoring area , calculate the vehicle from arrive Time : in, for arrive The distance is the vehicle speed; Step S325: If the vehicle location information At the monitoring point , then: If the vehicle location information At the monitoring point Downstream of , then: if , then add the vehicle to the number of vehicles obtained in step S323; in, For the vehicle under test The time of location record, The converted vehicle passes the monitoring point time.

4. A monitoring system based on the UWB intersection traffic flow parameter monitoring method according to claim 1, characterized in that: It also includes a traffic light, which is electrically connected to the control center, and the control center adjusts the duration of the traffic light in real time according to traffic flow parameters.

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