Method and system for evaluating static overtaking distance of articulated bus

Abstract

The invention discloses an articulated bus static overtaking distance evaluation method and system, and the method comprises the steps: calculating the maximum limit value from the in-situ rotation of a steering wheel of a vehicle to the leftward / rightward direction of a steering system, keeping the steering angle of the steering wheel unchanged, and enabling the vehicle to run at the lowest stable vehicle speed V until the vehicle is parked; simulating an overtaking working condition, judging whether the driving track meets a constraint condition or not, if yes, generating a vehicle contour envelope line, and calculating a static overtaking distance. The problem that the static overtaking distance parameter of the articulated bus is difficult to calculate is effectively solved, the simulation method is based on open-loop control, the success rate is high, and the simulation result is easy and visual to display.

Description

Technical Field

[0001] The invention relates to the technical field of automobile control, in particular to a static overtaking distance evaluation method and system for an articulated bus. Background Art

[0002] As a bus with a large passenger capacity but poor turning ability, maneuverability and passability, articulated buses have attracted more attention for their low-speed passing performance than other types of buses. Static overtaking distance is an evaluation index of low-speed passing performance, which evaluates the vehicle's execution Figure 1 Maneuver shown: measure distance X, which is the minimum distance between two vehicles required to overtake a stationary vehicle with an offset of 4m (relative to the vehicle being overtaken). This parameter reflects the low-speed passing performance of the vehicle in the traffic flow. Unlike conventional tests such as the minimum turning diameter and the minimum channel circle diameter, the vehicle does not maintain a fixed turning radius during the test. At the same time, due to the characteristics of articulated vehicles, the swing of the rear compartment lags behind the movement trajectory of the front compartment and changes over time. The movement process of the entire vehicle is relatively complex, so it is difficult to simply calculate the parameters like the minimum turning diameter, the minimum channel circle diameter and other parameters. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a static overtaking distance evaluation method and system for an articulated bus in view of the deficiencies in the prior art, so as to effectively solve the problem that the static overtaking distance parameters of an articulated bus are difficult to calculate.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a static overtaking distance evaluation method for an articulated bus, comprising the following steps:

[0005] S1. Calculate the time t1 for the vehicle to stop at the minimum stable speed V while turning the steering wheel in situ to the maximum limit value of the steering system to the left / right, keeping the steering wheel angle unchanged: Where R is the minimum turning radius, T F is the front wheelbase of the vehicle;

[0006] S2, simulating overtaking conditions, determining whether the driving trajectory meets the constraint conditions, if so, generating a vehicle contour envelope, calculating the static overtaking distance, and proceeding to step S4; otherwise, proceeding to step S3;

[0007] S3, adjust the value of t1 and return to step S2;

[0008] S4. End.

[0009] The present invention summarizes a preliminary calculation formula for input parameters, and ultimately determines the input parameters of the simulation by combining calculation with iteration, so that the simulation process can be carried out in an open-loop control manner, and the simulation result does not depend on the control strategy and related parameter settings, thereby improving the success rate of the simulation and effectively solving the problem that the static overtaking distance parameters of the articulated bus are difficult to calculate.

[0010] In step S2, the specific implementation process of simulating the overtaking condition includes:

[0011] Turn the steering wheel of the vehicle to the maximum limit value of the steering system to the left / right, keep the steering wheel steering angle unchanged, and drive at the lowest stable speed for time t1 before stopping;

[0012] After parking, turn the steering wheel to the maximum right / left limit of the steering system, keep the steering wheel angle unchanged, and then drive at the lowest stable speed for time t1 and then stop;

[0013] The vehicle turns the steering wheel to the middle position, keeps the steering wheel angle unchanged, and drives at the minimum stable speed for time t2 until the front and rear compartments enter a stable state of straight-line driving.

[0014] The simulation method of the present invention is based on open-loop control and has a high success rate.

[0015] In step S2, the constraint conditions include: the final straight-line driving direction of the vehicle is parallel to the initial driving direction, and the lateral interval is 4m.

[0016] In step S2, the specific implementation process of calculating the static overtaking distance includes:

[0017] Acquire the data of the changes of the three-dimensional marking points at the front and rear of the vehicle body over time, and use the data to draw the moving envelope of the right side contour line of the vehicle body in the XY plane;

[0018] Moving the left rear side contour line of the overtaken vehicle forward and backward so that the left rear side contour line is tangent to the right side movement envelope line of the overtaking vehicle;

[0019] Measure the longitudinal distance between the rear end point of the overtaken vehicle and the front end point of the overtaking vehicle at the initial position to obtain the static overtaking distance under the left overtaking condition.

[0020] In step S2, the specific implementation process of calculating the static overtaking distance includes:

[0021] Acquire the data of the changes of the three-dimensional marking points at the front and rear of the vehicle body over time, and use the data to draw the moving envelope of the left side contour line of the vehicle body in the XY plane;

[0022] Moving the right rear side contour line of the overtaken vehicle forward and backward so that the right rear side contour line is tangent to the left side movement envelope line of the overtaking vehicle;

[0023] Measure the longitudinal distance between the rear end point of the overtaken vehicle and the front end point of the overtaking vehicle at the initial position to obtain the static overtaking distance under the right overtaking condition.

[0024] The present invention is based on the envelope visualization method, which simply and intuitively displays the moving trajectory of the vehicle body contour line during the entire simulation process, further reducing the calculation complexity.

[0025] As an inventive concept, the present invention also provides an articulated bus static overtaking distance assessment system, which includes a memory, a processor and a computer program stored in the memory; the processor executes the computer program to implement the steps of the above method.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention effectively solves the problem that the static overtaking distance parameters of articulated buses are difficult to calculate, the simulation method is based on open-loop control, has a high success rate, and the simulation results are simple and intuitive. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of static overtaking condition;

[0028] Figure 2 The right side contour envelope of the overtaking vehicle and the left rear side contour of the overtaken vehicle in the embodiment of the present invention;

[0029] Figure 3 The figure is a flow chart of a method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. 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.

[0031] Example 1

[0032] The embodiment of the present invention provides a static overtaking distance simulation evaluation method suitable for articulated buses. First, a vehicle dynamics model is established based on parameters such as tires, suspensions, chassis layout, and vehicle weight attributes of the studied vehicle model. At the same time, in the front and rear body subsystems of the model, a series of three-dimensional coordinate points are used to mark the outer contours of the concerned parts of the body; then, based on the maximum limit value of the steering system and the minimum stable speed of the vehicle, a dynamics simulation method is used to simulate the movement of the front and rear compartments when the vehicle changes lanes in parallel and overtakes the stationary vehicle in front with the shortest forward distance; finally, the time domain parameters of the three-dimensional marking points of the outer contours of the front and rear compartments obtained by simulation are exported, and the corresponding envelope image is drawn, based on which the distance from the vehicle in front that can be allowed for overtaking is determined.

[0033] In view of the problem that the static overtaking distance parameters of articulated buses are difficult to calculate, this embodiment proposes an evaluation method based on multi-body dynamics simulation to evaluate the low-speed passing performance of the vehicle in the traffic flow during the design stage.

[0034] like Figure 3 As shown in the figure, the static overtaking distance evaluation method of articulated buses based on multi-body dynamics simulation includes:

[0035] 1. Dynamic model establishment: The vehicle dynamic model is established based on the parameters of the tires, suspension, chassis layout, vehicle weight attributes, etc. of the studied vehicle model. At the same time, in the front and rear body subsystems of the model, a series of three-dimensional coordinate points are used to mark the outer contours of the car body's focus parts (mainly the outermost contour lines of the front bumper and both sides of the car body).

[0036] 2. Overtaking condition simulation: Based on the maximum limit value of the steering system and the minimum stable speed of the vehicle, the dynamic simulation method is used to simulate the movement of the front and rear compartments when the vehicle changes lanes in parallel and overtakes the stationary vehicle in front with the shortest forward distance. The specific simulation method is (taking overtaking from the left as an example): the vehicle turns the steering wheel to the maximum limit value of the steering system to the left, then keeps the steering wheel steering angle unchanged, drives at the minimum stable speed for time t1 and then stops (the steering wheel steering angle remains unchanged); after stopping, the steering wheel is turned to the maximum limit value of the steering system to the right, then keeps the steering wheel steering angle unchanged, and then drives at the minimum stable speed for time t1 and then stops (the steering wheel steering angle remains unchanged); the vehicle turns the steering wheel to the middle position (the steering wheel angle corresponding to the vehicle's straight-line driving), then keeps the steering wheel steering angle unchanged, and drives at the minimum stable speed for time t2. Among them, the value of t2 should be set long enough so that the front and rear compartments enter the stable state of straight-line driving at the end of the simulation; t1 is first set according to the calculation result of formula (1).

[0037]

[0038] In the formula,

[0039] t1——the time required, in seconds;

[0040] V——minimum stable vehicle speed, in m / s;

[0041] R——minimum turning radius, in m;

[0042] T F ——Front wheelbase, in meters.

[0043] After the first simulation, because the t1 value used is a preliminary estimate, the vehicle's driving trajectory is generally still somewhat different from the expected one. Adjust the t1 value according to the simulation results and repeat the simulation until the vehicle's final straight-line driving direction is exactly parallel to the initial driving direction, with a lateral distance of 4m. Simulate overtaking from the left and overtaking from the left, respectively.

[0044] Data processing is performed by visualizing the envelope: After the simulation is completed, the data of the changes of each 3D marker point on the front and rear body over time is obtained. Next, the data is post-processed: at each discrete time point, these 3D marker points can be connected in the XY (top view) plane to form the body contour line corresponding to that time point; the contour line corresponding to each time point is displayed in the XY (top view) plane at the same time, and the moving envelope line of the right side contour line of the body is drawn, such as Figure 2 As shown in the figure, the left rear side profile (red dashed line) of the overtaken vehicle is moved forward and backward to make it just tangent to the right side profile envelope of the overtaking vehicle. At this time, the longitudinal distance between the rear end point of the overtaken vehicle and the front end point of the overtaking vehicle at the initial position is measured, which is the static overtaking distance X required under the left overtaking condition, as shown in Figure 2 Switch left and right and use the same process to obtain the static overtaking distance value under the right overtaking condition.

[0045] Example 2

[0046] Embodiment 2 of the present invention provides a terminal device corresponding to the above-mentioned embodiment 1. The terminal device may be a processing device for a client, such as a mobile phone, a laptop computer, a tablet computer, a desktop computer, etc., to execute the method of the above-mentioned embodiment.

[0047] The terminal device of this embodiment includes a memory, a processor, and a computer program stored in the memory; the processor executes the computer program in the memory to implement the steps of the method in the above-mentioned embodiment 1.

[0048] In some implementations, the memory may be a high-speed random access memory (RAM), and may also include a non-volatile memory, such as at least one disk memory.

[0049] In some other implementations, the processor may be a central processing unit (CPU), a digital signal processor (DSP), or other general-purpose processors of various types, which are not limited herein.

[0050] Example 3

[0051] Embodiment 3 of the present invention provides a computer-readable storage medium corresponding to the above embodiment 1, on which a computer program / instruction is stored. When the computer program / instruction is executed by a processor, the steps of the method of the above embodiment 1 are implemented.

[0052] Computer readable storage media can be tangible devices that hold and store instructions used by instruction execution devices. Computer readable storage media can be, for example, but not limited to, electronic storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, or any combination thereof.

[0053] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of complete hardware embodiments, complete software embodiments, or embodiments in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code. The scheme in the embodiments of the present application can be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.

[0054] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0055] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0056] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0057] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A static overtaking distance assessment method for an articulated bus, characterized in that: The following steps are involved: S1. Calculate the time t1 for the vehicle to stop at the minimum stable speed V while turning the steering wheel in situ to the maximum limit value of the steering system to the left / right, keeping the steering wheel angle unchanged: Where R is the minimum turning radius, T F is the front wheelbase of the vehicle; S2, simulating overtaking conditions, determining whether the driving trajectory meets the constraint conditions, if so, generating a vehicle contour envelope, calculating the static overtaking distance, and proceeding to step S4; otherwise, proceeding to step S3; S3, adjust the value of t1 and return to step S2; S4. End.

2. The static overtaking distance assessment method for an articulated bus according to claim 1, characterized in that: In step S2, the specific implementation process of simulating the overtaking condition includes: Turn the steering wheel of the vehicle to the maximum limit value of the steering system to the left / right, keep the steering wheel steering angle unchanged, and drive at the lowest stable speed for time t1 before stopping; After parking, turn the steering wheel to the maximum right / left limit of the steering system, keep the steering wheel angle unchanged, and then drive at the lowest stable speed for time t1 and then stop; The vehicle turns the steering wheel to the middle position, keeps the steering wheel angle unchanged, and drives at the minimum stable speed for time t2 until the front and rear compartments enter a stable state of straight-line driving.

3. The static overtaking distance assessment method for an articulated bus according to claim 1, characterized in that: In step S2, the constraint conditions include: the final straight-line driving direction of the vehicle is parallel to the initial driving direction, and the lateral interval is 4m.

4. The static overtaking distance assessment method for an articulated bus according to claim 1, characterized in that: In step S2, the specific implementation process of calculating the static overtaking distance includes: Acquire the data of the changes of the three-dimensional marking points at the front and rear of the vehicle body over time, and use the data to draw the moving envelope of the right side contour line of the vehicle body in the XY plane; Moving the left rear side contour line of the overtaken vehicle forward and backward so that the left rear side contour line is tangent to the right side movement envelope line of the overtaking vehicle; Measure the longitudinal distance between the rear end point of the overtaken vehicle and the front end point of the overtaking vehicle at the initial position to obtain the static overtaking distance under the left overtaking condition.

5. The static overtaking distance assessment method for an articulated bus according to claim 1, characterized in that: In step S2, the specific implementation process of calculating the static overtaking distance includes: Acquire the data of the changes of the three-dimensional marking points at the front and rear of the vehicle body over time, and use the data to draw the moving envelope of the left side contour line of the vehicle body in the XY plane; Moving the right rear side contour line of the overtaken vehicle forward and backward so that the right rear side contour line is tangent to the left side movement envelope line of the overtaking vehicle; Measure the longitudinal distance between the rear end point of the overtaken vehicle and the front end point of the overtaking vehicle at the initial position to obtain the static overtaking distance under the right overtaking condition.

6. An articulated bus static overtaking distance assessment system, comprising a memory, a processor and a computer program stored in the memory; characterized in that: The processor executes the computer program to implement the steps of the method according to any one of claims 1 to 5.

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