CN114670901B - Multi-train cooperative cruise control method and system based on potential function - Google Patents
Multi-train cooperative cruise control method and system based on potential function Download PDFInfo
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Abstract
The invention discloses a multi-train cooperative cruise control method and a multi-train cooperative cruise control system based on a potential function, wherein the method comprises the following steps: acquiring real-time running information of each train in a multi-train system; calculating the distance deviation between each train and other trains; constructing a potential function between two trains based on the actual tracking distance and the expected safe distance of the trains; calculating the negative gradient of the potential function of each train and other trains to obtain the negative feedback of each train; and constructing a control variable of each train and acting on a traction braking system of the train to generate traction force or braking force, wherein the control variable at least comprises negative feedback of the train obtained based on a train potential function. And the invention further optimizes the potential function and designs the potential function as an asymmetric adjustable potential function. The method controls the distance between the high-speed trains within a safe range by designing the artificial potential function, and prompts the distance between the trains to be dynamically adjusted according to the real-time running state of the trains so as to meet the requirement of safe and efficient running of the trains.
Description
Technical Field
The invention belongs to the technical field of train operation control, and particularly relates to a potential function-based multi-train cooperative cruise control method and system.
Background
The high-speed train has great advantages in the field of transportation by virtue of the characteristics of large bearing capacity, safety, rapidness and the like. With the increase of the number of trains in operation, how to realize the cooperative operation control of multiple trains, shorten the train tracking operation interval and improve the overall operation efficiency of railways becomes a research subject which is widely concerned in the field.
The multi-high-speed train cooperative cruising is an effective solution for improving the railway operation efficiency. The research results obtained from the aspects of multi-train operation control at home and abroad are quite rich, the communication mode comprises two communication modes based on a CBTC system and a train-train communication technology, and a multi-agent system theory, an artificial potential field theory and the like are introduced, so that the operation performance of the train is improved. However, most studies control the distance between trains to be a fixed constant or limit the distance to be within a fixed range interval, but the boundary of the safety range is usually a fixed value, and for safety reasons, the safety boundary is set to be slightly larger, and even if the speed of the train is slow, the phase is used
The same security boundaries. When speed limit adjustment or other emergency situations occur, the running speed of the train changes, but the distance cannot be correspondingly adjusted, so that the flexibility of the train control system is reduced.
Aiming at the current situations of heavy transportation tasks and complex operation environment of high-speed trains, the invention develops further research aiming at the problem of train group cooperative control, considers the dynamic coupling relation of train workshops, and optimizes the train tracking interval along with the actual speed of the trains on the premise of ensuring the safe operation of the trains so as to improve the overall operation efficiency of the railway.
Disclosure of Invention
The invention aims to solve the technical problem that in the prior art, the distance between trains is controlled to be a fixed constant or limited in a fixed range interval, and the distance cannot be correspondingly adjusted when the running speed of the train changes, and further provides a multi-train cooperative cruise control method and system based on a potential function. The method of the invention is oriented to the high-efficiency operation requirements of high-density and small spacing of high-speed trains, takes a multi-high-speed train system as a research object, designs an artificial potential function, controls the distance between the high-speed trains within a safe range, and dynamically adjusts the distance between trains according to the real-time operation state of the trains so as to meet the requirements of the safe and high-efficiency operation of the trains.
In one aspect, the invention provides a multi-train cooperative cruise control method based on a potential function, which comprises the following steps:
step 1: acquiring real-time running information of each train in a multi-train system, wherein the real-time running information comprises speed information and position information;
step 2: calculating the distance deviation between each train and other trains based on the real-time running information of each train; wherein the distance deviation between two trains represents the actual tracking distance of the trains;
and step 3: representing the deviation between the actual tracking distance and the expected safe distance of the train by using the artificial potential field, and further constructing a potential function between two trains based on the actual tracking distance and the expected safe distance of the train; wherein the desired safe distance is positively correlated to the actual speed of the train;
and 4, step 4: calculating the negative gradient of the potential function of each train and other trains to obtain the negative feedback of each train;
and 5: and constructing a control variable of each train and acting on a traction braking system of the train to generate traction or braking force so as to control the acceleration change of each train, wherein the control variable at least comprises negative feedback of the train obtained based on a train potential function.
According to the technical scheme of the multi-train cooperative cruise control method, on one hand, the expected safe distance of the train is adjusted according to the actual speed of the train, and when the speed of the train is reduced, the expected safe distance is reduced; when the train speed is faster, the expected safe distance increases. And on the other hand, representing the deviation between the actual tracking distance and the expected safety distance of the train by using the artificial potential field, and further constructing a potential function. When the actual tracking distance of the train is greater than the expected safety distance, generating attractive force based on the artificial potential field of the potential function to accelerate the rear train so as to reduce the distance between the rear train and the front train; and when the actual tracking distance of the train is less than the expected safety distance, generating repulsive force based on the artificial potential field of the potential function, so that the rear train decelerates, and the distance between the rear train and the front train is increased. In conclusion, the technical scheme provided by the invention can adjust the safety distance between train workshops according to the actual running speed of the train, effectively shorten the train tracking distance when the speed is reduced, and improve the overall operation efficiency of the railway.
Optionally, the potential function between two trains is represented as:
wherein, U (d) ij ) As a function of the potential between train i and train j,
the acting force of an artificial potential field between the train i and the train j on the rear train is shown, a is a positive coefficient,
is the maximum tractive effort or the maximum braking effort produced by the train traction brake system, d ij Is the distance deviation between train i and train j, d r A desired safe distance.
Optionally, the potential function is an adjustable potential function, and the positive coefficient a is an adjustable positive coefficient;
adjusting or determining the value of the adjustable correction coefficient a according to the offset degree of the allowed actual tracking distance and the expected safe distance, wherein the larger the allowed offset degree is, the larger the adjustable correction coefficient a is; the smaller the allowed offset, the smaller the adjustable positive coefficient a.
The potential function designed by the invention ensures that the distance between the trains has the minimum potential energy when the distance is at the expected safe distance, and the artificial potential field does not generate acting force on the trains. The shape of the artificial potential function is related to the value of the parameter a, and if the parameter a is relatively small, the potential function only has low potential energy at an expected safe distance; if the parameter a is relatively large, at the desired safe distance d r Within a certain range nearby, potential energy generated by the potential function is low. Therefore, the larger the value of the parameter a is, the larger the range of the potential function has low potential energy, and in this range, the control input generated by the potential function is almost zero, and the steady-state distance is distributed in this range. Therefore, can be based on the fact thatAnd setting a proper parameter a according to the tolerance degree of the deviation of the inter-tracking distance from the expected safe distance, wherein the larger the tolerance degree is, the larger a steady-state distance interval corresponding to the low potential energy of the potential function is, and the larger the value of the corresponding parameter a is.
Optionally, the potential function is an asymmetric artificial potential function, wherein the corresponding force F p (d ij ) Expressed as:
wherein, a 1 ,a 2 All represent a positive coefficient a, and a 2 Greater than a 1 。
In a train control system, there is a high requirement for train operation safety, and if the actual operating distance is less than the expected distance, there is a risk of collision in case of emergency, and therefore, the shape of the potential function in the direction of less than the expected distance should be steeper. If the actual running distance is greater than the expected distance, the carrying capacity of the line is only affected, and no threat is caused to the running safety, so that the potential function can be more gradual in the direction greater than the expected distance, and the action times of the controller are reduced. Therefore, the invention sets an asymmetric artificial potential function by taking the expected safe distance as a demarcation point.
Optionally, for any train, the negative feedback of the train based on its negative gradient with the potential function of the other trains is represented as:
wherein u is i2 Negative feedback for train i; a is a ij Indicating whether communication exists between the train i and the train j, and if communication exists, a ij Is 1, otherwise a ij Is 0; n is the total number of trains, x, of the multi-train system i Indicating the location of train i.
If the train i and the train j with communication are adjacent trains, the expected safe distance d r (t)＝v i *h * +d 0 ，d 0 Given a minimum safety distance, h * Given a desired headway, v, between adjacent trains i Is the actual speed of train i;
if the train i and the train j with communication are non-adjacent trains, the expected safe distance d r (t)＝(j-i)(v i *h * +d 0 )。
Whether potential function acting force exists between the trains or not is judged whether communication exists between the two trains or not, and if the communication exists, the acting force exists. In practice, it is usually only considered that adjacent trains can communicate with each other, and therefore, when only communication between adjacent trains is considered, "other trains" in steps 2-4 are understood as adjacent trains.
In order to reduce the amount of computation, if communication between adjacent trains is not considered, the "other train" in steps 2 to 4 is understood as another train with communication. In other implementations, no constraint may be placed on "other trains".
Optionally, the control variable of the train further comprises a control feedback based on a speed deviation of the train, the control feedback for controlling the train speed to track the desired speed, expressed as:
wherein u is i1 For control feedback of train i based on speed deviation, m i Is the mass of train i, v i 、v j Is the actual speed, v, of train i, train j r Is the desired speed of train i; a is a ij Indicating whether communication exists between the train i and the train j, if the communication exists, a ij Is 1, otherwise a ij 0n is the total number of trains of the multi-train system, alpha>0 is a positive coefficient.
In a second aspect, the invention provides a multi-train cooperative cruise control method based on a potential function, which is applied to a single train of a multi-train cooperative control system, and the multi-train cooperative cruise control method includes the following steps:
step S1: the method comprises the steps that a current train acquires real-time running information of the current train and other trains, wherein the real-time running information comprises speed information and position information;
step S2: based on the real-time running information, the current train calculates the distance deviation between the current train and other trains; wherein the distance deviation between two trains represents the actual tracking distance of the trains;
and step S3: representing the deviation between the actual tracking distance and the expected safe distance of the train by using the artificial potential field, and further constructing a potential function between the current train and other trains based on the actual tracking distance and the expected safe distance of the train; wherein the desired safe distance is positively correlated to the actual speed of the train;
and step S4: the current train calculates the negative gradient of the potential function of the current train and other trains to obtain the negative feedback of the train;
step S5: and constructing a control variable of the current train and acting on a traction braking system of the train to generate traction or braking force so as to control the acceleration change of the train, wherein the control variable at least comprises negative feedback of the train obtained by the current train based on the negative gradient of the train potential function.
In a third aspect, the present invention provides a system based on the multi-train cooperative cruise control method, including: the system comprises a multi-train system, an operation information acquisition subsystem, a train communication subsystem and a control subsystem;
the multi-train system consists of a plurality of trains;
the running information acquisition subsystem consists of vehicle-mounted equipment and/or trackside equipment of each train and is used for acquiring real-time running information of each train;
the train communication subsystem is composed of communication modules and/or wireless block centers of all trains and is used for constructing communication connection among the trains and realizing information transmission among the adjacent trains;
and the control subsystem is composed of controllers of all trains and is used for obtaining or acquiring control variables of all trains according to the steps 2-5 or the steps S2-S5 and acting on a traction braking system of the trains to generate traction force or braking force so as to control the acceleration change of the trains.
In a fourth aspect, the present invention provides an electronic terminal, comprising:
one or more processors;
a memory storing one or more computer programs;
the processor invokes the computer program to implement: provided is a multi-train cooperative cruise control method based on a potential function.
In a fifth aspect, the present invention provides a readable storage medium storing a computer program for invocation by a processor to implement:
provided is a multi-train cooperative cruise control method based on a potential function.
Advantageous effects
1. According to the multi-high-speed train cooperative cruise control method based on the potential function, on one hand, the expected safe distance of the train is adjusted according to the actual speed of the train, and when the speed of the train is reduced, the expected safe distance is reduced; when the train speed is higher, the expected safety distance is increased; on the other hand, representing the deviation between the actual tracking distance and the expected safe distance of the train by using the artificial potential field to further construct a potential function, wherein when the actual tracking distance of the train is greater than the expected safe distance, the artificial potential field pair based on the potential function generates attraction to accelerate a rear train so as to reduce the distance between the rear train and a front train; and when the actual tracking distance of the train is less than the expected safety distance, generating repulsive force based on the artificial potential field of the potential function, so that the rear train decelerates, and the distance between the rear train and the front train is increased. Therefore, the strategy provided by the invention can adjust the safety distance between train workshops according to the train running speed, effectively shorten the train tracking distance when the speed is reduced, and improve the overall operation efficiency of the railway on the premise of ensuring the train running safety.
2. In a further optimization scheme of the invention, a potential function is optimized and set as an adjustable potential function, the range of the steady-state safe distance can be flexibly changed by adjusting the parameter a of the potential function, the smaller the parameter value is, the higher the accuracy of the train tracking the expected safe distance is, and when the parameter value is larger, the steady-state distance between trains is allowed to be distributed in a range near the expected distance. Namely, parameters of the potential function are changed according to the degree of the actual distance allowed by the dispatcher to deviate from the expected safe distance, so that the distance between the high-speed trains is controlled within a safe range, and certain tolerance is realized. Meanwhile, the potential function is further designed into an asymmetric potential function, and the train operation safety is improved.
3. In a further optimization scheme of the invention, apart from realizing distance control, the method can also accurately track the expected speed, so that the speed of each high-speed train is kept consistent and the distance between trains is kept unchanged when the train group runs in a stable state.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a flow chart of a preferred embodiment of a method for controlling multi-high speed train cooperative cruise based on a potential function according to the present invention;
FIG. 2 is a block diagram of a cooperative controller based on an adjustable potential function according to the present invention;
FIG. 3 is an exemplary graph of an asymmetric artificial potential function as a function of actual distance provided by the present invention;
FIG. 4 is a graph of the force Fp (d) generated by an asymmetric artificial potential field provided by the present invention ij ) According to the actual distance d ij The graph illustrates the variation.
Fig. 5 is a graph of the artificial potential function as a function of parameter a.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1:
in order to solve the technical problem that the distance between train cars is controlled on a fixed constant or limited in a fixed range interval in the prior art, and the distance cannot be adjusted correspondingly when the running speed of a train changes, the invention provides a multi-train cooperative cruise control method and a system based on a potential function, wherein the expected safety distance of the train is adjusted according to the actual speed of the train, then a potential function which represents the deviation between the actual tracking distance and the expected safety distance of the train based on an artificial potential field is designed, the expected safety distance is adjusted along with the actual speed of the train, and when the actual tracking distance of the train is greater than the expected safety distance, the artificial potential field based on the potential function generates attraction force to accelerate a rear train, so that the distance between the rear train and a front train is reduced; and when the actual tracking distance of the train is less than the expected safety distance, the artificial potential field based on the potential function generates repulsive force, so that the rear train decelerates, and the distance between the rear train and the front train is increased. In the present embodiment, it is set that communication exists between adjacent trains, that is, the acting force of the potential function exists, and non-adjacent trains do not exist. Therefore, the multi-train cooperative cruise control method based on the potential function provided by the embodiment comprises the following steps:
step 1: the method comprises the steps of obtaining real-time running information of each train in a multi-train system, wherein the real-time running information comprises speed information and position information.
In this embodiment, the train acquires real-time running information of the train from the on-board device and the trackside device through the on-board communication module, and communicates with the radio block center through the communication module to transmit train state information to an adjacent train in real time, and acquires real-time state information of the adjacent train. The train state information includes real-time operation information or state information obtained based on the real-time operation information.
Step 2: calculating the distance deviation between each train and the adjacent train based on the real-time running information of each train; wherein the distance deviation between adjacent trains represents the actual tracking distance of the train.
In this step, the actual speed and position of the train i at time t are respectively represented as v i (t) and x i (t); the distance deviations between train i and train j at time t are x j (t)-x i (t) of (d). For the sake of brevity, the following parametric expressions for speed and distance do not add time t.
And step 3: representing the deviation between the actual tracking distance and the expected safe distance of the train by utilizing the artificial potential field, and further constructing a potential function between two trains based on the actual tracking distance and the expected safe distance of the train; wherein the desired safe distance is positively correlated to the actual speed of the train.
The established potential function based on the distance deviation between adjacent trains is as follows:
wherein, the first and the second end of the pipe are connected with each other,
which represents the acting force on the rear train caused by the artificial potential field between the train i and the train j, a is a positive coefficient,
is the maximum tractive force or the maximum braking force generated by the train traction braking system, d ij (t)＝|x i (t)-x j (t) | is the actual distance (actual tracking distance) between train i and train j at time t, d r (t)＝v i (t)*h * +d 0 The expected safety distance is changed along with the speed of the train, when the speed of the train is reduced, the expected safety distance is reduced, and when the speed is higher, the expected safety distance is increased. Wherein d is 0 Given a minimum safety distance, h * To give a desired headway between adjacent trains, h is selected in this embodiment * ＝60s，d 0 =4km, assume v i (t) =36km/h, d r ＝10km。
As shown in fig. 3, the potential function designed by the present invention will have a minimum potential energy at the desired distance when the artificial potential field is not producing a force on the train. As shown in fig. 4, when the actual distance is greater than the desired distance, the artificial potential field generates an attractive force to accelerate the trailing vehicle to reduce the distance to the leading vehicle; when the actual distance is less than the expected distance, the artificial potential field can generate repulsive force in the opposite direction, so that the rear vehicle is decelerated to increase the tracking running interval.
It should be understood that the potential function designed in this embodiment can meet the basic requirements of the present invention and solve the technical problems thereof, but in order to improve the multi-train cooperative control effect, the present invention further optimizes the potential function, designs an adjustable potential function, and the positive coefficient a is an adjustable positive coefficient, which will be specifically described in the next embodiment.
And 4, step 4: and calculating the negative gradient of the potential function of each train and the adjacent trains to obtain the negative feedback of each train. In which the direction of the force is represented by a gradient. The negative feedback for this train is represented as:
wherein, a ij And the communication is shown whether the high-speed train i and the high-speed train j exist, if so, the communication is 1, otherwise, the communication is 0.n is the total number of trains in the multi-train system, x i Indicating the location of train i.
And 5: and constructing control variables of each train, and acting on a traction braking system of the train to generate traction or braking force so as to control the acceleration change of each train, wherein the control variables at least comprise negative feedback of the train obtained based on a train potential function.
It should be understood that the control variable in this embodiment is the control input, i.e., the magnitude of the acceleration of the train, which is communicated to the traction brake system to generate a responseMagnitude tractive or braking force. Furthermore, the present embodiment only restricts negative feedback of the train to be taken into account in the control variables and does not restrict other configurations of the control variables, and therefore, the constructed control variables can be set to components based on other requirements of train system control. In this embodiment, λ is 2 u i2 As part of the control variable.
It should be noted that, in this embodiment, only the adjacent trains are considered to be able to communicate with each other, in other possible embodiments, the existence of communication between non-adjacent trains can also be considered, and in case of a non-adjacent train, the expected safety distance d between the non-adjacent trains is considered r (t)＝(j-i)(v i *h * +d 0 ). Similarly, the following embodiments have the same rule.
Example 2:
on the basis of embodiment 1, this embodiment further optimizes the cruise control method for the multi-train system, and on one hand, designs a potential function as an adjustable potential function, and according to the tolerance of the deviation between the actual tracking distance and the expected safe distance, by designing an adjustable positive coefficient of the adjustable potential function, the range of the safe distance distribution in a steady state is controllable; on the other hand, the adjustable potential function is designed into an asymmetric potential function, so that the requirement of controlling safe running of the train is further met; furthermore, the control variables designed in this embodiment take into account the speed of the train tracking the desired speed and overcoming drag during operation, in addition to negative feedback of the train based on the potential function. Therefore, the technical effect of the present embodiment 2 is better than that of the embodiment 1, and the present embodiment is considered as the best embodiment of the present invention.
As shown in fig. 1, the multi-train cooperative cruise control method based on the potential function provided in embodiment 2 includes the following steps:
s01: the method comprises the steps of obtaining real-time running information of each train in a multi-train system, wherein the real-time running information comprises speed information and position information.
In the embodiment, the train acquires the real-time running information of the train from the vehicle-mounted equipment and the trackside equipment through the vehicle-mounted communication module, transmits the train state information to the adjacent train in real time through the communication between the communication module and the wireless blocking center, and acquires the real-time state information of the adjacent train. The train state information includes real-time operation information or state information obtained based on the real-time operation information.
S02: calculating a speed deviation of an actual running speed of each train from an expected speed and calculating a speed deviation and a distance deviation between each train and an adjacent train based on the real-time running information of each train; wherein the distance deviation between adjacent trains represents the actual tracking distance of the train.
In this step, the actual speed and position of the train i at time t are represented as v i (t) and x i (t), the desired speed of the train i at time t is denoted v r (t), the speed deviation between the train i and the desired speed at time t is v r (t)-v i (t); the speed deviation and distance deviation between train i and train j at time t are respectively: v. of j (t)-v i (t)，x j (t)-x i (t) of (d). For the sake of brevity, the following parametric expressions for speed and distance do not add time t.
S03: representing the deviation between the actual tracking distance and the expected safe distance of the train by using the artificial potential field, and further constructing a potential function between two trains based on the actual tracking distance and the expected safe distance of the train; wherein the desired safe distance is positively correlated to the actual speed of the train.
The adjustable potential function based on the distance deviation between adjacent trains established in this embodiment is:
in the present embodiment, the first and second electrodes are,
representing the force on the trailing train caused by the artificial potential field between train i and train j, a being an adjustable positive coefficient.
In a train control system, there is a high requirement for train operation safety, and if the actual operating distance is less than the expected distance, there is a risk of collision in case of emergency, and therefore, the shape of the potential function in the direction of less than the expected distance should be steeper. If the actual running distance is greater than the expected distance, the carrying capacity of the line is only affected, and no threat is caused to the running safety, so that the potential function can be more gradual in the direction greater than the expected distance, and the action times of the controller are reduced.
To this end, the present embodiment constitutes an asymmetric artificial potential function.
S04: and selecting potential function parameters to form an asymmetric artificial potential function. For this reason, the corresponding force is expressed as:
wherein, a 1 ,a 2 All represent positive coefficients, and a 2 Greater than a 1 . In this example a 1 ,a 2 1 and 2 respectively.
Regarding the value of the positive coefficient a, as shown in fig. 5, the shape of the artificial potential function is related to the value of the parameter a, and if the parameter a is relatively small, the potential function has a low potential energy only at an expected distance; if the parameter a is relatively large, at the desired distance d r Within a certain range nearby, the potential energy generated by the potential function is lower. The larger the value of the parameter a is, the larger the range of the potential function has low potential energy, in the range, the control input generated by the potential function is almost zero, and the steady-state distance is distributed in the range, so that the invention sets the appropriate parameter a according to the tolerance degree of the actual distance deviating from the expected distance.
S05: and calculating the negative gradient of the potential function of each train and the adjacent train to obtain the negative feedback of the trains. In which the direction of the force is represented by a gradient.
In this embodiment, the negative gradient is obtained for the asymmetric adjustable potential function, and the obtained negative feedback of the train is represented as:
wherein, a ij And the communication is shown whether the communication exists between the train i and the train j, if the communication exists, the communication is 1, and if the communication does not exist, the communication is 0.n is the total number of trains in the multi-train system, x i Indicating the location of train i.
When the actual distance is equal to the expected distance, the potential field has the minimum potential energy, if the actual distance is larger or smaller than the expected distance, the artificial potential field generates certain potential energy, and the larger the distance deviation is, the larger the potential energy is. According to the law that the potential energy always changes towards the decreasing direction, the energy of the potential field is continuously decreased until the acting force is 0, so that the potential field in the equilibrium state has the minimum potential energy, and the distance between the columns is stabilized as d r 。
S06: and constructing a control variable of each train, acting on a traction braking system of the train to generate traction or braking force, and controlling the acceleration change of each train, wherein the control variable at least comprises negative feedback of the train based on a train potential function.
The control variables for this embodiment are expressed as:
wherein λ is 1 ，λ 2 May be any selected positive coefficient.
And the resistance of the high-speed train in the running process is overcome. It should be noted that the control variable is a time-dependent parameter, and t is not added to the expression in order to simplify the description herein.
It should be appreciated that controlling the train tracking interval is a key to cooperative control. In the whole operation process, the distance between the trains is always larger than the minimum tracking interval so as to avoid the rear-end collision of the trains. In order to maximize the line carrying capacity, the train tracking interval should not be too large. In actual operation, the train tracking interval often needs to be adjusted according to the speed of the train. When the trains run at a high speed, a large distance between the trains should be maintained to ensure the running safety. When the train speed is reduced, the tracking interval can be properly reduced so as to improve the line traffic capacity. The interval control of the train group is basically represented by the adjustment of the running speed of each train, and the realization of the consistency of the train speed is the basis for ensuring the stability of the tracking interval. When the train group operates in a steady state, the speed of each high-speed train needs to be kept consistent, and the distance between trains is kept unchanged.
Therefore, the present embodiment sets u i1 The aim is to ensure that the speed of the train tracks the desired speed and that the speeds of the trains are consistent.
The deviation between the actual interval and the expected interval of the train is described by means of the artificial function, and the potential energy of the potential function is larger when the deviation is larger; according to the law that the potential energy always changes towards the direction of reduction, a vector in the direction of the negative gradient of the artificial potential function is introduced into a cooperative control strategy, and the tracking interval between control trains tends to an expected value; and the shape of the potential function can be adjusted through parameters, so that the deviation between the steady-state tracking interval and the expected interval is flexibly controlled, and different train control requirements are met. Thus, the present embodiment sets u i2 The method aims to control the distance between adjacent columns based on the adjustable potential function.
In addition to the tractive effort or braking effort generated by the power plant, the high speed train is subject to operational resistance during operation, including both fundamental resistance and additional resistance, and the speed of the high speed train is varied accordingly in response to the combined action of these forces. For this purpose, the present embodiment sets u i3 Indicating overcoming the resistance during train operation.
The dynamic relationship model of the high-speed train adopted in this example is:
wherein x (t) represents the position of the high-speed train at the time t, and v (t) represents the speed of the high-speed train at the time t; u is a control variable, m represents the mass of the high-speed train, c 0 +c 1 v+c 2 v 2 Representing basic running resistance including rolling friction between wheel and rail, sliding friction, friction between bearings of train and air resistance, c 0 ，c 1 ，c 2 Is a constant coefficient.
S07: repeating the steps 1-5 until all trains are operated at a common desired speed and at a stable safe distance from adjacent trains.
It should be noted that, in a specific implementation process, the implementation processes of steps 1 to 5 may be understood as an overall cooperative control method of a multi-train cooperative control system, and how to transmit signals of each train is not restricted, for example, real-time operation information of each train may be directly fed back to other trains or fed back to a control center, and each train may directly generate its own control variable according to the technical idea of the present invention, or the control center generates and feeds back the control variable of each train to each train. According to the technical idea of the invention, the technical idea of the invention can be realized at the angle of each train, that is, each train acquires the real-time running information of the train and the real-time running information of the adjacent trains, and further obtains the control variables of the train per se according to the steps S2 to S5 and controls the control variables. The method comprises the following specific steps:
step S1: the method comprises the steps that a current train acquires real-time running information of the current train and an adjacent train, wherein the real-time running information comprises speed information and position information;
step S2: based on the real-time running information, the current train calculates the distance deviation between the current train and the adjacent train; wherein the distance deviation between adjacent trains represents the actual tracking distance of the train;
and step S3: representing the deviation between the actual tracking distance and the expected safe distance of the train by utilizing the artificial potential field, and further constructing a potential function between the current train and other trains based on the actual tracking distance and the expected safe distance of the train;
wherein the desired safe distance is positively correlated to the actual speed of the train;
and step S4: calculating the negative gradient of the potential function of the current train and the adjacent train to obtain the negative feedback of the train by the current train;
step S5: and constructing a control variable of the current train, acting on a traction braking system of the train to generate traction or braking force, and controlling the acceleration change of the train, wherein the control variable at least comprises negative feedback of the train obtained by the current train based on the negative gradient of the train potential function.
It should be understood that the specific implementation process and the optimization means can refer to the specific contents of the embodiments 1-2, and are not described herein again.
Example 3:
the embodiment provides a system based on a multi-row vehicle collaborative cruise control method, which comprises the following steps: the system comprises a multi-train system, an operation information acquisition subsystem, a train communication subsystem and a control subsystem.
Wherein, multiseriate car system comprises the multiseriate car.
The operation information acquisition subsystem is composed of vehicle-mounted equipment and/or trackside equipment of each train and is used for acquiring real-time operation information of each train.
The train communication subsystem is composed of communication modules and/or wireless block centers of all trains and is used for constructing communication connection between the trains and realizing information transmission between adjacent trains.
The control subsystem is composed of controllers of all trains, is used for obtaining control variables of all trains according to the steps 2-5 or the steps S2-S5 or obtaining control variables of all trains according to the steps 2-5 or obtaining control variables of all trains according to the steps S2-S5, and acts on a traction braking system of the trains to generate traction or braking force so as to control the acceleration change of the trains.
It should be noted that, in some implementation processes, the controller of each train obtains the control variable of each train according to steps 2 to 5 or according to steps S2 to S5, and then generates the corresponding traction or braking force; in other implementation processes, the control center obtains the control variable of each train according to the step 2 to the step 5 or according to the step S2 to the step S5, and then feeds the control variable back to the controller of each train, and then the control variable is used for the traction braking system of the train to generate traction force or braking force.
Example 4:
the present embodiment provides an electronic terminal, which includes: one or more processors, and memory storing one or more computer programs. Wherein the processor invokes the computer program to implement: provided is a multi-train cooperative cruise control method based on a potential function.
It should be understood that the specific implementation process refers to the relevant contents of the embodiments 1-2. The electronic terminal of the embodiment may be a device installed on a train, and is used for generating a control variable of the train; or may be an external device in communication with the train for generating control variables for each train.
The terminal further includes: and the communication interface is used for communicating with external equipment and carrying out data interactive transmission. Such as the collection equipment of the operation information collection subsystem and the communication modules of other trains, so as to obtain the real-time operation information of the train and the adjacent trains.
The memory may include high speed RAM memory, and may also include a non-volatile defibrillator, such as at least one disk memory.
If the memory, the processor and the communication interface are implemented independently, the memory, the processor and the communication interface may be connected to each other via a bus and perform communication with each other. The bus may be an industry standard architecture bus, a peripheral device interconnect bus, an extended industry standard architecture bus, or the like. The bus may be divided into an address bus, a data bus, a control bus, etc.
Optionally, in a specific implementation, if the memory, the processor, and the communication interface are integrated on a chip, the memory, the processor, that is, the communication interface may complete communication with each other through an internal interface.
The specific implementation process of each step refers to the explanation of the foregoing method.
It should be understood that in the embodiments of the present invention, the Processor may be a Central Processing Unit (CPU), and the Processor may also be other general purpose processors, digital Signal Processors (DSPs), application Specific Integrated Circuits (ASICs), field-Programmable Gate arrays (FPGAs) or other Programmable logic devices, discrete Gate or transistor logic devices, discrete hardware components, etc. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like. The memory may include both read-only memory and random access memory, and provides instructions and data to the processor. The portion of memory may also include non-volatile random access memory. For example, the memory may also store device type information.
Example 5:
the present embodiments provide a readable storage medium storing a computer program for invocation by a processor to implement: provided is a multi-train cooperative cruise control method based on a potential function.
It should be understood that the specific implementation process refers to the relevant contents of the embodiments 1-2.
The readable storage medium is a computer readable storage medium, which may be an internal storage unit of the controller according to any of the foregoing embodiments, for example, a hard disk or a memory of the controller. The readable storage medium may also be an external storage device of the controller, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), and the like provided on the controller. Further, the readable storage medium may also include both an internal storage unit of the controller and an external storage device. The readable storage medium is used for storing the computer program and other programs and data required by the controller. The readable storage medium may also be used to temporarily store data that has been output or is to be output.
Based on such understanding, the technical solution of the present invention essentially or partially contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product stored in a storage medium and including instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned readable storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
It should be emphasized that the examples described herein are illustrative and not restrictive, and thus the invention is not to be limited to the examples described herein, but rather to other embodiments that may be devised by those skilled in the art based on the teachings herein, and that various modifications, alterations, and substitutions are possible without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (9)
1. A multi-train cooperative cruise control method based on a potential function is characterized by comprising the following steps:
step 1: acquiring real-time running information of each train in a multi-train system, wherein the real-time running information comprises speed information and position information;
step 2: calculating the distance deviation between each train and other trains based on the real-time running information of each train; wherein the distance deviation between two trains represents the actual tracking distance of the trains;
and 3, step 3: representing the deviation between the actual tracking distance and the expected safe distance of the train by using the artificial potential field, and further constructing a potential function between two trains based on the actual tracking distance and the expected safe distance of the train; wherein the desired safe distance is positively correlated with the actual speed of the train;
and 4, step 4: calculating the negative gradient of the potential function of each train and other trains to obtain the negative feedback of each train;
and 5: constructing a control variable of each train and acting on a traction braking system of the train to generate traction or braking force so as to control the acceleration change of each train, wherein the control variable at least comprises negative feedback of the train obtained based on a train potential function;
wherein the potential function between two trains is represented as:
wherein, U (d) ij ) As a function of the potential between train i and train j,
representing the acting force of the artificial potential field between the train i and the train j on the rear train, a is a positive coefficient,
is the maximum tractive force or the maximum braking force generated by the train traction braking system, d ij Is the distance deviation between train i and train j, d r A desired safe distance.
2. The multi-train cooperative cruise control method according to claim 1, wherein the potential function is an adjustable potential function, a is an adjustable positive coefficient;
adjusting or determining the value of the adjustable positive coefficient according to the allowable deviation degree of the actual tracking distance and the expected safe distance, wherein the larger the allowable deviation degree is, the larger the adjustable positive coefficient is; the smaller the allowed offset, the smaller the adjustable positive coefficient.
3. The multi-train cooperative cruise control method according to claim 1, wherein the potential function is an asymmetric artificial potential function, wherein the corresponding acting force is expressed as:
wherein, a 1 ,a 2 All represent positive coefficientsAnd a is a 2 Greater than a 1 。
4. The multi-train cooperative cruise control method according to claim 1, wherein the negative feedback of a train obtained based on the negative gradient of the potential function of any train with other trains is represented as:
wherein u is i2 Negative feedback for train i; a is a ij Indicating whether communication exists between the train i and the train j, and if communication exists, a ij Is 1, otherwise a ij Is 0; n is the total number of trains in the multi-train system, x i Indicating the position of train i;
if the train i and the train j with communication are adjacent trains, the expected safe distance d r (t)＝v i *h * +d 0 ，d 0 Given a minimum safety distance, h * Given a desired headway, v, between adjacent trains i Is the actual speed of train i;
if the train i and the train j with communication are non-adjacent trains, the expected safe distance d r (t)＝(j-i)(v i *h * +d 0 )。
5. The multi-train cooperative cruise control method according to claim 1, wherein said control variables of the train further comprise control feedback based on a speed deviation of the train, said control feedback being used to control train speed to track a desired speed, expressed as:
wherein u is i1 For control feedback of train i based on speed deviation, m i Is the mass of train i, v i 、v j For train i, trainActual speed of j, v r Is the desired speed of train i; a is ij Indicating whether communication exists between the train i and the train j, and if communication exists, a ij Is 1, otherwise a ij Is 0; n is the total number of trains, alpha, of the multi-train system>0 is a positive coefficient.
6. A multi-train cooperative cruise control method based on a potential function is characterized by being applied to a single train of a multi-train cooperative control system, and comprising the following steps:
step S1: the method comprises the steps that a current train acquires real-time running information of the current train and other trains, wherein the real-time running information comprises speed information and position information;
step S2: based on the real-time running information, the current train calculates the distance deviation between the current train and other trains; wherein the distance deviation between two trains represents the actual tracking distance of the trains;
and step S3: representing the deviation between the actual tracking distance and the expected safe distance of the train by using the artificial potential field, and further constructing a potential function between the current train and other trains based on the actual tracking distance and the expected safe distance of the train; wherein the desired safe distance is positively correlated to the actual speed of the train;
and step S4: calculating the negative gradient of the potential function of the current train and other trains to obtain the negative feedback of the train;
step S5: constructing a control variable of the current train and acting on a traction braking system of the train to generate traction or braking force so as to control the acceleration change of the train, wherein the control variable at least comprises negative feedback of the train obtained by the current train based on the negative gradient of a train potential function;
wherein the potential function between two trains is represented as:
wherein, U (d) ij ) Between train i and train jIs determined by the potential function of (a),
representing the acting force of the artificial potential field between the train i and the train j on the rear train, a is a positive coefficient,
is the maximum tractive effort or the maximum braking effort produced by the train traction brake system, d ij Is the distance deviation between train i and train j, d r A desired safe distance.
7. The system for controlling multiple trains in cooperation with cruise according to any one of claims 1 to 6, comprising: the system comprises a multi-train system, an operation information acquisition subsystem, a train communication subsystem and a control subsystem;
the multi-train system consists of a plurality of trains;
the operation information acquisition subsystem consists of vehicle-mounted equipment and/or trackside equipment of each train and is used for acquiring real-time operation information of each train;
the train communication subsystem is composed of communication modules and/or wireless block centers of all trains and is used for constructing communication connection among the trains and realizing information transmission among the adjacent trains;
and the control subsystem is composed of controllers of all trains and is used for obtaining or acquiring control variables of all trains according to the steps 2-5 or the steps S2-S5 and acting on a traction braking system of the trains to generate traction force or braking force so as to control the acceleration change of the trains.
8. An electronic terminal, characterized by: the method comprises the following steps:
one or more processors;
a memory storing one or more computer programs;
the processor invokes the computer program to implement:
the steps of the multi-train cooperative cruise control method according to any one of claims 1-6.
9. A readable storage medium, characterized by: a computer program is stored, which is invoked by a processor to implement:
the steps of the multi-train cooperative cruise control method according to any one of claims 1-6.
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