A vehicle platooning design method considering packet loss in C-V2X autonomous mode

Abstract

The present invention discloses a vehicle formation design method considering data packet loss in C‑V2X autonomous mode, belonging to the technical field of cellular vehicle networking and intelligent connected vehicles; comprising: firstly, a theoretical analysis model of data packet loss in cellular vehicle networking autonomous mode is proposed, and the relationship between the probability of successful data packet delivery and the vehicle formation vehicle spacing is modeled. Next, the influence of data packet loss on the stability of the vehicle formation queue in the C‑V2X autonomous mode is analyzed, and the threshold expression of the minimum headway time under the condition of ensuring the stability of the vehicle formation queue is derived. Finally, the present invention provides a design strategy for efficient vehicle formations, that is, by increasing the number of leading vehicles communicating with the formation member vehicles and improving the probability of successful data packet delivery, the vehicle formation can reduce the headway time and increase the road capacity.

Description

Technical Field

[0001] The present invention belongs to the technical field of cellular vehicle networking and intelligent networked vehicles, and specifically relates to a vehicle networking formation design method that takes into account data packet loss in a cellular vehicle networking (C-V2X (Cellular-Vehicle to Everything)) autonomous mode. Background Art

[0002] As one of the important application scenarios of autonomous driving, vehicle platooning has significant advantages in alleviating traffic congestion, improving traffic efficiency, improving driving safety and improving fuel economy. A vehicle platoon consists of a group of vehicles with similar motion patterns, usually including a leading vehicle and multiple following vehicles. Each following vehicle in a vehicle platoon needs to follow the vehicle in front and maintain a constant vehicle spacing with the vehicle in front. In order to maintain the stable operation of the vehicle platoon, the member vehicles of the vehicle platoon need to collect the vehicle's motion state information (position, speed, acceleration, etc.) from other platoon members. In early studies, the vehicle's motion state information was obtained through on-board sensors. Due to the limited perception range of on-board sensors such as radar, the platoon member vehicles can only obtain information from the two vehicles closest to them, that is, the front and rear vehicles. With the development of V2X technology, vehicle platoon members can not only exchange information with their two most adjacent vehicles, but also with any number of platoon member vehicles distributed in front of them (not exceeding the size of the queue). Benefiting from V2V communication, vehicle platooning can reduce the headway time, further improve road capacity, and achieve efficient platooning strategies. The communication of vehicle platoons is mainly realized by IEEE 802.11p or cellular vehicle networks. Among them, cellular vehicle networks have attracted extensive attention from academia and industry due to their significant technical advantages such as low latency, high reliability, and flexible working mode integrated with the network, and have gradually become the international mainstream vehicle network communication standard.

[0003] However, packet loss caused by channel attenuation and interference is inevitable in IoV communication, which will affect the stability of vehicle formation. In current research work, the Gilbert-Elliott model is usually used to model the sudden packet loss in IoV communication. In the C-V2X autonomous mode, the 3GPP standard proposes to introduce a distributed resource scheduling algorithm based on semi-persistent scheduling based on perception, allowing vehicles to autonomously reserve radio resources. This distributed resource scheduling algorithm will face packet selection conflict errors and half-duplex transmission errors. The Gilbert-Elliot model cannot accurately describe the packet loss in the C-V2X autonomous mode. In addition, the Gilbert-Elliot model cannot model the relationship between the probability of successful packet delivery and the spacing between vehicles in the formation. Therefore, a theoretical analysis model is needed to characterize the relationship between the probability of successful packet delivery and the spacing between vehicles in the formation in the C-V2X autonomous mode. Furthermore, it is necessary to study the impact of packet loss in the C-V2X autonomous mode on the stability of the vehicle formation queue, derive the expression of the minimum headway under the condition of ensuring the stability of the queue, and provide design guidance for the realization of efficient vehicle formation strategy. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides a vehicle formation design method taking into account data packet loss in a C-V2X autonomous mode to solve the above-mentioned problems.

[0005] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is: a vehicle formation design method considering data packet loss in C-V2X autonomous mode, comprising the following steps:

[0006] S1. Construct a vehicle platoon model for data transmission in the C-V2X autonomous mode;

[0007] S2. Based on the vehicle platoon model, the error types that affect the successful delivery of data packets in the C-V2X autonomous mode are considered, and then a probability model for successful delivery of data packets is established;

[0008] S3. Combining the probability of successful data packet delivery with the criterion for determining the stability of the vehicle platoon, a lemma for determining the stability of the vehicle platoon is constructed;

[0009] S4. According to the lemma for determining the stability of the vehicle formation queue, under the premise of ensuring the stability of the vehicle formation, the minimum threshold expression of the headway of the vehicle formation is calculated, and the vehicle formation design is carried out based on it.

[0010] Furthermore, in the step S1, constructing a vehicle platoon model includes sequentially constructing a vehicle longitudinal dynamics model, designing a spacing strategy and a following strategy for the vehicle platoon, and designing a feedback control law for the vehicle platoon.

[0011] Furthermore, a linear third-order equation is used to describe the kinematic characteristics of the vehicle formation and then construct a vehicle longitudinal dynamics model, which is expressed as follows:

[0012]

[0013] In the formula, p i (t) represents the position of the i-th vehicle at time t, v i (t) represents the speed of the i-th vehicle at time t, a i (t) represents the acceleration of the i-th vehicle at time t, τ represents the time delay constant, and u i (t) represents the control input, represents the derivation of position information, represents the derivative of velocity information, represents the derivative of acceleration information;

[0014] The spacing strategy of the designed vehicle formation is: a constant headway strategy is used to describe the expected spacing between the i-th formation member and the l-th formation member vehicle in front of it, and its expression is:

[0015]

[0016] Where, d i,i-l (t) represents the expected distance d between the i-th train member and the l-th train member car in front of it s represents the expected resting distance, h w represents the headway, v k (t) represents the speed information of the kth platoon member vehicle;

[0017] The designed vehicle formation following strategy is: adopting the multi-front vehicle following mPF strategy, that is, each formation member vehicle can obtain the information of the m formation members in front of it through V2V communication;

[0018] The designed vehicle platoon feedback control law is:

[0019] Considering the delivery status of the data packet, when the number of the preceding vehicle communicating with the i-th member vehicle is 1, the feedback control law is described as:

[0020] u i (t) = -β i,i-1 (t)k a (a i (t)-a i-1 (t))-k v (v i (t)-v i-1 (t))

[0021] -kp (p i (t)-p i-1 (t)+h w v i (t)+d s )

[0022] Considering the delivery status of the data packet, when the number of the preceding vehicles communicating with the i-th member vehicle is greater than 1, the feedback control law is described as:

[0023]

[0024] In the formula, β i,i-1 (t) is a binary variable representing the data packet delivery status between the i-th member car and the i-1-th member car, k a represents the acceleration gain, k v represents the speed gain, k p represents the position gain; where β i,i-1 (t) / β i,i-l (t) is a binary variable representing the data packet delivery status between the i-th member car and the i-1 / il-th member car. When the data packet of the i-1 / il-th member car is successfully received by the i-th member, β i,i-1 (t) / β i,i-l (t) is 1, otherwise, β i,i-1 (t) / β i,i-l (t) value is 0.

[0025] Furthermore, in step S2, the error types that affect the successful delivery of the data packet include resource selection conflict errors P sinr , Half-duplex transmission error P half , the error P caused by the received signal power being lower than the perceived power threshold sen The error P caused by the propagation effect snr ;

[0026] The established probability model for successful data packet delivery for:

[0027]

[0028] Where x represents the transmission distance between the sending end and the receiving end.

[0029] Furthermore, in step S3, the criterion for determining the stability of the vehicle platoon is: E{||H(s)|| ∞}≤1, where H(s) represents the transfer function in the functional formula obtained by taking the mean of both sides and performing Laplace transform on the spacing error control equation for analyzing the impact of data packet loss on the stability of the vehicle formation queue in the cellular vehicle-to-everything (C-V2X) autonomous mode when the number of preceding vehicles m communicating with the i-th formation member vehicle is 1, and E{·} represents taking the mean of it;

[0030] Among them, the spacing error control equation is:

[0031]

[0032] In the formula, e i (t) represents the spacing error, e i (t) = p i (t)-p i-1 (t)+h w v i (t)+d s , It means to find the first-order derivative of the spacing error. It means to find the second-order derivative of the spacing error, It means to find the third-order derivative of the spacing error;

[0033] The function obtained by taking the mean of both sides of the spacing error control equation and performing Laplace transform is:

[0034] Ε{e i (s)}=Ε{H(s)e i-1 (s)}

[0035] In the formula, e i (s) and e i-1 (s) means e i (t) and e i-1 Laplace transform of (t);

[0036] The expression of the transfer function H(s) is:

[0037]

[0038] In the formula, s represents a complex number.

[0039] Furthermore, the lemma for determining the stability of the vehicle platoon is:

[0040] For the formation spacing error system considering packet loss in the C-V2X autonomous mode, the random stability of the vehicle formation is guaranteed when one of the following conditions is met:

[0041] or,

[0042] In the formula, Γ2=k p h w (k v +k p h w )+k v k p h w -k v 2 -2k p , Δ d =Γ2 2 -4Γ1τ, Indicates the probability of successful packet delivery.

[0043] Furthermore, in step S4, when the homogeneous vehicle platooning system using the mPF following strategy (m=1) is adopted, the minimum threshold expression of the headway time to ensure the stability of the vehicle platooning queue is:

[0044]

[0045] Furthermore, in step S4, when a homogeneous vehicle platoon system using the mPF following strategy (m>1) is used, the minimum threshold expression of the headway time to ensure the stability of the vehicle platoon queue is:

[0046]

[0047] The beneficial effects of the present invention are:

[0048] (1) The present invention considers the vehicle platooning scenario in which the C-V2X autonomous mode is used for data transmission. The C-V2X autonomous mode can enable the vehicle platoon to autonomously select resources in a scenario without cellular network coverage.

[0049] (2) The theoretical analysis model proposed in this paper can accurately describe the relationship between the probability of successful data packet delivery and the vehicle platoon spacing in the C-V2X autonomous mode.

[0050] (3) The threshold expression of the minimum headway time under the condition of ensuring the stability of the vehicle formation queue derived by the present invention provides design guidance for realizing an efficient formation strategy, that is, by increasing the number of leading vehicles in communication and improving the probability of successful delivery of data packets, the vehicle formation can reduce the headway time and improve the road capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 A schematic diagram of a vehicle platooning system model based on the C-V2X autonomous mode provided in an embodiment of the present invention.

[0052] Figure 2A flow chart of an analysis method considering the impact of data packet loss on the stability of a vehicle platoon queue provided in an embodiment of the present invention.

[0053] Figure 3 The embodiment of the present invention provides an investigation of the effect of SINR threshold on error probability P under different non-platoon vehicle densities. sinr Impact results diagram.

[0054] Figure 4 The embodiment of the present invention provides an investigation on the effect of SINR threshold on the probability of successful delivery under different transmission distances. Impact results diagram.

[0055] Figure 5 The embodiment of the present invention provides that when m=1 and the headway is greater than the minimum headway threshold h min,1 The result diagram of the vehicle formation spacing error changing with the simulation time

[0056] Figure 6 The embodiment of the present invention provides that when m=1 and the headway is greater than the minimum headway threshold h min,1 The result of the excitation frequency change of the vehicle formation queue stability transfer function when

[0057] Figure 7 The embodiment of the present invention provides that when m=3 and the headway is greater than the minimum headway threshold h min,2 The result diagram of the vehicle formation spacing error changing with the simulation time

[0058] Figure 8 The embodiment of the present invention provides that when m=3 and the headway is greater than the minimum headway threshold h min,2 Result diagram of the change of excitation frequency of the vehicle platoon stability transfer function when . DETAILED DESCRIPTION

[0059] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0060] The system model for analyzing the impact of vehicle platoon stability in the embodiment of the present invention is as follows: Figure 1 As shown by Figure 1It can be seen that, considering a two-lane highway scenario, a vehicle formation consisting of M vehicles is driving on the same lane, and there is a group of non-grouped vehicles driving on the other lane; the vehicle formation includes a group leader and M-1 group member vehicles. Assume that the non-grouped vehicles are modeled as density λ n One-dimensional Poisson point process The C-V2X autonomous mode is used to enable the transmission of data packets within the vehicle formation.

[0061] Based on this, an embodiment of the present invention provides a vehicle formation design method considering data packet loss in a C-V2X autonomous mode. Figure 2 As shown, the following steps are included:

[0062] S1. Construct a vehicle platoon model for data transmission in the C-V2X autonomous mode;

[0063] S2. Based on the vehicle platoon model, the error types that affect the successful delivery of data packets in the C-V2X autonomous mode are considered, and then a probability model for successful delivery of data packets is established;

[0064] S3. Combining the probability of successful data packet delivery with the criterion for determining the stability of the vehicle platoon, a lemma for determining the stability of the vehicle platoon is constructed;

[0065] S4. According to the lemma for determining the stability of the vehicle formation queue, under the premise of ensuring the stability of the vehicle formation, the minimum threshold expression of the headway of the vehicle formation is calculated, and the vehicle formation design is carried out based on it.

[0066] In step S1 of the embodiment of the present invention, a vehicle platoon model is constructed, including sequentially constructing a vehicle longitudinal dynamics model, designing a spacing strategy and a following strategy for the vehicle platoon, and designing a feedback control law for the vehicle platoon.

[0067] Specifically, in this embodiment, a linear third-order equation is used to describe the kinematic characteristics of the vehicle formation and then construct a vehicle longitudinal dynamics model, which is expressed as follows:

[0068]

[0069] In the formula, p i (t) represents the position of the i-th vehicle at time t, v i (t) represents the speed of the i-th vehicle at time t, a i (t) represents the acceleration of the i-th vehicle at time t, τ represents the time delay constant, and u i (t) represents the control input, represents the derivation of position information, represents the derivative of velocity information, represents the derivative of acceleration information;

[0070] In this embodiment, the spacing strategy of the designed vehicle formation is: a constant headway strategy is used to describe the expected spacing between the i-th formation member and the l-th formation member vehicle in front of it, and its expression is:

[0071]

[0072] Where, d i,i-l (t) represents the expected distance d between the i-th train member and the l-th train member car in front of it s represents the expected resting distance, h w represents the headway, v k (t) represents the speed information of the kth platoon member vehicle;

[0073] In this embodiment, the following strategy of the designed vehicle formation is: adopting the multi-front vehicle following mPF strategy, that is, each formation member vehicle can obtain the information of the m formation members in front of it through V2V communication;

[0074] In this embodiment, the designed vehicle formation feedback control law is:

[0075] Considering the delivery status of the data packet, when the number of the preceding vehicle communicating with the i-th member vehicle is 1, the feedback control law is described as:

[0076] u i (t) = -β i,i-1 (t)k a (a i (t)-a i-1 (t))-k v (v i (t)-v i-1 (t))

[0077] -k p (p i (t)-p i-1 (t)+h w v i (t)+d s )

[0078] Considering the delivery status of the data packet, when the number of the preceding vehicles communicating with the i-th member vehicle is greater than 1, the feedback control law is described as:

[0079]

[0080] In the formula, β i,i-1 (t) is a binary variable representing the data packet delivery status between the i-th member car and the i-1-th member car, k a represents the acceleration gain, k v represents the speed gain, kp represents the position gain; where β i,i-1 (t) / β i,i-l (t) is a binary variable representing the data packet delivery status between the i-th member car and the i-1 / il-th member car. When the data packet of the i-1 / il-th member car is successfully received by the i-th member, β i,i-1 (t) / β i,i-l (t) is 1, otherwise, β i,i-1 (t) / β i,i-l (t) value is 0.

[0081] In step S2 of this embodiment, in combination with the perception-based semi-persistent scheduling scheme adopted in the C-V2X autonomous mode, the error types that affect the successful delivery of data packets include resource selection conflict errors P sinr , Half-duplex transmission error P half , the error P caused by the received signal power being lower than the perceived power threshold sen The error P caused by the propagation effect snr ;

[0082] Among them, when the non-group member car and the group member car occupy the same resource block to transmit messages, the SINR of the group member car at the receiving end will be lower than the threshold, that is, a resource selection conflict error occurs. sinr ;

[0083] P sinr (x) = 1-P[SINR>r th ]

[0084] In the formula, r th represents the signal to interference plus noise ratio threshold, SINR represents the signal to interference plus noise ratio;

[0085] P sinr It is closely related to the interference distribution of the member cars of the formation, so the interference distribution of the member cars of the formation is first analyzed with the help of random geometry. The expression of the interference received by the member cars of the formation from the non-formation vehicles is: Among them, P t represents the transmit power, h represents the channel gain, and α represents the path loss factor.

[0086] Performing Laplace transform on the interference, we get:

[0087]

[0088] Combined with the interference Laplace transform, P sinr The expression is:

[0089]

[0090] In the formula, m0 represents the Nakagami constant, n represents the order, represents the lower bound of a normalized gamma random variable with integer parameter m0, x α represents the distance to the power of α, represents the Laplace transform of the interference, P t Indicates the transmit power;

[0091] Error caused by propagation effect P snr Modeled as:

[0092]

[0093] Error P due to half-duplex effect half Modeled as:

[0094]

[0095] Where ε represents the number of data packets transmitted per vehicle per second, and 1000 represents the number of subframes.

[0096] In this embodiment, the probability of successful delivery of data packets between the i-th member car and the i-1-th member car is Described as:

[0097]

[0098] On this basis, considering the types of errors that occur when the above data packets are lost, the probability model of successful data packet delivery is established for:

[0099]

[0100] Where x represents the transmission distance between the sending end and the receiving end.

[0101] In step S3 of the embodiment of the present invention, the criterion for determining the stability of the vehicle platoon is: E{||H(s)|| ∞}≤1, where H(s) represents the transfer function in the functional formula obtained by taking the mean of both sides and performing Laplace transform on the spacing error control equation for analyzing the impact of data packet loss on the stability of the vehicle formation queue in the cellular vehicle-to-everything (C-V2X) autonomous mode when the number of preceding vehicles m communicating with the i-th formation member vehicle is 1, and E{·} represents taking the mean of it;

[0102] Among them, the spacing error control equation is:

[0103]

[0104] In the formula, e i (t) represents the spacing error, ei (t) = p i (t)-p i-1 (t)+h w v i (t)+d s , It means to find the first-order derivative of the spacing error. It means to find the second-order derivative of the spacing error, It means to find the third-order derivative of the spacing error;

[0105] The function obtained by taking the mean of both sides of the spacing error control equation and performing Laplace transform is:

[0106] Ε{e i (s)}=Ε{H(s)e i-1 (s)}

[0107] In the formula, e i (s) and e i-1 (s) means e i (t) and e i-1 Laplace transform of (t);

[0108] The expression of the transfer function H(s) is:

[0109]

[0110] In the formula, s represents a complex number.

[0111] Based on the above criteria for determining the stability of the vehicle platoon, in this embodiment, the lemma for determining the stability of the vehicle platoon is:

[0112] For the formation spacing error system considering packet loss in the C-V2X autonomous mode, the random stability of the vehicle formation is guaranteed when one of the following conditions is met:

[0113] or,

[0114] In the formula, Γ2=k p h w (k v +k p h w )+k v k p h w -k v 2 -2k p , Δ d =Γ2 2 -4Γ1τ, Indicates the probability of successful packet delivery.

[0115] In step S4 of the embodiment of the present invention, based on the above lemma, when a homogeneous vehicle platooning system using the mPF following strategy (m=1) is adopted, the minimum threshold expression of the headway time to ensure the stability of the vehicle platooning queue is:

[0116]

[0117] In step S4 of this embodiment, based on the above lemma, when a homogeneous vehicle platooning system using the mPF following strategy (m>1) is adopted, the minimum threshold expression of the headway time to ensure the stability of the vehicle platooning queue is:

[0118]

[0119] In an embodiment of the present invention, an example of verifying the above-mentioned data packet successful delivery probability model based on the C-V2X autonomous mode is provided, such as Figure 3 and Figure 4 As shown, Figure 3 Explore the effect of SINR threshold on error probability P under different non-platoon vehicle densities sinr The result diagram of the impact. Figure 3 It can be seen that the theoretical analysis results are in good agreement with the simulation results. This shows the accuracy of the proposed theoretical analysis model. In addition, it can be observed that when the SINR threshold is fixed, the increase in the density of non-platooning vehicles will lead to an error probability P sinr This is because as the density of non-platooning vehicles increases, more vehicles try to select resources, which will increase the probability of resource collision, resulting in an error probability P sinr increase. Figure 4 It describes the packet rate P when the transmission distance is 1 times, 2 times, and 3 times the expected vehicle spacing. si,i-l (l=1,2,3) changes with the SINR threshold. The expected inter-vehicle distance (DIPS) of the vehicle formation is set to 15m, and the length of the vehicle is not considered here. It can be seen that when the SINR threshold is fixed, the increase in transmission distance will lead to a decrease in the probability of successful delivery of data packets. Among them, when the SINR threshold is 21.1, the probability of successful delivery of data packets when the transmission distance is 3 times DIPS is 24% and 34% lower than the probability of successful delivery of data packets when the transmission distance is 1 and 2 times DIPS, respectively.

[0120] In the embodiment of the present invention, the minimum threshold of the headway distance to the ground is verified in the homogeneous vehicle formation system of the above two mPF following strategies (m=1 and m>1), as follows: Figures 5 to 8 shown. Figure 5 Describes the situation when m=1 and the headway is greater than the minimum headway threshold h min,1The result diagram of the vehicle formation spacing error changing with simulation time. Figure 5 In the example, it is assumed that the MCS coefficient of the fleet is 17 and the DIPS is 10m, which means that the corresponding probability of successful data packet delivery is 0.82. Figure 5 It can be seen that the spacing error of the vehicle formation decreases as the simulation time increases. Figure 6 Describes the situation when m=1 and the headway is greater than the minimum headway threshold h min,1 The result diagram of the change of excitation frequency of the vehicle platoon stability transfer function when . Figure 6 It can be seen that the platoon stability transfer function is less than 1, indicating that the vehicle platoon is platoon-stable. The above results verify the minimum headway criterion proposed in Theorem 1, that is, when the headway of the vehicle platoon is greater than the minimum headway threshold h min,1 When , the vehicle formation is queue-stable. Figure 7 Describes the situation when the headway between m31 and the vehicle is greater than the minimum headway threshold h min,2 The result diagram of the vehicle formation spacing error changing with simulation time. Figure 7 In the example, it is assumed that the MCS coefficient of the fleet is 17 and the DIPS is 10m, which means that the corresponding probability of successful data packet delivery is 0.82. Figure 7 It can be seen that the spacing error of the vehicle formation decreases as the simulation time increases. Figure 8 Describes the situation when m=3 and the headway is greater than the minimum headway threshold h min,2 The result diagram of the change of excitation frequency of the vehicle platoon stability transfer function when . Figure 8 It can be seen that the platoon stability transfer function is less than 1, indicating that the vehicle platoon is platoon-stable. The above results verify the minimum headway criterion proposed in Theorem 1, that is, when the headway of the vehicle platoon is greater than the minimum headway threshold h min,2 When , the vehicle formation is queue-stable.

[0121] The present invention uses specific embodiments to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

[0122] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific variations and combinations that do not deviate from the essence of the present invention based on the technical revelations disclosed by the present invention, and these variations and combinations are still within the protection scope of the present invention.

Claims

1. A vehicle platoon design method considering data packet loss in C-V2X autonomous mode, characterized in that: The following steps are involved: S1. Construct a vehicle platoon model for data transmission in the C-V2X autonomous mode; S2. Based on the vehicle platoon model, the error types that affect the successful delivery of data packets in the C-V2X autonomous mode are considered, and then a probability model for successful delivery of data packets is established; S3. Combining the probability of successful data packet delivery with the criterion for determining the stability of the vehicle platoon, a lemma for determining the stability of the vehicle platoon is constructed; S4. According to the lemma for determining the stability of the vehicle formation queue, under the premise of ensuring the stability of the vehicle formation, the minimum threshold expression of the headway of the vehicle formation is calculated, and the vehicle formation design is performed based on it; In the step S1, constructing a vehicle formation model includes sequentially constructing a vehicle longitudinal dynamics model, designing a spacing strategy and a following strategy for the vehicle formation, and designing a feedback control law for the vehicle formation; The linear third-order equation is used to describe the kinematic characteristics of the vehicle formation and then construct the vehicle longitudinal dynamics model, which is expressed as follows: In the formula, Indicates i A car in t The location at the moment, Indicates A car in The speed of time, Indicates A car in The acceleration of time, represents the time retardation constant, represents the control input, represents the derivation of the position information, represents the derivative of velocity information, represents the derivative of acceleration information; The spacing strategy of the designed vehicle formation is: using the constant headway strategy to describe the i The first member of the group and the first l The expected spacing between the member cars of a train is expressed as: In the formula, Indicates i The first member of the group and the first l The expected spacing between the train members, represents the expected resting distance, Indicates the headway distance, Indicates k Speed ​​information of each platoon member vehicle; The designed vehicle formation following strategy is: adopting the multi-front vehicle following mPF strategy, that is, each member vehicle of the formation can obtain the information of its front vehicle through V2V communication. m Information of vehicle crew members; The designed vehicle platoon feedback control law is: Considering the delivery status of the data packet, when compared with the i When the number of preceding vehicles in communication between the member vehicles of the marshaling group is 1, the feedback control law is described as: Considering the delivery status of the data packet, when compared with the i When the number of preceding vehicles in communication between the member vehicles of the marshaling group is greater than 1, the feedback control law is described as: In the formula, Indicates The first member car and the i -1 binary variable for the packet delivery status between member vehicles, represents the acceleration gain, represents the speed gain, represents the position gain; where, Representative The first member car and the A binary variable for the packet delivery status between member vehicles. The data packet of the first member car was successfully received by the Members receive, The value of is 1, otherwise, The value is 0.

2. The vehicle formation design method considering data packet loss in C-V2X autonomous mode according to claim 1, characterized in that: In step S2, the error types that affect the successful delivery of the data packet include resource selection conflict errors. , Half-duplex transmission error , the error caused by the received signal power being lower than the perceived power threshold Errors caused by propagation effects ; The established probability model for successful data packet delivery for: In the formula, Indicates the transmission distance between the sending end and the receiving end.

3. The vehicle formation design method considering data packet loss in C-V2X autonomous mode according to claim 1, characterized in that: In step S3, the criterion for determining the stability of the vehicle platoon is: ,in, Indicates that when i The number of preceding vehicles in communication with each member vehicle of the train m When 1 is 1, the transfer function in the functional formula obtained by taking the mean of both sides and performing Laplace transform on the spacing error control equation when analyzing the impact of packet loss on the stability of vehicle formation queues in the cellular vehicle network C-V2X autonomous mode is: It means taking the mean value; Among them, the spacing error control equation is: In the formula, Indicates the spacing error, , It means to find the first-order derivative of the spacing error. It means to find the second-order derivative of the spacing error, It means to find the third-order derivative of the spacing error; The function obtained by taking the mean of both sides of the spacing error control equation and performing Laplace transform is: In the formula, and express and The Laplace transform of Transfer Function The expression is: In the formula, Indicates plural.

4. The vehicle formation design method considering data packet loss in C-V2X autonomous mode according to claim 3 is characterized in that: The lemma for determining the stability of vehicle platooning is: For the formation spacing error system considering packet loss in the C-V2X autonomous mode, the random stability of the vehicle formation is guaranteed when one of the following conditions is met: In the formula, , , , Indicates the probability of successful packet delivery.

5. The vehicle formation design method considering data packet loss in C-V2X autonomous mode according to claim 4, characterized in that: In step S4, when a homogeneous vehicle platoon system using the mPF following strategy (m=1) is used, the minimum threshold expression of the headway time to ensure the stability of the vehicle platoon queue is: 。 6. The vehicle formation design method considering data packet loss in C-V2X autonomous mode according to claim 4, characterized in that: In step S4, when a homogeneous vehicle platooning system using the mPF following strategy (m>1) is used, the minimum threshold expression of the headway time to ensure the stability of the vehicle platooning queue is: 。

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