1. A personalized self-adaptive track prediction method based on driving style and intention is characterized by comprising the following steps:

s1, classifying the driving style;

s2, recognizing the driving intention: based on longitudinal speed change, transverse lane changing direction and lane changing action, dividing into 9 driving intentions in three dimensions, namely deceleration left lane changing, constant speed left lane changing, acceleration left lane changing, deceleration straight going, constant speed straight going, acceleration straight going, deceleration right lane changing, constant speed right lane changing and acceleration right lane changing;

s3, missing data padding: estimating missing data by using an LSTM network;

s4, trajectory prediction: and (4) adopting an LSTM network to predict the track.

2. The personalized adaptive trajectory prediction method based on driving style and intention as claimed in claim 1, wherein said step S1 comprises the steps of:

s11, selecting characteristic parameters of driving style evaluation: averaging the travel coefficients of a vehicle in a time windowAnd average braking coefficientAs characteristic parameters, used for classification of driving style;

s12, determining the number of driving style classifications: carrying out cluster analysis on a training sample x by utilizing a K-means algorithm, dividing the training sample into K clusters, namely K driving styles, wherein x is a two-dimensional vector

Selecting the contour coefficient S as an evaluation index:

wherein a is the similarity of the sample and other samples in the cluster where the sample is located, and is equal to the average distance between the sample and all the samples in the same cluster; b is the similarity of the sample to the samples in other clusters, equal to the average distance between the sample and all points in the nearest cluster; respectively calculating contour coefficients under different K values, and finally selecting the K value corresponding to the contour coefficient S reaching the maximum value as the classification number of the driving style;

s13, calibrating a driving style label for the data set: performing cluster analysis on the training samples according to the optimal K value, and calibrating the driving style of the vehicle in the training samples by using a clustering result;

s14, training and obtaining a driving style classification model: and training the SVM classifier by using the training sample with the driving style label to obtain a driving style classification model.

3. The method for predicting the personalized adaptive trajectory based on the driving style and the intention as claimed in claim 1, wherein the step S2 is implemented by:

s21, calibrating the driving intention of the data set: traversing the collected data set, searching vehicles with changed lanes, and recording timestamps of the changed lanes; determining the stage between the starting point and the end point of the intention switching of the vehicle with changed lane according to the lateral speed of the vehicle and the change condition of the lane offset: and calibrating the driving intention data in the data set;

s22, selecting characteristic parameters of driving intention recognition: selecting a transverse speed change rate, a longitudinal speed change rate and a lane transverse offset of the vehicle as characteristic parameters for recognizing the driving intention;

and S23, taking the transverse speed change rate, the longitudinal speed change rate and the lane transverse offset of the vehicle as input data, training a random forest and finally obtaining a driving intention recognition model.

4. The method for predicting the personalized adaptive trajectory based on the driving style and the intention as claimed in claim 1, wherein the step S4 is implemented by: the input of the LSTM network is a time sequence list of driving style, driving intention and position information in a track prediction period T on surrounding vehicles; introducing an Attention mechanism between an LSTM layer and a full connection layer, inputting the output of a hidden layer of the LSTM layer at all times into an Attention layer, distributing different weights to the hidden layer, weighting and summing to obtain a new output vector, and then converting the output shape through the full connection layer; the LSTM finally outputs a position information time sequence table for predicting the next track prediction period of the surrounding vehicles, if the driving data of the surrounding vehicles are not received in time in the next track prediction period, the position information time sequence of the track prediction period is filled according to the time point correspondence, and the driving style and the driving intention adopt the data value of the previous track prediction period;

and (3) determining a track prediction period T by adopting a constraint optimization method: by usingIndicating a vehicle v_iFor attention set V_iAny vehicle v_jCalculating the required amount of the force,denotes v_iCalculating total demand for surrounding vehicle attention sets in a period T, wherein M is the calculation power limit of the vehicle;the calculation resource utilization ratio in the track prediction period T is represented, and A is the track prediction accuracy; meanwhile, the degree of attention to the calculation power demand and the prediction accuracy is controlled using α and β as weights, where α ∈ [0, 1]，β∈[0，1]，α+β＝1；

In the constraint condition, Q is the minimum limit of the prediction accuracy, the track prediction accuracy needs to be more than or equal to Q, and v is within the period time T_iThe total calculation demand of the surrounding vehicle attention set is required to be smaller than the self calculation power limit M of the vehicle;

and the final objective function is the ratio of the calculation resource utilization ratio multiplied by the calculation resource weight alpha to the trajectory prediction precision multiplied by the precision weight beta, and finally, one-dimensional search is carried out in a feasible domain along a certain direction to seek the optimal solution T:

s.t.A≥Q，A∈[0，1]，Q∈[0，1]

Background

In recent years, global positioning technology has been rapidly developed and widely used in intelligent transportation systems. Meanwhile, prediction of future trajectories of surrounding vehicles in advanced driving assistance systems is one of the key directions of current research. Since autonomous vehicles inevitably interact frequently with other traffic participants during actual road driving, the driving strategy planning of autonomous vehicles is closely related to the driving behavior of surrounding vehicles. To ensure safe driving in dynamically changing traffic environments, autonomous vehicles need to have the ability to predict the evolution of future traffic conditions, especially the future trajectory of surrounding vehicles. A vehicle equipped with a Global Positioning System (GPS) can locate its own position in real time, sense surrounding vehicles through sensors, and communicate and exchange vehicle travel data through an internet of vehicles technology. Meanwhile, due to the increasing data volume and computer computing power, a track prediction algorithm taking data as a drive becomes possible. Thus, the autonomous vehicle can predict the traveling trajectory of the surrounding vehicle for a future period of time based on the sensed and communicated data.

In current research and applications, trajectory prediction techniques also face the following challenges:

first, the driving style of the driver may be different due to different characteristics of driving experience, age, character, etc., and different driving styles may show different driving behaviors. For example, a driver of the plunging type may frequently overtake, and thus the vehicle trajectory is curved, and driving behaviors with large changes in vehicle speed, such as rapid acceleration and rapid deceleration, are likely to occur; the stable driver has a relatively flat driving track, and the vehicle speed is relatively uniform. If the single track prediction model is used for predicting the tracks of all running vehicles, the problem of low accuracy is inevitably caused.

Second, road geography, traffic regulations, and traffic signals may constrain the driver's driving intent, such as keeping straight, turning left, turning right, changing lanes left, and changing lanes right. The driving intention characterizes the subsequent driving tendency of the driver, and the driving tendency plays an important role in the future driving track prediction.

Finally, in a dense Vehicle Communication network under 5G (5th Generation Mobile Communication Technology, 5G) based Vehicle-to-Vehicle (V2V) Communication Technology, due to the influence of urban obstacle obstruction, extreme weather, frequency reuse, and other factors, the autonomous Vehicle may not be able to timely acquire or perceive all the driving data of surrounding vehicles within a specified time. Therefore, extra measures are required to guarantee the track prediction accuracy under incomplete data.

Therefore, aiming at the problem of current vehicle track prediction, a personalized self-adaptive track prediction method based on the driving style and the intention is designed, on one hand, the driving track of surrounding vehicles in a period of time in the future is predicted in a personalized mode through the driving style and the driving intention, on the other hand, missing data are estimated and filled, the track prediction accuracy is improved, the safety of an automatic driving vehicle is improved, and the method has important significance.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, and provides a driving style and intention-based personalized adaptive track prediction method which considers personalized driving behaviors of different drivers by judging driving styles and identifying driving intentions, and realizes prediction accuracy guarantee under the condition of incomplete data by a missing data prediction and prediction method, so that personalized adaptive track prediction is realized, and the track prediction accuracy is improved.

The purpose of the invention is realized by the following technical scheme: a personalized self-adaptive track prediction method based on driving style and intention comprises the following steps:

s1, classifying the driving style;

s2, recognizing the driving intention: based on longitudinal speed change, transverse lane changing direction and lane changing action, dividing into 9 driving intentions in three dimensions, namely deceleration left lane changing, constant speed left lane changing, acceleration left lane changing, deceleration straight going, constant speed straight going, acceleration straight going, deceleration right lane changing, constant speed right lane changing and acceleration right lane changing;

s3, missing data padding: estimating missing data by using an LSTM network;

s4, trajectory prediction: and (4) adopting an LSTM network to predict the track.

Further, the step S1 includes the following steps:

s11, selecting characteristic parameters of driving style evaluation: averaging the travel coefficients of a vehicle in a time windowAnd average braking coefficientAs characteristic parameters, used for classification of driving style;

s12, determining the number of driving style classifications: carrying out cluster analysis on a training sample x by utilizing a K-means algorithm, dividing the training sample into K clusters, namely K driving styles, wherein x is a two-dimensional vector

Selecting the contour coefficient S as an evaluation index:

wherein a is the similarity of the sample and other samples in the cluster where the sample is located, and is equal to the average distance between the sample and all the samples in the same cluster; b is the similarity of the sample to the samples in other clusters, equal to the average distance between the sample and all points in the nearest cluster; respectively calculating contour coefficients under different K values, and finally selecting a value corresponding to the contour coefficient S reaching the maximum value as a classification number of the driving style;

s13, calibrating a driving style label for the data set: performing cluster analysis on the training samples according to the optimal K value, and calibrating the driving style of the vehicle in the training samples by using a clustering result;

s14, training and obtaining a driving style classification model: and training the SVM classifier by using the training sample with the driving style label to obtain a driving style classification model.

Further, the specific implementation method of step S2 is as follows:

s21, calibrating the driving intention of the data set: traversing the collected data set, searching vehicles with changed lanes, and recording timestamps of the changed lanes; determining the stage between the starting point and the end point of the intention switching of the vehicle with changed lane according to the lateral speed of the vehicle and the change condition of the lane offset: and calibrating the driving intention data in the data set;

s22, selecting characteristic parameters of driving intention recognition: selecting a transverse speed change rate, a longitudinal speed change rate and a lane transverse offset of the vehicle as characteristic parameters for recognizing the driving intention;

and S23, taking the transverse speed change rate, the longitudinal speed change rate and the lane transverse offset of the vehicle as input data, training a random forest and finally obtaining a driving intention recognition model.

Further, the specific implementation method of step S4 is as follows: the input of the LSTM network is a time sequence list of driving style, driving intention and position information in a track prediction period T on surrounding vehicles; introducing an Attention mechanism between an LSTM layer and a full connection layer, inputting the output of a hidden layer of the LSTM layer at all times into an Attention layer, distributing different weights to the hidden layer, weighting and summing to obtain a new output vector, and then converting the output shape through the full connection layer; the LSTM finally outputs a position information time sequence table for predicting the next track prediction period of the surrounding vehicles, if the driving data of the surrounding vehicles are not received in time in the next track prediction period, the position information time sequence of the track prediction period is filled according to the time point correspondence, and the driving style and the driving intention adopt the data value of the previous track prediction period;

and (3) determining a track prediction period T by adopting a constraint optimization method:

first, the objective function is to pursue more prediction accuracy and less computational power requirementsIndicating a vehicle v_iFor attention set V_iAny vehicle v_jCalculating the required amount of the force,denotes v_iCalculating total demand for surrounding vehicle attention sets in a period T, wherein M is the calculation power limit of the vehicle;the calculation resource utilization ratio in the track prediction period T is represented, and A is the track prediction accuracy; meanwhile, the degree of attention to the calculation power demand and the prediction accuracy is controlled using α and β as weights, where α ∈ [0, 1]，β∈[0，1]，α+β＝1；

In the constraint condition, Q is the minimum limit of the prediction accuracy, the track prediction accuracy needs to be more than or equal to Q, and v is within the period time T_iThe total calculation demand of the surrounding vehicle attention set is required to be smaller than the self calculation power limit M of the vehicle;

and the final objective function is the ratio of the calculation resource utilization ratio multiplied by the calculation resource weight alpha to the trajectory prediction precision multiplied by the precision weight beta, and finally, one-dimensional search is carried out in a feasible domain along a certain direction to seek the optimal solution T:

s.t.A≥Q，A∈[0，1]，Q∈[0，1]

the invention has the beneficial effects that: according to the method, on one hand, the individualized driving behaviors of different drivers are considered by judging the driving style and identifying the driving intention, on the other hand, the prediction accuracy guarantee under the condition of incomplete data is realized by a missing data prediction and prediction method, and the automatic driving vehicle can be efficiently assisted to move, so that the application field of the method is expanded.

The invention designs a personalized self-adaptive track prediction method based on driving style and intention, aiming at the problem that when an automatic driving vehicle predicts the future driving track of a peripheral networked vehicle under the background of Internet of vehicles, the personalized driving behavior of a driver and incomplete communication data due to frequency multiplexing interference are ignored. The system can analyze and process the acquired data information through communication with surrounding vehicles and roadside units in the driving process, and on one hand, individualized driving behaviors of different drivers are considered through judging the driving style and recognizing the driving intention; on the other hand, the prediction accuracy guarantee under the condition of incomplete data is realized through a missing data prediction and prediction method, so that the personalized self-adaptive track prediction is realized, the track prediction accuracy is improved, and the safety of the automatic driving vehicle is improved.

Drawings

FIG. 1 is a schematic diagram of an urban Internet of vehicles traffic network architecture;

FIG. 2 is a flow chart of a method for personalized adaptive trajectory prediction in accordance with the present invention;

FIG. 3 is a schematic view of the driving style sliding assessment classification according to the present invention;

FIG. 4 is a schematic view illustrating a driving intent switch manner according to the present invention;

FIG. 5 is a block diagram of the personalized adaptive trajectory prediction based on driving style and intent of the present invention;

FIG. 6 is a block diagram of the attention mechanism of the present invention in combination with an LSTM.

Detailed Description

As shown in fig. 1, in a future urban intelligent transportation system, a Road Side Unit (RSU) and an On Board Unit (OBU) which carry 5G Vehicle-to-outside (Vehicle to evolution, V2X) technologies together construct a Vehicle-to-Road network coordination system, and direct communication between V2V and a Vehicle-to-Road (Vehicle to RSU, V2R) is realized through a 5G-V2X communication protocol. At the same time, the RSU may also send a query request (RSU to CN, R2C) to a remote server through a Core Network (CN). The vehicle-mounted sensing and vehicle-mounted sensing are combined, and various sensors finish collecting traffic information such as vehicles, roads and environments together, so that intelligent cooperation and cooperation between the vehicles and infrastructure can be realized, and safe and reliable automatic driving of vehicle-road cooperation can be realized while severe weather, same frequency interference and other conditions are met.

Assuming that the total number of vehicles in the system is N, a certain autonomous vehicleThe license plate number can be uniquely identified, and the license plate number can be known by the system in modes such as camera identification and the like and can be informed to surrounding vehicles. For convenience of presentation, the invention uses v as it stands_iEquivalent to its license plate number as the unique identification of the car. v. of_iPeripheral vehicles can be sensed through vehicle-mounted sensors, and surrounding vehicles of interest are selected to form v_iAttention set V of_i＝{v_jI j belongs to {1, …, N }, j ≠ i }. The attention set can be selected according to the practical application environment, for example, based on the communication radius, the vehicles in the communication range belong to the attention set. v. of_iAny vehicle v with whom attention is focused_jAnd the communication protocol is achieved, and the driving data is periodically exchanged in a V2V communication mode.

The invention utilizes various driving data collected by an urban intelligent traffic system aiming at running vehicles and takes the driving data as an experimental data set. Selection after analysis Using principal component analysisTaking driving indexes such as speed, acceleration, following time interval and the like in the data set as characteristic parameters, clustering the drivers in the data set into K styles by using a K-means clustering method, and respectively representing the styles as g₀，…，g_K. As in a certain application scenario, the clustering result K is 3, and g₁When it is assumed that g is a progressive type₀＝g₂Stable form, g₃Is conservative, wherein g₀As a default driving style. And labeling the driving style of the vehicle in the data set according to the clustering result. Next, a Support Vector Machine (SVM) is trained using the labeled data set, thereby deriving a classification model of the driving style. Driving intention p_mThe driving intention representing the driving demand of the driver is divided into 9 classes, p respectively, based on speed change, lane changing direction and lane changing action by combining with actual urban traffic conditions₀Left lane change at deceleration, p₁Left lane changing at constant speed, p₂Acceleration left lane change, p₃Deceleration straight-line, p₄I.e. straight going at constant speed, p₅Acceleration straight, p₆Speed reduction right lane change, p₇Equal right lane change sum p₈And (3) calibrating the driving intention of the vehicle according to the transverse speed and lane offset change of the vehicle, and learning the data set with the driving intention by adopting a random forest algorithm to finally obtain a driving intention recognition model.

And finally, predicting the future driving track of the surrounding vehicle by using a Long Short-Term Memory (LSTM) network, wherein the prediction result can be used as a filling candidate of missing data, more attention, namely right, is replayed on a real obtained value by combining an attention mechanism, less attention is paid to a predicted value for filling, the integrity of input data in the next track prediction period can be ensured, and the track prediction of the surrounding vehicle is completed at the same time. The technical scheme of the invention is further explained by combining the attached drawings.

As shown in fig. 2, the personalized adaptive trajectory prediction method based on driving style and intention of the present invention includes the following steps:

s1, classifying the driving style;

in the past, research and determination of driving style have mainly focused on research methods based on questionnaires. With the development of automobile intellectualization, researchers have proposed an objective measurement method based on real vehicle experimental data. Actually, there is no accurate standard for the classification of the driving style, and many scholars construct a driving style classification mechanism by objective vehicle parameters, thereby achieving a more objective and rigorous judgment of the driving style of the driver. The driving style has great influence on the driving safety and stability, and the driving style is used for evaluating the driving acceleration of a driver in the method, namely reflecting the impact degree of the driver on the speed, thereby playing an important role in intelligent transportation and vehicles. The driving behavior characteristics are extracted from the driving data to objectively describe the driving acceleration, and drivers with different driving acceleration have large difference in speed and acceleration, so that the speed and the acceleration are characteristic indexes representing the driving style. Since the collected driving parameter characteristic quantities are a series of continuous time series data, it is necessary to convert these data into a plurality of characteristic variables. Many studies discretize them according to their statistical values of standard deviation, mean, maximum, etc., in the present method a travel coefficient is definedAnd coefficient of brakingA in the traveling coefficient is an arbitrary constant larger than 0, a in the braking coefficient is an arbitrary constant smaller than 0, and v is the vehicle speed. And finally, adopting the average traveling coefficient and the average braking coefficient as characteristic variables of the driving style classification.

The driving style is not instantaneous motion characteristics but is accumulated over a period of time, so a time window is used to classify the driving style. First, when the vehicle v is automatically driven_iAttention set V of_iA certain vehicle v of interest_jWhen it first appears in the area, v_jDriving style of (a) is default g₀. Subsequent driving in the cumulative time window WThe evaluation and classification of style, and the time window moves the observation evaluation over time to account for changes in driving style due to weather, traffic conditions, driver switches, etc. A schematic diagram of the slip evaluation classification of the specific driving style is shown in fig. 3.

The K-means algorithm is a commonly used clustering algorithm, measures the similarity between samples by adopting distances, and can divide a sample set into K clusters, namely a cluster C_iMean vector of

Wherein x is a two-dimensional vector

Is the centroid of the cluster. The purpose of the K-means algorithm is to find K centroids to minimize the squared error.

A smaller squared error E indicates a higher similarity of samples within a cluster.

The driving style classification in the invention specifically comprises the following steps:

s11, selecting characteristic parameters of driving style evaluation: averaging the travel coefficients of a vehicle in a time windowAnd average braking coefficientAs characteristic parameters, used for classification of driving style;

s12, determining the number of driving style classifications: carrying out cluster analysis on a training sample x by utilizing a K-means algorithm, dividing the training sample into K clusters, namely K driving styles, wherein x is a two-dimensional vector

The K-Means algorithm is an unsupervised clustering algorithm and is a common clustering method. Clustering a cluster C in a clustering process_iMean vector mu of_iAs the centroid of the cluster:

wherein x is a two-dimensional vector

Clustering is carried out;

the contour coefficient s (silouette score) was selected as an evaluation index:

wherein a is the similarity of the sample and other samples in the cluster where the sample is located, and is equal to the average distance between the sample and all the samples in the same cluster; b is the similarity of the sample to the samples in other clusters, equal to the average distance between the sample and all points in the nearest cluster; respectively calculating contour coefficients under different K values, and finally selecting a value corresponding to the contour coefficient S reaching the maximum value as a classification number of the driving style; for example, K is taken from 1 to 10 to perform clustering respectively, then the contour coefficients are calculated respectively, and finally the corresponding K value when the contour coefficients reach the maximum value is selected as the classification number of the driving style, because the contour coefficients increase first and then decrease with the increase of K, if K is 10, the contour coefficients do not decrease, K can be linearly increased again until the contour coefficients reach the K value;

s13, calibrating a driving style label for the data set: performing cluster analysis on the training samples according to the optimal K value, and calibrating the driving style of the vehicle in the training samples by using a clustering result;

s14, training and obtaining a driving style classification model: and training the SVM classifier by using the training sample with the driving style label to obtain a driving style classification model.

S2, recognizing the driving intention: the lane change intention of the driver is recognized, and important driving trend information can be provided for future driving track prediction. In general, the lane-change intention recognition method may be classified into two types: a prediction based on predicted driver behavior data and based on vehicle trajectory data. At the driver level, we test the driver's facial expression information and body movements mainly through a camera mounted in front of the driver, and then analyze the driver's features before the lane change process, which is suitable for predicting the intention of the ego-vehicle. In fact, the lane change process is a continuous process with a temporal characteristic, which means that the driving state of the vehicle is characterized by continuity. Therefore, in the present invention, we can analyze the traveling trajectory data of surrounding vehicles to predict the intention of lane change.

The lane change of the vehicle means that the vehicle does not collide when running from a current lane to an adjacent lane, wherein the lateral position offset and the lateral speed change rate of the vehicle are changed. Based on longitudinal speed change, transverse lane changing direction and lane changing action, the three dimensions are divided into 9 driving intentions, namely deceleration left lane changing, uniform speed left lane changing, acceleration left lane changing, deceleration straight going, uniform speed straight going, acceleration straight going, deceleration right lane changing, uniform speed right lane changing and acceleration right lane changing, and a schematic diagram of a specific driving style switching mode is shown in fig. 4; to create a lane change training data set and a test data set, we need to select a vehicle with lane change behavior and determine its corresponding lane change start and end points.

The random forest algorithm is a statistical learning theory based on a traditional decision tree, and the basic thought is as follows: (1) selecting k groups of data from the initial sample set by using a resampling sampling method, wherein the capacity of each group of data is the same as that of the initial sample set; (2) respectively establishing k decision tree models for the k groups of data, and calculating corresponding classification results; (3) voting is carried out according to the k classification results to determine the final classification. Since the vehicle lane change intention is divided based on three dimensions of speed change, lane change direction and lane change action, the random forest algorithm is adopted to identify the vehicle lane change intention, and the classification effect is higher in accuracy. The random forest is an algorithm for integrating a plurality of trees by the idea of ensemble learning, and the basic unit of the random forest is a decision tree. Each decision tree is randomly sampled to obtain a data set for training, and problems can be classified from multiple dimensions due to different specific features of each tree. The whole tree is continuously constructed from the root node in the decision tree, the root node is constructed at the beginning, all training data are placed in the root node, an optimal characteristic is selected, the training set is divided into subsets according to the characteristic, and when the subsets can be correctly classified, leaf nodes are constructed. According to the information gain criterion in the process of feature segmentation of the subsets, the change of information before and after the clustering of the partition columns is called information gain, namely the information entropy of a parent node is subtracted by the information entropy of all child nodes. The entropy is defined as the expected value of the information, and the expression of the information entropy is

Where p (i | t) represents the probability that node t is classified as i. The information gain is thus expressed as

Wherein D is a parent node, D_iIs a child node, and a in Gain (D, a) is selected as the attribute of the D node.

In the invention, the specific implementation method of the driving intention recognition is as follows:

s21, calibrating the driving intention of the data set: traversing the collected data set, searching vehicles with changed lanes, and recording timestamps of the changed lanes; determining the stage between the starting point and the end point of the intention switching of the vehicle with changed lane according to the lateral speed of the vehicle and the change condition of the lane offset: and calibrating the driving intention data in the data set;

s22, selecting characteristic parameters of driving intention recognition: the transverse speed change rate, the longitudinal speed change rate and the lane transverse offset of the vehicle respectively represent the longitudinal speed change, the transverse lane changing action and the lane changing direction, and the process of dynamic change of the driving intention of a driver can be visually represented. Therefore, the transverse speed change rate, the longitudinal speed change rate and the lane transverse offset of the vehicle are selected as characteristic parameters for recognizing the driving intention;

and S23, taking the transverse speed change rate, the longitudinal speed change rate and the lane transverse offset of the vehicle as input data, training a random forest and finally obtaining a driving intention recognition model.

S3, missing data padding: estimating missing data by using an LSTM network; due to the influence of factors such as urban barrier shielding, extreme weather and frequency reuse, the automatic driving vehicle cannot obtain complete data of surrounding vehicles in time through self perception and wireless communication. Therefore, measures are required to guarantee the track prediction accuracy under incomplete data.

The data missing mode mainly comprises the following steps: univariate and multivariate deletions. In the scenario of the patent, since one data packet includes all the driving data of a certain vehicle at the time, when data loss occurs, all the driving parameter data at the time are lost, and the loss has randomness. In practical application, as for a filling mode of missing data, one is to analyze statistical characteristics of data in the neighborhood of the missing data and then fill the data with the characteristics. The filling algorithm using the mean, mode and cluster adopts the missing data filling idea. Another way to fill in missing data is to analyze the overall changing characteristics of the data, for example, an LSTM network is used to fill in the missing data, and most of the data using this filling scheme has a timing characteristic. Because the missing data in the method are all the driving data of the vehicle, the method has strong time sequence characteristics, and therefore the LSTM network is adopted to estimate the missing data.

The LSTM network responsible for the trajectory prediction predicts the travel position data of the traveling vehicle in the next trajectory prediction period within the present trajectory prediction period. When the traveling position data of the next track prediction period is missing, the missing data can be filled by using the prediction result. However, the predicted data always has errors, so that the integrity of the input data of the track prediction model can be realized by combining an attention mechanism in the LSTM of the track prediction, reproducing more weight on a real value and putting less weight on a filled predicted value. Meanwhile, it is assumed that the driving style and the driving intention do not change in a short time (one trajectory prediction period), and thus if it is not sufficient to judge the driving style and the driving intention due to data loss, the driving style and the driving intention of the previous trajectory prediction period are employed.

S4, trajectory prediction: the trajectory prediction technique is based on the above driving style classification, driving intent recognition, and missing data filling. A specific block diagram is shown in fig. 5.

LSTM is a variant of the Recurrent Neural Network (RNN). In order to solve the problem of RNN gradient disappearance, the hidden layer unit of RNN is replaced by an LSTM storage unit comprising 3 gates (an input gate, a forgetting gate and an output gate), and the blocks enable the weight of self-circulation to change by increasing the input threshold, the forgetting gate and the output threshold, and the integral scale at different moments can be dynamically changed under the condition that the model parameters are fixed. Because the hidden layer of the time sequence data processing device adds a feedback structure, namely, the output at the moment is not only related to the input at the moment, but also related to the output at the last moment, and the time sequence data processing device is equivalent to a deep neural network which is expanded on a time sequence, so that the time sequence data processing device is more suitable for processing time sequence data. Therefore, the invention uses the LSTM network to predict the trajectory time series.

In the present invention, the inputs to the LSTM network are a time sequence table of driving style, driving intent, and location information within one track prediction period on the surrounding vehicle. In order to make the weight occupied by the real value larger and the weight occupied by the predicted value smaller, an attention mechanism is introduced on the basis of the LSTM, and a specific combination structure is shown in FIG. 6. In a conventional LSTM4 network, only the hidden layer output at the last moment is usually passed to the fully-connected layer, which may cause inaccuracy of the information passed to the fully-connected layer due to instability of the accuracy of the input data caused by the missing data. The improved algorithm makes full use of the output information at each instant by introducing a mechanism of attention between the LSTM layer and the fully connected layer. The output of the hidden layer at all times of the LSTM layer is input into the Attention layer, different weights are distributed to the hidden layer, a new output vector is obtained through weighted summation, and then the output shape is converted through a fully connected layer (Dense), so that the prediction performance of the model is improved. The LSTM will eventually output a time-ordered list of location information that predicts the next trajectory prediction period for the surrounding vehicle. If the driving data of surrounding vehicles are not received in time in the next track prediction period, the position information time sequence of the track prediction period is filled according to the time point, and the driving style and the driving intention adopt the data value of the previous track prediction period, so that the completeness of the data is realized.

The period length of the trajectory prediction can affect the prediction accuracy and the computational demand, for example: the shorter the track prediction period is, the higher the prediction accuracy is, but the calculation is frequent, and the calculation power is more. Therefore, a reasonable track prediction period needs to be determined to balance the track prediction accuracy and the computational demand.

The invention adopts a constraint optimization method to determine a track prediction period T:

first, the objective function is to pursue more prediction accuracy and less computational power requirementsIndicating a vehicle v_iFor attention set V_iAny vehicle v_jCalculating the required amount of the force,denotes v_iCalculating total demand for surrounding vehicle attention sets in a period T, wherein M is the calculation power limit of the vehicle;the calculation resource utilization ratio in the period T is represented, and A is the accuracy of the track prediction; meanwhile, the degree of attention to the calculation power demand and the prediction accuracy is controlled using α and β as weights, where α ∈ [0, 1]，β∈[0，1]，α+β＝1；

In the constraint condition, Q is the minimum limit of the prediction accuracy, and can be determined according to the requirement in practical application, so that the trajectory prediction accuracy needs to be more than or equal to Q, and v is within the period time T_iThe total calculation demand of the surrounding vehicle attention set is required to be smaller than the self calculation power limit M of the vehicle;

and the final objective function is the ratio of the calculation resource utilization ratio multiplied by the calculation resource weight alpha to the trajectory prediction precision multiplied by the precision weight beta, and finally, one-dimensional search is carried out in a feasible domain along a certain direction to seek the optimal solution T:

s.t.A≥Q，A∈[0，1]，Q∈[0，1]

it will be appreciated by those of ordinary skill in the art that the embodiments described herein are intended to assist the reader in understanding the principles of the invention and are to be construed as being without limitation to such specifically recited embodiments and examples. Those skilled in the art can make various other specific changes and combinations based on the teachings of the present invention without departing from the spirit of the invention, and these changes and combinations are within the scope of the invention.