Vehicle trajectory prediction plays a crucial role in ensuring the driving safety of autonomous vehicles in complex traffic scenes. To accurately predict the trajectory of autonomous vehicles, in this article, we propose a distributed decouple long short-term memory (LSTM) self-trajectory prediction method for autonomous driving. The proposed new recurrent network includes a decouple-LSTM unit and corresponding distributed network architecture. To characterize the closed-loop dynamics of autonomous vehicles, a decouple gate and a control gate are proposed to build the decouple-LSTM unit. The data are processed in different ways according to whether the data participates in the recurrent. The decouple gate filters the data participating in the recurrent, while the control gate handles the data outside the recurrent. By leveraging the decouple-LSTM unit, a distributed network architecture is established, which corresponds with the general vehicle motion control architecture, which effectively models the vehicle motion processes. The proposed method is trained using an actual vehicle dataset and validated through vehicle experiments. The prediction horizon ranges from 0.5 to 3 s. When the prediction horizon is set to 3 s, compared with the LSTM method, the mean square error of the proposed method decreases by 98.0%. Results show that the proposed method significantly improves vehicle trajectory prediction accuracy.

For automated driving vehicles, trajectory planning is responsible for obtaining feasible trajectories with velocity profiles according to driving environments. From the perspective of trajectory planning, multiple uncertainties of environments and tracking deviations are two significant factors affecting driving safety. The former disturbs the judgment of trajectory planning on the environments, and the latter reduces the tracking accuracy of planned trajectories. To solve these problems, an improved model predictive control (MPC) trajectory planning method is proposed in this paper. Firstly, a Kalman filter fusion method is carried out to predict obstacle trajectory and their uncertainty, which combines model-based and data-based prediction methods. Based on the prediction results, a tube-based MPC trajectory planning method is applied to plan a reference trajectory with a small tracking deviation. The tube-based MPC is composed of two parts. One is the MPC with tightened constraints that is used to plan a feasible trajectory according to a nominal vehicle system and driving environment. The other is a state feedback control that is proposed to adjust the above planned trajectory to reduce the tracking deviations. To our knowledge, this paper proposes Kalman filter fusion and tube-based MPC planning method for the first time to consider the uncertainties of trajectory prediction and tracking control meanwhile in the planning. The planning method is verified by simulations and experiments in multiple scenes. Results show that the method is suitable for both static and dynamic scenes. Compared with applying the basic prediction method, the lateral deviation of the proposed method from the ideal trajectory is decreased by 46.5%. Compared with the nominal MPC method, the lateral tracking deviations of the proposed method are decreased by 77.42%.

Due to inevitable parameter uncertainties and disturbances, four-wheel independent drive automated vehicles (4WIDAVs) will produce tracking deviation during the path following process, which have a negative impact on driving safety. Meanwhile, the over-actuated feature of 4WIDAVs will also increase the deviation if not properly handled. To solve this problem, a specific adaptive model predictive control strategy for path following of 4WIDAVs is proposed. Firstly, to obtain a real-time and accurate vehicle dynamics model, the recursive least square method is used to estimate the time-varying uncertainty of tire cornering stiffness. Secondly, based on the real-time updating system model, the modified tube-based model predictive control method is applied to realize path following under the influence of the disturbance. Meanwhile, the compensating yaw moment for controlling vehicle is generated by the designed torque distribution algorithm, which makes full use of the over-actuated feature of 4WIDAVs. Finally, different maneuvers are performed both in simulation and experiment. Results show that the proposed strategy can achieve more accurate path following than the traditional model predictive control and linear quadratic regulator. Compared with the existing controller, the path following accuracy is improved by 41.6% and 60% in simulation and experiment, respectively. Therefore, the proposed strategy is proved to be effective, which provides a theoretical reference for vehicle control in reality.