The current research of autonomous vehicle motion control mainly focuses on trajectory tracking and velocity tracking. However, numerous studies deal with trajectory tracking and velocity tracking separately, and the ...The current research of autonomous vehicle motion control mainly focuses on trajectory tracking and velocity tracking. However, numerous studies deal with trajectory tracking and velocity tracking separately, and the yaw stability is seldom considered during trajectory tracking. In this research, a combination of the longitudinal–lateral control method with the yaw stability in the trajectory tracking for autonomous vehicles is studied. Based on the vehicle dynamics, considering the longitudinal and lateral motion of the vehicle, the velocity tracking and trajectory tracking problems can be attributed to the longitudinal and lateral control. A sliding mode variable structure control method is used in the longitudinal control. The total driving force is obtained from the velocity error in order to carry out velocity tracking. A linear time-varying model predictive control method is used in the lateral control to predict the required front wheel angle for trajectory tracking. Furthermore, a combined control framework is established to control the longitudinal and lateral motions and improve the reliability of the longitudinal and lateral direction control. On this basis, the driving force of a tire is allocated reasonably by using the direct yaw moment control, which ensures good yaw stability of the vehicle when tracking the trajectory. Simulation results indicate that the proposed control strategy is good in tracking the reference velocity and trajectory and improves the performance of the stability of the vehicle.展开更多
从玉米各层根中的一条吸入染料溶液后追索其输往地上各器官的踪迹。从 n 层节根可输往叶片范围为≥n 节可见叶。主胚根输往各叶全部纵向大脉,次生胚根每条只输往各叶的50%纵向大脉,各层节根从不同方向输入后,各自通向相应叶片的特定部...从玉米各层根中的一条吸入染料溶液后追索其输往地上各器官的踪迹。从 n 层节根可输往叶片范围为≥n 节可见叶。主胚根输往各叶全部纵向大脉,次生胚根每条只输往各叶的50%纵向大脉,各层节根从不同方向输入后,各自通向相应叶片的特定部位。在茎内,每一条节根吸水后,一般在输入方向的一个局部内上升,输入节位愈高,上升途径愈靠茎的边缘。在籽粒灌浆期,6—7层节根吸入的染料,可在雄穗和雌穗中,包括苞叶、果穗柄、穗轴和籽粒中观察到。从不同方向的根输入时,在繁殖器官中分布方式也不同。展开更多
基金Supported by National Natural Science Foundation of China(Grant Nos.51575103,11672127,U1664258)Fundamental Research Funds for the Central Universities of China(Grant No.NT2018002)+1 种基金China Postdoctoral Science Foundation(Grant Nos.2017T100365,2016M601799)the Fundation of Graduate Innovation Center in NUAA(Grant No.k j20180207)
文摘The current research of autonomous vehicle motion control mainly focuses on trajectory tracking and velocity tracking. However, numerous studies deal with trajectory tracking and velocity tracking separately, and the yaw stability is seldom considered during trajectory tracking. In this research, a combination of the longitudinal–lateral control method with the yaw stability in the trajectory tracking for autonomous vehicles is studied. Based on the vehicle dynamics, considering the longitudinal and lateral motion of the vehicle, the velocity tracking and trajectory tracking problems can be attributed to the longitudinal and lateral control. A sliding mode variable structure control method is used in the longitudinal control. The total driving force is obtained from the velocity error in order to carry out velocity tracking. A linear time-varying model predictive control method is used in the lateral control to predict the required front wheel angle for trajectory tracking. Furthermore, a combined control framework is established to control the longitudinal and lateral motions and improve the reliability of the longitudinal and lateral direction control. On this basis, the driving force of a tire is allocated reasonably by using the direct yaw moment control, which ensures good yaw stability of the vehicle when tracking the trajectory. Simulation results indicate that the proposed control strategy is good in tracking the reference velocity and trajectory and improves the performance of the stability of the vehicle.
文摘从玉米各层根中的一条吸入染料溶液后追索其输往地上各器官的踪迹。从 n 层节根可输往叶片范围为≥n 节可见叶。主胚根输往各叶全部纵向大脉,次生胚根每条只输往各叶的50%纵向大脉,各层节根从不同方向输入后,各自通向相应叶片的特定部位。在茎内,每一条节根吸水后,一般在输入方向的一个局部内上升,输入节位愈高,上升途径愈靠茎的边缘。在籽粒灌浆期,6—7层节根吸入的染料,可在雄穗和雌穗中,包括苞叶、果穗柄、穗轴和籽粒中观察到。从不同方向的根输入时,在繁殖器官中分布方式也不同。
