| With the rapid development of artificial intelligence technology and Internet technology,highly intelligent driverless cars will be an inevitable trend in the development of the automotive industry.Unmanned vehicles can not only effectively improve the efficiency of traffic operation and ensure the safety of vehicles,but also can replace humans in completing certain special tasks.The steering control of unmanned vehicles is one of the important research contents in the entire field of unmanned driving technology,and it is also a key factor for unmanned vehicles to achieve stable and accurate driving.The quality of unmanned vehicle steering control will directly affect the path tracking effect.This thesis refits and designs the unmanned steering control device on the actual vehicle platform,and uses the model predictive control algorithm to study the unmanned steering control.First of all,the steering control architecture of the driverless car is introduced,and the angle transmission ratio of the steering system of the actual vehicle is calibrated.The steering actuator is modified according to the design of the actual vehicle platform,and its working principle is explained.The analysis of the steering in the steering actuator is briefly explained.Performance parameters of hardware such as motors and rotation angle sensors.Secondly,establish the vehicle dynamics model and kinematics model to describe the operating state of the vehicle,and provide the model basis and basis for the specific design of the steering control algorithm;in order to improve the stability of the steering control,the "magic formula" tire model is quoted,and the formula is used to The tire mechanics characteristics are analyzed;based on the established vehicle system model,the model predictive control algorithm is combined with the characteristics of the researched control target,and the appropriate state quantity,control quantity and output quantity are selected to complete the establishment of the predictive model and the discretization of the continuous system.The objective function is designed,the relevant constraints are analyzed and determined,and the derivation process of the algorithm is completed.Then,the model predictive steering controller is co-simulated and analyzed,Simulink and Car Sim co-simulation platform is built,and the dual-line-shifting trajectory is selected for the steering stability simulation analysis;the model predictive control system is compared and analyzed under different operating conditions and different control parameters for steering The influence of control,to verify the stability and accuracy of the steering control of the driverless car.The actual vehicle verified the feasibility of the steering control system proposed in this topic.The modified Zhonghua V3 was used as a test platform to introduce the necessary test environment of the actual vehicle;the upper control module and the lower control module of the steering control system were analyzed.The debugging realization of the steering control algorithm is explained,and the actual vehicle test is completed based on the positioning system and offline map.Analyzing the results of the driving state of the test vehicle,it verifies the effectiveness of the designed controller in the actual vehicle environment. |
