Research On Adaptive Fault-tolerant Control Method For Distributed Electric Vehicles

Energy utilization and sustainable development are the development goals of the current world.The oil consumption of traditional automobiles has brought tremendous pressure on national energy.Now new energy vehicles have become the current trend of world development.Distributed electric vehicles have gradually entered the public’s vision.When a distributed electric vehicle fails while driving,a catastrophic traffic accident may be caused,and the life safety of the driver cannot be guaranteed.Therefore,the importance of fault tolerance research on the vehicle is self-evident.Based on the characteristics of distributed electric vehicles with drive redundancy,this thesis studies the yaw stability of the vehicle after the wheel motor fails completely.First,the failure modes of the vehicle drive system are classified into 6 types of 15 failure situations,and the control objectives of the vehicle are divided under different failure modes.Then,the model frame of the vehicle is simplified,and the modular idea is adopted to establish the vehicle kinematics model,the tire model,the vehicle rotation dynamics model,and the wheel motor motor model that move around the X and Y axes and rotate around the Z axis.Through the sub-module link,a seven-degree-of-freedom model of the vehicle is finally built.Through the joint simulation of the existing vehicle model in the Carsim software,it is verified that the built vehicle model can replace the real vehicle model.Secondly,a tiered control structure is used to control the yaw stability of the vehicle after the failure.The upper controller is designed as model predictive control and adaptive PID control.It follows or predicts the expected longitudinal speed of the vehicle and calculates the total longitudinal force of the vehicle.The design of the lower controller is based on the total adhesion rate of the tire as the objective function and the corresponding boundary conditions.For different fault conditions,a nominal control and reconstruction control allocation scheme is designed.When the vehicle is free of faults,nominal control allocation is used;when the vehicle is broken,refactoring control allocation is used.Finally,the seven-degree-of-freedom model built and the designed fault-tolerant control strategy are jointly simulated,and offline simulation experiments of four operating conditions are carried out.Through comparative experiments,the effectiveness of the adaptive fault-tolerant control algorithm is verified,which can improve the horizontal cross-section of the vehicle.Pendulum stability.In order to verify the effectiveness and reliability of the fault-tolerant control strategy on a real vehicle,a hardware-in-the-loop simulation system based on the NI platform was built.The reliability of the hardware-in-the-loop system and the real-timeness and effectiveness of the designed fault-tolerant control algorithm are verified by the angular step condition of a single round of failure.