The Research On Multivariable Robust Control Of Active Front Steering And Active Braking

With the increasing importance of vehicle safety issues, the active safety system is becoming more and more diversified and complicated. Various kinds of subsystems are put in the chassis to achieve some specific functions. However, these subsystems are overlapped and coupled in motion, mechanics relation or mechanism relation.They affect each other when they are working and it will seriously reduce their own performance and the stability of vehicle. Therefore, the importance of integrated control system of vehicle chassis comes out. Integrated chassis control can effectively relieve the coupling and reduce the mutual interference among the subsystems. By using the integrated control system, each subsystem can work better than working alone and the stability of vehicles can be improved as also.In this paper, we do a research on the active braking system and active steering system of a light vehicle and design a multivariable coordinated integrated controller of them. We study on the application of robust control strategy on the integrated control of active steering and active braking system.The main contents of this paper include:(1) Certify the structure of multivariable robust controller of the active steering with active braking system. Based on H-infinity robust control theory, we provide the process to design a H-infinity robust controller and theoretical derivation of using the linear matrix inequality(LMI) method to solve the H-infinity robust control problems.(2) Based on the simplified vehicle model, we establish linear two degree of freedom model, the tire model and the active steering model as well as a vehicle auxiliary calculation module. According to the vehicle state equation,complete the design of a multivariable integrated robust controller for the active steering and active braking system of a light vehicle. Work out the ideal sideslip angle and yaw rate according to the control requirements of the vehicle. Create an off-line simulation test platform by the software Carsim and Matlab/Simulink.(3) Choose four typical conditions: single lane condition, sine delay condition, fishhook condition and triangle delay condition. Check out the function of multivariable robust controller of active steering and active braking system of a light vehicle under these conditions by using the off-line simulation platform.Analyse the performance of the controller according to the simulation results of sideslip angle and yaw rate.