The Layered Coordination Control And Optimization On Vehicle Rollover Stability And Ride Comfort

Most Anti_Roll system cost the vehicle riding comfort to improve the equivalent roll stiffness.Active Roll Bar System(ARS) generate different torques in front and rear vehicle axle,which not only can improve rollover stability,but also the insufficient or excessive turning.Differential Braking Control(DBC) is also known as Direct Yawing Control(DYC),it's a active control method according to apply different braking force in different wheel to change driving operation.When the tire lateral force close to saturation state and lose movement stability,it can well solves this problem and can improves the vehicle riding comfort,too.In this paper, according to vehicle system dynamics theory, we set up a 9-freedom vehicle dynamic system contained lateral, vertical, longitudinal and horizontal pendulum, roll and four-wheel vertical displacement based on vehicle and tire systems coupling in longitudinal, lateral and vertical.The Magic tire model was built in longitudinal slipping,side slipping and longitudinal_side slipping condition.we also analyzed the factors which contributed to rollover stability on classic model,then we established the vehicle rollover stability and riding comfort evaluation system.Secondly,ARS system was fully designed. Roll Angle and its velocity were limited in a safe range through fuzzy PID control. It had demonstrated ARS system's effective control and performance. In the meantime, DBC is devised, to calculate the ideal yaw angle based on linear two degrees vehicle model,we determined braking force and braking tire according to insufficient or excessive turning.Through the analysis of two subsystems, established a layered coordination control system for vehicle, this improved the rollover stability meanwhile ensured the riding comfort.Finally, using rollover stability and riding comfort as targets,we optimized two triggering factors of coordination controller and four quantitative factors of child controllers by genetic algorithm, the simulation results showed the necessity and effectiveness of optimization.