Abstract: Through longitudinal braking merely on highway,vehicles are difficult to avoid ahead obstacles.And the typical control method could not satisfy lane-change problem constrained multi-objective optimization.Therefore,the ideal lane-change trajectory model and safety distance model have determined.Based on the theory of Model Predictive Control(MPC) and with the 3-DOF vehicle model,the emergent lane-change control system has designed.To solve the problem,the optimal control problem was converted into a secondary plan problem.The wheel steering angle input was the control variable,and the optimal trajectory of following the ideal lane-change trajectory was the control object.Results of simulations show that the system designed can accurately control vehicle running under the predetermined better trajectory and with the better stability so as to improve the driving safety of vehicles.

Key words: emergent lane change, lane-change trajectory, safety distance model, Model Predictive Control (MPC)