Study On Path Planning And Path Tracking Method For Fully-Automatic Parallel Parking

Due to the increasing car ownership and the expansion of urban construction land,the parking space is becoming smaller and smaller which caused parking problems.fully-automatic parking which is the key part of driverless has become a hot research spot of the driverless domain,since it could ensure parking smoothness and security,greatly reduced parking accident probability and effectively solve parking problems.To research the path planning and the path tracking control which are two key core problems of the Fully-automatic parking system to improve parking smoothness and security could have great scientific significance and application value.This essay is mainly fully-automatic parallel parking system double-path planning and path tracking control.Combing with theoretical analysis,numerical optimization,predictive control and other theories,the static path planning,dynamic path planning and path tracking are completed and Fully-automatic Parking is fully accomplished.All the theories are verified through simulation.Specific as follows:(1)Fully-automatic parallel parking static path planning.Based on Arman steering principle and two pieces of arc path planning method,vehicle dynamic model is established,parking key characteristic parameters such as initial position and minimum size of parking are solved.Through the analysis of obstacle constraints and vehicle mechanical constraints,the nonlinear constrained optimization function is established aiming at minimum path curvature.Based on fmincon function optimization strategy,the key characteristic parameters of the B-spline path trajectories are determined.Simulation models are constructed and the rationality of the parallel static parking dynamic path planning is verified.(2)Fully-automatic parallel Parking dynamic path planning.Aiming at environment,road conditions,the parallel parking dynamic path planning model established in order to improve the success rate of automatic parking system.Three types of dynamic path planning interfere border for three kinds of high frequency collisions parking are designed respectively are determined.According to different parking collision warning information,the constraint and nonlinear constraints optimization function are rebuilt.Based on fmincon function optimization strategy,the real-time dynamic path is established based on B-spline Simulation models are constructed and the rationality of the parallel parking dynamic path planning is verified.(3)Fully-automatic parallel parking path tracking control.In the light of uncertain factors interference in the process of automatic parking path tracking problem,Generalized Predictive Control path tracking controller is constructed in order to improve the path tracking robustness.Based on Least-squares like techniques with forgetting factors,the CARIMA model parameters are estimated and the problems of complex dynamics modeling are avoided.Path tracking controllers such as steering controller,braking controller and acceleration controller are designed,lateral control system for the path tracking based on steering wheel angle and Longitudinal velocity tracking control based on accelerator pedal control and braking pedal control are realized.(4)The simulation verification of fully-automatic parallel parking control system.The path tracking controller is designed based on simulink.The real vehicle simulation model is constructed based on CarSim.The fully-automatic parallel parking control cosimulation platform is established based on Simulink/Car Sim,meanwhile the rationality of the path planning and the exactness of the path tracking control strategy are verified.The effects of the GPC path tracking controller under conditions of double lane change is analyzed,and the tracking exactness and control robustness of the path tracking controller based on improved GPC under the condition of high speed are verified.