Research On The Key Technology For Auto-parking System

For its enormous market demand, Autonomous-parking technology is a hot research topic in recent Intelligent Vehicle research area. Under the support of the project'Hongqi HQ3 Autonomous Parking Technology'in collaboration with Faw Group Corporation and the emphasis project from National Natural Science Foundation of China:'Research on the key scientific problems in intelligence driving of highway vehicles'(90820302), the key research issues in this thesis are trajectory planning and trajectory tracking&control in the Autonomous Parking system. The specific research issues are: the architecture of the control system, generation of the parking trajectory, high-precision control and etc. Adopting the methodology of combining theoretical analysis and engineering practice, this thesis has achieved the goal of developing a high-precision autonomous parking control system.The main results and innovations of this thesis are as follows:1 Having proposed and implemented the usage of Fractional-Order Calculus in the Autonomous Parking control system, which has solved the high-precision control problem when the Autonomous Vehicle is in low speed.2 In order to overcome the problem in applying'Long Memory Method'or'Short Memory Method'to solve the Fractional-Order Calculus equation, the method based on Gauss Kernel to solve the Fractional-Order Calculus equation for control system is proposed. It is shown that this method has the advantage of fast calculation speed and high accuracy.3 In optimizing the parameters of the Fractional-Order Controller, a self-tuning PIλDμcontroller based on approximate policy iteration is proposed. In this algorithm, the basis function is automatically selected in accordance with the Bellman residual error, leading to an improvement of the Value Function Approximator both in approximation precision and generalization ability.4 The three-layered hierarchical intelligent control framework based on human-machine cooperation is proposed. This framework introduced human wisdom into each layer of the control system. It comprehensively utilizes human's characteristics in qualitative perception, decision-making, planning and machine's superiority in quantitative sensing, computing, high-precision operating. Making use of each side's advantages, the safety and environment adaptability of the autonomous parking system is improved.5 In dealing with various working conditions of lateral parking, we have proposed the method to generate collision-free space in parallel parking. This method can easily calculate the collision-free parking area. Based on the differential flat theory and spline theory, the generation method of autonomous parallel parking trajectory with kinodynamic constraints is proposed, which can generate a viable trajectory for autonomous-parking in the collision-free space. In-vehicle experiments demonstrate that this method could not only avoid obstacles effectively, but also solve the problem of stopping to turning the steering wheel in the parking process, satisfying the demand of continuity.Through large amount of parallel parking experiments, the goal of autonomous parallel parking has been achieved, and the feasibility and effectiveness of the above-mentioned algorithms have been verified. The research results in this thesis have made a great contribution to the accomplishment of the project"Hongqi HQ3 Autonomous Parking Technology".