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Automotive Engineering ›› 2023, Vol. 45 ›› Issue (12): 2299-2309.doi: 10.19562/j.chinasae.qcgc.2023.12.012

Special Issue: 智能网联汽车技术专题-规划&决策2023年

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Parallel Parking Trajectory Planning Based on Double-Layer Solution Strategy

Hongchang Zhang1,2,3,Peng Ning1,2,3,Jie Yang1,2,3,Jianwei Song1,2,3,Lin Hao1,2,3,Juan Zeng1,2,3()   

  1. 1.Wuhan University of Technology,Hubei Key Laboratory of Modern Auto Parts Technology,Wuhan 430070
    2.Wuhan University of Technology,Auto Parts Technology Hubei Collaborative Innovation Center,Wuhan 430070
    3.Wuhan University of Technology,Hubei Technology Research Center of New Energy and Intelligent Connected Vehicle Engineering,Wuhan 430070
  • Received:2023-04-05 Revised:2023-05-11 Online:2023-12-25 Published:2023-12-21
  • Contact: Juan Zeng E-mail:zhc112@126.com

Abstract:

Trajectory planning plays a key role in shortening parking time and reducing tracking difficulty, as it connects the upper-level perception and the lower-level control in parking systems. However, it is challenging to balance trajectory quality, generalization ability, and computational efficiency in parallel parking trajectory planning. To address this issue, the parallel parking trajectory planning based on double-layer solution strategy (DLSS) is proposed. The strategy includes two layers: in the first layer, the parallel parking path is divided into two segments connected by anchor points. The anchor point is identified through a backward path planning approach. The paths from the endpoint to the anchor point and from the anchor point to the starting point are planned separately. Then, a "time-optimal" profile is added to the path, and the state and control variables at specific time points are obtained in reverse order. In the second layer, the simultaneous orthogonal configuration method is used to transform the continuous state and control variables in the parallel parking optimal control into discrete variables in the trajectory nonlinear programming. The state and control variables obtained in the first layer are used as the initial values for the nonlinear programming to obtain numerical solutions. Five parallel parking scene models are established and simulated, and the results show that the optimal trajectory that meets the constraints requirements can be planned for different parking starting postures and parking space sizes, which improves the generation quality and generalization ability of trajectories, and has satisfactory computational efficiency.

Key words: trajectory planning, double-layer solution strategy, parallel parking, numerical optimization