Path-planning algorithms for self-driving vehicles basedon improved RRT-Connect

This study aims to solve path planning of ntelligent vehicles in self driving In this study,an improved path planning method com-bining constraints of the environment and vehicle is proposed.The algorithm designs a reasonable path cost function,then uses a heuristic guided search strategy to improve the speed and quality of path planning,and finally generates smooth and continuous cur-vature paths based on the path post-processing method focusing on the requirements of path smoothness.A simulation test shows that compared with the basic rapidly-exploring random tree(RRT),RRT-Connect and RRT*algorithms,the path length of the proposed algorithm can be reduced by 19.7%,29.3%and 1%respectively,and the maximum planned path curvature of the proposed algorithm is 0.0796 mr1 and 0.1512 mi respectively.under the condition of a small amount of planning time.The algorithm can plan the more suitable driving path for intelligent vehicles in a complex environment.

Wrinkling modes of graphene oxide assembled on curved surfaces

Assembling two-dimensional(2D)sheets into macroscopic three-dimensional(3D)forms has created a promising material family with rich functionalities.Multiscale wrinkles are intrinsic features of 2D sheets in their 3D assembles.Therefore,the precise wrinkling modulation optimizes the transition of outstanding properties of 2D sheets to expected performances of assembled materials and dominates their fabrication process.The wrinkling evolution of 2D sheets assembling onto flat surfaces has been extensively understood,however,the wrinkling behaviors on the more generally curved surface still remain unclear.Here,we investigate the wrinkling behaviors of graphene oxide sheets assembled onto curved surfaces and reveal the selection rule of wrinkling modes that determined by the curvature mismatch between 2D sheets and target surfaces.We uncover that three wrinkling modes including isotropic cracked land,labyrinth,and anisotropic curtain phases,respectively emerge on flat,spherical,and cylindrical surfaces.A favorable description paradigm is offered to quantitatively measure the complex wrinkling patterns and assess the curvature mismatch constraint underlying the wrinkling mode selection.This research provides a general and quantitative description framework of wrinkling modulation of 2D materials such as high performance graphene fibers,and guides the precise fabrication of particles and functional coatings.

A new localization theory of adaptive machining of near-net-shape blades

In the fabrication of aero-engine blades,a great deal is gained when massive material removal is avoided at the end of the process,and as little as possible material is left on the blade billet.Due to the uncertainty of pre-process,the billet shapes are inconsistent.Sometimes,the near-net-shape billet doesn’t cover the blade design surface to be cut.Therefore,blade localization is necessary for these billets before the machining.In conventional localization methods,the design surface’s location focused on guaranteeing enough material to be cut.However,because the to-becut surface is in near-net and free-form shape,it is difficult to find a valid localized surface model to generate the tool path.Different from the localized surface is taken as rigid in previous investigation,it is allowed to deviate from the design surface no more than the tolerance band.In term of this principle,the tolerance band is utilized to promote localization ability.A series of optimization models with different priorities is established to avoid the abandonment expensive blade billet.Finally,with the experiments performed on the near-net-shape blades,the blade localization theory and the promotion of localization ability are verified.