Distributed Trajectory Planning for a Group of UGVs Carrying a Load Considerting Terrain Properties

Abstract

The article studies a trajectory planning task for a group of UGVs with a consideration of wheels-terrain adhesion variation. Within this paper a brief analysis devoted to existing trajectory planning is done. It outcomes with a conclusion of a necessity to produce additional research within this topic. This paper suggests to use a Sampling-based method to solve this trajectory planning task. An algorithm of rapidly exploring random tree (RRT) is used as a basic algorithm. An advantage of this method (typical for Sampling-based methods) is a simplicity of various non-linear restrictions introduction (e.g. obstacles, differential restrictions etc.). In addition we should mention good potential for algorithm parallelization, because of tree structure of the algorithm. However there exists a shortage of the proposed methods — a high consumption of computational resources, and as an outcome a long calculus duration. This paper proposes to overcome this shortage via distributing of computation among UGVs — actors of a group. This is followed by a comparative analysis of distributed and centralized methods. Analysis shows that the main advantage of proposed method is that it can use almost all models of interaction between wheel and terrain. The latter can act a component for calculation of restrictions for motion acceleration over certain types of terrain. Within this paper we did not study models of interaction between wheel and terrain, but instead used empirical data of allowed values of tangential and normal accelerations for specific UGVs in particular conditions. In final part we present results of simulation witch confirm effectiveness of proposed methods.