Comparing harmonic functions and potential fields in the trajectory control of mobile robots

Potential field is a reactive method that has been used for trajectory control of mobile robots. In this method the robot behaves like a particle moving under the influence of an artificial potential produced by the target and the obstacles. This method has lower computational cost than others that utilize maps as a world model. However, one problem or this method is that it can generate regions of local minima. In these regions the driving force vanishes due to specific obstacle and goal configurations and the robot gets trapped. The use of harmonic functions for the potential calculation can solve this problem. In the harmonic function method the environment is represented by a grid, in which cells with an obstacle have their potential value set to 1 whereas cells that contain the target have their potential value set to 0. A relaxation algorithm is then employed to calculate the harmonic potential among the obstacles and the target. These two techniques have been applied in robot soccer environment to develop game strategies. Results obtained show that both techniques present better results when compared to the standard strategy or the FIRA Simulator. Further, a comparison of these techniques is presented for showing the advantages and disadvantages existing in each one of them.