AN AUTONOMOUS FOREST ROBOT THAT USES A HIERARCHICAL, FUZZY LOGIC CONTROLLER

This article presents a hierarchical fuzzy logic controller that arbitrates recommendations from lower-level modules in order to autonomously guide a robot down forest trails. This robot would be used to move logs or trees from where they are cut to a location where they could be further processed or loaded onto trucks. The lower-level modules contribute recommendations derived from lower-level tasks or behaviors. Each lower-level module provides its own recommendation based on its limited perception of the environment. A fuzzy quality measure is used by the hierarchical controller to determine how best to fuse the individual control recommendations of lower-level modules. The quality measure provides an approximate determination of the value of each lower-level module recommendation. These quality measures, as well as other fuzzy sets used in the controller, were defined with a set of parameters. A computer simulation was used to tune subsets of the fuzzy set parameters to improve the performance of the controller. After these parameters were tuned, they were used in the fuzzy logic controller, which was tested in a vehicle. The results of these vehicle tests are also discussed in the article.