Overcoming obstacles with variable geometry and inclination by rolling mobile robots using their arm

摘要

Abstract Outdoor mobile robots must navigate uneven terrains with obstacles that sometimes cannot be avoided; therefore, strategies have been developed for robots to overcome them. In most cases, these strategies have been modeled considering movement over horizontal surfaces and with the robot positioned directly in front of the obstacle, but this idealization does not occur in most real cases. Therefore, this article describes a strategy for obstacle overcoming, useful when the robot faces obstacles on inclined terrains and at an oblique angle relative to the robot’s trajectory, considering rollover stability during the process, based on the reaction force criterion. This strategy can be used by mobile robots with wheels and an articulated arm whose end effector can contact the ground, and it consists of a sequence of standard movements that include the use of the arm, whose variable location was defined through a system developed using fuzzy logic. The designed strategy was validated through simulations and then implemented on the Lázaro robot, verifying its effectiveness through experimental tests. With it, the robot can overcome obstacles such as steps, ramps, and ditches from any position; additionally, it increased the ability to overcome obstacles with a height close to twice the radius of the robot’s wheels.