Stair Climbing for Vehicles with Articulated Tracked Arms: Closed-Loop Flippers Control

Abstract

We present a new approach to the stair-climbing problem for robots that rely on actively articulated tracked arms. The robot in question is considered to have a main locomotion system, such as wheels or tracks, and arms that can be controlled to extend the robot's mobility when needed. Further, we also assume the robot is equipped with a depth sensor (for stair perception) and an IMU (solely for orientation estimates). This paper's proposed key feature is to analyze the robot's differential kinematics as a planar manipulator with a position constraint. For the proposed model, we then present a state feedback control law with stability and convergence properties to move arms, guiding the robot towards the stairs autonomously. The controller fits the tracks to the floor, making the robot perform appropriate maneuvers, like a snake climbing an inclined plane, preventing sudden movements, improving traction, and avoiding collisions with the floor. The presented method seems to be a novel way to interpret the problem. The proposed control scheme is validated in a real robot, and experimental results are presented.