Planning robot motion strategies under geometric uncertainty constraints

This paper presents an approach to plan robust motion strategies of a robot navigating through an environment composed of polygonal obstacles subject to geometric uncertainty constraints. The contacts of the robot against the obstacles are used to reduce its position and orientation uncertainties and to guide the robot to its goal configuration. We describe a motion planner based on this approach which generates both, free space motions and compliant motions (contact based motions). An explicit geometric model for the uncertainty is used to estimate the reachability of the goal and the intermediate subgoals (these are generated when the final goal is not reachable from the current robot configuration). Two functions are combined to explore the valid space : (1) a contact-based potential field function is used to generate continuous motions pulling the robot towards target attractors; (2) an exploration function is used to determine possible subgoals allowing to progress towards the ultimate goal when local minima of the previous function occur.