A hybrid planning approach to robot construction problems

Official URL: http://risc01.sabanciuniv.edu/record=b2066372 (Table of Contents)

We study robot construction problems where multiple autonomous robots rearrange prefabricated components to build stable structures. Robot construction problems can play a vital role in construction industries where the tasks such as designing a desired structure, planning for the necessary actions, and constructing structures from available components can be performed by the robots. Robotic construction may especially be useful in places, such as disaster zones or the space, where it is not safe or feasible for humans to visit. In these unsafe or hard-to-reach places, robots can build necessary buildings, bridges or shelters using the surrounding materials. We view robot construction problems as planning problems: find a plan (i.e., a sequence of actions) to obtain a final stable configuration of prefabricated objects satisfying some goal conditions, from a given initial configuration. These problems are challenging from the perspective of task planning ii since they may need incorporation of preexisting structure into the final design, pre-assembly of movable substructures, and use of extra blocks as temporary supports or counterweights during construction. These problems are challenging from the perspective of geometric reasoning as well, since they need feasibility checks to ensure reachability of a block, to avoid collisions of blocks, and to ensure stability of complex structures. We propose a formal hybrid planning framework to address these challenges using Answer Set Programming, and state-of-the-art feasibility checkers. This framework not only decides for a stable final configuration of the structure, but also computes the order of manipulation tasks for multiple autonomous robots to build the structure from an initial configuration, while simultaneously ensuring the stability, supportedness and other desired properties of the partial construction at each step of the plan. We show the usefulness of our approach on a wide variety of robot construction tasks, including bridge building and overhang construction scenarios, and using different types of objects, including cylindrical ones. We demonstrate the applicability of our approach through dynamic simulations and physical implementations with a bi-manual Baxter robot.