Robust Physics-Based Manipulation by Interleaving Open and Closed-Loop Execution

Abstract

We present a planning and control framework for physics-based manipulation under uncertainty. The key idea is to interleave robust open-loop execution with closed-loop control. We derive robustness metrics through contraction theory. We use these metrics to plan trajectories that are robust to both state uncertainty and model inaccuracies. However, fully robust trajectories are extremely difficult to find or may not exist for many multi-contact manipulation problems. We separate a trajectory into robust and non-robust segments through a minimum cost path search on a robustness graph. Robust segments are executed open-loop and non-robust segments are executed with modelpredictive control. We conduct experiments on a real robotic system for reaching in clutter. Our results suggest that the open and closed-loop approach results in up to 35% more real-world success compared to open-loop baselines and a 40% reduction in execution time compared to model-predictive control. We show for the first time that partially open-loop manipulation plans generated with our approach reach similar success rates to model-predictive control, while achieving a more fluent/realtime execution. A video showing real-robot executions can be found at https://youtu.be/rPOPCwHfV4g.

Object Reconfiguration with Simulation-Derived Feasible Actions

“…[33] improved the longhorizon planning efficiency of a Monte-Carlo Tree Searchbased planner by integrating parallel simulation. [34,35] use simulators with different precisions and interleaved simulation and execution to improve manipulation planning performance and robustness. These approaches complement SAST.…”