Learning Bimanual Scooping Policies for Food Acquisition
Proceedings of The 6th Conference on Robot Learning, PMLR 205:1510-1519, 2023.
A robotic feeding system must be able to acquire a variety of foods. Prior bite acquisition works consider single-arm spoon scooping or fork skewering, which do not generalize to foods with complex geometries and deformabilities. For example, when acquiring a group of peas, skewering could smoosh the peas while scooping without a barrier could result in chasing the peas on the plate. In order to acquire foods with such diverse properties, we propose stabilizing food items during scooping using a second arm, for example, by pushing peas against the spoon with a flat surface to prevent dispersion. The addition of this second stabilizing arm can lead to a new set of challenges. Critically, these strategies should stabilize the food scene without interfering with the acquisition motion, which is especially difficult for easily breakable high-risk food items, such as tofu. These high-risk foods can break between the pusher and spoon during scooping, which can lead to food waste falling onto the plate or out of the workspace. We propose a general bimanual scooping primitive and an adaptive stabilization strategy that enables successful acquisition of a diverse set of food geometries and physical properties. Our approach, CARBS: Coordinated Acquisition with Reactive Bimanual Scooping, learns to stabilize without impeding task progress by identifying high-risk foods and robustly scooping them using closed-loop visual feedback. We find that CARBS is able to generalize across food shape, size, and deformability and is additionally able to manipulate multiple food items simultaneously. CARBS achieves 87.0% success on scooping rigid foods, which is 25.8% more successful than a single-arm baseline, and reduces food breakage by 16.2% compared to an analytical baseline. Videos can be found on our website at https://sites.google.com/view/bimanualscoop-corl22/home.