Abstract

We propose a method that simultaneously estimates and controls extrinsic contact with tactile feedback. The method enables challenging manipulation tasks that require finesse at the contact, such as stably placing an unknown object on a surface or even on a thin rod standing upright. A factor graph-based estimator-controller framework fuses a sequence of tactile measurements to estimate the contact state, such as the location of extrinsic contact between the grasped object and the environment and the intrinsic wrench exerted from the tactile sensor to the object. The same architecture also plans the robot motion to allow the collection of measurements from different poses while satisfying control objectives such as minimizing the amount of intrinsic wrench or minimizing tangential force at the extrinsic contact. The proposed method shows a contact localization error of less than 1 mm. It also reduces the tangential force at the extrinsic contact, which allows localizing the contact without slipping, even in a slippery environment. The proposed method also works for multiple contact formations (point, line, patch contact) and detects transitions between them.

Contact: Sangwoon Kim (sangwoon@mit.edu)