Learning for Tactile Manipulation

Tactile sensing affords robots the opportunity to dexterously manipulate objects in-hand without the need of strong object models and planning. Our demonstration focuses on learning for tactile, in-hand manipulation by robots. We address learning problems related to the control of objects in-hand, as well as perception problems encountered by a robot exploring its environment with a tactile sensor. We demonstrate applications for three specific learning prob- lems: learning to detect slip for grasp stability, learning to reposition objects in-hand, and learning to identify objects and object properties through tactile exploration. We address the problem of learning to detect slip of grasped objects. We show that the robot can learn a detector for slip events which generalizes to novel objects. We leverage this slip detector to produce a feedback controller that can stabilize objects during grasping and manipulation. Our work compares a number of supervised learning approaches and feature representations in order to achieve reliable slip detection. Tactile sensors provide observations of high enough dimension to cause prob- lems for traditional reinforcement learning methods. As such, we introduce a novel reinforcement learning (RL) algorithm which learns transition functions embedded in a reproducing kernel Hilbert space (RKHS). The resulting policy search algorithm provides robust policy updates which can efficiently deal with high-dimensional sensory input. We demonstrate the method on the problem of repositioning a grasped object in the hand. Finally, we present a method for learning to classify objects through tactile exploration. The robot collects data from a number of objects through various exploratory motions. The robot learns a classifier for each object to be used dur- ing exploration of its environment to detect objects in cluttered environments. Here again we compare a number of learning methods and features present in the literature and synthesize a method to best work in human environments the robot is likely to encounter. Users will be able to interact with a robot hand by giving it objects to grasp and attempting to remove these objects from the robot. The hand will also perform some basic in-hand manipulation tasks such as rolling the object between the fingers and rotating the object about a fixed grasp point. Users will also be able to interact with a touch sensor capable of classifying objects as well as semantic events such as slipping from a stable contact location.