Robust Object Manipulation for Fully-Actuated Robotic Hands

Abstract

Object manipulation is the ability to rotate/translate an object held within a grasp. Humans have exploited this ability to effectively use tools and interact with the environment. Over the past decades, robotics research has worked to translate object manipulation capabilities to robotic hands. Applications of object manipulation for robotic hands include autonomous manipulation, teleoperation in extreme environments, and prosthetics. Despite advancements made, robotic hand research has not yet progressed to handle uncertainties found in the real world. Many existing grasp methods to control robotic hands require a priori information and high fidelity sensors typically restricted to laboratory settings. The objective of this thesis is to develop robust means of object manipulation for robotic hands.

This thesis focuses on the concept of tactile-based blind grasping to address robustness concerns in real-world applications. In tactile-based blind grasping, the robotic hand only has access to proprioceptive (joint angle) and tactile measurements. No a priori information about the object is known. This reflects real-world applications, such as prosthetics, where disturbances in the form of uncertain object models are part of everyday use.

In this dissertation, novel object manipulation control methods are developed for robotic hands in tactile-based blind grasping. The first method ensures stability of the hand-object system to a desired object pose despite uncertain object weight, shape, center of mass, and contact locations. The second method is an extension of the first, but also ensures the contact points do not slip during the manipulation motion. The final control addresses all grasp conditions that must be satisfied, including slip, to ensure the grasp does not fail during manipulation. This final control is applicable not only to the control methods presented here, but to most manipulation controllers developed in the literature. The proposed controllers are presented with associated stability guarantees and validated in simulation and hardware.