87 research outputs found
Visuo-Haptic Grasping of Unknown Objects through Exploration and Learning on Humanoid Robots
Die vorliegende Arbeit befasst sich mit dem Greifen unbekannter Objekte durch humanoide Roboter. Dazu werden visuelle Informationen mit haptischer Exploration kombiniert, um Greifhypothesen zu erzeugen. Basierend auf simulierten Trainingsdaten wird außerdem eine Greifmetrik gelernt, welche die Erfolgswahrscheinlichkeit der Greifhypothesen bewertet und die mit der größten geschätzten Erfolgswahrscheinlichkeit auswählt. Diese wird verwendet, um Objekte mit Hilfe einer reaktiven Kontrollstrategie zu greifen. Die zwei Kernbeiträge der Arbeit sind zum einen die haptische Exploration von unbekannten Objekten und zum anderen das Greifen von unbekannten Objekten mit Hilfe einer neuartigen datengetriebenen Greifmetrik
Simultaneous Tactile Exploration and Grasp Refinement for Unknown Objects
This paper addresses the problem of simultaneously exploring an unknown
object to model its shape, using tactile sensors on robotic fingers, while also
improving finger placement to optimise grasp stability. In many situations, a
robot will have only a partial camera view of the near side of an observed
object, for which the far side remains occluded. We show how an initial grasp
attempt, based on an initial guess of the overall object shape, yields tactile
glances of the far side of the object which enable the shape estimate and
consequently the successive grasps to be improved. We propose a grasp
exploration approach using a probabilistic representation of shape, based on
Gaussian Process Implicit Surfaces. This representation enables initial partial
vision data to be augmented with additional data from successive tactile
glances. This is combined with a probabilistic estimate of grasp quality to
refine grasp configurations. When choosing the next set of finger placements, a
bi-objective optimisation method is used to mutually maximise grasp quality and
improve shape representation during successive grasp attempts. Experimental
results show that the proposed approach yields stable grasp configurations more
efficiently than a baseline method, while also yielding improved shape estimate
of the grasped object.Comment: IEEE Robotics and Automation Letters. Preprint Version. Accepted
February, 202
3D Shape Perception from Monocular Vision, Touch, and Shape Priors
Perceiving accurate 3D object shape is important for robots to interact with
the physical world. Current research along this direction has been primarily
relying on visual observations. Vision, however useful, has inherent
limitations due to occlusions and the 2D-3D ambiguities, especially for
perception with a monocular camera. In contrast, touch gets precise local shape
information, though its efficiency for reconstructing the entire shape could be
low. In this paper, we propose a novel paradigm that efficiently perceives
accurate 3D object shape by incorporating visual and tactile observations, as
well as prior knowledge of common object shapes learned from large-scale shape
repositories. We use vision first, applying neural networks with learned shape
priors to predict an object's 3D shape from a single-view color image. We then
use tactile sensing to refine the shape; the robot actively touches the object
regions where the visual prediction has high uncertainty. Our method
efficiently builds the 3D shape of common objects from a color image and a
small number of tactile explorations (around 10). Our setup is easy to apply
and has potentials to help robots better perform grasping or manipulation tasks
on real-world objects.Comment: IROS 2018. The first two authors contributed equally to this wor
In-Hand Manipulation of Unknown Objects with Tactile Sensing for Insertion
In this paper, we present a method to manipulate unknown objects in-hand
using tactile sensing without relying on a known object model. In many cases,
vision-only approaches may not be feasible; for example, due to occlusion in
cluttered spaces. We address this limitation by introducing a method to
reorient unknown objects using tactile sensing. It incrementally builds a
probabilistic estimate of the object shape and pose during task-driven
manipulation. Our approach uses Bayesian optimization to balance exploration of
the global object shape with efficient task completion. To demonstrate the
effectiveness of our method, we apply it to a simulated Tactile-Enabled Roller
Grasper, a gripper that rolls objects in hand while collecting tactile data. We
evaluate our method on an insertion task with randomly generated objects and
find that it reliably reorients objects while significantly reducing the
exploration time
Touch if it's Transparent! ACTOR: Active Tactile-Based Category-Level Transparent Object Reconstruction
Accurate shape reconstruction of transparent ob-jects is a challenging task due to their non-Lambertian surfaces and yet necessary for robots for accurate pose perception and safe manipulation. As vision-based sensing can produce erroneous measurements for transparent objects, the tactile modality is not sensitive to object transparency and can be used for reconstructing the object's shape. We propose AC-TOR, a novel framework for ACtive tactile-based category-level Transparent Object Reconstruction. ACTOR leverages large datasets of synthetic object with our proposed self-supervised learning approach for object shape reconstruction as the collection of real-world tactile data is prohibitively expensive. ACTOR can be used during inference with tactile data from category-level unknown transparent objects for reconstruction. Furthermore, we propose an active-tactile object exploration strategy as probing every part of the object surface can be sample inefficient. We also demonstrate tactile-based category-level object pose estimation task using ACTOR. We perform an extensive evaluation of our proposed methodology with real-world robotic experiments with comprehensive comparison studies with state-of-the-art approaches. Our proposed method outperforms these approaches in terms of tactile-based object reconstruction and object pose estimation
Robotic Haptic Exploration of Shape and Symmetry
This thesis presents research on the use of symmetric models during haptic exploration procedures that have the objective of determining an object’s shape. These haptic exploration techniques, and their subsequent determination of a surface’s geometric properties, are crucial to allow robots to interact with a greater variety of objects, especially as the field of robotics transitions into unstructured environments. Symmetry is an extremely frequent shape property, especially in man-made objects, and it provides shape information that becomes useful in grasping and manipulation tasks, as well as enriching shape information for the aforementioned haptic exploration tasks. In this work, we present an improvement to Gaussian Process-driven exploration tasks. This method allows to describe symmetry to obtain a more precise shape estimation during active exploration, and can even be discovered in real time during the exploration procedure itself. This work involved the creation of a custom software resource to perform Gaussian Process regression with the addition of symmetries, and include a novel method of representing rotational symmetries. These novel models were then used in shape exploration procedures of 2D and 3D surfaces, both in a simulated environment and in an actual robotic task, using a series of custom-made contact sensors. These procedures are able to discover symmetry of each particular object in real time. This property can also be exploited, resulting in shape estimations that have a lower surface error and uncertainty. Additionally, exploration experiments that use these symmetry-finding procedures also require a lower total number of physical contacts and take less time to finish
Tactile Perception And Visuotactile Integration For Robotic Exploration
As the close perceptual sibling of vision, the sense of touch has historically received less than deserved attention in both human psychology and robotics. In robotics, this may be attributed to at least two reasons. First, it suffers from the vicious cycle of immature sensor technology, which causes industry demand to be low, and then there is even less incentive to make existing sensors in research labs easy to manufacture and marketable. Second, the situation stems from a fear of making contact with the environment, avoided in every way so that visually perceived states do not change before a carefully estimated and ballistically executed physical interaction. Fortunately, the latter viewpoint is starting to change. Work in interactive perception and contact-rich manipulation are on the rise. Good reasons are steering the manipulation and locomotion communities’ attention towards deliberate physical interaction with the environment prior to, during, and after a task.
We approach the problem of perception prior to manipulation, using the sense of touch, for the purpose of understanding the surroundings of an autonomous robot. The overwhelming majority of work in perception for manipulation is based on vision. While vision is a fast and global modality, it is insufficient as the sole modality, especially in environments where the ambient light or the objects therein do not lend themselves to vision, such as in darkness, smoky or dusty rooms in search and rescue, underwater, transparent and reflective objects, and retrieving items inside a bag. Even in normal lighting conditions, during a manipulation task, the target object and fingers are usually occluded from view by the gripper. Moreover, vision-based grasp planners, typically trained in simulation, often make errors that cannot be foreseen until contact. As a step towards addressing these problems, we present first a global shape-based feature descriptor for object recognition using non-prehensile tactile probing alone. Then, we investigate in making the tactile modality, local and slow by nature, more efficient for the task by predicting the most cost-effective moves using active exploration. To combine the local and physical advantages of touch and the fast and global advantages of vision, we propose and evaluate a learning-based method for visuotactile integration for grasping
Deep Learning Approaches to Grasp Synthesis: A Review
Grasping is the process of picking up an object by applying forces and torques at a set of contacts. Recent advances in deep learning methods have allowed rapid progress in robotic object grasping. In this systematic review, we surveyed the publications over the last decade, with a particular interest in grasping an object using all six degrees of freedom of the end-effector pose. Our review found four common methodologies for robotic grasping: sampling-based approaches, direct regression, reinforcement learning, and exemplar approaches In addition, we found two “supporting methods” around grasping that use deep learning to support the grasping process, shape approximation, and affordances. We have distilled the publications found in this systematic review (85 papers) into ten key takeaways we consider crucial for future robotic grasping and manipulation research
Sense, Think, Grasp: A study on visual and tactile information processing for autonomous manipulation
Interacting with the environment using hands is one of the distinctive
abilities of humans with respect to other species. This aptitude reflects on
the crucial role played by objects\u2019 manipulation in the world that we have
shaped for us. With a view of bringing robots outside industries for supporting
people during everyday life, the ability of manipulating objects
autonomously and in unstructured environments is therefore one of the basic
skills they need. Autonomous manipulation is characterized by great
complexity especially regarding the processing of sensors information to
perceive the surrounding environment. Humans rely on vision for wideranging
tridimensional information, prioprioception for the awareness of
the relative position of their own body in the space and the sense of touch
for local information when physical interaction with objects happens. The
study of autonomous manipulation in robotics aims at transferring similar
perceptive skills to robots so that, combined with state of the art control
techniques, they could be able to achieve similar performance in manipulating
objects. The great complexity of this task makes autonomous
manipulation one of the open problems in robotics that has been drawing
increasingly the research attention in the latest years.
In this work of Thesis, we propose possible solutions to some key components
of autonomous manipulation, focusing in particular on the perception
problem and testing the developed approaches on the humanoid robotic platform iCub. When available, vision is the first source of information
to be processed for inferring how to interact with objects. The object
modeling and grasping pipeline based on superquadric functions we designed
meets this need, since it reconstructs the object 3D model from partial
point cloud and computes a suitable hand pose for grasping the object.
Retrieving objects information with touch sensors only is a relevant skill
that becomes crucial when vision is occluded, as happens for instance during
physical interaction with the object. We addressed this problem with
the design of a novel tactile localization algorithm, named Memory Unscented
Particle Filter, capable of localizing and recognizing objects relying solely
on 3D contact points collected on the object surface. Another key point of
autonomous manipulation we report on in this Thesis work is bi-manual
coordination. The execution of more advanced manipulation tasks in fact
might require the use and coordination of two arms. Tool usage for instance
often requires a proper in-hand object pose that can be obtained via
dual-arm re-grasping. In pick-and-place tasks sometimes the initial and
target position of the object do not belong to the same arm workspace, then
requiring to use one hand for lifting the object and the other for locating it
in the new position. At this regard, we implemented a pipeline for executing
the handover task, i.e. the sequences of actions for autonomously passing an
object from one robot hand on to the other.
The contributions described thus far address specific subproblems of
the more complex task of autonomous manipulation. This actually differs
from what humans do, in that humans develop their manipulation
skills by learning through experience and trial-and-error strategy. Aproper
mathematical formulation for encoding this learning approach is given by
Deep Reinforcement Learning, that has recently proved to be successful in
many robotics applications. For this reason, in this Thesis we report also
on the six month experience carried out at Berkeley Artificial Intelligence
Research laboratory with the goal of studying Deep Reinforcement Learning
and its application to autonomous manipulation
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