665 research outputs found
Data-driven robotic manipulation of cloth-like deformable objects : the present, challenges and future prospects
Manipulating cloth-like deformable objects (CDOs) is a long-standing problem in the robotics community. CDOs are flexible (non-rigid) objects that do not show a detectable level of compression strength while two points on the article are pushed towards each other and include objects such as ropes (1D), fabrics (2D) and bags (3D). In general, CDOs’ many degrees of freedom (DoF) introduce severe self-occlusion and complex state–action dynamics as significant obstacles to perception and manipulation systems. These challenges exacerbate existing issues of modern robotic control methods such as imitation learning (IL) and reinforcement learning (RL). This review focuses on the application details of data-driven control methods on four major task families in this domain: cloth shaping, knot tying/untying, dressing and bag manipulation. Furthermore, we identify specific inductive biases in these four domains that present challenges for more general IL and RL algorithms.Publisher PDFPeer reviewe
Survey on model-based manipulation planning of deformable objects
A systematic overview on the subject of model-based manipulation planning of deformable objects is presented. Existing modelling techniques of volumetric, planar and linear deformable objects are described, emphasizing the different types of deformation. Planning strategies are categorized according to the type of manipulation goal: path planning, folding/unfolding, topology modifications and assembly. Most current contributions fit naturally into these categories, and thus the presented algorithms constitute an adequate basis for future developments.Preprin
DeRi-IGP: Manipulating Rigid Objects Using Deformable Objects via Iterative Grasp-Pull
Heterogeneous systems manipulation, i.e., manipulating rigid objects via
deformable (soft) objects, is an emerging field that remains in its early
stages of research. Existing works in this field suffer from limited action and
operational space, poor generalization ability, and expensive development. To
address these challenges, we propose a universally applicable and effective
moving primitive, Iterative Grasp-Pull (IGP), and a sample-based framework,
DeRi-IGP, to solve the heterogeneous system manipulation task. The DeRi-IGP
framework uses local onboard robots' RGBD sensors to observe the environment,
comprising a soft-rigid body system. It then uses this information to
iteratively grasp and pull a soft body (e.g., rope) to move the attached rigid
body to a desired location. We evaluate the effectiveness of our framework in
solving various heterogeneous manipulation tasks and compare its performance
with several state-of-the-art baselines. The result shows that DeRi-IGP
outperforms other methods by a significant margin. In addition, we also
demonstrate the advantage of the large operational space of IGP in the
long-distance object acquisition task within both simulated and real
environments
Robotic Picking of Tangle-prone Materials (with Applications to Agriculture).
The picking of one or more objects from an unsorted pile continues to be non-trivial for robotic systems. This is especially so when the pile consists of individual items that tangle with one another, causing more to be picked out than desired. One of the key features of such tangling-prone materials (e.g., herbs, salads) is the presence of protrusions (e.g., leaves) extending out from the main body of items in the pile.This thesis explores the issue of picking excess mass due to entanglement such as occurs in bins composed of tangling-prone materials (TPs), especially in the context of a one-shot mass-constrained robotic bin-picking task. Specifically, it proposes a human-inspired entanglement reduction method for making the picking of TPs more predictable. The primary approach is to directly counter entanglement through pile interaction with an aim of reducing it to a level where the picked mass is predictable, instead of avoiding entanglement by picking from collision or entanglement-free points or regions. Taking this perspective, several contributions are presented that (i) improve the understanding of the phenomenon of entanglement and (ii) reduce the picking error (PE) by effectively countering entanglement in a TP pile.First, it studies the mechanics of a variety of TPs improving the understanding of the phenomenon of entanglement as observed in TP bins. It reports experiments with a real robot in which picking TPs with different protrusion lengths (PLs) results in up to a 76% increase in picked mass variance, suggesting PL be an informative feature in the design of picking strategies. Moreover, to counter the inherent entanglement in a TP pile, it proposes a new Spread-and-Pick (SnP) approach that significantly reduces entanglement, making picking more consistent. Compared to prior approaches that seek to pick from a tangle-free point in the pile, the proposed method results in a decrease in PE of up to 51% and shows good generalisation to previously unseen TPs
Multi-Stage Cable Routing through Hierarchical Imitation Learning
We study the problem of learning to perform multi-stage robotic manipulation
tasks, with applications to cable routing, where the robot must route a cable
through a series of clips. This setting presents challenges representative of
complex multi-stage robotic manipulation scenarios: handling deformable
objects, closing the loop on visual perception, and handling extended behaviors
consisting of multiple steps that must be executed successfully to complete the
entire task. In such settings, learning individual primitives for each stage
that succeed with a high enough rate to perform a complete temporally extended
task is impractical: if each stage must be completed successfully and has a
non-negligible probability of failure, the likelihood of successful completion
of the entire task becomes negligible. Therefore, successful controllers for
such multi-stage tasks must be able to recover from failure and compensate for
imperfections in low-level controllers by smartly choosing which controllers to
trigger at any given time, retrying, or taking corrective action as needed. To
this end, we describe an imitation learning system that uses vision-based
policies trained from demonstrations at both the lower (motor control) and the
upper (sequencing) level, present a system for instantiating this method to
learn the cable routing task, and perform evaluations showing great performance
in generalizing to very challenging clip placement variations. Supplementary
videos, datasets, and code can be found at
https://sites.google.com/view/cablerouting
Sim2Real Neural Controllers for Physics-based Robotic Deployment of Deformable Linear Objects
Deformable linear objects (DLOs), such as rods, cables, and ropes, play
important roles in daily life. However, manipulation of DLOs is challenging as
large geometrically nonlinear deformations may occur during the manipulation
process. This problem is made even more difficult as the different deformation
modes (e.g., stretching, bending, and twisting) may result in elastic
instabilities during manipulation. In this paper, we formulate a physics-guided
data-driven method to solve a challenging manipulation task -- accurately
deploying a DLO (an elastic rod) onto a rigid substrate along various
prescribed patterns. Our framework combines machine learning, scaling analysis,
and physical simulations to develop a physics-based neural controller for
deployment. We explore the complex interplay between the gravitational and
elastic energies of the manipulated DLO and obtain a control method for DLO
deployment that is robust against friction and material properties. Out of the
numerous geometrical and material properties of the rod and substrate, we show
that only three non-dimensional parameters are needed to describe the
deployment process with physical analysis. Therefore, the essence of the
controlling law for the manipulation task can be constructed with a
low-dimensional model, drastically increasing the computation speed. The
effectiveness of our optimal control scheme is shown through a comprehensive
robotic case study comparing against a heuristic control method for deploying
rods for a wide variety of patterns. In addition to this, we also showcase the
practicality of our control scheme by having a robot accomplish challenging
high-level tasks such as mimicking human handwriting, cable placement, and
tying knots.Comment: YouTube video: https://youtu.be/OSD6dhOgyMA?feature=share
- …