Model-Based Manipulation of Linear Flexible Objects: Task Automation in Simulation and Real World

Peng Chang,Taşkın Padır

doi:10.3390/machines8030046

Abstract

Manipulation of deformable objects is a desired skill in making robots ubiquitous in manufacturing, service, healthcare, and security. Common deformable objects (e.g., wires, clothes, bed sheets, etc.) are significantly more difficult to model than rigid objects. In this research, we contribute to the model-based manipulation of linear flexible objects such as cables. We propose a 3D geometric model of the linear flexible object that is subject to gravity and a physical model with multiple links connected by revolute joints and identified model parameters. These models enable task automation in manipulating linear flexible objects both in simulation and real world. To bridge the gap between simulation and real world and build a close-to-reality simulation of flexible objects, we propose a new strategy called Simulation-to-Real-to-Simulation (Sim2Real2Sim). We demonstrate the feasibility of our approach by completing the Plug Task used in the 2015 DARPA Robotics Challenge Finals both in simulation and real world, which involves unplugging a power cable from one socket and plugging it into another. Numerical experiments are implemented to validate our approach.

Highlights

Manipulation of linear flexible objects is of great interest in many applications including service, manufacturing, health, and disaster response
Our system framework for task automation is evaluated by running the DARPA Robotics Challenge (DRC) Plug Task both in simulation and real world for 20 trials
We proposed a geometrical modeling method based on the curves on two projection planes for linear flexible objects subject to gravity

Summary

Introduction

Manipulation of linear flexible objects is of great interest in many applications including service, manufacturing, health, and disaster response. Ropes, clothes, organs, and strings are common deformable objects used in deformable object manipulation [1,2,3,4,5,6]. Cables are linear flexible objects that are common both in industrial and domestic environments. Popular tasks about linear flexible object manipulation include tying a knot using a rope [7], inserting a string to a hole [8], untangling a rope tie [9], predicting and controlling the shape of the cable [10,11]. Cables are linear flexible objects that are common in industrial, domestic, and nuclear environments. The Plug Task in this challenge required the robot to pull a power cable out of a socket and plug it into another [12]

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Conclusion