Accurate Simulation and Parameter Identification of Deformable Linear Objects using Discrete Elastic Rods in Generalized Coordinates

TL;DR

This paper introduces a fast, accurate DLO simulation model integrated into MuJoCo, with a novel parameter identification pipeline for bending and twisting stiffness, validated through real-world comparisons.

Contribution

It presents an improved DLO model using Discrete Elastic Rods integrated into MuJoCo, along with a new parameter identification method for stiffness estimation.

Findings

Enhanced accuracy over MuJoCo's native cable model

Effective parameter identification pipeline for DLO stiffness

Validated simulation results closely match real-world DLO behavior

Abstract

This paper presents a fast and accurate model of a deformable linear object (DLO) -- e.g., a rope, wire, or cable -- integrated into an established robot physics simulator, MuJoCo. Most accurate DLO models with low computational times exist in standalone numerical simulators, which are unable or require tedious work to handle external objects. Based on an existing state-of-the-art DLO model -- Discrete Elastic Rods (DER) -- our implementation provides an improvement in accuracy over MuJoCo's own native cable model. To minimize computational load, our model utilizes force-lever analysis to adapt the Cartesian stiffness forces of the DER into its generalized coordinates. As a key contribution, we introduce a novel parameter identification pipeline designed for both simplicity and accuracy, which we utilize to determine the bending and twisting stiffness of three distinct DLOs. We then evaluate the performance of each model by simulating the DLOs and comparing them to their real-world counterparts and against theoretically proven validation tests.