Braking Control in Clutched-Elastic Robots: Coordinating the Underactuation-to-Actuation Transition
Vasilije Rakcevic, Dennis Ossadnik, Edmundo Pozo Fortunic, Mehmet Can Yildirim, Valentin Le Mesle, Sami Haddadin
Abstract
Robots with intrinsic joint elasticity can perform highly dynamic manoeuvres by leveraging energy storage and release, enabling explosive motions such as throwing. By augmenting elastic robots with clutch mechanisms, link decoupling can be used to fully exploit inertial coupling effects and gravitational acceleration in motion while effectively circumventing spring deflection limits. However, braking such systems in a decoupled state presents a challenge, as re-engaging the link risks damaging the joint. While optimal control strategies could be applied, they are not inherently safe due to model uncertainties. To address this, we propose a feedback-based two-stage method that coordinates the transition through the hybrid modes of the system. These modes are characterized by underactuated and actuated dynamics. First, a decoupled link is braked via inertial coupling until a safe velocity for clutching is reached, after which the link is re-coupled and actively braked. We demonstrate the effectiveness of this method through simulations comparing it with optimal control and validate it experimentally using a physical prototype.
BibTeX
@inproceedings{iros2025_brakingcontrolin,
title = {Braking Control in Clutched-Elastic Robots: Coordinating the Underactuation-to-Actuation Transition},
author = {Vasilije Rakcevic and Dennis Ossadnik and Edmundo Pozo Fortunic and Mehmet Can Yildirim and Valentin Le Mesle and Sami Haddadin},
booktitle = {IROS 2025},
year = {2025}
}