Departmental Papers (ESE)



This paper examines the design of a parallel spring-loaded actuated linkage intended for dynamically dexterous legged robotics applications. Targeted at toe placement in the sagittal plane, the mechanism applies two direct-drive brushless dc motors to a symmetric five bar linkage arranged to power free tangential motion and compliant radial motion associated with running, leaping, and related agile locomotion behaviors. Whereas traditional leg design typically decouples the consideration of motor sizing, kinematics and compliance, we examine their conjoined influence on three key characteristics of the legged locomotion cycle: transducing battery energy to body energy during stance; mitigating collision losses upon toe touchdown; and storing and harvesting prior body energy in the spring during stance. This analysis leads to an unconventional design whose “knee” joint rides above the “hip” joint. Experiments demonstrate that the resulting mechanism can deliver more than half again as much kinetic energy to the body (or more than double the kinetic energy if the full workspace is used), and offers a five-fold increase in energy storage and collision efficiency relative to the conventional design.

Sponsor Acknowledgements

This work was supported by US Army Research Laboratory under Cooperative Agreement Number W911NF-10-2-0016 and Fonds de Recherche du Quebec, Nature et Technologies dossier 168461.

Document Type

Conference Paper

Subject Area

GRASP, Kodlab

Date of this Version


Publication Source

IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)




robot, legged robot, leg design, robot design

Bib Tex

author={G. Kenneally and D. E. Koditschek},
booktitle={2015 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)},
title={Leg design for energy management in an electromechanical robot},
keywords={brushless DC motors;control system synthesis;electromechanical actuators;energy management systems;legged locomotion;robot kinematics;body energy harvesting;body energy storing;compliance;direct-drive brushless DC motors;dynamically dexterous legged robotics applications;electromechanical robot;energy management;hip joint;kinematics;kinetic energy;knee joint;leaping agile locomotion behaviors;leg design;legged locomotion cycle;mitigating collision losses;motor sizing;parallel spring-loaded actuated linkage;power free tangential motion;radial motion;related agile locomotion behaviors;running agile locomotion behaviors;sagittal plane;symmetric five bar linkage;toe placement;toe touchdown;transducing battery energy;Actuators;Kinematics;Kinetic energy;Robots;Springs;Windings;Wires},



Date Posted: 20 October 2017

This document has been peer reviewed.