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Michael A. Hopkins

6 accepted papers

2026

Olaf: Bringing an Animated Character to Life in the Physical World

RA-L 2026

Animated characters often move in non-physical ways and have proportions that are far from a typical walking robot. This provides an ideal platform for innovation in both mechanical design and stylized motion control. In this letter, we bring Olaf to life in the physical world, relying on reinforcem

Cited by 6SourceScholar
2025

Autonomous Human-Robot Interaction via Operator Imitation

IROS 2025

Teleoperated robotic characters can perform expressive interactions with humans, relying on the operators’ experience and social intuition. In this work, we propose to create autonomous interactive robots, by training a model to imitate operator data. Our model is trained on a dataset of human-robot

Cited by 2SourceScholar
2024

Design and Control of a Bipedal Robotic Character

RSS 2024poster

Legged robots have achieved impressive feats in dynamic locomotion in challenging unstructured terrain. However, in entertainment applications, the design and control of these robots face additional challenges in appealing to human audiences. This work aims to unify expressive, artist-directed motio…

Cited by 11SourcePDFScholar
2015

An unlumped model for linear series elastic actuators with ball screw drives

IROS 2015poster

Series elastic actuators are frequently modeled using a conventional lumped mass model which has remained mostly unchanged since their introduction almost two decades ago. The lumped model has served well for early development but more descriptive models are now needed for new actuator designs and c…

Cited by 45SourceScholar
2015

Compliant locomotion using whole-body control and Divergent Component of Motion tracking

ICRA 2015poster

This paper presents a compliant locomotion framework for torque-controlled humanoids using model-based whole-body control. In order to stabilize the centroidal dynamics during locomotion, we compute linear momentum rate of change objectives using a novel time-varying controller for the Divergent Com…

Cited by 98SourceScholar
2015

Embedded joint-space control of a series elastic humanoid

IROS 2015poster

This paper provides an overview of the embedded joint-space control approach developed for THOR, a new series elastic humanoid. The 60 kg robot features electromechanical linear series elastic actuators (SEAs), enabling low-impedance control of each joint in the lower body via linear to rotary and p…

Cited by 53SourceScholar