Stefanos Nikolaidis

Dr. Stefanos Nikolaidis


Research Focus & Metrics

Academic Career Length

11Years (2016-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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29 July 2021 in IEEE Robotics and Automation Letters
Verified
Journal Article
Closed access
Mario SelvaggioMario Selvaggio
Mario Selvaggio
MCMarco Cognetti
Marco Cognetti
SNStefanos Nikolaidis
Stefanos Nikolaidis
SISerena Ivaldi
Serena Ivaldi
BSBruno Siciliano
Bruno Siciliano
Sharing the control of a robotic system with an autonomous controller allows a human to reduce his/her cognitive and physical workload during the execution of a task. In recent years, the development of inference and learning techniques has widened the spectrum of applications of shared control (SC) approaches, leading to robotic systems that are capable of seamless adaptation of their autonomy level. In this perspective, shared autonomy (SA) can be defined as the design paradigm that enables this adapting behavior of the robotic system. This letter collects the latest results achieved by the research community in the field of SC and SA with special emphasis on physical human-robot interaction (pHRI). Architectures and methods developed for SC and SA are discussed throughout the paper, highlighting the key aspects of each methodology. A discussion about open issues concludes this letter.

14 April 2023 in ACM Transactions on Human-Robot Interaction
Verified
Journal Article
Open access
NDNathaniel Dennler
Nathaniel Dennler
CRChangxiao Ruan
Changxiao Ruan
JHJessica Hadiwijoyo
Jessica Hadiwijoyo
BCBrenna Chen
Brenna Chen
SNStefanos Nikolaidis
Stefanos Nikolaidis
MMMaja Mataric
Maja Mataric
The physical design of a robot suggests expectations of that robot’s functionality for human users and collaborators. When those expectations align with the robot’s true capabilities, users are more likely to adopt the technologies for their intended use. However, the relationship between expectations and socially interactive robot design is not well understood. This article applies the concept of design metaphors to robot design and contributes the Metaphors for Understanding Functional and Social Anticipated Affordances dataset of 165 extant robots and the expectations users place on them. We used Mechanical Turk to crowd-source user expectation over three user studies. The first study ( N = 382) associated crowd-sourced design metaphors to different robot embodiments. The second study ( N = 803) assessed initial social expectations of robot embodiments. The final study ( N = 805) addressed the degree of abstraction of the design metaphors and the functional expectations projected on robot embodiments. We performed analyses to gain insights into how design metaphors can be used to understand social and functional expectations of robots and how these data can be visualized to be useful for study designers and robot designers. Together, these results can serve to guide robot designers toward aligning user expectations with true robot capabilities, facilitating positive human–robot interaction.

12 July 2023
Verified
Conference Paper
Open access
BTBryon Tjanaka
Bryon Tjanaka
MFMatthew C Fontaine
Matthew C Fontaine
DLDavid H Lee
David H Lee
YZYulun Zhang
Yulun Zhang
NBNivedit Reddy Balam
Nivedit Reddy Balam
SNStefanos Nikolaidis
Stefanos Nikolaidis
Recent years have seen a rise in the popularity of quality diversity (QD) optimization, a branch of optimization that seeks to find a collection of diverse, high-performing solutions to a given problem. To grow further, we believe the QD community faces two challenges: developing a framework to represent the field's growing array of algorithms, and implementing that framework in software that supports a range of researchers and practitioners. To address these challenges, we have developed pyribs, a library built on a highly modular conceptual QD framework. By replacing components in the conceptual framework, and hence in pyribs, users can compose algorithms from across the QD literature; equally important, they can identify unexplored algorithm variations. Furthermore, pyribs makes this framework simple, flexible, and accessible, with a user-friendly API supported by extensive documentation and tutorials. This paper overviews the creation of pyribs, focusing on the conceptual framework that it implements and the design principles that have guided the library's development. Pyribs is available at https://pyribs.org

10 May 2022 in IEEE Transactions on Haptics
Verified
Journal Article
Closed access
SLShihan Lu
Shihan Lu
MZMianlun Zheng
Mianlun Zheng
MFMatthew C. Fontaine
Matthew C. Fontaine
SNStefanos Nikolaidis
Stefanos Nikolaidis
HCHeather Marie Culbertson
Heather Marie Culbertson
Data-driven texture modeling and rendering has pushed the limit of realism in haptics. However, the lack of haptic texture databases, difficulties of model interpolation and expansion, and the complexity of real textures prevent data-driven methods from capturing a large variety of textures and from customizing models to suit specific output hardware or user needs. This work proposes an interactive texture generation and search framework driven by user input. We design a GAN-based texture model generator, which can create a wide range of texture models using Auto-Regressive processes. Our interactive texture search method, which we call preference-driven, follows an evolutionary strategy given guidance from user's preferred feedback within a set of generated texture models. We implemented this framework on a 3D haptic device and conducted a two-phase user study to evaluate the efficiency and accuracy of our method for previously unmodeled textures. The results showed that by comparing the feel of real and generated virtual textures, users can follow an evolutionary process to efficiently find a virtual texture model that matched or exceeded the realism of a data-driven model. Furthermore, for 4 out of 5 real textures, 80% of the preference-driven models from participants were rated comparable to the data-driven models.

25 June 2021 in IEEE Robotics and Automation Letters
Verified
Journal Article
Closed access
APAniruddh G. Puranic
Aniruddh G. Puranic
JDJyotirmoy V. Deshmukh
Jyotirmoy V. Deshmukh
SNStefanos Nikolaidis
Stefanos Nikolaidis
Learning control policies that are safe, robust and interpretable are prominent challenges in developing robotic systems. Learning-from-demonstrations with formal logic is an arising paradigm in reinforcement learning to estimate rewards and extract robot control policies that seek to overcome these challenges. In this approach, we assume that mission-level specifications for the robotic system are expressed in a suitable temporal logic such as Signal Temporal Logic (STL). The main idea is to automatically infer rewards from user demonstrations (that could be suboptimal or incomplete) by evaluating and ranking them w.r.t. the given STL specifications. In contrast to existing work that focuses on deterministic environments and discrete state spaces, in this letter, we propose significant extensions that tackle stochastic environments and continuous state spaces.

12 July 2023
Verified
Conference Paper
Open access
MFMatthew Fontaine
Matthew Fontaine
SNStefanos Nikolaidis
Stefanos Nikolaidis
Single-objective optimization algorithms search for the single highest-quality solution with respect to an objective. Quality diversity (QD) optimization algorithms, such as Covariance Matrix Adaptation MAP-Elites (CMA-ME), search for a collection of solutions that are both high-quality with respect to an objective and diverse with respect to specified measure functions. However, CMA-ME suffers from three major limitations highlighted by the QD community: prematurely abandoning the objective in favor of exploration, struggling to explore flat objectives, and having poor performance for low-resolution archives. We propose a new quality diversity algorithm, Covariance Matrix Adaptation MAP-Annealing (CMA-MAE), that addresses all three limitations. We provide theoretical justifications for the new algorithm with respect to each limitation. Our theory informs our experiments, which support the theory and show that CMA-MAE achieves state-of-the-art performance and robustness.