Publications

Journal

G. C. Thomas, O. Campbell IV, N. Nichols, N. Brissonneau, B. He, J. James, N. Paine, and L. Sentis, "Formulating and Deploying Strength Amplification Controllers for Lower-Body Walking Exoskeletons," Frontiers in Robotics and AI, vol. 8, pp. 295, Sept. 2021. [pdf] [Frontiers]

R. L. Medrano, G. C. Thomas, E. J. Rouse, R. D. Gregg, “Analysis of the Bayesian Gait-State Estimation Problem for Lower-Limb Wearable Robot Sensor Configurations,” IEEE Robotics and Automation Letters, vol. 7, no. 3, pp. 7463 - 7470, July 2022, doi: 10.1109/LRA.2022.3183790. [IEEE] [pdf]

C. Nesler, G. C. Thomas, N. Divekar, E. J. Rouse, R. D. Gregg, “Enhancing Voluntary Motion with Modular, Backdrivable, Powered Hip and Knee Orthoses,” IEEE Robotics and Automation Letters, vol. 7, no. 3, pp. 6155-6162, July 2022, doi: 10.1109/LRA.2022.3145580. [IEEE] [pdf]

J. Lin, N. V. Divekar, G. C. Thomas, R. D. Gregg, “Optimally Biomimetic Passivity-Based Control of a Lower-Limb Exoskeleton Over the Primary Activities of Daily Life,” IEEE Open Journal of Control Systems, vol. 1, pp. 15 - 28, April 2022, doi: 10.1109/OJCSYS.2022.3165733. [IEEE] [pdf]

R. L. Medrano, G. C. Thomas, E. Rouse, “Can humans perceive the metabolic benefit provided by augmentative exoskeletons?” Journal of NeuroEngineering and Rehabilitation, vol 19, no. 26, February 2022, doi: 10.1186/s12984-022-01002-w [Springer] [pdf]

R. L. Medrano, E. Rouse, G. C. Thomas, "Biological Joint Loading and Exoskeleton Design," IEEE Transactions on Medical Robotics and Bionics, vol. 3, no. 3, pp. 847-851, Aug. 2021. [IEEE] [pdf] [CodeOcean]

N. Brissonneau, B. He, G. C. Thomas, and L. Sentis, "Biologically-Inspired Impedance Control with Hysteretic Damping," IEEE Control Systems Letters, vol. 5, no. 5, pp. 1717-1722, Nov. 2021. (early access) [IEEE] [pdf]

G. C. Thomas, J. Mehling, J. Holley, and L. Sentis, "Phase-Relaxed-Passive Full State Feedback Gain Limits for Series Elastic Actuators," IEEE/ASME Transactions on Mechatronics, vo. 26, no. 1, pp. 586-591, Feb. 2021. [IEEE] [pdf]

B. He, H. Huang, G. C. Thomas, and L. Sentis, "A Complex Stiffness Human Impedance Model with Customizable Exoskeleton Control," IEEE Transactions on Neural Systems and Rehabilitation Engineering, vol. 28, no. 11, pp. 2468-2477, Nov. 2020. [ArXiv] [IEEE]

G. C. Thomas, and L. Sentis, "Quadric Inclusion Programs: an LMI Approach to H[infinity]-Model Identification," IEEE Transactions on Automatic Control, vol. 64, no. 10, pp. 4229-4236, Oct. 2019. [doi] [IEEE] [CodeOcean] [ArXiv]

K. Isik, G. C. Thomas, and L. Sentis, "A Fixed Structure Gain Selection Strategy for High Impedance Series Elastic Actuator Behavior," Journal of Dynamic Systems, Measurement, and Control, vol. 141, no. 2, Oct. 2018, doi: 10.1115/1.4041449. [ASME]

D. Kim, Y. Zhao, G. C. Thomas, and L. Sentis, "Stabilizing Series-Elastic Point-Foot Bipeds Using Whole-Body Operational Space Control," IEEE Transactions on Robotics, vol. 32, no. 6, pp. 1362-1379, Dec. 2016. [Finalist, Best WBC Paper 2016][Finalist, Best WBC-Video 2016][doi][IEEE][pdf]

T. Koolen, S. Bertrand, G. C. Thomas, T. de Boer, T. Wu, J. Smith, J. Englsberger, and J. E. Pratt, "Design of a Momentum-Based Control Framework and Application to the Humanoid Robot Atlas," International Journal of Humanoid Robotics, vol. 13, no. 1, pp. 1650007, Mar. 2016. [Winner, IJHR 2016 Best Paper Awards][Finalist, Best WBC Paper 2016][IJHR]

Conference

G. C. Thomas, R. D. Gregg, "An Energy Shaping Exoskeleton Controller for Human Strength Amplification,” in The 2021 IEEE Conference on Decision and Control, pp. 1419-1425, doi: 10.1109/CDC45484.2021.9682793 [pdf] [IEEE]

E. Bolívar-Nieto, G. C. Thomas, E. Rouse, R. D. Gregg, "Convex Optimization for Spring Design in Series Elastic Actuators: From Theory to Practice," in the 2021 IEEE/RSJ International Conference on Intelligent Robotics and Systems, pp. 9327-9332, 2021. [pdf]

R. Medrano, G. C. Thomas, and E. Rouse. "Methods for Measuring the Just Noticeable Difference for Variable Stimuli: Implications for Perception of Metabolic Rate with Exoskeleton Assistance." in The 8th IEEE RAS/EMBS International Conference for Biomedical Robotics and Biomechatronics, pp. 483-490, New York City, NY, 2020. [IEEE]

B. He, G. C. Thomas, and L. Sentis. "Robust Estimator-Based Safety Verification: A Vector Norm Approach." In The 2020 American Control Conference, pp. 3419-3424. [ArXiv] [IEEE]

H. Huang, H. Cappel, G. C. Thomas, B. He, and L. Sentis. "Adaptive Compliance Shaping with Human Impedance Estimation." In The 2020 American Control Conference, pp. 3419-3424. [ArXiv] [IEEE]

G. C. Thomas, J. M. Coholich, and L. Sentis. "Compliance Shaping for Control of Strength Amplification Exoskeletons with Elastic Cuffs." Presented at The 2019 IEEE/ASME International Conference on Advanced Intelligent Mechatronics, Hong Kong, China, pp. 1199-1206. IEEE, 2019. [IEEE] [ArXiv]

B. He, H. Huang, G. C. Thomas, and L. Sentis. "Complex Stiffness Model of Physical Human-Robot Interaction: Implications for Control of Performance Augmentation Exoskeletons." In The 2019 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), Macau, China, pp. 6748-6755. IEEE, 2019. [IEEE] [doi] [ArXiv]

B. He, G. C. Thomas, N. A. Paine, and L. Sentis. "Modeling and Loop Shaping of Single-Joint Amplification Exoskeleton with Contact Sensing and Series Elastic Actuation." In The 2019 American Control Conference, Philadelphia, PA, pp. 4580-4587. IEEE, 2019. [IEEE] [ArXiv]

R. Schlossman, G. C. Thomas, O. Campbell, and L. Sentis, "Toward Exploiting the Natural Dynamics of Series Elastic Robots by Actuator-Centered Sequential Linear Program," The IEEE International Conference on Robotics and Biomimetics, Kuala Lumpur, Malaysia, 2018 [IEEE] [ArXiv]

G. C. Thomas, B. He, and L. Sentis, "Safety Control Synthesis with Input Limits: a Hybrid Approach," The American Control Conference, Milwaukee, WI, 2018 [IEEE] [ArXiv]

G. C. Thomas, and L. Sentis, "MIMO Identification of Frequency-Domain Unreliability in SEAs," The American Control Conference, Seattle, WA, 2017 [IEEE][pdf]

P. Rao, G. C. Thomas, L. Sentis, and A. Deshpande "Analyzing Achievable Stiffness Control Bounds of Robotic Hands With Coupled Finger Joints," IEEE Conference on Robotics and Automation, Singapore, 2017 [Winner, Best ICRA 2017 Manipulation Paper] [IEEE] [pdf]

G. C. Thomas, and L. Sentis, "Towards Computationally Efficient Planning of Dynamic Multi-Contact Locomotion," in The IEEE/RSJ International Conference on Intelligent Robots and Systems, Daejeon, South Korea, 2016, doi: 10.1109/IROS.2016.7759571 [IEEE] [pdf]

D. Kim, G. C. Thomas, and L. Sentis, "A Method for Dynamically Balancing a Point Foot Robot," in The 15th IEEE-RAS International Conference on Humanoid Robots, 2015, doi: 10.1109/HUMANOIDS.2015.7363468 [IEEE] [pdf]

D. Kim, G. C. Thomas, and L. Sentis, "Continuous Cyclic Stepping on 3D Point-Foot Biped Robots Via Constant Time to Velocity Reversal," in Control Automation Robotics & Vision (ICARCV), 2014 13th International Conference on., IEEE. 2014, doi: 10.1109/ICARCV.2014.7064561 [IEEE]

D. Kim, Y. Zhao, G. C. Thomas, and L. Sentis, "Empirical Modifications to a Phase Space Planner which Compensates for Low Stiffness Actuation in a Planar, Point-Foot, Biped Robot," in ASME 2014 Dynamics Systems and Control Conference, San Antonio, TX, 2014, doi: 10.1115/DSCC2014-6033 [ASME]

K.S. Kim, G. C. Thomas, and L. Sentis, "Fully Omnidirectional Compliance in Mobile Robots Via Drive-Torque Sensor Feedback" in IEEE International Conference of Intelligent Robots and Systems, 2014, doi: 10.1109/IROS.2014.6943239 [IEEE] [pdf]

T. Koolen, J. Smith, G. C. Thomas, S. Bertrand, J. Carff, N. Mertins, D. Stephen et al., "Summary of team IHMC’s virtual robotics challenge entry," in Proceedings of the IEEE-RAS International Conference on Humanoid Robots, 2013, doi: 10.1109/HUMANOIDS.2013.7029992 [IEEE]

G. C. Thomas, C. Gimenez, E. Chin, A. Carmedelle, and A. M. Hoover, "Controllable, High Force Amplification Using Elastic Cable Capstans," in ASME 2012 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference Volume 4: 36th Mechanisms and Robotics Conference, Parts A and B., Chicago, IL, 2012, pp.885-889. [ASME] [pdf]

E. Culler, G. C. Thomas, and C. L. Lee, "A Perching Landing Gear for a Quadcopter," in 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference, Structures, Structural Dynamics, and Materials and Co-located Conferences., Honolulu, HI, 2012, doi: 10.2514/6.2012-1722 [AIAA]

Oral

I. Olaru, C. Schmidt-Wetekam, N. Payton, G. C. Thomas, J. Godowski, J. Pratt and S. Cotton, "Mechanical Design of the FastRunner Leg," at International Conference on Robotics and Automation: Orals and Tutorials, Design and Control of High-Performance Hydraulic Robots: Recent Advances and Perspectives, 2013 [Talk]

Poster

G. C. Thomas, and E. Rouse, "Stiffening Cantilever-Disk Springs for the OSL," at Dynamic Walking, 2021 [abstract]

R. L. Medrano, G. C. Thomas, and E. Rouse, "Measuring the Just Noticeable Difference of Metabolic Rate with Exoskeleton Assistance," at Dynamic Walking, 2021 [abstract]

J. A. Montes Pérez, G. C. Thomas, and R. D. Gregg, "Low-Dimensional Individualized Continuous-Task Joint Kinematic Modelling," at Dynamic Walking, 2021 [abstract]

G. C. Thomas, J. Lin, N. Divekar, C. Nestler, R. D. Gregg, "Task-Invariant Assistance using Backdrivable, Powered Orthoses," at NIH Rehabilitation Research 2020: Envisioning a Functional Future, October 2020 [poster]

R. L. Medrano, G. C. Thomas, and E. Rouse, "Quantifying Perception of Metabolic Changes from Exoskeleton Assistance," at Dynamic Walking, May 2020 [pdf]

G. C. Thomas, and L. Sentis, "Monte Carlo UQ for Control Systems With Convex Optimization" (Originally: "Identifying Bounded Uncertainty Models with Convex Optimization"), at Uncertainty Quantification and Data-Driven Modeling, Austin, Texas, 2017 [conference][pdf]

G. C. Thomas, and L. Sentis, "Identification of Frequency-Domain Uncertainty for Series Elastic Actuators," in IROS 2016 Workshop on The Mechatronics behind Force/Torque Controlled Robot Actuation: Secrets and Challenges, Daejeon, South Korea, 2016 [pdf]

Y. Zhao, D. Kim, G. C. Thomas, and L. Sentis, "Hybrid Multi-Contact Dynamics for Wedge Jumping Locomotion Behaviors," in Proceedings of the 18th International Conference on Hybrid Systems: Computation and Control, 2015, doi: 10.1145/2728606.2728645 [Link]

D.H. Kim, Y. Zhao, G. C. Thomas, and L. Sentis, "Towards Agility in Compliant Point-Foot Bipeds," at Dynamic Walking, June 2014 [pdf]

Other

G. C. Thomas, N. Hobbs. "Using LabVIEW to Rapidly Build an Autonomous Robot and Compete in the Intelligent Ground Vehicle Competition", National Instruments Case Study http://sine.ni.com/cs/app/doc/p/id/cs-13114

G. C. Thomas, M. Alvarado, L. Hill, J. McCandless, J. Regulinski, V. Mani, C. Marra, T. Lamar, N. Hobbs. "Dave: Franklin W. Olin College of Engineering 2011 Intelligent Ground Vehicle Competition Entry" Design Report, Intelligent Ground Vehicle Competition, 2011, Oakland University in Rochester, Michigan.

N. Hobbs, R. Cherney, D. Grieneisen, J. Izraelevitz, G. C. Thomas, J. Noglows, E. Kolker, L. Hill. "Athena: Franklin W. Olin College of Engineering 2010 Intelligent Ground Vehicles Competition Entry" Design Report, Intelligent Ground Vehicle Competition, 2010, Oakland University in Rochester, Michigan.