Ashwin Iyer
College of Engineering
Works (12)
Updated: October 16th, 2024 05:01
2024 journal article
Real-Time Ultrasound Imaging of a Human Muscle to Optimize Shared Control in a Hybrid Exoskeleton
IEEE TRANSACTIONS ON ROBOTICS, 40, 4322–4336.
author keywords: Muscles; Fatigue; Iron; Exoskeletons; Legged locomotion; Real-time systems; Torque; Biomedical imaging; electrical stimulation; exoskeletons; neurorehabilitation; optimal control
Sources: Web Of Science, ORCID, NC State University Libraries
Added: October 8, 2024
2023 article
Cooperative Control of a Hybrid Exoskeleton Using Optimal Time Varying Impedance Parameters During Stair Ascent
2023 AMERICAN CONTROL CONFERENCE, ACC, pp. 2739–2744.
Sources: Web Of Science, NC State University Libraries
Added: March 11, 2024
2023 journal article
Dynamic Active Subspaces for Model Predictive Allocation in Over-Actuated Systems
IEEE CONTROL SYSTEMS LETTERS, 8, 145–150.
author keywords: Actuators; Task analysis; Torque; Resource management; Matrix decomposition; System dynamics; Optimal control; Hybrid neuroprosthesis; model predictive control; Koopman operator; control allocation
TL;DR:
To improve computational efficiency of the MPCA, Koopman operator-based linear prediction dynamics of an over-actuated nonlinear robotic system is developed and demonstrated on a hybrid neuroprosthesis model for a trajectory tracking task.
(via Semantic Scholar)
Sources: Web Of Science, ORCID, NC State University Libraries
Added: January 28, 2024
2023 article
Koopman-based Data-driven Model Predictive Control of Limb Tremor Dynamics with Online Model Updating: A Theoretical Modeling and Simulation Approach
2023 AMERICAN CONTROL CONFERENCE, ACC, pp. 2873–2878.
TL;DR:
A Koopman-based method for system identification and its application to the design of a model predictive control (MPC) scheme to suppress tremors and a recursive least squares (RLS) algorithm to improve control performance with low computational complexity are presented.
(via Semantic Scholar)
Sources: Web Of Science, NC State University Libraries
Added: March 11, 2024
2023 article
Nonlinear System Identification of Tremors Dynamics: A Data-driven Approximation Using Koopman Operator Theory
2023 11TH INTERNATIONAL IEEE/EMBS CONFERENCE ON NEURAL ENGINEERING, NER.
TL;DR:
A data-driven method for approximating the Koopman operator is implemented, which is capable of presenting nonlinear dynamics in a linear framework and is promising for predicting the nonlinear system.
(via Semantic Scholar)
Sources: Web Of Science, NC State University Libraries
Added: September 5, 2023
2022 article
A Hybrid Knee Exoskeleton Using Real-Time Ultrasound-Based Muscle Fatigue Assessment
Sheng, Z., Iyer, A., Sun, Z., Kim, K., & Sharma, N. (2022, May 19). IEEE-ASME TRANSACTIONS ON MECHATRONICS, Vol. 5.
Contributors: Z. Sheng *, n, Z. Sun n, K. Kim * & N. Sharma n
author keywords: Muscles; Ultrasonic imaging; Exoskeletons; Switches; Iron; Fatigue; Control systems; Control design; closed loop system; delay system; motion control; nonlinear control system; rehabilitation robotics; robust control; switching systems; state feedback; ultrasonic imaging
TL;DR:
Results from the first experimental demonstration of a hybrid knee exoskeleton that uses ultrasound-derived muscle state feedback to coordinate electrical motors and FES are presented, suggesting a potential application in the rehabilitation of neurological disorders like spinal cord injuries and stroke.
(via Semantic Scholar)
UN Sustainable Development Goal Categories
16. Peace, Justice and Strong Institutions
(OpenAlex)
Sources: Web Of Science, NC State University Libraries, ORCID
Added: June 6, 2022
2022 article
Continuous Switching Control of an Input-Delayed Antagonistic Muscle Pair During Functional Electrical Stimulation
Sun, Z., Qiu, T., Iyer, A., Dicianno, B. E., & Sharma, N. (2022, June 21). IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY, Vol. 6.
Contributors: Z. Sun, T. Qiu*, n, B. Dicianno * & N. Sharma n
author keywords: Muscles; Iron; Switches; Elbow; Control systems; Delays; Recruitment; Antagonistic muscles; delay systems; electromechanical delay (EMD); functional electrical stimulation (FES); Lyapunov-Krasovskii (LK) functionals; Lyapunov stability
TL;DR:
A robust controller is designed to facilitate the FES of an antagonistic muscle pair during elbow flexion and extension by using a continuous switching law that maps a joint angle error to control the antagonism muscle pair.
(via Semantic Scholar)
UN Sustainable Development Goal Categories
16. Peace, Justice and Strong Institutions
(OpenAlex)
Sources: Web Of Science, ORCID, NC State University Libraries
Added: June 22, 2022
2022 journal article
Ultrasound Echogenicity as an Indicator of Muscle Fatigue during Functional Electrical Stimulation
SENSORS, 22(1).
Contributors: Q. Zhang n , n, K. Lambeth n, K. Kim * & N. Sharma n
author keywords: muscle fatigue; electrical stimulation; ankle joint; biomechanical phenomena; ultrasonography; linear models; nonlinear dynamics
MeSH headings : Electric Stimulation; Humans; Isometric Contraction; Muscle Contraction; Muscle Fatigue; Muscle, Skeletal; Ultrasonography
TL;DR:
The findings in this study indicate that the US echogenicity signal is a computationally efficient signal that strongly represents FES-induced muscle fatigue and its potential real-time implementation to detect fatigue can facilitate an FES closed-loop controller design that considers the Fes- induced muscle fatigue.
(via Semantic Scholar)
open access via www.mdpi.com (publisher PDF)
Sources: Web Of Science, ORCID, NC State University Libraries
Added: January 8, 2022
2022 article
Ultrasound Imaging-Based Closed-Loop Control of Functional Electrical Stimulation for Drop Foot Correction
Zhang, Q., Lambeth, K., Iyer, A., Sun, Z., & Sharma, N. (2022, September 30). IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY, Vol. 9.
Contributors: Q. Zhang n , K. Lambeth n, n, Z. Sun n & N. Sharma n
author keywords: Ankle dorsiflexion; drop foot; functional electrical stimulation (FES); nonlinear control; sampled-data observer (SDO); ultrasound (US) imaging
TL;DR:
The use of ultrasound (US) echogenicity as an indicator of FES-evoked muscle activation is explored and a methodology to integrate US in an FES control framework is provided, which will likely benefit persons with drop foot and those with other mobility disorders.
(via Semantic Scholar)
Sources: Web Of Science, ORCID, NC State University Libraries
Added: October 1, 2022
2021 journal article
A Dual-Modal Approach Using Electromyography and Sonomyography Improves Prediction of Dynamic Ankle Movement: A Case Study
IEEE TRANSACTIONS ON NEURAL SYSTEMS AND REHABILITATION ENGINEERING, 29, 1944–1954.
author keywords: Imaging; Sensors; Legged locomotion; Feature extraction; Neuromuscular; Dynamics; Biomedical imaging; B-mode ultrasound imaging; surface electromyography; machine learning regression; dynamic ankle dorsiflexion motion; human limb intent
MeSH headings : Ankle; Ankle Joint; Electromyography; Humans; Movement; Muscle, Skeletal
TL;DR:
The findings show that potentially the dual-modal sensing approach can be used as a superior sensing modality to predict human intent of a continuous motion and implemented for volitional control of clinical rehabilitative and assistive devices.
(via Semantic Scholar)
Sources: Web Of Science, ORCID, NC State University Libraries
Added: September 28, 2021
2021 conference paper
Ultrasound Echogenicity-based Assessment of Muscle Fatigue During Functional Electrical Stimulation
2021 43rd Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC), 5948–5952.
Contributors: Q. Zhang* , *, K. Lambeth*, K. Kim * & N. Sharma*
Event: 43rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society at Mexico on November 1-5, 2021
MeSH headings : Electric Stimulation; Electromyography; Humans; Isometric Contraction; Muscle Fatigue; Ultrasonography
TL;DR:
The findings indicate that US echogenicity may be a promising computationally efficient indicator for assessing FES-induced muscle fatigue and may aid in the design of muscle-in-the-loop FES controllers that consider the onset of muscle fatigue.
(via Semantic Scholar)
Sources: Web Of Science, NC State University Libraries, ORCID
Added: April 25, 2022
2020 journal article
Evaluation of Non-Invasive Ankle Joint Effort Prediction Methods for Use in Neurorehabilitation Using Electromyography and Ultrasound Imaging
IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING, 68(3), 1044–1055.
author keywords: Neuromuscular; Biomedical measurement; Force; Mathematical model; Imaging; Dynamics; Ankle dorsiflexion; electromyography; feedforward neural network; linear regression; neuromuscular model; ultrasound imaging
MeSH headings : Ankle Joint / diagnostic imaging; Electromyography; Humans; Isometric Contraction; Muscle, Skeletal / diagnostic imaging; Neurological Rehabilitation; Ultrasonography
TL;DR:
A comparative study of ultrasound imaging (US)-derived neuromuscular signals and sEMG signals for their use in predicting isometric ankle dorsiflexion moment indicates FFNN or HNM approach and using pennation angle or fascicle length predict human ankle movement intent with higher accuracy.
(via Semantic Scholar)
Sources: Web Of Science, ORCID, NC State University Libraries
Added: March 22, 2021
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