@article{shah_fleming_nalam_liu_huang_2022, title={Design of EMG-driven Musculoskeletal Model for Volitional Control of a Robotic Ankle Prosthesis}, volume={2022-October}, ISSN={["2153-0858"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85146352781&partnerID=MN8TOARS}, DOI={10.1109/IROS47612.2022.9981305}, abstractNote={Existing robotic lower-limb prostheses use autonomous control to address cyclic, locomotive tasks, but are inadequate in adapting to variations in non-cyclic and unpredictable tasks. This study aims to address this challenge by designing a novel electromyography (EMG)-driven musculoskeletal model for volitional control of a robotic ankle-foot prosthesis. The proposed controller ensures continuous control of the device, allowing users to freely manipulate the prosthesis behavior. A Hill-type muscle model was implemented to model a dorsiflexor and a plantarflexor to function around a virtual ankle joint. The model parameters for a subject specific model was determined by fitting the model to the experimental data collected from an able-bodied subject. EMG signals recorded from antagonist muscle pairs were used to activate the virtual muscle models. This model-based approach was then validated via offline simulations and real-time prosthesis control. Additionally, the feasibility of the proposed prosthesis control on assisting the user's functional tasks was demonstrated. The present control may further improve the function of robotic prosthesis for supporting versatile activities in individuals with lower-limb amputations.}, journal={2022 IEEE/RSJ INTERNATIONAL CONFERENCE ON INTELLIGENT ROBOTS AND SYSTEMS (IROS)}, author={Shah, Chinmay and Fleming, Aaron and Nalam, Varun and Liu, Ming and Huang, He}, year={2022}, pages={12261–12266} }
 @article{liu_fleming_lee_huang_2021, title={Direct Myoelectric Control Modifies Lower Limb Functional Connectivity: A Case Study}, ISSN={["1558-4615"]}, url={http://dx.doi.org/10.1109/embc46164.2021.9630844}, DOI={10.1109/EMBC46164.2021.9630844}, abstractNote={Prostheses with direct EMG control could restore amputee’s biomechanics structure and residual muscle functions by using efferent signals to drive prosthetic ankle joint movements. Because only feedforward control is restored, it is unclear 1) what neuromuscular control mechanisms are used in coordinating residual and intact muscle activities and 2) how this mechanism changes over guided training with the prosthetic ankle. To address these questions, we applied functional connectivity analysis to an individual with unilateral lower-limb amputation during postural sway task. We built functional connectivity networks of surface EMGs from eleven lower-limb muscles during three sessions to investigate the coupling among different function modules. We observed that functional network was reshaped by training and we identified a stronger connection between residual and intact below knee modules with improved bilateral symmetry after amputee acquired skills to better control the powered prosthetic ankle. The evaluation session showed that functional connectivity was largely preserved even after nine months interval. This preliminary study might inform a unique way to unveil the potential neuromechanic changes that occur after extended training with direct EMG control of a powered prosthetic ankle.}, journal={2021 43RD ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE & BIOLOGY SOCIETY (EMBC)}, publisher={IEEE}, author={Liu, Wentao and Fleming, Aaron and Lee, I-Chieh and Huang, He Helen}, year={2021}, pages={6573–6576} }
 @misc{fleming_stafford_huang_hu_ferris_huang_2021, title={Myoelectric control of robotic lower limb prostheses: a review of electromyography interfaces, control paradigms, challenges and future directions}, volume={18}, ISSN={["1741-2552"]}, url={http://dx.doi.org/10.1088/1741-2552/ac1176}, DOI={10.1088/1741-2552/ac1176}, abstractNote={Objective.Advanced robotic lower limb prostheses are mainly controlled autonomously. Although the existing control can assist cyclic movements during locomotion of amputee users, the function of these modern devices is still limited due to the lack of neuromuscular control (i.e. control based on human efferent neural signals from the central nervous system to peripheral muscles for movement production). Neuromuscular control signals can be recorded from muscles, called electromyographic (EMG) or myoelectric signals. In fact, using EMG signals for robotic lower limb prostheses control has been an emerging research topic in the field for the past decade to address novel prosthesis functionality and adaptability to different environments and task contexts. The objective of this paper is to review robotic lower limb Prosthesis control via EMG signals recorded from residual muscles in individuals with lower limb amputations.Approach.We performed a literature review on surgical techniques for enhanced EMG interfaces, EMG sensors, decoding algorithms, and control paradigms for robotic lower limb prostheses.Main results.This review highlights the promise of EMG control for enabling new functionalities in robotic lower limb prostheses, as well as the existing challenges, knowledge gaps, and opportunities on this research topic from human motor control and clinical practice perspectives.Significance.This review may guide the future collaborations among researchers in neuromechanics, neural engineering, assistive technologies, and amputee clinics in order to build and translate true bionic lower limbs to individuals with lower limb amputations for improved motor function.}, number={4}, journal={JOURNAL OF NEURAL ENGINEERING}, publisher={IOP Publishing}, author={Fleming, Aaron and Stafford, Nicole and Huang, Stephanie and Hu, Xiaogang and Ferris, Daniel P. and Huang, He}, year={2021}, month={Aug} }
 @article{tabor_agcayazi_fleming_thompson_kapoor_liu_lee_huang_bozkurt_ghosh_2021, title={Textile-Based Pressure Sensors for Monitoring Prosthetic-Socket Interfaces}, volume={21}, ISSN={["1558-1748"]}, url={https://doi.org/10.1109/JSEN.2021.3053434}, DOI={10.1109/JSEN.2021.3053434}, abstractNote={Amputees are prone to experiencing discomfort when wearing their prosthetic devices. As the amputee population grows this becomes a more prevalent and pressing concern. There is a need for new prosthetic technologies to construct more comfortable and well-fitted liners and sockets. One of the well-recognized impediments to the development of new prosthetic technology is the lack of practical inner socket sensors to monitor the inner socket environment (ISE), or the region between the residual limb and the socket. Here we present a capacitive pressure sensor fabricated through a simple, and scalable sewing process using commercially available conductive yarns and textile materials. This fully-textile sensor provides a soft, flexible, and comfortable sensing system for monitoring the ISE. We provide details of our low-power sensor system capable of high-speed data collection from up to four sensor arrays. Additionally, we demonstrate two custom set-ups to test and validate the textile-based sensors in a simulated prosthetic environment. Finally, we utilize the textile-based sensors to study the ISE of a bilateral transtibial amputee. Results indicate that the textile-based sensors provide a promising potential for seamlessly monitoring the ISE.}, number={7}, journal={IEEE SENSORS JOURNAL}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Tabor, Jordan and Agcayazi, Talha and Fleming, Aaron and Thompson, Brendan and Kapoor, Ashish and Liu, Ming and Lee, Michael Y. and Huang, He and Bozkurt, Alper and Ghosh, Tushar K.}, year={2021}, month={Apr}, pages={9413–9422} }
 @article{fleming_huang_huang_2019, title={Proportional Myoelectric Control of a Virtual Inverted Pendulum Using Residual Antagonistic Muscles: Toward Voluntary Postural Control}, volume={27}, ISSN={["1558-0210"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85068905602&partnerID=MN8TOARS}, DOI={10.1109/TNSRE.2019.2922102}, abstractNote={This paper aims to investigate whether transtibial amputees are capable of coordinating the descending neural commands to antagonistic residual ankle muscles for performing dynamic tasks that require continuous, precise control. To achieve this goal, we developed a virtual inverted pendulum that was inherently unstable and mimicked human-like dynamics in a standing posture. Balancing this dynamic system requires continuous inputs, proportional to electromyography (EMG) magnitudes recorded from (residual) tibialis anterior (TA) and lateral gastrocnemius muscles (GAS), respectively. The six able-bodied and six transtibial amputees were recruited and asked to balance the inverted pendulum for ten 90-s trials. The results showed that the amputees were capable of controlling this unstable dynamic system with a proportional myoelectric control; however, they underperformed the able-bodied subjects, who maintained the pendulum closer to center (p = 0.041). Compared to the performance in the initial two trials, amputees improved the performance by significantly reducing the number of pendulum falls (p = 0.0329) and sway size (p = 0.048) in the final two trials. However, the amount of improvement varied across amputee subjects. Amputee subjects demonstrated different task adaptation strategies, including reduction of erroneous residual muscle contractions, development of an appropriate state-action (pendulum state-EMG activation) relationship for the task, and/or reduction of muscle control variability with the improved task performance efficiency (i.e., increased inactivity and sway minimization). The results suggest that after the training of transtibial amputees in coordinating antagonistic residual muscles in dynamic systems, it may be feasible to implement the proportional myoelectric control of the powered ankle prostheses in order to assist the postural control mechanisms, such as anticipatory and compensatory postural adjustments.}, number={7}, journal={IEEE TRANSACTIONS ON NEURAL SYSTEMS AND REHABILITATION ENGINEERING}, author={Fleming, Aaron and Huang, Stephanie and Huang, He}, year={2019}, month={Jul}, pages={1473–1482} }