Title:

Associate Professor

Office Information:

4212C EB3

Education:

PhD in Mechanical Engineering University of Florida, Gainesville 2010
MS in Mechanical Engineering University of Florida, Gainesville 2008
B.E. in Industrial engineering Thapar Institute of Engineering and Technology, Patiala, India, 2004

Email:

nsharm23@ncsu.edu

Lab Site:

http://www.pittsharmalab.org/

Research and Publications:

Research:

My research group is interested in deriving control methods that provide a safe and stable physical human-robot interaction for people with mobility disorders, undergoing neurorehabilitation. Specifically, my research group has designed assistive control methods for a lower-limb hybrid exoskeleton that combines functional electrical stimulation (FES) and a powered exoskeleton to enable people with complete paraplegia to stand and walk. Our long term goal is to derive control methods that enable people with paraplegia to achieve functional independence. To support this goal, we use variety of tools and methods from control theory that may include Robust Nonlinear Control, Model Predictive Control, Reinforcement Learning, and Neural Networks-based Adaptive Control. To provide stable interaction between the hybrid exoskeleton and a user, we are also investigating optimal surrogate signals derived from ultrasound imaging that inform residual muscle activity and the onset of FES-induced muscle fatigue. The lower-limb muscle activity or changes in muscle contractility are used to design a stable and controlled-assist from the exoskeleton. Other interests include control of time-delayed robotic systems such as during teleoperation, optimizing dosage of FES to minimize muscle fatigue, and control of an acoustic-powered microrobot.

Selected Publications:

  • Z. Sheng, N. Sharma, and K. Kim, “Quantitative Assessment of Changes in Muscle Contractility Due to Fatigue During NMES: An Ultrasound Imaging Approach,” IEEE Transactions on Biomedical Engineering,” accepted.
  • N. Alibeji, V. Molazadeh, F. Moore-Clingenpeel, and N. Sharma, “A Muscle Synergy Inspired Control Design to Coordinate Functional Electrical Stimulation and a Powered Exoskeleton,” IEEE Control Systems, 38 (6), pp. 35-60, 2018.
  • N. Kirsch, X. Bao, Brad E. Dicianno, and N. Sharma, “Model-based Dynamic Control Allocation in a Hybrid Neuroprosthesis,” IEEE Transactions on Neural Systems and Rehabilitation Engineering, vol. 26, no. 1, pp. 224-232,2018.
  • N.Sharma, C. M. Gregory, and W. E. Dixon, “ Predictor-based Compensation for Electromechanical Delay during Neuromuscular Electrical Stimulation,” IEEE Transactions on Neural Systems and Rehabilitation Engineering, vol.19, no.6, pp. 601-611, Dec. 2011.
  • N.Sharma, S. Bhasin, Q. Wang, and W. E. Dixon, “ Predictor-Based Control for an Uncertain Euler-Lagrange System with Input delay,” Automatica, vol. 47, no. 11, pp. 2332-2342,2011.
  • N. Sharma, K. Stegath, C. M.Gregory, and W. E. Dixon, “ Nonlinear Neuromuscular Electrical Stimulation Tracking Control of a Human Limb,” IEEE Transactions on Neural Systems and Rehabilitation Engineering, Vol 17, No. 6, pp. 576-584, 2009.