Our primary research focus is on the design of nonlinear and adaptive control algorithms for functional electrical stimulation (FES) and rehabilitation robots.  Currently, we are interested in designing control algorithms that coordinate FES and a powered exoskeleton that assist walking and standing functions in persons with spinal cord injury.  Integrating FES and an exoskeleton has many technical and therapeutic benefits. FES induces artificial but active muscle contractions contributing to muscle health and reanimation of paralyzed muscles. However, FES-induced muscle fatigue hinders its clinical implementation. We are designing control algorithms that enable a powered exoskeleton to work in tandem with FES and thus compensate for the muscle fatigue. The control design problem is challenging due to the disparate dynamics of FES and the exoskeleton, need to monitor the state of the muscle, and residual volitional effort of the user, if present. We are also working to include novel muscle state sensing modalities such as ultrasound imaging and surface electromyography. Our research is multidisciplinary and therefore we collaborate with clinicians in physical medicine and rehabilitation, physical and occupational therapists, and faculty specializing in ultrasound imaging.

Research Highlights



  • Dr. Sharma (PI) and Dr. Sung Kwon Cho (Co-PI @Pitt) win NSF Grant: Integrated Swimming Microrobots for Intravascular Neuromodulation
  • Dr. Sharma invited to 2022 EU-US Frontiers of Engineering Symposium in Slovenia

Recent Publications

  • Z. Sun, A. Iyer, K. Lambeth, C. Cleveland, N. Sharma, “Knee Extension Tracking and Fatigue Regulation Results from a Robust MPC approach in a Hybrid Exoskeleton, Control Engineering Practice, accepted
  • N., Sharma, X. Xue, A. Iyer, X. Jiang, D. Roque, “Towards Ultrasound Imaging-based Closed-loop Peripheral Nerve Stimulation for Tremor Suppression,” Current Opinion in Biomedical Engineering. 2023 Jun 24:100484.
  • Q. Zhang, K. Lambeth, Z. Sun,  A. Dodson, X. Bao, N. Sharma, “Evaluation of a Fused Sonomyography and Electromyography-based Control on a Cable-Driven Ankle Exoskeleton,” IEEE Transactions on Robotics, accepted.