Real-time Neuromuscular Control of Exoskeletons

The purpose of this study is to develop a real-time controller for exoskeletons using neural information embedded in human musculature. This controller will consist of an online interface that anticipates human movement based on high-density electromyography (HD-EMG) recordings, and then translates it into functional assistance. This study will be carried out in both healthy participants and participants post-stroke. The researchers will develop an online algorithm (decoder) in currently existing exoskeletons that can extract hundreds of motor unit (MU) spiking activity out of HD-EMG recordings. The MU spiking activity is a train of action potentials coded by its timing of occurrence that gives access to a representative part of the neural code of human movement. The researchers will also develop a command encoder that can anticipate human intent (multi-joint position and force commands) from MU spiking activity to translate the neural information to movement. The researchers will integrate the decoder with the command encoder to showcase the real-time control of multiple joint lower-limb exoskeletons.

Inclusion Criteria for Healthy Participants: * Age from 18 to 80 years * No history of a brain and/or skull lesion * Normal hearing and vision, both can be corrected * Able to understand and give informed consent * No neurological disorders * Absence of pathology that could cause abnormal movements of extremities (e.g., * epilepsy, stroke, marked arthritis, chronic pain, musculoskeletal injuries) * Able to understand and speak English * Height between 3 foot 6 inches (1.1 meters) and 6 foot 9 inches (2.1 meters) Inclusion Criteria for Participants Post-stroke: * Age from 18 to 80 years * History of unilateral, supratentorial, ischemic or hemorrhage stroke greater than 6 months * Ability to walk independently on level ground, allowed to use assistive device or bracing * as needed * Medically stable * No planned surgeries, medical treatments or outpatient therapy during the study period * Normal hearing and vision, both can be corrected * Able to understand and give informed consent * Able to understand and speak English * Height between 3 foot 6 inches (1.1 meters) and 6 foot 9 inches (2.1 meters) Exclusion Criteria for Healthy Participants: * Weight over 220 lbs * Pregnancy (ruled out by pregnancy questionnaire) * Any neurological diagnoses or medications influencing brain function * History of significant head trauma (i.e., extended loss of consciousness, neurological * sequelae) * Known structural brain lesion * Significant other disease (heart disease, malignant tumors, mental disorders) * Non prescribed drug use (as reported by subject) * History of current substance abuse (exception: current nicotine use is allowed) * Recreational marijuana * Dementia; severe depression; or prior neurosurgical procedures * Failure to perform the behavioral or locomotor tasks * Prisoners Exclusion Criteria for Participants Post-Stroke: * Weight over 220 lbs * Pregnancy (ruled out by pregnancy questionnaire) * Botox (botulinum toxin) injection to lower limbs within the prior 3 months, or planned * injection during study period. * History of current substance abuse (exception: current nicotine use is allowed) * Reduced cognitive function * Severe aphasia * Prisoners * Co-existence of other neurological diseases (ex: (Parkinson's disease, traumatic brain * injury, multiple sclerosis, etc.) * Mixed or complex tremors * Severe hip, or knee arthritis * Osteoporosis (as reported by subject) * Medical (cardiac, renal, hepatic, oncological) or psychiatric disease that would * interfere with study procedures for HD-EMG