Human-Machine System for the H2 Lower Limb Exoskeleton

Inclusion Criteria: * Sub-acute or chronic stroke i.e., interval of at least 3 months or interval of at least 6 months from stroke to time of enrollment, respectively; * Cognitive ability to assimilate and participate actively in the treatment protocol (Mini Mental State Examination score \> 24 points, out of a total 30 indicating normal cognitive ability); * Modified Rankin scale scores 2-4 (Mild-Moderate functional disability post-stroke); * Modified Ashworth Scale of Spasticity score \<= 2 (ranges from 0-4 with 4 reflecting maximum spasticity); * Have no skin integrity issues; * Sufficient passive range of motion at the hip (at least 90 deg flexion, 15-20 deg extension), knee (90 deg flexion, complete extension) and ankle (15 deg dorsiflexion, 15 deg plantarflexion); * Have no contraindications to standing or walking; able to stand with assistive device for at least 5 minutes, and able to walk with assistive device for 10 m. Exclusion Criteria: * Severe cognitive and/or visual deficit; * Hemineglect (determined based on medical record or initial clinical assessment); * Severe sensory deficit; * Joint contractures of any extremity that limits normal range of motion during ambulation with assistive devices; * Skin lesions that may hinder or prevent the application of exoskeleton; * Uncontrolled angina; * Severe chronic obstructive pulmonary disease; * Other medical contraindications; any medical co-morbidities that would prevent standard rehabilitation. Inclusion criteria for healthy, able-bodied participants: * Able to understand and sign the consent form * Age 18-75 years Exclusion criteria for healthy, able-bodied participants: \- History of neurological, neuromuscular or physical disability.