PlayGait: A Dynamic Exoskeleton

Inclusion Criteria: * Age 3 - 4 years (at time of informed consent) * Hemiplegic cerebral palsy * If child uses an ankle-foot orthosis (AFO), parent/caregiver is willing to have the child stop wearing their prescribed AFO during data collections (lab sessions and two 7-day periods at home) * Ability to walk at least 10 meters without the use of assistive devices or AFOs * Ability to walk at least 1 minute without the use of assistive devices or AFOs * Stiff knee gait - less than normal knee flexion during swing phase * Hip flexion passive range of motion contracture less than 20 degrees * Gross Motor Function Classification System (GMFCS) Levels I-II * Modified Ashworth Scale (MAS) \<=2 for the gastrocnemius soleus, rectus femoris, and hamstrings * Family has resources to attend all study sessions (transportation, schedule) * Ability to speak and understand in English Exclusion Criteria: * Orthopedic surgery in the last year * Foster children or wards of the state * Use wheelchair or stroller mobility as their primary method of independent mobility * Severe visual impairment such that the visual impairment itself functionally limits mobility * Phenol or Botox injections to the legs in the last 3 months * Uncontrolled seizure disorder, defined as any seizure in the last 3 months that influenced mobility skills and function (seizures which did not affect mobility are acceptable) * Lower limb fracture in the last 3 months * Planned surgery or changes to movement disorder medication during the study period * Inability to understand directions sufficiently to complete the study assessments * Cognitive, behavioral, or any other issues that may not allow for effective study participation * Unwilling to complete the study protocol