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Real-time Neuromuscular Control of Exoskeletons
Sponsor: Shirley Ryan AbilityLab
Summary
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.
Key Details
Gender
All
Age Range
18 Years - 80 Years
Study Type
INTERVENTIONAL
Enrollment
80
Start Date
2021-05-05
Completion Date
2025-12
Last Updated
2025-05-25
Healthy Volunteers
Yes
Conditions
Interventions
Isometric contractions
HD-EMG grids will be applied to the lower limb muscles of interest. Isometric contractions will consist of applying joint torque to reach a pre-defined torque level based on the subject's maximal voluntary contraction (i.e., 25%, 60%, 70%, 80%, 90%). The participant will control torque intensity by responding to a biofeedback displayed on a screen. The joint will be secured with non-compliant bands to prevent any movement of the participant. The order of the joints tested (i.e., dominant ankle, knee, or hip joint) will be randomized.
Isokinetic contractions
HD-EMG grids will be applied to the lower limb muscles of interest. Isometric contractions will consist of moving a joint to completing a set of contractions (10-20 contractions) at various velocities (i.e., 10 degrees per second, 30 degrees per second, 60 degrees per second). The joint will be secured with non-compliant bands to prevent any movement of the participant. The order of the joints tested (i.e., dominant ankle, knee, or hip joint) will be randomized.
Dynamic contractions
HD-EMG grids will be applied to the lower limb muscles of interest. Multi-joint tasks (i.e. walking, squatting, cycling) will be performed at a given frequency. A motion capture system will be used to record the joint angles and ground reaction forces simultaneously.
Isometric contraction with muscle fatigue
An identical experiment will be performed as stated in "Isometric contraction" with the addition of induced muscle fatigue by repeatedly maintaining 40% of muscle torque until failure to maintain a contraction for 5 seconds.
Multi-joint functional activities while wearing exoskeleton
Participants will be measured and fitted with the bilateral exoskeleton, and sufficient range of motion to used exoskeleton will be confirmed. HD-EMG grids will be applied to the lower limb muscles of interest. The participant will perform single-joint movements to calibrate the decoder parameters. The participant will then perform multi-joint activities (e.g., standing, squatting, walking overground or on a treadmill, cycling, or stair climbing) in a movement analysis laboratory
Clinical Assessments
Subjects may complete a 10 meter walk test (10MWT) overground or over a pressure-sensitive walkway, 6 minute walk test (6MWT), Berg Balance scale (BBS), and/or Functional Gait Assessment (FGA). They may also complete step ups or squats.
Locations (1)
Shirley Ryan AbilityLab
Chicago, Illinois, United States