Enhancing Voluntary Motion in Broad Patient Populations With Modular Powered Orthoses

The overall goal of this project is to develop modular, lower-limb, powered orthoses that fit to user-specific weakened joints and control force/torque in a manner that enhances voluntary motion in broad patient populations. Conventional orthoses tend to immobilize joints, and emerging powered orthoses constrain voluntary motion by using highly geared electric motors and/or control methods that force the user to follow a specific gait pattern. Consequently, these devices have not seen widespread success across populations with weakened voluntary control due to advanced age, musculoskeletal disorders, etc. These heterogeneous populations require partial, not full, assistance of user-specific muscle groups during daily activities. However, there is a fundamental gap in knowledge about how to design and control powered orthoses to assist the user without constraining their motion. The central hypothesis of this project is that high-torque, low-inertia motor systems controlled with energetic objectives will enable modular powered orthoses to partially assist the joints. High-torque electric motors combined with minimal transmissions can be freely rotated (i.e., backdriven) by human joints, allowing the use of an emerging torque control method called energy shaping to reduce the perceived weight/inertia of the body during any motion. By mounting these modular actuators to commercial orthoses, this technology will be easily prescribed/configured by clinicians. This project aims to establish feasibility of assisting different populations with modular powered orthoses. The investigators hypothesize that assisting lower-limb musculature with modular powered orthoses will improve 1) lifting/lowering posture in able-bodied subjects and 2) functional outcomes in elderly subjects.

Inclusion criteria

for able-bodied, young participants will be:

• Aged between 18 to 65 years
• Weigh less than 250 lbs due to limitations in the design of the orthoses
• Ability to lift and lower a 10 kg weight using the neutral-spine squat technique for 10 repetitions

Exclusion criteria

for able-bodied, young adult participants will be:

• Pregnant (self-report)
• Any significant neuromuscular or musculoskeletal disorder that would interfere with the study
• Prior history of chronic lower-back pain
• Unable to walk for 20 minutes
• History of any cardiovascular, vestibular, or visual diseases and/or impairments that may interfere with the study
• Cognitive deficits that would impair their ability to give informed consent or impair their ability to follow simple instructions during the experiments. Cognitive deficits will be determined by a Mini-Mental State Examination (MMSE) score of <22.
• Adults with a known allergy to medical grade tape

Inclusion criteria

for elderly participants will be:

• Aged between 65 to 85 years
• Weigh less than 250 lbs due to limitations in the design of the orthoses
• Ability to walk 6 minutes without assistance from a person (may use walking aid)

Exclusion criteria

for elderly participants will be:

• Pregnant (self-report)
• Significant pain due to arthritis or other joint problems that would limit their ability to walk
• Any recent lower-extremity fracture (within 3 months)
• Significant neurological (e.g., stroke), orthopedic, or cardiovascular disorder that may affect the ability to walk
• Advised by a physician not to walk or exercise
• Uncontrolled hypertension or diabetes
• Cognitive deficits or visual impairment that would impair their ability to give informed consent or impair their ability to follow simple instructions during the experiments. Cognitive deficits will be determined by a Mini-Mental State Examination (MMSE) score of <22.
• Adults with a known allergy to medical grade tape