Active Ankle-Foot Orthotic

1. Active Ankle-Foot Orthotic Team P13001 Nathan Couper, ME Bob Day, ME Patrick Renahan, IE Patrick Streeter, ME Air Muscle Tethered This material is based upon work supported by the National Science Foundation under Award No. BES-0527358. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author and do not necessarily reflect the views of the National Science Foundation.

2. Agenda • Project Description • Problem Description • Assumptions and Project Scope • Customer Needs • Engineering Specifications • Design Process • Functional Decomposition • Morphological Design Process • Solution • Demonstration • Testing Results • Project Results • Future Work

3. Problem Description • Foot Drop • Caused by nerve damage in the lower leg or brain • Strokes, ALS, MS, Car Accidents, Other Trauma • Loss of muscle control prevents patient from dorsi-flexing the foot while walking, as well as extending the toes • AFOs are current solution • Generally rigid support that lifts the foot to a proper angle • Shortcomings of AFOs • Do not allow for smooth gait cycle • Inhibit plantar flexion • Descending stairs and ramps is very difficult without plantar flexion

4. Assumptions and Project Scope • Client maintains zero muscle control over dorsi-flexion, plantar-flexion, and toe extension • The system is designed to be used in a clinical setting • Tethered System • Client has the ability to use a dorsi-flex assist AFO • AFOs will continue to be custom made for each client • Control method for system should be adaptable to previously designed terrain sensing system

5. Customer Needs

6. Engineering Specifications

7. Agenda • Project Description • Problem Description • Assumptions and Project Scope • Customer Needs • Engineering Specifications • Design Process • Functional Decomposition • Morphological Design Process • Solution • Demonstration • Testing Results • Project Results • Future Work

8. Functional Decomposition

9. Functional Decomposition

10. Morphological Design Considerations

12. Solution: Passive Dorsi-Assist, Active Plantar-Assist Air muscle powers plantar flexion Elastomer passively causes dorsiflexion (dorsi-assist) Does not disturb positive attributes of dorsi-assist device Easier for clients to use than an air muscle that actuates in both dorsi- and plantarflexion

13. Testing Results • Air Muscle Fill Time • Used a high speed camera (120 fps) • Verified air muscle inflated fast enough for natural gait • Decibel Testing • Inflation and deflation of air muscle produced acceptable decibel levels

14. Testing Results • Lifetime Testing • All tested air muscles lasted significantly longer than required for specifications • No failure or fatigue was observed in testing of attachment points • Range of Motion • Found to be adjustable up to 64o when descending stairs • Average healthy person uses 48o when descending stairs

15. Project Results • Successfully combined an AFO and air muscle system to facilitate more natural movement in the ankle joint.

16. Future Work • Combine air muscle system with existing terrain sensing system • Human trials: test functionality of device on clients who have foot drop • Neuroplasticity: study effects of device from a rehabilitation standpoint rather than an aid

17. Demonstration

18. Questions