Project DefinitionFoot drop is a neurological disorder which impairs the ability of an individual to dorsiflex the foot (i.e., point the toe upward). This condition is a common side effect of a stroke, ALS, Multiple Sclerosis, or a peroneal nerve injury. Patients who experience Foot Drop utilize an assistive device known as an ankle-foot orthotic (AFO) which provides a stable and comfortable support for their foot and ankle and thus mitigates the condition effects. Current AFO’s are bulky, rigid, and disrupt the user’s natural gait by providing assistance at all times, regardless of need. An active AFO will provide users with assistance only during appropriate times in the gait cycle.
The specific goal of our team is to incorporate previous work done, including using a McKibben muscle and a terrain sensing system into an untethered AFO. It also should have an aesthetically pleasing flexible exoskeleton made from allergy conscious materials which comfortably fits into a user’s existing footwear. The exoskeleton need to be integrated with the actuation device, sensing system, and microcontroller. The AFO must also must be capable of applying torque to and rotating the user’s foot and should be designed to endure an entire day use untethered. The sensors and microcontroller system should incorporate the existing terrain sensing system as well as implementing more suitable heel strike sensing. The resulting design and prototype must follow the safety standards set forth by the Institutional Review Board as well as the ASME Boiler and Pressure Vessel Code.
- Users of AFOs
- Clients’ doctors
- Therapists, aids
- Family and care takers
- The customer: Dr. Elizabeth DeBartolo
- Future investors in the final product
- The members of this team
- RIT Senior Design Program
General Use Scenario
Daily Use Scenarios
Customer RequirementsReturn To Top
|Interview Date||Interview Subject||Interview Questions||Interview Notes|
|August 28, 2014||Dan Higgins||August 28 Questions||August 28 Notes|
|September 2, 2014||Dr. Elizabeth DeBartolo||September 2 Questions||September 2 Notes|
|September 4, 2014||Dr. Kathleen Lamkin-Kennard||September 4 Questions||September 4 Notes|
House of Quality
Critical Design Challenges
- Creating a closed system with a day’s worth of pressurized air.
- Creating enough force to pull the foot up while not adding to the shoe size.
- Minimizing the gait and terrain monitoring system so that it can fit on the leg.
- Laying the muscles on a soft material.
- Keeping the weight low.
- More reliable source for heel strike sensing
- The system must use untethered McKibben muscles as the means of foot actuation.
- The exoskeleton skeleton must be made out of a flexible, washable material. The material must also be hypoallergenic and non-abrasive without sharp protrusions.
- Use existing IR-based terrain sensing system. Heelstrike sensing may be adapted to a more suitable sensor.
- Device must accommodate a general range of population (5th percentile females to 95th percentile males)
- User must be able to wear his/her regular shoes while wearing device
- The device must follow safety standards as applicable including, but not limited to: Institutional Review Board (IRB) and ASME Boiler and Pressure Vessel Code.
- The AFO should also resist foot slap.
Concerns and RisksTeam Dynamics • Creating and meeting deadlines • Team’s response to first serious problem or crisis • Team overdesigns the product creating an unfeasible design (e.g. addition of unnecessary functionality) and thus loses focus on the things that are most important
AFO Functionality • Too soft and thus not strong enough to provide the necessary force • AFO doesn't allow usage over obstacles • Creating an AFO that can be put on/taken off with only 2 people, including the patient • Inability to display to an external monitor • Muscles on the front of the leg may sacrifice working life
AFO Fit • Unable to fit orthotic into the user's normal shoe • Accommodation of a wide range of foot sizes • AFO slipping down the leg
AFO Comfort • Overheating of leg • AFO heavier than desired • Ability to provide necessary rigidness without sacrificing comfort
Compressed Air • The amount of air that the prototype will be able to hold will not be enough to last an entire day of use • High level of noise
McKibben Muscle(s) • Unable to attach McKibben muscle to an soft exoskeleton • Ability of air muscles, attached to front of AFO, to provide enough force to raise foot • Range of motion that can be produced by muscle
PCB Board • Not cost effective • Not timely to build • Too large
Arduino Board • Not able to drive the muscles
Battery • Ability to find a light weight and low cost battery that can provide an entire day’s use
Safety • Ensuring AFO does not hurt the patient during downtime • Reliability and safety of manual switch, especially for driving and stopping (and ease of use) • Client gets injured and needs to take off AFO • AFO rusts and corrodes • AFO breaks during usage • Client experiences circulation cutoff • Too many wires hanging off of user
Terrain Sensing System • Unable to identify stairs • Sensors spike • Inability to decrease the size of system • Terrain sensing start up and stopping • Terrain prediction not sensed • Infrared sensor functionality
Heal Strike • Finding a more reliable source for detecting heal strike. • Is the current method of measuring foot-strike the best method and the method we want to use?
Research and BenchmarkingReturn To Top
- Patterson Medical - Foot-Up Shoeless
- Bio-inspired Active Soft Orthotic Device for Ankle Foot Pathologies
- P13001 - Active Ankle-Foot Orthotic: Tethered Air Muscle
- P13002 - Ankle-Foot Orthotic Un-Tethered, Mechanical
- P14029 - Robotic Fish Powered by Hydraulic McKibben Muscles
Problem Definition Review
|Home||Planning & Execution||Problem Definition||Systems Design||Subsystems Design||Detailed Design||Gate Review|
|Build Preparation||Build & Test||Integrate & Assemble||System Validation||System Verification||Final Review|