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- TIRES
- Priority Customer Needs
- Self cleaning tires
- Tires that can allow the user to reach home in case tires go flat
- Tires should be less expensive
- Tires should be non-marking
- Tires should be conductive
- More reliable (e.g. less likely to puncture)
- More durable - tires should have a typical life of at least one year or 1000 miles minimum
- Tires should be maintenance free (no need to add air, clean, etc.)
- Tires should enhance driving performance
- Tires should have low rolling resistance
- Tires should not "dry out" and crack
- Tires should provide good traction on all surfaces-sand, rugs, snow, smooth and rough surfaces etc.
- Tires should provide smooth and quiet ride on all surfaces and environments
- Tires should have seasonal adaptability i.e. tires should be able to perform equally well in all seasons like summer, winter etc.
- Manual wheelchair tires should provide good gripping in case user wants to use the tires directly to push the wheelchair instead of pushrim
- MEMS - Sensors in tires to let the user know when the tires are getting low. This should come at a low cost.
- State of Existing Technologies
- Polyurethane tires with sealed air tube inside do not require any maintenance. They have many desirable tire properties but don't have good traction and are slippery to grip. Thus they provide compromised performance.
- Tubeless inserts are heavy and difficult to install.
- Pneumatic tires have the highest performance but the poorest durability and reliability.
- Some manual wheelchair tires get dry on their sides with use. This creates blisters etc. on the hands of user who directly pushes on tires.
- Some manual wheelchair tires have too smooth side walls. Therefore user have hard time propelling such tires as their hands slip when they propel such tires directly.
- Mountain bikes manufacturers are working on self-shedding (self-cleaning) tire designs.
- MEMS technology is available for tire applications but is likely to have a very high cost ($6000).
- Electrically conductive tires are available but at a very high cost.
- Solid tires are maintenance free but do not provide adequate shock absorption. This leads to uncomfortable ride.
- Back and front wheel size affects rolling resistance. In case wheels are required to be replaced, any deviations of size of the new wheels from older wheels impacts the rolling resistance. This change in rolling resistance is uncomfortable and dangerous for the wheelchair user.
- Ideal Technology
- More durable tires, which have at least a minimum life, span of 1000 miles or a year.
- Tires should have low rolling resistance
- Tires should have high traction on all surfaces (possibly through "intelligent" adaptation
of tire properties or configuration).
- Tires should be non-marking on all surfaces.
- Tires should be conductive so as to prelude the buildup of static charge.
- Tires should run smoothly and quietly.
- Tires should have low turning resistance.
- Tires should not dry out on their sides.
- Manual wheelchair tires should have side-walls with high coefficient of friction so as to provide good gripping.
- Tires should have resilience (conformability) comparable to pneumatic tires.
- Tires should be self-cleaning.
- Tires should have all season adaptability (perform well in all seasons and environments).
- Tires should be completely maintenance free.
- Tires should have "run flat" capability i.e. tires should
be capable of traveling over a certain minimum distance in case
they go flat so that the user is not left stranded in some unsafe
place.
- Tires and wheels should be of some standard size (probably size of bicycle tires). This will improve tire availability and serviceability. In addition, tires will be produced more economically.
- Tires should have the performance characteristics of a pneumatic tire but the durability characteristics of a solid tire.
- Tires should provide good shock absorption.
- Barriers to Realization of Ideal Technology
- Small market for the wheelchair tires prevents manufacturer from investing their money into research in this field. This disadvantage may be overcome for manual wheelchair tires by leveraging bicycle tire market.
- Current reimbursement policy also hinders development in this area.
Industry in U.S. is governed by "K" codes.
- There is resistance to change on the part of manufacturer.
- Consumers are not vocal about their wheelchairs, cost, things that break etc.
- Some wheelchair users use parking brakes to slow down the chair. This leads to more wear of the tires. Users should be educated about the efficient use of tires.
- Tires and wheels need to be aligned properly. Any misalignment increases the tire wear, which reduces the life cycle of the tire.
- FRAMES
- Priority Customer Needs
- Need lighter weight, low cost, adjustable frames. Such frames would serve the broad manual wheelchair market.
- Frames should be shock absorbing.
- Need modular wheel chair frame- a chair that can grow.
- Clinicians should be able to make custom changes to the chair frame using some software.
- Wheelchair frames should be crashworthy.
- Tie down points needs to be standardized. Integration of tie down points or other docking interfaces to secure wheel chair in transport.
- Forward/backward adjustable axle are required even in low cost manual wheelchair
- Need for improved joining methods for dissimilar metals
- Accessory items on the wheelchair should be ergonomically located. Frame should probably be provided with standard mount points so that it may be easy to reach these accessory items.
- Wheelchair frames should be designed such that it can easily accommodate new component. (e.g. mount points should be provided at suitable locations, frame tubing should be accessible)
- Mountings and mount points for the seat and back should be strong
- State of Existing Technologies
- The commodity wheelchair (K-1), being price sensitive, uses no advanced materials.
- K-5 chairs use some advanced materials but truly advanced materials are used primarily in high end wheelchair market.
- Most of the wheelchairs are need to be customized at the point of sales to accommodate user specific needs.
- Manufactures claim to have access to high performance materials (e.g. titanium, chrome-molybdenum etc.) and to advanced composites (e.g. kevlar, carbon fibers etc.).
- Kevlar and carbon reinforced products are expensive and difficult to manufacture. These products are therefore restricted to niche market.
- Ideal Technology
- Manual wheelchair frames should be of less weight and low cost.
- Frames should be shock absorbing.
- Frames should be modular.
- Frames should be crashworthy.
- Frames should have standard tie down points so as to secure the wheelchair in transport.
- Forward/backward adjustable axle should be provided even in low cost manual wheelchair.
- Frames should have standard mount points, which are located such that the accessory items can be reached ergonomically.
- Frames should easily accommodate new component/accessory item.
- Frames should have strong mounting and mount points for the seat and back.
- Method for joining dissimilar metals should be more efficient.
- Barriers to Realizing Ideal Technology
- Current "K" classification is based on chair design developed
15-20 years back. There is need for coordinated efforts to change
reimbursement policy. Current policy and HCFA do not foster innovation,
consumer exploration of new products/designs.
- Changing to new production processes and equipment is very costly.
- The market is very price sensitive, which means that better technology, has to be made available at either no increase in cost or a very moderate increase in cost.
- There are technologies (e.g. for bonding dissimilar materials, advanced materials etc.), that exist in federal labs but would be very costly to incorporate into wheelchair products at present.
Other Needs and Suggestions
- Armrest material should not "dry out". User can get hurt when their hands rub on a "dry out" armrest.
- Scooter armrest needs to be more durable. Often the scooter armrest catches on the doors etc and the material of the armrest tears away.
- There is a need for armrest materials that will not stretch and crack. Such material can also be used backrest and the seat.
- There is a need for standard tie down point design on scooter. Scooters are frequently damaged due to the lack or bad design of tie down points.
- Public transportation workers don't know how to help secure people in wheelchair or scooter.
- Caster rotation catches feet and causes injury
- Smaller casters provide good maneuverability but there performance is not good on rough terrain (gravel)
- Wheelchair should be designed such that a person in wheelchair is capable of picking up something from the floor.
- Skirt Guards should probably be inserted into the wheelchair design
- Footrest needs to be more adjustable to compensate for leg length.
- "Add on" become cost and maintenance issues. Efforts should be directed towards making anything build onto the chair instead of an "Add on".
- To increase the stability of the chair, sensor technology can probably be employed. Sensors need to perform function such as sense the speed, turning radius, weight of the person in chair etc. This information can than be used to adjust the speed automatically, detect curve and act accordingly.
- There is a need for quicker and easier fastening
- There is a need for stronger fastening
- Seating material should not interfere with transfer
- Probably wheelchair users should have the option of leasing the chair.
- Policy research is needed to bridge gaps in reimbursement costs.
- Technologies in parallel industries which have the potential wheelchair application needs to be identified and transferred to the wheelchair industry.
- More active R&D collaboration between industry and fed labs
is needed.
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