Page 21 - Mobility Management, July 2019

Ethos: An Answer to Bad Vibrations
To maintain balance, conventional wisdom says that for every gain, there must be a loss.
But the new Ethos ultralightweight wheelchair from Ki Mobility challenges that notion in significant ways.
The Cost of Vibration
Many of today’s K0005 chairs have minimalist designs and use advanced materials such as aerospace-quality aluminum, titanium or carbon fiber.
Thanks to these incredibly lightweight and highly adjustable chairs, consumers can stay active for longer periods. But those longer durations also expose them to more vibration as they roll through parking lots, go over sidewalks, and transition from flooring to carpet or tile.
Alan Ludovici, Senior Design Engineer at Ki Mobility, the designer of the Ethos and a longtime K0005 user, said pain and fatigue are among the effects that vibration can have on wheelchair users.
“If you are on a relatively fine surface but you get a lot of harmonics going through the chair, that’s when it hurts,” he said. He added that vibration also can trigger spasms and spasticity.
“There are days that I’m just wiped out from the pain I’m in all day,” Ludovici said. “\[Vibration\] is a normal part of being in a wheelchair, period.”
Ethos keeps in mind that a wheelchair is only successful as long as its consumer can continue to use it. Jacki Rettler, Product Manager for Manual Mobility, said, “Vibration is a part of every day. \[Users\] can’t choose
not to roll across the parking lot. That’s why the vibra- tion-damping aspect of the Ethos is so genius.”
Separating the Seat & Base Frames
Ethos attacks the vibration problem from multiple angles. First, the seat frame and the base frame on the Ethos
are separated, and the caster wing isn’t attached to the front of the chair. “Alan isolated the seat frame from the base frame,” Rettler said. “In doing so, the traditional caster wing that acts as a conduit to a lot of the vibration that the user feels was cut off.” (See it in action at https:// www.kimobility.com/ethos/.)
Ethos also addresses residual vibration via ISO TECH, a patent-pending technology that acts as a second shield
for the rider. “There are towers that extend out from the base frame that connect to the seat frame, and inside those towers are polymers,” Rettler said. “They are avail- able in different densities or durometers. No matter what density you use, you always get the vibration-damping benefits of the chair design through the seat frame isola- tion, and then these secondary shields, the polymers. They absorb any of the residual vibrations that traveled through from the base frame up through the towers.”
K0005 Performance Requirements
While reducing everyday vibration is significant, Ethos must also fulfill other K0005 requirements, such as a high level of adjustability, plus an ultralight weight that facili- tates propulsion and transporting the chair.
“I didn’t want to lose any energy going to the wheels or efficiency in pushing,” Ludovici explained. “There are other ways to dampen vibration. You can have soft casters on the front; you can have soft wheels on the rear. But that slows you down. You use a lot of energy, and you don’t roll as far. With the Ethos, you’re able to use performance tires front and rear and get the efficiency of the pushing, but the way the seat frame is somewhat separated from the base frame with the elastomers, the seat then becomes part of your body. It’s the difference between riding on top of something and being \[part\] of something.”
Rettler said Ethos’s design also provides optimal weight distribution: “The benefit of integrating the caster into
the base frame and not attaching it to the seat frame is now you have this ability to manage the wheelbase. That caster telescopes in and out of that base frame, so you get about 4" of adjustability of that front caster. No other rigid frame does that.
“The result is that you can optimize the placement of the wheel, you can optimize the chair setup for perfor- mance or for more stability, but you’re not sacrificing one for the other anymore. You can also balance the weight of that rider across the wheelbase in such a way that no other chair allows you to do.”
Ludovici agreed: “You can get a fairly aggressive center of gravity and still be able to push the casters way forward for stability. I’ve always had a pretty on-the-edge center of gravity, but if I lean forward to pick something
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