When wheelchair users in developing countries face rocky slopes, steep hills and muddy paths, their hospital-grade wheelchairs won't cut it. But the all-terrain wheelchairs available in the United States are much too expensive for the developing world market. That problem inspired Amos Winter, an assistant professor in the Department of Mechanical Engineering at the Massachusetts Institute of Technology, to develop the Leveraged Freedom Chair. (Photo below.)
I spoke with Winter this month about how he found inspiration for his design in a mountain bike, how constraints aided his innovation and his efforts to translate the technology for the developed world. Below are excerpts from our interview.
What inspired you to build a cheap, all-terrain wheelchair?
It started in the summer of 2005. My girlfriend at the time was living in Tanzania doing a fellowship and I was finishing up my master's. I wanted to spend the summer with her doing something technology related. Through MIT, I got hooked up with a wheelchair organization in San Francisco called Whirlwind Wheelchair International. They design wheelchairs for developing countries. I was also connected with an organization in Tanzania that teaches people to build wheelchairs and set up their own workshops. Both of those groups wanted to have an assessment done of the current state of wheelchair technology in Tanzania to see how well it was meeting people's needs.
I spent a summer talking to wheelchair users and manufacturers and disability groups. What stood out after that experience was that the currently available products on the market didn't meet the mobility needs of people who need wheelchairs, particularly in rural areas. What's commonly available in the developing world are either Western style wheelchairs, usually the simple type you find in a hospital or airport. It's quite difficult to propel yourself on rough ground. To go a mile from your home to your job is really arduous. The other products that are more prevalent in the developing world are hand-powered tricycles. You ride these like a bike, but pedal with your arms. There's a hand crank in front of you that drives the chain. These tricycles are more prevalent because they enable a person to travel quite fast and efficiently on smooth ground, so they're great in city areas. The problem is they're not geared well for rural areas and rough ground. It's arduous to go up steep hills or through mud or sand. They're also too big to use indoors, so you have to crawl on the ground.
I looked at this technology space and saw there was no product that could both enable users to travel fast and efficiently on a variety of terrains and be usable enough indoors. I started thinking about how we could design a product like this.
What attributes would this wheelchair need to have to be useful for people in rural areas of developing countries?
We wanted something like a mountain bike for your arms that would enable you to travel fast and efficiently on smooth terrain, but would give you enough mechanical advantage to be able to go over very rough terrain, like mud, sand or hills. It should also be small enough to fit through doorways and under a table and into a bathroom. With a wheelchair, you're spending most of your time just sitting in it.
We needed mountain bike levels of performance without mountain bike costs and complexity. A mountain bike has a multiple-gear drive train where you can shift the chain to get different levels of mechanical advantage. You can buy multi-stage gear trains in developing countries, but they're uncommon, very expensive and poorly made. If you had one of these systems and it broke down, it might be tough to repair. We needed this large range of mechanical advantage, but on a simple, easy-to-repair and low-cost system.
In your TED Talk, you described how the constraints of the project -- must be under $200, must travel up to five kilometers a day on varied terrain, must be locally repairable -- led to a fundamentally new product. Do you think we should put more constraints on our projects when trying to innovate?
Absolutely. It was certainly the case here. I looked at the existing wheelchair technology space in terms of cost versus performance. On one side of the scale, you have wheelchairs made for developing countries. They cost anywhere from $75 to $150 and they're a hospital-style wheelchair. They have wheels. They enable a person to sit. But they don't stand up to the rigor in a rural area. They're not made of easily replaceable parts. They don't provide good posture support. That's the low end, where you reduce cost by reducing performance. At the upper end of the scale, you have wheelchairs that go on rough terrain very well, that are available in the U.S. and Europe. They cost anywhere between $4,500 and $6,500. That's way out of the price range. They're quite complex and you could never repair them in this context.
We needed a device that had the off-road performance of the high-end wheelchairs, but at a price point close to the developing world wheelchairs. We wanted to have a wheelchair that existing donation organizations and funders could afford and not have to justify much higher costs. The price point had to be about $200. Realizing that we couldn't just take existing wheelchair technology and adapt it pushed us into a new innovation space. We needed to innovate on a technology that's been relatively unchanged for 140 years. As far as a design pedagogy standpoint, this is powerful. You look at emerging markets. You look at developing countries. You have technical problems that need a solution and you can't simply take a Western technology, reduce features to reduce price and think it's going to work perfectly. There's a whole study of this coming up now. It's reverse innovation. Because of the constraints we faced, we had to innovate. The technology is globally relevant.
As you set out to design this, you started with the idea of a mountain bike and ended up at the simple solution of levers. Talk about the design process.
The big innovation in our chairs is the lever system. After I spent that first summer in Tanzania, I realized we needed something like a mountain bike, but couldn't use a mountain bike. I thought through many different ideas. It took about a year and a half to come to a solution. Finally, I came to this lever solution. With the lever solution, the person provides the complex mechanical motions to change mechanical advantage, rather than the machine. In a mountain bike, it's the machine that's shifting the chain from gear to gear. But in our system, it's the person shifting their hands up and down the levers. The machine could be a very simple assembly of single-speed bicycle parts that you can get anywhere. That was an important insight.
This is such a beautiful illustration of the well-meaning academic that doesn't understand all the components of making a viable product. We put the lever idea on a wheelchair and the first embodiment was brought to Tanzania, Kenya and Vietnam. Our partners said, 'This thing is awful!' It was heavy, awkward and dangerous. Everything about it was horrible. That feedback from the stakeholders was critically important. It brought us back to the drawing board. We started this iteration cycle of working very closely with stakeholders, both people who tried the chair and organizations. Through the iterations, the chair got smaller, narrower, lighter, more stable. We moved the position of the levers to change how you could affect mechanical advantage. Everything got better and better. As we went through the iterations, the changes between each iteration got smaller. The feedback indicated we were getting closer to a viable product.
At our last trial in India, people were much faster, much more efficient than with a normal wheelchair. They didn't have much input about what to change. The 11 people in the trial had been using a regular wheelchair and 10 of them switched to our model. With the regular wheelchair, none of them could leave their house without the help of a family member. With our wheelchair, they traveled an average of 2.7 kilometers a day. Four of those people got a job as a result. That's really powerful to see.
Our wheelchair was about 78 percent faster than a conventional wheelchair going on a dirt road. It was 41 percent more efficient as far as how fast you could go based on the metabolic effort. The chair was also able to put out 51 percent more torque at the wheel than a regular wheelchair.
How many wheelchairs are out in the world now? And where are they?
We've delivered more than 100. We're just now getting to the point where we'll take orders from anybody. We did a pilot distribution in India with 100 chairs. There's another 200 that will happen with that. There's a pilot in Haiti with 20 chairs. The plan is to deliver 1,200 there in the next few years. We get inquiries everyday from organizations that want this. We're tooled up to produce 500 a month, so we'll be able to scale up quickly.
And you're also planning a model for the developed world?
We're working on a model right now. We're figuring out what we have to adapt in the technology to make it desirable in the rich world. The fundamental mechanical behavior of the wheelchair is great. But there are things like weight and aesthetics and transportability in a car that deserve more consideration in the rich world. Part of my research is to articulate this design process and adapt it into a rich market. We're planning to do focus groups and short field trials with the developing world wheelchair and the rich world market.
What’s next for you and this project?
I'm a professor and the reward and value structure of academia is based on producing knowledge, not products. I came to the point where I realized that I wanted to commercialize this, but if I spend a lot of time and effort doing that, it could be damaging to my academic career. We set up a company called Global Research Innovation and Technology (GRIT). It's doing all the business activities to get this product to market that aren't academic in nature, but are very important. I'm still involved with GRIT, but I don't run it. Two of my former students are running it. This company gives me a great resource to take technologies from my lab to hand them over to get ready to be commercialized. We're developing a low-cost prosthetic knee right now that provides a higher level of stability on rough terrain. The target is to make a $100 knee that performs like a $10,000 knee in the U.S. That's an example of a technology that would be great to commercialize through GRIT.
Photo, top: Amos Winter
Photo, bottom: Jagdish, a paraplegic patient who participated in the October 2011 Leveraged Freedom Chair trial outside Jaipur, India