The Story of a Wheelchair
Two senior engineering design teams at Dordt University are busy upgrading a pediatric wheelchair that’s already having a global impact.
Hope Haven, a life skills ministry program located in Rock Valley, Iowa, has distributed more than 20,000 wheelchairs to disabled children worldwide.
By working with eight Dordt engineering majors on two separate changes to the chair, Hope Haven expects to better meet the needs of children who otherwise wouldn’t be able to use the chair. The organization also hopes to make it easier to replace parts from afar.
This isn’t the first time the pediatric wheelchair has been part of a Dordt engineering senior design project. The current wheelchair design was born in the engineering labs at Dordt College nearly 20 years ago; it’s now back to be improved by a new group of Dordt engineering students.
Designing like it’s 1999
The story began in 1999 when Hope Haven approached Dordt’s engineering faculty with a need: Would senior engineering majors be interested in designing a pediatric wheelchair?
Hope Haven already had an army of volunteers who refurbished used wheelchairs to send to people in need, but the chairs were almost all adult-sized. Child-sized wheelchairs were more difficult to come by—and more expensive.
Hope Haven was looking for a pediatric wheelchair that could be assembled and shipped around the world for less than $200 per chair at that time.
“Their idea was that, with some donated spare parts, recycled plastics, and surplus materials from local contractors, they could put a simple wheelchair together,” recalls Dr. Nolan Van Gaalen, an engineering professor.
Back in 1999, senior engineering design was worth one credit hour and only one component of a larger engineering lab—not the four-credit hour, two-semester venture that senior design projects are today. Still, Van Gaalen and his fellow engineering faculty members believed their students would have enough time to design a wheelchair.
They connected Hope Haven with Mark Hubers (’99), a senior from Rock Valley. He and his roommates Trevor Mentink (’99), Paul Taatjes (’99), and Micah Vardeman (’99)—all mechanical engineering majors—decided to give the project a shot.
Hope Haven provided some design criteria. The chair needed to be constructed with tubing and blocks. It had to be safe, adaptable, durable, and easy to repair. It also had to be cost-effective; in 1999, a typical wheelchair built with purchased materials cost about $335, whereas Hope Haven and the Dordt students wanted to spend closer to $14 using donated material.
Hubers, Mentink, Taatjes, and Vardeman spent most of their time prototyping. Hubers recalls wandering around a warehouse in Rock Valley, trying to find the best use for recycled plastic 2x4s, refurbished wheels, and donated metal tubing. They searched out wheels for their design. They cut the length of the pipe and the plastic 2x4s as joints for the parts that needed to fit together.
“We would put together prototype wheelchairs and wheel them around North Hall, giving them a spin,” says Hubers.
And, when a prototype failed, they’d build another—learning something new with every design they tested.
Eventually, the four students compiled a 21-page report, complete with design criteria, strength analysis, wheelchair fabrication and documentation, and part drawings. They presented their findings to the engineering faculty and to Hope Haven. The rest is history.
At the time, Hubers and his roommates had no idea of the impact their initial wheelchair design would have.
“We were just seniors looking to graduate,” says Hubers. “We knew that the wheelchair design had the potential to affect many lives, but I for one didn’t think it would go to production.”
Since 1999, more than 20,000 wheelchairs have been built and shipped internationally to countries such as Vietnam, Romania, and Guatemala. Word spread to doctors, missionaries, and volunteers around the world that Hope Haven had a simple, cost-effective pediatric wheelchair design. Mark Siemonsma, director of development at Hope Haven, says families have walked 150 miles or more to receive a pediatric wheelchair.
“When a child with a disability gets a wheelchair, they and their loved ones gain freedom,” he says. “They don’t need to be confined to a room or depend upon their caretaker for mobility. The Dordt engineering students did that for us; they helped us to achieve our goals. We’re so thankful.”
Creating A Mechanical Tilt
Two years ago, Hope Haven staff again reached out to Dordt’s engineering faculty. The original wheelchair design worked well, but they thought some improvements could be made—a tilt mechanism, a better footrest, and a full computer-aided design (CAD) model of the chair.
Siemonsma talked with Ben Saarloos (’99), Dordt’s lab systems engineer, and Dr. Ethan Brue (’92), an engineering professor, about including these updates as a senior design project. Of the 63 ideas on his list of possible projects, Saarloos recognized that this one would fill an important need, had a clear champion in Hope Haven, and had a well-defined scope.
When it came time for the engineering majors to select their senior projects, eight students picked the pediatric wheelchair as their first choice—more than was needed. Rather than turning students away, Saarloos split the project into two. A group of three students would design the mechanical tilt, and a group of five students would create CAD drawings and design a moveable footrest.
Mykaela Ptacek, Eber White, and Levi Smith comprise the mechanical tilt team, meeting every Thursday afternoon to work on their project. During the fall semester, they spent hours in a conference room, examining a pediatric wheelchair prototype and sketching drawings. During the spring semester, they are spending more time in the 3-D printing lab and the engineering high bay, building prototypes and testing their designs. Ptacek is the team’s project manager, ensuring that they set goals, meet deadlines, and respond quickly to Hope Haven’s questions. The team meets weekly with Saarloos, their project mentor, to ask questions and review their progress.
Ptacek says she was drawn to the wheelchair project because she wanted to have a physical product to show at the end of the spring semester—something to follow from design to prototype. She found it an exciting challenge to produce a mechanical tilt on a tight budget, too.
“Ultimately, the pediatric wheelchairs are donor-funded, so producing a less expensive chair means it’s more likely that people will want to fund them,” explains Smith.
A primary draw of the project for each member of the team was its missional impact. Siemonsma says about 50 percent of the children Hope Haven encounters require the tilt mechanism to use a wheelchair—these are primarily children with severe cases of cerebral palsy and spina bifida.
“The original pediatric wheelchair design only helps the less disabled, because the children who have a more severe disability require too specific of a product,” Smith says. “Hope Haven will go into a region and help as many children as they can, but there’s a certain number of children that they have to leave behind. It breaks the volunteers’ hearts.”
The tilt mechanism will help some of those severely disabled children to sit upright and rest their muscles.
So, how did the team go about choosing a cost-effective, durable design that meets the needs of disabled children? With Saarloos’ help, the students put together a design matrix that examined categories such as safety, cost, and ease of use. Such criteria helped the team determine which ideas to scrap and which to keep. Of the many ways the team could solve the problem, the matrix helps them focus on the design that best fits the need.
Over the course of the year, the team came up with four tilt design alternatives, which they ran through their design matrix before choosing the one with the highest score. That design has a center of gravity pivot and includes a single-locking pin, allowing the user to tilt the wheelchair back and lock it into place.
“Having a single pin creates additional design challenges because a single pin will have to merge two frames of the wheelchair at a single point and be centrally located,” says Ptacek.
One important goal of the team was to make as few changes as possible to the original chair. Fortunately, the design of the chair frame required only minor updates. They did make the new wheel frame wider, however, so the chair could sit within the frame of the wheels to give better safety, balance, and stability.
The most challenging part of the project was building a locking mechanism that would keep the chair in its tilted position. The solution eluded them all fall semester; they spent hours brainstorming solutions, but none seemed to fit. Ptacek and White even thought about the problem over Christmas break.
“We finally came up with our locking mechanism on the first day back from break, which was really exciting,” says Ptacek.
In early January, Ptacek, White, and two other students also visited Hope Haven’s facility near Antigua, Guatemala. They toured the factory and saw how the wheelchairs were built. They talked with workers to see how the different parts were used, what the machines are capable of, and what fixes the workers thought would be best. Then, they joined workers on the factory floor assembling wheelchairs.
What they learned helped shape how they moved forward.
“Originally, we thought we would set tilt positions at 15, 30, and 45 degrees, but they recommended that we have one 90-degree setting and then let the physical therapist or fitter drill the holes in the bar wherever they want to customize the tilt angle, depending on their needs,” says White. “It was really enlightening for us to be able to hear more specifically what they want.”
Someone else recommended a spring-loading pin rather than a locking pin, which they’re looking into.
“Some say that engineers engineer for what they think the problem is, but the user might have other needs,” says Ptacek. “To see the facility, interact with the people and their culture, and understand where the final product will be used, really helped put our project into perspective and provided a holistic picture as to what and who we’re designing for.”
The group has since built a second prototype of the pediatric wheelchair in Dordt’s 3-D printing lab. Ptacek says they’ll keep refining their design, doing bearing calculations, and working on their final product until they make their senior design presentation in May. They’ll also have to deconstruct their prototype to make sure that it fits in the shipping box Hope Haven uses.
“I’m a visual, hands-on person, so I’ve enjoyed seeing our product come to life,” says Ptacek.
“We know we’re designing something that will help someone,” adds Smith. “It’s highly likely that our design will be implemented in some capacity, because this is already a successful global program. That’s a gratifying feeling.”
Adding CAD Modeling and a Moveable Footrest
Every pediatric wheelchair starts off in Hope Haven’s wheelchair workshops or manufacturing facilities, where volunteers and workers refurbish or create parts for the wheelchair.
“These facilities have a base model of the wheelchair, but they don’t have official prints or drawings of the chair itself,” says Jaren Brue, a senior mechanical engineering major and member of the second team.
The parts of the wheelchair aren’t even labeled. This can be problematic, particularly if a piece breaks in the field. It’s difficult for a wheelchair owner to request a replacement part if they don’t know what the part is called.
Brue and his four team members are creating CAD drawings of the wheelchair through SolidWorks software and labeling each part in a way that makes sense to both Hope Haven and their disabled clients.
They are also creating a new footrest for the pediatric wheelchair.
“There are certain situations where a patient needs to stand up while in their wheelchair—perhaps to use the remaining strength they have or to get exercise,” explains Brue. “The current footrest design doesn’t allow for this. Our goal is to redesign the footrest so that it’s easy to move so that the patient can sit or stand when needed.”
Like the group working on the tilt mechanism, Brue, Caleb Kroese, Tanner Hulstein, David Van Woerden, and Caleb Koomans were drawn to the pediatric chair project because they wanted to make a difference in the lives of people around the world.
“In engineering courses, we talk about what’s a legitimate need and how to design a product holistically,” says Kroese. “With this project, there’s a legitimate need—these people don’t have a wheelchair that’s fulfilling all the things they desire. Hope Haven doesn’t have a parts inventory system or part models.”
“There’s history with this project, too, since Dordt students designed it first,” adds Van Woerden. “Everyone we’ve talked to has mentioned that the wheelchair is well-built, considering how inexpensive it is. So, it’s cool to be able to develop the design further in order to serve a broader range of patients.”
During the fall semester, the team spent much of their time modeling the wheelchair and designing preliminary parts for the footrest. They met with Saarloos at least once a week to get advice and stay on track.
They also learned to find the delicate balance between asking Hope Haven the right amount of questions.
“We learned how to ask efficient questions—so, rather than emailing Hope Haven every time we encounter a problem, we try to work through the problem on our own and see if we can come up with a logical way to solve the problem,” says Brue.
Brue, Van Woerden, and Koomans play hockey, and Kroese runs cross country, so finding a time to work together on their senior design project was a challenge, but they made it work. By the time they presented at the preliminary design review in December, they had started developing a simple numbering system using numbers and letters to indicate where parts were located on the wheelchair. They had also created an exploded drawing of the wheelchair—a diagram explaining the relationships of the various parts and part numbers.
“This creates a shared language around how the parts fit together,” explains Kroese.
They also came up with a final design for a footrest: a swinging one-piece footrest that needs minimal modifications and only requires two new parts and one new part design—a footrest block, which will be made of the same plastic Hope Haven already uses. Eventually, they figured out a way to latch the footrest so that it wouldn’t come off in rocky terrain.
In the coming months, the senior engineering majors will complete their designs and finish up their report; in May, they will share their design with fellow students, industry leaders, and Dordt faculty at the annual senior engineering design presentations. There’s still plenty to do, but the team remains motivated by the big impact the wheelchair has had around the world.
“This senior design project is more than just a learning experience to me,” says Koomans. “We’ve been given a lot of responsibility—we are working on a problem that we know needs to be fixed. It gives me pride and motivates me to do good work, because I know that the work we do will impact thousands of people.”
Connecting People with People
What stands out to Ethan Brue about the pediatric wheelchair senior design projects is how the students connect to the end user.
“One of the biggest challenges of engineering design isn’t necessarily in the technicalities but in imagining the user and trying to put yourself in their shoes,” says Brue. “A good Christian engineer asks, ‘How does the user feel? What uses do they have for this tool?’ When you can answer questions like these, you can better understand what it means to serve.”
Visiting manufacturing facilities where parts are created made students more aware of what goes into building the chairs; interacting with patients in Guatemala gave a basic understanding of what needs need to be met through these chairs. These experiences not only helped students gain a better understanding of the project but also helped them empathize with the wheelchair recipients as they considered adjustments to the original design.
“With any senior design project, we ask them to think about the social, historical, and ethical issues involved,” says Van Gaalen. “We want them to think about what the clients’ needs are and what stewardship demands there might be. We want them to think from a Christian perspective: ‘How do I come up with the best solution to a customer situation?’”
“I think the students like the direct personal connection with the pediatric wheelchair project,” adds Saarloos. “If you’re an engineer at a very large company, there are often so many degrees of separation between what you’re working on and the people who will be using the final product. With this project, students can directly see who’s using the product they’re working on. That has a big motivating impact.”
The fact that more than 20,000 wheelchairs have been shipped worldwide is ample evidence of how valuable and needed the pediatric wheelchair project is. In some ways, though, Brue believes the students are the ones who benefit the most from this design project.
“Their eyes are opened to needs around the world,” he says. “After they graduate, even if they find themselves serving regionally or locally, they’ll never forget that their world is not the whole world. They can empathize and understand perspectives and needs outside of themselves. I hope they don’t lose that—I hope that same understanding of who they’re working for and why they’re working as engineers trickles down into their work in whatever engineering industry they serve.”
Sarah Moss ('10)