When Paul Rosa was 15 or 16 years old, his grandma, Paula Partilla, was losing mobility at a rapid pace.

She needed a power wheelchair, but not one that would be controlled by a joystick. No, she needed one that would be controlled by her eyes. He thought, “I need to help my grandmother. I don’t know how in the hell I’m going to do this.”

He started experimenting with robots, algorithms and reading books at his Naperville home. After nearly 30 tries at making a chair that would fit all of his grandma’s needs, Rosa finally built the perfect chair: the AutoChair. To move, all the driver needed to do was look in a certain direction and the chair would move there. This chair made Partilla capable of doing so many things, but — in Rosa’s terms — it was a slice of turkey on a cheese pizza.

Rosa quickly learned how to open Microsoft Word and, of course, a programming editor. He then started learning how to write code and began creating lots of list boxes in. Then, after some help from his dad, Rosa made his first computer invention, a traffic simulator. He wanted to figure out why cars didn’t collide when they made right turns at intersections.

Outside of school and programming, Rosa had a close relationship with his grandma. She lived next door to the Rosa’s and Paul would invite her over to play everyday. They would commonly go to zoos, playgrounds and aquariums to watch dolphin shows.

Partilla also cooked for Rosa though he said quality is a relative term when it comes to food.

“Well, good cook can have a lot of meanings to it,” Rosa said. “Healthy? No. Delicious food? Yes.”

However, one day during a dolphin show, everything changed. Partilla fell down some steps and broke her foot. She went to the doctor and Partilla learned she had MSA-C, Multiple System Ataxia-Cerebellum, which affects the functioning of the nervous system. Paul said his family didn’t tell him but his grandma’s health continued to worsen.

Partilla was a happy but stubborn woman. When she started having trouble walking, her doctors requested that she use a walker. She refused.

“She was determined that she was going to keep her mobility,” Rosa said.

But, her refusal to use her walker caused continuous, harmful falls.

Eventually she had to forgo the walker for a manual wheelchair and once that became too difficult, her doctors insisted she use a power wheelchair. Similar to her transition to the walker, Partilla was hesitant to leave her manual wheelchair.

However, she made the switch but soon even controlling a power wheelchair became too difficult for her and she needed something customized.

Rosa took it upon himself to find a solution, and it needed his full attention.

He started attending the Illinois Math and Science Academy, IMSA, in 2012.

In school, Rosa was the head of the school’s Programing Titan Robots First Robotics Competitions, co-founder of a game club and involved in the Advanced Computing Association.

After one year at IMSA, Rosa decided to drop out of school and enroll in “Paul Rosa University,” the name he gave his homeschool. There, he enrolled in such online classes as MIT’s Digital Signal Processing, Princeton’s Data Structures and Stanford’s Artificial Intelligence. However, his main focus was to help his grandma maintain her mobility.

He started building small robots and creating algorithms to make the robots move; the robots’ driving was staggered and not straight enough to make it through doorways.

“Then, I decided I should probably read a book or two on this,” Rosa said.

He read all the books about robots he could get his hands on, and said he then had a better idea of to how to create the AutoChair.

Rosa started customizing Partilla’s Hoveround, It was too big, and its front-wheel made driving and turning challenging. He decided to build his own chair. He grabbed salvaged aluminum, wood, computer parts and old wheelchair parts from around his house. He also 3-D printed some of his own parts.

“I’m pretty frugal,” he said. In the end, Rosa said the custom chair cost $500 to create.

Most modern power wheelchairs are made out of steel and are “absurdly heavy” at around 250 pounds, Rosa said. Additionally, he said they’re usually not very power efficient. Rosa wanted to create a chair that was much lighter — the AutoChair weighed 50 pounds — and also much more efficient.

He built the frame of the chair out of aluminum, which required no welding. The chair’s frame, which rested on two plains and consisted of 8-inch pieces of aluminum on the angled parts, was circular so it could turn better. The entire base moved itself in order to make better turns.

The seat was held a few inches off the base, which could have thrown the chair’s balance off center when driving on inclines or declines. But Rosa had a solution: The batteries, which are most commonly one of the heavier aspects of a wheelchair, would shift along gears to the center of gravity to balance out the chair.

Rosa then created a touch-screen control panel. The panel could play games — or at least he found a way to make it play games — steer the chair and diagn ose it for potential problems. But, as Partilla’s disease progressed, the touch screen became too difficult.

Rosa added a feature on the chair in which his grandma, with the help of a microphone, she could tell the chair where to go, and it would drive there. To prevent it from colliding with anything, Paul added sensors to the chair in which it could detect possible obstructions. And as a result, the AutoChair was born.

Later, Rosa would use the AutoChair to complete the ALS Ice Bucket Challenge in his grandmother’s honor.

Rosa returned to IMSA on April 29, 2014, not for schooling, but to pitch the idea of the AutoChair in a competition called Power Pitch for a cash prize. He also presented the idea to the Theil Fellowship, for the chance at a $100,000 prize. Though he didn’t win either of the competitions, the Theil Fellowship connected him with Katherine “Rin” Ray.

Ray, 18, graduated from George Mason University at age 16 with a bachelor’s degree in computational physics. She accepted the Theil Fellowship in 2014 and is currently studying elliptical theology in Chicago.

“She is somewhat intimidating to talk to,” Rosa said. Still Ray was able to mentor Paul on the rest of the chair.

But as Rosa was getting help with the chair, his grandma needed more help with her mobility, and she needed even more modifications. She needed a chair that could be controlled by her eyes. Once again, Rosa had a solution.

He added an eye-tracking device through which his grandma could look in a direction, and the chair would drive there safely. For example, if she needed to drive to the restroom, all she needed to do was look at the room.

This chair helped her keep her independence, but it didn’t help her health. On Aug. 19, 2014, Partialla, died at her home. She is survived by her husband, George, of 46 years, two daughters and six grandchildren. Upon her request, there was no funeral service. After an autopsy, there was no proof that she had ALS, or even, Parkinson’s.

“All we had was the diagnostic of MSA-C, which simply put, means that you are getting ‘holes’ in your cerebrum,” Rosa said. “We do not know anything more than that.”

Rosa said Partilla inspired him to make a difference in the world of wheelchairs and independence. He plans to continue the coding of his grandma’s chair to allow and different aspects of it. Though Partilla does not work with any specific company, he said he occasionally collaborates with Intelliwheels, a manual chair provider.

As a result, Rosa wants to continue “building cool things that help people,” he said. “I just want to help people.”

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Correction: A previous version of this article stated Paul Rosa works with Intelliwheels. Rosa is not an employee of Intelliwheels but collaborates with the company occasionally.