June 17, 2011 | Andrew Steiner

Team Achieving Mobility spent two semesters, an estimated 1,800 hours and at least two all-nighters designing a motorized stroller for a particular customer: Isaac Postma.

Achieving Mobility, a senior engineering design team composed of electrical engineers Dan Evans and Matt Rozema and mechanical engineers Matt Last and Rob VanderVennen, spent two semesters, an estimated 1,800 hours and at least two all-nighters designing a motorized stroller for a particular customer: Isaac Postma.

A design for Isaac

Postma, age 10, has spinal muscular atrophy, a neuromuscular, degenerative disorder that restricts his movement and prevents him from sitting upright for long periods of time. But like his fellow 4th graders at Byron Center Christian School, Postma wants to move. The problem was, Rozema explained, that no company manufactured the kind of stroller Postma needed, and he had already outgrown his old model.

In September 2010, Calvin engineering professor Leonard De Rooy presented the senior engineering class with the opportunity to work with the Postma family. The team accepted.

Tackling complexity

Their first step was to brainstorm design concepts with Deb and Arden Postma, Isaac’s parents. The design had to accommodate Postma’s condition, his growing body and his increasing desire for independence. It had to be longer, taller and Postma had to able to operate it using only one finger. In order for Postma to see ahead, the team would have to mount cameras on the stroller and attach a monitor where he could see it.

The four engineers delegated the design tasks according to their skills. The electrical engineers handled motor control and power regulation: Evans took over the power regulation system, designing it from scratch. Rozema assumed responsibility for researching motor control algorithms and configuration. The mechanical engineers VanderVennen and Last designed the stroller’s frame and the mountings for the LCD screen and cameras.

Because of the cost and complexity of the design, Achieving Mobility relied heavily on donations, both financial and physical. “We knew, starting off, that this project would not be possible without having donations outside of Calvin College,” Last said, “so we started communicating with Isaac’s church.” Ivanrest Christian Reformed Church raised $5,000 for the project.

The team also recruited help from outside companies. The delicate process of welding the aluminum stroller frame was taken up for a reduced rate by Ebling & Son, Inc., Blacksmiths of Kentwood, Mich. The LCD screen and cameras, critical to the central design concept of increasing Postma’s independence, were donated by Gentex Corporation of Zeeland, Mich.

As the project moved forward, the team frequently consulted the Postma family on their design, making alterations to the prototypes as needed. Designing the stroller proved to be less challenging than coordinating production schedules, given the number of third parties involved, Rozema said. Last agreed: “We had to adjust our schedule according to the third parties and make sure everything was set when the component got delivered, so we didn’t waste any time.”

Down to the wire

The project demanded the greatest share of time as the year was ending. “Finishing the project really came down to the wire,” Last remembered, “and the last two weeks really tested us as a team to focus and get everything done.”

Two days before the team was to debut its design at the engineering department’s annual Projects Night on May 7, Rozema and Last got an unpleasant surprise. “There was a loose connection in the wiring,” Rozema recalled, “but (the stroller) appeared as if it was broken.” The revelation of the simple problem didn’t come until well into the next morning: The two were finally able to leave around 6 a.m. “Needless to say we were relieved that it was only a loose connection,” Rozema said.

Worth the effort

Unlike many of the design teams who never meet those who benefit from their work, Achieving Mobility was able to witness Postma get into and drive his stroller for the first time. For Last, seeing Postma’s joy at the freedom to control his own stroller vindicated the long hours of work: “An ecstatic Isaac driving down his school hallways over and over again is an image I will remember for the rest of my life.”

Since graduating, Evans and Last have gone back east. Evans was recently accepted into a graduate program at Duke University in North Carolina. Last has been hired as a project engineer at Bechtel Plant Machinery, Inc. in Pittsburgh, working on the nuclear power system used by the Navy. VanderVennen and Rozema have remained in west Michigan, working at Gentex and Johnson Controls, Inc. respectively, where they will be on-hand to make adjustments to Postma’s stroller if needed.

The most gratifying aspect of the project, Last and Rozema agreed, was the chance to serve someone. Rozema summed up: “I was given an opportunity to use my abilities to benefit a family that has been through so much, and this has been absolutely priceless.”

See the Grand Rapids Press article at MLive for a video of Isaac Postma driving his new machine.

Left to right: Matt Last, Rob VanderVennen, Matt Rozema, Dan Evans and Isaac Postma

3D model of stroller

Electronic control unit, motor controllers and test motors

External contributions to Achieving Mobility

Ebling & Son, Inc., Blacksmiths: welded stroller frame at reduced rate

Gentex Corporation: donated LCD screen and cameras

Ivanrest Christian Reformed Church: donated $5,000

Johnson Controls, Inc.: donated printed circuit boards for power regulation

Mary Free Bed Rehabilitation Hospital: produced bedding and restraint system at reduced rate

Texas Instruments: donated printed circuit boards for motor control

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