Background
Over 30,000 children sustain a severe traumatic brain injury (TBI) every year in the United States. In addition, cerebral palsy (CP) is a common cause of pediatric motor disability, affecting 1 in 345 children and 764,000 people in the US. Weak upper extremities and impaired manual dexterity can lead to slow, clumsy movements. Children with motor disabilities and limited mobility have fewer opportunities to engage in social activities such as sharing toys or playing with their friends.
This project is part of Project WHEELS, which introduces an innovative and playful ride-on therapy gaming platform for children with neurological impairments that complements the societal inclusion and community participation benefits of modified ride-on cars. This specific project’s goal is to develop a squeeze handle for children with neurological impairments to engage them for therapeutic purposes. When the children engage with the handle, the ride-on car physically moves forward.
Approach
As a mechanical research intern, I was responsible for designing, prototyping, and finalizing the design. In the beginning, I approached this project by using an air pressure sensor and a rubber duck. The rubber duck was chosen to encourage user interaction. A rubber tube connected the pressure sensor to the rubber duck, which held a plastic cone to hold the tube in place. While the design itself was unique and engaging to the children, during the first usability testing, I noticed that the connection tube wasn’t strong enough to withstand the children. Since different parts of the handle were made out of different materials, it was held by adhesive glue, causing it to fail.
From the initial design failure, I prototyped iteratively by using a force resistive sensor instead of an air pressure sensor. To continue user engagement, I replaced the rubber duck with a foam stress ball. The new design directly connected the handle to the sensor, removing the root cause of the previous design’s failure. I was in charge of designing and soldering the circuit board, 3D CADing the outer fixture in Fusion 360, and coding Arduino to receive signals. Using NMOS transistors and microcontrollers, I set the threshold of the force to flag a movement and translated the analog signal to digital to engage with the current motor settings.
Impact
I tested with 5 children and the handle remained intact during use. The usability test confirmed that the foam stress ball still keeps the user engaged and the set force threshold is adequate for the target users.