Jun 15, 2020

Research has shown that having active control over one’s own exploration is linked to cognitive, social, motor, language, and other developmental benefits in young children. This type of independent exploration can be difficult for young children with mobility limitations; currently, there are no commercially available devices apart from power wheelchairs, which can cost thousands of dollars and usually are not an option until children are older.

What is the “Go Baby Go” organization?

“Go Baby Go” provides mobility and quality-of-life solutions to young children with movement limitations through modified ride-on cars (i.e., Fisher-Price power wheel cars). These cars enable children to move around independently.

“Go Baby Go” was founded as part of a research project at the University of Delaware but has expanded to universities across the United States, including my alma mater, Marquette University. This is where I saw firsthand the impact this simple device could have on a child’s life.

Since graduating, I have remained involved with “Go Baby Go” by maintaining a partnership between Marquette’s “Go Baby Go” program and Team 1675, a UL-sponsored FIRST robotics team I mentor that works with five different Milwaukee public schools: Rufus King High School, Ronald Reagan High School, Milwaukee School of Languages, Milwaukee Community Cyber High School, and Bradley Tech High school.

Our objective

Our team’s objective was to produce “Go Baby Go” cars based on a Marquette University senior design project of a car that can be operated similarly to an electric wheelchair. These cars would be used by multiple children in a clinical setting to learn how to operate a wheelchair before receiving one. As such, the joysticks needed to be adjustable to any location around the child while they were in the car.  

Use environment and intended users

The team needed to understand who the “Go Baby Go” users were and where it was going to be used in order to develop a car that offered the most developmental value.

Use environment: These cars would be used in a clinical setting with a healthcare professional (HCP) present.

Intended users: These cars would cater to two distinct user groups: children age 4-10 with movement limitations (operating the cars) and adult HCPs (setting up and monitoring children using the cars).

Usability considerations

After receiving and assembling their Fisher-Price car, our team discussed the components they would need to make the necessary modifications. The team considered cost, physical properties, and usability of the final car, along with the following questions:

Which intended user should be able to operate the harness?
Most “Go Baby Go” cars have a five-point harness (e.g., a car seat harness) to ensure that the child is secured in the car. Like a child’s car seat, this enables adults, including HCPs, to secure the harness and prevent young children from releasing it. The team considered whether this created a hazardous situation for the children if something happened to the “Go Baby Go” car, but ultimately decided the HCP will always be present when the car was in use. As such, the children did not need to be able to release the harness, because if something were to happen, the HCP would be present to remove it. Therefore, it was important to find a harness that could easily be used by an adult HCP.

Should the car always be powered?
Most current “Go Baby Go” cars, like the Fisher-Price car base, are always “on” (i.e., providing power to the motors and pedal) if the battery is plugged into the car. As such, wiring a joystick into the system as-is means the joystick would always be “on” (i.e., if the joystick is moved the car will move). This can present a problem when a child is getting into the car if they accidentally bump the joystick and the car moves. In order to address this issue, the team installed a breaker from one of their robots that enables the HCP to provide power to the car when they feel the child is ready. Additionally, this enables a child to get used to the tactile feedback of the joystick before it is powered.  

 

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What type of joystick is correct?
When selecting a joystick, the team initially thought that the size would be the driving factor, as it was important for the joystick to be large enough to be grasped by a child with limited motor control, but small enough to still fit in a child’s hand. However, after purchasing and wiring a joystick with digital controls, the team quickly noticed that the digital joystick’s user experience was not representative of wheelchair joysticks. Unlike a typical wheelchair joystick, when using a digital joystick, the car remained at a constant speed no matter how far forward the digital joystick was pushed, resulting in a jerky ride. As such, the team pivoted to an analog joystick that enabled a steady speed increase as the joystick was pushed forward. While slightly smaller, the analog joystick provides a much better user experience overall.

What material should be used to create a stable joystick arm with the required movement?
One major modification was the addition of a movable joystick arm, which needed to be easily adjustable to accommodate children of varying heights, but also rigid enough to withstand the force of a child resting their arm on it. The team initially considered using PVC piping because of its easy adjustability but found it was not rigid enough for a child to comfortably operate the joystick without the arm flexing or moving from its set position. The team ultimately decided to use a cymbal stand with a custom joystick holder, which enabled HCPs to adjust every joint without tools and provided sufficient support for a child’s hand.

Takeaways

The team does not typically design things for human use, so creating a product for a user in a use environment other than a FIRST field was a big challenge. Once we dove into the project and separated tasks by component, the challenge seemed much more manageable. The mechanical team learned that a component’s design must be considered from a human-centered perspective and that they could not simply look at the mechanical features, such as joystick size, without also considering how the joystick is controlled. The electrical team learned that the skills they have learned in FIRST can be transferred to systems and components outside of the “standard” FIRST components, and some might even improve the usability of current systems.

Currently, our “Go Baby Go” car is being programmed. After programming is complete, the first working model will be delivered to a local clinic in Milwaukee, WI. Once in the clinic, we plan to keep an open line of communication with the clinicians to continue improving our “Go Baby Go” car design.

Molly Erickson is a Human Factors Specialist in the Human Factors Research & Design division of Emergo by UL.

Learn more about HFE and usability testing for medical devices:

  • HFE user research support for medical devices and IVDs
  • Medical device and product evaluation and usability testing
  • Webinar: Human factors engineering for medical devices

Author

  • Molly Erickson

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