BMR Racecar: Toy Car Adaptor Kit for Children with Impaired Mobility (University of Memphis)

Mobility device for children aged 1-3 with motor limitations

Bradley Bomar, Michael Mullins, Monica Rawson


Young children with motor limitations, such as cerebral palsy, may have hindered cognitive development at an early age due to limited experiences and mobility. Stimulating their learning and allowing exploration through independent mobility is needed to grow strong neuron pathways at their young stage in life. Our design solution is a mobile device called “BMR Racecar” that children aged one to three years old with motor limitations can operate to gain experiences in their environment.  Our design contains a specific designed adaptor kit that modifies a Lightening McQueen Power Wheels toy made by Mattel, Inc. The adaptor kit includes a redesigned seat, steering control, and power control. BMR Racecar provides a fun, safe, and cost effective way to develop independent mobility for these children. It has the potential to benefit thousands of children not only during their first few years of life, but offers a lifelong advantage of developed cognitive skills.

Background/Statement of Problem:

The physical experiences and interactions toddlers have with their environment significantly impact their development by triggering synapse formations [1]. Young children with motor limitations during this important window of brain development can be affected with lifelong hindered cognitive skills brought about by a minimal mental engagement with their environment [2].

Research shows a direct correlation in young children being independently mobile and their cognitive development. When children with motor disabilities are provided a way to be independently mobile, they increase cognitive development by active exploration of their environment [2].  Symptoms of limited motor skills can be caused from several different diseases in 1-3 year old children.  Cerebral palsy is the most common motor limiting disease in this age group, but others include spinal bifida, muscular atrophy, and a percentage of premature babies [3].

Mobility dependence in young children impedes lifelong cognitive development.  As a design team, we created a solution to allow these children to become engaged in their environment to enhance neural development and lead to improved quality of life.

Market Analysis

The market would be children, aged 1-3, that show motor limitation symptoms.  In the United States, cerebral palsy accounts for the majority of these clients.  Globally, cerebral palsy, premature birth, and spinal bifida account for the majority of mobility hindrance to young children.  The estimated U.S. (50,000 potential customers) and international (2.8 million potential customers) market sizes are conservative, because they do not account for undiagnosed disorders that cause motor limitation [3-7].  There could be the potential demand of 2.8 million units globally.


During the evaluation of the needs of the design control process, the team networked with a physical therapist assistant (PTA) to gain a better understanding of who the stakeholders were and what the clients’ needs were. The PTA granted the team the ability to make observations of these children with motor limitations and give the team guidance on what diseases to focus on. After vigilant analysis, the team considered cerebral palsy symptoms as a guideline to developing design specifications.  The thought out design needs included: an adjustable and supportive seat, an easy means of changing device direction, and an easy means of activating forward movement of the device, while maintaining economic affordability and easy device assembly.

After determining the needs, the team brainstormed and considered many solutions including a miniature seated Segway and a radio controlled mobility car which were both quite expensive. The team then methodically ranked and compared all solutions to select the most effective design.  The final design chosen was a novel adaptor kit that was specifically designed to modify an available toy car, which was collectively called “BMR Racecar.”


The BMR Racecar adaptor kit is a novel modification to an existing toy car, Lighting McQueen Power Wheels by Mattel, Inc.  The seat, steering and power controller were redesigned to meet the clients’ needs and has the potential to be packaged/sold as an adaptor kit.

Modified Seat

The novel seat was created to provide stability and support to the torso and the head, while remaining adjustable to accommodate as many different sized 1-3 year old users as possible.  This new design includes a tall back support, headrest, hip stabilization, padding, and a four point harness.  The seat was designed to have customizable foam density padding for varying body behavior and different sized hip stabilizing foam wedges to adjust for diverse body sizes.  This seat has a safety locking mechanism into the toy car body and is user friendly when assembling.  In addition, this modified seat can simply be removed and replaced with the original seat.

Figure 1. BMR Racecar Modified Seat


Modified Steering/Power Control

The innovative steering/power controller was design to address the client’s need of easy control over the device.  This modified controller combines changing direction function and motion initiating device together in one piece, called a “plug and play steering/power controller”.

The steering portion of the new controller decreases the force required to turn the steering shaft.  The moment arm of the steering controller was increased 25%, which decreases the force required to twist the shaft by 25% according to the torque equation, τ = F * r, where τ is the torque, F is the force, and r is the radius.  The adjustability of the “plug and play steering/power controller” was factored into the design by using a sliding pinhole system to change the position of the controller to best accommodate the user.  This sliding pinhole system allows for complete controller removal to be quick and simple, which allows for easy entry and exit of the user.

The redesigned power controller component of the “plug and play steering/power controller”, addressed the need of easy forward motion activation.  This element of the adaptor kit is a mechanical lever switch that contains the circuit to activate the motor of the toy car, resulting in forward propagation.  Vertical depression on the steering controller by the right or left limb turns a camshaft mechanism located in the center of the internal housing of the steering controller that depresses a switch.  The camshaft has to rotate only 5 degrees before it makes contact with the switch.  The spring in the switch applies an upward force on the camshaft that will push the lever up when the user lets go, stopping the toy car.  This mechanism decreases the complexity of the original toy car’s right thumb button switch and allows for users with minimal dexterity control or upper limb motor limitations to use this system.

Figure 2. BMR Racecar Modified Steering/Power Controller (shown without top housing and pin insert for internal details)


The final cost of this toy modification kit for children with mobility limitations is estimated to be 50 U.S dollars for all modified components. All components are made from an economical source of safe polypropylene plastic, polyurethane foam, cotton fabric, wires, and electronic button switches. When manufactured on a large scale, the seat and steering/power controller will be injected molded from polypropylene. This product could be manufactured in the U.S. and sold as an adapter kit globally via the internet.


A verification plan was developed to ensure that the BMR Racecar will be able to complete its intended use. The verification plan includes a three point bending test on the base of the seat and a deflection and stress test on the backrest (cantilever beam conditions). The steering control system underwent testing for fatigue in the turning and switch depression mechanisms. The seat held up to a safety design factor of three for maximum stress applied in many different scenarios.  The steering control system held up to a fatigue test to ensure that if the longevity of the material and design will last three years.

Though BMR Racecar seems to be in its last stages, it is undergoing continued product development to increase the efficiency of the design by lowering cost and materials. The seat is currently undergoing revision to accommodate a lower weight and still withstand the stresses the seat will undergo during use.


BMR Racecar grants the ability to kids with motor limitations to independently move around in his or her environment.  BMR Racecar design meets the needs of kids with motor limitations by providing a more supportive seat, so the child is able to sit upright and control the car efficiently and safely. Furthermore, this design meets the client’s needs by providing a steering control system that enables the child with low motor control in the upper limbs to control the car with efficiency. Considering all these design specifications were met, BMR Racecar is also an inexpensive adaptation that allows kids with motor limitations to develop cognitively while having fun.


Dr. John L. Williams, Dr. Gary L. Bowlin, Susan Anderson, NSF Grant (#1160107) BME Student Design Projects for Individuals with General and Age Related Disabilities


[1] “Baby’s Brain Begins Now: Conception to Age Three.” The Urban Child Institute. N.p., 2013. Web. 05 Sept. 2013. <>.

[2] Bulter, Charlene, EdD. “Effective Mobility for Children.”, 2009. Web.

[3] Centers for Disease Control and Prevention. Centers for Disease Control and Prevention, 06 Sept. 2013. Web. 06 Oct. 2013.

[4]  Netter, Lorraine, “Getting SSI for Premature Infants or Infants With Low Birth Weight”, Disability & Workers Compensation. Web. 05 March 2014. <>

[5] Martin, Joyce. “Births: Final Data for 2011.” N.p., n.d. Web. <>.

[6] Hamilton, Brady. “Births: Preliminary Data for 2012.” N.p., n.d. Web. <>.

[7] “Prevalence and Incidence of Cerebral Palsy.” The Ultimate Resource Everything Cerebral Palsy. N.p., n.d. Web. 07 Oct. 2013.<>

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