Each year the Rehabilitation Engineering Research Center on Accessible Medical Instrumentation (RERC on AMI) conducts a national student design competition in which students are given a specified project goal that should meet the needs of provided client profiles. The chosen proposed project is an accessible weight scale that must ultimately be a convenient, low-cost weight scale that meets the needs of select clients. The scale is primarily designed for clients who are weak, overweight (up to 400lbs.), have poor eyesight, clients who are deaf, or clients who may need to closely monitor their weight. Thus, the project goal is to design a scale that meets the criteria set forth by then National Institute of Health (NIH) while also creating a design that could be feasibly marketed for personal, in-home use.
The team completed the phase I work plan which included a proposal of design, a patent search, Food and Drug Administration (FDA) requirement search, American’s with Disabilities Act (ADA) recommendation search, and a Small Business Innovation Research (SBIR) report. The patent searching reaffirmed that there are indeed other wheelchair scales on the market, yet none seemed to match the specifications set forth by NIH.
With all the clients’ needs taken into account, the team set the specifications for the project. The scale will be able to weigh patients digitally in both pounds and kilograms to the nearest ½ lb. and the scale will produce a weight measurement in less than 30 seconds. The scale will be accurate to within 1% of a calibrated scale and will be verified using volunteers that fall within the specified weight range. The scale will have a capacity of 400 lbs. and will also accommodate patients weighing as little as 80 lbs. The scale itself will have dimensions large enough to accommodate standard, non-motorized wheelchairs and the weight of the wheelchair will be included in the scale output reading. The ramp from the floor to the weighing surface will be in accordance with ADA standards which states that the slope of the ramp will be in proportion to 1”/12”. The final product must also be manufactured for less than $2000, as stated in the design competition rules.
Phase II of the design process consisted of materials purchasing, the construction of the proposed design, and the testing of the final product. The majority of the materials were purchased from local suppliers, and the scale used in the design was purchased through the internet. The welding on the aluminum scale base was contracted out to local welders and the remaining construction was completed by the team in on campus machine shops. The circuitry of the scale was also adapted to the frame by the team members. The testing of the scale was conducted at the Netum Steed Varsity Athletic Weight Room where the wheelchair scale was tested against the weight room’s calibrated scale using a series of weight plates ranging between 25 and 400 pounds.
Overall, the scale met all of the specifications and requirements stipulated by the NIH competition. The team also feels that the scale is very user friendly and that the hazards associated with it are minimal, therefore ensuring the safety of the team’s clients. After the testing the wheelchair scale, the team concluded that the all the requirements and specifications were verified and validated.