This project was suggested to Wright State University by the United Cerebral Palsy (UCP) of Columbus. One of their clients is employed at a home improvement warehouse and his employer would like for him to scan barcodes on the shelves to check for incorrect prices. The client is a fifty year old male with spastic cerebral palsy. Cerebral palsy is a movement and posture disorder characterized by increased muscle tone (stiff muscles) that results in difficult movement. He is wheelchair bound and suffers from moderate ataxia (shaking). The client's ataxia makes it difficult to hold the bar code scanner steady enough to scan a barcode.
The problem is to design a system that will securely attach a barcode scanner to a wheelchair without inhibiting the use of the scanner or of the wheelchair. The system must allow raising and lowering of the scanner, as well as triggering of the scanner and entering the data.
The first step that was taken in solving this problem was a patent search that showed no previous designs of this nature. Then, they began work on the problem by researching all of the components that they knew were going to be a part of the design. They researched the wheelchair the client used, the scanner the employer used, and the client's capabilities. Once all of this information was collected, they tried to think of all possible solutions. Then, they narrowed their search by discarding many of the possible solutions. They finally decided on one design and built a prototype. The prototype was then used for testing and fine tuning the system.
The prototype was modified many times before the best design was found. The way the system mounted to the chair was changed several times before the hook mechanism was utilized. A steel rod was added to the final design to help keep the pipe from bending. Most of the changes made to the model did not directly alter the system but increased it's functionality. An example of this was the addition of felt to the hook mechanism to keep the hooks from scratching the metal wheelchair frame. Final modifications were made to the system to ensure that all design specifications were met and the product was customized for the client.
The barcode system is constructed out of 3/4 inch PVC pipe. It measures 5 feet high, 10 inches across, and 5 inches deep. The entire system weighs less than 10 pounds without the scanner attached. There is a 4 1/2 foot steel rod inserted into the PVC to help keep the system from bending. The scanner is raised and lowered by ropes and six 1" rigidly mounted pulleys. The scanner's operating range is 14 to 55 inches from the floor. The system is not designed to lift more than 20 pounds.
The design goal was achieved in that the specifications were met. However, the final product was not as easy to operate as the designers would have liked. They recommend further work involving the scanner. They suggest internally wiring the scanner to a stereo jack located at the back of the scanner. A push button could then just be plugged into the jack to eliminate one rope from the system, which would help to lessen the physical exertion of the operator.
This design is very economical. Standard parts were used and can be purchased at any hardware store. The estimated cost of completing another system is approximately $68.00. The cost of the entire engineering design was $178.00, with the majority of the cost due to modifications made to the initial product prototype. The total cost was under budget by $122.00.
| Parts List | |||
|---|---|---|---|
| 2 | 5'3/4" PVC pipe | 3 | 3/4" PVC tee joints |
| 3 | 3/4" PVC ell joints | 4 | 3/4" PVC caps |
| 6 | 1" rigid eye pulleys | 1 | 16oz. PVC cleaner |
| 1 | 16oz. PVC cement | 1 | 41/2' by 1/2' steel piping |
| 6 | 10/24 lock nuts | 6 | 10/24 3/4" screws |
| 1 | 4" nail | 5 | 1/4" screws |
| 1 | cup hook | 5 | screw eyes |
| 5 | smaller screw eyes | 1 | 25' nylon rope |
| 1 | thinner 25' nylon rope | 3 | Velcro straps |
| 1 | buckled strap | 1 | sheet scrap metal |
| 1 | 10x8" wood board | 1 | paint stick |
| 1 | Velcro button | 1 | 2 square feet black felt |
| 5 | cans of spray paint (assorted colors) | ||
The system is designed so that it will be a very simple device to use for individuals with all kinds of medical problems. The handle bars were made in multiple colors so the user can identify each idividual color and the task it represents. The coords were made lengthy to avoid any reaching which is an added stress for the user. PVC pipes were used in designing the system to ensure sturdiness and a very light weight to avoid any titling hazards during the system use.
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