Ball Roller and Catcher

Designers: Christopher Chung, David Wang and Benjamin Wu

Client Coordinator: Leslie Loe, PT, Durham Public Schools

Supervising Professor: Larry Bohs

Our client, a five-year old girl with Rett syndrome, cannot communicate verbally and has decreased motor coordination of her arms and limbs, resulting in limited interaction with her peers. To promote socialization, we developed a device that allows her to roll a ball to a classmate at the push of a button, as well as catch it when rolled back. A push-action solenoid in conjunction with a lever rolls the ball, while a ramp system catches the ball and holds it in place. With this device, our client can roll a ball back and forth with a classmate.

The device helps our client interact socially with her peers. She is currently mentally aware of her surroundings and the events around her, such as when a ball is rolled towards her, but because of her disability she cannot respond. The Ball Roller and Catcher helps breach that barrier. As Leslie Loe, our supervisor said, “[she] will love playing with the device… [she] will benefit tremendously from playing with other students.”

The Ball Roller and Catcher (Figure 1) case is made of ¼” thick acrylic. The side, rear and bottom panels attach to each other using acrylic cement. The front panel is hinged to a downward sloping ramp located inside the device and opens to double as the front ramp, which slopes in the opposite direction from the inner ramp.

Two sheets of acrylic are cemented to the inner ramp in the shape of a V, directing the ball into the correct position and then holding it in place in front of the rolling mechanism. The rolling mechanism consists of a push-action solenoid acting upon a lever to propel the ball out of the box. The lever is constructed from a 3” long, ½” diameter dowel rod. It is attached to the acrylic support structure, which is also cemented to the back ramp. The solenoid is suspended above one end of the lever and fastened to the rear panel. When the switch is pushed, the solenoid activates, pushes the lever, and propels the ball forward.

An infrared LED and matching phototransistor pair are mounted on the inner ramp, beneath where the ball rests when “caught”. When the ball rolls into this position, it activates a series of LEDs located on the V-shaped holder, illuminating the interior of the device.

A rechargeable 12V DC battery pack powers the circuitry. Both battery and recharger are located in compartments behind the V-shaped holder. The recharging cable plugs into a port on the rear of the device. The top panel of the Ball Roller and Catcher attaches with four screws, making it easy to remove in the event that the battery needs to be replaced.

Also located on the rear of the device are a power switch and a 1/8” jack for the actuating switch. A red LED next to the power switch indicates when the battery requires recharging, illuminating only when the battery voltage exceeds 10V. The total cost for parts for the device was approximately $400.

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