Spin n’ Grin

Designers: Morganne Gagne, Jayson Garmizo, Gautam Meka, Lydia Ran
Client Coordinator: Robbin Newton
Supervising Professor: Dr. Laurence Bohs

Figure 1. Spin n’ Grin.

Figure 1. Spin n’ Grin.

INTRODUCTION

The client is a young boy with sensory defensiveness, exhibiting strong negative reactions to external stimuli such as touch, sound, and taste. The best methods to calm him are spinning and vibration. The goal of this project was to develop a motorized spinning device that he can safely operate independently. The design includes a circular platform driven by a gear motor, and two large vibrating buttons that power the device only when pressed down. Internal sprockets and chain set the rotational speed to 9 rpm, which is optimal for the client. Using this device, the client can calm himself independently, learn cause-effect relationships, and improve balance.

SUMMARY OF IMPACT

The Spin n’ Grin helps children with sensory defensiveness and limited motor ability to find a way to self-calm, develop balance, and understand cause-effect relationships. According to our client’s mother, “I like the product a lot… It’s perfect.”

TECHNICAL DESCRIPTION

The Spin n’ Grin (Figure 1) comprises a base enclosure, rotating platform, seat, armrests, and buttons.

The base enclosure consists of a ¾” medium density fiberboard (MDF) box, 1’ in height, which surrounds a 2’x2’ MDF base. For ease of transport, two handles bolt onto each side of the base. The base enclosure encases all of the mechanical components. A 14 rpm, 12 V DC gear motor mounts at the corner of the base, supported by four steel S- brackets and two aluminum diagonal braces. On top of the motor is a 3/4’’ bore, 30 tooth sprocket attached to a 40 pitch chain. The chain extends to a larger 46-tooth motorcycle sprocket, which is machined and welded to an automotive wheel hub (Jeep Cherokee). The motor turns the sprockets, which in turn spin the wheel hub. The difference in sprocket sizes reduces the spinning speed from 14 rpm to 9.1 rpm, which was determined optimal for the client during testing.

The wheel hub attaches to the MDF base by three pairs of  1.5”x 7.375”x 2.125” wooden blocks with 2.125 x 4.625” aluminum panels between each group of wooden blocks. The wheel hub bolts to a 0.5” diameter hole in the middle of each aluminum panel. A Jeep Cherokee brake rotor attaches to the wheel hub to provide further support for the platform by increasing the supporting surface area.

The base enclosure encases a bidirectional spinning circuit that determines which button is being pressed and controls the motor spin direction. An Arduino microcontroller collects input from IR receivers. If either button is pressed, a power transistor (BDX67A) turns on the entire circuit.  A double-pole, double-throw relay changes position depending on which switch is pressed, thereby changing the motor polarity and spinning direction.  Power is supplied to the motor by a 12 V, 10A wall-mount DC adapter that plugs into a coaxial jack mounted on the base enclosure.

The 2.5’ diameter rotating platform is made from 0.75” thick MDF and bolts to the brake rotor. Carpet foam is glued on to the platform and covered with a red plush fabric to provide comfort to the user. The red fabric removes easily for cleaning. A memory foam seat cushion attaches with Velcro to the top of the platform, providing a comfortable seat for the user. . The red fur fabric cover and memory foam seat cushion provide decoration, texture, and support for the user. IR wireless transmitters, connected to the user operation buttons, attach to the bottom of the platform.  These transmitters send different codes to the IR receivers and Arduino controller, depending on which button is pressed.   Power is supplied to the transmitters using an easily accessed battery pack of two AA batteries.

10” long, 4” tall plywood armrests mount to the top of the platform on either side of the seat. Commercial light-touch switches mount to the top of the armrests, providing user control buttons.  Vibrational motors mount under the buttons, providing the client with one of his favorite soothing stimuli whenever a button is pressed.  Buttons must be held down for the platform to rotate, reinforcing cause and effect.  The outside panel of each armrest hinges open for access to the AA batteries that power the vibration motors and IR transmitters.

Figure 2 shows the client using the Spin n’ Grin. Cost of components for the device is approximately $560.

Figure 2. Client using the Spin n’ Grin.

Figure 2. Client using the Spin n’ Grin.

 

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