Vibration Pad For Activity Board

List of group members:

Robert Norton
Brian Wood
Wael Morshed
Anthony Campbell
Todd Baker

Abstract

Our group is designing a vibration pad that can be used by children with varying levels of transportability. Although the vibration pad will be part of an activity board, it will be highly mobile and operate independently.

Table of Contents

Introduction

The project our group has undertaken is to build a vibrating board for children. It is to be designed with handicap children taken into consideration, such as being wheel chair accessible. The design is to be simple yet efficient. Our goal is to make a board so that when the children stand on top of it they will experience a vibrating sensation from their feet throughout their entire body. We also intend on having the vibrations come through at different wavelengths so that the children are given different feelings throughout the time they step onto the board. The board is being designed in cooperation with another design group who is building an activity board. Our vibrating board will connect with the activity board so that when the children are using the activity board they will also be on top of our board. In doing this, we have agreed to add a button on the activity board that ignites our board into vibration with one slap. Then another hit of that button will turn the vibration board off. This gives the children the power to control when they want to experience the vibrations and when they want to stop feeling the vibrations. We have also decided to design the board with mobility in mind just in case the vibrations are wanted elsewhere or just simply for storage purposes. We begin design and construction of this vibrating board with the hopes and intentions of giving these children something fun yet safe to aid their day of learning.

Design Specifications

  • Simple to operate
  • Support the weight of a child
  • Ease of use and access for children in wheel chairs
  • Easily transported

Design Concepts

Design Concept 1

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Design Concept 2

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Transducer
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Function Generator

150 Watt Home Theater Amp

Design Concept 3

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Concept Evaluation

Design Overview

The details in the design where all taken into close consideration because of the variety of children that will be taking part in the use of our vibration board. The board dimensions are going to be a 3.5x3 feet board that is made out of plywood, which is just large enough for a child in a wheel chair to access. We chose this material because with the given dimensions it will easily be strong enough to hold a child in a wheel chair. On the top of the plywood, we will be adding grip tape to keep the children from getting splinters in their feet while also keeping them from slipping. The board will include three to four supports to keep the board as straight as possible through the duration of the boards use. The supports are going to be made out of 1’’X1’’ steel with a wall thickness of .12”. Underneath the frame we will include up to nine rubber feet. These rubber feet will be the only part of the board coming into contact with the floor. The rubber feet will be around 1in. in height to be just high enough off the ground so that the board doesn’t touch, but low enough for a child in a wheelchair to have no problem accessing. We chose rubber feet because this will keep the floor from being scuffed up and also it will keep the noise level of the vibrations to a minimum. The next and most important feature is of course the vibration motor. The motor we have chosen to purchase is an AC motor with a vibration intensity of 1, VAC of 115, AMP of .5, force of 15lbs, and runs at 1600 vibrations per minute. Along with the motor, we are including a variable speed controller called “The Speedster”. This will allow a change in vibrations from an 8AMP current rating with an input of 120 volts and a max amp of 15A, which will be controllable by either the adult or the children. This will allow whoever is turning the knob on the controller to increase the vibrations or decrease. We plan on attaching this to the activity board with Velcro so that when the vibrations board is being used by itself “The Speedster” can be detached. A case to envelop the motor will be built out of extra plywood to keep the children from being hurt. This plywood will also include the grip tape. Included in the design are wheels attached to the board so when lifted by the handle, which will be attached at the opposite end, the wheels will connect to the floor making transportation much easier. The life of our board was taken into extreme consideration, which is why we have chosen to use and do the things we have. We hope the children will enjoy their vibration board for years to come.

Analysis

Engineering analysis 1

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The System can be modeled in simulink as follows
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Through empirical experiment, we found that there is a gain between the output of the function generator and the actual force of of the linear driver. (Note the gain on our model of 0.17) A few of the group members were then set on the device and we discovered a good region for human damping to be around 22,000 N*s/m and the human spring constant to be in the area of 3,000 N/m. However, these numbers will change for different people. Now when working with a similar system the only thing changing will be the system spring constants, the amount of springs used, the amplitude from the function generator, and frequency. The gain for the model will depend on the motor chosen, and have to be if a different motor is used.ThERC.png
The results shown above are the displacement of the board and human in meters. The human used for the results has a mass of 95 kg and the mass of the board is 9.9 kg. The mass is entered into the simulink as 1/M.

Engineering analysis 2

Our original plan was to use a transducer along with a tone generator and an amplifier to create our varying vibrations for the board. But with further analysis, the transducer lifted the board too high off the ground and it only used one bolt to mount which after a short period of time we forsaw that causing problems with all the vibrations. So we all decided on purchasing an AC Vibrating motor along with "The Speedster", which is our variable speed controller, because this was much simpler and more effective.

Engineering analysis 3

In order to reduce noise and allow the vibrations to transfer throughout the board, our group decided to add rubber feet.

Bill of Materials

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Part Drawings

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Engineering analysis (Prototype)

Prototype (using linear transducer, function generator & signal amplifier)
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Testing protoype:
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Making adjustments:
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Assembly Instructions

Implemented Design

Summary and Conclusions