Motorized Scooter

Motorized Scooter

Group Members

  • Aaron Cleek
  • Kurt Smith
  • Nick Heinold
  • Hassan Al Bazron

Introduction

For this project, we have been given the task of designing a “scooter board” that will be used by preschool aged children with arm and joint functionality problems. After meeting with our contact, Melissa Draper, we have come up with a list of requirements which we believe will satisfy the project needs. For a 3-4 ft tall child, the scooter board must allow a child to lye abdomen down, being able to shift his/her upper body weight to control the direction of the board. The child will need some sort of lever to activate a motor, allowing forward motion. The board must be designed so that it is stable enough to keep the child from falling off, but also flexible enough to allow the upper body movement and direction control of the scooter board. One of the main goals of this project includes designing adjustability to allow multiple users to benefit from the scooter. This will allow entertainment while building upper body muscle at the same time.

Design Specifications

Design Requirements:

  • Flat board design
  • Design must utilize upper body movement
  • User will be 3-4 ft. tall preschooler
  • Steering is controlled from weight shifted on elbows
  • Motorized design
  • Easy on/off button for motor control
  • Multiple user capability
  • Fun to ride beside building upper body muscles
  • Cost should meet the budget requirement

Design Concepts

Our Team came up with three different designs for this project.

Design Concept #1

For our first design concept the steering system will be controlled by the user shifting his/her weight onto their forearms causing a decrease in voltage to the motor on the weight shifted side of the scooter causing the scooter to turn in this direction. This will be done with a PWM. Also this design will have a seat and a place for the user to lay on there chest.

Pros:

  • small input from user
  • wouldnt take a huge input force
  • turning radius
  • completely weight shifted steering
  • ease of operation

Cons:

  • the complex wiring
  • cost of electrical components
  • time

Design Concept #2

A flat board, tricycle-like wheel configuration uses elbow pedal levers to steer direction of the board. Weight shifted on from user’s elbows force wheel to turn. The pedals are attached to linkages, that force shafts to move forward and backward, causing change in direction of the front wheel. A motor attached to rear shaft causes forward motion. Flat board enables user to lay flat while arching back.

Pros:

  • Easy to operate
  • Allows for small turning radius.
  • Board is stable, allowing minimal risk of user rolling off.
  • Basic, straight-forward design.
  • Satisfies all known requirements.
  • Linkage design inspired from exercise machine

Cons:

  • Not many options for battery storage
  • Design would only allow for a one speed motor only
  • May require high force for input
  • Input may be out of user’s ability
  • Not many off-the-shelf parts

Design Concept #3

This design utilizes four small hydraulic cylinders controlled the child's weight on the input arms to smoothly steer the scooter. Forward motion is provided by two gear boxes with motors connected to a 12 volt battery. The top speed will be between 2.5 and 5 mph. The steering mechanism will allow steering by the child simply leaning towards the way he/she would like to turn and depressing the input arm. Ideally the seat will need an ergonomic cut and possibly a small hinge to allow maximum motion of the child's upper torso.

flickr:5496225894

Concept Evaluation

After meeting with a group of engineers, we have given some advice for the things we need to consider in our design. They gave us some issues that we were not aware of and criticized our three designs.
We have evaluated our three designs considering the following criteria:

  • 1. Safety as our first priority: we don’t want a child to get hurt or fall off the scooter easily.
  • 2. Easy to use: The child should know how to use the scooter once he/she gets on it.
  • 3. Easy to build: The simpler the design, the better.
  • 4. Satisfaction: The design should satisfy the requirements that we are given.
  • 5. Maintenance: The design should be easy to maintain or replace parts.
  • 6. Cost of build: The cost should be within the budget.
Rated ( 1 ~ 5 ) | ( worst ~ best ) Design 1 Design 2 Design 3
Safety: 3 4 4
Easy to use: 4 3 3
Satisfaction: 2 4 3
Maintenance: 4 3 2
Cost: 5 5 2
Total 18 19 14

Design 1 and 2 were almost close to each other.
Our Team has finally made a decision to merge the two designs into a better design that will satisfy and meet all the requirements.
We have merged the simple structure of Design 2 and the electric mechanism of design 1 to come up with a new design.

Design Overview

Give a brief description and schematics of the final design. Divide into as many subheadings as needed for organization.

Analysis

Describe the three types of analysis performed on the design. Use equations and schematics as needed.

Engineering analysis #1

speed vs voltage vs trigger displacement

Speed (mph) Voltage (v) Displacement (in)
5 12 0.5
5 11
5 10
3.75 9 0.375
3.75 8
3.75 7
2.5 6 0.25
2.5 5
2.5 4
1.25 3 0.125
1.25 2
1.25 1
0 0 0
0 0 0
5578150973_6584b744a6_b.jpg

Engineering analysis #2

Turning Radius Analysis:

5578867732_abf0e5caa5_b.jpg

Engineering analysis #3

Engineering analysis #4

- - - Engineering analysis #4 - - -

5578883064_4fea6a783b_z.jpg

Bill of Materials

Part Purpose Supplier Size Qty. Price/part Total Price
Wood Board Aarron 1 n/a n/a
Sheet Metal Fender/ battery compartment Lowe's 24" x24" (22 ga) 1 $19.54 $19.54
Power Wheels Car Drivetrain Walmart dodge charger 1 $200.00 $200.00
Trigger Switch Elbow Sensors Ebay 2 $35.00 $35.00
Casters Front Wheels Lowe's 3" (125lb) 2 $6.48 $12.96
Bar Stock Support Handle Lowe's 1/8" x 2"x 48" 1 $12.59 $12.59
HSS Ribs/Axle Support/etc Lowe's 1" x 4' 3 $14.42 $43.26
Foam Board Cushion Hobby Lobby 2"x22"x22" 2 $7.99 $15.98
Imitaion Vinyl Durable Foam Covering Hobby LobbY per yard 2 $9.99 $19.98
Hinge Pedal Joint Lowe's 4" 2 $2.29 $4.58
Spring Pedal Mechanism resistance Lowe's 2 4.99 $9.98
Studded Knob Width Adjustment Lowe's 1.5" 4 $1.99 $7.96
Misc. hardware Lowe's misc 1 $45.00 $45.00
Tax: $461.83
Tax: $42.72
Total: $545.43

Part Drawings

Assembly Instructions

Implemented Design

Summary and Conclusions

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