P16007: Motor-Assisted Wheelchair
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# Integrated System Build & Test with Customer Demo

 Table of Contents 1 Team Vision for System Level Demo with Customer 2 Mechanical Strength Analysis 2.1 Part (made of 1/8 steel plate) Strength Analysis 2.2 Strength Analysis 3 Mechanical Subsystem Assembly 4 Battery Box Layout 5 Plugs 6 Fully Integrated System 7 Risk and Problem Tracking 8 Plans for next phase

## Team Vision for System Level Demo with Customer

During this phase we sought to
• Find a working solution to mount the box
• Finish strength analysis and future recommendation for continuation
• Fully assemble the device and tests
• Start writing the paper for final report
• Prepare poster for Imagine RIT

During this phase we managed to

• Finish strength analysis
• Agree on how to mount the box
• Do a preliminary test of the system and make sure it will run
• Mount the battery box and make sure all components going inside box will fit.
• Start outline of the technical paper

## Mechanical Strength Analysis

### Strength Analysis

In COMSOL Multiphysics

• Keep the whole Mounting Piece fixed constraint.
• Load the inside bottom surface of the box with 45 N total force going down (about 20 lbs, z-direction in this case).
• Run simulation

#### Failure Analysis

The idea is to increment the loaded force until the total stress falls within 52 MPA (PVC ultimate stress)

• Change the loaded force to 1900 N (427 lbs).
• Factor of safety n = 28.

#### Storing Scenario Analysis

• Keep the mounting piece fixed constraint.
• Applied one force of 74 N going up at the mounting piece as shown in schematic.
• Applied another force of 74 N going down at the back of the box as shown in schematic.
• Applied a total force of 148 N (33 lbs., representing the whole system weight) on the inside bottom surface of the box.
• Run simulation.

#### Failure Analysis of Scenario

The idea is to increment the loaded force until the total stress falls within 52 MPA (PVC ultimate stress)

• The weight of the system stay at 148 N because we are simulating to see how much lifting force can the box withstand.
• Change the loaded forces going up to 575 N (129 lbs).
• Factor of safety n = 26.

## Battery Box Layout

We velcroed the batteries and the box so the batteries would stay in the box and not move around easily. The small circuit was also velcroed on the box but was not used for demonstration this phase. As one can see in the picture the small velcro will be where the circuit will go.

## Plugs

There was two main plugs designed so the user could remove the controls or remove the motor, batteries and battery box when the user wanted. The first picture shows the controls plug that has the PWM and the Rocker Switch. It will also connect to the E-Stop however was not connected this phase because of demonstration purposes.

The second picture shows the other plug that will connect to the controls plug, and has the motor power plug, motor controller plug, the battery plug, fuse, and the feedback wire. The feedback wire doesn't have anything connected this phase because of demonstration purposes.

## Fully Integrated System

The picture below shows the whole system integrated together. The things missing that we left out because it wasn't needed for demonstration purposes are the E-stop, battery monitor, buzzer, and circuit. We have tested all of them together and it does work when we have another switch which we are looking into either purchasing or finding.

## Plans for next phase

#### Team Vision

• Make exact wire lengths for design
• Heat Shrink Wires
• Drill Holes into Box to go to Motor Ports, Plug Port, and Charging Terminal Port
• Mount Controls Board onto Wheelchair
• Look into finding another SPST switch or purchasing DPST switch
• Wire with Small Circuit and Buzzer
• Test for appropriate speed of wheelchair
• Test for Lifespan of Batteries
• Test E-Stop for either completely stopping or stop power to motor and see which one makes more sense
• Fully assemble the device and tests
• Start writing the paper for final report
• Prepare poster for Imagine RIT
• Have a nice user manual in place when finished
• Have a great Imagine RIT experience