P13211: Colisionless Rimless Wheel (Wired)
/public/

# Detailed Design

 Table of Contents 1 Week 9 Design Revelation 2 Detailed Block Diagram 3 Energy Flow Chart 4 Engineering Specifications to Customer Needs with Test Plans 5 Engineering Analysis - Equations and Calculations 5.1 Mechanical 5.2 Electronic Off-Board Storage 5.3 Timing Diagrams 6 Simulations 7 Drawings and Pictures 7.1 Mechanical 3D diagrams 7.2 Electrical Systems 7.3 Schematics 8 Motor Control Algorithm 9 Bill of Materials (BOM) 10 Risk Assessment 11 Detailed Design Review 12 Beginning of SDII

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## Week 9 Design Revelation

We went through several versions of actuation before we finally settled on one type. However, running simulations of our proposed system proved that our method would not work. So, we came up with a solution that works in simulation. It can be found at:
Methods of Actuation

## Detailed Block Diagram

Detailed Block Diagram

## Energy Flow Chart

Energy Flow Chart

## Engineering Specifications to Customer Needs with Test Plans

Engineering Specifications

## Engineering Analysis - Equations and Calculations

### Mechanical

• Physics of the system
• Losses due to friction
• Frame Design/Plate Selection
• Carbon fiber over foam
• Order all materials from Noah's Marine Supply
• Machine shop will cut out design
• We will lay carbon fiber and resin
• Very rigid
• Holes for plastic inserts so we do not crush foam in compression (from fasteners)
• Axle
• Assume worst case
• All torque in wheel is now in frame at time of collision
• Assume fall distance of 2 meters
• Assuming .0005 meters impact distance, frame would see 137.2 kN
• Our axle can handle (79.3e9)(pi)(.009525)^2/4 = 5650 kN in shear
• Braces
• Calculated for bending and shear of tubing
• Worst case: one frame would see 12.6 N-m or 115.5 in-lbs of torque
• Spreading that out over 5 braces, each brace would see (12.6 N-m)/[(.3556 m)*(5 braces)] = 7.09 N or 1.59 lbs
• This force would result in a flex of 0.0682 deg (0.032 in) over the length of a tube
• This results in 37 Mpa of stress, but failure would not occur until over 250 Mpa
• Fastners

### Electronic Off-Board Storage

Storage Comparison
Between 2 Mb and 144 Mb needed (2Mb for 1 60-second long trial with 10 16-bit inputs at 500Hz and 144Mb for 30 trials of 60 seconds with 10 16-bit inputs at 300Hz)
The verdict: On-board storage of microcontroller and development combined not enough for even a worst case scenario. Off-board storage is needed.

### Timing Diagrams

#### Single-step Analysis

Periodic motion from MATLAB simulation. All quantities are scaled by their maximum value.

A close up view of the periodic motion during one cycle. All quantities are again scaled by their maximum value, except for the total energy, which is plotted as a percent change from the initial energy.

A close up view of the actuation. All quantities are again scaled by their maximum value, except for the total energy, which is plotted as a percent change from the initial energy. The effect of actuation can be seen in the linear increase in the total energy of the system.

A close-up view of the collision. All quantities are again scaled by their maximum value, except for the total energy, which is plotted as a percent change from the initial energy. The discontinuities in all quantities are due to the collision.

## Simulations

### MATLAB parameter simulations

Current Prototype Parameter Values Proposed System Parameter Values Units of Parameter
Number of spokes 5 5 Quantity
Length of legs 0.4064 0.41656 m
Mass of frame 0.737 1.5 Kg
Inertia of frame 0.021 0.066 Kg m^2
Mass of inertia wheel 0.9108 1.25 Kg
Inertia of inertia wheel 0.00723 0.112 Kg m^2
k-value of spring 3 5 (10.88) N m / rad (lbs/in)

## Drawings and Pictures

### Mechanical 3D diagrams

#### Plate Fabrication Trial

Plate Fabrication Trial
In case the above link doesn't work:
/public/Senior Design 1/Plate Fabrication Trial 2012-11-16.pdf

### Electrical Systems

Microcontroller Development board:

#### Sensors

• miniature optical encoder (attached to motor)

### Schematics

#### Microcontroller setup

• Sensors to Microcontroller
• Pending
• Microcontroller to Driver & H-Bridge
• Pending
• Batteries

## Motor Control Algorithm

• Implementing the control algorithm in software

## Risk Assessment

Probability & severity on 1 - 3 scale, where a "3" rating in both cases means very likely and we are totally screwed, respectively.
Description Probability Severity Risk Factor Mitigation/Prevention Strategy Watchdog
Illness/time consuming obligations 3 2 6 Do not rely upon having time in the future to accomplish task All
Materials unavailable & long lead times 2 3 6 Determine parts orders as far in advance as possible. Where applicable, have alternative vendors lined up. Owen
Lag time of system from data collection to movement 2 2 4 Compile very accurate system timing diagram by reviewing each parts' delay and minimize delays where possible. Maddy
Real life does not match up with simulations and theoretical data (includes if actuation will actually work or not & general theory -> physical) 3 3 9 Run as many simulations as possible, double-check work, get as many professional opinions as possible before diving into system realization. Hao
Cost v.s. quality 2 3 6 Determine minimum requirements for quality Owen
Proper distribution of weight 1 2 3 Wise placement of devices Dan
Ability to obtain motor at all/in time 3 3 9 Keep looking, ask for help if needed Becky
Complete structure breakage (mistake, breaks during tests) 1 3 3 Design system (choose materials) to be strong Owen

DDR Presentation