Midway Design Review Advisor: Professor Russell Tessier Team: Michael Shusta Lucas Root Brandon...
-
Upload
rose-mcdaniel -
Category
Documents
-
view
216 -
download
0
Transcript of Midway Design Review Advisor: Professor Russell Tessier Team: Michael Shusta Lucas Root Brandon...
Midway Design Review
Advisor: Professor Russell Tessier
Team:Michael Shusta
Lucas RootBrandon Thorpe
Gilbert T. Kim
Outline• MDR Deliverables and PDR Concerns
• Development Approach
• Design Decisions and Progress
• Current and Projected Costs
• Patenting and Competition
• Meeting MDR Goals
• CDR Goals
MDR Deliverables PDR ConcernsFor MDR:
– IDB finalized with preliminary implementation– Locking mechanism design and prototype– Simple routines on the AIRcable– BlackBerry “hello world”
PDR Concerns:– Current and power requirements– Power storage and delivery– Cost of device in pilot run– Competing technology
Development Approach
• Weekly PowerPoints to update progress– Discuss and plan design of hardware and
software components – Group insight into individual problems– Motivate progress
• Team email account
• Subversion for code and group documents, repository of resources
System Overview
Client
Server
Bluetag Database
Store Inventory
Locked Item
System Elements
Server:IDB
IDB• Can establish RSA secure XML based
channel with client software• Can connect to and query the Bluetag
database as well as a demo store database
• Currently handles client requests synchronously, multi-threading is incomplete
• MDR goals met
Lock• Mechanism View via Prototype Demo
– Linear, Pull-type, Spring-Loaded Solenoid– Rotating Latch Holds Clothing Pin– Coil Suppressor– Solid-State Relay Control– See MDR Design Report for in-depth
discussion of physics, parts selection, force diagrams, etc.
SolidWorks View
•3D printed using ABS plastic/photopolymer resin•Assemblies can be verified/animated before fabrication
AIRcable Update• Purchased chip and hand-soldered to DIP
connector
• Ran simple routines on the AIRcable, met MDR goal
• Unstable system
• Discontinued product
line
AIRcable Debugging• Ability to connect to and program AIRcable
sporadic• Troubleshooting steps:
– Installed and learned Linux Bluetooth support– Visual inspection, ohmmeter check– Pin voltage under different operating conditions– Continued dialog with development team
• What went wrong?– Damage while soldering– Faulty chip– Damaged during operation
Tag Bluetooth Redesign• Separate module and microcontroller with UART
communication
• Roving Networks RN-41:– Small, low power, configurable, DIP breakout, low
cost, UART, widely used
• PIC 16F688:– Small, low power, low cost, UART, DIP, advanced
development tools
TXRX
RXTX
RN-41 16F688
Powering Bluetag• Bluetooth Module and Microcontroller
– Rn-41: 30 mA connected, .25-2.5 mA deep sleep at 3.3 V
– 16F688: 640 uA normal operation, 11 uA deep sleep at 3.3V
• Solenoid– SS2EP: 7W at 100% duty cycle at ~3.3V
Important Specification: peak power delivery of battery system must be at least 7.101W (solenoid + transceiving)
Battery Life EstimateAssumption:•The idle mode dissipation (8.23mW) of the control circuitry dominates its power demands
Performance Metrics:•One: Assume an up-time and estimate the maximum number of purchases•Two: Assume a maximum number of purchases and estimate the up-time
Powering Bluetag
Battery Life Estimate
t7
u3600108.23- -3
β is the total energy capacity of the battery system in Joules∆t is the duration of time the solenoid is energizedu is the number of hours between rechargingτ is the number of purchases
Ex. Let u = 8 hours, ∆t = 5 seconds and a battery of 8 W-h is used: lock would last 816 cycles before fully exhausting its battery
Ex. Setting τ=5 for an 8 W-h battery with ∆t = 5 seconds gives an uptime of 966 hours, or about 40 days
31023.83600
t7-u
What do these metrics tell us?•Battery must deliver high transient power a few times per charge•Clothing pin should be spring-loaded to minimize power draw window•Lithium-ion battery is proper choice:
-highest energy density per unit weight of commercial chemistries-available rechargeable, cell voltage near 3.3V-see MDR Design Report for in-depth discussion
What don’t these metrics tells us?•Probabilistic model of battery life (purchasing is a Poisson process!)•Relationship between mass, volume and capacity of batteries•Battery terminal design techniques
Powering Bluetag
Programming the BlackBerry
• Decided on BlackBerry JDE Plug-in for Eclipse– Involved configuration but familiar
environment
• Use of Simulators
• Enabled real-time phone monitoring
Basic Flow of the Graphical UIWindow One:
Input username and password
Window Two:Item ID entry
Window Four:Continue Shopping
Yes
Window Three:Item info & confirm purchase
Yes No
No
The BlackBerry UI APIs• Screen components
- Standard screen layout - Default menu
• Field components- Standard UI element for options, check boxes, lists, text fields &
labels, and progress bar controls
• Layout managers- Horizontal- Vertical- Left-to-Right flow
User Interface Progress
• Simple UIs using BlackBerry simulators
• Formatted and installed UIs on BlackBerry
Progress Block Diagram
HelloWorldLabelFieldRichTextField
Sample GUIHorizontalFieldManagerVerticaltalFieldManagerBitmapFieldBitmapLabelFieldBasicEditFieldEditField
Accomplished
Processing
Current and Projected Costs• Prototype Cost: $193 - $243
– PIC 16F688: $2.31– Lithium Ion Battery: $10– Ledex 2EP Solenoid: $20– Crydom SRR: $1– 3D Printing: $75-$125– PCB Fabrication: $50– RN-41: $34.91
• Development Costs: $49.66– PIC Development Board: $15.95– PICKit 3: $33.71
Patenting and Competition
• Met with CVIP Director Nick DeCristofaro– Proceed after prototype– One year window after disclosure
• Potential Competition Includes:– Phone based barcode scanners– Resonant tags with data storage– DoCoMo cell phone purchasing
MDR and CDR Goals• All MDR goals met
– IDB– AIRcable– Lock Design– BlackBerry Programming
• CDR Goals– UI completed– Full SolidWorks– PCB– Embedded Programming