.... EDGE
P08205: RP 1 Motor Module First Generation
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Establish Target Specifications

Table of Contents

Step 1. Prepare the List of Metrics

The table below presents the metrics, or engineering specifications, that will be used by the team to design against.

List of Metrics
Metric No. Metric Units Importance
1 Speed in/s 8/10
2 Acceleration in/s^2 7/10
3 Weight lbs 9/10
4 Number of Powered MM's delivered per team Units 9/10
5 Number of Idler MM's delivered per team Units 9/10
6 Size in x in x in 8/10
7 Steering Angle Degrees 8/10
8 Disassembly Time Minutes 6/10
9 Robustness Damage when dropped from tabletop 7/10
Customer Needs as Related to Engineering Metrics Matrix
Customer Needs vs. Metrics Matrix

Customer Needs vs. Metrics Matrix

Step 2. Collect Competitive Benchmarking Information

RP10 Motor Module

RP10 Motor Module

Benchmark 1: RP10 Motor Module
Appeal
Looks impressive with lightweight and transparent lexan sides
Shiny steel and aluminum
Exposed circuitry
Exposed drive system
Exposed "guts" lets users know how it works and is easy to diagnose problems
Use of bushings instead of bearings gives it a cheap and inaccurate feeling
Looks clunky
Could be a much more compact design
Size of turntable obviously determined overall design
Operating Characteristics
Large and awkward to handle
Drive wheel is easy to spin but lots of slop in drive system
I cannot readily tell how to use the product: Where do I plug it in? What orientation do I mount it in?
Product Teardown
1) Functions
Must drive wheel
Must turn wheel
Must be able to be addressed and controlled by platform
Must physically attach to platform
Must be electrically plugged into platform
2) Technology - Product employs:
Bevel Gears
Synchronous belt drive
Incremental encoders for drive and steering motors (US Digital P/N E5S-400-250-IH)
1 24VDC Drive Motor w/integrated gearbox (Shayang Ye Industrial Co. P/N IG420017-C520)
1 24VDC Steering Motor w/integrated gearbox (Shayang Ye Industrial Co. P/N IG320071-41F01)
Various electrical and control circuitry
Large turntable
Colson Hi-Tech Performa 5 x 1.5 Drive and Steering wheel
3) Strengths and Weaknesses
Large, clunky, homemade looking
Very big, definitely not 1/10 the size of the RP100 motor module
Visibility of "guts" is attractive and easy to diagnose problems
Incremental encoders cannot tell control system "where things are"
Had to extend motor shafts
4) Materials used
PCB's
Wires
2 DC Motors
Encoders for Motors (Qty 2)
Turntable
Bevel gear pair
Synchronous belt drive (rubber belt, plastic drive pulley, metal driven pulley)
Shaft couplings to extend shafts
Less than 1 ft^2 of 1/8" aluminum
About 5 ft^2 of 1/4" lexan
Miscellaneous fasteners
Zip-ties
E-clips for retaining shafts
Bronze Bushings (Qty 6)
Internal gear pair
Steel driveshafts
5) Manufacturing
Cutting lexan, aluminum, and driveshafts
Drilling lexan, aluminum, turntable, internal gear pair
Machining E-clip grooves in driveshafts
Pressing bushings into lexan
Fastening all peices together
Wiring components, holding wires with zip-ties
Experience and Knowledge
Design does not seem rugged, very fragile
Design seems imprecise
If you wanted to replace a broken part you would have to disconnect quite a bit to get to the part (eg. wheel, encoder, gear pair, shaft extension couplings, motor mounting screws, etc.)
RP100 Motor Module

RP100 Motor Module

Benchmark 2: RP100 Motor Module
Make use of quick disconnect wiring connectors
All wiring between platform and module and all module subsystems
Avoid the need for unscrewing wiring, which will add to ease of assembly
Wing nuts are good for quick assembly/disconnect
To remove EMF cage must disconnect every electrical component before the cage can be removed.
There are several areas on the module that can not be reached without an extreme amount of disassembly
No fall resistance
Too much slop in the turntable assembly
Meshing of gears (mainly the internal ring\spur)
Accessing internal gears
No warning labels
Imperfect welds
THK Cross Roller Ring

THK Cross Roller Ring

Turntables
Turntable used on RP100 and RP10 Motor Module:
Source: McMaster Carr
Part Number: 6031K21
Description: 9" OD 4.5" ID Galvanized Steel Bearing Turntable
Price (at benchmarking date): $6.14
Possible Options:
1) Manufacturer: THK
Description: Cross Roller Ring, Inner/Outer Type
2) Manufacturer: Kaydon Bearings
Description: Reali-Slim TT Series Turntable Bearings (Non-geared, externally geared, or internally geared)
Micro-Controller Units
1) Micro-Controller Unit used on P08201 Second Generation RP10 Robotic Platform :
Manufacturer: Crossbow
Description: MICAz 2.4Ghz Wireless Module
Website: http://www.xbow.com/Products/productdetails.aspx?sid=164
Notes: STUDENTS ARE URGED TO PURSUE THIS OPTION FOR A MICRO-CONTROLLER UNIT
2) Micro-Controller Unit used on Jeff Webb's Crawler
Supplier: SuperDroid Robots
Description: OOPic II Plus
Website: http://www.superdroidrobots.com/shop/item.asp?itemid=5&catid=2
Motor Controller
1) Motor Controller used on Jeff Webb's Crawler used to control GMH-04 Gearmotor (motor used on this year's RP1 Motor Module for steering)
Manufacturer: Texas Instruments
Description: TPIC0107BDWP Intelligent H-Bridge 180 MOHM 20-HSOP
Website: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=296-10857-5-ND
Notes: OBSOLETE ITEM - Students could find alternative
2) Digikey Tech Support suggested alternative to above item
Manufacturer: STMicroelectronics
Description: VNH3SP30TR-E IC Driver Motor H-Bridge 30-SOIC
Website: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=497-3565-1-ND
Competitive Benchmarking Matrix
Metric No. Need Nos. Metric Importance Units Benchmark 1 Value Benchmark 2 Value
1 Need 2,3,6,7,8,23,32 Speed 8/10 in/s 88.58 in/s Unknown
2 Need 2,3,6,7,8,23,32 Acceleration 7/10 in/s^2 49.8 in/s^2 Unknown
3 Need 21,23,32 Weight 9/10 lbs Unknown Unknown
4 Need 5,6,7,15,17,34,36 Number of Powered MM's Delivered Per Team 9/10 Units 3 3
5 Need 5,6,7,15,17,34,36 Number of Idler MM's Delivered Per Team 9/10 Units 4 4
6 Need 1-10,13,32 8/10 Size in x in x in 18" x 6" x 6" 19" x 6" x 6"
7 Need 2,6,21,23,25,31,35 Steering Angle 8/10 Degrees Infinite Infinite
8 Need 19,29,33,35 Disassembly Time 6/10 Minutes Unknown Unknown
9 Need 22,22,25,27,33 Robustness 7/10 Damage when dropped from tabletop Unknown Unknown

Step 3. Set Ideal and Marginally Acceptable Target Values

Set Ideal and Marginally Acceptable Target Values
Metric No. Need Nos. Metric Importance Units Marginal Value Ideal Value
1 Need 2,3,6,7,8,23,32 Speed 8/10 in/s 6 in/s 8 in/s
2 Need 2,3,6,7,8,23,32 Acceleration 7/10 in/s^2 12 in/s^2 15 in/s^2
3 Need 21,23,32 Weight 9/10 lbs 4 lbs 3 lbs
4 Need 5,6,7,15,17,34,36 Number of Powered MM's Delivered Per Team 9/10 Units 1 2
5 Need 5,6,7,15,17,34,36 Number of Idler MM's Delivered Per Team 9/10 Units 1 2
6 Need 1-10,13,32 8/10 Size in x in x in 10" x 5" x 5" 8" x 4" x 4"
7 Need 2,6,21,23,25,31,35 Steering Angle 8/10 Degrees Infinite Infinite
8 Need 19,29,33,35 Disassembly Time 6/10 Minutes 5 3
9 Need 22,22,25,27,33 Robustness 7/10 Damage when dropped from tabletop 2 hours of repair 20 minutes of repair
Design Requirements

General Requirements for all teams:

  1. Design will be tested on a flat 8' X 8'8" surface
  2. Each team will deliver 2 Drive (powered) and 2 Idler (non-powered) motor modules
  3. Design should be open source: all documents and designs will be public domain and all file types can be accessed by the public (eg. .IGES files that can be used by multiple CAD packages instead of types that can only be used by a single package)
  4. Design should be open architecture: all commercial off the shelf (COTS) components are able to be purchased from multiple vendors and all manufactured components are able to be fabricated using common technologies and tools
  5. Design should be powered by a DC power source
  6. Design will utilize components outlined in the Baseline Kit
  7. Designs will use encoders for information feedback of Drive and Steering Motor parameters
  8. Designs will use encoder signal feedback to the Micro Controller Unit for Motor Module navigation
  9. Design should be modular; can interchange modules on single type of platform and operate in a similar manner:
    1. All team designs will use the same interfaces for attaching the RP1 Motor Module to the RP1 Platform
      1. Physical attachment (eg. Bolt pattern)
      2. Electrical power and data connections (use of quick-disconnects is urged)
    2. All team designs will use the same interfaces for attaching the Communications and Drive Electronics to the RP1 Motor Module
      1. Physical attachment (eg. Bolt pattern)
      2. Electrical power and data connections (use of quick-disconnects is urged)
  10. Impressiveness of design interchangeability will be judged on:
    1. Highly Impressive: The ability to have ANY motor module designs on a single platform at the same time and drive the platform
    2. Impressive: The ability to have a subset of motor modules drive a single platform at the same time and drive the platform
    3. Expected: The ability to have a number of motor modules of the exact same design drive a platform
  11. Impressiveness of design communication will be judged on:
    1. Highly Impressive: Module can be individually addressable on a network
    2. Impressive: Module can be controlled by a communications protocol
    3. Expected: Module is at least able to be driven by a function generator and feedback read by an oscilloscope
  12. Design will physically resemble past projects (RP10 and RP100)
  13. Design will have a professional look and feel
  14. Design will apply the principles and practices in Design for Manufacturability and Assembly (DFMA)
    1. Utilize common components with other teams wherever possible to reduce costs and complications
    2. Design's manufacture and assembly time will be kept at a minimum
  15. Design will drive the Drive motor with a PWM signal
  16. All teams will drive the Steering motor with an identical type of signal technology
  17. All component should adhere to the overall RP Project family:
    1. Constraint Objectives
      1. Regulatory Constraints
      2. Academic Constraints
      3. Safety Constraints
    2. Resource Objectives
      1. People Resource
      2. Equipment Resources
      3. Materials Costs
      4. Labor Costs
    3. Scope Objectives
    4. Technology Objectives

Project P08202 Requirements

  1. Design will adhere to the general specifications for all teams
  2. Design will use the same COTS Motor Controller(s) as teams P08205, P08206 and P08208
  3. Design will use (if possible) the same Micro Controller Unit and supporting logic/communications components as P08206, P08205 and P08208 with an alternate communications protocol as P08206 (eg. If P08206 uses a CAN protocol, P08202 will use SPI protocol or I2C)

Project P08205 Requirements

  1. Design will adhere to the general specifications for all teams
  2. Design will use the same COTS Motor Controller(s) as teams P08202, P08206 and P08208
  3. Design will use (if possible) the same Micro Controller Unit and supporting logic/communications components as P08202, P08206, P08207 and P08208 but will communicate with a with a wireless device
  4. The Wireless Micro Controller Unit used will be responsible for receiving a wireless PWM signal and sending it to the PWM Motor Controller

Project P08206 Requirements

  1. Design will adhere to the general specifications for all teams
  2. Design will use the same COTS Motor Controller(s) as teams P08202, P08205 and P08208
  3. Design will use (if possible) the same Micro Controller Unit and supporting logic/communications components as P08202, P08205, P08207 and P08208 with an alternate communications protocol as P08202 (eg. If P08202 uses a CAN protocol, P08206 will use SPI protocol or I2C)

Project P08207 Requirements

  1. Design will adhere to the general specifications for all teams
  2. Design will use a custom PWM motor controller(s) developed by the team
  3. The custom PWM Motor Controller(s) will:
    1. Control the Drive and Steering Motors
    2. Operate in the same manner as the COTS PWM motor controllers chosen by teams P08202, P08205, P08206 and P08208
    3. Use the same input and output connections as the COTS PWM Motor Controllers chosen by teams P08202, P08205, P08206 and P08208
  4. Design will use (if possible) the same Micro Controller Unit and supporting logic/communications components as P08202, P08205, P08206 and P08208 with communications protocol of the teams choosing

Project P08208 Requirements

  1. Design will adhere to the general specifications for all teams
  2. Design will use the same COTS Motor Controller(s) as team P08202, P08205, and P08206
  3. Design will use (if possible) the same Micro Controller Unit and supporting logic/communications components as P08202, P08205, P08206 and P08207 with communications protocol of the teams choosing

Specifications

  1. A single RP1 Motor Module will be capable of propelling a robotic platform which carries a payload of up to 1kg in weight:
    1. Design is capable of variable speed from 0 to 9 inches per second when propelling a platform carrying a 1kg weight - Justification of Acceleration Specification
    2. Design is capable of an acceleration of 18 in/s2 when propelling a platform carrying a 1kg weight
  2. Design should fit within an 8" height X 4" length X 4" width size envelope
  3. Powered Motor Module design should weigh no more than 3 lbs each
  4. Idler Motor Module design should weigh no more than 1 lb each
  5. Motor Module Design should have an infinite steering angle around a vertical axis
  6. Should be able to access any component on the module with no more than 3 minutes of disassembly
  7. No more than 20 minutes of repair work should be made when the motor module is dropped from a tabletop

Step 4. Reflect on the Results and the Process

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Planning Mission Statement -- Staffing Requirements -- Intellectual Property Considerations -- Preliminary Work Breakdown Structure -- Team Values and Norms -- Grading and Assessment Scheme -- Required Resources
Concept Development Identify Customer Needs -- Establish Target Specifications -- Generate Product Concepts -- Select Product Concept(s) -- Test Product Concept(s) -- Set Final Specifications
System Level Design Product Architecture
Detail Design Design for Manufacturing and Assembly -- Robust Design -- Design for the Environment and Sustainability -- Design for Reliability -- Design for Safety
Testing and Refinement Prototyping