The Design Process - FRC

The Design Process
For

FRC Team 1592
Bionic Tigers

Mr. Christopher Bearden
Patriot Systems Engineering
cbearden1@cfl.rr.com
Twitter: @C_Bearden
321-777-2369

Video Presentation

If you would like to watch a video of this presentation, please
click on the following link :

The Design Process Video

Purpose

• Describe the engineering process used
by industry

• Relate the engineering process to the
FRC

Developing a System
5 Major Phases
Analysis Design Build Test Support

• Strategy

• Requirements = Design Reviews
Analysis
• Preliminary Design

• Detailed Design
• Fabrication

• Integration

• Design Testing

• Validation
• Defects

• Upgrades

Ideas Prototypes Finished Product


What will be our execution strategy for this work?
Specialities
1. Mech Eng - Pneu, Propulsion, Fluids
Roles & Responsibilities 2. Software Eng - Operating
Sys, Algorithm, Embedded
1. How are we organized to 3. Elect Eng -
execute the work? Radar, Power, Communications
2. Who is in charge of who? 4. Architects
3. Who is responsible for what? 5. Chemical Engs
6. ……..possibly many more!

Staffing
Development
1. Who is available?
Process Execution 2. Do employees have the
1. Design reviews
Strategy necessary experience?
(Program Plan) 3. Should we hire someone?
2. Parallel activities 4. Should we give some work
3. Schedule to another company?

Tools & Equipment Location of Work
1. Software – Lab View or C++ 1. Where will the work be performed
2. Engineering – Pro E or Autodesk (U.S. Or Overseas)?
Inventor 2. Do we adequate facilities at those
3. Machine shops locations?
4. Electronic manufacturing


What are we supposed to be building?

Types of Requirements
Sources of Functional Performance Physical Interface Services
Requirements

1. Customer What must How well must it What size, How will Besides the
Specifications this product perform this weight, people use product,
2. Marketing
do? task? color it? What what else
3. Safety
Standards must it makes it must be
4. Meetings be? work with delivered
5. Company Stds other (training,
6. Industry Stds products? documents,
Industry maintenance,
etc.)?

1. Game Rules Same Same Same Same Same
2. Team Strategy
3.
4.
Robot Manual
Awards
FIRST Robotics Competition
5. Arena
6. Meetings


Examples of Requirements

1. Minibot must ascend a metal pole and impact a
sensor disk. (Functional)
2. …..must climb the tower < 10 seconds
(Performance)
3. Sponsors logo’s will be displayed on HostBOT
(Physical)
4. A driver station will be used to control the HostBOT
(Interface)
5. HostBOT will not cross the vertical plane of an
opponents zone (Services – Operator Training)


What are the major pieces of our robot system?

ROBOT “System”

Operator

Driver Station “System” implies people, equipment
Host Bot and documentation

Need a design concept to
Chassis
get started

Manipulator

MiniBot

MiniBot
Launcher

Block Diagram


What are the ALL the pieces of our robot system?

Breakdown
Diagram


Requirements Brainstorming

• Technical teams meet to define the requirements for subsystems and
assemblies
– Functional
– Performance
– Physical
– Interface

• Example
1. The D/S allows an operator to control the HostBOT - Given

1a. There will be touch sensitive slider control to vary the HBOT speed
from 0 to MAX – Brainstorming Session

• Assign responsibility for requirements
• Software
• Mechanical
• Electrical

• Allocate requirement to the design
• Which Subsystem or Assembly does this belong to?


Preliminary Design Goal: Identify and assess alternatives for each of the
ROBOT subsystems (D/S, MiniBOT, etc). Choose one.

Step 1: Technical teams meet to propose solutions to the design problem.

Example: MiniBOT Design Concepts

Alternative #1: Use magnetic force to attach MBOT to the metal
tower and propel it upwards with an electric motor to impact the disk.

Alternative #2: Use a spring-loaded mechanism that clamps the
MBOT to the metal tower when the MBOT impacts the tower.

Step 2: Evaluate the alternatives.

Step 2a. Test the concepts using a mock-up or a model.


Example: Alternative #1 Mock-Up

Tape magnets to wood chassis; attach wheels; size it for the tower.

Knowing that the MBOT will need a motor, wheels, battery pack – find that
weight and add it to the mock-up – say 5lbs.

Test 1: What # and weight of magnets would it take to hold 5lbs
upright against the tower?
- How does this change as weight is added?
Test 2: How close to the tower must the magnets be?
- How does this change as distance changes?
Test 3: Do magnets affect the operation of the electric motor?
- What separation distance is needed?
Test 4: Will the MBOT travel in a straight line up the tower?
- How could this be corrected?


Step 2b: Consider the design constraints

a. Volume of MBOT is restricted to 12” x 12” x12”
b. MBOT must not weigh more than 15lbs
c. No more than 2 motors
d. Powered only by 12VDC battery
e. Allowed materials

Step 2c: What are the risks of this approach?

Ex: What if ……..the
MBOT falls off the tower
after impacting the
upper disk?

Can this risk be
mitigated somehow?


Step 3: Compare the alternatives

Alt #1 Alt #2 Alt #3
Performance 4 secs 5 secs 9 secs
Risk High Medium Low
Cost $ 100 $ 500 $100

Color Criteria:

Performance: if time <= 5 secs (Green)
>5<= 10 secs (Yellow)
>10 secs (Red)

Cost: <= $100 (Green)
>$100 <= $400 (Yellow)
> $400 (Red)

Step 4: Select an alternative


Step 5: Add design-level requirements to the existing requirements.

Example: Add what was learned from testing the
mock-up.

Step 6: Create a Preliminary Layout Diagram

Wheel Wheel

Gears

Motor
Battery Kill
Pack Magnets
Sw

Wheel Wheel
12” max


Detailed Design Goals: Identify specific parts and materials. Specify how these
parts interact.

Step 1: Identify the mathematical word problems and solve them.

Example: What gear design will propel a 5 lbs MBOT up the tower
at a speed of X inches/second using an electric motor with an output
power of……..a rotational speed of ……..and 4” diameter wheels?

Step 2: Identify parts

- Consider the design constraints from the Robot Manual
- Make it or buy it?
-- Cost limits imposed by FRC ($400 per part)
-- May need a detailed drawing if “make”
- Add parts information to the “Breakdown Diagram”
- Are there any “long lead” parts?


Step 3: Design the interfaces

What SW or HW must be added to the design to make the pieces
fit and function together ?
- HOSTBOT
-- Manipulator Assy
-- Chassis Assy
-- MiniBOT Launcher Assy
-- MiniBOT Assy

Step 4: Create the drawings and digital models

- Layout Drawings
- Electrical Schematics
- Fabricated Parts


The Build Phase Goals: Have a completed Robot system (including SW) that is
ready for testing.

Step 1: Drawings are released to machine shop (machinists, microelect, etc).

Step 2: Purchase Requests are released (a specialist in Industry).

Step 3: Transportation requirements are defined; materials are
purchased; crates are constructed.

Step 4: Parts are received and put into kits (a box or a shelf location)

Use the Breakdown Diagram
MiniBot
Manipulator Chassis Assy MIniBot Assy
Launcher
Assy Kit Kit Kit
Assy Kit

Step 5: Kits are assembled.

Step 6: Assemblies are integrated.


The Test Phase Goals: Test the performance limits of the product. Verify the
product meets the customer’s original set of requirements .

Developmental Testing

- How fast, how high, how far?
- Determining the safety limits
- Breaking points

Validation

- Prove to the customer that the product meets or exceeds
their original requirements

- Product ships when the customer is satisfied


The Support Phase Goals: Design new features for a fielded product. Fixing defects
that were discovered by users.

A new feature (i.e. requirement) sends you all the way back to
the Analysis Phase!
** What’s the implication here?****

Types of defects

- Software bug
- Parts that break too often
-- Environment (heat, humidity)
-- High usage
-- Poor quality

Replacement parts (or software) no longer made

Analysis Design Build Test Support Waterfall Development Process

How is Software different?
Process phases can be the same but different diagrams and products than HW.
SW development methods and tools very different than HW.
- Object Oriented Design
- Architecture Development Languages
- AGILE development
- Service Oriented Architectures

Analysis
- SW Architecture (versus Block Diagram)

Design
- Adding more detail to SW architecture
- Designing the interfaces to HW items
- Designing screen layouts
- Data structures, algorithms and sequencing

Build
- Writing and deploying code
- Version control
- Completing the SW architecture by integrating its pieces

The Last Word

80% of catastrophes discovered here


But they were caused here!

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The Design Process - FRC

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