Penn Fall 2013 -- DeHon

Senior Design Skills and Advice

September 27, 2013Specification and

Concept Generation

Message

• Don’t Panic – about solving everything at once– Employ wishful thinking

• Don’t get stuck on first idea– Generate many– Mix & Match– Get Systematic

• Evaluate ideas against constraints and priorities

Penn Fall 2013 -- DeHon

Senior Design Intro

Penn Fall 2013 -- DeHon

Engineering Design Methodology

• Problem Definition• Requirement Ident.

and Analysis– Priorities

• Specification• Problem Decomp.• Concept Generation

– Brainstorming• Modeling

• Parameterization and Design-Space Exploration

• Benchmarking• Concept Selection• Prototyping• Implementation• Testing• Debugging• Evaluation

Engineering Design Methodology

• Problem Definition• Requirement Ident.

and Analysis– Priorities

• Specification• Problem Decomp.• Concept Generation

– Brainstorming• Modeling

• Parameterization and Design-Space Exploration

• Benchmarking• Concept Selection• Prototyping• Implementation• Testing• Debugging• Evaluation

Penn Fall 2013 -- DeHon

Specification

• Before can start solving– Need to know what your solving

• Before can evaluate “goodness”– Need to know what trying to accomplish– Priorities

Penn Fall 2013 -- DeHon

Quantitative Specification

• Typically need to – turn vague specification– into something quantifiable/measurable

• Something concrete

• From: fast packet processing– To: process 700B packets at Gb/s– added latency of 15 microseconds

Penn Fall 2013 -- DeHon

Specifications

• More of a trick/challenge for things that don’t have natural metrics– From:

• Door closes easily– To:

• Door latches with <5 lbs. Of force…– From: reliable– To: 1 failure in 109 hours of operation

• 1 undetected failure …

Penn Fall 2013 -- DeHon

Establish Priorities

• Which requirement is king?• Which have flexibility?

– Can tradeoff?• Ex: Requirements – quad rotor

– Cost in Volume (<$200)– Battery Life (>15 minutes of flying)– Payload (up to 1 kg)

Penn Fall 2013 -- DeHon

Establish Targets

• Acceptable Ranges• Ideal

• Usually Relative to alternatives/competitors

• Problem formulation should capture priorities

Penn Fall 2013 -- DeHon

RotoRouter Targets and Priorities

• Starting Point– Support TCP/IP– Operate with Introduction Based Routing– Logic fit in NetFPGA (gates, memory)

• Cryptographic hardware couldn’t be too large– Run at Gb/s line rate

• Cryptographic hardware must be fast– Detect and limit “bad” traffic

• Less than 10% impact on “good” traffic– Prevent tampering with packets

Penn Fall 2013 -- DeHon

Concept Generation

Penn Fall 2013 -- DeHon

Goal of Concept Generation

• Fully explore design space– Not miss options– Open minds to possibilities– Know what we can do

• Competitors can do

Penn Fall 2013 -- DeHon

Components

• Structured Approach• Partial Solutions• Uncertainty/Unknown• Documentation

Penn Fall 2013 -- DeHon

Non-Atomic Insight

Nothing will ever be attempted, if all possible objections must be first overcome. --- Samuel Johnson, 1759.

Penn Fall 2013 -- DeHon

Concept Generation: Steps

• Start refined problem specification1. Clarify/decompose2. Search

– Externally– Internally / brainstorm

3. Explore Systematically 4. Reflect

Penn Fall 2013 -- DeHon

Decompose

• Separate components must solve– Divide and conquer

• Maybe attack w/ separate passes through process

• Focus on bottleneck– Critical path/subproblem– Where most risk is

• Most innovation needed

Router Decompose

• Decide where packet needs to go• Switch packet• Ensure integrity• Ensure privacy• Validate packet wanted by destination

Penn Fall 2013 -- DeHon

Quad Rotor Decompose

• Propulsion • Location – how know where you are• Energy supply• Control and Stabilize• Motion Control• Route Planning• Payload pickup and hold

Penn Fall 2013 -- DeHon

Penn Fall 2013 -- DeHon

Search Externally

• Literature– Published / library– Web….google, IEEE DL, ACM DL– Patents

• Customers• Experts (faculty/research labs, advisors,

industry contacts)• Benchmark related / competitive• Understand state-of-art

Penn Fall 2013 -- DeHon

Search Internally/Brainstorm

• Common bugs: – Reject things too early

• “Nothing…” quote– Latch onto few ideas

• Get stuck in own local minima

Penn Fall 2013 -- DeHon

Search Internally/Brainstorm

• Different mode of thinking• Generate lots of ideas• Suspend judgment / no squashing• Grow mode / acid mode• Find good pieces, incomplete ideas• Wishful thinking• Comfortable with uncertainty

Penn Fall 2013 -- DeHon

Brainstorm

• Throw out ideas• Write them down … draw pictures• De-personalize

– Name by characteristics not person– Not attacking person/idea– Group ownership– Everyone contribute to debugging

• Friendly amendments

• Mix-and-match• Good science

– Find best ideas, avoid Not-Invented-Here syndrome

Penn Fall 2013 -- DeHon

People and Brainstorming

• Good to have both individual and group thinking times

• More brains generally good– Maybe limit size of group at a time– Different perspectives good

• Group ownership of final product– Involve stake holders– Build confidence in conclusion– Get buy in

Penn Fall 2013 -- DeHon

Systematic Exploration• Parameterized Design Space

– Knobs can turn to move between design points?• Concept combination matrix• Classification tree• Goals:

– Find holes– Over-emphasis– Make sure think about all cross products…

Penn Fall 2013 -- DeHon

Reflect

• Throughout process• Comfortable solving problem?

– Specification adequate?• Process

Message

• Don’t Panic – about solving everything at once– Employ wishful thinking

• Don’t get stuck on first idea– Generate many– Mix & Match– Get Systematic

• Evaluate ideas against constraints and priorities

Penn Fall 2013 -- DeHon

Time Permitting

• Work on example(s)– Decompose– Brainstorm

Penn Fall 2013 -- DeHon