Scott Zitek - Fab Academy 2014

Applications and Implications

Week 16 Assignment

The assignment for this week is to plan and document a final project that integrates the range of units covered. We also needed to answer a series of questions about this project.

What will it do?

It is a low cost portable electro-mechanical scoreboard that displays the score for a sports competition. Through simple controls the digits representing the scores for each team can be modified.

I have additional information on my final project concept page.

Concept drawing of a two piece version of my portable scoreboard.

Who's done what beforehand?

I have not seen any previous examples of the approach I plan to take. However, here are some examples different methods:

Mechanical / electro-mechanical / electro-magnetic

• Lentus - a digital-mechanical clock using transparent strips
• Reflectius - a concept clock that uses a single laser beam to display digital numbers.
• Segmentus - a digital clock with hands.
• Clock using several small servos to move the segments outward instead of a more traditional way.
• Split-flap display, flip-disc display (or flip-dot display)- Remember the old alarm clocks?
• Flipdots – currently commercially available electromagnetic displays.

Electronic / Solid-state

• Incandescent bulbs
• LEDs - This is probably currently the most common approach for indoor and night time displays.
• Although LED are getting brighter and cost are going down, complexity and costs are still an issue. Especially when making large digits where many LEDs are needed. LEDs can also be hard to read in bright direct sunlight.
• 7-Segment Display - 6" (Red) digits at $15 each
• 12” digits starting at $50 each

I looked into available low cost scoreboard options available from Walmart

• Manual flip scoreboards $25 - $46
• Indoor scoreboard with remote $363 (LED lit score digits are only 4.25-inches)

What materials and components will be required?

• Enclosure – wood and/or acrylic
• Display components – acrylic, vinyl/paint, and/or maybe laserable multi-layer plastic
• Microcontroller (one or more)
• Actuators – eight servo motors (maybe stepper motors or DC motors)
• Misc. electronics components - battery
• Misc. hardware – nuts, bolts, washers, clips, and handles….
• Wireless radios (optional)

Where will the materials come from?

Common fab lab inventory items and local home improvement store

How much will it cost?

Depends somewhat upon size of display - I want to keep price down. $50 or less for a large 4 digit scoreboard with 12" digits would be a reasonable starting target for material costs.

• Enclosure – wood and/or acrylic ($15?)
• Display components – acrylic, vinyl/paint, and/or maybe laserable multi-layer plastic ($10)
• Microcontroller (one or more) - $1.50 - $2.50 Each (<$10)
• Actuators – eight servo motors (maybe stepper motors or DC motors) - $2.00 – 4.50 each. ($16-$36)
• Misc. electronics components
• Misc. hardware – nuts, bolts, washers, clips, and handles….
• Wireless radios (optional)

What parts and systems will be made?

When possible, practical, and cost effective, parts will be made. Obvious exceptions are microcontrollers, electronics, and servos.

What processes will be used?

• Computer-aided design - design segment patterns, etc.
• Computer-controlled cutting - laser cut parts
• Electronics production - custom circuit board(s) creation
• Electronics design - custom circuit board design(s)
• Computer-controlled machining - Shopbot cabinet components
• Embedded programming - convert digits desired into multiple coordinate servo positions.
• Input devices - simple operator interface
• Output devices - RC servo motor control
• Networking and communications (Optional) - wireless user interface?, communication among boards if distributive system is used.
• Mechanical design, machine design - sliding digit segments

What tasks need to be completed?

I have made a couple of prototypes of the display mechanism for the Mechanical Design/Machine Design week assignment. So I basically still need to:

• Build new display
• Build cabinet
• Design, mill, solder, and program electronics
• Assemble, adjust, test, document, etc.

What questions need to be answered?

• How to drive the segment slides several linear inches using the 180 degree rotation of RC servo?
• I plan to use a rack and pinion but it has not been tested.
• Will software PWM work or do I need to use hardware PWM to control the RC servos for the precision/resolution that I will need?
• Do the RC servos / control system have the precision, resolution and stability to move-to and hold the positions I need?
• How many RC servos can an ATTiny45, ATTiny44, ATMega328, and ATMEGA16 control?
• How many and which microcontrollers should I use?
• Could control entire system with one microcontroller
• or could use a distributive system with perhaps one microcontroller per pair of digits.
• Do we have all of the microcontrollers, servo motors, radios, and other electronic components in stock that I will need?
• Is there a simple way to add a wireless remote control?

What is the schedule?

Mechanical (2 days)

• Cut and assemble digit mechanism: half a day
• Design and implement drive mechanism: half a day
• Design and implement servo motor mount: half a day
• Test and optimize digit mechanism: half a day

Electronic (3.5 days)

• Design circuit board(s) – depends on number of boards and complexity of circuits: allocate a full day
• Mill and solder circuit board(s) – depends on number of boards and complexity of circuits: allocate a full day
• Initial programming of microcontroller to test servo motion: half a day
• Programming of microcontroller to move combination of servos to correct position for desired digit: allocate a full day

Structural (1 day)

• Design and cut frame: half a day
• Assemble frame, add hardware: half a day

Wireless remote control (if time permits): (2 days)

• Research and ordering: full day
• Circuit interface: half a day
• Programming: half a day

Note: I try to expect the unexpected. However, with typical interruptions, conflicts, equipment availability issues, and complications it may realistically take up to three times longer.

How will it be evaluated?

• Has at least one digit been created that demonstrates the mechanical design works manually?
• Has at least one digit been automated to demonstrate that the design can be electronically controlled?