introduction
This week is devoted to development of the final project: a masterpiece that integrates the range of units covered. The project should incorporate:
- 2D and 3D design
- Additive and subtractive fabrication processes
- Electronics design and production
- Embedded microcontroller interfacing and programming
- System integration and packaging.
Where possible, you should make rather than buy the parts of your project. Projects can be separate or joint, but need to show individual mastery of the skills, and be independently operable.
See Final Project Requirements for a complete list of requirements you must fulfil.
The answers to the questions below will allow you to create your BOM (Bill Of Materials).
Propose a final project masterpiece that integrates the range of units covered, answering:
- What will it do?
- Who’s done what beforehand?
- What will you design?
- What materials and components will be used?
- Where will come from?
- How much will they cost?
- What parts and systems will be made?
- What processes will be used?
- What questions need to be answered?
- How will it be evaluated?
Your project should incorporate 2D and 3D design,
- additive and subtractive fabrication processes,
- electronics design and production,
- embedded microcontroller interfacing and programming,
- system integration and packaging
Where possible, you should make rather than buy the parts of your project Projects can be separate or joint, but need to show individual mastery of the skills, and be independently operable.
Parts and manufacturing in the works...
Final Project Description
The final project’s design is covered on these pages. Based on the lecture and goal of this week I discuss relevant points here (so, a big reflection) - the design files and BOM are kept on the final project design page
modular synthesiser
I am aiming to design a new sound generator that would work in a modular synthesiser. In the world of music the first sound synthesisers were often built on (modular, rack mounted) lab equipment such as signal generators and filters. Doepfer and other manufacturers set a standard for rack sizes, power distribution, signal levels etc. This resulted in quite common characteristics for analogue modules, working with voltages between 0 and 10V, using 1V/octave, etc. The only odd-one-out is a triggering system by Moog (called s-trigger) which uses switching a current loop rather than applying a voltage. Also MIDI (in the 1980’s) offers a great deal of standardisation. Needless to say, my project should:
- make intersting sounds (thats what it will do :)
- be compatible with the existing modular synthesis ecosystem:
- use 1V/octave
- standard trigger/gate, CV and modulation input
- be MIDI compatible
Since there is a wide community of users, builders, DIY-projects-turned-into-products, there is a quite a state of the art. In my case I can borrow from:
- Pico based audio projects
- sizes, specifications of MIDI and (Doepfer’s) modular synth design work
- other modular synth designs, especially from the well documented work by Mutable Instruments
My design will consist of a small wave sample player-looper shaped as a creature, in this case a furby. The idea is to have a furby faceplate that moves in sync with the played sample/loop. Many ideas are already out there using furbies, also for musical purposes. My contribution will be:
- size accurate 3D printable animatronic Furby Face
- rack-mountable module containing face and control electronics
- control electronics compatible with music standards, playing and using samples as ’looper’ and ‘granular synth’
- user control inputs for live performance
The Bill Of Materials contains
- a custom PCB with electronic components and sub modules
- control software
- a rack module compatible mounting plate
- small 2.5mm screws and a 10-pin IDC flat cable for mounting the module in an (existing) rack
- RC servo tendon drive system (externally, separate from the module)
- 3D printed furby face (eyes, beak, fur)
The detailed list is given on the design page. In the list also the suppliers are given but in the main they are:
- PLA (lab suppliers, scrap materials from lab)
- electronics (Farnell , TinyTronics OpenCircuit, Amazon)
- RC servos (hobbyking), steel cable (staalkabelstunter), PTFE tube (Amazon), tendon mount (Reely - Conrad.nl)
- PCB (Aisler)
- fur/fabric (Pipoos hobby supplies store)
- vacuum plastic (Mayku brand)
- eyes (HEMA epoxy glue, nail polish, acrylic paint)
A quick estimate of the material costs gets into the 50-75,- range. Relatively expensive parts are
- the PCB (Aisler, 14,- including P&P)
- the Pico (6,-)
- the OLED (7,-)
- the PCM5102 DAC (10,-)
- RC servos (2 x 5,- = 10,-)
- ..
The BOM for the electronics is most detailed and can be generated using KiCAD. Here is the version imported in LibreOffice:
Electronics BOM from KiCAD
Most of the electronic components were still in (home) stock, some of the special ones such as voltage regulator, zener diodes and SD card socket needed to be bought, in this case at Farnell:
Order list at farnell
In terms of make parts rather than buy I choose to make the faceplate material myself (from scrap PLA), make they eyeballs (rather than store-bought), 3D print the furby mechanism (rather than use an existing). For now I have ordered the PCB at a boardhouse instead of making it on the milling machine, but when time permits I’ll try and rework the design into a single-layer board.
The manufacturing process consist of assmebly (and testing) of the following sub-parts before integration:
- The PCB containing all electronics (assembly, soldering, programming)
- a faceplate including fur covering (scrap press (optional, laser cut, vacuum form)
- a 3D printed furby face (3D printing)
- a tendon drive mechanism (3D printing)
Technical integration consists of
- connecting the tendon drive mechanism to the face mechanism
- mounting the face mechanism on the faceplate
- assembling the PCB
- mounting the PCB under the faceplate, connecting two RC servos
- mounting the assembled module in an (existing) synthesiser rack
- Rock.
product evaluation
Technical testing (QA) in the lab prior to comission consist of:
- electronics testing (optical, short circuit, power consumption, magic smoke)
- electronics testing using software (inputs, outputs, communication)
- mechanical testing (face is moving, unobstructed, silent operation)
Next up: the user evaluation. Main questions are:
- does it work from a technical / control point of view: does it make sound, can the sound be influenced by user input and control input
- does it
rock(as in, is it fun, inspiring, crazy, surprising in the musical sense)
The last one has to be tested and evaluated in practice…. So for the final evaluation (also for the video) I have to bring the module, get an audience and make it perform..
learning outcomes
- Define the scope of a project
- Develop a project plan including a bill of materials (BOM)
evaluation checklist
- What will it do?
- Who has done what beforehand?
- What will you design?
- What materials and components will be used?
- Where will they come from?
- What parts and systems will be made?
- What processes will be used?
- What questions need to be answered?
- How will it be evaluated?
lessons learned, tips and tricks
(or, the most insightful mistakes I made)
- The mechanism to control the eyelids and beak proved a little bit more challenging than expected. I had to change the part designs a bit in terms of tolerances and spacing
- the Bambulab is much better for high-accuracy detailed technical parts!
- It is very nice to work with a reduced, well matched component set (like the fab inventory)
left for todo
- assembly and testing of the electronics
- assembly of the mechanical face plate, face mechanism and bowden cable drive
- integrate both
- expand the software
reflection
Interesting week with a lot of planning, ordering components, boards arrived on time. Mechanical design is more work than expected but. I decide to put most of (this week’s) files on the ‘design’ section.