Research project on
the development of new tools for musical expression at the University
a robotic bassoon
This musical robot belongs to the category of our automated classical music
instruments: the bassoon. The reason for taking up a bassoon automation project
has to do with the simple fact that bassoon players of quality are getting extremely
rare. In fact, it should be considered an endangered if not already almost extinct
species... Furthermore, we do like the bassoon sound and thought it would be
a most welcomed timbral component in the robot orchestra. The brass section
is well represented and covers the bass side pretty well, but as far as woodwinds
go, there was a noticable gap. The approach here was an attempt to realistically
automate an existing and basically unmodified instrument, and thus it does use
a classical bassoon. We started the design of this robot after the quite successfull
realisation of our oboe playing robot <Ob>. Hence the sound mechanism
is based again on an acoustic impedance convertor with a capilary, driven by
a motor compressor. The original crook of the bassoon fits very precisely into
this part made on the lathe from massive brass. As
mandatory in such an impedance convertor, we first have an anticonical part
driven by the motor compressor leading into a capilary traject, after which
follows a conical part adapted to the instrument to be driven, in this case
the crook of instrument at the end where normally the double reed is mounted.
The longer the (linear) length of the capilary and the smaller its diameter,
the more the sound is determined by the acoustic properties of the instrument
alone, but obviously at the same time, sound pressure goes down. Thus we always
have to find a compromise. In this case we did choose the diameter of the capilary
at 3 mm and the length at 6 mm. As yet we have no mathematical model for this.
If a physicist could help us out here with some math it would be highly welcomed.
Sofar we sufficed by turning different shapes on the lathe and, by successive
approximation, getting to an optimum result. Very time consuming, indeed.
Here are some pictures of the bassoon we used, -a french Artla instrument-,
before any treatments took place, in the left pictures and after placement of
the valves in the right picture.:
From an acoustical point of view, the bassoon is a pretty poorly designed instrument.
It has a narrow conical bore with no less then 27 holes. A pretty complicated
valve and lever mechanism renders it possible for a human player to open and
close all these holes with just ten fingers. The resonance characteristics show
up a pretty low Q-factor for the fundamental note played and therefore playing
exactly in tune is pretty demanding for a human player and asks for a very good
lip control. Despite the many valves and mechanics. At the other side of the
medal though, this makes is possible, in a robotic design, to implement all
kinds of tuning and intonation subtleties even without using complicated fingering
Any automation project for an instrument normally played by humans, should
start off with a proper analysis of how it is traditionally played. Therefore
we started off with a thorough study of the textbook fingering table for the
From this study, combined with questioning a professional bassoon player, we
can learn which keys are acoustically fundamental and distinguish the ones only
added for the playing comfort of the musician. Trill-valves (3) as well as octave
speaking valves (whisper valves) may not be essential for a robot. Thus of the
27 valves found on the instrument, some can be considered optional. Also, it
revealed of interest to study some literature on the history of the instrument,
since that explains the growth of the mechanism into its present day state very
well. Note that on the baroque bassoon for instance, like on the recorder and
the traverso, many pitches were played using cross-fingerings. These are awkward
for players in fast passages, but there is no objection against them on an automated
Although we first considered leaving all mechanics on the instrument intact
and replacing the human fingers with action solenoids -this was what we did
in our automated oboe- , some early experiments revealed clearly that this would
lead to a lot of unwanted clicking noises. Therefore we decided to get rid of
all the mechanics and replace them entirelly with flat pallet solenoid valves
working directly on the tone holes. We took a risk here, as we mounted all the
valves directly on the instrument, knowing that the mechanical load on the wood
would be quite a bit higher than in the traditional instrument. To make sure
we would not crack the bassoon and ruin the internal bore, we constructed well
fitting saddles from 0.8 mm thick stainless steel plate, for each of the solenoid
valves and fixed them lightly with very short plate screws into the wood whereby
the real sticking force is realised by glueing the assemblies using a special
silicone compound. This job alone took almost a month of work, in part also
because the silicone compound takes about 24 hours to cure. The results of this
procedure will be clear in the photo collage underneath:
Once we got the sound driver and all relevant valves automated, we had to design
the electronic circuitry as well as a mechanical chassis to hold it all together.
For the electronic side, we first (that is, the version operational until september
2012) used a similar design as for the oboe <Ob> and most of the brass
instruments. Although a volume control circuit was added to improve on earlier
designs, we were not completely satisfied with the result. In september 2012
, after the good experiences with the realisation of our <Klar> robot,
we designed a new compressor driver board taking advantage of the 32-bit capabilities
of the ARM processor.
An important aspect of the firmware for the ARM processor used here, is that
we had to implement a formant around 500Hz in the driving source signal. This
conforming to the findings published by F.Fransson in 1966, where he proves
clearly that this formant cannot be attributed to the bassoon as a resonator
but solely to the action of the double reed. The formant filter implemented
affects the partials listed below. Note that notes higher than midi 60, do not
have this formant, note 71 being at the center of the formant frequency itself.
Calculation results for overtones falling within the formant range of the bassoon
Fundamental note , multiplier, frequency, fractional note
note= 34 partial: 9 frequency= 524.4343 note= 72.0391
note= 35 partial: 8 frequency= 493.8833 note= 71
note= 36 partial: 8 frequency= 523.2512 note= 72
note= 37 partial: 7 frequency= 485.0696 note= 70.68826
note= 38 partial: 7 frequency= 513.9134 note= 71.68826
note= 39 partial: 6 frequency= 466.6905 note= 70.01955
note= 40 partial: 6 frequency= 494.4413 note= 71.01955
note= 41 partial: 6 frequency= 523.8423 note= 72.01955
note= 42 partial: 5 frequency= 462.493 note= 69.86314
note= 43 partial: 5 frequency= 489.9943 note= 70.86314
note= 44 partial: 5 frequency= 519.1309 note= 71.86314
note= 45 partial: 5 frequency= 550.0001 note= 72.86314
note= 46 partial: 4 frequency= 466.1638 note= 70
note= 47 partial: 4 frequency= 493.8833 note= 71
note= 48 partial: 4 frequency= 523.2512 note= 72
note= 49 partial: 4 frequency= 554.3653 note= 73
note= 50 partial: 3 frequency= 440.4972 note= 69.01955
note= 51 partial: 3 frequency= 466.6905 note= 70.01955
note= 52 partial: 3 frequency= 494.4413 note= 71.01955
note= 53 partial: 3 frequency= 523.8423 note= 72.01955
note= 54 partial: 3 frequency= 554.9917 note= 73.01955
note= 55 partial: 3 frequency= 587.9932 note= 74.01955
note= 56 partial: 2 frequency= 415.3047 note= 68
note= 57 partial: 2 frequency= 440 note= 69
note= 58 partial: 2 frequency= 466.1638 note= 70
note= 59 partial: 2 frequency= 493.8833 note= 71
note= 60 partial: 2 frequency= 523.2512 note= 72
note= 61 partial: 2 frequency= 554.3653 note= 73
note= 62 partial: 2 frequency= 587.3296 note= 74
note= 63 partial: 2 frequency= 622.254 note= 75
note= 64 partial: 2 frequency= 659.2551 note= 76
For the control of the valves and the fingering combinations, we used a Microchip
18F4620 microcontroller, for it can handle many output pins. The board designed
has provisions for a maximum of 28 solenoid valves. Ample for this robot. The
firmware for this controller, making extensive use of lookup tables, was developped
with the Proton+ compiler in PicBasic combined with the MPLAB programming environment
offered by MicroChip.
The thirth and last circuit board, houses a small Microchip 18F2525 processor
and takes care of all visual aspects, including the motor implemented to give
the robot some physical movement possibilities. An analog input is used to read
the tilt sensor. This board serves at the same time as a midi-hub for the other
Obviously, the different components also need power. Hence we designed all
analog power supplies as needed. We carefully stayed away from switched mode
power supplies, since in all too many earlier projects they were at the origin
of many problems with reliability and audible artifacts.
Since some movement of the bassoon is quite normal in human performance, we
wanted to implement that as well. Hence we suspended the entire bassoon and
motor drive assembly on a spindle such that it is allowed to rotate over an
angle of about 30 degrees.
A novel aspect of the design of this robot is the implementation of a fingered
vibrato, conforming to the tradition in vibrato playing up to the second half
of the 19th century. (cfr. Baines, 1957). The standard midi channel-aftertouch
command was used to implement this. The lookup tables for the vibrato-activated
valves reside in the firmware and are not user programmable. The value parameter
for the aftertouch command is used to steer vibrato speed. Note that fingered
vibrato can be applied to any sounding note, included the lowest note. This
seems counterintuitive, as on a normal bassoon, as soon as any valve is opened
when note 34 (B-flat) is playing, another note will sound. In this case however,
we keep the excitation on the low note and use the valve opening the note an
octave higher for fingered vibrato. The lookup tables used for fingered vibrato
are based on carefull experimentation with the playing instrument. We remain
open for suggestions as to alternate fingerings.
The ambitus implemented for <Fa> is:
The circuit overview looks like: Details
can be found at the bottom of this page.
Only when integrated in the context of our Logos
Robot Orchestra with its wealth of varied sensor systems allowing full interactivity,
this automate becomes a true robot, with knowledge of the environment in which
it operates. That's after all were its destination is to be sought.
Midi Mapping and implementation:
Midi channel: fixed to 15 (counting 0-15).
Note Off: Implemented for all notes in the range. Starts a short decay (release)
on the playing note. The duration of the release is determined by the value
of the controller 19. For legato playing, note-off's can even be dropped, since
the instrument is monophonic.
Note On: Implemented for notes in the range (34-91) . Bassoon sound is only
obtained using the normal range 34-79 however. Velo-byte is used for the level
of the sustained sound portion. The lights are also mapped on notes, but make
use of a range outside the normal range of the bassoon, i.e. the 0-5 range.
For those lites the velo byte is implemented to make automatic flashing possible.
The velocity value determines the speed of the flashing. With value = 127, the
lites will be permanent on. With zero value, they will be off.
Controller 1 is used as a 'wind' controller and steers the noisyness of the
generated sound, by mixing noise in the drive signal. With value 0, the signal
is noisefree. A normal setting is 2.
Controller 2: LFO3 frequency applied to the filter. Default = 2. Advised setting:
Controller 3: Vibrato depth (LFO1 amplitude). Default = 20. Advised setting:
20, to turn vibrato off, set this controller to 0.
Controller 4: Vibrato speed. (LFO1 frequency). Default = 8. Advised setting:
Controller 5: Tremolo depth, amplitude modulation. (LFO2). Default = 0
Controller 6: Tremolo speed. (LFO2 frequency). Default = 0
Controller 7 is used as the general amplitude controller. This is the controller
to use for all slow amplitude modulation related effects. It should be avoided
to leave this controller on a high value (say above 80) for longer than required,
since there is a risk of burning out the compression driver at long high sound
Controller 16 is used to control the slope of the attack. At value 127 the
attack will be as steep (sudden) as possible. This controller will only have
an effect if preceded with a note-off command, this to render pure legato playing
possible. Decent sequencer software should offer you a possibility to set tracks
for the <Fa> robot to monophonic synth, such that note-off's can be dropped
from the sequence. A normal setting is value 80.
Controller 17 is used to control the maximum sound level during the attack
period. The normal value can be taken as 127 (maximum).
Controller 18 is used to control the duration of the note attack. A normal
setting is valkue 90. The interdependencies of these controllers together with
the velo byte is shown in the graph below:
Controller 19: Release time. If legato playing is in use (meaning we do not
send note-off's) the setting for this controller will be overridden. If you
use sequencer software that does not allow you to not send note off's, legato
playing can be obtained by setting this controller to low values. A normal setting
Controller 20: Tuning. The basic tuning of the instrument can be shifted a
quartertone upwards or downwards. At setting 64 the tuning corresponds to A=440
Hz. (Precision better than 1 cent).
Controller 21: Restricted use: steers mimimum motorspeed (only used for code
development and adjustment of the electromechanics), Default = 72
Controller 22: Inclination controller for the movement. Default = 0 (Fully
reclined position) . Value 10 corresponds to a fully vertical position.
Controller 23: Restricted use: steers maximum motorspeed (only used for code
development and adjustment of the electromechanics). Default = 120
Controller 25: This sets the central frequency for the formant filter. For
a good bassoon sound, one should stick to value 75 here.
Controller 26: Sets the Q-factor (the amount of resonance) at the formant frequency
set with controller 25. For a bassoon the value should be 100.
Controller 27: For experimental use only. Echo mix, can generate multiphonics.
Set to 0
Controller 28: For experimental use only. Echo feedack, can generate multiphonics.
Set to 0
Controller 29: LFO3 filter depth. Large values give a quite artificial wha-wha
effect. Normal setting: 21
Controller 30: Valve release time out.(only used for code development)
Controller 31: Does the same thing as aftertouch: fingered vibrato. However,
it does not require to be sent again and again in a sequencer. The parameter
sets the vibrato speed. Default = 0
Controller 40: Sets the range for the pitchbend command. Normally and by default
we stick to plus or minus a quartertone. When set to 0, pitch bending is disabled.
When set to 1 we have the normal default setting: -50 cents to +50 cents.
Controller 41: Detune amount of the first odd harmonic (duodecime). Not to
be used on the bassoon. Normal setting: 0
Controller 42: Intensity of the duodecome component. Not to be used on the
bassoon. Normal setting 0.
Controller 43: Wait time for the vibrato to be applied after the note-on command
is received. Normal setting: 20
Controller 44: Wait time for the tremolo to be applied after the note-on command
is received. Normal setting: 10. This can be used for flatterzunge effects.
Not in normal playing.
Controller 66: Robot on/off switch. Setting this to 0 resets all controllers
to their default start-up values.
Controller 67: Switches automated movement in function of the music played
on or off. The inclination of the robot is a function of average pitch. When
no notes are played, the robot will return to the reclined position.
Controller 69: Switches the automation of the blue eye-lights on or off. By
default this controller is set to on. Values <64 switch the controller off,
>= 64 switches it on.
Controller 100: alternate fingerings for the lowest 7 tone holes. Bit 0 is
the tone hole for Bb, on the upper part of the instrument, bits 1 to 5 control
the valves for the holes in the bass part of the tube. Bit 6 controls the lowest
tone hole on the lower part.
Controller 101: alternate fingerings for the next higher 7 tone holes, all
situated on the lower part of the instrument (this part has 12 holes)
Controller 102: alternate fingerings for the next higher 7 tones holes, 4 on
the lower part of the instrument (bits 0 to 3) and 3 on the high part. (the
high part of the instrument has 8 holes)
Controller 103: alternate fingerings for the last 6 tone holes. 5 are on the
high part (bits 0 to 4) and the last one (bit 5) controls the small octave hole
on the bottom of the crook.
Controller 123: switches the sounding note off, releases all keys, dims all
Pitch bend: The <Fa> robot can be used in any tuning system. In the drawing
below we give the coding example for a fragment of a quartertone scale:
Most good sequencer
software (such as Cakewalk or Sonar) use the signed 14 bit format. Note that
one unit of the msb corresponds exactly to a 0.78 cent interval. To convert
fractional midi to the msb only pitchbend to apply follow following procedure:
if the fractional part is <= 0.5 then msb= 63 + (FRAC(note) * 128), if the
fractional part is larger than 0.5, we should switch on the note + 1 and lower
the pitch with msb= (1-FRAC(note)) * 128. Note off should
reset the pitch bend for the playing note!
Channel Aftertouch: used for implementing fingered vibrato. The parameter sets
the vibrato speed. Note that vibrato cannot be applied to all notes! For note
34 for instance, all valves are closed and there is simply no valve to use for
vibrato. Sending the command is harmless at any time. If it is impossible, nothing
will happen. The parameter sets the speed wherewith the vibrato is executed.
Note that most sequencers reset the channel aftertouch after every note off.
To overcome that problem, we have implemented controller 31 as an alternative.
Program change: lets the user select alternate fingering
lookup tables. (not yet implemented)
Lights: The lights are mapped on very low midi-notes as follows:
- note 0: frontal yellow LED spotlight (3 W), mounted on the main power switch
- note 1: frontal yellow LED spotlight (3 W), mounted inside chassis
- note 2: frontal left red LED spotlight (towards floor)
- note 3: frontal right red LED spotlight (towards floor)
- note 4: eye lite, blue (right eye, backside right breast)[ these only work
when controller 69 is off]
- note 5: eye lite, blue (left eye, backside left breast) [these only work
when controller 69 is off]
The velocity value determines the flashing speed. If value 127 is send, the
lights will stay on without flashing. Value 0 switches the lights off. Whilst
a light is switched on the flashing speed can be further controlled using the
key-pressure command for the corresponding note.
- size: 1600mm (H), 480mm (W), 850mm (D)
- weight: 50 kg.
- transportation: needs a flightcase. The bell of the bassoon can be removed.
- power: 230 V ac / 200 W (Fused: 3.15A, fast)
- Tuning: based on A = 440 Hz (within 1 cent). The tuning can be adjusted.
- Ambitus: 34-79 (extended to 91)
- control: MIDI-input, 4 MIDI-Thru, 1 MIDI-out. (UDP/IP Ethernet port to be
- Insurance value: 16.000€
Design and construction: dr.Godfried-Willem
Collaborators on the construction of this robot:
- Johannes Taelman (ARM chip coding)
- Kristof Lauwers (GMT implementation)
- Sebastian Bradt (bassoon advisor)
- Bernard De Graef (bassoon advisor, fingerings)
Music composed for <Fa>:
Pictures taken during the construction in our workshop:
Na de bijzonder geslaagde realisatie van onze hobo spelende robot
<Ob> besloten we nu ook het lage broertje van de hobo, de fagot, onder
handen te nemen. Ook hier stond ons als doel voor ogen zo getrouw mogelijk de
werking van de traditionele fagot te mimeren.
Mikrotonaal spel, inklusief kwarttonen zijn mogelijk door toepassing
van non-standaard grepentabellen. Alternatieve grepen kunnen trouwens ook worden
toegepast om klankkleurvariaties te bewerkstelligen. De hele opbouw van de elektromechanika
voor het vingerwerk was uitermate tijdrovend, maar toch niet bijzonder moeilijk.
Het vereist wel heel precies las-, tap-, boor-, zaag- en snijwerk. Bij de uitwerking
opteerden we deze keer voor het geheel buiten werking stellen -en ook fysisch
verwijderen- van alle kleppen en hefbomen nodig voor de menselijke bespeling.
Het automatiseren daarvan zou immers onvermijdelijk tot vele overbodige bijgeluiden
aanleiding hebben kunnen geven. Bovendien zijn de vingerkleppen op de fagot
op sommige plaatsen (de duim bvb.) dermate dicht bij elkaar geplaatst dat het
gewoon ondenkbaar was elektromagneten toe te passen met heel kleine afmetingen
en toch voldoende kracht: die kunnen immers in het geheel niet worden gebouwd.
Wanneer alle kleppen verwijderd worden, blijven we met een instrument voorzien
van niet minder dan 27 toongaten. Elk gat werd voorzien van een eigen volkomen
autonoom stuurbaar elektromagnetisch ventiel. In rust zijn nu alle toongaten
dicht. De elektromagneten met de kleppen werden geheel op het lichaam van het
instrument gemonteerd, een behoorlijk risikovolle onderneming. Immers het hout
wordt nu belast met het gewicht van al die spoelen en er is dus een reeel risiko
op barsten en perforaties. Om dit risiko zoveel mogelijk te beperken, monteerden
we de spoelen op zadeltjes die op hun positie worden gehouden met uiterst korte
inox plaatschroeven en voor de eigenlijke hechting werden vastgekleefd met een
speciaal silikonen rubber (Loctite Bronze). Hierdoor wordt de kracht uitgeoefend
door het gewicht van de elektromagneten over een relatief groot oppervlak gespreid.
Voor het klankmechanisme opteerden we voor een krachtige motor
kompressor gekoppeld aan een akoestische impedantiekonvertor uitgerust met een
kapilair van 4 mm, overeenkomstig de inwendige diameter van het bokaal aan de
zijde van het riet. Deze konvertor werd uit een massief stuk messing met hoge
precizie gedraaid op de draaibank.
De elektronische schakeling bestaat uit enkele afzonderlijk funktionele
boards, de samenhang is zichtbaar in dit overzicht:
1. MIDI-hub board
Dit board en de 18F2525 processor staat in voor voor de lichten,
gemapt op de noten 0 tot en met 5.
2. Motor control board:
18F2525 PIC processor. Staat in voor de besturing van de motor
die het instrument doet bewegen. De firmware is struktureel gelijkaardig aan
de firmware eerder ontwikkeld voor de <Ob> robot. De midi output laat
toe de aktuele positie van de fagot in te lezen.
De PIC op dit board, een 18F4620, staat in voor het juist toepassen
van de vingerzettingstabel op de gevraagde te spelen tonen. Het PC board is
in wezen hetzelfde als wat we ontwikkelden voor heel wat slagwerk robots zoals
<Dripper>, <Casta>, <Troms>, <Psch>, <Xy> e.a.
De achtentwintig beschikbare mosfet driver uitgangen volstaan voor het aktioneren
van alle nodige kleppen. De firmware is uiteraard totaal verschillend. De Midi
input (in TTL formaat) wordt toegevoerd vanuit het midi-hub board. De 5V voeding
is autonoom on board uitgevoerd zodat we gevrijwaard blijven van power glitches.
Details van het schakelschema zijn te vinden onderaan deze web-pagina.
Een bij deze robot ingevoerde vernieuwing is de volledige implementatie
van vinger-vibrato, toepasbaar op elke gespeelde noot. Dit gaat terug op een
historische uitvoeringspraktijk waarbij vibrato niet met de lippen werd verkregen,
maar wel door een veelal lager gelegen toongat periodiek te openen of te sluiten.
De opzoekingstabel voor de vingerzettingen werd samengesteld op grond van metingen
en experimenten en ligt vervat in de firmware voor deze microprocessor.
4. Rietbesturingboard (Versie 1.1, nu versie 1.2):
Hiervoor konden we hetzelfde printontwerp gebruiken dat we eerder
ontwikkelden voor <Aeio> en dat gesteund was op prototypes ontwikkeld
en gebouwd voor robots zoals <Korn>, <Hurdy>, <Autosax>, <Ob>
en <Bono>. Ook hier werd eenzelfde PIC mikrokontroller toegepast: de Microchip
dsPIC30F3010. De transformator was gebouwd naar een volledig eigen ontwerp door
het bedrijf Sowter in Engeland. De toepassing van een transformator hier was
ingegeven door de zekerheid dat we nu elke DC offset kwijt waren en bovendien
door toepassing van geschikte kondensatoren, konden zoeken naar de meest optimale
formant. De dsPIC firmware voorzag ook in de mogelijkheid ruis toe te voegen
aan het stuursignaal (via midi controller 1) waardoor het bijgeluid van speeksel
en lucht in het riet kan worden gemimeerd. Het dynamisch bereik bleek evenwel
onbevredigend en het was moeilijk een automatisch vibrato en tremolo's op het
dsPIC platform te implementeren. Daarom wijzigden we het gehele opzet van de
kompressor driver in 2012 alsvolgt:
In deze versie maakten we gebruik van een 32-bit processor op
een ARM discovery board. Dit bood heel wat meer mogelijkheden voor controllers
en filters in de firmware. Ook de dynamiek kon heel wat groter worden dan wat
met het dsPIC ontwerp kon worden bereikt. De Sowter transformator kwam te vervallen
evenals de 36V voeding voor de driver. In plaats daarvan kwam een gewone 30
VA audiomodule van ILP (HY2001) waarmee rechtstreeks de driver wordt uitgestuurd.
Rekening houdend met het onderzoek van F.Fransson, gepubliceerd
in 1966, hielden we er ook hier terdege rekening mee dat de karakteristieke
formant in de fagot-toon rond 500Hz niet is toe te schrijven aan resonanties
van het eigenlijke instrument, maar geheel en al voor rekening komt van de werking
van het dubbel riet. Die formant werd dan ook in het excitatiesignaal toegevoegd.
Pas wanneer deze automaat wordt geaktiveerd in de kontekst van
het Logos Robotorkest, waarbinnen hij vanuit
een veelheid aan diverse sensoren en via doelspecifieke software kan worden
aangestuurd, wordt hij een heuse robot. Daarin ligt ook zijn bestemming.
Construction & Research Diary:
- 15.02.2009: Start of our search for a second hand bassoon.
- 23.02.2009: Two offers for bassoons traced. Need to be further examined.
Sebastian Bradt can do this for us, since he has some formal training in bassoon
- 24.02.2009: Sowter transformer, custom made after our specifications, delivered.
- 26.02.2009: I had a dream about the bassoon robot...
- 01.03.2009: Circuitry worked out.
- 03.03.2009: Sebastian Bradt went out to examine and test out two bassoons
we could purchase.
- 13.03.2009: The bassoon is selected and ordered... It ought to be quite
a good instrument.
- 18.03.2009: The bassoon, an Artla, has arrived from Blazers and Blazers.
- 19.03.2009: Fingering table worked out by Sebastian Bradt.
- 15.05.2009: measurements on the custom made Sowter transformer.
- 09.12.2009: Design drawings.
- 04.06.2010: Further research into impedance convertors to mimic double reeds.
- 31.01.2011: Construction of a first prototype of an impedance convertor
on the lathe. It connects to the original crook of the bassoon, and is made
to fit the Mc Crypt horn driver, type HT202C.
- 01.02.2011: First designs for the structure. Tentative construction and
mounting of solenoid valve for note 34 on the body of the bassoon bell using
the existing holes in the wood left after removal of the original levers.
For note 34 all solenoids will be inactive and the instrument sounds in its
full length. Opening of this valve (bit0) with all other valves closed, results
in note 33 sounding.
- 02.02.2011: construction of a valve for the second tone hole, note 36 (Low
- 03.02.2011: definitive mounting of the valve on the bell part, using Loctite
premium copper silicone (nr.5920). Further construction of seatings for all
5 valves on the low part of the bassoon (notes 36 to 40).
- 04.02.2011: definitive mounting of all valves on the low part. We could
play already notes 32 to 40 now... Design of the vertical mounting structure.
35mm hole drilled in a square piece of AISI 316 stainless steel to hold the
motor driver. Welded onto a piece of T profile 40 x 40. Length from center
of the hole to the tangent of the groundplane resting the bassoon: 883mm.
First presentation of parts, clamped to the welding table, to get a sight
on the mounting problems.
- 05.02.2011: Further design of the basic structure. Stability study. Movement
will be hard to implement... We decided to give this robot a touch of an android.
It should get blue eyes in the head, and breasts will give it a feminine gender.
- 06.02.2011: TIG welding works: mounting base instrument. Holding bars. Design
of seating structure for frontal valves.
- 07.02.2011: Start construction of the 3-valve assembly for the high notes,
- 08.02.2011: Finish of the 3-valve assembly automating the left hand fingers.
Mounting on the bassoon with copper silicone and four woodscrews.
- 09.02.2011: 10th valve assembled and mounted. This is the second highest
note. It seems we can drop at least 3 valves from the automation: 2 trills
and the octave valve, since those can be implemented differently. Note that
all valve saddles are secured to the bassoon body with stainless steel platescrews
3.5 mm diameter and 6 mm length. The sharp point of these screws was cut off,
such that the screws cannot protrude in the internal bore of the instrument.
Predrilling to a depth of 4.5 mm was performed by hand using a 2mm drill.
11th valve, with a 10mm pad prepared, assembled and mounted. Construction
of an experimental tubular pull type solenoid with a pad, this anticipating
on the problem of lack of space that we might encounter further on during
- 10.02.2011: Circuit overview worked out. Start construction of valve #12,
this requires a special 10mm pad.
- 12.02.2011: Valve #12 mounted. Start construction of valve #13.
All chassis parts made to seat the valves on the bassoon are made of thin
(0.6mm) stainless steel plate.
- 13.02.2011: Mounting of valve #13, on the low end of the bassoon, together
with valve #14. This means we are about halfway with the valve automation
- 14.02.2011: Design further worked out. No workshop activity today. Academic
duties at hand...
- 18.02.2011: Further work on valve #15. Mounting and finishing done. Start
work on the seat for valve #16, bottom of instrument, backside. This one has
a 21mm pad and covers a weird looking double hole, one hole looks like a rounded
rectangular slot, the other is a tiny hole.
- 19.02.2011: Finishing of the 16th valve. Design of the valves for the frontal
side of the bottom part. Valve #17 mounted, lowest one on the bottom part
frontal side. If we do
the minimum required, there are only six valves to be done now... we are counting
down. Power One 12V power supply module ordered from Farnell. This should
be the power supply for the valves and optional lights. Current rating: 5.1A
- 20.02.2011: Assembly of a three-valve set to automate the right hand fingerholes.
We make this as a single unit on a carrier plate of somewhat thicker stainless
steel. Adjustment of the middle valve will be quite tricky. All valves on
the lower joint are now mounted. Adjustments are still required. Twentytwo
valves done sofar. Of the 27 valves, 3 are only needed for trills and since
they are closed at rest, we can leave them on the instrument and we do not
have to automate them. One tiny hole is only used for overblowing, its the
hole on the crook. We can go without this one. The tiny hole below this one
seems not essential, but we have to further examine this. In case we can dismiss
it, we are done with the valves...
- 21.02.2011: Some puzzle solving... what's the order of the valves now? Is
this correct? Stainless
steel ordered from Demar-Lux as required for the construction of the trolley.
Problem of the pivoting point for the movement studied.
- 22.02.2010: Further study and experiments on the implementation of the movement.
It appears not to be such an easy matter taking into account the need for
smooth movement and the quite high forces involved. If we are to use a DC
motor, it should have at least a 1:60 slowdown gear. A model XYD-15B by Currie
Technologies Inc. (24V, 135W) seems adequate, though it will need a hefty
10A power supply.
- 23.02.2010: Construction of the 12V power supply and valve steering board
- 27.02.2011: Start implementation of <Fa> under GMT, so that as soon
as we have hardware components ready, we can also test them properly.
- 01.03.2011: Consulting session with Bernard De Graef, a professional bassoonist.
Bending of a dented wheel segment, module size 1.5, to radius 170mm.
- 02.03.2011: Order for dented wheels placed at MEA. Core hole drills purchased.
New consulting session with Bernard De Graef. Figuring out the exact valve
combinations from the usual fingerings was not such a straightforward matter.
Detailed scale 1:1 construction drawings started.
- 03.03.2011: Test setup to measure movement and motor force/speed involved.
- 04.03.2011: Assembly of the motor and worm-gear parts on a pivoting chassis.
Axle size for the activation pivot: 16mm. To overcome small irregularities
in the dented circle for the bassoon assembly drive, we plan to use a heavy
spring to hold the wormwheel drive against the dents. This mechanism also
allows easy release of the assembly.
- 05.03.2011: Motor silencing study. Welding works on the lowest part of the
bassoon craddle. Next thing to do: precision welding of the dented segment
on the craddle. If we do not get the delivery of stainless steel from Demar
Lux soon, then we will have to cope with a serious delay in the project, as
the next step is the construction of the chariot.
- 06.03.2011: Precision welding work of the dented wheel segment. We made
a special wheel compass to get this done with better than 0.5mm precision.
The method used can
be read from the pictures.
- 07.03.2011: Technical drawings.
- 08.03.2011: Backwheel specified and ordered from Blickle.
- 09.03.2011: Construction for the transmission mechanics worked out. M16
clamping handle ordered from Fabory, cat. nr. 56958.160.027
- 14.03.2011: Waiting for deliveries...
- 15.03.2011: Fresh stainless steel came flowing in. Chassis parts for the
bassoon cradle cut out.
- 16.03.2011: Tedious steel bending work on 10 mm thick stainless steel. Electrode
welding works using stainless steel electrodes, since the material is very
thick this goes a lot faster than the TIG welding we used sofar on this material.
Final strength is also much better, but this is not a major concern here.
- 17.03.2011: Finishing of the bending work and welding of the main chassis
structure. Outer chassis width fixed to 360 mm, length 850 mm.
- 18.03.2011: Steel cut out for the pivoting motor assembly for the movement.
- 19.03.2011: Extra bassoon holder welded to secure the upper part of the
bassoon in place. First tentative and experimental assembly of the mechanical
parts. Confirming the exact positions as drawn in the designs. Tentative placement
of all the electronic circuit components.
- 20.03.2011: All mechanical parts welded in place. First movement test with
the motor powered up. Seems to work fine. Bottom plate cut out for the backside.
This plate carries the power supply and the microcontroller board for the
valves as well as the midihub board and the backside wheel. Wheel axis prepared
and turned with endings for omega rings or circlips on the lathe.
- 21.03.2011: Further design work. Antique mA meter digged up for power monitoring
display: full scale 1.2mA, 10.7 Ohms resistance.. First delivery of ordered
mechanical components from MEA. Back chassis welded together and mounted in
place. This holds the Sowter transformer, the three PIC processor boards and
the valve power supply.
- 22.03.2011: Chassis parts for power meter cut out. Design of a steering
handle. Mounting of a frontal light: yellow 3W LED spot.
- 23.03.2011: Power supply parts ordered from Farnell. The Blickle wheel will
only flow in next week.
- 24.03.2011: Farnell order came in. Transformer (Myrra, 9V/10VA) for the
5V power, placement under the mains entry.
- 27.03.2011: Design work... Planning required.
- 03.04.2011: Steering handle cut out from 30x10 stainless steel. Angle 60
- 04.04.2011: Interview and photo session with Fa being under construction
for 'De Ingenieur', a dutch engineering magazine.
- 05.04.2011: Steering handle welded on the main chassis. Support welded also
for the Penny & Giles tilt sensor.
- 07.04.2011: Some building 'secrets' revealed for Cobra TV...
- 08.04.2011: Finalisation of soldering works for the ds-PIC board. Sunday
we work on the first firmware version with Johannes Taelman... High side modulator
board soldered as a breadboard circuit. This becomes the new implementation
of the volume controller. Schematic drawing and board layout drawings updated.
Power transformer for the 5V supplies glued under the mains power socked with
- 09.04.2011: Hardware tests for the dsPIC cirtcuitry and the high side driver.
NDP6020 P-channel mosfet was a bad choice! Its maximum voltage is only 20V
and the gate shouldn't get more then 8V. We better change this for an IRF5210
(100V/ 19A, 150Watt)...
On the picture we see the dsPIC board as well as the high side driver board.
These boards stack in top of each other.
- 10.04.2011: Start soldering works on the midi-hub board. Firmware version
1.0 in the dsPIC programmed with Johannes Taelman. Controllers 1,7,17, 18,19
implemented. The wave lookup now is a sawtooth as in <Ob>. This is subject
to changes in a future implementation. Basic PWM frequency is at 100 kHz.
Tentative capacitor value over transformer primary: 47nF.
- 11.04.2011: Measurement and evaluation session on the dsPIC implementation.
IRF9540 P-channel mosfets ordered from Farnell. The circuit as we made it
does not switch fast enough; turn-on time is o.k., but turn off is way too
slow. It gives up at about 20 kHz. Thus either we have to find a way to make
the P-channel mosfet switch much faster, or we have to use an alternative
PWM source operating at a lower frequency than the 100 kHz we use on the dsPIC.
The board and its connections so made look like:
A linear regulator could also be an option. Initial test code for <Fa>
added in GMT. Midihub board component placement, soldering and wiring finished.
This board is now ready for programming. All mosfet's here are IRL640.
- 12.04.2011: Design of high side driver changed: BS170 replaced with VN88AFD,
drainresistor now 820 Ohm and 17V zenerdiode. This gives much faster switching
on the gate of the P-channel mosfet, but it's still too slow, giving up at
about 42kHz. We tried also using a 74LS56 divider to bring the PWM frequency
down, but this didn't work out, for the divider removed all PWM modulation
on its outputs. Finally we gave up on this one, and worked out an analog alternative
using an LT1038 variable power regulator steered with a Silonex optor component.
This seems to work very well with residual PWM modulation completety filtered
out. The problem with this circuit however is that it uses now obsolete parts...
the LT1038, rated for 10A current.
- 13.04.2011: current limiting resistor in series with the Optor LED increased
to 18k: this gives an optimal control range. It's even more or less logarithmic!
Welding works on <Fa> demonstrated for Cobra television. Burn in tests
on the volume control design under load conditions.
- 14.04.2011: There is an alternative for the LT1038, with some limitations
however: the LT1083 can be used without circuit modifications but the input
voltage should be kept smaller than 30 V whilst maximum current is only 7.5
A. Finishing of the complete dsPIC module with the new high side driver.Construction
of a mounting plate in yellow massive polystyrene. Mounting of the backwheels
on the chassis, using M10 bolts and nuts.
- 15.04.2011: Start welding works on the underchassis structure. This is to
hold the power supplies and rectifier circuitry. We fall without Argon welding
gas... Murphy being the way he is, this happens on a friday evening such that
we have to spend a weekend without Argon gas.
- 16.04.2011: Further work on the mechanical aspects and construction of the
power supply carrier plate. This will be completely demountable if required.
- 17.04.2011: Continuing mounting works of power supply components. Design
of LED lighting. Sofar we provide in 4 LED spots, two pointing to the frontal
ground, two towards the bassoon, frontal. Together with the two eye-LED's,
this makes six, the maximum our hub board can accomodate. For the power supply
for the motor, we use an Erea transformer with two 12V windings, connected
in series. As a regulator for this we recycled an old board used in Harma
and designed for 15A.
For the compression horn driver we use a 63W toroidal with 2x22V secondary.
This will give us 31V unstabilised measured over the 10mF smoothing capacitor.
Stabilisation is probably not required here. We will have to find out. Placement
of components checked with mechanical requirements with regard to freedom
of movement with the bassoon mounted in its cradle.
- 18.04.2011: New 300 Bar bottle with Argon gas ordered from l'Air Liquide.
Wiring lay out.
- 19.04.2011: Argon gas came flowing in... welding works on lower chassis
finished. Power wiring, including the large switch in front, finished and
tested. Many of the Weidmueller connectors can be wired now.Memo
note: wires to power meter to be added!
- 20.04.2011: Wiring weidmueller connectors to the midihub and the dsPIC board
finished. Assembly works filmed for MIM documentary by Maarten Quanten. Spoke
wheels mounted. Equilibrium tests with the basson mounted. Start coding firmware
for the midihub board. The sensor need adjustment for a precize vertical position.
There must be a wiring bug in the dsPic board since we measure 24V on the
SMPS power module output where it ought to be 15V. No smoke stacks however...
- 21.04.2011: Two wrongly polarized LED's replaced on Hub board. Firmware
version 1.0 uploaded. On the dsPIC board assembly we forgot some ground connection
and forgot to cut a copper trace. Repaired now. All voltages o.k., both PIC's
are booting normally. Motor makes the bassoon oscilate around its vertical
position, but that was to be expected, as we started of with the code developed
for <Ob>. Preliminary pictures made for publication in CMJ.
- 22.04.2011: Sowter transformer mounted in place. Soldering work on the valve
- 23.04.2011: Writing of the firmware for the 18F4620 microcontroller steering
the valves. Firmware version 1.0 ready for testing and evaluation. Controller
66, 100, 101,102,103, 123 implemented. Fingered vibrato to be done.
- 24.04.2011: Implementation for fingered vibrato added in the 18F4620 firmware.
This version, still version 1.0, flashed in the PIC. We need empirical data
with regard to which valves to use for vibrato. As for now, we just used the
wet finger method. All valves wired. The lookup
table is documented in an odt file, together with the wiring and the mapping
for the PIC controller. In principle <Fa> can now play its first tentative
notes... In view of transportation, the top part of the bassoon was wired
with small connectors such that it can be taken off for ease of transportation
in trucks with height limitations. Start coding of test code in the GMT context.
- 25.04.2011: <Fa> plays its very first scales... Carefull adjustment
of valve seatings required. Motor controller goes into overload condition.
Fingering code seems working, but auto-release must still have a bug in the
firmware. Lookup table for fingerings in HTML
format added. Valve 20 is not mounted yet and seems not even required
in our implementation.
- 26.04.2011: Auto-release is now functioning fine. <Fa> demonstrated
for Kristof Lauwers, Helen White, Sebastian Bradt and Xavier Verhelst. We
have to revise the dsPIC code such as to put more energy in the low spectral
components. Trapeziodal wave seems better than triangular as we have it now.
Tuning checked: CC20 = 22 gives A=442Hz. Firmware for the midihub with the
movement control code revised. Blue LED lamp assemblies mounted as eyes and
on the backside of the breasts. Lite 5 seems not working, must be a bug in
the firmwire or pin mapping. Confirmed: should have been mapped on PortC.0,
- 27.04.2011: Power meter wired. Transformer wires shortened and connector
mounted and soldered on transformer chassis. Implementation of fingered vibrato
in the firmware.
- 28.04.2011: Further work on the valve PIC firmware. Some nasty bugs show
up... why is our timer mechanism blocking and halted at times?
- 29.04.2011: Further work on the valve PIC firmware: fingered vibrato implementation
- 30.04.2011: Finally got the fingered vibrato to work, using timer3 on the
18F4620. Now firmware version 1.4
- 01.05.2011: Postscaler added in timer3 interrupt service routine such as
to improve range of vibrato speed. Valve-PIC firmware version 1.5. This is
now working to perfection. Firmware for the hub-PIC improved: here we use
timer3 as a sampling clock for the position sensor. This firmware is now at
version 1.4. Motor tuning still left to be done. Working session on the dsPIC
firmware with Johannes Taelman. Lookup tables (8 x 32 16-bit entries (256
words) for a full period) changed to get a more trapezoidal wave. Last table
caused smoke stacks from the mosfets though. 7667 driver IC replaced. Mosfets
do o.k. on the workbench, but still not working in the circuit...
- 02.05.2011: Motor driver unit has failed... This was a Mc CRYPT horn driver
type HT202C, titanium diaphragm, 8 Ohm, 50W rms, 13/4" Kapton Bobbin
and flat copper-clad aluminium wire voice coil. 41 Oz Strontium Magnet. [Conrad
order nr. 452-055-06 & 2-986-954]. Looking for alternatives. Must be >
100W, 8 or 16 Ohm impedance and frequency range starting at 200 Hz. New
capilary impedance converter turned on the lathe to fit a Padu 100W driver.
(inner diameter 20mm). When we try it out, the power supply goes in overflow
and gets very hot. The high side driver goes into thermal protection and switches
off. Since things work -after cooling down- when we use only a single mosfet
at a time over half of the transformer primary winding, we conclude that the
driver is not properly working in push pull: the signals cannot be 180 degrees
shifted in phase as they should. Hence, the bug must be in the dsPIC code.
- 03.05.2011: Further measurements and evaluation. We have to investigate
further into the attack of the sound, the build up of the resonance in the
tube. The slope needs control, but only after a previous explicit note-off,
otherwize we get in trouble with pure legato playing.
- 12.05.2011: <Fa> descended from the welding table in the workshop...
Start composition of 'Early Birds': Namuda Study #15
- 14.05.2011: Soft silicone membrane inserted in bassoon clamp. Overblow tonehole
closed with silicon. Code for 'Early Birds' tested and rehearsed.
- 15.05.2011: First rehearsal for 'Early Birds' with Dominica Eyckmans.
- 16.05.2011: DVD video recording made with Laura Maes for CMJ article.
- 19.05.2011: Premiere of Namuda
Study #15, for viola and <Fa> robot: 'Early Birds'
- 21.05.2011: New programming session for the PIC on the midihub board: motor
control. Version 1.5 now.
- 22.05.2011: Debug session with Johannes Taelman. dsPIC phase seems o.k.,
but as windings are switched or capacitor values from 1 uF on are switched
across the windings, the circuit gives up. Maybe with a burn out of the ICL7667
driver. With both phases working, the sound quality is more bassy, but less
bassoon-like. Further research into the code of the hub (motor and lights):
the irregularities in the periodic timers must be a subtle bug. Primary fuse
on motor power transformer molten, so there must be high surges here.
- 23.05.2011: Hardware check of the dsPIC board reveals: 7667 driver burned
out as well as both power mosfets... a complete fusion. Lesson: we should
never switch transformer winding load with the power on! Irregularity bug
in periodic timers solved. Power mosfets and 7667 chip replaced. Firmware
for the hub board upgraded to 1.6 Motor coding still under development.
- 24.05.2011: Valve control firmware upgraded: now any valve can be used for
fingered vibrato. Lookup table for the lowest octave updated and improved.
- 25.05.2011: Fingered vibrato implementation optimized. Lookups modified
for the entire compass. Valve-Pic version 1.6 now.
- 28.05.2011: sketches for a new pressure driver board.
- 30.05.2011: Market search for better compression drivers.
- 09.06.2011: Output transformer secondary rewired for 16 Ohm operation to
match the Padu driver better. VU meter connected over 8 Ohms tap, to give
- 18.11.2011: Glissando playing now fully implemented under GMT
- 20.01.2012: Bug killed in the firmware for the valve control PIC: TRISE.4
must be cleared in order to make portD work. Now version 1.7
- 11.07.2012: <Fa> made its first trip to the Ghent Townhall. On the
return tranport the bassoon-assembly shaked loose from the dented wheel. No
severe damage, but we had to readjust three valves on the front of the instrument.
Now it works fine again.
- 09.09.2012: The positive experiences gained in the development of our <Klar>
robot, lead us to consider the application of an ARM processor (32 bits) for
the compression driver. We prepared already such a board for this experiment.
- 18.09.2012: Start construction of the required chassis parts to hold the
newly designed compressor driver. This will replace the dsPIC board be now
have. As a consequence, the midi implementation table as well as the defaults
will have to be reviewed. We will not implement the changes before september
23th however, as <Fa>, as is, has an important role in 'Slones' the
wind octet to be premiered in Antwerp at Muhka...
- 23.09.2012: Premiere of 'Slones' in Antwerp. <Fa> came back with some
- 24.09.2012: Removal of the original compressor driver circuit as well as
the Sowter transformer. Seems we also have to improve the way the bassoon
is held in place. It shakes too much during transportation in a truck.
- 25.09.2012: Wiring of the new driver circuitry. This will be <Fa>
- 28.09.2012: Mounting of the bassoon in the stand improved.
- 29.09.2012: Firmware programming session for the 32-bit ARM processor with
Johannes Taelman. This will modify the entire midi implementation table. Documentation
(this webpage...) updated accordingly. Circuit drawings redrawn to reflect
all changes. GMT software adapted to render testing of the newly implemented
Sowter transformer removed from the chassis.
- 30.09.2012: Version 1.1 made archival. Testing and evaluation for version
- 02.10.2012: Power meter circuit recalculated and calibrated for correct
- 19.05.2014: The movement mechanism seems to fail. The Trident motor controller
gave up and might have been underdimensioned. So we started designing a new
power driver, using a 150W op amp (LM12) from National Electronics.
- 23.05.2014: Construction of the analog power operational amplifier required
to improve the movement.
- 26.09.2016: <Fa> transported to Berlin for participation in the 'Wir
sind die Roboter' Festival.
- 02.10.2016: <Fa> returned safely from its appearence in Berlin.
- 03.10.2016: <Fa> thoroughly checked. The light mapped on note1 (inside
chassis, yellow spotlight) is not working. Probably just something with a
loose lamp socket. Otherwise, <Fa> found to be in perfect working condition
except for the movement that still needs a redesign of the motor controller.
- 26.10.2016: Design of different circuit possibilities for the motor and
the movement. A DCM motor controller and a cw/cww relay is one option, a 24EP128MC202
16-bit pic with a full H-bridge another one.
- 27.10.2016: Circuit with a full H-bridge and transformer gate-drive worked
circuit easily fits on a eurocard PCB.
- 28.10.2016: <Fa> on the road to Brugge for the 'Iedereen Klassiek'
event in Concertgebouw. An alternative motor control could be this: Here
we could use a United Automation Ltd. DCM24-40 motor/heat controller. This
module should be capable of delivering up to 40 A. The PWM frequency is rather
low (ca. 370Hz) and could lead to audible artefacts. Here is the data
- 30.10.2016: <Fa> set up again in the orchestra and found fully o.k.
- 01.11.2016: Two new PCB's designed and etched. One for a 24V/6A power supply
and one for a new microprocessor board for motor control. Power supply board
finished: This is the schematic:
And, this is the PCB: It
uses now largely obsolete voltage regulators in a TO3 packages, as we still
did have quite a few in stock. Each L7824CT can handle 1.5 A, so we get 6
A by parallelling them. The circuit fits nicely on a single Eurocard board.
We keep the original Erea transformer. Here is the assembled board: The
PCB for the newly designed motor control board looks like:
Soldering of this board will be done tomorrow... Both boards will be soldered
leadfree, for a change...
- 02.11.2016: Drilling and soldering of the motor control board. The SPDT
direction control relays are STE 02-SH-112D (Farnell order code 189-1809).
Coil: 12V, contact rating: 16A. Here is the finished board:
- 03.11.2016: Writing firmware for the motor control board.
- 04.11.2016: Controller 67 implemented in the firmware such that automated
movement in function of the average pitches played can be realized easily.
When no notes are played, the robot will return to the fully reclined position.
- 05.11.2016: Testing of the motor board with a sensor and a spare 24 V motor.
- 06.11.2016: Further development of the firmware and PID control.
- 07.11.2016: Start mounting of the new boards into the <Fa> robot.
We replace the dented drive wheel with a wider one to have a better grip and
hold the bassoon on place. Also we blocked the drive mechanism in position
with an M4 bolt through the pivoting mechanism.
- 08.11.2016: Rewiring of the <Fa> robot finished. First testing. After
reversing motor polarity, everything seems to work, apart from setting correct
parameters. There is a big problem though: the PWM frequency is very prominent
and audible from the motor windings... This is due to the DCM motor controller.
- 09.11.2016: Further work on optimalisation of motor and movement parameters.
- 10.11.2016: We got the PID parameters reasonably right now. Overshoot is
minimal. We have to watch out for motor stalling conditions, as the current
rises up to very high values, possibly exceeding the maximum current (6A)
the power supply can provide.
- 26.07.2017: <Fa> parts revised for our 3th Symphony (Die Jahreszeiten)
as well as for Fall'95-Version 6, to go on the road to Liepaja (Latvija).
- 01.08.2017: <Fa> left for Liepaja... 2000 km away.
- 09.08.2017: <Fa> returned safely from its trip to Liepaja.
- 22.11.2017: <Fa> joined the party at euRobotics in Brussels. On return
one of the solenoids was found completely loose. Two M3 nuts replaced and
all nuts now secured with red Loctite lacquer.
- 17.02.2019: <Fa> on the road to Sint-Niklaas for 3 concerts at 'Passage
VI'. Returned safely.
- 02.05.2019: Checked and the stainless steel underplate found to have loose
M6 bolts and nuts. Fixed before its trip to Koeln.
- 06.05.2019: <Fa> returned from Koeln.
- 01.07.2019: <Fa> gets a crucial role in our orchestration of Le Sacre
du Printemps. Performances on july 23, 24 and 25th of july.
- 29.07.2019: <Fa> joined the orchestra on the Tomorrowland dance festival
en returned safely. Some cleanup required.
- 30.07.2019: Traces of rust removed from the regular steel parts. It must
have been very wet at Tomorrowland.
- 09.03.2020: Considering to automate the blue eyes, in the same way as done
on <Flut> and <So>, version 3. This involves minor changes, and
a full upgrade, of the firmware for the hub board. Here
is the new source code.
- 12.04.2021: Due to an overload, the compression driver was found to be burned
out. So we replaced it with a new Padu driver, 100W - 16Ohm, as we still had
one in stock. Maybe we should reduce the volume setting a bit.
- 29.04.2021: The streaming session on FB (here
is a link) caused us a ban on Facebook, due to the dutch word for the
bassoon: fagot... a taboo word in English apparently.
- 27.09.2021: After playing uninterrupted for 25 days in the SMAK museum,
<Fa> returned to the robot orchestra in perfect condition.
- improving sound balance between low and high notes.
- carefull check of the valves for leaks, replacing pads with more reflective
- empirical verification of the valves to use for fingered vibrato.
Last update: 2021-09-27
by Godfried-Willem Raes
The following information is not intended for the general public nor for composers
wanting to make use of our <Fa> robot in their compositions or orchestrations
for the robot orchestra, but is essential for maintenance and servicing of the
robot by our collaborators. It also might be usefull for people that want to
undertake similar projects. Feedback is mostly welcomed.
Technical drawings, specs and
- +5 V DC - 250 mA : (Logic and microcontrollers), Myrra 9V / 10VA transformer
coupled to the on board regulators situated on the midihub board and the valve
- +12 V DC - 5.1 A : (Solenoids & lights) Linear power supply module Power
One type HN12-5.1A. Adjustable from 10.3 V to 13.5 V. Used for the solenoids
and the lights. Maximum power for the solenoids is 17 x 150 mA = 4A. The solenoids
have a cold resistance of 80 Ohms.
- + 24 V DC - 6.6 A : Movement motor power supply (2016)
- -26 V/+26 V - 30 VA power supply for the HY2001 driver amplifier (Version
Wiring & circuit details midihub board:
Firmware for this controller
Circuit details solenoid driver board: (circuit drawing can be enlarged)
Firmware for this controller
Mechanical construction drawings and welding plan:
- Movement mechanics:
- All chassis parts made of AISI 304 stainless steel. Welding was performed
mostly using the manual TIG process with intermittent cooling using compressed
air. The parts made from 10 mm thick stainless steel were welded with special
stainless steel electrodes.
Mounted now: Padu horn driver 100W / 16 Ohm.
Other types to investigate or to consider:
|| PA type
||100- 3700 Hz
60W @ 300Hz
2" voice coil
made in Texas (USA)
10W @ 50Hz
used for <So>, V3.
16 Ohm or
||180 - 6000 Hz
70W @ 800Hz
100W @ 1200Hz
| 16 Ohm
|| 500Hz- 20kHz
||4W @ 50Hz
||150W @ 500Hz
|| 400 - 9000 Hz
made in Brasil
Volume displacement: 0.5 l
15W @ 60Hz
used for<Hunt>, V1.0
|| 25W rms
|| 8 Ohm
Kapton Bobbin and flat copper-clad aluminium
wire voice coil. 41 Oz Strontium Magnet. [Conrad order nr. 452-055-06
Sold as 100W power!
made in USA
This type burned out during the very first tests
||100Hz - 10kHz
||made in China
in use now on <Fa>
also used in : Heli, Bono, Autosax, Klar, Horny,
compression driver dismantled from horn
made in Taiwan
tried in Korn
||compression driver dismantled from
||used in <Korn>
||made in Italy
||used in <Ob>
Currie Technologies Inc., model XYD-15B, 24V DC, rated speed 3000 rpm, rated
current 10A, output power 135Watt. At no load and operated on 24V, the motor
draws 0.5 A. We bought one from All Electronics, cat# DCM-1506, ref. 1353583.
It's a type of motor used for electric bicycles and small scooters. A more
silent motor would be a better choice here. Datasheet.
Motor Controller: Trident
Engineering. (A Maxon 4-Q controller is also possible, but much more expensive)
[removed november 2016, as its power handling capacity was too low]
- Supply voltage: 10V to 35V.
- Maximum output voltage: +/- 27.5V dc or 6V below I/PV
- Maximum current output: +/- 2.urrent limit: adjustable
125mA to 2.2A. Short circuit protection is inherent in current limit.
- Thermal protection: trips when the base plate temperature
exceeds 50 degrees Celcius and LED lights up. To reset, the power has to be
- Analog voltage control: Only possible with an isolated
power supply. The reference input voltage must not exceed half of the controllers
supply voltage, i.e. with a controller supply of 24V, the reference input
voltage range is 0-12V.
Motor Controller 2016: DCM24-40, made by United Automation Ltd.
- Supply voltage: 24 V DC
- Maximum output current: 40 A
- Control voltage: 0 - 5 V DC
- circuit for this PCB:
Penny & Giles tilt sensor: Datasheet
Firmware for the motor controller: (Proton Compiler to be used)
Builder: Artla , foreign imported by Boosey & Hawkes, London.
Made in France. The instrument must have been made after 1981, since in that
year Buffet-Crampon came in the hands of Boosey & Hawkes. The serial number
of the instrument is 356. The instrument was in perfect shape before we started
Download high resolution pictures of this robot:
- Robody pictures with <Fa>
Baines, Anthony, 'Woodwind instruments and their history',
ed. Faber and Faber Ltd., London, 1977 (1957). ISBN 0 571 08603 9
Bartolozzi, Bruno, 'New Sounds for Woodwind' , Oxford University
Press, London 1982 (1967), ISBN 019 318611-x
Benade, Arthur H., "Fundamentals of musical acoustics",
Dover Publications Inc., New York 1990 (1976). ISBN 0-486-26484-x
Fransson, F. "The source spectrum of double-reed wood-wind
instruments" In: STL-QPSR, vol7,nr.4, 1966, p.035-037 Weblink: http://www.speech.kth.se/qpsr
Raes, Godfried-Willem, "Expression
control in musical automates", 1977/2021,
Raes, Godfried-Willem, "Logos @ 50, het kloppend hart
van de avant-garde muziek in Vlaanderen", ed. Stichting Kunstboek, Oostkamp
Springer, George H., "Maintenance and Repait of Wind and
Percussion instruments", Boston, 1976, ISBN 0-205-05012-3
Smith, Bob H., "An Investigation of the Air Chamber of
Horn Type Loudspeakers", in: The Journal of the Acoustical Society of America
25, 305-312 (1953); https://doi.org/10.1121/1.1907038
Waterhouse, William, "Bassoon", entry in: The new
Grove Dictionary of Musical Instruments, ed. Stanley Sadie, MacMillan Press
Ltd., London, 1984. ISBN 0-333-37878-4
Weijers, Rembert, "Rieten ontwerpen en maken", Muziekuitgeverij
van Teeseling, Nijmegen, 1978