<HAT>


a hit any thing percussion robot

Godfried-Willem RAES

2009

[Nederlandstalige versie]

Robot: 'HAT'

The design of this musical robot started with a request from Aphex Twin. After some exchange of ideas, we agreed to undertake the task of designing a musical robot that could be used to strike just about anything. For technical and physical reasons however it is impossible to realize this in its full generality. The mass of the striking object always has to be in proportion to the mass as well as the magnitude of the spring-force behaviour of the object struck. Big objects require big beaters to obtain a big sound, put it simple words. Hence in our design we decided to foresee a variety of different beaters and mechanisms such that for a wide variety of objects, a suitable beater can be found in the robot. A strict condition for the robot to function properly is that the object struck should always be clamped ridgidly to the structure. If the struck object is allowed to move even slightly, precise control of the striking forces and hence of the musical dynamics, becomes unpredictable if not impossible. The largest beaters are driven by very large and heavy solenoids driving a bass-drum kind of mechanism. They can be used for objects such as gongs, bass drums, heavy metal plates etc. These mechanisms are mounted near the base of the robot on both the right and left sides. The traditional footstepplate disappeared altogether in our pedal design, where the solenoid pulls the chain driving the rotating beater mechanism directly.

Also on the bottom structure we mounted two rotary solenoids to be used for objects/instruments placed on the floor. Two 'hands' with four 'fingers' each are designed to make very fast rolls possible. These mechanisms are mounted on adjustable slides in the upper part of the robot. They are similar in function and operation to the beaters we designed for <Snar>, our snare drum playing robot.

Two sets of three beaters operate in a vertical plane. These use a similar technology as well as the same type of solenoids, as we designed in earlier robots such as <Xy> or <Tubi>.

Sixteen beaters (two sets of four and one set of eight) make use of modified relay solenoids. These can operate pretty fast and are very suitable for rolls. The tips of these beaters are made of exotic wood.

Two beaters, mounted on the underside of the robot make use of rotary solenoids and can be adjusted in position. They are meant to beat objects placed on the floor. When moving or transporting the robot, these mechanisms have to be brought in an upward position such as to avoid damage during handling and transportation.

Next to the beater mechanisms, we could not resist in providing also a shaking mechanism. This idea builds further on the experiences gained during the construction and use of our earlier <Thunderwood> (this one has wood chimes and a large thundersheet) and particularly the <Psch> robot. The last one uses only shaking mechanisms.

The chassis and troley for this robot was made of very sturdy steel in order to be free of own resonances and unwanted noises. The structure was designed such that the stand-off from ground level becomes 100mm, thus making it possible to have the robot hit objects arranged on the floor. The heavy duty wheel base is a welded construction made from ST42 steel, whereas for the upperpart stainless steel AISI304 or AISI316 is used.

The entire circuitry for this robot makes use of a few fast PIC controllers: One Microchip PIC 18F2525 and one Microchip PIC18F4620 - I/SP types. The timing resolution, essential to obtain a good velocity sensitivity, is extremely high (in the order of 20 microseconds). The circuits are visible in the robot assembly but protected with a transparant polycarbonate cover. To remove dust from the circuits, compressed air (2 Bar pressure is enough) should be used.

 

The robot as yet is still in the development and building phase, in as far as the details of the beater mechanisms are concerned. The final projection however is:

In order to conform with electrical safety regulations, the chassis is connected to mains ground. A grounded power cable should always be used.

Circuit Overview:


High Voltage pulse board:



Midi Mapping and Implementation:

 

The midi channel for <HAT> is 10 (0-15) or 11(1-16).

midi note object repetition rate   Voltage wiring PIC
36 left pedal     100V  
37 right pedal     100V  
38 left toes     100V  
39 right toes     100V  
40-41 shaker (alternate)     100V  
42-43 optional expansion -   100V  
48-51 left hand     50V  
52-55 right hand     50V  
56-58 vertical beater left     50V  
59-61 vertical beaters right     50V  
62-63 optional expansion -   50V  
72-75 upwards left     200V 18F2525
76-83 back beaters     200V 18F2525
84-87 upwards right     200V 18F2525
96 light left eye        
97 light right eye        
98 light frontal        
99 light frontal        
           
           

 

Midi note range: 36 - 87 ( see table) , velocity implemented . Lights have no velocity, just on/off.

Note Off commands are not required for the beaters.

Controller 66 is used to switch the solenoid power on or off.

Program Change: implemented to change to different user programmable velocity scalings and lookup tables

<HAT> responds to the midi all-notes-off command. (Controller 123)

Sysex: implemented for user programmable velocity scalings. Pincodes: hat1, hat2

Technical specifications:

Design, research and construction: dr.Godfried-Willem Raes (2009)

Collaborators on the construction of this robot:

Some pictures made during the construction, in chronological order:

with some 'anythings' mounted:

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Nederlands:

Robot: <HAT>

Dit is de eerste robot die we op bestelling ontwierpen en bouwden. De enige tot nu toe die niet wordt ingelijfd in het M&M orkest. De bestelling kwam van Aphex Twin, die ons aanvankelijk kontakteerde met de vraag of we niet bereid waren een van onze bestaande robots aan hem te verkopen... Maar, aangezien alle robotten deel uitmaken van het M&M robotorkest en ettelijke komposities in hun klinkend voortbestaan afhankelijk zijn van de volledige samenstelling van dit orkest, weigerden we op die vraag in te gaan.

Na heel wat over en weer praten en onderhandelen, stemden we er uiteindelijk mee in een speciale nieuwe robot te ontwerpen: eentje die allerhande objekten en instrumenten zou kunnen aanslaan en tot klinken brengen. Toen we goed en wel aan het ontwerp begonnen, bleek zo'n min of meer universele robot algauw onnoemelijk vele problemen met zich te brengen. Immers, algemeen gesteld moet de massa van het aangeslagen instrument (inklusief de veerkracht ervan) in verhouding staan tot die van de klopper. Een robot die zomaar op alles kan slaan is daarom alleen al ondenkbaar. Zelfs wie niet muzikaal technisch goed onderlegd is zal begrijpen dat je geen triangel kan aanslaan met een paukestok, zomin als je een bastrom tot klinken kan brengen met het metalen staafje waarmee de triangel aangeslagen wordt. Om die reden voorzagen we deze robot dan ook van een grote variatie aan kloppers en elektromagneten zodat voor eender welk objekt wel ergens een geschikt aanslagmechanisme kan gevonden worden. Dit neemt natuurlijk niet weg dat het noodzakelijk is om de afstand objekt-klopper al naar het geval heel nauwkeurig in te stellen en te optimaliseren.

Aangezien een gammele en rammelende konstruktie voor zo'n ontwerp volstrekt uit den boze is, ontwierpen we voor deze robot een gelast chassis uit uiterst stevig profielstaal en voorzagen we dit van een onverwoestbaar stevig wielstel. Daarbij werd voor een driewiel konstruktie geopteerd, omdat zoiets per definitie altijd stabiel staat. Zoals in vele van onze robots speelt ook hier weer de hoek van 60 graden een konstruktief zowel als estetisch belangrijke rol.

Voor het 'pedaal'-mechanisme vetrokken we van het tegenwoordig gangbare middels een ketting aangedreven tuig. Hiervan verwijderden we de treeplaat geheel en aktiveerden we het draaimechanisme rechtstreeks via een uiterst krachtige trekmagneet.

Tessituur:

 

Bouwdagboek:


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Last update: 2010-08-06 by Godfried-Willem Raes


Techical drawings construction:

Frontwheel welding diagram

Backside, photo-sketch:


Technical data sheet and maintenance instructions:

Power Supply circuit:

Note that the power supply carries dangerous voltages. Before servicing, switch off the robot and give it 10 minutes rest, to enable the hefty capacitors to discharge. The connections on the power supply module are laid out as follows:

Electromechanical parts:

finger solenoids, Marked BLP 44A 220 621 620, 8 MO213, Farnell order code 1207167, 12V @ 100% duty cycle. DC resistance 47 Ohm. Power rating: 3 Watt. Push type. Plunger weigth: 8.5g. Stroke: 12mm maximum. When operated on 24V, we obtain a power of 12W but duty cycle should be limited to 25%. Maximum current during the pulse than becomes 510mA. All threads for mounting are M3. Website of the manufacturer: http://www.blpcomp.com. (eight pieces used)

beater solenoids: Black Knight, 12 V @ 100% duty cycle.

Pedal solenoids: August Laukhuff, 24V, 1.4A @ 100% Duty cycle for 75N force, travel 20mm. Rdc = 17 Ohm. Laukhuff order number: 301010 (two pieces used)

Sideways solenoids: Laukhuff Tonventilmagnet 12/14V, Rdc = 30 Ohm, 470mA, 6 to 7.5 N force at duty cycle 100%. Laukhuff order number: 300900. (six pieces used)

Rotary solenoids: Lucas Ledex (now Saaia Burgess) type H-2711-033. Axle 4.7mm, device diameter: 35mm. Rotation angle: 45 degrees. These solenoids are extremely expensive! (two pieces used) If they need replacement, it would be better to use type L-2711-033(CW) and L-2712-033 (CCW). DC resistance: 75,3 Ohms, nominal 100% duty cycle voltage: 26V, at 50% duty: 37V, at 25% duty, 53V, at 10% duty 83V and at 5% duty cycle 118V.

Lights:

Top-lites: Paulmann, LED 50mm spotlights, 12V 1W. Beam angle: 24 degrees. Lifetime 50000h. Socket GU5.3 Light color temperature 6400-7000K (daylight).

Frontwheel-lites: LED 50mm spotlights, 12V 1W, Beam angle: 15 degrees. Socket GU5.3 - MR16. Lifetime 50000h. 240 Lux. Conrad order number: 570949.

Never replace these lights with different types! The lites are fixed in the flanges with silicone glue. They can only be removed with a sharp knive or a chivel. Before doing this, make sure the robot is unplugged and has been given enough time for the capacitors to fully discharge.