EL INSTINTO SOCIETAL

Robotic percussion systems are the most widely-built variety of musical robots. Many advances in robotic musicianship, robotic ethnomusicology, and musical robotic ensem- bles largely or exclusively feature percussion instruments. The abundance of robotic percussion instruments is likely due to their potential for mechatronic simplicity: unlike chordophones or aerophones, functional percussive effectors (for both ideophones and membranophones) can be built with few moving parts, allowing for workers to focus on compositional rather than engineering goals.

This subsection examines four key contemporary applications in which robotic percus- sion instruments are used: ensembles of robotic instruments, percussion robots as a means of furthering robotic musicianship, and mechatronic percussion systems in ki- netic sound sculpture. Common traits across each of these subdisciplines are examined, and a chronology of each is presented.

Robotic percussion instruments have long played a key role in many historical and contemporary examples of musical robotic ensembles. Pioneers Trimpin and Godfried- Willem Raes, discussed previously in Section 2.2.1, include percussion instruments in many of their sound sculptures and compositions. The Logos Foundation, for example, features at least 20 automatic drumming instruments in their Man and Machine robot orchestra [20]. Trimpin’s sculptural ensembles, of which many can be seen in [19], [21], and [22], often utilise mechatronic drumming apparatus: his worksJackBox and Laptop Percussion (detailed in [6]), for example, use solenoid-actuated drum beaters.

Many recent musical robotic ensembles consist either partially or completely of percus- sion instruments. As of 2004, Eric Singer’s League of Musical Urban Robotics (LEMUR) consisted largely of solenoid-actuated ideophones and membranophones [1]. According to Singer et al., these instruments...

“...provide composers with an immediacy of feedback, similar to composing on synthesizers. However, as opposed to synthesizers, physical instruments resonate, project and interact with sound spaces in richer, more complex ways. Clearly, they have a more commanding physical presence as well” [1].

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Many robotic ensembles formed after Singer’s LEMUR also make use of percussion instruments. Ensemble Robot2, a human/robot performance troupe founded by Chris- tine Southworth and Leila Hanson whose first performance was in 2005, extensively use solenoid-based percussion systems. Brighton-based artist Sarah Angliss performs with an array of bell-playing and anthropomorphic robots3. Both Felix Thorn, creater of Fe- lix’s Machines4, and Roger Aixut et al., founders of the Cabo San Roque experimental instrument collective and creators of The Mechanical Orchestra of Fran¸ca Xica5, make use of solenoid-based percussion systems in their robotic sculptures and performance instruments. Most of these ensembles, further described in [23], utilise relatively simple mechatronic systems: actuators with few degrees of freedom are employed, and technical simplicity is favoured over parametric density. Chapter 5 presents a number of these systems, comparing them with more parametrically expressive approaches.

Other recent notable musical robotic ensembles include Carnegie Mellon University’s RobOrchestra, directed by Dan Curhan, Nick Yulman’s percussion ensemble, and Ajay Kapur and Michael Darling’s KarmetiK Machine Orchestra. RobOrchestra includes a wide array of instruments, many of which use solenoid actuators for percussive ef- fects6. Yulman’s Index Boogie7 is an assortment of mechatronic percussion instruments. The KarmetiK Machine Orchestra [6], consists of an ensemble of human musicians and robotic percussion instruments. These instruments are outlined in [6] and further de- tailed in [24], [25], and [26]. While some of these ensembles feature novel approaches to drum effector design, most use solenoid-based drum beaters with limited degrees of freedom.

The reasons for the abundance of percussion instruments in ensembles of musical robotics are likely twofold. Firstly, mechatronic instruments excel at many of what Singer de- scribes as the key reasons to explore robotic music: “. . . robotic instruments can play in ways that humans can’t or generally don’t play. Some of these capabilities include speed, pitch and expression granularity, complex polyrhythms and extended duration playing” [1]. These reasons can be explored to some degree with even the simplest, least “expressive” mechatronic instrument. Secondly, composers and inventors seeking

2_{http://www.ensemblerobot.com/ (retrieved September 2, 2013)} 3_{http://www.sarahangliss.com/ (retrieved September 2, 2013)} 4_{http://www.felixsmachines.com/ (retrieved September 2, 2013)} 5_{http://www.cabosanroque.com/ (retrieved September 2, 2013)}

6_{http://roboticsclub.org/projects/roborchestra/overview (retrieved September 2, 2013)} 7_{http://nysoundworks.org/ (retrieved September 2, 2013)}

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to create large arrays of robotic instruments likely turn to often-simple robotic percus- sion apparatus as a rapid means by which to explore masses of instruments on stage or in the gallery. Such simple drum beaters can be inexpensively duplicated en masse in a manner difficult for expensive parametrically-rich drum players (though Nudge, de- scribed in Chapter 5, is designed with simplicity and low parts-count as a goal, allowing for easier duplication than similar instruments).

Rather than create ensembles of percussion instruments, some workers use robotic drum- ming systems as research tools to further what roboticist Gil Weinberg calls “robotic musicianship” [27]. It is in this subdiscipline of musical robotic percussion where most novel work on expressive drum players appears to be emerging. While both Trimpin and Godfried-Willem Raes have long explored novel means of extending robotic percussion techniques, Weinberg himself is an early and important contributor to the field. His 2006 work, coauthored with Scott Driscoll, “Toward Robotic Musicianship” [27] introduces a drumming system with added degrees of freedom. Weinberg’s robotic algorithms take advantage of his robots’ added degrees of freedom, allowing them to extend their expres- sivity [28]. Other workers who turn to novel approaches to explore robotic musicianship are the creators of the Expressive Machines8ensemble, who have developed a snare drum fitted with a large number of beaters, allowing for composers to selectively strike various regions of the drum head. More recently, Jun Kato [29] and Alyssa Batula, et al. [30] have explored using novel software techniques and control schemes to allow for simpler and more reliable percussion systems. The intentions of these workers on percussion- based “robotic musicianship” appear most similar to those espoused in this document: enhanced expressivity through increased mechatronic and software sophistication. Quite different from robotics researchers are those who use robotic percussion in kinetic sound sculpture. While many kinetic percussion sculptures, such as those of Zimoun9 (discussed further in [31]), Pe Lang10, Chris Kaczmarek11, and Dan Senn12, are arguably more electromechanical than robotic, some workers use the same technology developed for other subdisciplines of robotic percussion within their sound sculptures. Nicolas Bernier13, for example, uses solenoid-based striking systems to actuate tuning forks in

8_{http://www.expressivemachines.com/ (retrieved September 2, 2013)} 9_{http://www.zimoun.net/ (retrieved September 2, 2013)}

10_{http://www.pelang.ch/ (retrieved September 2, 2013)} 11_{http://chriskaczmarek.com/ (retrieved September 2, 2013)}

12_{http://www.dan-senn.com/index.html (retrieved September 2, 2013)} 13_{http://www.nicolasbernier.com/ (retrieved September 2, 2013)}

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his 2011 pieceFrequencies. Making use of augmented instruments, Lukas Flory, Alexan- dros Konstantaras, and Andreas Gartz use solenoid-based drum beaters to strike frame drums14. While such workers are perhaps less scholarly than many in the other subdisci- plines in their pursuit of expressive percussion instruments, the works produced by these artists often differ greatly from the popular “solenoid drum beater” paradigm discussed above. Because of this novelty, such percussive sound art can serve as inspiration to those seeking new methods of musical robot percussion expressivity.

Automated percussion is perhaps the most diverse of the subfields of musical robotics: its widespread application in ensembles, robotic ethnomusicology, kinetic sound sculp- ture, and robotic musicianship research applications is likely due in part to its simplicity when compared to the more mechatronically-complicated subfields of robotic chordo- phones and aerophones. While works such as [27] highlight innovations in more com- plicated drumming systems, many implementations opt for simplicity over expressivity: there exist opportunities for roboticists to greatly enhance the expressivity of robotic percussion through the use of feedback and additional degrees of freedom. Chapter 5 of this document presents examples of such new work in musical robotic percussion.