Towards an Automated Pan Flute Player

Transcription

1 Towards an Automated Pan Flute Player Kishan Kumar School of Engineering & Physics The University of the South Pacific Suva, Fiji Praneel Chand School of Engineering & Physics The University of the South Pacific Suva, Fiji Kishen Kumar School of Engineering & Physics The University of the South Pacific Suva, Fiji Dale A. Carnegie School of Engineering & Computer Science Victoria University of Wellington Wellington, New Zealand Abstract This paper outlines some of the design details of creating an automated Pan Flute player targeting the Solomon Island s Pan Flute in the Pacific Region. Hence, the system functionality will be discussed first through a block diagram. Then the design will be further elaborated through discussion of the hardware assembly and different system modules. Thereafter, the results with overview of the system implementation will be presented. Finally, implications of the automated pan flute player on the society and future improvements will be discussed. Keywords; pan flute; automation; robotics; frequency; music; I. INTRODUCTION Developing technology has achieved huge progress in the late years and most applications which were once fulfilled manually have now been robotized. Normal cases of such situations extend to unmanned air/ground vehicles [1] [2] and as of late automated musical players too [3]. Since the very beginning, music has been known to coexist with men. Music has impacted the course of history as well as the emotions of people through countless rhythms. To create this wonderful art, song writers and musicians have to endure the process of continuously writing, making and editing songs until perfected. Hence this routine can become monotonous and tiring. Proceeding onward, electromechanically created music improves the capability of producing tunes while disregarding human limits like weakness/fatigue from playing over long periods of time. This paper undertakes a creative approach to address the limitations of robotic automation applications of musical instruments in the Pacific. Thus the limitations in terms of sound quality and playing speed will be examined through the creation of an automated Pan Flute player. The conceptualization of mechatronics based musical instruments is not a unique thought, however few pan flutes have electromechanical players that deliver high sound quality. Moreover, there are fewer automated players that also supplement electronics based music through physical instruments. Hence the robotic pan flute player s absolute objective would be to address these limits. Thus this robotic player will endeavor to relieve from such monotonous and strenuous tasks enabling local musicians to produce wonderful pieces of art. All the more straightforwardly, this paper endeavors to make a robotic musical player that will play the Solomon Island's Pan Flute. Moving on, the revolution of technology in synergy with musical instruments has inspired this engineering problem [4]. Hence the need of an automated Pacific Islands Pan Flute was derived with relation to the Pacific community. The Solomon Island s Pan Flute is chosen for this paper s automation purposes. Even though the Solomon pan flute possesses similar attributes to the conventional pan flutes, it has slight variations from other flutes available worldwide [5]. It constitutes a number of variables, respectively being the pan flute length, pipe diameter, pan pipe arrangement and design. II. LITERATURE REVIEW Music has a distinct meaning to every person and the understanding of the word music differs amongst the ages. According to the WordNet developed by Princeton University, music is an artistic form of auditory communication incorporating instrumental or vocal tones in a structured and continuous manner [6]. An alternate definition is that music is any calming, soothing and pleasant sound derived from an artist or musical instrument. Thus music is universal and subjective. Several examples of music exist. Some of these examples include the basic tweeting of birds, the humming of a tune or a band playing different instruments in cadence. As characterized inside the definition of music, any sound regarded as symphonious to a particular individual may be considered as music [7]. Music identifies with the individual, group and society in different ways. Therefore it is important that such forms of art be recognized. In Wagnerian musical drama, music and words are constant; a mix of the two expresses the inward deeper

2 emotions and considerations which people are capable of. A few musicologists have contended on a comparative point that music does portray a mixture of sounds as well as conveys expressive feelings of significant importance. Richard Wagner, a composer portrayed through a musical dramatization that the social world could be in peace and harmony through music [7]. A. Robotics and music Several types of musical instruments have been automated globally. A History of Robotic Musical Instruments [8], authored by Ajay Kapur, comprises a variety of automated instruments such as percussion instruments like drums, pianos as well as string and wind robotic instruments. While all these instruments are being modernized with reference to automation, a wellspring of electronically created music can be seen consistently developing in the world. Cases of these can be found in music played by our smartphones, laptops and other comparable gadgets. This sort of music is the most common and usually referred to as digital or virtual music. That being said, what is the distinction in quality between the sound delivered by an instrument and the sound created digitally? The quality of sound from the speaker is highly reliant on the capacity of the speaker and the rate at which the signal is sampled. On the contrary, an instrument played by a musical artist transmits all sounds frequencies that a real instrument poses. Today, groups such as TeamDARE [9] and sonic robots [10] are dedicated to continuously automating the different instruments around the world. Currently, TeamDARE also has the only known undocumented automated Romanian Pan Flute in the world. Despite musical instrument automation being around for some time, a verbal survey done amongst undergraduates in The University of the South Pacific demonstrated that there is little information of such automation. This could imply that on a bigger scale people in the Pacific may have not heard or demonstrated a lot of enthusiasm toward this automation area. B. Pan Flute Modelling and Construction The Pan Flute is a representation of an air column with one closed end. Thus the task of modelling the flute simplifies as the physics has already been done. According to [11] the relationship between the frequency and the length of the pipe is given by the equation (1) Where; C f D L = speed of sound, = desired frequency = internal diameter of the pipe = length of the pipe Modifying the length of the pan flute pipe produces a different musical note. In addition, the inner breadth of the flute identifies with the pressure of air needed to produce the corresponding tone. While the length is the characterizing variable in the development of the pan flute, the material that the flute is fabricated of is also of importance. The material identifies the authenticity of the pan flute giving it a cultural value or social significance. Having said that, some basic materials utilized in the development of the flutes are reeds (Solomon Islands), bamboos, oak (Roman) and river cane. Some pan flutes today have also been constructed using polyvinyl chloride (PVC) pipes and even straws adding a modern twist to the concept. [12]. C. The Solomon Island s Pan Flute Fig. 1. Solomon Islands Pan Flute The Pan Flute gets its English name from the Greek God Pan. An old story tells of a lover that had run away after rejection and hid near the river banks by changing into reeds. These reeds were then picked, bundled together and played by the God Pan himself hence originating the name "Pan Flutes" [12]. In contrast, the Solomon Islanders don't get the name from the Greek mythology or some other documented memorable situation. Regardless their adaptation of the Pan Flute is known as 'Au tahana better known to the 'Are'are tribe [13]. The origination of this instrument isn't known precisely. However recorded musical pieces found in 1970s proposes that the presence has been for quite a long time. Varieties of this instrument have additionally been found in different parts of the world hence blurring the origin. Even amongst the Solomon Islands there are varieties of Pan Flute as well. One such variation incorporates 2 rows of pan flute pipes. The size itself of individual pipes can extend from simply a couple of centimeters up to a large portion of a meter or even longer. Moreover, one set of pan flute pipes consists of 8 to 20 pipes. Furthermore, the Pan Flute is seen to fill minimal need other than that what it is fundamentally subjected to entertainment. The flute may be utilized in conjunction with other instruments, singing and dancing to make an exhibit of delightful sounds. Nevertheless, the flute holds the capacity to strive alone. III. SYSTEM OVERVIEW Figure 2 below illustrates the relation between the individual parts. Prior to the system to start, it needs to undergo a calibration process. This is known as click-tocalibrate (CTC) whereby the distance of the pan flute pipes will be given to the calibration module. Utilizing this data, the

3 CTC module will work to distinguish the musical notes from each of the pipes until all the pan pipes have been taken into account. "USB/Serial" is the type of communication channel between LabVIEW and Arduino. For this paper, the team is using the following port pins from the Arduino board: TABLE I. ARDUINO PINS Purpose Pin Number Pin Type Stepper Motor: Stepping pin 2 Digital I/O or PWM Stepper Motor: Direction Pin 8 Digital I/O or PWM Limit Switch NO 33 Digital I/O Fig. 2. Block Diagram of overall System After CTC is finished, the LabVIEW graphical user interface displays all calibrated musical notes which the client can click and play. Each time the user clicks the related pan pipe activation button for a particular note, the pulse width modulation (PWM) value for the stepper motor and PWM value for the RC filter is called. In this manner the stepper motor moves a platform on the linear rail and the transducer changes the speed of air blown into the pipe delivering the related note. A. Mircocontroller The group is utilizing an Arduino Mega 2560 to interface the connection between LabVIEW and the outside world, as LabVIEW can receive and send signals from the Arduino. In order to use Arduino microcontroller with LabVIEW, a library has to be installed before communication can initialize. This is carried out by downloading the VI Package Manager which in turn downloads and installs the Arduino Library. Hence after this operation LabVIEW is prepared to communicate with Arduino taking into account the drivers are preloaded. However, this communication is initialized only in a single direction at the moment - from LabVIEW to Arduino only. For this reason a code known as LabVIEW Interface for Arduino (LIFA) is transferred to the Arduino Mega2560 board by means of the Arduino IDE. The representation contains data on how Arduino will correspond with LabVIEW. At this point LabVIEW and Arduino are fully ready to communicate and the IDE is shut down to avoid port interference. Limit Switch common: +5V +5V +5V pin E/P transducer 3 Digital I/O or PWM Ground: Stepper & E/P transducer ground GND Ground B. Hardware Design The implemented design has two separate modules which are air regulation and positioning. The air regulation circuitry comprises of only one voltage to pressure transducer that will cater for all the pan flute pipes. Fig. 4. System Design Consequently, this implementation is financially savvy as a result of the minimal number of parts utilized. Likewise, this design also produces a robust system which takes into consideration versatility. Moving on, the ability of the rack and the rail to be separated from each other allows for a wider range of pan flutes to be used. Fig. 3. Configuring LabVIEW Figure 3 above is an illustration of the setup in LabVIEW. "COM 5" is the port in which the Arduino is connected which changes for each computer. "9600" is the baud rate. "Mega 2560" characterizes the board that is used. C. The Pipe Rack The pan flute rack is part of the hardware setup which holds the Pan Flute pipes set up. With the end goal of creating an uncomplicated prototype, the pan pipe's inner diameter has been set to 25mm maximum. Hence taking into account the length of the rail and the maximum internal pipe diameter, the most extreme number of pipes that can be accommodated for is 12. This value also takes into account an external diameter of 27mm across each pipe for any miscalculations and offsets. Since the total comes to 324mm, an approximate pipe rack of

4 350mm was set to be constructed. The rack will be made out of a calibration between wood and plastic with rubber cushioning embedded in the inward layer, consequently securing the flute pipes from harm. Fig. 5. Pan Flute Rack D. Click To Calibrate Click-to-calibrate (CTC) process encompasses actions taken by the system to take into account the number of pan flute pipes and their respective musical notes. The user has the option to calibrate or even re-calibrate the same pan flute pipe irrespective of its impact on the other flute pipes. This process starts with the client entering the separation of each flute pipe from a reference point. At that point the system will consequently move the rail platform to the selected pipe. Succeeding this step, the transducer will increase the air pressure from a base quantity. Amid this process the software will listen for a musical note which is predefined in its library. Once a frequency of sound generated is matched with the frequencies specified in the program library, the calibration process stops and the PWM value with the corresponding distance are registered. In a similar way, the rail moves the platform to the next Pan Pipe to be calibrated and process repeats. At the end of the CTC process, the user can see the available notes corresponding to each flute pipe on the LabVIEW GUI. E. The Linear Rail The linear guide being utilized in this project was extracted from an old malfunctioning HP printer. After which, it was checked thoroughly to ensure it was in working condition. This rail came with a DC motor and a platform attached to it. To ease the programming complication, the DC motor has been removed and a stepper motor has been installed in its place as it can be programmed in an open loop control. This stepper motor has a step resolution of 7.5 degrees per step. The purpose of the rail is to aid in aligning the nozzle of a tube which blows air over the pipe. Fig. 6. Linear Rail F. Stepper Motor Driver The motor driver selected for the stepper motor is a A4988 Big Easy Driver Board capable of handling up to 2A [14]. The supply voltage for the driver is between 8V to 35V. The driver can also allow for micro stepping and pass higher voltages to the motor thus achieving higher step rates. G. Air Regulation For a pipe to play a note, the right amount of air must be blown into it at the correct angle. The alignment and angle will be handled by the linear guide. The latter task of regulating the air will be carried out by a voltage to pressure transducer (E/P transducer). The E/P transducer that has been chosen for the project takes in an input for 0 to 5 volts and returns an output proportional from 3 to 27 Psi [15]. To power the E/P transducer a simple 2 nd order filter will be created. The input to the filter will be a PWM voltage which will then be converted to an average output voltage directly proportional to the duty cycle of the pulse. This satisfies the necessary conditions while remaining within the budget constraint. Furthermore the E/P transducer will be connected through reinforced tubing to a compressor. IV. RESULTS A. Frequency Detector Part of the CTC system depends on analysis of the sound frequency. This feedback will be deciphered to point out musical notes that the pan flute pipe corresponds to during calibration. Using the built in microphone in a laptop and its internal sound card, a cheap, minimal and reliable musical note identifier is programmed. The software setup itself is simple. By means of the Acquire Sound express VI in LabVIEW, the computer soundcard takes input either using the onboard microphone or connected microphone and identifies the sound frequency. This frequency is then compared with predefined values of musical notes. To improve accuracy, the Acquire Sound VI is set to 2 channel input, thus specifying stereo quality audio

5 signal. Moreover sampling rate greater than 22.5 khz and 16bit resolution improves precision as well as accuracy. In Fig. 7, a representation of a single frequency detection algorithm is shown. In a similar manner, the program is extended to support a greater range of musical notes with their respective frequencies. Therefore for a rail of length 350mm approximately 594 steps will be required to move from the left most position to the right most position. Since 48steps = 1 Revolution, 594 steps equates to approximately 12 revolutions. C. Click To Play System The click to play module (CTP) is the final product of the Solomon Island s Pan Flute automation system. After the calibration has been done, the user can then click the respective buttons as outlined in the figure below to activate it. As simple as the front panel is, the algorithm behind it can be duplicated to accommodate a larger number of Pan Flute pipes with minor changes in the code. Fig. 7. Sample Frequency Detector Block Diagram from LabVIEW A test run of the simulation shows the frequency detector in operation while audible frequency was being generated using a smartphone via an android app Frequency Generator developed by Denis Joseph Barrow [16]. Fig. 8. Frequency Detector in operation From Fig. 8 it is seen that the frequency detector has been able to pick up the generated frequency verifying that it is Hz with an offset of Hz. B. Stepper Motor Shaft Radius (R) = 9mm Resolution ( ) = 7.5 degrees/step The formula for linear distance (D) covered per step is, (2) Fig. 9. Click-to-Play GUI This system also allows the speed of the stepper motor to be adjusted which can allow variable speeds during the composition and playing of music. In addition, a virtual led is also on the GUI to indicate if the rail platform has aligned itself to the pipe. This is provided due to the fact that the buttons which activate the movement and the air regulator will operate as long as the button is held/clicked. Thus the virtual button simulates a physical push button allowing easier play of the Pan Flute system. Moving on, the data for defining the pipe distance and the PWM is retrieved from the calibration data hence no further input is necessary. The indicators above the pipe number button show the value of the pipe distances once successfully retrieved from the calibration module. D. Click to Calibrate The click to calibrate system starts with the platform first moving to an arbitrary position known as the home position. The limit switch activates once the platform has reached home and then awaits the calibration function. As presented in the figure, the 10 pipe Pan Flute system proposed may be calibrated individually irrespective of each other hence allowing for correction in case of calibration failure. The darker shade of grey block with the print PIPE X (where X is 1 to 10) represents the activation button to begin calibration. Here, the user only inputs the distance to the specific pipes and the rest is handled by LabVIEW. As soon as the activation button is clicked, the platform aligns itself to the respective Pan Flute pipe and the PWM iteration begins from zero. In addition, the front panel GUI shows the iteration values and the musical notes being detected. Once the frequency error goes below 0.01Hz, the calibration exits and the data is captured. This is notified to the user by the change of the virtual led from dark green to bright green color.

6 Upon completion of calibration, the click to play user interface can be interacted with. Hence the system is ready for playback. anticipated that further evaluation of the system will be made for the final version of the paper and presentation at the conference. VI. ACKNOWLEDGMENT The team would like to thank the school for the funding and giving the opportunity to work on this project. We would like to thank the academic staff and technical staff for their support and assistance VII. REFERENCES Fig. 10. Click-to-Calibrate GUI Figure 10 above shows the LabVIEW GUI for the first 5 pipes. It continues in the similar manner for pipes 6 to 10 V. DISCUSSION At the end of the project, a functional automated Solomon Island s Pan Flute is expected to be produced. The device is anticipated to open a gateway for robotic instruments in the Pacific and thus play a variety of music. Moving on, this project does not intend to demean, show favoritism or hurt any society, tradition or culture in particular. It may unintentionally affect a few perspectives as a traditional instrument is being utilized to be played via technological means. To overcome such a hurdle, it could be explained to the people that the attempt to revolutionize the musical area is to keep up with the moving world. This in turn helps preserve their instrument and brings to limelight the hidden possibilities of such an instrument. Moreover upon completion, the automated Pan Flute player intends to fill the role of: - Fast prototyping of music sheets due to the removal of repetitive manual playing - Extension of automation to other wind instruments using similar technology A schedule lies ahead of the team for the completion of the automated player. This involves using a MIDI file to automatically play a song, thus reducing the repetitive effort required to operate the system. To top it off, a simple user manual will be created for easy installation and playing. It is [1] P. Chand and D. A. Carnegie, "Mapping and exploration in a hierarchical heterogeneous multi-robot system using limited capability robots," Robotics and autonomous Systems, vol. 61, no. 6, pp , [2] R. Rahimi and F. Abdollahi, "Time-varying formation control of a collaborative heterogeneous multi agent system," Robotics and Autonomus Systems, p. In Press, [3] T. M. Sobh, B. Wend and K. W. Coble, "Experimental robot musicians," Journal of Intelligent and Robotic Systems, vol. II, no. 38, pp , [4] J. H. McVay, D. A. Carnegie, M. J. W. and A. Kapur, "MechBass: A system overview of a new four-stringed robotic bass guitar," in Proceedings of the 19th Electronics New Zealand Conference (ENZCon), [5] P. H. Buck, "PAN-PIPES IN POLYNESIA," The Journal of the Polynesian Society, vol. 50, no. 200, pp , [6] "Music," [Online]. Available: [Accessed 11 August 2014]. [7] J. Robinson, Music And Meaning, New York: Cornell University Press, [8] A. Kapur, "A history of robotic musical instruments," in MISTIC, [9] "TeamDARE," [Online]. Available: [Accessed 10 August 2014]. [10] "About Sonic Robots," [Online]. Available: [Accessed 10 August 2014]. [11] R. A. Serway and J. W. Jr. Jewett, "Superposition and standing waves," in Physics for scientists and engineers, Cengage Learning, 2011, pp [12] D. Bishop, "A world wide history of the Panflute," [Online]. Available: [13] "The Panflute in the world," [Online]. Available: [Accessed 10 August 2014]. [14] "RV8834 Low-Voltage Stepper Motor Driver Carrier," Polulu robotics and electronics, [Online]. Available: [Accessed 30 August 2014]. [15] "E/P - Series 500X," ValveStoreOnline, [Online]. Available: 77.html?osCsid=19f66c1ccfa70a9fd511506ae38867bf. [Accessed 30 August 2014]. [16] D. J. Barrow, "Frequency generator," 26 November [Online]. Available: [Accessed 30 August 2014].