ElectroMagnetic Guitar: Chord Playing Support System on Guitar by Electromagnets
1. ElectroMagnetic Guitar:
Chord Playing Support System on Guitar by Electromagnets
IWAIT2020
Nozomu Yoshida, Katsutsugu Matsuyama
Faculty of Science and Engineering, Iwate University,
4-3-5, Ueda, Morioka-shi 020-8551, Japan
4. Difficulty in chord form Magnetic force support
Normal Guitar EMG
For beginner
5. RELATED WORKS
(AUGMENTED GUITAR)
Biostomp [1]
Biosignal interface that controls
effector knob by muscle movements.
MagPick [2]
Used electromagnetic interference for
extending guitar playing expression.
[1] Ç.Erdem et al., "Biostomp: A Biocontrol
System for Embodied Performance Using
Mechanomyography," NIME 2017.
[2] F.Morreale et al., "Magpick: an Augmented
Guitar Pick for Nuanced Control," NIME 2019.
6. RELATED WORKS
(SUPPORT & SIMPLICATION)
Haptic marionette [3]
Controlling human hand posture by
EMS and hanger reflex.
Mountain Guitar [4]
Compact guitar that realizes easy
control of sound pitch by gesture.
[4] J.Kanebako et al., "Mountain guitar: a musical
instrument for everyone," NIME 2007.
[3] M.Sakashita et al., "Haptic Marionette: Wrist
Control Technology Combined with Electrical
Muscle Stimulation and Hanger Reflex,"
SIGGRAPH Asia 2017 Posters.
12. USER STUDY
Question
(Q1) How was the power to draw your fingers?
(Q2) How was the power to keep your chord form on the guitar?
(Q3) How about the comfortableness of EMG?
(Q4) How was the heat generation of the guitar?
Condition
• 24 participants
7 experienced persons
17 Inexperienced persons
• 10 minutes on average
5 min for preparation
5 min for playing
13. USER STUDY
Condition
• 24 participants
7 experienced persons
17 Inexperienced persons
• 10 minutes on average
5 min for preparation
5 min for playing
0
2
4
6
8
10
12
14
16
18
20
(Q1) Force to DRAW fingers (Q2) Force to KEEP chord form
Result of magnetic force
Adequate Weak Absent Others
1
16
3
4
19
2
3
0
14. USER STUDY
Condition
• 24 participants
7 experienced persons
17 Inexperienced persons
• 10 minutes on average
5 min for preparation
5 min for playing
Question
(Q3) How about the comfortableness of EMG?
-> 4 people reported discomfort because of its thickness.
-> No one pointed out the prototype’s heaviness.
(Q4) How was the heat generation of the guitar?
-> No one pointed out the prototype’s heat generation.
15. (1) Magnetic force
-> A big gap in magnetic force between DRAW and KEEP
-> Exponential decay of magnetic force according to distance
c.f. Exponential decay
Force
Distance
Result of magnetic force
DISCUSSION
0
5
10
15
20
(Q1) Force to DRAW fingers (Q2) Force to KEEP chord form
Adequate Weak Absent Others
1
16
3 4
19
2 3
0
17. (3) Experienced people tend to feel less magnetic force
-> Experienced person physically remembers how to use the
muscles to press the chord (the muscles are working properly)
Experienced Inexperienced
Influence of magnetic force
DISCUSSION
18. (4) 4 people who answered ‘Others’ (couldn’t use EMG properly)
-> Undetermined pulling force / unique chord form / small fingers
Why ’Others’?
Gradual fall power
Small finger
DISCUSSION
4
19. DISCUSSION
(5) Limitation as the performance supporting tool
-> Discomfort of bending finger joint and fingering / Incorrect sound
Limitation
No guitar techniques
Incorrect chord sound
Discomfort to bend
20. • Introduced ElectroMagnetic Guitar (EMG) that realizes easy
chord playing on guitar by using electromagnets.
• Designed the guitar interface concept and made a simple
prototype as the first step.
• Potential of chord supporting especially in chord form
keeping, though not having enough power to draw fingering.
CONCLUSION
21. ElectroMagnetic Guitar:
Chord Playing Support System on Guitar by Electromagnets
Nozomu Yoshida, Katsutsugu Matsuyama
Faculty of Science and Engineering, Iwate University,
4-3-5, Ueda, Morioka-shi 020-8551, Japan
IWAIT2020
Editor's Notes
Hello everyone, I’m Nozomu Yoshida from Iwate University in Japan.
Now I have a presentation about ElectroMagnetic Guitar: Chord Playing Support System on Guitar by Electromagnets.
You may think it’s not the topic of IWAIT, but hope you to think it as one of the multimedia applications in the board sense.
In this research, we introduce ElectroMagnetic Guitar, a new guitar interface that supports chord playing mainly for beginner guitar players.
In the case of right handed players, they play the guitar with their left hand’s fingers on a fretboard and pick the strings with their right hand’s fingers, and our EMG guides the player’s left handed fingering by magnetic force.
To realize such a concept, we made an original fretboard with controllable electromagnets mounted and attached it to a normal classic guitar.
EMG ‘draws’ player’s left hand fingers with iron plates attached toward proper chord positions on the fretboard.
Generally, a guitar beginner cannot press a string correctly when playing a guitar chord.
We propose EMG for the purpose of supporting beginners' fingering of a guitar from a body control approach.
There are many devices and systems previously proposed that enable performers to augment their guitar playing.
For instance, Biostomp uses biosignals to increase input channel for controlling effector knob while playing the guitar.
And MagPick uses electromagnetic interference between magnetic pick and guitar pick-up to extend guitar playing expression.
On the other hand, many devices and systems that directly control user’s hands have been proposed in previous studies.
Haptic marionette proposed a method for controlling human hand posture by combining electrical muscle stimulation and hanger reflex.
Additionally, Mountain Guitar is a compact guitar that can be played by everyone, such as beginners and children.
With reference to these related studies, we propose EMG for the purpose of supporting beginners' fingering of a guitar that requires delicateness from a body control approach.
This figure shows the structure of EMG prototype.
This prototype was created to test how effectively fingers could be pulled toward a specific limited low chord.
We made an original fretboard for embedding electromagnets.
Our fretboard consists of a medium density fiberboard.
18 holes (6 strings * 3 frets) are drilled into the MDF board by laser cutter for embedding electromagnets.
Our electromagnets are composed of enamel wire and assembly screw as the iron core.
Electromagnets were embedded into the three positions pressed by the chord C, and dummies were inserted in other positions.
The position of each electromagnet can be changed manually.
The figure of circuit shows how the electromagnets are controlled.
Each electromagnet can be switched on and off by the Arduino.
3V dry cells power each electromagnet.
Solid State Relay is used to prevent Arduino from excess current.
In order to use the magnetic force of EMG for string pressing, we fixed a thin iron plate on each fingertip and wrapped them with a rubber finger sack.
This slide is the overview of our proposed method.
Thus, we made EMG prototype by designing;
Electromagnets
Original Fretboard
Fingerstall
Circuit
This is a prototype demo movie.
The three electromagnets embedded in the position of code C are turned on and off every 2 seconds.
As you can see, the fingers are slightly pulled toward the chord position by the magnetic force.
4. USER STUDY
With 24 participants including 7 experienced and 17 inexperienced persons, we conducted an informal study to test how effectively fingers could be pulled toward ‘C’ chord position.
After a brief verbal description of the system, the users were given about 5 minutes to play.
Then the participants were asked to answer four subjective questions, which consisted of:
(Q1) How was the power to draw your fingers?
(Q2) How was the power to keep your chord form on the guitar?
(Q3) How about the comfortableness of EMG?, like heaviness of the body, and thickness of the fretboard
(Q4) How was the heat generation of the guitar?
Lastly, the experiment ended with free feedback from participants.
This graph shows the result of (Q1) and (Q2), which are about magnetic force of EMG.
As for magnetic force to DRAW; 1, 16, and 3 participants reported it to be adequate, weak, and absent respectively.
As for magnetic force to KEEP chord form; 19 people reported adequate magnetic force to keep their chord form.
Regarding (Q3) and (Q4), 4 people reported a feeling of discomfort when holding the fretboard because of its thickness and no one pointed out the prototype’s heaviness or heat generation.
5. DISCUSSION
As a result of magnetic force, it seems there is a big gap in magnetic force between DRAW and KEEP their finger.
Specifically, Our EMG prototype offered sufficient magnetic force to KEEP chord form despite the weak power to DRAW fingering.
The weakness seems to be caused by the exponential decay of magnetic force according to a distance between the electromagnet and the fingerstall.
As for the thickness of the fretboard, 4 people reported a feeling of discomfort when holding the fretboard.
One of the solutions is to make it thinner by embedding electromagnets into a normal guitar fret.
From the experimental results, it was found that experienced people tend to feel less magnetic force than inexperienced people.
We assume this is because the experienced person physically remembers how to use the muscles of the fingers, wrists, and arms to press the chord, and the muscles are working properly when the chord is pressed.
On the contrary, it seems that inexperienced persons do not know how to apply the force necessary for string chording, so they are naturally in a relaxed state and are relatively susceptible to magnetic support.
There were 4 people who couldn't answer the question about EMG's ability to pull fingers.
The reason was that the pulling force changed and could not be determined uniquely.
We assume this is because the magnetic force decreased with the gradual fall in power.
Also there were subjects who held the guitar with a unique chord form, and who had small fingers and did not reach the strings.
The existing EMG system has limitations as a performance support tool.
For example, a finger sack attached to the fingertip makes it difficult for the finger joint to bend and uncomfortable to play.
In addition, flexible fingering becomes difficult, so you can't use performance techniques such as slide and pulling-off.
Also, in the informal user study, the nut and bridge for raising the string height often came off by the tension of the strings for standard tuning, so the correct chord sound could not be output. This was due to the weak fixing of the nut and bridge.
Therefore, it is appropriate to use it as a performance support interface for a beginner to learn how to press a chord.
6. CONCLUSION
We introduced a new augmented instrument named ElectroMagnetic Guitar that realizes easy chord playing on the guitar by using electromagnets.
Specifically, we designed the guitar interface concept and made a simple prototype as the first step to realize the concept.
As a result of our user study, participants reported EMG potential of chord supporting especially in chord form keeping, though not having enough power to properly draw fingering.
We plan to improve upon issues such as weak magnetic force and comfortability in the future.
