Andrew Cook, Brian Dolat, Adam Fabry, Peter Wagner
ABSTRACT
The focus of this project was to create a guitar fret actuation device, which could be attached to the neck of a wide variety of guitars, and play a significant number of songs, utilizing at most the top four frets of the guitar. The assistive technology device is to be actuated in a manner that eliminated the need for the guitar player to use their hand to fret the guitar. This design was created to help those who have lost the ability to use one of their hands. Several concepts were developed and a final concept was selected using a decision matrix process. A prototype of the selected concept was created. The initial prototype was tested and redesigns were made to fix the problems that were found, resulting in the final prototype.
BACKGROUND
When a person has lost the ability to use their chord playing hand for a guitar, an alternative actuation method is required. The user must still strum the guitar with their functional hand, but the chord actuation will be accomplished using an alternative method. The user interface may consist of a mechanical pedal or an electrical button. After some research of similar products it was discovered that there are very few assistive devices for chord actuation. The Chord Buddy, which is the closest product to the Guitar Fret Actuation System only plays 4 chords and still needs to be pressed with fingers. The next closest device is a fully automated guitar, which is not a product that is currently on the market. Research was conducted on guitar chords and it was determined that it is possible to play over 30 chords on just the top 3 frets. Using a device only on the top 3 frets will minimize the size and the weight of the device, which will make it easier to transport.
PROBLEM STATEMENT
Our goal was to design and build a device that will allow a person to fret a guitar without using a hand. This will allow people who have lost the use of a hand to still play the guitar. We strive to create a device that will enable people to rekindle a lost musical path.
DESIGN AND DEVELOPMENT
Our criteria to meet include the following:
- Solenoids cannot be used to press the strings (based on designs of previous project attempts.
- Chord-to-chord transition speed comparable to competent guitar player
- No more than the top four frets can be used
- Lightweight (able to be attached to guitar neck without hindering the stability of the guitar.)
- Easily attachable/detachable
- Portable
- Chords chosen using an alternative actuation method
- Minimal power dissipation
Many concepts were developed for both the actuation system and the user interface system. The concepts were evaluated using a decision matrix process. As seen in the figures below, the final actuation system design strongly incorporated the initial hook design concept. The device was place around the neck of the guitar by connecting the two female sides using metal dowels. It was secured by tightening the adjustable plate on the bottom of the device until it was pressing tightly on the bottom of the guitar and the top of the guitar was being pressed by the tabs on the top of the device. The adjustable plate and tabs can be seen in Figure 1. Hooks were placed in the slots of the device and attached to cables. Each hook had a spring under it, in which the cable went through. The springs held the hooks off of the guitar strings until the cables were pulled, and then lifted the hooks up again once the cables were released. Figure 2 clearly shows the cable and hook attachment. The cables were attached to the foot pedal system. The protective tubing around the cables was connected to hose attachments on both ends, on the device and on the pedal system. The foot pedal system has rotatable tabs, which can be adjusted to change the chords that are played by the system. Figures 1 and 2 show the initial prototype that was created, for the top fret, as a proof of concept. Figure 3 shows a CAD model of the foot pedal system.
Figure 1: Assembly of Actuation System Prototype (frame, hooks, adjustable plate, tabs, and hose attachments)
Figure 2: Cable and Tube Connection to Actuation System
Figure 3: User Interface System
Figures 4 and 5 show the initial one fret prototype attached to a guitar and the initial foot pedal system.
Figure 4: Initial Actuation System Prototype Connected to a Guitar
Figure 5: Complete Assembly of Initial Prototypes Connected to a Guitar
EVALUATION
In order to ensure quality in the product, a number of tests were performed and analytical data was collected. From the tests, guidelines were determined for performance of the product. The analytical data collected allowed for proper materials and dimensions to be selected for the product. The data gathered from the testing and analysis allows the product to meet the customer’s needs and constraints. Being a fully mechanical design the product does not require electrical power and therefore meets the minimal power dissipation constraint. The actuation system is lightweight and will not hinder the neck of the guitar. The foot pedal system has been fitted with wheels and a handle in order for easy transportation. Using the cable design, the chord to chord transition speed is a good model of a competent guitar player.
CONCLUSION
This project was approached with the realization that two systems needed to be designed. The first was the actuation system that is attached to the guitar and physically presses on the guitar strings. The second is the user interface system that is used to activate the actuation system without using the fretting hand. Many concepts were created and narrowed down to a final design. The actuation system contained a 3-D printed frame that connected to the guitar and supported hooks. The hooks were connected to a foot pedal system by cables. The pedals pulled the cables, which caused the hooks to press the strings. The prototype meets the required criteria. Most importantly it closely simulated the quick transition speed between chords that a competent guitar player has. With this device, the guitar can be played by people who have previously thought it to be impossible. The primary user can be anyone from a wounded soldier who has lost an arm, to an individual who has arthritis or has had a stroke. This device could be used to bring music to the lives of people who never thought they would be able to play again.
ACKNOWLEDGEMENTS
Our group would like to thank our client, Professor Michael Prairie, for assisting in the design process and the research of the guitar chords. We would also like to thank our advisor, Professor Jeffrey Mountain, for his guidance and instruction throughout the entire process. Finally we would like to thank the Norwich University Lab Technician, Timothy Vilbrin, for assisting in the printing of the 3-D printed parts and for guiding us through the manufacturing of the systems.