3.1 - Project Proposal
Introduction:
The booming innovation of technology now allows anyone with a laptop and a musical program to mimic the sounds of any instrument, resulting in the declining trend of “real” music. Playing a musical instrument requires precise motion, muscle coordination, and rhythmic knowledge that not everyone has access to learning or practicing. Not only that, but becoming proficient in an instrument can be long and challenging, sometimes requiring years of practice to master. Considering both of these issues, we propose a way to automate an instrument to reintroduce the original form of music straight from the source and to eliminate the challenges of learning an instrument.
We plan to automate an instrument, specifically a xylophone, by implementing a series of 4-bar mechanisms that mediate the motion of three respective hand-like levers stemming from one base. Each lever will be assigned to a respective key, and for simplicity, we will only be using three keys/notes to play a simple song.
Problem Statement:
The primary challenge for our project is to get the mechanism to play a song on the xylophone equivalent to or exceeding that of a skilled musician. In order to ensure our goal, our mechanism requires precise motion, timed outputs/cycles, and force control.
Goals:
Play/tap a key precisely to mimic a human hand playing a xylophone
Play the keys in the right order to create a melody.. For this reason, our system cannot be solved with simple joints.
Mechanism:
One way to implement our project is with a series of 4-bar mechanisms that will be used to bring a point to each key such that it can be played. We can implement a 4-bar system similar to the one below, where ‘point P’ makes a point of contact with each key. The linkage for our systems will be designed such that the path created by link AP will allow point P to make quick contact and play the key without dragging. Another way to implement our project would be through the usage of a cam-follower mechanism, which is later explained.
Proposed Scope:
We intend to analyze the position of a Point P on our 4-bar mechanism that will be responsible for playing a key, as well as time coordination between the motors that drive the series of 4-bar mechanisms such that the keys are played and create a sort of tune. For our fabrication, we will perform positional analysis to determine what ideal path is necessary to get the point P to just tap the key instead of drag along it. We also need to consider the software aspect of when to play the keys at timed intervals so that we are able to create a tune. We aim to have a complete mechanism that uses three 4-bar mechanisms to play a tune that should somewhat sound like ‘Mary Had a Little Lamb’.
Preliminary Design:
As an alternative route, we could also design a system using a cam follower mechanism. The idea would be to have ridges on the cam that correspond to the notes wanting to be played by the different hammers. We’d be designing our mechanism with motion amplification in mind, taking in smaller inputs on link B to output a larger motion for the mallet to strike the key. This will be a double rocker, with the cam being actuated. This option would make it easier to get the melody to flow smoothly despite the likelihood of the mallets resting on a given key and muting the notes.
For the cam design, we intend to have different cams (max three) to correspond to a key on the instrument. We will divide the surface of the cam to correspond to a distinct note of our song, where a ridge will be placed if it's time for a specific note to play.
Based on our extensive design options, we have yet to decide which route we will take specifically. We plan on building minimized prototypes for proof of concept and determining which design we choose from the results we get. We want to find the design that produces the best sounds while maintaining simplicity. Once we select a design, there are calculations we have to conduct to quantify the logistics and capabilities of our model. Although our approach is slightly backwards, we want to produce a mechanism that will have the best results, and we can only do that through experimentation.
We will quantify our mechanism using Gruebler’s Equation to determine the degrees of freedom of our system, which will confirm our results from prototyping and experimentation. We will also use Grashof’s Law to confirm our prototyping through the verification of a full rotation from the shortest link.