Abstract

The interactive xylophonic keyboard is an instrument designed to motivate four to six year old children to develop an interest in music, by fusing recreation with education into a single product. More specifically, this product was designed to teach the early fundamentals of music reading while helping children develop the coordination necessary for playing the piano. The key technical challenges encountered were the development of an effective mechanism for striking a xylophone plate when a key is hit by a user, development of a system to recognize the note the user selects on the interactive musical staff, and integration of all the electronics. After 13 weeks of development of the concept, the Mini-Mozarts have developed a working prototype proving the feasibility of the product.

The interactive xylophonic keyboard is an instrument designed to instill a musical interest in three to six year old children and help them to learn to read music and begin to develop the coordination necessary to play the piano. The basic idea of this product is a small keyboard that interacts with a musical staff with sliding notes. The keyboard consists of keys that engage a mechanism that strike their corresponding xylophone plates. The sliding notes are used to teach the child that positions on a musical staff correspond to certain musical notes. This product will have three modes of operation: manual, automatic, and interactive.

Figure 1: CAD Drawing of Prototype

In the manual mode, the child will be able to play the instrument without interacting with the electronics. This will allow for children to use the instrument in an exploratory fashion so they can simply strike different keys and hear what different combinations of notes sound like.

The product will also have a demonstration feature. There will be a pre-programmed song which the instrument will automatically play when the user presses the demonstration button. After playing the song the instrument will then teach the user how to play the song. The manner in which this is done is identical to the process delineated above in the interactive mode explanation.

It was found that some parents and educators prefer to teach their children using more organic and less electronic instruments. This product entails electronics, however, in order to appeal to these parents and educators, the method in which the xylophone plates are struck is purely mechanical. For this reason, a four-bar mechanism was designed to strike the plates when the keys are pushed. Even though the product requires electronics when used in the demonstration or interactive modes, a child can hit a key and can sense his or her force actuating the mechanism, thereby causing the plate to be struck.

Figure 2: Notes to be represented by slider board

From the very beginning of the design process, the focus was always on education. The Mini-Mozarts wanted to develop an instrument that fused music with education. The design team researched what types of products were on the market that fit this purpose and found that there was nothing that attempted to give young children a basic understanding of reading music. Most products were simply scaled down versions of existing instruments, or merely toys with buttons to play purely electronically generated noises. The Mini-Mozarts found a void, and deemed it appropriate to pursue the development of an interactive instrument of educational value.

Interviews with Sandra Isaacs, a piano teacher in Great Falls, VA, and Terri Kosik from the Early Childhood Development Center (ECDC) at the University of Notre Dame provided useful information about children’s interest in music. Mrs. Isaacs said some of her students begin at about the age of five or six, and often it is a child’s ability to read and their finger strength that allows them to learn the first fundamentals of the piano quickly. She also stated that if somebody is going to learn to play the piano, it is best for them to start as early as possible, because as a child gets older it becomes more and more difficult to develop the coordination. Furthermore, children who start at a later age can become discouraged when they see that their peers who started when they were younger are more advanced.

Mrs. Kosik, with the ECDC, stated that her organization does not purchase any toys or instruments that use electronics. The philosophy is to let the children make the music, instead of having them press a button and have noise come out of a speaker. This line of thought is popular among many parents and educators. To allow for the unique interactive component of the Mini-Mozarts’ product, electronics are necessary when utilizing the Xylophonic Keyboard in the interactive or demographic mode; however, to satiate the more traditional inclinations of some parents and educators, it was ensured in the design process that the action causing the xylophone plate to vibrate upon a key press be purely mechanical. For this reason, the four-bar mechanism in Figure 3 was designed.

Figure 3: CAD drawing of four-bar mechanism

It was also found in the interview with Mrs. Kosik that four to five year old children learn by imitation. More specifically, they learn by watching, noticing, and then acting. This product would be effective in helping teach the fundamentals of reading music. With the interactive mode, the child would learn that certain keys correspond to specifically located notes on a staff. Furthermore, with regards to helping them learn to play simple songs, the automatic mode would allow them to “watch” and “notice,” and then the interactive mode would guide them in “acting”. Furthermore, children will be able to develop their musical creativity by learning how different notes sound in relation to each other, and how those notes are represented symbolically.

Through the interviews it became evident that children under the age of four are not capable of reading music yet but can still use the instrument in an exploratory fashion by striking the keys and hearing the notes played. Even at a young age, the act of hitting keys to play notes can help develop a child’s auditory awareness through creativity and self-expression. Even though most children under the age of four won’t benefit from the interactive component, they can still use the instrument manually to engage their creativity.

The Design Process was guided by the Gantt chart shown in Figure 4, which was provided by the Senior Design management team. The major deadline that drove the project was the Prototype Demonstration date, by which the team had to present a working prototype of the concept. Given that the Mini-Mozart team had to develop a non-existent concept into a working prototype in such a short amount of time, the team also developed its own more detailed schedule to break down tasks necessary to accomplish in order to meet the deadlines. The team specific schedule included items such as when to order parts, when to have certain sub-assemblies completed, and when to have the circuitry finished. These deadlines were met with varying regularity, but the design team was never faced with a scenario where it had to make an imprudent decision because of project delays. The project was limited by a $400 budget, and in order to ensure that the budget was not exceeded, a detailed bill of materials was kept to keep track of all expenditures.

Figure 4: Gantt chart of design schedule

The first part of the process was to choose a concept to develop. From the onset the group decided to focus on an instrument for children. The rationale was that in order to produce a potentially marketable product in a three and a half month period, the product would have to be simple. Furthermore, for a child to take an interest in a product, it needs to be simple. After conducting research of products on the market and interviewing Mrs. Isaacs and Mrs. Kosik, it was decided that the product would have to possess educational value to be of interest to parents and educators as well. After several brain-storming sessions, the interactive xylophonic keyboard concept was chosen.

With the market and concept chosen, the team set certain design requirements that the product would have to satisfy. The product would have to be capable of being played automatically to allow children to learn by watching. It would have to be capable of being played manually for exploratory use. For an effective interactive mode, it was decided that the product would need negative feedback for when the wrong key is struck and at least eleven keys to cover all the notes from “middle C” up to the “F” at the top of the treble clef staff. After the design requirements were established the important components of the concepts were identified, and each member conducted a trade study on one of the selected components. The trade studies were conducted on the following: xylophone plate material and dimensions, four-bar mechanism to strike the xylophone plate, potentiometer selection for the sliding notes on the slider board, the pinned key – spring system, and the control logic. Upon completion of the trade studies, each team member ordered the parts corresponding to their trade study.

Each team member was then given responsibility over a certain portion of the project. One person was responsible for the CAD model, one for the CAM, one for the circuitry and logic, one for the website, and one for the documentation. The team cooperated in each of these functions, but every member was responsible for their specific task. Upon delivery of the outsourced parts and completion of CAM produced parts, the entire team collaborated in the assembly of the prototype.

Four-Bar Mechanism

Key Features: configuration shown in Figure 5

Key Challenge: hundreds of possible configurations present hundreds of options to produce sound from the xylophone bar

Figure 5: Schematic of four-bar mechanism

Xylophone Plate Material

Key Features: material properties shown in Table 1

Key Challenge: each material requires different plate dimensions in order to produce the desired note when struck

Table 1: Properties of materials for xylophone plate

	Aluminum	Stainless Steel	Copper
Density (lbs/ft3)	10,400	29,000	17,000
Modulus of Elasticity (ksi)	168.5	490	559

Table 2: Optimal four-bar mechanism dimensions

One of the other concerns was the selection of material for the xylophone plates. The key engineering challenge was that each different material requires different plate dimensions in order to produce the desired note when struck. Table 1 lists the relevant properties of the materials chosen for analysis. These materials were chosen by benchmarking existing products on the market.

Table 3: Optimal four-bar mechanism dimensions

The prototype developed by the Mini-Mozarts demonstrates the feasibility of the concept. In order to prove the concept, three keys and three sliding notes are incorporated into the prototype. The Automatic and Interactive modes are fully functional, and the four-bar mechanism provides for an effective manual mode of operation while the Demo mode automatically played the entirety of “Mary Had a Little Lamb.” The key to this concept is not the keys, xylophone plates, or sliding notes individually, but rather the integration of all the components into a single product.

Figure 6: CAD Drawing of Revised Four-Bar Mechanism

The prototype also proves the versatility of the concept. Multiple other functions can be built into the final design from the software platform created in the prototype. It successfully demonstrates the Interactive, Automatic, and Demo modes of play, but in the final design, the product could incorporate new functions such as a metronome or additional recorded demo songs. Furthermore, a function could be implemented in which the product would record what the user plays and play it back automatically. The greatest asset of the prototype is this versatility, which allows the Interactive Xylophonic Keyboard to be equipped with new functions and facets.

The Mini-Mozarts find that the Interactive Xylophonic Keyboard is a feasible concept and strongly encourage development to a full prototype. The proof of concept that has been developed fully meets the design grading rubric established to quantitatively evaluate the prototype and also satisfies the qualitative guidelines constructed from market research. The proof of concept shows a high entertainment value; not only do adults and college-age individuals enjoy the concept, but similar products devoid of the education component are a popular children's toy, clearly showing the entertainment value offered by the Xylophonic Keyboard. Additionally, the concept demonstrates the necessitated educational aspect. The methods by which the child receives feedback from the device, constructs and listens to a song, and hones finger-strength in preparation for actual pianos have been lauded by college professors and child education specialists. Lastly, the product concept is clearly new and unique. While there are products on the market that are entertaining or educational, very few are both. There are absolutely no products, furthermore, that teach children the essentials of reading music. Due to the product's satisfaction of the grading rubric and completion of the qualitative demands, the Mini-Mozarts fully support the further development of the Xylophonic Keyboard and believe it would be a success on the market.