Product Evolution

When we first developed the idea of an interactive xylophonic keyboard, it took the form to the left. We wanted it to be portable and integrated into one unit. We decided that a folding, briefcase-like design would best allow for both to be fulfilled.

Upon consulting parents, children, and professionals that work with children, we decided to change the original design to resemble more of a piano. The child sits on a bench to play the keyboard. There would be two different modes of play. The first plays the notes that are positioned on the scale automatically. The second mode will light an LED below the first note on the scale and an LED to the corresponding key and wait for the child to hit that key. It will then move to the next note and repeat until all the notes on the scale have been played. The dimensions were based off of similar products.

The mechanical operation of the keys and the xylophone is shown in to the left. A four-bar mechanism would swing up and hit the xylophone when the key is pressed. When playing automatically, it fires a push solenoid into the four-bar to hit the xylophone. This creates a player piano type of keyboard.

The first CAD model of the prototype is shown to the left. We decided that a three-key keyboard, three notes, and three sliders would demonstrate that our concept for a final product would be feasible. The black box is a protoboard that holds the majority of the electronics. The housing for the keyboard and xylophone is open to easily allow one to see how the prototype works and to allow for easy accessibility to the majority of the parts in the case of malfunction. There is a bus cable connecting the main housing and the slider housing to the protoboard.

The separate housing for the sliders and the keyboard and xylophone are combined into one unit, more closely resembling the proposed final product. The keys, xylophone, and four-bar linkages are shown with more detail and dimensional accuracy. The protoboard is not shown in this CAD model.

This CAD model is even more detailed, showing the key sensors (green) and the solenoids (orange). The solenoids are not placed beneath the four-bar linkage so that they would hit the four-bar which would in turn hit the xylophone plate and create a player piano type of keyboard. This idea was found to be unneeded and not essential to the final product.

The protoboard was replaced with circuit board and integrated into the slider housing to conserve space and make the prototype more presentable.

After the four-bar mechanism was produced, we discovered that the striking-hammer caused a damping effect on the xylophone plate, producing a poor-quality sound. An attachment was added to the four-bar support and the final link of the four-bar mechanism was modified so that a pin would be lifted to strike the xylophone plate. This produced a much better quality sound without changing the basis of the four-bar mechanism.

Looking more closely at the striking link of the four-bar mechanisms, shown in the images below, it is easy to see the changes made. The striking hammer was originally designed to look like the model to the left. After that was manufactured, it was discovered that it did not produce good sound quality, and it was redesigned to look like the model to the right.