People with multiple severe disabilities often encounter the difficulties of playing a music instrument due to their mental and physical deficits.
Health care institutions which facilitate housing, learning opportunities and day care for these people often encounter the difficulties of communicating with their clients. These institutions experienced that making music together is a great way of communicating and therefore many institutions offer music therapy. According to music therapists, the main goal is having fun. It is proven that people learn more when having fun. When playing an instrument, clients can share emotions and practice their motor skills.
We have designed a musical instrument which is easy and fun to play, not just for people with severe disabilities, but for everyone: the Airdrum. The Airdrum is a small device containing panels with motion sensors and colored lights. When somebody moves their hand or head above the panels, they light up and they play sound.
All of the individual parts will be thoroughly explained in coming logs.
Goals and plans for further improvement
We have three goals concerning the further improvement:
We want everybody to play and interact with the Airdrum. Varying from people who are to experience their first musical device to the professionals, who can use the Airdrum as input to their compositions.
While exploring the various specializedinstruments for the above mentioned audience, we found out that these are very expensive. Often even more expensive than professional electronic or acoustic instruments. We want the Airdrum to be played by a broad audience so a reasonable price must be a concern.
We want the Airdrum to be as versatile as can be. It must be possible to choose (custom) sounds and lights.
With accessibility, affordability and adjustability in mind, we want to implement the following ideas for the next build logs:
Creating an improved functioning prototype
Connecting the prototype with a smartphone or tablet to configure the Airdrum
First impression of the well-known song: Frère Jacques played on the first prototype of the Airdrum.
The speakers are located on the left and right sides of the case. The cones of the speaker are somewhat resistant to splash water as long as they are wiped off again.
The PCBs are placed in a pit. This means that a glass plate can be mounted on top of it. Through this pit, there is room to diffuse the light from the LEDs.
A diffuse plexiglass plate is attached on the top for two reasons. Firstly, it can protect the PCBs. Secondly, it is desirable that it looks like the surface is lighting up rather than separate LEDs. This can be done by placing this diffuse plexiglass plate.
The shape of the device.
We first considered a round shape during the initial design. When the user is reaching for the back panel, his/her arm comes above the front LEDs and this triggers the front sensor. As a result of this, two sounds will be played instead of one, which is not the intention of the user. This is why we used a half-moon shape at the current design. We have chosen for six PCBs because of several similarities with other instruments. A guitar has six strings. Chord basically consist of three notes so the notes of two chords can be played. Furthermore, is it possible to set up and play a pentatonic scale plus an extra root note.
We’ve created a morphological chart/overview to compare and determine the needed components, which is a tool used in design processes. In the left column are the functions the Airdrum has to realize (see our previous log). In the rows are all the solutions we came up with. We’ve considered the pros and cons of each solution. Our choices and descriptions can be found below this chart. The orange line in this chart shows the chosen solutions. These are combined to realize our design.
There are several ways to detect the distance between two objects with hardware. The goal here is to detect and measure anything that comes above a particular sensor. Because the Aidrum can be played in various ways, the sensor has to be chosen wisely. The Airdrum has to be durable, cleanable and be sensitive enough to be played by all limbs or objects the user is able to use.
An ultrasonic sensor is a widely used piece of hardware with quite a range and precision. The drawback of this sensor in this particular case is that it can’t be cleaned from incoming dust nor can it withstand water.
There is a wide variety of the SHARP IR-sensors. All of them with different specs and sizes. The sensor isn’t chosen for several reasons:
They are too expensive (+- 10$)
The sensor has a case with build-in lenses. With this case it will be hard to mount them in the Airdrum.
This casing can’t be cleaned easily.
The self-built IR-distance sensor works almost the same as the Sharp. An infrared light pulse is used for measurement. The sensor receives IR-light photons through reflection of an object or limb. Since the sensor is self-built it will not be affected by dust or water and it can be mounted in any particular way.
The 6 panels have to be measured simultaneously. We have chosen an Arduino for this processing for a couple of reasons:
It can process all of the needed IO.
The Airdrum has 48 WS2812 LEDs in the current design. All of these LEDs can be driven with the same processor.
It can be used for further MIDI upgrades.
It is not desirable to play the instrument with any cables attached. This is why a built-in battery will be used. Before choosing a suitable battery, the to be consumed power has to be considered and calculated. The instrument has to be played for a reasonable period of time before it needs to be recharged.
One of the main requirements for the Airdrum is the minimal need for additional devices. To enable configuration of sounds, sensitivity and colors, some kind of interface has to be realized.
One solution is performing certain gestures (e.g. hitting the outer left and right panels at the same time). We have tried this in an early stage of prototyping, but it turned out to be quite inconvenient. Therefore, we decided that an additional device is needed for configuration. We’ve came up with three ideas: laptop, smartphone/tablet or a (LCD) screen.
If we want to use a laptop, a custom application has to be developed. The Airdrum can then communicate by USB or Bluetooth. USB has the disadvantage that the user needs to connect the Airdrum with a laptop with cable when he/she wants to configure. Also, creating a USB-port will make the Airdrum less water resistant. For these two reasons, using a PC or laptop is not the best solution.
If we want to use a smartphone or tablet, an application has to be developed as well. The Airdrum can connect with smartphone and tablet by Bluetooth. Furthermore, everybody owns a smartphone these days. In addition, all extra hardware required for this solution is already implemented in the Rpi3. The Rpi3 will be placed inside of the case of the Airdrum, so, compared to a USB-port, water resistance won’t be a problem.
A third solution is creating an interface on the Airdrum itself, for example a LCD-screen with rotary controls. This has the advantage that the Airdrum can perform as a...
We have created a function tree, which is a designing tool. Each block represents a function that the Airdrum has to realize. These functions will help determining the components in a following log. The higher the function, the more important the function is.