Overview

This installation consists of a laser harp that plays sound when a laser is broken by physical intervention. There may be an option to make the lasers hidden so that the actual mechanism is hidden from visitors. A system of mechanical fingers that can “play” the laser harp will accompany it and can be programmed to play songs. Sounds played from the laser harp will be amplified through a speaker/amp that will additionally have a visualizer in the form of LEDs to display the frequencies of the sounds being played.

For the Children’s Museum of Pittsburgh, this installation would do well in a dimly-lit room with enough space to fit the installation. Examples of such spaces would be the room across from the Attic or the various dark hallways, which all house similar installations that include light.

A typical visitor experience would start initially with curiosity and a cursory evaluation of the installation, including specifically looking for instructions for how to use the installation, which may or may not be included. A visitor may explore the frame of the harp, which initially will not have the lasers visible, and may stick their hand, or other limbs, through the space, which will trigger sounds to be played on the amp/speaker. Visitors may then realize they have some aspect of control over the sounds and may create their own sort of song. After, visitors may notice the mechanical fingers and attempt to control it. The fingers may be accompanied with simple instructions on how to get it to play a pre-programmed song. Some visitors may be interested in creating their own songs from directly using the mechanized system.

A hallmark of success would be any interaction with the installation that may spark curiosity on how the laser harp works. Another hallmark would be the individual creation of music by visitors, which should be prompted by the awareness of their control of the installation. We expect to observe a lot of physical interaction with the installation, including stepping around the laser harp and manipulating the mechanical fingers.

Technical Outline

This project will consist of three main parts: the mechanical fingers, the speaker/amp, and the harp itself.

The harp will be relatively simple and robust since it is the part that is meant to be roughhoused the most. It will consist of a simple wooden frame with inlaid laser diodes and photo sensors. There could also be an onboard Arduino for processing the signals, but it is unclear at this point if that is necessary. An Arduino would increase the complexity of the harp, but also reduce the number of wires in the harness that goes to the speaker. Wood, laser diodes, and photo resistors are already at our disposal, making this part simple from a materials perspective. Calibrating this part should also be relatively easy, since the difference between a laser directly on a sensor and background light should be significant.

The mechanical fingers are not meant to be touched, but will have to be robust for the inevitable touching they will receive. We have not yet decided upon the exact mechanism that we will use for this task. That being said, the simple micro hobby servos we have will probably work best for driving whatever mechanism we use. Plywood will work well for this part of the project due to its relative strength and ease of working. They will probably play a randomized tune when the harp is in place. When to play will be determined by a micro switch in the base of the harp stand.

The speaker / amp is going to be the most technically challenging due to the musical aspect of this project. It is easy to play pure tones from an Arduino, but not higher fidelity sounds. Thus the amp will have to contain a more advanced controller, such as a Raspberry Pi. A portable speaker can be combined with the audio output of the raspberry pi to create the necessary sounds. The box may also contain LEDs to display the different frequency content of the sounds being played on the top of the box. All of the aforementioned components will be tied down inside a robust plywood box, making it difficult to break this part of the project.

Timeline

The timeline can be found here: Project Proposal: Timeline & BOM.

Project Management

We will divide the responsibilities equally across design, fabrication, and documentation. Nick will be mostly responsible for the electrical portion of the installation while Sora will be mostly responsible for the mechanical portion. However, integrating the two aspects for each part of the installation will be done together to ensure a smooth working demo. Documentation will be done for parts by their respective designers and any artistic additions will be made together.

For this installation, we will need proof-of-concept demonstrations for the laser harp, programming the mechanical fingers to play the harp, and the amp/speaker in addition to the visualizer. These proof-of-concept demos should simply ensure that the specified portion of the installation is feasible and should be done quickly. If they succeed, they can be later scaled to the appropriate size so as to accommodate the envisioned scope of the installation.

For the first on-site test, making sure the laser harp works and responds to physical interaction should be the priority, in addition to its robustness in the hands of children. Next, we should make sure the amp/speakers work so that sounds coming from the laser harp can actually be heard. If those succeed, then we should then prioritize the mechanical fingers and their ability to successfully “play” the harp and follow their programming to play a specific song. Robustness for the mechanical fingers at the mercy of children should also be noted and carefully observed during the on-site test. The visualizer is last in priority as it is not essential to the installation. However, if the previous demos succeed at the first on-site test, then testing the visualizer should be next in priority. Otherwise, it can be tested later at the Children’s School and hopefully be integrated for the final test at the Children’s Museum.

Budget Outline

The Budget Outline can be found in the “BOM” tab here: Project Proposal: Timeline & BOM

Currently, the budget for the project is $100 for the portable speaker, raspberry pi, and LEDs. This could come down with alternative part selection and savvier shopping. Most materials should be able to be sourced from the lab. If there is something we cannot find in the lab, the additional cost should be minimal compared to the cost of those two items.

 

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