Our musical machine is a percussive instrument that uses servos to hit a cut-open metal soda can. Each servo strikes the can at a different point; one strikes at the bottom, while the other strikes the surface inside the can. In terms of a percussion instrument, the servos are the actuators of the system, and the can is the resonator. Because the actuators are each placed on different points of the can, they both produce different tones. We imagine you could vary the resonator to whatever you want; Some of the things we considered were cardboard boxes, pieces of plastic, and large screws (these make really cool sounds). As long as you can arrange the servos and mount them on the resonator, you can add it to the system. One of the servos is randomly triggered by a seed, generated randomly based on the amount of time it has been since the Arduino has been powered on. The other servo is sequenced, and it can be programmed with any rhythm that you’d like it to play.
Team Members: Nathan, Harry, Christopher
MU 2801-A01 : A Term : 2023
We wanted to create a machine that would be able to play multiple different sounds through the use of servo motors. It was an interesting concept to us, and we worked on and changed the idea around until we were satisfied with it. We also wanted to use randomness and machine/actuator sounds as features of our design. Amplification is not very important to us; ideally, you would mic the machine or use an amplifier so you could hear it better. Alternatively, you could use contact mics to get sounds out of it. We also like the idea of a moving, kinetic sculpture. An easy way to do this would be to use gravity as part of our design. While the machine works, it should move in a randomized way, making the performance more engaging.
There is a lot of media that showcased the automation of percussion instruments. For example, drums are most likely one of the most automated percussion instruments today. These types of percussion machines inspired us to try and use percussion on other objects, which led us to build this machine. Projects amplified quieter things influenced us as well. We particularly liked how Marble Machine takes quieter tones from contact mics and a bass guitar and turns them into something a lot fuller sounding. Our machine is made to benefit from that sort of environment, where it will have multiple microphones connected to it.
We want our machine to have at least two points where it contacts the can, making a moderately audible sound wherever it contacts. The servos can contact the can at any points that we want; we will search for the best-sounding positions. The design should be somewhat modular. We want to be able to program any rhythm into the machine (within reason for the servo to perform; there are limitations to how fast it can go). We want it to be reasonably loud, but it doesn’t need to be as loud as a traditional instrument. By design, it will be made to be amplified.
Our first design used two servos, but in a different manner than our final product. Each one had nails on either end of its rotating part. The two nails would hit different actuators. We initially wanted to have the nails contact 4 different objects: a cut-open soda can, a large metal screw, a piece of cardboard, and part of a chip clip. When we built our first mockup, we quickly realized that having two nails on each servo was inessential, as one nail on each servo could rotate to hit two objects, if we handled the angle it had to travel in the code. It also fixed a potential problem: with two nails on each servo, it was possible for the nails on opposite servos to collide with each other, making some rhythms hard to play.
However, we decided to change our design to the one seen in Figure 1, as we felt this simplified our core idea by only using one resonator. We went forward using only the can, because it made the most interesting sounds. This project could definitely have been done with another resonator, though. We cut open the can to produce a tone that we liked more, and decided on where the servos should sit. Through coding, we figured out how to make the correct angles with the servo, so we could hit the can to produce the sound we wanted.
During our brainstorming sessions, we considered putting something inside the can, so it would act like like a maraca or a shaker. However, we found that our servos didn’t generate enough force for this sound to be heard, so we ended up not going forward with the idea.
To create a stochastic element, we developed an algorithm to produce random movements with the servo that touches the inside of the can. Once this was finished, and we figured out how to perform processes in parallel, we were done with the machine.
BOM:
| Part Name | Price | Where to buy |
| Nails | $4.99 | Lowes |
| Arduino | $30.00 | Amazon |
| Breadboard | $10.00 | Amazon |
| Wires | $0.50 | Amazon |
| Resonators of choice | varies | Anywhere! |
| Wood blocks | $10.00 | Michaels |
| Servo Motors | $25.04 | Amazon |
| Female DC Power Jack | $3.00 | Amazon |
| Electrical Tape | $5.99 | Lowes |