Kevin Siegall, Michiba Toryu, Nikolai Tan, Sam Hawthorne, S. Taylor 

MU 2801 : Making Music With Machines (A-Term 2022)

Description

Xylocat is a robotic idiophone player designed to look like a cute cat! With the movements being controlled by 4 servos spread amongst 2 paws, Xylocat plays the xylophone by rotating the lower servo in either paw to aim towards the desired note, and then using a higher servo to move the mallet down to hit the desired key. As such, each arm has 2 degrees of freedom.

Inspiration

For this project, we were inspired by the internet meme bongo cat. We thought that the combination of a cute exterior & fun, familiar instrument would make for an appealing robotic performer. We ended up settling on a children’s xylophone as an instrument, since it fit the cute theme of the robot, and worked well with the bongo cat-esque image and paw motions.

Challenges & Obstacles

While the concept isn’t overly complicated, we did run into a few obstacles while designing the mechanisms. The first was that the foam structures used to hold the mallets had a lot of give to them, making them somewhat flimsy and imprecise. It took several iterations on them to make something that was stable enough to be consistent, while having enough give to bounce back after each hit, so as not to dampen the tone of the glockenspiel. We also had a similar issue with the way the mallets were secured to the upper servos, which caused them to slide around and out of their original positions, which we solved by marking the correct positions so that they can be accurately re-adjusted as needed.

Another issue we ran into was that, since the paws do not move side-to-side but instead rotate around an axis (the lower servos), the striking path of either mallet couldn’t exactly hit every note on the glockenspiel. We solved this by splitting the range of the glockenspiel into two, and having each paw responsible for only half of the range of notes, which was much more achievable for the range of movement each paw was capable of. The xylophone’s highest tone is out of the range currently, mostly due to the ‘sweet spot’ on the key not allowing much wiggle room for where the mallet hits, making it difficult to strike and create a tone.

Expanding on XyloCat

There are plenty of possibilities for future improvement, mainly in the realms of polishing the physical form, and optimizing the current structures to be sturdier, more reliable, more easily repairable & modular, etc. Additional features could also be added if so desired. In terms of optimization, we believe that the machine & its users could greatly benefit from having the mallet mounts be laser cut out of wood, or otherwise created out of a more sturdy material. Using a machine to create these parts would make them more precise & consistent from piece to piece, as well as quicker & easier to create and replace when new ones are needed. Regarding aesthetic improvements, creating paw-looking covers for the mallet holders similar to the main “cat head” shell would contribute to a more consistent & polished appearance. As an ambitious addition, if the paws were mounted onto two mechanisms that could slide side to side along the glockenspiel, the range issue could be solved in a way that would allow two notes from anywhere on the instrument to be played simultaneously.

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