Beat Boxer

Team Synesthesia

Creating music through physical interaction with the punching bag

Beat Boxing is a physical interaction installation that is modulating music through boxing and body movement. It is to provide people with a brand-new way to create music and help them to release stress through exercise. This design combines music and exercising, enhances the user’s pleasure from modulating music and improves the user’s well-being.

In its simplest terms, the Beat Boxer is a punching bag that will play an assortment of musical sounds that, if interacted within an organized manner, can create a musical representation of one’s current mood.

Physical contact is the main interaction form. The Beat Boxer makes different instrumental sounds when one strikes the bag with any part of the body. The Beat Boxer has an assortment of sensors that are placed in commonly struck areas when boxing. So, a sensor where a person may throw a jab, hook, low hook. To illustrate this point, please refer to the first image (front view of the bag) below.

Technical Description

The physical form of the project is an ordinary punching bag from the outside (with fabulous paintings from Mia), but with some "brains" inside connected to a computer via USB.
To add so-called "brains" to the bag:

  • we designed Load Cell Pouches,
  • put load cells into the pouches,
  • covered and glued them with a yoga mat,
  • glued that to the inside of the punching bag,
  • protected electronics with a plastic box and put it inside the bag,
  • and refilled the bag with something like memory foam and small sandbags.

When you punch or press the bag at the designated place - where the Load Cell is, the HX711 Module, with the help of Arduino HX711 Library and some code, converts its output to an aggregate weight value - grams. Suppose the value in grams is higher than or equal to a specified value (i.e. 1000 grams). In that case, Arduino will press and release a key on a keyboard, which will trigger Unity 3D to output a sound byte assigned to this key.

There are five load cells, each representing a different "instrument": claps, hats, kicks, snare and woods. Each instrument has three sounds: light, medium and heavy, activated by 1000, 2500, and 5000 grams punch, respectively. So, in total, there are 15 different sounds.

To centralise the system and connect all load cells soldered to HX711s, we used Arduino Leonardo. We have chosen the Leonardo because it has enough output pins for our purposes and a micro USB connection. Micro USB connection meant that we could connect the Arduino Board to a computer and access the computers keyboard. This saved us time and provided us with a backup solution - activate sounds via keyboard presses if something broke during the exhibit.

Final Statement

As it is, the final exhibition went well for everyone in the team. However, there are a few things that should be brought up about the final product produced. At the beginning of the day, our team had an issue with the two sensors located on the right side of the bag. This issue was that the sensors would activate and then stay activated and repeatedly play sounds into the output. To hotfix this, our team opted to smoke and mirrors this issue by disabling the two sensors from making sound and manually playing an appropriate sound byte through a laptop when the bag was struck. Now, this hotfix was more useful than we thought.

At the beginning of the event, our team had the three sensors working properly, but an issue occurred as the tutors began to test our product. So our physical connection to the bag got disconnected. This wasn't the wired connection to the bag from the Arduino but the pins on the Arduino board to the pressure sensors. To fix this issue, instead of halting the exhibit, our team opted instead to generate all of the sounds through the computer to still deliver a satisfactory experience.

As for feedback, Chenlei did some great graphic designs for the brochure and poster, which included a QR code to a survey that people could take after testing the bag. The responses were mostly positive and liked the idea. Also, conversing with people testing the bag often lead to positive reactions and comments. Looking at the facial expressions of users hitting the bag would often lead to a smile after realising the bag made a sound after being hit, and people would then continue hitting the bag after to test other sounds. So in terms of public response, it felt like it achieved the purpose of at least providing fun for the users and a satisfying experience of modulating music through action.

Moving forward, our team all agree that it would be best to start from scratch with the development of the punching bag. The main issues with the bag are as follows:

  • the wooden plates for the pressure sensors not being flat and not activating due to padding and curvature of the bag,
  • pressure sensors being unreliable and delayed,
  • the wire setup bumping each other causing false signals being sent,
  • code that recognises multiple inputs being sent and overlapping many sounds through the speaker.
These issues would be best fixed early on in the design process and could have led to more satisfactory results. So the next steps would be to address these issues and perhaps have a raspberry pie inside the bag to avoid all the cables and reliance on a computer to operate.

All in all, while the final product created broke halfway through the day, our team managed to provide an immersive experience to an audience.
After all, a broken clock still works twice a day.