BART-I (Butt Eye)

Back Awareness Response Transmitter I

This interactive device makes use of 2 Infrared sensors to detect presence of obstacles from behind, particularly useful in places where you may potentially block someone’s path (narrow paths, etc). It can also be used as a defensive too for early warning of someone sneaking up on you.

How it works:

  1. Wearer will wear this like a belt.
  2. Switch to switch on
  3. If something is in the proximity of 1 of the sensor (eg. the left side), the left vibration module will start to vibrate
  4. Depending on the proximity, the vibration varies. As the strength of the vibration cannot be controlled, I only controlled the frequency of vibration in relation to the proximity. The closer something is, the more frequent it vibrates. This is similar to car reversing system.
  5. If the obstacle is in between both sensors, and both sensors pick up the obstacle, both will vibrate indicating the obstacle being in the middle. But the threshold for this is too low (I think) and as such it isn’t very sensitive.


  1. the vibration is very strong so it can be uncomfortable, and that cannot be controlled.
  2. if the wearer is leaning against the wall, it will keep vibrating. To solve this, one can simply switch it off
  3. Form not fitting, could be more flexible and concave rather than convex


Template for the form

Putting it together into a half-sphere

Trying out the sensors


Putting the IR sensors on

Putting the switch and the battery pack together

The final form!!!


Base system:

How the vibration module and IR sensor working together

This is some extra stuff I did to make the vibration not repeat itself if its within the same range for at least 1 cycle of the code. Doesn’t work well so I didn’t use it.


Multimodal Experience

Butt Bell

Eyes on the back / Back-awareness Warning

I was burnt out after a series of try-harding at making everything good because #newsemnewme, but after 2 weeks of being uninspired, I’m feeling better now and I think I’m going to go with a less tedious project.

While in my burnt out phase I made this mindmap:

I kind of broken down the types of messages there can be, as well as what forms a wearable can take. I was stuck with the idea that a notification must be from a phone.

During the lesson last week, we were introduced to the 8.5 head human figure, which allows us to accurately depict our device on a human body.

Along with the lesson, I was also told that the notification can even be something that’s outside of the mobile phone. Things like a touch or press of an object that can be translated into a vibration on another person’s forearm.

With that, I felt more at ease that there are more ideas to explore. So I started this new mindmap

Very unclear, what I highlighted are:

  • money transactions
  • water plants
  • knock on glass window
  • every website visit / instagram
  • friend proximity
  • reverse / who’s behind (eye on butt)

I found out that notifications should always be personally catered to an individual. The individual should care about the notification and not just something that is sent for a cause. As such, the ones that I highlighted are the more feasible ones (except for the one I striked out, which I included at first thinking it will be nice if it can work together with my Interactive Spaces project)

The Device


I was interested in the idea of having a sensor on the back that can detect people that are behind us. It works as some kind of rear mirror for people, a 6th sense for us to ‘see’ what’s behind us. I like it as I think it’s interesting to think of ways to enhance our senses, and wearables are perfect for that. Also, I found way too many times that I have to pull my friend when he/she is blocking someone from passing.

My idea of a wearable is going to be a belt which sends a signal to the shoulders. My rationale is that a belt will be stable and inconspicuous. The belt will also allow the sensor to always be facing the back of the person as that’s the only side of the body that it can face. The shoulder, as the vibration should feel like a tap on the shoulder to prompt the person to move away when there is something or someone behind him or her. The notification will also tell the user whether the incoming object or person is coming to the left or the right side.

A quick sketch of how this will look like in comparison to the 8.5 head model

The Interaction

So how this device should work is, if something is in the vicinity, at least 1 sensor should pick it up. The arduino will then compare both ultrasonic sensors: if one side is higher than the other, it will notify the user on the correct side. If both side detects a similar output (maybe within a certain range), both shoulders will vibrate to alert that the object or person is directly behind. The intensity will be determined by the closeness. The sound will come in the form of short beeps with decreasing intervals as the gap gets smaller, just like a car when in reverse.

Problem: if the user is leaning onto something on purpose, the device will keep beeping and vibrating. To solve this, I would make it such that the user can switch the device off at anytime, so as to prevent disruption or disturbance.

Something more advanced… If I can do it

I wonder if I can change the idea to the arduino detecting change in speed (acceleration) of oncoming ‘entities’, basically detecting change in environment so static environment will not trigger the system. This will solve the problem mentioned above. We shall see.