Cyclist Signals: a wearable cyclist turn signal system built on Arduino



LED turn signals embedded on a small pouch are strapped onto the user's back to wear while cycling. Traffic behind the user can clearly see left and right arrows that flash to signal a turn. The cyclist triggers each signal using buttons on the front of the straps. 


to find a current DIY design and iterate on it, contributing our findings back to the community





The story of our process

There's a cool idea that people are already working on.

There are a number of cyclist turn signal systems out there. Leah Buechley got this conversation going with her jacket that features turn signals and is built with Lilypad Arduino. There are lots of iterations on the same project out there now. I say same project because all the projects are giving a shot at the same thing: arduino + LED + turn signals for cyclists, despite the fact that they do it differently. There's this nebulous space for design conversation out there in the DIYsphere. These projects are quite different from one another, but they are all in conversation and experiment with different aspects of the design. We see our project as one contribution to an established conversation. 

You can see that these projects take on a number of forms--whether on a jacket, backpack, or mounted to the bike. The form factor is an aspect that we wanted to think more about. The constraints of a garment (the jacket or backpack) are too restrictive for the user. I don't want to bike in a hoodie during the summer in Georgia. Also, mounting the lights on the rear of the bicycle limits visibility -- it's just a matter of the small space there that makes it difficult to distinguish between signals.

So, we intended to contribute ideas about design. But also, we noticed that the current iterations are wired systems. If we could make the system wireless, we'd have more freedom with the design of form. 

So, we started thinking.

We went with this idea to build the turn signals into what we started calling a tiny backpack. It freed the user from a particular garment. It could be made with adjustable straps to wear over a backpack or over a winter coat. Plus, we'd still keep the increased visibility of putting the signals on the cyclist's back instead of on the bike. 

We also decided to build a wireless trigger system using RFID components. We were aiming for modularity and flexibility. The wireless controls could be worn on the wrist or attached to the handlebars. 

We gathered the materials:

Arduino kit & LEDs + prototyping boards + insulated grocery bag + old backpack + soldering equipment + sewing kit

The grocery bag worked well because it was relatively weatherproofed and a good size to cut down and retool to fit on the upper back. We scavenged the adjustable straps from the backpack to improvise our own. 

And we started making it.

First things first, we got the LEDs working and blinking on a breadboard. We learned about transistors while trying to power all the LEDs in a chain. But the basics worked. 

Next, we built the circuit on the prototyping board and soldered it together and installed the LEDs in a sample of the material. We were all new to soldering, but hey, how hard could it be, right? We would later learn the inconsistencies that result from newbies on the soldering iron.

It was when we were putting together the final prototype that things got really real. It was smooth sailing until we got the wire-monster assembled and then ... nothing. Just nothing. We had to tool around with the soldering to get it going. That was the most delicate part of the whole project: the wiring. But we tested it, and the show was back on the road.

At this point, I reflected on the value of the Lilypad Arduino. The conductive thread would really have made for a more durable piece as opposed to using the more delicate wiring. 

Lesson learned.

After constructing the housing pouch and straps and installing the LEDs and everything, it happened. What I knew would happen ... Nothing. Just nothing. 

Results from our investigation into nothingness: the LEDs' cathodes and anodes were touching and shorting everything. Solution: wire-tape them all to insulate them. After the fact, I learned that hot glue works better and is a lot easier.  

Lesson learned.

Rookie mistake: I misplaced the thread, and so used conductive thread, because that's what we had. There were exposed wires and that shorted the whole left side. Solution: cut out and restitch. Don't cut corners on material. It matters. 

Lesson learned.

But we got through these troubleshooting points bit by bit.

We cycled around in the dark.

It's a good day when things work.

It does its job. It triggers with a button on the straps. There's a LED indicator on the strap next to the button. They work. It fits over a backpack or a coat.  

There's things we'd do differently. There's things we learned along the way. But at the end of this, I want to iterate just one. more. time. If I end wanting to continue, all's good in my books. It's a nice feeling.

And three cheers for a fantastic team!