EmuLight Vest Update

Today, I’ve wrapped up the final adjustments to the first prototype vest. The vest has been tested by a couple of other people, including an elite triathlete. Some issues with the AA battery setup, and with the software and light patterns were identified, and goals have been set for the next round of prototypes.

There were two issues with the battery design: First, 4xAA is awfully heavy. Second, the batteries were mounted along with the controller board in the rear of the harness, causing the weight balance to be off. Between these two issues, the vest both tended to slide backwards during running, as well as frequently opening up the battery case and requiring adjustment mid-run. Both of these issues were addressed by switching from a hard-wired AA battery case with on-off switch to using a standard, inexpensive 2600 mAh lipstick-sized USB battery. Additionally, this is easier for an end-user since it can be charged with any standard micro-USB charger, instead of requiring a AA battery charging station.

There are 2 out of 12 light patterns that require adjustment. The “multicolored strobe” effect is too disruptive for normal running use; in a very dark setting, it makes maintaining a running line extremely challenging as the light provided is extremely variable. This mode will be adjusted to fade out only to half-brightness, to reduce the overall lighting variance. The “twinkle” mode is simply not as visually appealing as other modes, and will be replaced with a new effect.

Design considerations for the second prototypes will also include switching from a full Arduino microcontroller board to a smaller CPU-only board with a barebones minimum of circuitry. This should ideally extend battery life slightly, and more importantly, should reduce the cost of the controller board considerably, enabling the vest to ultimately be released at a more manageable price point. Additionally, the first prototype vest used permanent connections between all electronics, and permanent attachment points to the frame reflective vest. The second prototype will convert all electronic attachment points to use removable plugs, add velcro attachments to affix lights to the frame, and introduce grommets for threading through the frame. This should allow the complete removal of all electronic components and therefore improve storage and shipping reliability, and also allow for the vest to be laundered after use!

CPU frame sleep logic will be made more aggressive in order to extend operational life. Testing indicated that the CPU tended to fail prior to the battery becoming unable to supply lights. Fortunately, due to the design of the NeoPixel controllers, in this case, the lights simply “freeze” in their current position, retaining some visibility for the user.

Status: Second prototypes begun.

Road tested:Half-marathon.

Battery life: 2 hours with 1 USB phone battery.

Next steps: Half-marathon road test and second prototype

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