The Water Cube

The Water Cube

The Water Cube is a permanent art installation in a small parklet at the corner of 8th Street and Penn Avenue in downtown Pittsburgh. The installation consists of a large glass cube with backlit LED walls, two drinking fountains, and two bottle fillers – one for still water and another for sparkling water. The Cube is plumbed into the city water supply, which passes through a filtration system, a chiller, and (in some cases) a carbonator on its way to the fountains and bottle fillers.

Since the commercial chiller/carbonator system is completely unattended, the Pittsburgh Cultural Trust wanted a way to remotely monitor the system to make sure it was still operating properly. They were also hoping to monitor usage of the fountains and bottle fillers; as a public art project, measuring engagement is an important metric.

The Cultural Trust and Flyspace Productions brought us in to design and install a customized Horatio to monitor both the water and lighting systems, and we ended up designing a custom lighting controller and assisting with the programming as well.

We put together a custom Horatio installation that integrates more than 30 sensors within the Cube’s water and lighting systems. It provides real-time data on the status of both systems, sending regular status and usage reports when things are working, as well as immediate alerts when they fail.

The Water System

Within the chiller/carbonator unit, we have current sensors on the main power, as well as on each of the motors and valves within the carbonator. We’ve also added an immersion thermometer in the ice bath, so we can track the temperature of the water being dispensed. There is a main flow meter on the water input to track total volume of water, flow sensors on each of the outputs so we can track usage, and high and low side gas pressure sensors on the CO2 tank.

Virtually every aspect of the water system is being monitored, so if something goes wrong, the Cultural Trust will receive an email alert from Horatio as soon as the problem arises. They can also track how full the CO2 tank is so they know when to replace it, and they can easily see how much water is being used at specific times (such as during a big festival), so they can project the installation’s future water usage and costs.

Lighting System

We were initially contracted to simply monitor the lighting system as part of the Horatio integration; there are 6 power supplies and a DMX control system, and the Cultural Trust wanted to know if any of them stopped working. We included sensors to monitor input current, output current and output voltage, which will allow us to track current status as well as power supply health over time. We also created a custom DMX sensor that tracks whether valid DMX exists and whether the DMX is changing.

Due to scheduling conflicts, Flyspace asked us to jump in and assist with programming the lighting of the Cube as well. The lighting is fairly simple – just a 4-second loop that pulses the LEDs back-lighting the walls – but they were running into some strange problems and needed someone to troubleshoot.

The DMX was only updating at about 44 frames per second, causing some stepping in the fades. Ordinarily, this should have been fine, but the scale of the cube, combined with the nearby lighting, was causing it to manifest as a “black flickering” when the cube changed brightness. This flickering was clearly being generated in the visual system – that is, it was created by the human eye and not a physical effect. We tried a few different commercial controllers just to verify that it wasn’t the controller we were using, but the problem persisted.

Our solution was to build a custom controller. There was no reason to be sending out all 512 DMX addresses, since only about 16 were being used, so we built a custom controller that sends out 16 slots as fast as possible: roughly around 500 Hz instead of 44 Hz. The increased frame rate was handled just fine by the LED drivers, and the fades became extremely smooth.

While this isn’t a solution that would work in all situations, it works fine for this application, and our involvement allowed artist Murray Horne to achieve his vision.

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