Current Conditions

Bringing art, technology and climate together

Current Conditions in an elaborate ever-changing piece whose shape and color reflects the changing climate of the City of Minneapolis and the planet. The shape evolves daily and over time.

Each of the 98 chains represent the City’s weather conditions: temperature (light blue) or humidity (dark blue). The light and shape also change at every at sunrise and sunset. The intention of this work is to draw the awareness of the building’s visitors and workers to the environment of which we, as a collective local and global society, are stewards.

We are immensely proud to have been in charge of all the technical aspects of this project which required many different technical and organizational skills.

Current Conditions is a piece by Tristan Al Haddad, it is permanently installed in the Public Service Building of Minneapolis

Hardware design

This complex piece of art is composed of 98 individual hanging chains (called Orbitals). Each orbital can move its mounting point independently to hang higher or lower.

Behind each orbital is an motor and some custom-developed electronic board. Each of these boards is wired to a controller board in groups of 10. Finally, these controller boards are wired to a central computer that manage the data and sends out the commads.

We had to develop the entire mechanical and electronic architecture of this project .
On the mechanical side, we have computed the different loads and shapes for the rails supporting the orbitals, designed the pulleys and belts, chosen the motors and mechanical brakes… and much more.
On the electronics side, we had to develop and produce the power control boards behind each motors and the controller boards capable of dispatching the orders to each orbital.
We also had to take into account production, on site installation and wiring to make sure the entire piece would work as a whole.

Embedded software

The main focus of the low level software development was around robustness, deployability and maintenance.

One way we developed was to strip each microcontroller’s behaviour to its minimum and put the « intelligent » control part in the main computer so that it would be easier to modify. Electronics that are hard to access and code that is difficult to update had to be built in a way it wouldn’t require an update even if we decided to completely change the behaviour of the piece (which we did quite a few times !).

Another important aspect of our embedded software was self-diagnosis. We wanted to make sure that the piece was able to detect its own errors and hardware failures : from a broken end-switch to a noisy data line, there isn’t any unwanted behaviour that isn’t monitored and reported !

A final element that was important to us was universality. We could have added another 100 orbitals, it wouldn’t have changed our architecture or the way the system works. The same code would still apply.

Interfaces and Controls

Since this piece is ment to last as long as the building, easy maintenance is crucial.

The self-diagnosis is central for an operator to control the behaviour of the piece but it is nothing without the right interface.
Based on a node-red architecture we developed an HMI representing each element of the piece with its current health. By selecting an element, you can acces a historic of every unexpected behaviour and take action if needed.

In a few seconds, you are able to check that everything is working as expected !

IOT infrastructure

2020 was hard to anticipate, the Covid-19 crisis seemed far from representing a threat to the project in the early days. But soon enough, we realized that we would not be able to travel to Minneapolis to set up and install the whole system, so we had to be ready to monitor and orchestrate everything remotely. We quickly adapted, and upgraded the entire infrastructure to Balena in order to be able to push updates over the air, to get a direct secure tunnel to the installation, and to monitor the state of the system from Paris.

Test and Exploration

Building hardware that lasts over several years is a really difficult challenge but was essential for a piece that is part of the building.

While you can never be 100% sure, you can put the luck on your side.

We spent a lot of time sourcing the right components that had a long lifespan while remaining in our price range and responding to our specs.
We also designed all the mechanical and electronics components so that they operated well within their normal operating conditions to limit the fatigue and wear to the minimun.
But good design choices don’t always account for the unexpected, so we developped a test bench to stress test the system. For several weeks we put the differents components to accelerated aging and covered the equivalent of 10 years of operations in our lab. This process helped us improve many design choices and gave us much confidence in our systems.

As of the writing of this article, the piece has been working non stop with no error for 14 months.

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