Using shape memory alloys to control sun shades

Héméra ArEx is a project that concentrates everything we love: a project that might have a positive environmental impact combined with high technical challenge and cutting edge and innovative technologies.

It was born as a PhD project that aimed to reduce the power consumption and complexity of moving sunshades through the use of Shape Memory Alloys (SMA). The project grew until the company decided to develop a full-scale technology demonstrator in the form of a shipping container.

And that is where we stepped-in! The demonstrator required several SMA actuators to work autonomously in a predefined choreography and thus, the development of the hardware and embedded software to have a smooth and reliable movement.

We also contributed to the electrical installation – made even more challenging by the use of innovative solar panels that are embedded in the sunshades – and the development of a simple user interface to operate the shades.

Hemera ArEx is developped by Arcora

Test and Exploration

Going from a PhD prototype to a full scale operationnal demonstrator is no easy feat ! And it required quite some innovation to which we were proudly able to contribute.
We helped our client to develop a test bench to better caracterize the SMA’s behaviours and added some major improvements in the design of the actuators which are now patented.

Hardware design

For Hemera we had to work with hardware on different scales.
Firstly we worked on the electronics and sensors that would allow a smooth control over the different SMA actuators. This was a challenge since the SMA require a great amount of power to heat.

Secondly, we had to size, chose and install the hardware that allowed to container to produce its own power. This meant deepening our knowledge in solar arrays, high capacity batteries and power inverters.

Finally we also became the electricians of the project and installed and connected all the light, plugs and electrical equipment in compliance with the safety standards.

All of this has put Hemera as one of our most challenging and complex hardware project so seeing it work better than expected makes us really proud.

Embedded Software

In a project requiring consequent power and mechanical loads, the control and safety were essential.

The embedded software developed for Hemera needed to precisely modulate the power injected in each of the 8 actuators to avoid overheating or moving an actuator before the others were precisely in position. It also needed to continuously monitor any of-nominal behaviour to safely shut down and inform the operator and avoid any risks.
This required a good combination of specific hardware, control algorithms and thorough testing.

Display and HMI

This container mainly serves as a technology demonstrator so it was crucial that our client could interact with it.

We developed a custom HMI using node-red through which our client can monitor the system’s behaviour. He can also setup many parameters, send orders to the sun shades or monitor errors and logs. We also added a “stress test” option were the user can configure cycling behaviours to test the long term resistance.

This really contributes to make a complex hardware and software project easy to use and to show.

IOT infrastructure

In a project with many unknowns as Hemera, we like to keep an eye on how our work is behaving even when we are not on site.
Although this was not a requirement, we have setup an infrastructure that we can access remotely over the internet.

This allows us not only to monitor long term behaviour and unexpected errors, it also allows us to remotely update all the different software components to implement improvement, patches or new features.
This is essential as Hemera relies on an interface based on node-red, a back-end developed in python – both are running on a Raspberry Pi – that communicates with the microcontroller in charge of the actuators.

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