2023 World Solar Challenge entrant welcomes clouds – not the fluffy white ones

Solar roller on Australia-spanning race packs an Nvidia Jetson, radio link to an AWS edge box, and Starlink uplink

Special Projects Bureau Revisited Long-time Reg readers may recall that in 2011 and 2013 The Register's Special Projects Bureau followed the World Solar Challenge – an event that sees solar-powered cars cross Australia from north to south over 3,000km of roads and some of the planet's least welcoming environments.

At least, they're not very welcoming unless you are running a solar car that needs reliable sunshine.

The starter's flag for this year's edition of the race drops on October 22, and The Register last week learned that University of New South Wales's (UNSW) team in the race has become very fond of clouds.

Hyperscale clouds, that is – not the fluffy white things that solar rollers detest for depriving them of energy.

UNSW's entrant in this year's Challenge is again named Sunswift and will contest the "Cruiser" class for vehicles that look a lot like normal, boring, passenger cars.

In conversation with professor Richard Hopkins of UNSW's Faculty of Engineering, and Sunswift Racing technology manager Josh Bramley, we learned that this year's UNSW-mobile will pack around 100 sensors, all connected over a CAN bus to a box running an Nvidia Jetson System on Module (SOM). Connecting all sensors to a hub replaces the distributed network architecture used in previous vehicles.

World Solar Challenge contenders are low to the ground and not easy to spot, so they roll down the road accompanied by two escort cars. Sunswift takes advantage of their presence by including Ubiquiti Airmax point-to-point radios so that data can stream from the Nvidia box to an AWS Snowcone device in one escort.

Snowcones are rugged servers about the size of a shoebox that include storage and can run VMs or AWS services. Sunswift Racing will run Greengrass, the Amazonian IoT device manager and data cruncher, to analyze the car’s progress.

Bramley told The Register Sunswift intends to mount a SpaceX Starlink terminal in the escort car so it can upload data all the way to the cloud and perform more detailed analysis.

All that tech matters, because the rules for this year's challenge require Cruiser class cars to traverse 1,195km without connecting to the grid to recharge batteries. Top-ups with external solar panels are allowed, but that's only possible for a few hours each day – between the 5:00PM deadline to leave the road and sundown. And of course all cars in the Challenge are coated in as many solar panels as they can manage to ingest energy as they roll.

Sunswift Racing has already driven 1,000km without plugging in during a trial, and during the last Challenge managed the 1,195km stretch.

But while the Challenge's name suggests friendly competition, the event is a race. UNSW intends to take just five days to cross Australia and win its class – maybe even the whole event.

To do that it will need to go faster than its pace during previous Challenges – even during the long stretch between power points.

The tech aboard Sunswift therefore allows the team to determine the optimal speed at which to travel while preserving power. The team can limit the car's speed – so that even if the driver floors it, the car won't do anything to ruin the energy consumption plan designed to achieve the best result for the day's driving.

Those plans include the impact of passing maneuvers, which are tricky because they require passing both a solar racer and its two escorts. Enormous acceleration may see Sunswift reach clear road, but the sensors and analytics mean the team can also assess whether a little drafting is advantageous before passing under better conditions – such as on downslopes – in the name of saving energy.

Speaking of which, the Nvidia box and associated infrastructure have an energy budget of 15 Watts – a resource that could be used to keep Sunswift rolling.

But Bramley said that 15W more than pays for itself, because the energy savings the Sunswift rig finds exceed consumption.

This year's Sunswift has another important addition: course credit.

Professor Hopkins told The Register that the racing team was previously a volunteer effort and crew signed up after students cajoled their colleagues into coming along for the ride. He's since put Sunswift on the curriculum, which means more team members.

The Register's experience following the Challenge leads us to believe signing up for the Sunswift subject is probably the best decision UNSW students will ever make! ®

Bootnote: No, we don't plan to follow the race from the road this year. The food is terrible out there, even dusty flophouses aren't cheap, and fuel costs are exorbitant. Also, two treks across Australia were probably enough – and we have work to do back home, from where we'll keep an eye on the 2023 Challenge.

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