It’s the last day of the World Solar Challenge 2015 and quite cloudy. We are in second place, right behind our main competitor. After a neck-and-neck race for nearly four days it seems that we are going to draw the short straw. Suddenly we see them along the side of the road. By poor anticipation on the cloudy weather they drove their battery completely empty. As a result, they are now forced to remain stationary and collect energy by focusing their panel to the brightest spot in the clouds. However, the battery of Nuna8 has enough energy to carry on to the finish!
My name is Emiel Lorist, a student Applied Mathematics at TU Delft and in charge of the Strategy at the Nuon Solar Team. This means that I am responsible that our battery is not empty before the finish line in Adelaide. On the other hand, the battery at the finish must be almost empty, because otherwise we could have driven faster. To accomplish this I am constantly computing the optimal speed for Nuna during the race from the vehicle driving behind Nuna, Mission Control. With my calculations the cruise control of Nuna is set. The driver in Nuna has nothing to say in this and can focus completely on keeping Nuna on the road.
To carry out this task a good model of how the car reacts to external circumstances is necessary. How much energy does Nuna get from the solar panel? How much energy does Nuna consume at a certain speed? What is the effect of wind on the power consumption of Nuna? On the basis of this model, I can calculate the optimal speed to be as fast as possible at the finish line. The weather is a big uncertainty in this. The weather forecast is never correct in the Netherlands, this will be the same in Australia. Therefore, we take a huge variety of weather scenarios into account, in order to adapt better to the weather conditions that Nuna will face.
Suppose that the weather is cloudy and Nuna drives under a cloud for about fifty percent of the time. Then it is better to drive a little faster under the clouds and a little slower in the sun. This way Nuna gets more energy from the solar panel and still covers the same distance. Or if Nuna is driving towards clouds at the end of the day, it might be better to drive a little bit more slowly, in order to have sun during the static charging in the evening. This way more distance can be covered the next day.
Armed with all sorts of software to analyse these scenarios I will depart to Australia, to finish first with the Nuon Solar Team in the World Solar Challenge 2015.