Learn more about the world's best solar car? Read more about Nuna9S hereRead more
The Nuon Solar Team’s most important goal has always been showing the world how the power of the sun can be used for a sustainable future. We do this by building extremely efficient solar cars designed to win solar challenges, such as the World Solar Challenge in Australia and the Sasol Solar Challenge in South Africa.
We can see that the future of automotive is bringing us more intelligent, autonomous vehicles. Every generation comes with new functionalities to increase driver comfort and safety. Despite that these specific things seem not closely related to sustainability, we are convinced that intelligent driving can be used as a new tool in building energy-efficient vehicles.
That is why this year, the Nuon Solar Team has focused on the design and application of high-tech technologies that optimize the way the power of the sun is utilized. We call the combination of these technologies our ‘Intelligent Cruise Control’.
On this page we’ll explain how we overcame the challenges of intelligent and sustainable driving and elaborate on how we will use Intelligent Cruise Control in the challenging environments of South Africa to win the Sasol Solar Challenge.
For 7 years now, the Nuon Solar Team has been building solar cars equipped with on-board computers. This component plays a critical role in getting the car to drive, collecting data for the strategists and showing all important information to the drivers: it makes a link between all subsystems. By sending all information to Mission Control, it enables us to learn about the way Nuna drives. In the end, it makes for a far more reliable and sustainable solar car.
Over the years, computers became smaller, yet more powerful. At the same time, the hardware and software of our previous on-board computers did not make the same leaps.
To cope with our challenges in sustainable and intelligent driving, the development of a new on- board computer was essential. That is why this year, for the first time in the history of the Nuon Solar Team, we had one man working full-time on the development of a new on-board computer. From scratch, Sjors wrote 100 A4 sheets of codebase to be implemented on a small embedded system platform being a ‘BeagleBone black’. This piece of hardware and the code together makes the new on-board computer: ‘OXII’. Sjors paid special attention to keeping the code small, simple and elegant, and to enable us in the future to build further on this on-board computer by adding new intelligent or autonomous technologies .
The relative simplicity of OXII enables us to more easily implement the intelligent driving functionalities which would be far too complex for our ‘traditional’ solar cars.
The Sasol Solar Challenge in South-Africa takes Nuna9S through challenging environments and traffic, which poses a large challenge for our strategists. Therefore, using intelligent driving to navigate more power-efficient past and between vehicles was a logical step.
To be able to do this, we needed an ‘eye’ to see the traffic and notify our on-board computer OXII about it. That brings in our radar, placed in the leading edge of Nuna9S. It detects the distance, speed, type of movement and size of preceding vehicles up to 200m. Using this information, OXII determines which detected object is a car driving in front of Nuna, by looking at its speed relative to Nuna’s own, its position and the magnitude of the reflection of radar waves from it. OXII then adapts Nuna’s speed to this vehicle and makes sure Nuna stays at a safe distance. This way, Nuna drives at more constant velocities in a very variable environment. It also brings it advantages in overtaking slow traffic or other competitors: as soon as the radar sees no slower vehicles in front of it, Nuna will accelerate quickly to its target speed.
Between having this idea and making use of it is a long, long process and hard work and everything was easier said than done; from testing the radar, to writing code to integrating the radar in our solar car.
At first, we placed the radar on our ordinary car we use to go to testing days (but also to go to the supermarket), in order to test how the radar would react in ordinary traffic. Then, we placed it on our small, wooden testing vehicle to see what kind of data and results it would produce in a more realistic ‘Nuna-like’ environment. At this stage, we made use of our old motor, battery, and a early version of OXII to create a stage which resembled a real Nuna as closely as possible.
As soon as these tests proved to work, it was time to integrate the radar in Nuna9. As carbon fibre, Nuna’s main material, is not transparent to radar waves, we did a lot of test to find materials that do. To enable an optimal aerodynamic performance we had to integrate the radar into our leading edge. Therefore we had to remove the original carbon fibre leading edge and replace it with a radar transparent material and underneath it: our radar.
Busy traffic is not the only factor in which the South Africa poses challenges on our team and car, the other one being the divers mountainous terrains with steep slopes and descents. We took this challenge eagerly to show another way of intelligent and sustainable driving. The autonomous optimization of our driving in mountainous areas, together with our Adaptive Cruise Control, makes our Intelligent Cruise Control (ICC) complete.
On a flat road, our strategists determine Nuna’s optimal target speed to drive quickly to the next control stop and not draining our battery too much at the same time. As more factors are take into account, such as, wind speeds, solar irradiation and traffic, the more cumbersome and less accurate this process becomes. Now, our software takes the factor of hills out of the equation by autonomously decelerating on ascents, which saves battery power, and accelerating on descents, which makes use of the power of gravity. It does this in such a way that the strategically calculated target speed is maintained at an average, so no valuable driving time is lost.
By driving on our Intelligent Cruise Control during the Sasol Solar Challenge we want to show the world that intelligent driving can definitely be used to save energy, and that it can bring us one step closer to a future without fossil fuels. In the Sasol Solar Challenge 2018 we want to put it to use to defend our world title.