The Nissan Leaf was fitted with a GPS, eight laser scanners, seven cameras and radar systems located around the vehicle, these were all connected to six electronic control units in the trunk. The Leaf traveled alongside motorists on country lanes and motorways from Nissan's technical center in Cranfield, Bedfordshire, to its manufacturing plant in Sunderland, where it was created.
The automaker said that the advanced positioning in the Leaf allowed it to assess its surroundings and made decisions about how to navigate roads and obstacles. During its 230-mile journey, it traveled on different types of roads and alongside traffic, from country lanes to the M1 motorway.
It also had an autonomous technology that was activated along the route whenever the vehicle needed to stop, start or change lanes.
The project, known as HumanDrive, aimed to develop an autonomous vehicle control system. It was funded by the British government and an industry consortium of nine partners, including Nissan and Hitachi.
"The HumanDrive project allowed us to develop an autonomous vehicle that can tackle challenges encountered on U.K. roads that are unique to this part of the world, such as complex roundabouts and high-speed country lanes with no road markings, white lines or curbs," said Bob Bateman, the project manager for Nissan's Europe technical center. (Related: Self-driving cars could easily turn into self-crashing cars that deliberately target and kill humans, expert warns.)
Several safety measures were put into place to make sure the car did not cause any accidents. These measures include regular breaks to assist the asses the risks the car would face over the route.
Two engineers also remained in the car through the journey to take control if necessary. For instance, the human drivers briefly took over the controls when the car pulled in at service stations to charge its battery.
Nissan's research and development head in Europe, David Moss, said: "Other drivers around the vehicle would not have noticed that the vehicle is actually fully autonomous. The vehicle is much more aware of what is happening in that surrounding area than possibly a driver would be because of the amount of sensors which are continually monitoring the environment."
The British car industry has promoted economic opportunities of developing self-driving cars, as it can produce a £62 billion economic boost by 2030. It also believes that Britain has significant advantages over other countries in pushing these autonomous vehicles.
However, driverless car trials have caused some concerns for the safety of road users. Uber, which has been testing its self-driving cars in the U.S. paused its trials in March 2018 after a vehicle in autonomous mode killed a woman in Arizona in what was said to be the first reported fatal crash involving a self-driving vehicle and a pedestrian.
Nissan points to the length and the complexity of Leaf's journey as evidence that the safety concerns could eventually be addressed.
Junior business minister Nadhim Zahawi said: "Safely completing the longest autonomous drive in Britain is an incredible achievement for Nissan and the HumanDrive consortium, and a huge step towards the rollout of driverless cars on UK streets."
The team that helped develop Leaf's self-driving skills compiled a comprehensive data set of previously found traffic problems to let the car's machine learning system develop strategies for coping. Before testing the car on public roads, the team also put it through months of testing, first in computer simulations to test its decision-making capacity, and later on, in private test courses.
It remains unclear whether self-driving cars will hit the streets for general public use, but the government says its priority is to facilitate the safe rollout of more advanced self-driving cars when the sector is able to do so, said Moss.
"You’re not going to see all of this tomorrow in a vehicle. But what you will see is elements of it progressively come in ... over the years."
Learn more about autonomous driving at RoboCars.news.