Next year Volvo will launch its safest car ever, the XC90. It will be a pivotal moment in the Swedish car firm's 86 year history. The original XC90, which was launched in 2002, has been a massive seller for the company.
The premium SUV is the first new car the company has produced since it was sold to Chinese company Geely by Ford in 2010. It's therefore the first vehicle entirely developed inhouse for 13 years. But most importantly to Volvo engineers, the XC90 is a big step towards the company's Vision 2020 goal, a commitment the company has made that no one will be killed or seriously injured in a new Volvo car by 2020.
The XC90 has 46 “modern” safety features, from a sensor and camera-based autobraking system to a safety cage that uses more ultra high strength boron steel. Thomas Brobergy, senior technical advisor for safety, Volvo Cars Safety Centre, says: “It's the safest Volvo ever. With this car we have Vision 2020 in sight. It's only five years away. We know it's a bold statement. But its a matter of attitude towards a serious problem.”
The car comes with a sturdy safety pedigree. Volvo is the company that invented safety glass, the three-point seatbelt and has been ahead of many other manufacturers with more modern features like SIPS airbag systems and autobraking. Brobergy says Volvo has been studying car accidents for 45 years.
The XC90 SUV is a plugin hybrid
The safety feature that Volvo is touting most heavily for the XC90 is the “run-off road” system, which will soon be standard on all Volvo cars. Run-off roads are one of the most common car accidents. The events happen at high speed and take several seconds, a relatively long time for a car accident. They are very complex because there are many different roadside environments. Spinal injuries are also unusually prevalent in run-off roads, says Professor Lotta Jakobsson, senior technical leader, injury prevention and specialist in biomechanics for Volvo. “We have seen injuries and fatalities from run-off road incidents not go down while they have reduced in other types of accidents,” she explains.
“I was looking at 95 cases of spinal injuries and many of them were run-off road incidents. We noticed that the driver would have a different type of fracture to the passengers because he is tightly gripping the steering wheel at impact. From that we worked out that a straight spine is just as important in these situations as absorbing the force of impact.”
The run-off road system in the XC90 aims to prevent spinal injuries using two main mechanisms. It first strongly and quickly retracts the seatbelt as soon as a change in the road surface is detected by a camera, momentarily before any impact. The straight posture absorbs energy from from the landing better, helping to prevent spinal injury. The seat also contains a piece of metal in the base, like a one-time only spring, that mechanically deforms to absorb vertical loads on the car occupants by up to a third, further reducing the risk of spinal injury. Jakobsson says: “The force required to trigger the mechanical system in the seat is the equivalent to a pilot being ejected from a Eurofighter.”
The simple mechanism helps prevent spinal injury
The same kind of seatbelt pretensioning is used in rear impacts and in autobraking situations. Jakobsson says the next area Volvo will focus on improving survivability for is frontal impacts, because this is the area of the car where the most impacts happen. “We can control the shoulder and lap belt retention pretensioners to prevent submarining, where people slip down the seat,” she says.
Development of the run-off road system was made possible not just by new camera and sensor technology, but also by the development of testing methods. Volvo's senior technical advisor for safety, Brobergy says: “Innovative technologies require innovative test methods. No accident is alike. For the development of the restraint system we used new methods. A robot was used to verify and get the optimum solution.”
The idea to use an industrial robot for testing the restraint system occurred to a Volvo engineer while on a ride in the Legoland amusement park in Denmark. An ABB robot was borrowed from the factory floor and programmed to move using data engineers had recorded from physical tests and real-life accidents. The robot can recreate the forces exerted during an accident on the seat precisely and is repeatable. The robot is therefore ideal for verifying computer simulations. It is also considerably cheaper than previous methods – it costs about as much as a single crash test – and has speeded up development time.
The industrial robot is used to test the effectiveness of the seat restraint
In addition to the run-off road system, 38% of the the XC90's body weight uses ultra high strength steel (UHSS), an exceptionally high amount. Henrik Ljunqvist, programme manager of body structures for Volvo, worked on the development of the XC90 and says the UHSS used is six times stronger than normal steel. He adds that the cost of the material has not been prohibitive to its use: “It's a little bit more expensive to manufacture because it is trickier to press. You only have one chance to form it. Once its been pressed it can't be heated enough to press again.”
“The strategy for the energy management and how to take care of the loads in the car happens very early in the design process. We look at each component and evaluate which material to use, it's a massive job.”
Ljunqvist says that passive safety features, such as the use of ultra high strength steel, the safety cage and deformation zones in the body, are crucial to automotive safety and will not be superseded. “Even with the active safety systems, the cameras and sensors, you still have to protect the occupant,” he says. “Autobraking can reduce the energy in the crash, but you still have to deal with deformation and the safety cage.”
A “substantial” part of the company's R&D budget is spent on the development of new safety features. A lot of that money is spent at the Volvo Car Safety Centre in Gothenburg, where engineers develop and test safety systems. The centre, which has around 100 full time engineers writes off around 400 cars each year.
The XC90 uses a high percentage of boron steel for extra protection
The XC90 is going through the last of around 65 physical crash tests at the Safety Centre, several of which have been to physically verify the performance of the run-off road system in different scenarios. One of the last to be performed is the “ditch test”. The car, which is painted bright orange and has marks on it to aid post-impact analysis, contains three dummies, two adults and a child to represent a family. It is fitted with accelerometers and gyrometers along the bottom and in the seal of the roof to measure force and speed. There are also sensors fitted in the dummies and the seats to measure the vertical loading on the dummy and the running of the road, to allow for the bumpy contact of the road and the impact.
For the crash test the car's speed is built up to 80 km/hr and released into the ditch, which launches it through the air into a dirt bank.
Jan Ivarsson, deputy director of the Volvo Car Safety Centre says: “After the impact engineers will look in particular at the footage of the inside the car to assess the electrical seat belt retractor and how it affects the driver. It should be operating just moments before the crash. They will also examine how the airbags and curtains operate. In this case the curtains may have operated because the car has detected a side impact or a roll over is about to happen.”
Cynics would argue that just like other car firms, Volvo has sales targets and its brand means a goal like Vision 2020 is necessary. That after years of foreign ownership, a commitment to eliminating deaths and serious injury from your cars is a reaffirmation of corporate direction. However, it's difficult to be cynical about such an admirable goal and attitude, especially when such a strong commitment to safety is apparent in Volvo's research and development process and its engineers.
Alongside the target of zero deaths by 2020, it's reported the company has a sales target of 800,000 cars a year by 2020, an increase of around 100% compared to the last decade. It will be interesting to see if it can achieve both.