Intelligent being. InnoDrive from
It’s not often that a passenger rises to the level of a rally-style codriver. The ideal codriver is there whenever you need them—authoritative, but not bossy. They know the terrain like the back of their hand, warn you in time of sharp turns, or give the all-clear to floor it when the road permits. If desired, a codriver just like that is available at any time in the new
Thanks to highly precise navigation data, the comfort assistant not only knows all about the route and speed limits, but also knows the exact topography (i.e., the elevation profile, corner radii, and gradients). Using this information, it continuously calculates the ideal driving profile, selects the optimal gear, and initiates acceleration and braking. The double-clutch transmission is integrated and controlled in a forward-looking manner. The result is a drive that is not only noticeablysmoother than when the driver operates the gas and brakes, but also more efficient and often faster as well.
Philip Markschläger knows InnoDrive as well as anyone. As the project manager, he was in charge of the development of the system. “You have to take the plunge with InnoDrive, for starters,” he says, lifting both feet from the pedals as the dark-blue
A trinity of speed, efficiency, and comfort
The question Markschläger and his team asked themselves at the outset of their work was what the optimal acceleration is. Is the ideal acceleration one that provides for high average speeds? Or is it acceleration that minimizes consumption? Or is it when the car’s occupants feel especially comfortable? Somewhere between these three parameters—speed, efficiency, and comfort—lies the solution for optimal acceleration.And that solution looks considerably different than one’s intuition might suggest.
Flashback to May 2011, south of Berlin, at the Challenge Bibendum. The competition was established to promote sustainable mobility solutions, and
Millions of options—and a single optimal one
The additional variables are provided by the route: gradient and curve radii, straightaways and city boundaries are all read from high-resolution navigation data while a camera also reads speed limit signs, etc. The current wind and rolling resistance go into the calculation as well, and continuously feed the system with information. Last but not least, InnoDrive responds to every steering maneuver by the driver and adjusts its planning accordingly, as in the spontaneous lap of honor around the roundabout.
Roughly two times a second, the control unit provides an update: a completely recalculated version of the driving profile and the ideal trajectory for the next two miles. InnoDrive selects from countless transmission states (eight gears and coasting) and determines countless acceleration options. “This continuously gives us millions of options for the driving strategy,” says Markschläger. But the computing power required for this is immense. So, along with his team, he adapted the dynamic programming computing method—an optimality principle developed by mathematician Richard Bellman—until it could support real-time capability in the car. “Essentially, the idea is to recognize at an early stage which paths cannot possibly lead to the optimal solution,” and then to discard them without running through the whole calculation.
Meanwhile, Markschläger has guided the
Normal vs. Sport
That’s not all InnoDrive can do. On a country road, Markschläger flips the switch on the steering wheel to Sport and suddenly the codriver’s sporty side side surfaces. The
Markschläger switches back to Normal mode. Now the
By Bernd Eberhart
Photos by Christian Grund