Volvo Trucks has developed the I-See system, which operates like an autopilot and takes over gearchanging and utilizes gradients to save fuel. The I-See system harnesses the truck’s own kinetic energy to “push” the vehicle up hills. On downhill gradients the same energy is used for acceleration.
I-See is linked to the transmission’s tilt sensor and obtains information about the topography digitally. The fact that the system is not dependent on maps makes it more dependable since it always obtains the very latest information. I-See can recall about 4000 gradients, corresponding to a distance of 5000 kilometers.
I-See is an autopilot linked to the truck’s cruise control, taking over and handling gearchanges, throttle and brakes on gradients, ensuring they all operate in the most fuel-efficient way possible. I-See freewheels as much as possible - so on certain stretches of road no fuel is used at all
In this way fuel consumption can be cut by up to 5%. This figure is based on the results of simulations and tests on public roads. I-See requires use of the cruise control, and we know that on average drivers use cruise control about half the time. For a truck in normal operation, covering 140,000 kilometers a year, the saving will be about 1000 liters of fuel annually. This makes a big difference to the haulage firm’s profitability,—Hayder Wokil, product manager at Volvo Trucks
I-See carries out six different operations to utilize the kinetic energy to the maximum:
- It accelerates before the incline starts.
- If you are near the brow of a hill, the system avoids changing gear if possible. Every gearchange means a drop in speed.
- It does not accelerate when approaching a descent, but instead waits and utilises gravity.
- It starts freewheeling ahead of an approaching descent.
- It starts braking well before the downhill slope ends, but:
- It releases the brakes at the end of the slope to pick up speed ahead of a new ascent.
I-See works best in undulating terrain. With moderately long and steep slopes, I-See ensures that you can freewheel for long distances without using the engine. It is this freewheeling capability that makes the system special.
[Freewheeling] imposes high demands on precision. For instance, you have to know whether your speed will drop or increase over the next stretch of road. A gradient of just a few per cent can be the decisive factor.—Anders Eriksson, who was responsible for the development of I-See
Other factors that make a difference are air resistance and the truck’s weight. I-See will become available on the market in 2013.