Actros moves toward smart controls
The new Actros has the system and is due here next year.
IT'S only taken a handful of years to happen, but it's sneaked up on a lot of drivers.
Car makers are also on the bandwagon with the technology, filtering down from the exclusive luxury limos to mid-range sedans and 4x4 wagons.
It started off as simple cruise control which looked at road speed and adjusted the throttle to keep the needle on the one spot. Then it was noticed that the system tended to use a lot more fuel because there was no rolling tolerance, and the system would bring in power to add one kmh to the speed.
So the makers started adding some software code so that the dumb system could let speed fade away 5-10kmh before adding throttle, and would let the speed go about the same amount over before switching off and causing full engine braking.
Over the past couple of years Mercedes-Benz and Volvo in particular have introduced a Doppler radar unit to the front of their trucks and linked that into a new system called Adaptive Cruise Control. It kept an ever-watchful eye on the road ahead and if the distance to the vehicle in front came within certain limits, the system would progressively feather the throttle, turn the fuel off completely, engage exhaust/engine brakes and finally kick in with the service brakes.
I've driven an Actros from zero to 80kmh and back to zero without touching brake or accelerator using this system.
In the Scanias, the system also talks to downhill seed control function, which will use the retarder and eventually service brakes to limit speed on the downhill run.
The development continued and the latest versions allow a driver to select the distance he or she wants between traffic ahead. In real terms, the system works on a time basis, as the distance will be automatically adjusted by the system whether you are travelling at city crawl speeds or country cruising.
With the truck sensors reading the estimated weight of the rig into the system, the computer will include estimated braking distances for the actual weight of the rig, and make further adjustments.
Allison has a system built into its auto transmission which figures out the GCM of the rig without any weight sensors. It looks at the power and torque of the engine and how much power is needed to achieve the acceleration of the rig, given axle ratios and gear selection. A host of calculations done in a split second, so the transmission can adjust the change sequencing accordingly.
Linking side radar sensors allowed the manufacturers to link lane assistance into cruise control, so that if a vehicle was intruding into your space, the system could back off the throttle and even nudge the steering away from the threat.
But one problem remained. The system still couldn't "see" down the road, so hills could only be dealt with as they happened. This was the singular advantage of a professional driver who read the road well ahead and prepared his driving style to handle it. But the latest twist goes a step even further, with the latest Actros in Europe using a system called Predictive Power Control (PPC), which includes a feed from the truck's GPS system to predict the road ahead. In short, the system knows from SatNav mapping data what the next incline is and how steep the descent on the other side. It uses this data to set up for the climb, roll over the crest and either power on or freewheel down the other side.
But that's not all. PPC also controls the transmission, selecting the right gear to start the climb and judging single or multiple gear skips to keep the rig performing at the most economical. PPC will arrive in Australia with the new Actros, due in 2013.