While the conventional cruise control system is useful in preventing diver fatigue, it does have its shortcomings. A new system from Daimler could be the answer, as FRANK BEETON reports.
While this column often highlights new trends in bus design and application, it is also tasked with keeping a watchful eye on developments that optimise the more conventional vehicles seen on our roads every day.
This month, our subject is Daimler Bus’s new “Predictive Powertrain Control” system, which is primarily aimed at coaches using motorways, or high-grade secondary road networks. Essentially, this technology operates in conjunction with the vehicle’s adaptive cruise control system. But, by coordinating engine and transmission management, and using controlled coasting and auxiliary brake functions, it ensures that the vehicle, at its actual operating mass, achieves optimum efficiency, irrespective of the topography being traversed.
In the central European context, the system stores pre-loaded topographical information relating to all motorways and federal highways, which enables it to accurately predict road and gradient conditions on any desired route. The vehicle’s real-time location is ascertained continuously through an onboard GPS. It can then intervene in the cruise-control process, simulating the actions of a highly skilled driver, to optimise fuel economy and performance.
The capabilities of the Predictive Powertrain Control system include:
• progressively “easing off” power at the top of hill climbs;
• accelerating to a predetermined elevated speed immediately before a climb, to prevent the cruise control from being “caught out”, and then having to apply more power (and burn more fuel) to maintain the desired speed;
• reducing driver fatigue and accompanying driving performance degradation;
• anticipatory downshifts before a climb to reduce loss of momentum;
• early up-shifting where conditions are favourable; and
• coordinating gearbox and auxiliary brake functions on downgrades.
Anyone who has driven a vehicle equipped with conventional cruise control will readily recognise the benefits that Daimler’s new system brings. Conventional cruise control is immensely useful as an aid to reduce driver fatigue, but the inability of even the most sophisticated “stand alone” systems to anticipate gradients leads to inappropriate gear changes, accompanied by short-term surges in engine speed as conditions change – all of which waste fuel.
Daimler claims that fuel consumption savings of up to four percent on long-distance coach operations are possible with Predictive Powertrain Control, which should make this system of considerable value to operators.