Early cruise control systems were usually vacuum-controlled setups designed to allow drivers to set a vehicle speed and hold it indefinitely. The systems worked well on flat unvarying terrain and gave drivers a much-needed break from making constant throttle inputs.
But the systems had their limitations: They could hold the throttle at only one position, with no way to adjust automatically for changing terrain. Even worse, fuel economy often took a hit: It was not uncommon for a vehicle climbing a grade in cruise mode to suddenly apply full throttle in a futile effort to maintain the preset speed.
Cruise control has come a long way. Fleets today rely on modern interactive systems that maintain safe following distances and serve as the heart of modern integrated drivetrains, with engines and transmissions communicating and working seamlessly together to deliver the best possible fuel economy at all times.
But even at their best, many of today’s conventional cruise control systems still have a hard time dealing with changing road elevations. The most recent generation of systems rely on real-time sensor inputs, and any throttle adjustments to match upcoming hills and downgrades still have to be made by the driver.
Now, a new generation of predictive cruise control systems use real-time GPS and topographical data to logically and economically tackle any terrain. Daniel Dempsey, systems engineering manager for Cummins On-Highway, says the new systems actually are superior to a human driver.
“Drivers today can generally only see short distances in front of them,” Dempsey says. “They can effectively make speed and throttle adjustments to deal with the conditions in front of them, but they have no way of looking beyond the immediate hill or incline to set the truck up to deal with conditions out of their line of sight.”
Today’s modern systems use an electronic control module to analyze multiple data streams – horsepower, torque, engine rpms, vehicle speed, load and angle of ascent or descent – to calculate the most fuel-efficient throttle setting at all times.
