ZF’s latest steering system promises significant advances in autonomous technology, ease of driving and safety.
The ReAx platform is a column-mounted electrically assisted hydraulic steering system that can be integrated with lane departure technology. The unit uses sensors to determine driving conditions and then controls an electric motor in the steering column to provide the appropriate torque feedback to the driver.
While this makes the truck easier to drive, it isn’t ReAx’s most significant benefit. “The main driver is to offer functionalities that improve safety on the roads,” said Mitja Schulz, ZF’s commercial vehicle general manager.
ReAx helps improve safety by reducing the driver’s workload. The steering wheel requires as much as 70 percent less effort to turn in a static state, boosting driver ergonomics and reducing stress and fatigue. It also improves safety by adding a more refined approach to lane departure technology, which has been around for years.
ZF has earmarked more than $200 million for autonomous driving technologies, including software and sensors. The company currently is working with about 50 customers globally on automated driving projects, including ReAx – “an enabler of autonomous behavior,” Schulz said. But in the near term, ReAx functions more as a plug-and-play add-on for lane departure technology, including lane departure warning and ZF’s lane keep assist and lane centering control.
ZF’s Lane Keeping Assist Technology combines ReAx precision steering with a camera system to determine lane markings and provide steering correction assistance to reduce unintended lane departures and aid in collision mitigation involving lane departures. The lane centering helps keep the truck in the middle of its lane.
According to ZF, more than 30 percent of all crashes are lane departure events, and the average crash liability per truck via lane departure is $53,000.
I took a Peterbilt 579 and Volvo dump truck, both equipped with ReAx, for quick spins at ZF’s facility in LaFayette, Indiana. The ease of steering was staggering. With ReAx, I easily could turn the wheel with one finger while parked. Since the unit self-centers, you never have to guess when the wheels are straight again.
ReAx enhances maneuverability by controlling the steering system’s response, providing better positional control. The ease of steering makes it easier to maneuver in tight spaces. The system shined brighter in a tight figure-eight test when the truck glided through quick and deep left and right turns.
ReAx launched in 2006 in the RV segment. Two years later, it was added to the bus market, where TRW refined the system’s lower-speed maneuverability. When ZF acquired TRW in 2015, it widened ReAx’s scope to include over-the-road commercial trucks.
A speed-proportional control system, ReAx needs less driver input at low speeds in parking lots and tight spaces. It firms up at highway speed when you would want more rigidity in directional stability.
The learning system also compensates for road crowning and crosswinds by recognizing when a driver has to hold the wheel off-center to account for the crown or consistently strong winds. The system will take some strain off the driver.
With its ease of steering, ReAx also likely will play a strong role in driver recruitment and retention, said Mark Cartwright, ZF’s global product planning manager. “It increases the size of the applicant pool, because traditional burly truck drivers are going away,” Cartwright said.
In third-party research conducted in 2015, 97 percent of ReAx users surveyed rated its drivability as excellent. Another 88 percent said they would recommend ReAx be spec’d on their next commercial truck.