Safety & Compliance

Quick Spin: ZF’s Reax Electronic Steering System

ZF's Reax is a smart, electronic control system that takes input data from various sensors around the vehicle, including the driver, and either loosens, or tightens steering response based on what the truck is doing and what the driver needs in terms of steering inputs to do it safely

August 2017, TruckingInfo.com - Test Drives

by Jack Roberts, Senior Editor - Also by this author

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A single index finger was all that was needed to whip this Peterbilt through a Figure-8 course with ZF's Reax steering system. Photo: Jack Roberts
A single index finger was all that was needed to whip this Peterbilt through a Figure-8 course with ZF's Reax steering system. Photo: Jack Roberts

For all the angst out there concerning self-driving cars and trucks, I’ve been saying for some time that – in the early stages, at least – there will be a lot for drivers to like about autonomous vehicle technology. That’s because, if we’re talking Level 2 or Level 3 vehicle control systems (which make up the bulk of the various autonomous technologies available today), then we’re really talking about systems that are designed to work with, and compliment, a driver and make their lives a little easier, or safer, as they’re going down the road.”

ZF’s new Reax electronic steering augmentation system, showcased early in August at the company’s Commercial Vehicle Steering Technology Center in Lafayette, Ind., is a prime example of this trend. Reax is a smart, electronic control system that takes input data from various sensors around the vehicle, including the driver, and either loosens or tightens steering response based on what the truck is doing and what the driver needs in terms of steering inputs to do it safely.

Mark Cartwright, global product planning manager for ZF, noted before a test drive in mid-August that Reax is a speed-proportional control system, meaning it tightens up at low speeds and you’re cutting the wheels back and forth quickly in backing or parking operations, and it tightens it up at highway speeds when you need a better “feel” for the road and the ability to react quickly and precisely to other vehicles or debris in the road. More than that, though, Reax can look at what a driver is doing and help compensate for steering offsets to ease fatigue and increase safety.

If, for example, you’re holding constant pressure on the steering wheel to compensate for a cross wind or a badly-crowned roadway, after a few seconds of calibration and verification (around a minute, or so) the system will automatically adjust for the external forces and “steer” the correction for the driver. Likewise, the system can monitor input from lane-departure warning systems and gently “nudge” the vehicle back to a center position if it senses the vehicle is starting to wander out of its lane.

The highway attributes of the system were particularly interesting to me. But, alas, a highway segment to evaluate Reax wasn’t in the cards this day. ZF, however, had set up various cone courses behind its Lafayette facility in order to demonstrate what Reax is capable of in low-speed maneuvers, which was impressive enough in its own right.

I started out in a bobtailed Peterbilt Model 579 tractor with instructions to follow a figure 8 course around the back lot. The ZF engineer in the passenger seat had a toggle switch that allowed him to turn Reax on and off at will, in order to better showcase how the steering system works.

My first lap through the figure 8 course was with the steering system off, and it was about as standard a run as you’d expect in a modern Class 8 truck with hydraulic power steering – both hands were on the steering wheel, racking it back and forth to follow the track laid out in front of me. The second lap was with Reax engaged, and the difference was striking. With Reax engaged, I was able to guide the Peterbilt through the same course using only my left index finger to twirl the steering wheel back and forth as needed.

I worked on cars at a service station when I was a kid. Every once in a while we’d get in an older car form the 1960s when power steering was fairly new and highly over-boosted. And the Reax feel at low speeds reminded of how those cars felt back then: Quick and easy for maneuvering a big ol’ land yacht around a parking lot – but not really the feel you’d want at highway speeds. So I can see how the ability of the system to tighten up steering at high speeds would be ideal for drivers who often need very different steering responses in different driving situations. It also drove home for me how hydraulic steering systems today are essentially tuned to settings that provide the best possible, compromise, feel to deal with these differences.

Next up was a Volvo VHD dump truck set up on a straight-line course with a series of speed bumps in place halfway through the short run. Again, the ZF minder in the right-hand seat had the ability to toggle the system on and off as needed. And the goal on this run was to show how the Reax system is able to sense, react and isolate road shocks from potholes, speed bumps, and similar hazards, and keep them from affecting the steering wheel in any way.

The first run over the speed bumps at about 15 mph, with Reax off, was predictable: As soon as the steer tires hit the speed bumps, the steering wheel started jerking back and forth in response to the impact forces being transmitted through the front suspension and steering column. I wasn’t going fast enough to lose control of the VHD, but, at the same time, I couldn’t do much more than hang on to the steering wheel while it went where it wanted and compensate just enough to keep the truck moving in a straight line.

On the second run, with the Reax system engaged, things were markedly different. This time, when I hit the bumps at speed, I was able to easily hold the steering wheel straight and steady, with only a light touch from one hand. As promised, the system had almost completely counteracted the shock waves coming up through the chassis and steering column. The truck itself was jumping and jittering around just as before. But this time, the steering was almost completely unaffected by those forces.

For now, ZF is demonstrating the Reax system to fleets and truck OEMs and hopes to get the green light to enter production as optional spec or standard equipment on Class 8 trucks. And while the system isn’t entirely new (ZF has had it as an option for buses, coaches and RVs for about a decade now) my sense is that its timing on entering the commercial vehicle market is good. This is a system that complements many existing vehicle safety systems and clearly can make a driver’s job easier and safer.

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