Volvo Trucks is adding a new driver-assist steering feature to its 2020 model-year line-up. Volvo Dynamic Steering is an electric-over-hydraulic steering-assist system designed to improve maneuverability and lessen driver steering effort by up to 85% at low speed while maintaining a stiffer feel at highway speeds. VDS is also said to reduce driver fatigue through reduced steering effort while reducing road-shock transmitted through the steering column and steering wheel to the driver.

VDS is an active steering system that uses an electric motor mounted on top of the hydraulic steering gear. The motor provides additional torque when needed in the steering effort, but it also helps absorb and mitigate steering column torque originating at the wheels. Drivers will immediately notice the absence of shocks and abrupt wheel movement when driving on rough surfaces.

Volvo believes VDS will help reduce driver irritation and injuries resulting from repetitive strain associated with traditionally stiff steering and shock loads at the steering wheel.

"Drivers are the trucking industry’s biggest assets, and opportunities to increase driver recruitment and retention are top-of-mind for our customers," said Chris Stadler, product marketing manager, Volvo Trucks North America. "Providing state-of-the-art features that improve drivers' physical working conditions and comfort is an important aspect of driver satisfaction, as well as increasing overall productivity and road safety."

First launched by Volvo Trucks in Europe in 2013 (and the subject of viral videos like The Epic Split), VDS is ideal for diverse and changing terrains and automatically adjusts to handle any roadway condition. From rough roads to tight maneuvers in urban environments, VDS can help drivers navigate unexpected situations such as potholes and rapid tire deflations. It provides up to nine ft.-lb. of torque in the steering column.

VDS had to be adapted for North American trucks from the European cabover trucks with their unique steering geometry and heavier axle loads.

VDS is not an active steering system. It will not steer the truck – merely assist the driver in doing so. Stadler told reporters the VDS mechanism could be a stepping=stone to active steering functionality such as lane keeping assist and lane departure prevention, which will likely be added at some later date.

Should the system fail or malfunction, the steering reverts to standard hydraulic steering in the absence of the electric assist. Drivers will also get a notification in the driver display alerting them to the status of the system.  

"Nothing with VDS short of a hydraulic system failure will disable the truck or put it down," said Stadler. "The truck will be completely safe to operate without VDS and won't force any unnecessary downtime."  

With more controlled steering, VDS also helps reduce operational fatigue by filtering road vibration and noise that comes up through the steering wheel. Repetitive motions due to varying roadway conditions and maneuvering actions could cause physical discomfort, which can be lessened when using this system. In fact, testing has shown that VDS has the potential to cut muscular strain by up to 30% and for some specific motions, strain can be reduced up to 70%.

“With the VDS system, we see increased productivity for our customers and decreased fatigue for drivers," said Stadler. "In addition, it contributes to improved stability and control of the vehicle, thereby increasing road safety.”

Key VDS features include:

• Vehicle Stability Control leads to increased directional stability on the highway, which offers a more relaxed and safe driving experience with full control at all speeds.

• Return-to-Center, or Zero Return enables the steering wheel to return to the center position when the vehicle is in motion, making it easier to reverse the vehicle and maneuver in tight areas.

• Dampening allows the steering system to filter inputs from the road surface and, based on feedback from multiple sensors, helps improve handling and vehicle stability.

• Lead/Pull Compensation provides a torque offset within the steering system to compensate for crowned roads, steady crosswinds and other short-term conditions that can affect handling.

Quick Spin

Following a technical discussion where VDS was introduced, editors had the opportunity to drive trucks equipped with VDS on the test track at Volvo's Customer Center in Dublin, Virginia.

The system could be switched on and off for demonstration purposes, but it will be always on in real-world service and utterly transparent to drivers.

At low speed, the steering is car-like and the wheel is extremely easy to turn. It stiffens up as speed increases to a point where the VDS is probably not contributing at all to the steering effort. While backing, the system will self-center the wheels (something truck steering will not normally do) to aid in steering precision.

The demonstration included a trip across a series of off-set bumps. Without VDS the steering tugged hard right and left as the wheels rode over the bumps. With VDS on, the bumps couldn't even be felt.   

VDS dramatically reduced the effort required to turn the steering wheel at low speeds, and nearly eliminated the shock and vibration felt through the wheel by the driver.  

Volvo will start taking orders for Dynamic Steering beginning in this fall. It will go into production in April 2020.