ZF Lenksysteme helps park long trucks using a tablet

Efficiency and automated driving remain the trend in the commercial vehicle field. ZF Lenksysteme (ZFLS) is presenting innovations that make an important contribution to reducing both fuel consumption and CO₂emissions.

The electro hydraulic steering system Servotwin enables, thanks to its electronic interface, assistance functions to be provided inside the commercial vehicle. ZFLS has always focused on developments for intelligent interaction with other commercial vehicle components – because connectivity between individual systems can result in completely new functions, as the Innovation Truck proves. This prototype in the form of a long truck gives us a glimpse into the future of the commercial vehicle industry. The electro-hydraulic steering system Servotwin plus the control software for mobile end devices developed by ZF Lenksysteme are the key technologies allowing automated operation of commercial vehicles.

The Innovation Truck was a crowd-puller at the IAA in September: with precise fingertip control, a truck 25.25 metres in length was manoeuvred on the outdoor area using the app. To do so, the car parking assistant launched by ZF Lenksysteme in 2013 had been adapted to heavy commercial vehicles.

The small but important difference: this long truck has two articulation angles, as a further trailer is coupled behind the semitrailer. That makes reverse-parking of a EuroCombi ‘by hand’ very difficult in actual practice, as only a few drivers possess that skill. But with the parking app it's as easy as pie. Before starting, the operator selects in the app the required direction and speed for driving. When reversing, he touches the trailer on the tablet display with his finger and the truck starts to move. To steer, the operator simply drags the trailer on the display in the required direction, and the parking assistant automatically does the rest. Once the destination is reached, the operator takes his finger off the tablet and the truck stops moving. Forward movement operates in the same way, with a finger controlling the tractor. In practice, this parking assistant could prevent millions of euros worth of damage, sustained every year at truck depots and transport company premises.

The Servotwin is the world's first integrated electro-hydraulic steering system in series production for heavy commercial vehicles. The Servotwin is a steering system with torque superpositioning. In the first gen¬eration, this two-circuit steering system offers speed-dependent steering assistance and active centering. The new Servotwin generation additionally offers the option of driver assistance functions, which are used to improve safety and convenience in a heavy commercial vehicle. Both the demand and the possible uses for automated and partially automated driving are steadily increasing.

The Servotwin is a crucial component here, since it is the electronic interface that makes automated driving possible in the first place. This application is as yet not in use on public roads due to current legislation. At depots, however, automated driving and coupling offer several advantages at once: firstly transport companies can prevent expensive damage due to parking errors, and secondly the drivers' steering and break times are optimized, since secondary activities like coupling are automated.

Further driver assistance functions can, for example, prevent inadvertent drifting out of the lane by a corrective steering intervention or a warning signal (lane-keeping function). There is also an assistance function for use in traffic jams or slow-moving traffic. When needed, the system ensures that the commercial vehicle keeps the right distance behind the traffic in front. The driver keeps an eye on the system and can override it intuitively at any time. Side winds are a potential hazard to heavy commercial vehicles, but another assistance function compensates for these wind forces, obviating the need for the driver to expend effort countering them. The Servotwin also adapts the steering assistance to the speed of the commercial vehicle at all times.

The Servotwin has a positive effect on the efficiency of the commercial vehicle. Depending on where it is used, the Servotwin can achieve a fuel saving of around 0.6 litres per 100km compared to a conventional steering system.