New, intelligent systems are needed for trucks to meet the continuously increasing requirements of road freight transport both today and in future. The ZF Innovation Truck, a joint realization of ZF Friedrichshafen AG, ZF Lenksysteme GmbH – a joint venture of ZF and Bosch – and the telematics specialist Openmatics s.r.o., shows what such systems might look like. The tractor-trailer prototype, which measures 25.25 meters with semitrailer and trailer, particularly highlights how OEMs, logistics companies, and truck drivers can benefit from the innovative integration of advanced transmission, steering, and telematics systems. The ZF Innovation Truck can, for instance, be maneuvered into the desired position remotely via a tablet app – easily, quickly, precisely, and with zero local emissions thanks to the hybrid drive. In addition, the concept presented at the IAA Commercial Vehicles 2014 for the first time has many further advantages.
"With our Innovation Truck, we illustrate the additional potential already present in our current technologies," explains ZF's CEO Dr. Stefan Sommer. "We have realized completely new assistant functions that are incredibly efficient and, at the same time, relatively simple to implement. They can also provide answers to many of the complex challenges that forwarding and logistics companies face on a daily basis."
Unpredictable waiting times at depots are one of the primary challenges. They make it increasingly difficult for truck drivers to keep their time schedules and to comply with legal regulations on driving, work, and rest times. Not least, maneuvering on the ramp often leads to expensive vehicle damage due to collisions. Especially long tractor-trailers (approximately 25m) designed for the future are significantly more difficult to maneuver even for experienced drivers: The driver must maintain a constant overview of the entire vehicle/trailer combination from the driver's seat and simultaneously be able to precisely control the movement of the rear trailer solely by steering the front wheels, i.e., the driver must perfectly coordinate the two articulation angles of the semitrailer and trailer. "The maneuvering assistant in the Innovation Truck completely relieves the driver of this steering work and much more," remarks Olrik Weinmann, project manager in Advanced Engineering and Testing at ZF and the person responsible for the Innovation Truck. "They can get out and move the tractor-trailer to the exact position required with only small finger movements and using a special tablet app."
Added value thanks to intelligent integration
The autonomously realized Innovation Truck is primarily based on three system components. The new ZF-TraXon automatic transmission system for heavy trucks is used on the input end – more precisely, the TraXon Hybrid variant, which has an electric motor integrated into the bell housing that delivers 120 kW of power and 1 000 Nm of torque. A dry clutch is installed in the hybrid module in addition. This enables all hybrid functionalities up to purely electric maneuvering. The system's high-voltage battery has sufficient capacity to complete multiple maneuvers one after the other with zero local emissions.
Moreover, there is the advanced ZF-Servotwin superimposed steering system for commercial vehicles. The ZF-Servotwin comes standard with an electric motor in addition to the combustion engine-driven hydraulic pump that provides the main power. The volume production configuration itself thus offers the potential to perform autonomous steering maneuvers with no driver intervention at the steering wheel, as is required for the remote-controlled maneuvering function in the Innovation Truck. For the engineers also to be able to realize "zero-emissions maneuvering," i.e., to provide the required steering force with the auto-ignition shut off, they specially developed a modified hydraulic pump unit for the ZF Innovation Truck. This is a purely electrohydraulic solution (electrohydraulic power steering or EHPS): Instead of the diesel engine, two ZF-Servotwin powerpacks drive the modified pump.
Not least is the Openmatics telematics application playing off its strengths in the ZF Innovation Truck. It consists of an onboard or connectivity unit, sensor technology for data recording, and special software. For the wireless detection of both articulation angles of the semitrailer and center-axle trailer for steering control as well as the relative position of the driver and the tablet to the vehicle/trailer combination, "Bluetooth Low-Energy (BLE)" tags were used: These are special wireless chips with low-energy requirements and a range of approximately 25 meters. In the ZF Innovation Truck, they are located on the back of the cab and on each corner of the semitrailer and trailer. As soon as the distance to the BLE tags or to the tablet changes, the field strength also changes correspondingly. This information is processed by the onboard unit and operator tablet.
Viewed individually, this concerns three advanced systems that set benchmarks in their area. However, a central connecting element is still needed for the remote-controlled maneuvering function. Therefore, a prototype control unit at the heart of the maneuvering assistant integrates and coordinates the individual systems previously described: It assumes the automatic regulation of the steering wheel angle and travel speed and controls the individual actuators. The latter, like the sensors, are connected via CAN bus to the prototype control unit, which itself is in constant contact with the tablet via Bluetooth. In potential volume production applications, however, the maneuvering assistant could also run on one of the component's control units, for example on the control unit of the ZF-Servotwin or TraXon Hybrid, thus eliminating the need for an additional electronic control unit.
Intuitive and safe to maneuver
The maneuvering app for the tablet is another important element for enabling the 25m truck to be remotely controlled. The tractor, semitrailer, and trailer are sketched in the middle of the tablet screen as seen from above. In addition, the possible drive positions of the automatic transmission and the selection menu for the travel speed are displayed: The operator can choose from speeds of 4, 2, or 1 km/h for forward driving and 0.5, 1, or 2 km/h for reverse driving. Once the drive position and speed have been selected by touch, the tablet user only needs to keep a finger on the front of the truck or the back of the trailer on the touchscreen, and the nearly-noiseless all-electric drive sets the unoccupied ZF Innovation Truck in motion. If they want to steer to the right or left, they only need to slide their finger on the screen in the respective direction. As soon as you take your finger off the screen, the vehicle stops automatically. The same happens if radio contact between the tablet and the Innovation Truck is interrupted.
Expanded functional diversity
In addition to the maneuvering and coupling assistant, numerous other additional functions arise from the intelligent connection of the various systems; such functions promise to provide added value in the everyday logistics routine of the future, so the vehicle data from the ZF Innovation Truck can be visualized on the tablet screen. The driver can, for example, call up the state of charge for the hybrid battery and many other parameters – even during normal driving when he/she is sitting behind the wheel. In the end, the team created a new interface to integrate the tablet seamlessly into the truck cockpit as an additional display instrument.
"From a purely technical point of view, it would also be possible for trucks at the depot to move to the loading ramp or parking position completely on their own, i.e., even without the remote control app," continues Weinmann. "This, however, requires a different infrastructure at the depots and is thus a vision for the future."