Big in the City ZF Advanced Urban Vehicle
Extremely manoeuvrable, locally emission-free, and networked with driver and environment: With the Advanced Urban Vehicle, ZF is demonstrating the potential inherent in intelligently networking individual chassis/driveline and driver assistance systems, and is presenting an exemplary solution for urban individual transport in the compact and subcompact segments.
The technology in detail
Recognized, pressed, parked: The ZF Smart Parking Assist
The system assists the driver not only in recognizing suitable parking spaces, but can also park the vehicle fully automatically in parallel or perpendicular spaces.
The parking aid obtains its information from twelve ultrasound sensors and two infrared sensors on the vehicle's front-end, rear-end, and flanks; these sensors help find a suitable parking space. The control electronics process the information and control all the systems involved in the parking function – for instance, the electric drive and the required steering angle of the electric power steering.
During the process, the driver can interact with the vehicle via the display in the cockpit or trigger the parking function once they exit the vehicle by using an application on a mobile device, e. g. a smartwatch. The Advanced Urban Vehicle then automatically searches the surroundings at walking pace for a suitable gap and automatically initiates the parking process.
Driver experience from the cloud: ZF PreVision Cloud Assist
The cloud-based driver assistance function ZF PreVision Cloud Assist provides maximum range and driving safety in the Advanced Urban Vehicle.
Unlike purely GPS-based systems, ZF's concept study not only takes into account geometry data and information on the permissible top speed, but also stores data in the cloud on the vehicle position. This for instance, pertains to currently driven speed, and lateral and longitudinal acceleration for every journey.
If the driver follows the same route again, the system calculates the optimum speed for an approaching corner on the basis of these empirical data. The assistance function then throttles back the torque early on before entering the corner, to the point where the corner can be negotiated without any mechanical braking. All of which not only protects the vehicle's battery and braking system, but also provides greater safety particularly on blind corners.
Purely electric: The eTB rear-axle drive
In the Advanced Urban Vehicle, the semi-independent rear suspension eTB (electric Twist Beam) provides the propulsion courtesy of a compact drive unit located on the left and right wheel respectively, each of which produces 40 kilowatts. With axle torque of 1 400 Nm and a maximum 21 000 revolutions per minute, the vehicle, which is tailored to urban traffic, reaches a top speed of 150 kilometers per hour.
The front axle is also highly innovative
Steering angles of up to 75 degrees enormously increase the agility and manoeuvrability of the prototype. This chassis concept reduces the steering effort substantially during parking and turning manoeuvers, and thus increases the manoeuvrability of a subcompact car in particular: Thanks to the modified wheel deflection, the turning circle diameter of the Advanced Urban Vehicle is reduced to under 6.50 meters.
The steering movements at the front axle are supported by the torque vectoring system of the rear-axle drive, which distributes the drive force individually to the two rear wheels and enables the vehicle to move off with this kind of large wheel deflection.
Communication via the steering wheel
The driver is informed of the intervention of PreVision Cloud Assist at all times. The multi-function steering wheel, which ZF uses in the Advanced Urban Vehicle, features an Organic Light-Emitting Diode (OLED) display in the steering wheel rim in the driver’s field of view. This can display a variety of information, for example, how much drive torque is reduced by the driver assist system before entering a tight bend, or provides again after the cornering manoeuver.
The driver, however, remains in direct contact with the Advanced Urban Vehicle as indicated by hands-on detection (HOD) - i.e. the capacitive system covers most of the steering wheel and detects whether the driver is in contact with the wheel. The electronic control unit built into the steering wheel converts the identified state into a digital signal and sends this to the Local Interconnect Network (LIN). Depending on the situation, this alerts the driver or activates the available assist systems.