Page 45 - ATZ11 November 2019 Professional

AUTHORS

Dr. Christoph Elbers Markus Zeitter Manfred Meyer Thilo Bitzer
is Vice President Car Chassis is Project Manager Innovation is Senior Vice President of is Senior Vice President Steering
Technology at ZF Friedrichshafen Vehicle 2019 for Vehicle Motion Engineering Active Safety Systems Engineering at ZF Friedrichshafen
AG in Dielingen (Germany). Control at ZF Friedrichshafen AG in at ZF Friedrichshafen AG in AG in Düsseldorf (Germany).
Friedrichshafen (Germany). Koblenz (Germany).

nents in the innovation vehicle is han- the system steers the front and rear electric motor and pump unit with inte-
dled by the existing CAN bus system, wheels in the same direction to provide grated electronics that works as a bidi-
a private CAN that links the newly greater directional stability. rectional actuator. They can pull each
installed components, and Ethernet Additional advantages of transverse wheel upward or push it downward,
CAN connections. dynamics derive from the use of a steer- individually and actively. In this way,
mStars (modular Semi-trailing arm by-wire steering system, FIGURE 1. Since sMotion effectively counteracts motions
rear suspension) is a modular rear axle in this case the steering wheel and front with a frequency of up to 5 Hz. This
system and a central component of the axle are not mechanically coupled, the includes all pitching, rolling, and vertical
chassis concept that makes it possible to steering transmission can be freely movements that can occur when setting
connect to electric axle drives as well as adjusted based on the driving condition, off, braking, during steering maneuvers,
hybrid and internal combustion engines. or even a corrective action to the wheels or when driving over bumps in the road.
It therefore satisfies the demand of auto- that is independent of the driver can be For example, when used in conjunction
motive manufacturers for flexible plat- made. This offers new degrees of free- with AKC, sMotion prevents back end
form strategies. The ZF test vehicle inte- dom for chassis control. power slides on tight bends, even before
grates the Active Kinematics Control The vertical dynamics control the the ZF brake control system puts the
(AKC) rear axle steering in mStars for sMotion fully active damping system, vehicle back on track.
more control over the transverse dynam- which uses four actuators to adapt the The active brake-by-wire system
ics. At low vehicle speeds, this makes it suspension movements of each individ- Integrated Brake Control (IBC) is also
easier to maneuver by steering the rear ual wheel to reflect any driving situation installed, FIGURE 2. Since the IBC is a
axle in the opposite direction of the front and all road surface features. sMotion vacuum-independent, integrated system,
wheels. If the vehicle is moving faster, actuators have a very compact, external it does not require heavy, energy-con-

FIGURE 1 Cross-dynamic benefits can also be achieved by using a steer-by-wire FIGURE 2 The active brake-by-wire system Integrated Brake
steering system (© ZF) Control (IBC) is also installed (© ZF)
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