Fleet Maintenance 1220 - 34

According to Dirk Wohltmann, engineering, ZF
Commercial Vehicle Control Systems Division,
the most common signal currently used in active
braking systems is the external brake request
(XBR). Wohltmann says this type of signal is
used for ACC, collision mitigation systems, and
other systems requesting a specific deceleration
or target vehicle speed.
Though the driver must be alert at all times
and is ultimately responsible for avoiding collisions, active braking systems available today are
able to mitigate or even prevent some collisions
from happening, so it is imperative to ensure
active braking systems are inspected and maintained regularly.

Active safety system
service and repair
For the most part, keeping active safety systems
maintained is simple and straightforward. Fleets
are already familiar with inspecting and maintaining braking systems and steering systems,
and these systems should continue to be serviced
as normal.
Things get somewhat more complicated, however, when it comes to the technological components
of active safety systems. The cameras, sensors, and
ECUs that do the " seeing " and " thinking " for these
systems are more sensitive and require knowledge
technicians may not already have. While general
training can be helpful here, it is also important
for technicians to learn about the specific systems
they will be working on; details on how they function, parts and components, diagnosing issues,
repairing, and recalibrating.
While active safety system components such
as cameras, sensors, and radars should be able to
function for the life of the vehicle, ZF's Williams
notes they also require an unobstructed view of
the road, making them more vulnerable to accidental damage. In this case, the components will
need to be replaced, meaning technicians need
to know what the components do and how to
service them.
When it comes to servicing the Wingman
Fusion, technicians should start by becoming
familiar with the Service Data sheets posted on
the Bendix.com document library, says Thomas.
The Service Data sheets provide detailed instructions on servicing different parts and components
within each system.
Thomas also suggests technicians get additional
training from Bendix's video-based online training website, brake-school.com, and learn the software necessary for diagnosing the systems.
" Technicians should become familiar with
Bendix ACom PRO diagnostic software, which
is capable of providing active and inactive DTCs
(diagnostic trouble codes) on the systems, step-bystep troubleshooting actions, BUS statistics, DTC
reports, and more, " he says.
In addition to diagnosing system faults, technicians need to be able to recalibrate system
components should they require replacement
for any reason.
" Replacement parts will need to be carefully mounted and calibrated, " Williams says.

34 Fleet Maintenance | December 2020

»Automatic emergency braking systems can help drivers avoid or mitigate collisions with other vehicles
or pedestrians.
Image from ZF

" To allow the driver to completely
detach from driving, the system
would need redundancy and system
coordination in sensors and steering
actuators. For example, in a rain
or snowstorm, additional sensing
technologies could be used, such as
lidar, accurate GPS and mapping, and
V2X and V2V vehicle communication. "
Dan Williams, director, ADAS and autonomy, ZF Commercial Vehicle Technology Division

" Diagnostic software, such as WABCO Toolbox
Plus, can help in servicing and maintaining some
of these components. "
Thomas adds that technicians should attend
an in-person training demonstration of the safety technologies, if possible. Talking to other fleets
who have already implemented these technologies
can also help technicians learn best practices on
how to maintain and service the systems.

The autonomous future

When it comes to autonomous steering, the
mechanical pieces of the puzzle are mostly in
place; it is the technology that needs to catch up.
" A steering system that allows the driver to
disengage from the driving task must be robust
to all the factors that could degrade the func-

tion, and this is where the complexity enters, "
ZF's Williams says. " To allow the driver to
completely detach from driving, the system
would need redundancy and system coordination in sensors and steering actuators. For
example, in a rain or snowstorm, additional
sensing technologies could be used, such as
lidar, accurate GPS and mapping, and V2X and
V2V vehicle communication. "
Autonomous braking, on the other hand, may
require some fine-tuning both mechanically and
technologically before it is ready to take over
control of heavy duty vehicles.
" Today's braking systems use automated braking
in rare occasions as most of the braking is done by
the driver, " ZF's Wohltmann says. " But in the autonomous vehicle, automated braking deceleration,
precision, consistency, and quality are important

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Fleet Maintenance 1220

Table of Contents for the Digital Edition of Fleet Maintenance 1220