Truck & Off-Highway Engineering - October 2020 - 13

AUTONOMOUS FEATURE

Example of a fully redundant failsafe control system for autonomous vehicles.
the hardest part of building AI is how it deals with
situations that happen uncommonly, i.e. edge cases.
In fact, the better your model, the harder it is to find
robust data sets of novel edge cases. Additionally,
the better your model, the more accurate the data
you need to improve it. Rather than seeing exponential improvements in the quality of AI performance (a
la Moore's Law), we're instead seeing exponential
increases in the cost to improve AI systems - supervised ML seems to follow an S-Curve."
Despite such challenges, many automated-driving
technology experts continue to project commercial
vehicles as the most promising early-adoption sector
for high-level automation.

Failure detection and reaction strategy
"The autonomous self-driven commercial vehicle will
come - for sure," asserted ZF's Dirk Wohltmann, engineering director, Americas, providing a Tier-1 supplier
perspective in a recent SAE technical webinar on the
topic. But when and how it can be realized depends
heavily on the usage environment, or Operational
Design Domain (ODD), he added.
In controlled environments that can limit or eliminate
unexpected obstacles and other unpredictable vehicles/scenarios, such as mining sites, ports and industrial areas, highly automated or even fully autonomous
TRUCK & OFF-HIGHWAY ENGINEERING

CVs already can be found. But for long-haul trucking, where there's
perhaps the "biggest need and highest efficiency" potential for autonomy, according to Wohltmann, the operating environment is anything but predictable. Failure detection and the reaction strategy must
be robust and invariably reliable to instill confidence that unmanned
heavy trucks are safe for public roads.
"The system has to reliably detect gaps, sensor or other faults
and react accordingly," he said. "With increasing autonomy, the system needs to take over more and more the diagnostic and especially the reaction."
A well-defined redundant system architecture is necessary for this
strategy, and the systems must be highly connected and centrally controlled. "Each sensor, all communication lines, every controller and the
related actuators need to have a backup to take over in case of single
individual faults," Wohltmann said. Using already-available components and actuators can help save weight and complexity compared to
incorporating additional actuators. For example, active steering can
carry a backup electronic control and actuator, or it could be taken
over by the existing service brakes with "steer by brake."
Incorporating the trailer into the failsafe and redundancy concept
is vital to realizing the full potential of an autonomous-vehicle system setup, according to Wohltmann. "If today the driver might only
apply the rear axle brake as a last resort in case of service brake
failure, the automated system will integrate the front axle and trailer brakes based on 'knowledge' of performance and status and
loading setup," he said. "Experience from EBS and brake balancing
can be used for a safer and more efficient holistic braking setup
and utilized as redundancy."
October 2020 13

Truck & Off-Highway Engineering - October 2020

Table of Contents for the Digital Edition of Truck & Off-Highway Engineering - October 2020