Page 68 - ATZ11 November 2019 Professional

RESEARCH ASSISTANCE SYSTEMS

cept of planning adaption, which incorporates the driver intention.
The planning adaption is a new degree of freedom for ADAS design
and was introduced in [2], with [6] describing an implementation
for lateral path planning and [7] describing the concept for longi-
tudinal velocity profile generation. The planning adaption differs
significantly from previously introduced concepts like the trajec-
tory adaption [8]. The goal of this adaption is to create reference
values that fully represent the driver’s wish on future events
whereas the planning adaption aims to combine the driver inten-
tion and the system intention (the teaching goal) for a specific
Learning objective effect. Therefore, the reference values represent the overall teach-
System intention ing goal while providing a subjectively better experience for the
Driver intention driver. The planning adaption is vital for creating an appropriate
Adapted and, more importantly, subjectively individualized training experi-
ence. Aiming for tailored human-machine interactions improves
the driver’s acceptance towards the system, reducing the risk for
FIGURE 2 Lateral planning adaption (© Volkswagen) frustration and increasing the likelihood for willingness to learn.
FIGURE 2 shows the lateral planning adaption with a teaching line
adapted to the driver intention [6]. FIGURE 3 shows the core of the
longitudinal planning adaption that uses customized “g-g” pat-
10 terns to generate subjectively better velocity profiles [7].
System intention
Driver intention 3 AN ADDITIONAL DEGREE OF FREEDOM FOR
Acceleration a x [m/s 2 ] 0 The planning adaption complements the concept of the Level of
Adapted
DESIGNING ADAS

Haptic Authority (LoHA) introduced in [9] as a new degree of
freedom for tuning the control actions of the mentoring system
Race Trainer. The LoHA addresses the dominance with which the
ADAS acts on the vehicle’s interface (steering, throttle- and
brake-pedal) and therefore defines how strong the driver is influ-
−10 enced. Imitating this terminology, one can also reference the
−10 0 10
Level of Planning Adaption (LoPA) for the new degree of freedom.
2
Acceleration a [m/s ] LoHA and LoPA have different effects on the driver as they mod-
y
ify different aspects of the interaction: FIGURE 2 shows a driving
situation, in which the system intention would require a steering
FIGURE 3 Longitudinal planning adaption (© Volkswagen) maneuver to the left, while the adapted plan would require a
maneuver to the right. The LoHA then differentiates how author-
itative the ADAS would act to fulfill the selected trajectory.
LoHA and LoPA thus create a two-dimensional space for tuning
Additionally, the driver’s actions disturb the nominal control per- ADAS. FIGURE 4 shows this two-dimensional space, with lines and
formance of the internal control loops, but the active participation areas illustrating special types of cooperation. The driver intention
is necessary for the learning process. The concept for mentoring is defined as the basis of cooperation. Both axes reach from driver
systems is introduced as a possible solution for all these, at times to system, representing the respective extremes. The cooperation
opposing, needs: type maximized cooperation describes an ADAS that acts perfectly
Mentoring System means guidance, freedom, individuality and upon the driver intention. The LoHA then decides how strongly the
safety. A mentor is a highly skilled supervisor capable of demon- driver is assisted to fulfill his wish. Manual driving can be viewed
strating the teaching goal (guidance) that assists the trainee/driver as a special type of maximized cooperation with no assistance. If
with just the right amount (freedom) and continually adapts to the the ADAS is using the type minimized cooperation, then the sys-
learning progress (individuality). For potentially dangerous teach- tem intention (usually safety critical decisions which are also in
ing scenarios like driver training on racetracks, it is also important the driver’s minimal interest) is prioritized. The LoHA then decides
to protect the user from harm (safety). how strongly the driver is influenced (potentially even decoupled)
This new concept was developed together with new algorithms to prevent an undesired event. A large spectrum for ADAS design
because established approaches for implementing ADAS are not opens up between these extremes through the planning adaption.
sufficient for designing a semi-automatic mentoring system [5]. This spectrum is labeled reduced cooperation since the driver
The design of the system has to be enhanced in terms of reference intention is taken into account but not fulfilled completely.
value generation (path planning) and low-level actuation control. Reduced cooperation is the recommended type of cooperation
Additionally, the internal control loops need to take into account of a mentoring system, as it tailors the system’s interaction to the
unpredictable inputs from the user. Especially important is the user while sticking to the teaching goals. FIGURE 5 illustrates the
modification of reference value generation through the new con- tuning of the active steering assistance in the research vehicle
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