Page 20 - ATZ WORLDWIDE

COVER STORY AUTOMATED DRIVING

– assessment of longitudinal control top-
LKA criteria Description of the main parameters
ics: speed and distance control
Lane precision Lateral deviation to target trajectory
– assessment of lateral control topics:
Lane control quality Angular deviation to target trajectory lane keeping and lane changing
Lane usage Percentage of lane width used control.
For each driving function there was
Distance to left lane Minimum distance to lane border left
a detailed test procedure defined that
Distance to right lane Minimum distance to lane border right
allows to generate comparable and
TABLE 1 Criteria for trajectory assessment of a Lane Keeping Assist (LKA) (© AVL) repeatable results in a reasonable time
for the basic functions. It is recom-
mended to use a test track for the meas-
urements to be as effective as possible.
LONGITUDINAL SPEED CONTROL following criteria are assessed according But it is also possible to perform some
AND DISTANCE CONTROL to TABLE 3. As task it is planned to con- tests (for example for LKA experiments)
sider the traffic situation before and dur- on public roads if the preconditions are
The physical parameters needed to ing the lane change as well and to add fulfilled. All driving situations are
assess an ACC system objectively are additional criteria to those shown in detected automatically by AVL-Drive.
divided into EGO and environmental TABLE 3. All LCA criteria detailed here are The tests can be supported by a so-called
data (situation relative to vehicles ahead related to the comfort topic. Future crite- event collector to collect “sufficient” inci-
or vehicles cutting in, surrounding traf- ria will also consider perceived safety by dents in a pre-defined range of its physi-
fic situation) [5]. Research on subjective analysing the traffic situation before and cal parameters.
perception of longitudinal control has during lane change. The system behaviour of vehicle 20
shown a very high sensitivity of car (green line) that is shown in FIGURE 1 is
occupants to the braking start and APPLICATION EXAMPLE an example of a well-balanced calibra-
braking behaviour of the ACC when tion of an ACC system, there are no real
approaching a vehicle ahead at a slower The method described in the chapter weaknesses. The blue field represents
speed or when this vehicle is braking. before allows an effective grade-related the scatter band of all the vehicles meas-
Sensitivity even increases when encoun- assessment of the main driving functions ured so far in the AVL benchmark data-
tering a cut-in manoeuvre. for actual and future vehicle control sys- base, the red line is the average value of
AVL-Drive was designed to assess the tems for automated driving: all vehicles.
longitudinal control of ACC continu-
ously. Therefore the ACC ride is divided
into several typical ACC operation modes
which are, of course, strongly depended ACC operation modes Description
on the driving-ahead car (rabbit). The Follow constant speed Front vehicle is driving at constant speed
ACC operation modes are automatically Follow acceleration Front vehicle is accelerating
detected by AVL-Drive and are listed in Follow deceleration Front vehicle is decelerating or braking
TABLE 2. Based on each ACC operation Follow vehicle stop Front vehicle is stopping
modes different criteria for each opera-
tion mode were identified due to subjec- Follow drive-away Front vehicle is driving away from stand still
tive impression studies. Follow cut-in Another vehicle is entering the gap between me
and the front vehicle (→ new front vehicle)
Follow cut-out Front vehicle is leaving the lane (e. g. bending) or
LATERAL CONTROL AND my vehicle is changing the lane
AUTOMATED LANE CHANGE Running into a slower vehicle My vehicle is approaching a slower new vehicle in
ASSISTANCE front and decelerates
At the moment only few vehicles offer TABLE 2 Automatically detected ACC operation modes (© AVL)
a system for automated Lane Change
Assistance (LCA). To be sure that this LCA criteria Description of the main parameters
lane change can be done safely an envi-
ronmental detection to the rear is Lateral acceleration peak-to-peak Lateral acceleration peaks when initiating the lane
change and ending the lane change
required to detect oncoming relatively
fast vehicles in the rear that could inter- Lateral acceleration jerks Lateral jerks feel able for the occupants during lane
change
fere with the planned trajectory of the Lateral velocity Maximum lateral velocity and time needed to
ego vehicle. In this case the system complete the lane change
should not do an automatic lane change Track offset Completeness of the lane change – acceptable
and inform/warn the driver. vehicle position in the new lane
For cases where a lane change can Uniformity Symmetry and harmony of the lane change
be performed safely with the LCA, with
regards to the actual traffic situation, the TABLE 3 Criteria for trajectory assessment of a Lane Change Assist (LCA) (© AVL)
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