Speed Limit Assist
Driving assistance systems
93
Introduction of the New E-Class, Model Series 212 Sedan
b
The Speed Limit Assist available as special equipment
with code (513) determines the speed limit for the
stretch of road on which the vehicle is driving. The
information is displayed in the instrument cluster in
the form of a traffic sign.
The system is activated via the instrument cluster and
is displayed as a symbol in the multifunction display.
The function of the Speed Limit Assist operates in
three main steps inside the multifunction camera.
Image recognition
The multifunction camera located at the top of the
windshield registers images of the area in front of the
vehicle.
The recorded images are transmitted to the integrated
image recognition module for which the raw camera
images and the camera control data are evaluated
while the vehicle is driving past a road sign.
The image recognition module recognizes speed limit
and derestriction signs by comparing details of the
recorded images with learned templates.
The system also takes into account speed limits that
cannot be stored in a digital road map, such as vari-
able traffic signs or roadworks signs. The image recog-
nition module assigns degrees of probability to the
registered results and forwards these on to the deci-
sion module.
Limitations of image recognition:
• Only round speed limit signs (Vienna Convention)
are recognized. Notices, such as those at the
beginning and end of some built-up areas, are not
take into account
• Image recognition is poorer in darkness, when the
signs are a long way off to one side, or when the
vehicle is traveling at high speeds
• Signs outside the viewing angle of the camera are
not detected (e.g. immediately after turning off)
• Flashing or pulsating road signs
• Wholly or partially obscured road signs
• Non-standard road signs (e.g. old traffic sign types,
incompletely covered road signs)
False alarms may occur in the following situations:
• Stickers on the rear ends of trucks or buses that
resemble speed limit signs
• Other objects that happen to have similarities with
road signs
Additional speed restriction signs are not detected,
not displayed and not recognized as restrictions, e.g.
speed restrictions applicable for commercial vehicles
only, for wet conditions, for certain time periods, for
freeway exits and advance warnings of speed restric-
tions.
National legislation governing the design and installa-
tion of traffic signs is taken into account by the
system. The image recognition module assigns
degrees of probability to all the results and forwards
these on to the integrated software modules.
– This printout will not be recorded by the update service. Status: 01 / 2009 –
