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Positioning Systems
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VDM Laser Distance Measurement Device
Even the smallest model, the VDM18, is an exceptional solution for a
wide range of measuring and positioning tasks. It works with laser back-
ground/foreground suppression and offers an analog output. All other
sensors in the VDM Series use Pulse Ranging Technology (PRT) and
have long detection ranges, offering completely reliable measurement
results. Through the use of intense impulses of laser light, PRT offers a
high level of reliability even in extreme ambient conditions with excessive
light and dust.
Equipped with analog outputs and/or a maximum of two switching out-
puts, the sensors are used for presence checking, threshold monitoring,
the positioning of industrial trucks, measuring distances on monorail
conveyors, manufacturing systems, cranes and gantries, for stack height
control, dip monitoring, and much more.
VDM18, Laser background/foreground suppression
for short distances
The VDM18 is based upon the principle of laser back-
ground/foreground suppression and has measuring
ranges of 30 mm ... 100 mm and 80 mm ... 300 mm. The
VDM18 not only offers a space-saving housing style but
also optimal measurement accuracy. Its analog output
can be scaled to any measurement distance in the mea-
suring range. Furthermore, it is fully equipped with two
configurable switching outputs and is available with an
RS485 interface option.
VDM28, Sensing by ranging
The VDM28 is a universal measuring and monitoring de-
vice. It can be used in a wide range of industries and
applications. With its PRT-based measurement princi-
ple, it is used where sensors with background suppres-
sion have reached their limitations. The VDM28 has a
small, extremely visible red light spot and always pro-
vides accurate, reliable, clear, and reproducible results,
regardless of ambient conditions such as surface tex-
ture, dark color, or ambient light. Thanks to the Teach-in
option or the IO-Link interface for service and process
data, the VDM28 is flexible for your application.
VDM70, Distance measurement to reflector or object
The VDM70 quickly and precisely determines the
distance to a reflector (VDM70-250-R version) or to
any object (VDM70-10-L version) down to the milli-
meter. The measured values are available via inte-
grated digital interfaces. The VDM70 operates ac-
cording to the principle of Pulse Ranging Technology
(
PRT).
The VDM70-250-R is ideal for positioning transfer
cars, cranes, stock feeders as well as use in small-
parts and high-bay warehouses.
The VDM70-10-L is suitable for use in many automa-
tion technology applications that require parts to be
detected or measured over long distances.
VDM100, Further than the eye can see
The VDM100 works with perfect vision
up to 300 m. It achieves a measuring
frequency of 1000 measurements
per second using light pulses in the
range of nanoseconds.
Using noncontact technology that
is completely eye-safe, this modern
and robust device is used for fast and
accurate positioning tasks on stock feeders,
moving carriages, and gantry cranes. The Pulse
Ranging Technology (PRT) measuring method certainly demonstrates its
strengths in this area, even at travel speeds of up to 15 m/s.
The VDM100 is the perfect enhancement to the LS611 optical data cou-
pler that is already popular on the market–together these form a strong
duo to fulfill your requirements for a flexible and scalable solution for au-
tomation activities.
Distance Measurement using PRT (Pulse Ranging Technology)
A wide range of sensors with different measuring methods are available for measuring distances. However, many measuring proce-
dures are inadequate because the ambient conditions, the object to be measured, or simply the distance are not "standard."
Incorrect or inaccurate measurement results are often the result of indirect measuring methods. Examples of where this might occur
include reflective or dark objects, excessive ambient light, several objects in a beam, or the use of several sensors in one application.
Cause
Using indirect measuring methods, phase correlation, or chip-based processes generates only weak emitted light levels signals.
These technologies do not offer long-term solutions to problems.
What is PRT?
PRT is an abbreviation for Pulse Ranging Technology–a direct measuring method for distance measurement. It is the most precise industry-grade
distance measuring method.
PRT operating principles
In this most advanced of all optical measuring methods, a laser diode emits short light pulses that are reflected from the target and then recaptured by
a light-sensitive receiver element. The power of a single pulse is up to one thousand times more intense than with sensors that permanently emit light
beams. The exact distance(s) from the target is calculated using the measured signal travel time and the speed of light (c).
In modern sensors, this procedure is repeated up to 250,000 times per second.
The benefits of PRT
The benefits of Pulse Ranging Technology (PRT) lie in its direct measuring method, which achieves accurate, reliable, and clear measurements with
repeat accuracy and short response times. Only sensors with PRT always achieve accurate, reliable, clear, and repeatable results regardless of ambi-
ent and object conditions such as surface texture, dark color, or extraneous light.
Benefit from the advantages of PRT!
•
Accuracy
•
Immunity
•
Unambiguity
•
Target independence
•
Farsightedness
Introduction
