58 / 84
Using this circuit and techniques, an
M30-diameter implementation can
provide 12 Watts of output power. The
effective power over distance is 7 mm
(Z) distance for M30. In addition, the
coupling is tolerant of misalignment
up to 5 mm.
For contactless data transmission,
the data is sent separately through
a signal converter to a 2.45-GHz
transceiver and out to a near-field
antenna (Figure 3). On the receive
side, the process is reversed.
The first variant is designed for sensor
applications and supports up to
eight PNP channels, unidirectionally
from receiver to transmitter, with
a switching frequency of 500 Hz
(maximum). Development of higher
data rates is on going, with a goal of
supporting industrial Ethernet at 100
Mbits/s.
The data connection happens upon
physical connection, and is by
necessity dynamic, occurring without
user interaction. The range is short,
up to a couple of millimeters, which
is good for security and RF emissions
purposes. The connector can
accommodate up to eight digital PNP
channels, with the current variant.
To enhance reliability, the data
link uses redundancy in the 2.4-
GHz channel, has minimal far-field
interference and the antenna design
is symmetrical to allow for rotation
(Figure 4). It’s also tolerant of
misalignment, rotation and tilt.
The full system efficiency, meaning
the efficiency of the power and data
link together, is ~ >75% (output
power of receiver end/input power
to the transmitter). Of course, this
depends on the load, the distance
and other factors, but it also includes
the losses through the data link and
PC-board assemblies.
In rugged or dangerous environments,
connectors are hermetically sealed to
IP67, even if they are not connected
with each other.
Unleash the robots
The challenge of integrating
contactless data and power translates
to relatively high cost, so the target
applications are those where the
capabilities of classic connectors have
reached their limit in terms of mating
cycles or environmental conditions,
or where the application requires
complex harness construction, and
especially for new applications, such
as connecting through walls and
materials, or connections on the fly.
One such application is robotic
systems, which are being increasingly
adapted to manufacturing and
production processes that require
greater complexity and precision.
Given the rigors of the environment
and the cost of downtime, maximizing
reliability
through
dependable
connectivity can pay dividends in the
long term.
In a typical robotic application, cables
limit the range of motion and the
constant movement and friction of the
mechanical parts also creates wear
and tear. Robots also need to move
rotationally to perform complex tasks.
Traditionally, rotation is enabled with
rotating connectors, spring cables,
or slip rings, the latter of which are
mechanically connected to stationary
rings via brushes. Cables are used to
position these copper rings in close
proximity to enable physical contact
with the carbon or metal brushes. The
brushes then transfer the electrical
current to the ring, creating rotation.
This constant friction creates wear
and tear on the moving contacts,
slip rings and brushes, which must
be replaced frequently. This results
in increased downtime and reduced
productivity.
With contactless connectors, the
deterioration of moving components
is no longer a limiting factor (Figure
5.)
Issues typically affecting connectivity
in harsh environments, such as water,
dust or vibrations, no longer impact
the reliable delivery of power, data
and signals. Contactless connectivity
can replace complex and expensive
harness constructions and slip rings,
enabling connectivity where you
could not connect before. The ability
to integrate sensors within the robotic
graspers or “fingertips” for force
feedback to the system also enables
“gentle touch” sensitivity for delicate
items.
Data to date shows that the total cost
of ownership (TCO) using contactless
connectors versus traditional solutions
is positive within the first few months
through increased efficiency, reduced
downtime, maintenance savings and
increased output.
It may be the case that contactless
connectivity will provide designers
with an entirely new way of thinking
about
mechanically
designed
machines.
References:
Connector Design/Materials and
Connector Reliability
Robert S Mroczkowski
Definition and Benefits of
Contactless Connectivity
For
factory
and
industrial
environments where dust, liquids,
and gases combine with friction,
power and robotic system wear and
tear through multiple axii of rotation,
designers need a new approach to
connectivity. This new approach
needs to be able to overcome these
many environmental and operational
challenges to secure, reliable, flexible,
and robust connectivity - for both
power and data.
The solution lies in a new
interconnection system, based
Sensors
Special Edition
58 l New-Tech Magazine Europe