actions can be minimized by introducing
smart designs and choosing a play-reduced actuator design. As an example,
an actuator play of only 0.5 mm can
result in play of up to 5 mm at the end
of the table, depending on the levers
evident in the equipment.
Confirm speed ranges. Lifting speeds
of procedure chairs (Figure 3) and
surgical tables should not be too slow
to reduce treatment time. Speeds for
pillars in procedure chairs typically can
reach up to 35 mm/s, while speeds for
operating tables can be slower at 15
mm/s. Speeds for actuators involved
in functions other than lifting can be as
slow as 5 mm/s to 10 mm/s, since these
usually are designed to perform a turning
function by pushing a short lever.
Reduce noise levels. The noise level of
electromechanical actuators is generated
by a combination of the electric motor,
gear, and screw design. Designers can
reduce noise by specifying actuators
with slower-turning motors and worm
gears, and by introducing noise-damping
covers, among other measures.
Figure 2: Telescopic pillars are able to achieve a high stroke to retracted height ratio,
which is particularly relevant for surgical tables.
Figure 3: OEM designers can reduce risk
and speed time-to-market by considering
complete actuation systems in which all
components have been tested and validated
Technological advances in actuators and
pillars have extended to their control
units, which have continued to evolve in
terms of functionality and connectivity
for patient positioning applications.
Controllers can be configured to manage multiple actuators and pillars, and
integrating microprocessors can manage
position control, speed, synchronized
movement, dependency between actuators, and safety stops, among other functions. Input devices (hand switches, foot
switches, and wireless switches), external
limit switches, and other safety elements
can also be managed using appropriately
specified control units.
Controllers can also be equipped to
recall memory positions, allowing for
quick setup of frequently required setups,
such as a “home” for returning a table
back to a basic starting point for the next
On the horizon, innovations in the
world of electromechanical actuators
and pillars promise to elevate functionality, performance, and reliability.
These include increased connectivity
capabilities, condition monitoring to
assess the health of the systems for
timely service calls, and wireless input
via smartphones, among many other
As with the mechanical system
components, medical controllers should
be certified according to IEC 60601-1
to ensure maximum electrical safety for
the patient and operator, and to reduce
development time and risk for OEMs.
Where to Begin?
OEM designers can get a big assist—
reduced risk and faster time to market—by
considering complete actuation systems
in which all components have been
tested and validated together (Figure 3),
and are UL certified in accordance with
IEC 60601-1 medical safety standards.
Ultimately, partnering early in the design
stage with an experienced manufacturer
can help keep any actuation application
moving in the right direction. MDT
Thomas Lotz is Business Support Manager
for SKF Motion Technologies, Inc. Contact
him at email@example.com