Page 25 - Industrial Technology July 2021
P. 25
MACHINE BUILDING
Miniaturisation means smaller,
higher performing machines
use in motion control amplifiers. It involves a traditional
copper PCB which holds the integrated circuits onto a
relatively thick aluminium or copper substrate. This layer
acts as a dielectric layer which efficiently transfers the
heat from the PCB. The MCPCB thermal transfer
technology has accelerated the power density of motion
control amplifiers and the latest generation devices
achieve results of more than 100W per cc3.
The closer the better
The more compact the motion control device, the greater
the potential to deploy it locally or embed the motor and
controller into the host machine. These embedded
controllers can take the form of cable connected modules
or an application specific control board built from PCBs or
ICs. The control advantage of these devices, particularly
those that integrate analogue sensors such as sin/cos
encoders, is more accurate signals while the reduced
length of physical communications means higher speed
servo loops. These gains are augmented for ultra-high
accuracy systems where performance is measured in nano
or picometers.
AS OEMS STRIVE TO DEVELOP EVER MORE MOBILE AND COMPACT As a result, the trend shifts closer towards the
advantage of embedded motion control solutions versus
MACHINES, THE TREND IS FORCING MINIATURE MOTION CONTROL those which are remotely mounted, especially for smaller
MANUFACTURERS TO MAINTAIN PACE. MINIATURE MOTORS AND machines requiring miniature motion control systems.
Even though the current technology may not represent
CONTROLLERS ARE ENABLING PRECISION PERFORMANCE CONTROL
significant performance gains for large machines, even for
WITH AN INCREASING NEED FOR RELIABILITY IN DEMANDING these applications a single PCB-based embedded motion
APPLICATIONS. GERARD BUSH OF INMOCO EXPLAINS HOW IN solution creates a more compact footprint compared to an
external device.
MEETING THE DEMANDS, MINIATURE MOTION TECHNOLOGY IS Cost-wise, embedded control can be less expensive
MOVING TOWARDS DECENTRALISED CONTROL. than module-based control providing a sufficiently high
volume of devices are involved, but at the same time a
he increased need for applications which are operation for some applications using control techniques new motion control device is easing the barrier to building
mobile, lightweight and compact has passed on such as electronic stall detection for stepper motors as application specific embedded control boards. Known
these same requirements to designers of well as back-EMF for Brushless DC motors. variously as an intelligent amplifier, programmable
Tminiature motion control systems. Answering However, the challenge for sensorless techniques in amplifier, or motion control module, these PCB-mountable
these demands, miniature motion solution development many uses, such as electronic stall detection, can be to devices simplify custom control board design and
has also facilitated the reorganisation of machine match the required level of reliability. This is pushing the development.
architecture, allowing OEMs to decentralise motion control trend for even very small motors to upgrade their sensors PCB-mounted motion control modules can run user
to local, embedded positions. As a result, in addition to or to include encoders where they were not previously application code, generate motion profiles, control servo
machines with highly compact footprints, this trend is used. This demand for more robust sensors has also seen positioning and drive the motor with an on-board
enabling improved performance, increased reliability and an increased trend for magnetic rather than optical amplifier. These devices can also interface via serial, CAN
helping to reduce costs. encoders, especially when deployed in harsh conditions and Ethernet. Crucially they maintain the advantages of
Brushless DC motors remain in favour for their high and medical applications. small size, measuring just 3-5cm in length and they can
power to weight ratio and their ability to generate a be interconnected, plug-and-play style.
constant torque up to high RPM. Alternatively, stepper Miniature motion control From drones to robots to patient treatment devices,
motors are frequently used in portable applications as a Whether using a motion control IC or a module, the most compact and mobile applications continue to increase in
result of their high torque to weight ratio. Despite the once significant contributor to the size reduction in electronic number while the machines themselves decrease in size.
detracting effect of a lowered effective torque because of motion controls is the performance increase of digital Along with miniature motors, motion control electronics
their tendency to oscillate, the stepper servo technique switching amplifiers. Most frequently, this means the have not only reduced in size and weight but have
has resolved the issue and uses an encoder to enable metal–oxide semiconductor field-effect transistor switch. increased in performance capability. Performance has also
higher torque across the operating range of the motor, Today, MOSFETs are reliable and compact, with significant been able to advance with the greater potential of
eliminating mid-range instability. improvements in energy losses to increase their efficiency. distributed architecture that local, embedded motion
Particularly for steppers, as motor size reduces it Another advance has been in heat flow management allows, at the same time increasing reliability with the
becomes harder to add sensors without impacting the and a new, specialized PCB, known as a metal clad potential to reduce cost.
overall footprint. This explains the trend in sensorless printed circuit board (MCPCB) is gaining prominence for MORE INFORMATION: www.inmoco.co.uk
July 2021 • INDUSTRIAL TECHNOLOGY 25