FEATURE MOTION CONTROL Motion control


From early automation to the robots of tomorrow, motion control has become increasingly


important across the history of industry. As technology such as robotics continues to develop, the motion controller and motion engine will play an ever more important role, as Trio Motion Technology’s Dave Greensmith and Geoff Dixon explain


I


n today’s industrial engineering world, we can consider motion control as the high precision coordination of the speed and position of the


moving parts of an industrial machine. It is typically characterised by high


accuracy, often involving rapid acceleration and deceleration, and usually includes the coordination or synchronisation of multiple axes of movement. In real terms, this means applications like CNC laser cutting, through to form fill seal packaging machines, as well as robotics and other kinematic structures. To achieve dynamic and precise motion control,


movement across each axis is typically generated by a servo, stepper or precision linear electric motor. In addition, the core of any motion- based machine is the motion controller. The capability of the motion controller, as well as its programming environment, is fundamental to the performance of any machine that depends on complex motion control.


the origins of Machine control


From the industrial revolution, the first factory machinery was driven by steam or water, and control relied on revolutionary and inventive mechanical linkages, chains, belts and pulleys. Electrification, including Tesla’s development of the first induction motor in the late 1880s, progressed the factories of the twentieth century, and control capability advanced again in the 1930s with the introduction of basic electrical feedback that went on to provide early closed-loop systems. A single, large, lineshaft could


drive a machine, hard linked to rods, 52 DESIGN SOLUTIONS JULY/AUGUST 2021


cams and pulleys, and from the late twentieth century early automated control included complex logic using relays, contactors and pneumatics. Two advances around this time were the inventions of the programmable logic controller (PLC) and the variable speed drive, which began the shift to electronic control. In reality, within most factories, this technology only started to become more frequently used from the mid-1980s, and by which time many custom electronic hardware solutions for the synchronisation or positioning of machine axes were in use. The demand


from machine builders was to simplify mechanics, eliminate complexity and use electronics for faster, easier development. While a variable speed drive could control a single axis, and a PLC could control logic functions, machine builders were also looking for increased speed and accuracy across multiple axes. PLC vendors looked to provide motion add-ons, while new companies specialising in motion control began to emerge.


enter: Motion control


On the back of a shared university background, Trio


Trio’s MC1 four axis controller was combined with the capacity to


control an entire machine, just like a PLC Trio’s CSC-250


was the first computer servo controller and represented


the birth of intelligent drive systems


Motion Technology was formed in London in 1987. At that time, motion-centric projects typically involved replacing mechanical machines featuring cams and conveyors with electronic control. The objective of the first design was to develop a supervisory, central controller with an integrated servo drive. With up to three synchronised axes at 250W, the CSC-250 was the first computer servo controller and represented the birth of intelligent drive systems. The next significant development came


in 1993 with the introduction of motion coordinators that could synchronise up to four axes with pluggable daughter boards. Trio’s MC1 was combined with the capacity to control an entire machine, just like a PLC, thanks to integrated I/O and expansion modules. The following year, capability was extended with the second generation motion coordinator that could now take on up to 12 axes, again using daughter boards. The advantage of the daughter board system also gave the ability to mix servo and stepper control inside the same controller.


Multi-axis synchronisation over ethercat


By 2003, motion control capability had progressed to 24 axes by adding to the growing range of daughter boards, and controllers were able to run remote axes such as SERCOS, SLM and CanOpen. The next significant technology leap came at the end of the decade with the release of a new generation of modular motion coordinators that could control up to 64 axes of motion, with Ethernet built-in as standard. By 2010, there were various contenders for


the title of the leading Ethernet-based fieldbus for automated motion control. Based on the continuing success of EtherCAT, Trio invested in the network and the company launched its first dedicated EtherCAT Motion Coordinator.


the rise of


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