In the last year, the precision motion control market has undergone a technology shift. Machine builders and OEMs are refurbishing or upgrading machine designs with single-box ‘intelligent drive’ products, designing-in linear motors, and employing Windows platforms as front ends in ever increasing numbers. There has also been a shift towards PCIbus, and a stronger than ever take-up of fieldbus networking.
The machinery OEM
Aside from a ‘fit for purpose’ point of view, the most important factor for the OEM is reliability. Most OEMs export, yet don’t typically have a global network of support, the oness for this therefore falls on the supplier.
Because OEMs’ engineering resources are usually limited to their core market, development ease is also imporant. As systems become networked, motion control programming gets more complex. This has led to a rise in ‘canned software’ and a demand for standard languages.
The shift towards ‘single box’ control solutions integrating a drive and controller is particularly pronounced.
Almost all of this type of product on the market falls into the category of ‘positioning drives’ with software capable of simple point to point and indexing style movements. Since the space savings are considerable, it provides users with significant cost benefits (around 30%).
Machinery employing PC/Windows front ends continues to grow. With ISAbus-based PCs now harder to source, Baldor is seeing a rapid changeover to PCIbus-based controllers. Although many larger OEMs have been using PCs for years, conservatism has held back some smaller players from until recently.
However, thanks to tangible results and reduced costs, the design-in of linear motors is probably the most profound hardware shift of the last year.
Although this take-up is at the expense of AC servos, the AC servo industry is still growing at over 6%, thanks to the perception that brushless servos are ‘the technology of the future’.
Meanwhile, demand for stepper motor control axes continues to stay flat or decline slightly in the machinery and automation marketplaces, in line with the general trend to move from open to closed loop systems to enhance performance.
The trend towards fieldbus networked architectures becomes more and more pronounced. Virtually every motion controller that Baldor now ships includes fieldbus connectivity which is employed for reducing wiring on the machine, to link to I/O, man-machine interfaces, etc.
Baldor’s own choice of fieldbus – CAN and the CANopen protocol – was made largely because of the ready silicon support allowing nodes to be added at low cost. The fragmented nature of the motion controls market has meant that such a focus has been acceptable so far, but the fieldbus market is maturing and preferences are appearing — this has a knock-on effect on the motion control supplier.
The use of fieldbuses for interfacing with drives in preference to the standard and dominant ±10V analogue signal – is expected to make rapid strides over coming years. SERCOS is the current favourite network, but the technology is changing rapidly with the rise of new standards such as high speed Ethernet – and possibly USB.
On the system development side, users would undoubtedly like to see a standard motion control programming language, but the marketplace is divided into two camps. PLC manufacturers continue to move towards machine control, and among this segment there is a demand for IEC 1131-3 programming.
The trend amongst traditional motion controller manufacturers is to provide PC-compatible design options, or products with I/O facilities that allow them to replace PLCs in simple-to-medium complexity applications. Among this camp, the demand for a standard programming language is most often expressed as a preference for ‘C’.
A second trend, is the ‘open architecture’ concept that several motion control manufacturers have introduced in response to the general move among OEMs to specify off-the-shelf solutions in preference to developing their own custom hardware.
Since it is not possible to have a servo control algorithm that addresses the requirements of every machine, most volume motion control developers such as Baldor offer algorithms that are general-purpose in nature.