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20/06/2006
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Tom Shelley reports on controllers with unparalleled computing power to maximise productivity and anticipate trouble
New motion controllers are aimed at solving problems are at the very leading edge of research and development.
With Power PC type computing power, they are highly programmable to make life easier for researchers and those developing machine tools that can instantly change their strategy in response to feedback from sensors attached to cutting tools.
Referring to advances in controllers generally, Dimitri Dimitri, president of California based Delta Tau recently told a seminar organised by Heason Technologies that, "Physics is still the same but things are becoming much easier to accomplish now."
Delta Tau's controllers are among what is the still relatively select band to offer facilities such as a parabolic 'S' acceleration ramps as opposed to linear or sinusoidal ramps to avoid jerks. Customers include makers of equipment for laser eye surgery. In machine tools, considerable amounts of time can be saved by using a 'Lookahead' facility that allows machines to go 'flat out' down straights but on corners, automatically changes velocity so that the motion profile des not accelerate beyond set limits and remains within the capabilities of motor and machine. This capability is to be extended in the company's new "Seventh generation Power PMAC" controllers to control accelerations in an equally anticipatory manner to eliminate jerks.
These machines are described by Delta Tau as "Motion computers" rather than motion controllers since they have a Power PC type 32-bit CPU with double precision floating point capability. Native PCI, USB2 and Ethernet communications are embedded in the CPU. They give a 50 per cent speed improvement with present ASICs and a 100 per cent improvement with a new visibly large and massively powerful 'DSP Gate3' ASIC. 32 MB of Flash and 256MB of onboard RAM can be used to store large problems to support up to 32 axes and 32 coordinate systems. Next year will see the introduction of a 2GHz dual core processor so that trajectory control can be handled in one core and motion control in the other. This is expected to lead to a further four fold increase in computation speed.
In the past, the company's motion control products have been programmed in assembly language but a new compiler is efficient enough to allow programs to be written in 'C', making use of a proprietary, high efficiency math library. The Power PMAC has an open architecture and a full real time operating system based on Linux enabling responses to interrupts in less than a microsecond. Windows is presently unable to achieve such responsiveness in real time. The operating system will, however, include a full TCP/IP suite including web server and FTP facilities allowing diagnosis and software upgrading via the Internet. It will be possible to backup configurations by plugging a memory stick into the USB port. Attaching a PC to the port will make the controller show up on the PC as a removable media disk with folders that display what programs are located on the Power PMAC.
Heason Technologies
Delta Tau (UK)
"Physics is still the same but things are becoming much easier to accomplish now"
Pointers
* A Power PC type 32-bit CPU has double precision floating point capability. Native PCI, USB2 and Ethernet communications are embedded in the CPU
* An open architecture and a full real time operating system based on Linux enables responses to interrupts in less than a microsecond.
* While running machine tools at maximum speed, it will be possible to look ahead to control accelerations on corners to eliminate jerks.
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Author
Tom Shelley
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