Servo Controlling with Servo Controllers

andypugh
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19 Jun 2017 15:27 #94702 by andypugh

Replied by andypugh on topic Servo Controlling with Servo Controllers

schorsch wrote:
I think the idea around the KEB combiverts it to keep control loop between resolvers and the servo currents completely inside the controller unit. I know as well, that the KEBs can be used for the correct translation from the resolver signals into real axis-values (in mm), including the axis reference.

It is quite common to have more than one control loop. In this case here would be a velocity control loop between the drives and the motors, with the resolvers as the feedback device.
Then there is a position-control loop between LinuxCNC and the drives, with the quadrature signal as feedback.

(There are often other hidden loops too, for example most stepper drives have an internal current control loop)

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schorsch
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19 Jun 2017 17:49 - 19 Jun 2017 17:50 #94706 by schorsch

Replied by schorsch on topic Servo Controlling with Servo Controllers

Hi,
thank you very much for the clearification. I always thought PID on top PID is too slow, it seems its not.

Thank you very much too for telling me that latency is not soooo relevant for servos, I didn't know that either. But anyhow should one take the latency of the TCP-stack into accout?? I meant, TCP brings a lot of overhead, because of this it is very slow for short messages,

If not, I would always favorise an ethernet card instead of a PCI or PCIe board, its much more flexible.

Are there schematics of the MESA boards available? I do not like to use something which I do not know in detail :-)

Georg

Last edit: 19 Jun 2017 17:50 by schorsch.

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andypugh
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19 Jun 2017 17:59 - 19 Jun 2017 17:59 #94707 by andypugh

Replied by andypugh on topic Servo Controlling with Servo Controllers

schorsch wrote:
Are there schematics of the MESA boards available?

The boards are proprietary products, and schematics are not generally available. However to a large extent they are just an FPGA with pin-to-pin connections to the peripherals.

The firmware running on the FPGAs _is_ available: github.com/LinuxCNC/hostmot2-firmware

Last edit: 19 Jun 2017 17:59 by andypugh.

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