analog position and feedback in the motion control

[Johannes_E.]

Greetings,

We are trying to use a PCI-7354 for hydraulic servovalve control.  The output, the command signal and feedback signals all need to be analog voltage signals.  We would like to generate the command signals via a DAC card or other external device.  The PCI-7354 axis voltage output is then directed to a current driver which interfaces to a Moog style servovalve.  It would be preferred to generate a user interface using Measurement Studio, or making use of the NIDAQ function library, however if we can just setup the controller in MAX that would be fine as well.  In this application there are no encoders.

I haven't been able to find the scenario in this forum, where both of the analog inputs are used for Feedback and Command respectively.  That is, we input to Axis 1 the Feedback signal on Analog Input 1 and the Command signal on Analog Input 5 and the DAC output is generated as determined by the gain settings for the PID parameters.  This configuration would then be repeated for Axis 2, 3, 4 etc.

Please let me know if this is possible, even if it would require a custom firmware modification.

Thank you,

Johannes

[Jochen]

Johannes,

what you are looking for is a combination of using the 7354 with analog feedback and electronic gearing with an analog input acting as the gear master. NI-Motion ships with several examples for gearing, so you should be able to find something similar after installing the driver. For more information about using analog feedback please click here.

This method makes sense, when you want to use an external signal to be the master. If you think of using a DAQ board to generate the master signal, you also should consider using contouring instead, as this is a more direct and accurate way to generate a custom trajectory. Please refer to the NI-motion user manual, the shipping examples and this link for more information about contouring.

Kind regards,

Jochen Klier
National Instruments