Dual loop operation using PCI7344 motion controller

[Pras]

I am using PCI7344 to control servo motor. Primary feedback to the controller comes from the motor encoder. Secondary feedback from the torque transducer is given to the ADC input. The motion controller is set to operate in absolute position mode with velocity, acceleration, Deceleration, target position values appropriately set. I expect the trajectory position to change automatically based on the torque feedback from the torque transducer. Is my assumption correct? I have referred the NI-Motion user manual, 7344 hardware manuals with out success. Any suggesions? Thanks in advance.

[algames]

In order to perform torque control using the NI-Motion Controller, you need to use the torque sensor feedback as the primary feedback. So in the axis configuration, the ADC where your sensor is configured must be set to primary feedback. You can then use the encoder feedback to work as a secondary (velocity feedback) device. Because torque does not behave in a linear fashion like position does, you will need to have several tuning schemes and apply a gain scheduling algorithm in order to properly tune the motor to maintain torque at any point of the trajectory. You can then use the read encoder function to read the ecoder position at any torque during the movement. Your setpoint and target position in the 1-d interactive will now be in ADC bit values. The 7344 contr
oller has 12 bit ADC's which means that for a sensor with a +/- 10 volt range, you will have 20/2^12 = 4096 bit counts of movement range. This means that + 10 volts will be represented as ~ 2048 and -10 volts will be ~ -2048 and so on. Keep in mind that the ADC's on the 7344 are not calibrated so you might have a little bit of discrepancy with these numbers though youn will always get the full range of the ADC.

[Pras]

Thank You Algames.

Please suggest me any documents, application notes relating to gain scheduling, tuning.