PCI7344 and Copley Accelus Drive

[jspaarg]

Has anyone used this combination?

I am having a number of problems (which I believe are primarily the amplifiers).

[allen_h]

Hello jspaarg,

I have not used this particular combination before.  Just curious, what problems are you having?

Allen H.

[jspaarg]

I am using four amplifiers; three are on linear motors, one on a ball screw.

Two of the four linear motors drive the parallel tracks in an H-Bridge (X and X')

The third linear motor drives the crossbar.

The crossbar motor continually "drops out"; i.e. it gets following errors and will not restart.

The parallel motors seem to build up tension even though they report being at the same position.

The ball-screw works fine.

[allen_h]

Is this motor/drive a servo or stepper?

If it is a stepper, make sure that your Stepper steps per revolution and Encoder steps per revolution are set correctly in the Measurement & Automation Explorer.
If it is a servo, the motor may not be properly tuned.  Follow the steps in the tutorial below to manually tune your motor:
Understanding Servo Tune

See the KnowledgeBase article below to help troubleshoot the following errors:
KB 3QGEF7D3: Following Error in a Motion Control System

What exactly is happenning when you say "The parallel motors seem to build up tension even though they report being at the same position"?

Allen H.

[jspaarg]

allen_h: What exactly is happenning when you say "The parallel motors seem to build up tension even though they report being at the same position"?

The two X axes are physically 48" apart.  We decided to have two independent motors (instead of a dead rail). 

They are connected by a crossbar (the Y axis) which weighs about 110 pounds.  The axis itself weighs about 80 pounds and the Z axis (which moves on the crossbar) weighs about 30 pounds.  The Z axis is typically closer to X' than X.  Home for the Y axis is on the X' side.

I turn off the X' axis and let it "relax" to a non-tension state and then set the stage position to match the X axis.

e.g. both motors say that they are at 5.000 inches (or the approprate counts).  When I keep X enabled and kill X', X' moves to 4.997 inches.

I then tell X' that it is at 5.000 inches.  I believe that this removes any mechanical tension.

If I then move the motor to position 50.000 inches (both axes show 50.000 inches) and perform the same "relax" technique, X' might move anywhere from 0.001 inches to 0.006 inches.  It seems that if both motors are indicating the same position and that they were "relaxed" prior to the move they should stay "relaxed" (no tension) at the end.

I admit to being new to this motor stuff, but what am I missing?

[allen_h]

It sounds like the National Instruments equipment and software is working if the motors are moving to your desired position when the motors are enabled.

I am not sure why the motors move when you kill the axis.  It could be the physics of the system (gravity, angle, etc) or it could be that killing the axis will also kill the torque that holds the axis in the specified position.  Killing the axis cuts off all power going to the motor from the motion controller allowing the motor to move freely.

Allen H.