Smooth Sinusoidal Motion without Gearing, Onboard Buffer/Contouring?

[nstroud]

Hello,

My end goal is to have a stepper motor (200 steps/rotation) produce a smooth sinusoidal motion at 1Hz with an amplitude of 200-500 steps. Everything I've read so far has lead me to believe that this is impossible given the 7330 Motion Controller.

My best results were produced when an array of points were created, and used to change the Target Position inside a While Loop. The frequency was varied by changing number of points in the array that represent a complete cycle (an array of 32 data points results in a higher frequency than an array of 64 data points). However, this was not acceptable as the motion at 1Hz was not smooth. I've tried playing around with acceleration, deceleration, velocity, and S-curve Time, but to no avail.

I've thought about using the built in "Load Circular Arc" VI, and just assigning the 2nd motor axis as a dummy output, but this is not a good solution as I will eventually be using all 4 axis of the Motor Drive.

My question: Is it indeed impossible to produce a smooth sinusoidal motion of 1Hz with a 7330 Motion Controller? I realize "smooth" is objective, but the motion produced by the "Load Circular Arc" VI is "smooth" enough.

Equipment/Software:

PCI 7330 Motion controller

MID-7604 Motor Drive

LabView 2009

Any information towards this matter is greatly appreciated. Thank you,

Nick

[Jochen · Accepted solution]

Nick,

as it looks like you have already found all possible solutions for your task. In fact arc moves with a dummy axis would be the only reliable solution for your setup. If you can't afford to waste an axis, the only alternative solution is to switch to a 7344, which supports contouring.

Please note, that the 7330 is our low cost solution for basic motion control tasks with stepper motors. Advanced trajectories are not within the scope of this product, so if this is a requirement, please contact your local NI branch. Depending if you have just recently purchased the 7330 or not, they might be able to offer you a hardware upgrade to the 7340.

Kind regards,

Jochen Klier

National Instruments