Motion Control and Motor Drives

cancel
Showing results for 
Search instead for 
Did you mean: 

Settings for stepper motor

Hi all,

          I am trying to control a 1.8 deg step motor of Pacific scientific(N33HRHJ) using Labview 8.2 . I am using it to pull a incremental load ( upto 400 lb)  in velocity control mode - however beyond a certain load the motion of the motor is becoming jerky. I have been using microsteppings of 50,000 for making my moves.

 

Is there a way to overcome this using the MAX settings - specially the trajectory / control loop settings ?

 

With regards.

 

Partha

0 Kudos
Message 1 of 14
(4,257 Views)
What is the motor connected to?  A ballscrew actuator?  Jerky motion is not a characterstic of stepper motors.  They either step at the given rate or they stall.  You will get more torque if you don't microstep.  You may be able to change how the motor phases are connected (parallel or serial) to change the torque curve.  What RPM is your motor running at?
0 Kudos
Message 2 of 14
(4,255 Views)

Hi Brian,

               The motor is connected to a ball screw actuator through a double helical bearing joint. The maximum rot'n speed I am using is 1 rpm. I can clearly feel that the motor is stopping for split seconds, and then again starts working at higher loads.

 

The drive I am using is Pacifc scientific P70530.

 

Regards,

 

Partha  

0 Kudos
Message 3 of 14
(4,237 Views)
What is the lead of your ballscrew?  It sure sounds like you need a lower lead ballscrew, a gearbox, or a bigger motor. 
0 Kudos
Message 4 of 14
(4,233 Views)
The pitch is 0.98 inch and diameter of the screw is 0.98 in too.
0 Kudos
Message 5 of 14
(4,231 Views)
Both of those are oddball sizes.  1" x 1" would be more typical.  Either way, that is considered a high-lead ballscrew, and is usually used for high (linear) speed applications.
Message Edited by Brian Beal on 03-14-2009 11:55 AM
0 Kudos
Message 6 of 14
(4,228 Views)

So what will be the effect on the consistency of motor velocity considering the speed at which I am running?

 

Partha

0 Kudos
Message 7 of 14
(4,224 Views)
Velocity will be unreliable.  You are overloading the motor.  It won't hurt it, but you won't know where you are at.
0 Kudos
Message 8 of 14
(4,220 Views)
Is there a way to calculate the max rotation speed at which I can run without sacrificing the accuracy of velocity
0 Kudos
Message 9 of 14
(4,214 Views)
Torque Required=(Load*Lead)/(2*pi*e).  Load is in pounds, lead is in inches, e is efficiency.  e=0.85 for a ballscrew, 0.35 for an acme screw.  Result is inch-pounds.  For your load of 400 pounds, that is about 1200 in-oz.  You can get that amount of torque from a 2 or 3 stack high torque NEMA 34 stepper, but not a NEMA 23.
0 Kudos
Message 10 of 14
(4,209 Views)