MAM speed and accel units RSLogix 5000

[robertmee]

drbitboy's calcs are correct. He is assuming that ramping up is 30 ms and 30 ms is ramping down so each ramp is 15 inches long. I get different ( lower ) accel number because I am assuming the ramp up is 30 ms and the ramp down is 30 ms. Even so the acceleration and deceleration rates are TOO DAMN HIGH.


The problem is the 60 ms. Not possible. Even if I break the motion profile into separate accel, constv, and decel segments the constv=750 in/s and the accel and decel rates are 37500 in/s^2



Then there is this thing call the frequency of acceleration or motion. Assuming ramping up and ramp down take all the time then the frequency of motion is 1/60ms = 2.6 Hz. The open loop frequency needs to be about 4 times that. Robertmee said his system is massive so I doubt his system is fast enough. Another way of looking at it that if it takes 5 time constants to get within 1% of the final velocity, time constant of the system must be about 1/5th of the time it takes to get to peak velocity.
I doubt the motor and load have a time constant of about 12, better yet 10 ms.


Robertmee needs to show a trend and 1 ms intervals showing the target trajectory or we are guessing except being able to calculate it won't work.

It works fine....each motion is 40ms in duration, 1ms sampling on a trend. Motion event is on a 2ms motion event task (coarse update rate of motion group), task itself is 680 us. Ran it for about 4 hours today, motor never exceeded 78 degrees F. The cycle is 4 moves in apx 3 sec, repeat over and over, each complete move is 150ms in duration (40ms up, 40ms down, 70ms dwell at position between moves). Peak torque around 90%. L72s processor running around 60% utilization on the processor.

I should have took a screen shot of the trends, but was busy screenshotting HMI screens to pit together some info for engineering. I won't be back on site until Dec 8th, but can take screen shots then. The adaptive tuning of the axis put max accel at six figure acceleration, and velocity around 8000. I'm at 2500 and 60,000, so well within reason. There Is a sister system that's been running on Yaskawa MP940s with Sigma II amplifiers, that runs at 3000 and 72000 respectively. Apx same size motors. Been running since 2007. The motors are large but the load is minimum. Basically just contending with motor inertia, not some heavy load.