Motion profile generator.

[richard]

I understand what your saying , but the array data is only required for the acceleration phases of each move the constant velocity part if one is required can easily just be a loop terminating when actual_position is less than or equal to target-ramp_length. so moves of any length are possible. I envision the deceleration would need error correction applied as
error = (actual_position - (target-(ramp_length-array[])) , each iteration would be adjusted by that error and the ramp_length decremented by the array [] increment . with potentially 60 odd iterations the final movement should be pretty good. (ramp_length=0 and error=0)=good
I agree about the jerkiness I'm hoping inertia will smooth some out , tell me if you feed a 200 step increment into the pid how many iterations till the error is 0 ? . my guess is that its more the 1 ,this may also do a bit of smoothing.

[HenrikOlsson]

Hi Richard,

tell me if you feed a 200 step increment into the pid how many iterations till the error is 0 ? my guess is that its more the 1 ,this may also do a bit of smoothing.

Yes, of course it's more than one, perhaps 20-200.
Exactly HOW many depends on the inertia of the system, the tuning of the PID parameter, encoder resolution, current limit of the drive etc etc etc. Aggressive tuning will cause overshoot and ringing, "loose" tuning will cause slow risetime and so on - as I'm sure you know.

I think that what you're aiming to do with recalcuating the array is basically what I'm doing as well - except I do it on the fly at each tick. What your method have going for it, provided it works of course, is that you don't use a division in the recalculation phase which will make it run fast. Then, on the other hand, if you need to recalcute the what's left of the array each tick (not sure if you need that or not?) then it might not be more effecient, I don't know.

Please do keep posted and I'll do the same - if I could just find the time to sit down and actually get it running...

Thanks Richard!
/Henrik.