Gantrykins Questions

PortlandGTS wrote:

At first, I was getting following errors. I found this thread which helped a lot:

www.linuxcnc.org/index.php/english/compo...=10&id=22514&limit=6

Have you tried different values for DEFAULT_ACCELLERATION?
It needs to be a little less than the STEPGEN_MAXACCEL

PortlandGTS wrote:

That sounds like the problem. I have max_acceleration higher than maxaccel.

That fits the behaviour seen, with an overshoot and backup.

Imagine that the motion planner is the rabbit on the side of a greyhound track. Further imagine that you are driving a sleigh drawn by reindeer, and job is to exactly follow the rabbit.
(you are the stepgen, by the way).
So, the rabbit sets off, and you crack the whip and set off in pursuit. The rabbit is a bit faster (being electric, after all) but you have a higher top speed, so eventually, after an initial lag, you catch up and pace the rabbit for a lap.
Then the rabbit stops. Your lack of acceleration is now more obvious, as no matter how loudly you shout "Whoah Prancer! Whoah! Dancer" the sleigh over shoots the rabbit, and you then have to come to a halt and persuade the reindeer to back up.

That's your machine, that is.

PortlandGTS wrote:

One last question: Since I switched to the 5i25, I frequently hear a little "chirp' from the motor when a joint stops moving. Is this anything to worry about?

It might be, is there any indication that the motor is slipping a few steps at that point? it may be that your DEFAULT_ACCELLRATION limit is still a little high.

PortlandGTS wrote:

One last question: Since I switched to the 5i25, I frequently hear a little "chirp' from the motor when a joint stops moving. Is this anything to worry about?

Tom,

Run the stepper test from the manual to check for missing steps at direction change.

John

If you missed any steps at all something is wrong. The chirp at direction change may be you need to increase the direction change times.

John