On Sep 27, 2011, at 6:51 PM, Sebastian Kuzminsky wrote:
> On 09/21/2011 09:46 AM, Tom Easterday wrote:
>> I am using 2.4.6 with Grantrykins config to drive a gantry machine with 2 
>> motors on the Y axis.  I have tuned the machine and it seems to run fine, 
>> almost...  Using MDI, I can command any position at speed up to about 
>> 3300ipm.  Or, I can run ngc programs to exercise the gantry all day long.  
>> However….
>> 
>> 1) If I go into Axis' Manual Control tab (in World Mode), and try to jog via 
>> keyboard keys I can only do that if Jog Speed is<588 for X/Z axis, and<488 
>> for Y axis.  Anything above those speeds and I get an immediate following 
>> error and fault.   If I go into Joint Mode (while staying in Manual Control 
>> tab) I can jog X/Z at any speed.  I can also jog Y (probably at any speed), 
>> but in joint mode it would rack badly.
> 
> This paragraph raises two issues:
> 
> 1a) Jogging in Axis' Manual Control tab in World mode (aka Teleop mode) only 
> works at lower speeds.

Correct.

> 
> 1b) Jogging in Axis' Manual Control tab in Joint mode (aka Free mode) works 
> for X & Z at any speed, but racks the gantry.

I am saying that in joint mode it would rack only because I have two motors on 
the Y axis and joint mode only moves one at a time.

> I haven't looked at 1a yet, but it sounds like maybe it's something to do 
> with accel or vel limits of the joints themselves, vs the limits of the 
> trajectory planner?  I'm not really sure.
> 

Are there different accel and velocity settings for a joint?  I have them set 
in the ini file in the Display section and for each Axis (see configs linked 
below).  Am I missing something somewhere else?

.hal -> http://pastebin.com/MPyDjxNQ
.ini -> http://pastebin.com/kfshuc8C
kinematics.hal -> http://pastebin.com/gCkMtAVZ


> I do know what's wrong with 1b:
> 
> Joint-mode jogging of gantry machines doesn't work at all.  In joint mode 
> (aka Free mode), each joint is individually controlled, without any 
> coordination with other joints.  Thus the two joints that make up the 
> gantry's axis of motion will jog independently, and the gantry will rack.

Right, I understand that.  What I was trying to point out was that in Joint 
Mode in Manual Control tab I can move at any speed.  So why can't I do the same 
in World Mode (and Manual Control Tab)?

> 
> Gantry machines need to be homed in joint mode, same as all machines.  And 
> the gantry joints better have the same [AXIS_n]HOME_SEQUENCE!  But then they 
> must be jogged in world mode (aka Teleop mode) only.  Don't jog gantries in 
> joint mode or you'll rack!

That raises a question about homing.  If I have to home in joint mode does that 
mean I have to use world mode to get really close, and then use joint mode to 
move each Y motor until it is homed?

-Tom

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