Bipod setup

dab77
Offline
Elite Member

11 Aug 2010 11:42 - 11 Aug 2010 11:43 #3692 by dab77

Replied by dab77 on topic Re:Bipod setup

The img i attached is a screenshot with halscope triggering axis.0.ferror.
channels motor-pos-cmd and motor-pos-fb have the same scale, so i think is the result of what you suggested.

what do you think?

...and thanks for your time and interest..

Last edit: 11 Aug 2010 11:43 by dab77.

Please Log in or Create an account to join the conversation.

andypugh
Offline
Moderator

11 Aug 2010 11:56 #3693 by andypugh

Replied by andypugh on topic Re:Bipod setup

It is a bit difficult to see what is happening there because the scales are so big for the cmd and fb channels.
You can apply an offset to the -cmd and -fb channels (the button at the bottom of the scale slider) which will then let you decrease the scale while keeping the traces on the screen.

However, I think I can see a change in the -cmd value, but not in the -fb value..

Please Log in or Create an account to join the conversation.

dab77
Offline
Elite Member

11 Aug 2010 12:21 #3696 by dab77

Replied by dab77 on topic Re:Bipod setup

better?

Please Log in or Create an account to join the conversation.

andypugh
Offline
Moderator

11 Aug 2010 13:29 #3698 by andypugh

Replied by andypugh on topic Re:Bipod setup

At a guess, I would say that STEPGEN_MAXACCEL is much lower then MAX_ACCEL in the INI file. Basically the stepgen is not keeping up with the command.
This is nothing to do with the kinematics module. (but to test that you should perhaps re-test with the original, unmodified trivkins kinematics module, if you still have it)

Another possibility is that the combination of base-period length, step-per rev and axis-scale is much lower than the max velocity of the axes.

Please Log in or Create an account to join the conversation.

dab77
Offline
Elite Member

11 Aug 2010 13:31 #3699 by dab77

Replied by dab77 on topic Re:Bipod setup

ok..
kind of my newbie fault. :blush:

with a very low speed it works!
before i left for each motor a good speed, which was 600mm/s.
i had to set it to 50mm/s to make it work without errors...
now i have a big noise coming from my motors (nema23-3A...chinese...)with low speed, but i'm going to play a bit with microstepping. now working with 1/2.

thanks again!
if you have any other suggestions, you're welcome!

cheers, dab.

Please Log in or Create an account to join the conversation.

andypugh
Offline
Moderator

11 Aug 2010 13:46 #3701 by andypugh

Replied by andypugh on topic Re:Bipod setup

Post your INI file, I think I know what the problem might be.

Please Log in or Create an account to join the conversation.

dab77
Offline
Elite Member

12 Aug 2010 13:18 #3719 by dab77

Replied by dab77 on topic Re:Bipod setup

wow!!
that's my .ini:

[EMC]
MACHINE = Prova_Bipod
DEBUG = 0x7FFFFFFF

[DISPLAY]
DISPLAY = axis
EDITOR = gedit
POSITION_OFFSET = RELATIVE
POSITION_FEEDBACK = ACTUAL
MAX_FEED_OVERRIDE = 1.2
INTRO_GRAPHIC = emc2.gif
INTRO_TIME = 2
PROGRAM_PREFIX = /home/dab-cnc/emc2/nc_files/bipod
INCREMENTS = 50mm 10mm 5mm 1mm .5mm .1mm .05mm

[FILTER]
PROGRAM_EXTENSION = .png,.gif,.jpg Greyscale Depth Image
PROGRAM_EXTENSION = .py Python Script
png = image-to-gcode
gif = image-to-gcode
jpg = image-to-gcode
py = python

[TASK]
TASK = milltask
CYCLE_TIME = 0.010

[RS274NGC]
PARAMETER_FILE = emc.var

[EMCMOT]
EMCMOT = motmod
COMM_TIMEOUT = 1.0
COMM_WAIT = 0.010
BASE_PERIOD = 100000
SERVO_PERIOD = 1000000

[HAL]
HALFILE = Prova_Bipod.hal
HALFILE = custom.hal
POSTGUI_HALFILE = custom_postgui.hal

[TRAJ]
AXES = 3
COORDINATES = X Y Z
LINEAR_UNITS = mm
ANGULAR_UNITS = degree
CYCLE_TIME = 0.010
DEFAULT_VELOCITY = 50.00
MAX_LINEAR_VELOCITY = 1800.00

[EMCIO]
EMCIO = io
CYCLE_TIME = 0.100
TOOL_TABLE = tool.tbl

[AXIS_0]
TYPE = LINEAR
HOME = 0.0
MAX_VELOCITY = 1800.0
MAX_ACCELERATION = 3000.0
STEPGEN_MAXACCEL = 3750.0
SCALE = 5.19953204212
FERROR = 1.0
MIN_FERROR = 1.0
MIN_LIMIT = -2000.0
MAX_LIMIT = 2000.0
HOME_OFFSET = 0.0

[AXIS_1]
TYPE = LINEAR
HOME = 0.0
MAX_VELOCITY = 1800.0
MAX_ACCELERATION = 3000.0
STEPGEN_MAXACCEL = 3750.0
SCALE = 5.19953204212
FERROR = 1.0
MIN_FERROR = 1.0
MIN_LIMIT = -2000.0
MAX_LIMIT = 2000.0
HOME_OFFSET = 0.0

[AXIS_2]
TYPE = LINEAR
HOME = 0.0
MAX_VELOCITY = 1800.0
MAX_ACCELERATION = 3000.0
STEPGEN_MAXACCEL = 3750.0
SCALE = 5.19953204212
FERROR = 1.0
MIN_FERROR = 1.0
MIN_LIMIT = -2000.0
MAX_LIMIT = 2000.0
HOME_OFFSET = 0.0

50 mm/s is the max vel i can jog in world mode... ...but, if i run the example text path, the 'not-cutting-movements' are done correctly at max vel what i think is 1800mm/s. am i right?

Please Log in or Create an account to join the conversation.

andypugh
Offline
Moderator

12 Aug 2010 14:20 #3720 by andypugh

Replied by andypugh on topic Re:Bipod setup

dab77 wrote:

BASE_PERIOD = 100000
SERVO_PERIOD = 1000000

[AXIS_0]
MAX_VELOCITY = 1800.0
MAX_ACCELERATION = 3000.0
STEPGEN_MAXACCEL = 3750.0
SCALE = 5.19953204212
FERROR = 1.0
MIN_FERROR = 1.0

You do have a rather slow base thread.

Looking at the numbers:
A max velocity of 1800mm/sec and a scale of 5.2 means a max pulse rate of 9360Hz
A Base period of 100,000 nS means that the stepgen runs at a max of 10kHz (assuming that Reset is active, which I think it is, otherwise it is 5kHz)

So, it is not exactly what I thought the problem was, but bear in mind that any increase in your microstep level will halve your top speed. Also not that at the moment at high speed the stepgen has a choice of 1800mm/sec, 900mm/sec, 600mm/sec, 450mm/sec etc. These big jumps are likely to lead to motor stalling problems.

Is your latency really so bad that you need a 100000nS base period? Generally anything worse than 50000 means that the computer is not really suitable for RT work (and <20000 is desirable)

Assuming a 200 step motor and half microstepping, you seem to be asking the motors to run at 1500rpm at the top end, this is rather fast for a stepper, especially when you are asking it to jump from 750 to 1500 rpm instantaneously due to the limited step resolution.

As an experiment, though, try increasing the accellerations by a factor of 5 and see what happens.

Please Log in or Create an account to join the conversation.

dab77
Offline
Elite Member

12 Aug 2010 19:30 #3722 by dab77

Replied by dab77 on topic Re:Bipod setup

you're right..
don't know how stepconf wizard translated the 15000ns max base jitter, with that 100000 ns base period..
now this is my new .ini file:
...cutted...

[EMCMOT]
EMCMOT = motmod
COMM_TIMEOUT = 1.0
COMM_WAIT = 0.010
BASE_PERIOD = 18000
SERVO_PERIOD = 100000
...
[TRAJ]
AXES = 3
COORDINATES = X Y Z
LINEAR_UNITS = mm
ANGULAR_UNITS = degree
CYCLE_TIME = 0.010
DEFAULT_VELOCITY = 100.00
MAX_LINEAR_VELOCITY = 1000.00

[EMCIO]
EMCIO = io
CYCLE_TIME = 0.100
TOOL_TABLE = tool.tbl

[AXIS_0]
TYPE = LINEAR
HOME = 1000.0
MAX_VELOCITY = 950.024698419
MAX_ACCELERATION = 6000.0
STEPGEN_MAXACCEL = 7500.0
SCALE = 41.5962563369
FERROR = 1.0
MIN_FERROR = .25
MIN_LIMIT = -3000.0
MAX_LIMIT = 3000.0
HOME_OFFSET = 1000.0

i have less problems, this way, but still i'm not happy.
do you know why in joint mode i can reach without problems very high speed, while in world mode i can jog at a max speed of someting like 4000 mm/min? it's very low speed... in joint mode 1500-2000 mm/s are possible, the only limit are my fingers and eyes!!!

by the way my EMC-PC is a notebook with P4 - 3GHz processor, 1G of RAM... I think it has to run!

Please Log in or Create an account to join the conversation.

dab77
Offline
Elite Member

12 Aug 2010 19:41 #3723 by dab77

Replied by dab77 on topic Re:Bipod setup

taking the min ferror from .25 to 3 made the things lot better!!!
now i can jog in world mode at 11000 mm/min of speed..

Please Log in or Create an account to join the conversation.

Time to create page: 0.305 seconds

Bipod setup

Attachments:

Attachments: