Submitted by eyedesign on Tue, 11/02/2010 - 13:17
Posted in
Hello all,
After taking almost a month to get my dolly up and running took it out this weekend to run some tests. What I found is that the motor seems to have very little torque. If I try running the rig using the openmoco slim program shoot, move shoot. The only way I could get it to move a payload of about 1900g was to [4] > set_motor 1 steps 5. Anything over that speed will causes the motor to stall. I can pull the payload with code that is base on Intervalometer non-blocking timing code.
Using the non-blocking code what I get is continuous motion. This setup is workable but doesn't offer much control other then being able to set number of step and stepper speed using the arduino Stepper Library.
Question can I get more torque from this motor by changing something in the software or hardware?
I using this stepper motor with the EasyDriver V4.2. I'm running the motor on a 12v 41Ah power supply and the drive train is a timing belt and pulley in a omni configuration. The width of the pulley is 3cm.
Have you tried extending the
Have you tried extending the min step and max step parameters in slim? It may be that you have enough torque, but just can't handle the velocity (which is what it sounds like). Try making min step and max step about 2-3 times larger (see 'help stepper').
!chris
This is what I get when I
This is what I get when I change settings, just lockups up the program. I tried this a few way, place the command at the began after port and connect, after setting up the motor, placing the command at the end of the setup and before starting. Always the same program is locks and no way to stop it. I can stop the program by killing slim and reload the openmoco software.
Microsoft Windows XP [Version 5.1.2600]
(C) Copyright 1985-2001 Microsoft Corp.
C:\Dokumente und Einstellungen\Thomas>CD C:\OPENMOCO\openmoco-slim-0.12\openmoco
-slim-0.12
C:\OPENMOCO\openmoco-slim-0.12\openmoco-slim-0.12>
C:\OPENMOCO\openmoco-slim-0.12\openmoco-slim-0.12>openmoco-slim.pl
OpenMoco Slim Interface Version 0.12
(c) 2009, 2010 C. A. Church
This program is free software distributed under the terms of the GNU GPL v3
Type 'help' for help
[1] > port COM7
[2] > connect
[3] > set_motor 1 dir
[4] > set_motor 1 steps 10
[5] > set_motor 1 enable
[6] > set_camera exposure 500
[7] > set_camera cycle 2
[8] > set_camera shots 500
[9] > set_camera on
[10] > start
[11] > stop
[12] > stepper min_stp 500
[13] > stepper max_stp 500
[14] > start
[15] > stop
ERROR: Could Not Stop: [_openmoco_command] ERROR: Bizarre copy of UNKNOWN in aas
sign at C:/Perl/site/lib/Win32/SerialPort.pm line 1217, <> line 15.
ERROR: Could Not Stop: [_openmoco_command] ERROR: Bizarre copy of UNKNOWN in aas
sign at C:/Perl/site/lib/Win32/SerialPort.pm line 1217, <> line 15.
Can't coerce 4¬☺D¥├☺♦ ♣ ♥h¿├☺►À├☺ÿO$ \\.\COM7 ♦ ♦ ♥°ª├☺ º├☺ÿO$ use
start ♦ ▬☺♀♥h¯├☺ ÷├☺ÿO$
Can't coerce 4¬☺D¥├☺♦ ♣ ♥h¿├☺►À├☺ÿO$ \\.\COM7 ♦ ♦ ♥°ª├☺ º├☺ÿO$ use
start ♦ ▬☺♀♥h¯├☺ ÷├☺ÿO$
exit
☻ ▼☺♀♥°0─☺xJ─☺ÿO$ stop max_stp 500 0 xecution of the current program, or
resumes from
♀☺↕♥UNKNOWN to string in return at C:\OPENMOCO\openmoco-slim-0.12\openmoco-slim
-0.12\openmoco-slim.pl line 447, <> line 15.
Can't return outside a subroutine at C:\OPENMOCO\openmoco-slim-0.12\openmoco-sli
m-0.12\openmoco-slim.pl line 307, <> line 15.
I've tried setting min-max stp <250, 500, and 700> no movement on the motor with any of these setting. If I used the setting below it works but not great.
C:\OPENMOCO\openmoco-slim-0.12\openmoco-slim-0.12>openmoco-slim.pl
OpenMoco Slim Interface Version 0.12
(c) 2009, 2010 C. A. Church
This program is free software distributed under the terms of the GNU GPL v3
Type 'help' for help
[1] > port COM7
[2] > connect
[3] > set_motor 1 dir
[4] > set_motor 1 steps 10 5, 10, 20 steps that work
[5] > set_motor 1 ramp 0
[6] > set_motor enable
[7] > set_motor 1 enable
[8] > set_camera exposure 500
[9] > set_camera cycle 5
[10] > set_camera shots 999
[11] > set_camera on
[12] > start
The best being set_motor 1 steps 5. With all the other setting rig seems to make one step, miss one step, make a step.
It looks like you're running
It looks like you're running the async_motor branch of slim, rather than the production 0.12 version. This version isn't fully vetted yet, and may have issues. I suggest rolling back to the prod releases of Slim and the perl library, the errors indicate you're using the dev branch based on the line numbers reported.
I don't know what the cause of that issue is (and won't without being able to first re-create it, which looks tough based on the content of it from this vantage point), but I suggest going to the production releases of the arduino firmware, slim, and the perl timelapse library, and seeing if it occurs there. I know this feature was fully tested in the production version, and I've had no issue with it yet.
The problem with torque you're having sounds strongly like too much velocity, which the stepper command adjusts.
!chris
Also, you should try some
Also, you should try some variance (you need some velocity, setting min and max step rate the same equates zero velocity):
stepper min_stp 1000
stepper max_stp 3000
!c
This sounds a lot like the
This sounds a lot like the problem I had with torque.
We added the extra 1000 delay in the OM_Motor_Control code and it added the torque I was expecting to have. Remember?
I still think there is something odd going on here...
// wer're moving at maximum speed
delay = motor_min_step;
}
delayMicroseconds(1000); //added this extra delay to get more torque.
digitalWrite(motor_pin, LOW);
delayMicroseconds(delay);
Edit: I found the link to the thread about my motor torque problem. HERE
Thanks bdodds, Below are the
Thanks bdodds,
Below are the setting that I got to work.
Type 'help' for help
[1] > port COM7
[2] > connect
[3] > stepper min_stp 9000
[4] > stepper max_stp 11000
[5] > set_motor 1 dir 1
[6] > set_motor 1 steps 20
[7] > set_motor ramp 5
[8] > set_motor 1 ramp 5
[9] > set_motor 1 enable
[10] > set_camera exposure 500
[11] > set_camera cycle 5
[12] > set_camera shots 500
[13] > set_camera on
[14] > start
thomas