Servo Motor Problem

aravindsingh

Hi,

I am using Basic Stamp 2 and programming it to move forward. I have connected the servo motor to pin 12 and 13 the command that i am using is very basic that is

do
pulsout 12, 650
pulsout 13, 850
pause 20
loop
end


when i am running the Boebot it is not moving straight but taking aa slight curvature path. i am not able to understand the problem

1. i have changed the servo motor still same problem i their
2. I have changed the basic stamp still the same problem is their
3. i have re installed the IDE still same problem is their
4. I have done the experiment with fresh batteries

the voltage level at pin 12 and 13 are same when the servo motors are moving in the same direction.


Please help i am stuck

with regards

Aravind Singh

dev/null

This might be caused by mechanical differences on the wheels. You should try adjusting the pulse width.
For instance PULSOUT 12, 670 or PULSOUT 12, 630

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Don't worry. Be happy

aravindsingh

thanks for replying.......

i have tried doing that but still it is not working . i see that the chasis of the boe bot is little distorted. Let me correct it if still problem persists then please help

with regards
Aravind Kumar Singh

$WMc%

Aravind

Servos are mechanical devices, No two servos are the same.

Write a correction subroutine to correct the defiant servo.


_______________$WMc%______Just think about it___

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The Truth is out there············································ BoogerWoods, FL. USA

aravindsingh

i have fixed the chasiss. still is not working i.e, moving forward. please help

dev/null

Since you have interchanged your servoes, it is not a servo problem. It's do to a mechanical unbalance in your robot. You should be able to compensate wth pulsewidths. Try different values between 650 and 850.
For example:
do
pulsout 12, 600
pulsout 13, 850
pause 20
loop
end

or

do
pulsout 12, 650
pulsout 13, 800
pause 20
loop
end

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Don't worry. Be happy

Daniel L.

Try setting P13 to 1000 and P12 to 500, It made it straight for me, don't ask me why.


I think it has to do with the pulsout making the servos going past their max speed. Since the servos are about the same, both going their max speed should make it straight.

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Daniel L.

AKA, The Ninja of Frozen Milk
AAKA, ゆきごくろさき (Yukigo Kurosaki )

Post Edited (Daniel L.) : 7/25/2009 4:37:11 PM GMT

aravindsingh

thanks for helping me

i have adjusted the speed of the servo motors and have come to an trade off between motion and the PWM value given to the motors.. i am able to get good straight motion 80 % perfect.

but i am not able to figure it why it is behaving so.

Thanks to all

Prettybird

Do both servos stop with the polsout 750? I am a newbee too but found out equal values not the same for both servos. Just alot of trial and error to make perfect. It describes in the Boe book

dw101s

Prettybird is on to the solution to the problem. If you do the following

do
pulsout 12, 750
pulsout 13, 750
loop

and if either of the servos are still moving you need to take a screw driver and adjust the servos' center mark to make the servo stop moving at pulsout 750. Its in the BOE book, its free from parallax.com

isofuncurves

I am testing the servo "sub-assemblies" right now. I experience the same situation. What I seem to notice is that which ever pin is listed first, that servo is traveling a little faster. For example, using this code:

DO
PULSOUT 12, 850
PULSOUT 13, 650
PAUSE 20
LOOP

I set the servos side by side with the control arms over-lapping and centered but not touching. when I run the program Servo 12 catches servo 13 and the servo arms start hitting. If I reverse the 12 and 13 in the above code, servo 13 catches servo 12.

The closest I can get them to matching speed is:
DO
PULSOUT 12, 809
PULSOUT 13, 650
PAUSE 20
LOOP

which seems like a big discrepancy. 750 does stop both servos. The offset doesn't appear to be the symetrical when switching directions.

Just some observations...