Boe rev b problems
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Posts: 46,084
Hi,
I just got my BOE rev B and here is my problem: when i plug the two
servo motors of my BOEBOT in the special plugs of the board, the
robot spins around instead of going ahead.
Why? This didn't occured with my other BOE.
Thanks a lot.
I just got my BOE rev B and here is my problem: when i plug the two
servo motors of my BOEBOT in the special plugs of the board, the
robot spins around instead of going ahead.
Why? This didn't occured with my other BOE.
Thanks a lot.
Comments
thekoookooo@y... writes:
> I just got my BOE rev B and here is my problem: when i plug the two
> servo motors of my BOEBOT in the special plugs of the board, the
> robot spins around instead of going ahead.
> Why? This didn't occured with my other BOE.
>
Remember that one servo goes from 750 to 1500 and the other servo goes from
750 to 0. That will give you straight ahead or straight back. The servos
actually rotate in the same direction but one servo is mounted 180 degrees
from the other.
Sid
[noparse][[/noparse]Non-text portions of this message have been removed]
easier than remembering one is backwards.
Original Message
> > I just got my BOE rev B and here is my problem: when i plug the two
> > servo motors of my BOEBOT in the special plugs of the board, the
> > robot spins around instead of going ahead.
> > Why? This didn't occured with my other BOE.
> >
>
> Remember that one servo goes from 750 to 1500 and the other servo goes
from
> 750 to 0. That will give you straight ahead or straight back. The servos
> actually rotate in the same direction but one servo is mounted 180 degrees
> from the other.
All i'm saying is that the commands
pulsout 3,715
pause 20
pulsout 15,715
pause 20
on my first BOE, turned the both motors in the right direction, and
the robot advanced. On my second BOE, the robot spins when I use
those commands.
--- In basicstamps@y..., Newzed@a... wrote:
> In a message dated 08/23/2002 15:05:13 Eastern Daylight Time,
> thekoookooo@y... writes:
>
>
> > I just got my BOE rev B and here is my problem: when i plug the
two
> > servo motors of my BOEBOT in the special plugs of the board, the
> > robot spins around instead of going ahead.
> > Why? This didn't occured with my other BOE.
> >
>
> Remember that one servo goes from 750 to 1500 and the other servo
goes from
> 750 to 0. That will give you straight ahead or straight back. The
servos
> actually rotate in the same direction but one servo is mounted 180
degrees
> from the other.
>
> Sid
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
It could also be that the neutral value for the servos is so far off that
one runs forwards and one runs backwards.
If you take two identical servos and do the continuous rotation hack, mount
them back to back on a robot, then issue the same pulsout values to both of
them, the robot will spin. Both servos are turning the same direction, but
one is physically backwards from the other.
Original Message
> All i'm saying is that the commands
>
> pulsout 3,715
> pause 20
> pulsout 15,715
> pause 20
>
>
> on my first BOE, turned the both motors in the right direction, and
> the robot advanced. On my second BOE, the robot spins when I use
> those commands.
> > > I just got my BOE rev B and here is my problem: when i plug the
> two
> > > servo motors of my BOEBOT in the special plugs of the board, the
> > > robot spins around instead of going ahead.
> > > Why? This didn't occured with my other BOE.
> > >
> >
> > Remember that one servo goes from 750 to 1500 and the other servo
> goes from
> > 750 to 0. That will give you straight ahead or straight back. The
> servos
> > actually rotate in the same direction but one servo is mounted 180
> degrees
> > from the other.
> >
> > Sid
> >
> >
> > [noparse][[/noparse]Non-text portions of this message have been removed]
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
Actually the old servos were from Parallax, the new ones are HITEC
servos modified by miself for continuos rotation. I just replaced the
pot with 2 2K resistors in series. Maybe I did't wired them
properly...
--- In basicstamps@y..., Rodent <daweasel@s...> wrote:
> Sounds to me like the old servos had a motor hack and the new ones
did not.
> It could also be that the neutral value for the servos is so far
off that
> one runs forwards and one runs backwards.
>
> If you take two identical servos and do the continuous rotation
hack, mount
> them back to back on a robot, then issue the same pulsout values to
both of
> them, the robot will spin. Both servos are turning the same
direction, but
> one is physically backwards from the other.
>
>
Original Message
>
> > All i'm saying is that the commands
> >
> > pulsout 3,715
> > pause 20
> > pulsout 15,715
> > pause 20
> >
> >
> > on my first BOE, turned the both motors in the right direction,
and
> > the robot advanced. On my second BOE, the robot spins when I use
> > those commands.
>
> > > > I just got my BOE rev B and here is my problem: when i plug
the
> > two
> > > > servo motors of my BOEBOT in the special plugs of the board,
the
> > > > robot spins around instead of going ahead.
> > > > Why? This didn't occured with my other BOE.
> > > >
> > >
> > > Remember that one servo goes from 750 to 1500 and the other
servo
> > goes from
> > > 750 to 0. That will give you straight ahead or straight back.
The
> > servos
> > > actually rotate in the same direction but one servo is mounted
180
> > degrees
> > > from the other.
> > >
> > > Sid
> > >
> > >
> > > [noparse][[/noparse]Non-text portions of this message have been removed]
> >
> >
> > To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@y...
> > from the same email address that you subscribed. Text in the
Subject and
> Body of the message will be ignored.
> >
> >
> > Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
> >
> >
I never remove the pot and install resistors -- I always leave the pot
intact so I can pop the top, take the one gear off and tweak the pot so both
servos have matching values for the stopped position.
Original Message
> Actually the old servos were from Parallax, the new ones are HITEC
> servos modified by miself for continuos rotation. I just replaced the
> pot with 2 2K resistors in series. Maybe I did't wired them
> properly...
http://www.acroname.com/robotics/info/ideas/continuous/continuous.html
but I realise now that I made a mistake: I've used 2K resistors
instead of 2.4K. Maybe that's the problem...
one
on that first BOE bot. Maybe when the early ones were shipping they did it
for you way back then.
If one servo is reversed, then the same command would work for both causing
the bot to move forward and not spin in a circle.
Original Message
From: thekoookooo [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=iZqty8cR0DvqirzTREvoXh0yQmApGRV_BKvTUQaXKH4O4_NtPwFkvWIK_gE6tA6E9EbTCWb8yX9rGaIPQOuH]thekoookooo@y...[/url
Sent: Friday, August 23, 2002 7:31 PM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Re: BOE REV B PROBLEMS
Hi,
All i'm saying is that the commands
pulsout 3,715
pause 20
pulsout 15,715
pause 20
on my first BOE, turned the both motors in the right direction, and
the robot advanced. On my second BOE, the robot spins when I use
those commands.
--- In basicstamps@y..., Newzed@a... wrote:
> In a message dated 08/23/2002 15:05:13 Eastern Daylight Time,
> thekoookooo@y... writes:
>
>
> > I just got my BOE rev B and here is my problem: when i plug the
two
> > servo motors of my BOEBOT in the special plugs of the board, the
> > robot spins around instead of going ahead.
> > Why? This didn't occured with my other BOE.
> >
>
> Remember that one servo goes from 750 to 1500 and the other servo
goes from
> 750 to 0. That will give you straight ahead or straight back. The
servos
> actually rotate in the same direction but one servo is mounted 180
degrees
> from the other.
>
> Sid
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
To UNSUBSCRIBE, just send mail to:
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for you by Parallax.
Original Message
From: thekoookooo [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=nHV7Ywol2RQI6VO8Fc47OUo2r3b_2LMD0DMMnQlSb6IoHcWTVg1Y-cIskq-AN3us5yQwmTyW8VdVrC-ZGio]thekoookooo@y...[/url
Sent: Friday, August 23, 2002 8:05 PM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Re: BOE REV B PROBLEMS
Well,
Actually the old servos were from Parallax, the new ones are HITEC
servos modified by miself for continuos rotation. I just replaced the
pot with 2 2K resistors in series. Maybe I did't wired them
properly...
--- In basicstamps@y..., Rodent <daweasel@s...> wrote:
> Sounds to me like the old servos had a motor hack and the new ones
did not.
> It could also be that the neutral value for the servos is so far
off that
> one runs forwards and one runs backwards.
>
> If you take two identical servos and do the continuous rotation
hack, mount
> them back to back on a robot, then issue the same pulsout values to
both of
> them, the robot will spin. Both servos are turning the same
direction, but
> one is physically backwards from the other.
>
>
Original Message
>
> > All i'm saying is that the commands
> >
> > pulsout 3,715
> > pause 20
> > pulsout 15,715
> > pause 20
> >
> >
> > on my first BOE, turned the both motors in the right direction,
and
> > the robot advanced. On my second BOE, the robot spins when I use
> > those commands.
>
> > > > I just got my BOE rev B and here is my problem: when i plug
the
> > two
> > > > servo motors of my BOEBOT in the special plugs of the board,
the
> > > > robot spins around instead of going ahead.
> > > > Why? This didn't occured with my other BOE.
> > > >
> > >
> > > Remember that one servo goes from 750 to 1500 and the other
servo
> > goes from
> > > 750 to 0. That will give you straight ahead or straight back.
The
> > servos
> > > actually rotate in the same direction but one servo is mounted
180
> > degrees
> > > from the other.
> > >
> > > Sid
> > >
> > >
> > > [noparse][[/noparse]Non-text portions of this message have been removed]
> >
> >
> > To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@y...
> > from the same email address that you subscribed. Text in the
Subject and
> Body of the message will be ignored.
> >
> >
> > Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
> >
> >
To UNSUBSCRIBE, just send mail to:
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I always wind up using the pot in the servo or hooking up a small external
one to make centering the servo easier. What I'd do is measure the
resistance of the pot itself, and try to match up two resistors to match
that closely. Some servos aren't using 5k pots, but some other value.
Some servos are nice in that you can take a small jeweler's screwdriver and
reach down through the output gear shaft to the pot (it has a slotted shaft
end for this) and tweak it a bit for centering (you turn it a bit one way or
the other slightly). Unfortunately, most of the inexpensive servos nowadays
don't have that feature anymore. Of course in the newer RC radio equipment
they have all sorts of features built in to the transmitter negating the
need for it anymore too.
If you want to reverse a servo, it is quite simple, reverse the two outside
wires on the pot (leave the wiper or center wire alone), then reverse the
two wires on the motor. Then recenter the servo (it'll be off until you
recenter it) and your in business.
Original Message
From: thekoookooo [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=dCbu1feict_8MGe901YYVuE7VISNsecGPqFH6Q796Kscoa0Zzh11sPViU9FdECfu6zY3nybY1xI56T3MyA]thekoookooo@y...[/url
Sent: Friday, August 23, 2002 9:35 PM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Re: BOE REV B PROBLEMS
Actually I modified the servos as described in this article:
http://www.acroname.com/robotics/info/ideas/continuous/continuous.html
but I realise now that I made a mistake: I've used 2K resistors
instead of 2.4K. Maybe that's the problem...
To UNSUBSCRIBE, just send mail to:
basicstamps-unsubscribe@yahoogroups.com
from the same email address that you subscribed. Text in the Subject and
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radios have reversing now, so you don't see them anymore. There is
no standard as to which way is forward/reverse so it may be
different between brands.
> I think somehow you got one servo that is reversed versus the normal
> forward one on that first BOE bot. Maybe when the early ones were shipping
> they did it for you way back then. If one servo is reversed, then the same
> command would work for both causing the bot to move forward and not spin
> in a circle.