Hexapod servo stepping question

Archiver

Hello all:

I have created a hexapod from scratch and am now programming it to
walk. I am using a Basic stamp2 and 2 Scott Edwards SSC's for serial
leg control. I have succeded in programming the hexapod to perform
pushups and a rough walking cycle. My issue is that I would like to
slow the leg movements down, especially the "stride" part of the leg
walk cycle. I stripped my code down to just one leg to try to "step"
the servo's through a walk cycle, however only 1 servo of the leg
seems to step through properly. I put debug commands throughout the
code below to ensure correct values and that the "for/next" loops as
well as the "serout" commands have the correct values...all's well.
What is absolutely stumping me is the fact that the 1st servo
(servoposa(0)- the stride servo) steps slowly as the code dictates,
but the 2nd servo (the lift servo) does not (it quickly goes to a set
position without stepping), even though the codes debug command shows
it stepping through the entire range of values. I have looked and
tried all kinds of things with the code to solve it but to no avail.
I think another pair of eyes on the code below will spot the issue
(s)? FYI, I have swapped connectors on the leg end to ensure proper
functioning of the hardware....all ok. Any and all feedback would be
appreciated!

Here is the code:


'{$STAMP BS2}
x var nib
y var byte
serposa var byte(2)
serposb var byte(2)
stride var byte
liftl var byte

stride = 70
liftl = -20

serposb(0)= 150
serposb(1)= 90
'

---

serposa(0) = 150
serposa(1) = 130
gosub serout1

stand: ' stride and lift routine values

serposa(0) = serposb(0) + stride
' debug dec serposa(0)
serposa(1) = serposb(1) + liftl
' debug dec serposa(1)
gosub serout2
end

serout2: ' This will have the legs step through its values so they
move slowly

x=0
for x=0 to 1
' debug dec x
y=serposb(x)
' debug dec y
for y=serposb(x) to serposa(x)
serout 8,$4054,[noparse][[/noparse]255,x,y(x)]
'debug dec y
pause 20
next
pause 1000
next
pause 500
return


serout1:' this will put the legs in a "home position" before the walk
cycle

x=0
for x=0 to 1
serout 8,$4054,[noparse][[/noparse]255,x,serposa(x)]
next
pause 1000
return

Archiver

This doesn't help with your code problem, but I do know of a new
product coming out soon that may help. It is a 16 Serial Controller
from a company called Pololu (see www.pololu.com) They offer a more
robost version of Scott Edwards with control for speed. This way you
aren't burdening the stamp with trying to slow down the code
execution. The idea would be to send one command that tells the
servo not just where to go, but also how fast to move!

--- In basicstamps@y..., "kasaneus" <alex.dirks@w...> wrote:
>
> Hello all:
>
> I have created a hexapod from scratch and am now programming it
to
> walk. I am using a Basic stamp2 and 2 Scott Edwards SSC's for
serial
> leg control. I have succeded in programming the hexapod to perform
> pushups and a rough walking cycle. My issue is that I would like to
> slow the leg movements down, especially the "stride" part of the
leg
> walk cycle. I stripped my code down to just one leg to try
to "step"
> the servo's through a walk cycle, however only 1 servo of the leg
> seems to step through properly. I put debug commands throughout the
> code below to ensure correct values and that the "for/next" loops
as
> well as the "serout" commands have the correct values...all's well.
> What is absolutely stumping me is the fact that the 1st servo
> (servoposa(0)- the stride servo) steps slowly as the code dictates,
> but the 2nd servo (the lift servo) does not (it quickly goes to a
set
> position without stepping), even though the codes debug command
shows
> it stepping through the entire range of values. I have looked and
> tried all kinds of things with the code to solve it but to no
avail.
> I think another pair of eyes on the code below will spot the issue
> (s)? FYI, I have swapped connectors on the leg end to ensure proper
> functioning of the hardware....all ok. Any and all feedback would
be
> appreciated!
>
> Here is the code:
>
>
> '{$STAMP BS2}
> x var nib
> y var byte
> serposa var byte(2)
> serposb var byte(2)
> stride var byte
> liftl var byte
>
> stride = 70
> liftl = -20
>
> serposb(0)= 150
> serposb(1)= 90
> '

---

> serposa(0) = 150
> serposa(1) = 130
> gosub serout1
>
> stand: ' stride and lift routine values
>
> serposa(0) = serposb(0) + stride
> ' debug dec serposa(0)
> serposa(1) = serposb(1) + liftl
> ' debug dec serposa(1)
> gosub serout2
> end
>
> serout2: ' This will have the legs step through its values so they
> move slowly
>
> x=0
> for x=0 to 1
> ' debug dec x
> y=serposb(x)
> ' debug dec y
> for y=serposb(x) to serposa(x)
> serout 8,$4054,[noparse][[/noparse]255,x,y(x)]
> 'debug dec y
> pause 20
> next
> pause 1000
> next
> pause 500
> return
>
>
> serout1:' this will put the legs in a "home position" before the
walk
> cycle
>
> x=0
> for x=0 to 1
> serout 8,$4054,[noparse][[/noparse]255,x,serposa(x)]
> next
> pause 1000
> return

Archiver

I just created a hexapod from scratch and am now programming it too!! I
would love to see some photos of your machine and I could send you some
photos of mine are you interested? Skip Webb

---

Original Message

---

From: sjoblin001 [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=tCD87xugUlf97hSkfTp48PfVtyzk8GRKtUf7K10Gc1HP-WYmDkNorUu1mFCW_EEnyAiPzGJMHw]sjoblin@m...[/url
Sent: Friday, April 05, 2002 10:20 AM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Re: Hexapod servo stepping question


This doesn't help with your code problem, but I do know of a new
product coming out soon that may help. It is a 16 Serial Controller
from a company called Pololu (see www.pololu.com) They offer a more
robost version of Scott Edwards with control for speed. This way you
aren't burdening the stamp with trying to slow down the code
execution. The idea would be to send one command that tells the
servo not just where to go, but also how fast to move!

--- In basicstamps@y..., "kasaneus" <alex.dirks@w...> wrote:
>
> Hello all:
>
> I have created a hexapod from scratch and am now programming it
to
> walk. I am using a Basic stamp2 and 2 Scott Edwards SSC's for
serial
> leg control. I have succeded in programming the hexapod to perform
> pushups and a rough walking cycle. My issue is that I would like to
> slow the leg movements down, especially the "stride" part of the
leg
> walk cycle. I stripped my code down to just one leg to try
to "step"
> the servo's through a walk cycle, however only 1 servo of the leg
> seems to step through properly. I put debug commands throughout the
> code below to ensure correct values and that the "for/next" loops
as
> well as the "serout" commands have the correct values...all's well.
> What is absolutely stumping me is the fact that the 1st servo
> (servoposa(0)- the stride servo) steps slowly as the code dictates,
> but the 2nd servo (the lift servo) does not (it quickly goes to a
set
> position without stepping), even though the codes debug command
shows
> it stepping through the entire range of values. I have looked and
> tried all kinds of things with the code to solve it but to no
avail.
> I think another pair of eyes on the code below will spot the issue
> (s)? FYI, I have swapped connectors on the leg end to ensure proper
> functioning of the hardware....all ok. Any and all feedback would
be
> appreciated!
>
> Here is the code:
>
>
> '{$STAMP BS2}
> x var nib
> y var byte
> serposa var byte(2)
> serposb var byte(2)
> stride var byte
> liftl var byte
>
> stride = 70
> liftl = -20
>
> serposb(0)= 150
> serposb(1)= 90
> '

---

> serposa(0) = 150
> serposa(1) = 130
> gosub serout1
>
> stand: ' stride and lift routine values
>
> serposa(0) = serposb(0) + stride
> ' debug dec serposa(0)
> serposa(1) = serposb(1) + liftl
> ' debug dec serposa(1)
> gosub serout2
> end
>
> serout2: ' This will have the legs step through its values so they
> move slowly
>
> x=0
> for x=0 to 1
> ' debug dec x
> y=serposb(x)
> ' debug dec y
> for y=serposb(x) to serposa(x)
> serout 8,$4054,[noparse][[/noparse]255,x,y(x)]
> 'debug dec y
> pause 20
> next
> pause 1000
> next
> pause 500
> return
>
>
> serout1:' this will put the legs in a "home position" before the
walk
> cycle
>
> x=0
> for x=0 to 1
> serout 8,$4054,[noparse][[/noparse]255,x,serposa(x)]
> next
> pause 1000
> return


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Archiver

Absolutely! I would love to see pictures. Problem is, I haven't
started construction yet, so I can't send you pictures for quite a
long time. have you seen the MHEX Robot Walker or Frank Scott's
Hexapod Robots? These are two pretty good sites. Send any pictures
to sjoblin@m.... I have not yet settled on a mechanical design
yet. I would be most interested to know of your experiences. What
materials did you use, how many degrees of freedom does each leg
have, what routines are you using to turn the hexapod, etc.

Steve



--- In basicstamps@y..., "Webb, Skip (FL51)" <skip.webb@h...> wrote:
> I just created a hexapod from scratch and am now programming it
too!! I
> would love to see some photos of your machine and I could send you
some
> photos of mine are you interested? Skip Webb
>
>

---

Original Message

---

> From: sjoblin001 [noparse][[/noparse]mailto:sjoblin@m...]
> Sent: Friday, April 05, 2002 10:20 AM
> To: basicstamps@y...
> Subject: [noparse][[/noparse]basicstamps] Re: Hexapod servo stepping question
>
>
> This doesn't help with your code problem, but I do know of a new
> product coming out soon that may help. It is a 16 Serial
Controller
> from a company called Pololu (see www.pololu.com) They offer a
more
> robost version of Scott Edwards with control for speed. This way
you
> aren't burdening the stamp with trying to slow down the code
> execution. The idea would be to send one command that tells the
> servo not just where to go, but also how fast to move!
>
> --- In basicstamps@y..., "kasaneus" <alex.dirks@w...> wrote:
> >
> > Hello all:
> >
> > I have created a hexapod from scratch and am now programming it
> to
> > walk. I am using a Basic stamp2 and 2 Scott Edwards SSC's for
> serial
> > leg control. I have succeded in programming the hexapod to
perform
> > pushups and a rough walking cycle. My issue is that I would like
to
> > slow the leg movements down, especially the "stride" part of the
> leg
> > walk cycle. I stripped my code down to just one leg to try
> to "step"
> > the servo's through a walk cycle, however only 1 servo of the leg
> > seems to step through properly. I put debug commands throughout
the
> > code below to ensure correct values and that the "for/next" loops
> as
> > well as the "serout" commands have the correct values...all's
well.
> > What is absolutely stumping me is the fact that the 1st servo
> > (servoposa(0)- the stride servo) steps slowly as the code
dictates,
> > but the 2nd servo (the lift servo) does not (it quickly goes to a
> set
> > position without stepping), even though the codes debug command
> shows
> > it stepping through the entire range of values. I have looked and
> > tried all kinds of things with the code to solve it but to no
> avail.
> > I think another pair of eyes on the code below will spot the issue
> > (s)? FYI, I have swapped connectors on the leg end to ensure
proper
> > functioning of the hardware....all ok. Any and all feedback would
> be
> > appreciated!
> >
> > Here is the code:
> >
> >
> > '{$STAMP BS2}
> > x var nib
> > y var byte
> > serposa var byte(2)
> > serposb var byte(2)
> > stride var byte
> > liftl var byte
> >
> > stride = 70
> > liftl = -20
> >
> > serposb(0)= 150
> > serposb(1)= 90
> > '

---

> > serposa(0) = 150
> > serposa(1) = 130
> > gosub serout1
> >
> > stand: ' stride and lift routine values
> >
> > serposa(0) = serposb(0) + stride
> > ' debug dec serposa(0)
> > serposa(1) = serposb(1) + liftl
> > ' debug dec serposa(1)
> > gosub serout2
> > end
> >
> > serout2: ' This will have the legs step through its values so
they
> > move slowly
> >
> > x=0
> > for x=0 to 1
> > ' debug dec x
> > y=serposb(x)
> > ' debug dec y
> > for y=serposb(x) to serposa(x)
> > serout 8,$4054,[noparse][[/noparse]255,x,y(x)]
> > 'debug dec y
> > pause 20
> > next
> > pause 1000
> > next
> > pause 500
> > return
> >
> >
> > serout1:' this will put the legs in a "home position" before the
> walk
> > cycle
> >
> > x=0
> > for x=0 to 1
> > serout 8,$4054,[noparse][[/noparse]255,x,serposa(x)]
> > next
> > pause 1000
> > return
>
>
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> Body of the message will be ignored.
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