pyode-user — PyODE User Discussions

Re: [Pyode-user] Pyrex not needed for installation?

[German L. M. <ger...@gm...>]

Thanks for the answer Ian. However, I think the the readme is misleading: if
it says "you don't need it to install and run PyODE", in a file included in
a source package, a user would expect just that. The term "develop" can have
quite different meanings.

Best regards,
Germán

On Wed, May 11, 2011 at 9:02 PM, Ian Mallett <geo...@gm...> wrote:

> On Wed, May 11, 2011 at 6:37 PM, German Larrain M. <
> ger...@gm...> wrote:
>
>> Hi. I'm an ODE user and wanted to check pyode's performance. Some time ago
>> I used Ubuntu's version of pyode and had some trouble so here I am trying to
>> compile this.
>>
>> The README file says:
>>
>>> - Pyrex 0.9.3 (or higher)
>>>   http://www.cosc.canterbury.ac.nz/~greg/python/Pyrex/
>>>   This is only required for PyODE development; you don't need it to
>>> install
>>>   and run PyODE.
>>>
>>
>> However, it seems I do need Pyrex to compile pyode:
>>
>>> python setup.py build
>>> INFO: <ode/ode.h> found in /usr/local/include
>>> INFO: Creating ode_trimesh.c
>>> pyrexc -o ode_trimesh.c -I. -Isrc src/ode.pyx
>>> sh: pyrexc: not found
>>> ERROR: An error occured while generating the C source file.
>>>
>>
>> I don't really know the development architecture of pyode, but, is there
>> anyway to keep the user from installing Pyrex? I'd rather use standard and
>> popular software (and pyrex doesn't look like it is).
>>
> So in the readme it says you only need PyRex to develop PyODE (that is, to
> compile the C files).  If you're going to be using it (i.e., using the
> Python builds), then you don't need PyRex.
>
> Ian
>



-- 
Germán Larrain

[Pyode-user] Pyrex not needed for installation?

[German L. M. <ger...@gm...>]

Hi. I'm an ODE user and wanted to check pyode's performance. Some time ago I
used Ubuntu's version of pyode and had some trouble so here I am trying to
compile this.

The README file says:

> - Pyrex 0.9.3 (or higher)
>   http://www.cosc.canterbury.ac.nz/~greg/python/Pyrex/
>   This is only required for PyODE development; you don't need it to install
>   and run PyODE.
>

However, it seems I do need Pyrex to compile pyode:

> python setup.py build
> INFO: <ode/ode.h> found in /usr/local/include
> INFO: Creating ode_trimesh.c
> pyrexc -o ode_trimesh.c -I. -Isrc src/ode.pyx
> sh: pyrexc: not found
> ERROR: An error occured while generating the C source file.
>

I don't really know the development architecture of pyode, but, is there
anyway to keep the user from installing Pyrex? I'd rather use standard and
popular software (and pyrex doesn't look like it is).

Thanks,
Germán
-- 
Germán Larrain

Re: [Pyode-user] Tutorial 3 - ODE internal error

[Ethan Glasser-C. <gl...@cs...>]

On 04/10/2011 05:55 PM, German Larrain M. wrote:
> Hi. I'm a new user of pyode and I was trying to run the examples 
> included the pythod-pyode-doc DEB package available in the Ubuntu 
> repositories.
>
> Tutorials 1 and 2 worked fine, but 3 fails every time I run it. The 
> weird thing is that the error appears after the explosion, but not 
> necessarily at the exact time. When it happens, the window closes and 
> the following message is printed

It looks like this could be caused by a lot of different kinds of 
problems with the simulation itself.  It runs fine on my machine 
(10.10-based, 32 bit).  I wonder if maybe there's a problem with the 
.debs available in the Ubuntu repositories -- built with the wrong 
precision or something?  Could you try building pyode yourself?

Ethan

Re: [Pyode-user] Tutorial 3 - ODE internal error

[German L. M. <ger...@gm...>]

Hi Ethan, thanks for your answer.

I have the following packages installed:
libode1: 2:0.11.1-3
libode-dev: 2:0.11.1-3 both of which seem to be the double-precision
version.
python-pyode: 1.2.0-4+cvs20090320

I will try to build pyode from source, although I feel that may not be the
issue.

Thanks again,
German

On Mon, Apr 11, 2011 at 2:13 PM, Ethan Glasser-Camp <gl...@cs...>wrote:

> On 04/10/2011 05:55 PM, German Larrain M. wrote:
>
>> Hi. I'm a new user of pyode and I was trying to run the examples included
>> the pythod-pyode-doc DEB package available in the Ubuntu repositories.
>>
>> Tutorials 1 and 2 worked fine, but 3 fails every time I run it. The weird
>> thing is that the error appears after the explosion, but not necessarily at
>> the exact time. When it happens, the window closes and the following message
>> is printed
>>
>
> It looks like this could be caused by a lot of different kinds of problems
> with the simulation itself.  It runs fine on my machine (10.10-based, 32
> bit).  I wonder if maybe there's a problem with the .debs available in the
> Ubuntu repositories -- built with the wrong precision or something?  Could
> you try building pyode yourself?
>
> Ethan
>
>


-- 
Germán Larrain

[Pyode-user] Tutorial 3 - ODE internal error

[German L. M. <ger...@gm...>]

Hi. I'm a new user of pyode and I was trying to run the examples included
the pythod-pyode-doc DEB package available in the Ubuntu repositories.

Tutorials 1 and 2 worked fine, but 3 fails every time I run it. The weird
thing is that the error appears after the explosion, but not necessarily at
the exact time. When it happens, the window closes and the following message
is printed

ODE INTERNAL ERROR 1: assertion "bNormalizationResult" failed in
> _dNormalize4() [../../../../../include/ode/odemath.h]
> Aborted
>

In the ode-users google group some information related to that assertion and
normalization problems, although I don't have the required experience to
fully understand the issue, and hopefully fix it.

http://groups.google.com/group/ode-users/browse_thread/thread/733b2e7339aabadb
http://groups.google.com/group/ode-users/msg/f333e88eab4ecd5b

I'm running Ubuntu 10.04 32-bit.

Thanks for your help,
German

-- 
Germán Larrain

[Pyode-user] JointSetFeedback for contact joints

[Marc K. <mki...@ga...>]

Hi,

I've asked this question before, but didn't get a response and thought I
would try again.
I'm trying to get forces at a contact joint.  My original solution was to
add a fixed joint
and get feedback from it, however this is not accurate enough when I have
multiple bodies
colliding.  However, when I try to use setFeedback on one of my contact
joints, the
following error results:

ODE INTERNAL ERROR 2: Bad argument(s) in dJointSetFeedback()
Aborted

I've done some checking and getting forces from contact joints in c++ seems
to work.
Any idea why this doesn't work in PyODE?  Thanks for any help or direction.

Sincerely,

Marc Killpack




On Sun, Jan 16, 2011 at 4:45 AM, Ethan Glasser-Camp <gl...@cs...>wrote:

> Hi! Sorry about the delay -- it's hard for me to find free time these days.
> I'm not really familiar with vpython so I may be vastly misinterpreting the
> function of your program.
>
>
> On 01/11/2011 03:17 PM, Marc Killpack wrote:
>
>> I've been trying to make a simple robot simulator which includes
>> collisions.  I'm getting weird
>> behavior though and wondered if I'm just making a dumb mistake.  I want
>> some objects that are
>> fixed in the environment.  From other examples and from archived questions
>> on the list it seems like
>> the best way to do this is using geometry objects that are not associated
>> with a body.  The only
>> collision that works so far is if I collide with the floor plane that is
>> defined as a fixed geometry.
>> I've attached my file that uses vpython for visualization and I had the
>> following questions if anyone
>> is willing:
>>
>> 1)If I set a tall square in place, different sizes will result in
>> collisions while smaller sizes do not, why?
>> (Try changing width and length of square to 0.1 in line 56 of .py file to
>> reproduce this)
>>
>
> It looks like body1, your robot arm, is not being rotated. If I understand
> correctly, this means that the capsule is extending along the Z-axis,
> whereas you are drawing it as extending along the X-axis. That is to say,
> your joint is not swinging the capsule like the arm of a turnstile, but more
> like the head of a hammer. I think the box obstacle is sufficiently wide
> that the capsule hits it anyhow, but if it is only 0.1, it fits "inside" the
> the radius of the hammer swing. To fix this, I put:
>
> body1.setRotation([0, 0, 1, 0, 1, 0, -1, 0, 0])
>
> Just after your body1.setPosition() call, before adding the geom. (A 90
> degree rotation around the Y axis, to exchange the X and Z axes, to make
> your visualization line up with the simulation.) Now a collision always
> happens.
>
>
>  Also, if I change the bounciness in the collision callback function (line
>> 28), it seems to have no effect
>> on the collision, why?
>>
>
> I'm guessing the motor on the joint is sufficiently powerful to keep
> pressing the body against the obstacle. Try changing MaxForce to 0 after the
> first time step (at the end of the while loop), so that the body has an
> initial velocity. You'll definitely see a bounce, and it will definitely be
> different for different bouncinesses.
>
>
>  2)I can place a geometry object that is a capped cylinder in the
>> environment but how do I orient it?  I tried
>> setting the rotation, but still couldn't get a collision to occur.  Change
>> "OBSTACLE = 2" on line 9 to see this.
>>
>
> This looks right to me, and once I added the rotation of the body (as per
> point 1), this caused collisions.
>
>
>  3)If I want forces from the collision, it seems that I have to have the
>> obstacle be associated with a body
>> as well, is that true?  If so, what kind of hinge or connection should I
>> use?  I tried a fixed joint to the
>> environment but that also did weird things.
>>
> I don't think this is true. Can you explain further?
>
> Ethan
>
>

Re: [Pyode-user] collision woes

[Ethan Glasser-C. <gl...@cs...>]

On 01/17/2011 07:07 AM, Marc Killpack wrote:
> Sorry one more follow-up question,
>
> What does setting the default axis in a Mass object do if it doesn't 
> define the direction of the associated body?  For example,
>
> M = ode.Mass()
> M.setCappedCylinder(10, /direction (x-axis = 1)/, /radius/, /length/)
> body1.setMass(M)
> body1.setPosition((/some position x, y, z)/)

Setting stuff on Mass objects is basically just to define physical 
simulation properties like center of mass, moment of inertia, etc. Try 
printing a Mass object some time, and you'll see all it defines. It has 
nothing to do with the collision detection or other rigid body functions 
(position, rotation, joints, etc.).

Ethan

Re: [Pyode-user] collision woes

[Marc K. <mki...@ga...>]

Sorry one more follow-up question,

What does setting the default axis in a Mass object do if it doesn't define
the direction of the associated body?  For example,

M = ode.Mass()
M.setCappedCylinder(10, *direction (x-axis = 1)*, *radius*, *length*)
body1.setMass(M)
body1.setPosition((*some position x, y, z)*)

I set the mass of my links such that they would be distributed along the
x-axis but is it true that this does not orient the body
along the x-axis?

Thank you again.

marc



On Mon, Jan 17, 2011 at 6:43 AM, Marc Killpack <mki...@ga...>wrote:

> Ethan,
>
> Regardless of the delay, I really appreciate the response.  Your solution
> was exactly correct and cleared up my collision problems.
>
> I was confused about the initial orientation given to created cylinder
> bodies.  Also, although rotation about the center of mass for each body
> makes the most sense, I was confused by the fact that all coordinates (both
> used for setting and returning a body's state) are in a global frame.  In
> any case, works great now, thank you.
>
> To explain my last point more, I'm interested in getting forces that result
> from collisions, but when I tried to use "setFeedback" with my contact
> joints, it threw the following error:
>
> ODE INTERNAL ERROR 2: Bad argument(s) in dJointSetFeedback()
> Aborted
>
> I'd seen this in other threads and thought this meant that getting reaction
> forces from the contact was not possible.  Also, I assumed that because the
> geometry has no "mass", that getting contact forces from the collision with
> a body and a geometry was also not possible.  So I made an extra body for my
> obstacle that is rigidly fixed to the environment with a fixed joint that
> will give forces induced by the collision somewhere along the body.  If
> there is a better/other way, I'd be happy to hear about it.
>
> Thanks again for the help and course correction.
>
>
> Sincerely,
>
> Marc Killpack
> Healthcare Robotics Lab - Georgia Tech
>
>
>
> On Sun, Jan 16, 2011 at 4:45 AM, Ethan Glasser-Camp <gl...@cs...>wrote:
>
>> Hi! Sorry about the delay -- it's hard for me to find free time these
>> days. I'm not really familiar with vpython so I may be vastly
>> misinterpreting the function of your program.
>>
>>
>> On 01/11/2011 03:17 PM, Marc Killpack wrote:
>>
>>> I've been trying to make a simple robot simulator which includes
>>> collisions.  I'm getting weird
>>> behavior though and wondered if I'm just making a dumb mistake.  I want
>>> some objects that are
>>> fixed in the environment.  From other examples and from archived
>>> questions on the list it seems like
>>> the best way to do this is using geometry objects that are not associated
>>> with a body.  The only
>>> collision that works so far is if I collide with the floor plane that is
>>> defined as a fixed geometry.
>>> I've attached my file that uses vpython for visualization and I had the
>>> following questions if anyone
>>> is willing:
>>>
>>> 1)If I set a tall square in place, different sizes will result in
>>> collisions while smaller sizes do not, why?
>>> (Try changing width and length of square to 0.1 in line 56 of .py file to
>>> reproduce this)
>>>
>>
>> It looks like body1, your robot arm, is not being rotated. If I understand
>> correctly, this means that the capsule is extending along the Z-axis,
>> whereas you are drawing it as extending along the X-axis. That is to say,
>> your joint is not swinging the capsule like the arm of a turnstile, but more
>> like the head of a hammer. I think the box obstacle is sufficiently wide
>> that the capsule hits it anyhow, but if it is only 0.1, it fits "inside" the
>> the radius of the hammer swing. To fix this, I put:
>>
>> body1.setRotation([0, 0, 1, 0, 1, 0, -1, 0, 0])
>>
>> Just after your body1.setPosition() call, before adding the geom. (A 90
>> degree rotation around the Y axis, to exchange the X and Z axes, to make
>> your visualization line up with the simulation.) Now a collision always
>> happens.
>>
>>
>>  Also, if I change the bounciness in the collision callback function (line
>>> 28), it seems to have no effect
>>> on the collision, why?
>>>
>>
>> I'm guessing the motor on the joint is sufficiently powerful to keep
>> pressing the body against the obstacle. Try changing MaxForce to 0 after the
>> first time step (at the end of the while loop), so that the body has an
>> initial velocity. You'll definitely see a bounce, and it will definitely be
>> different for different bouncinesses.
>>
>>
>>  2)I can place a geometry object that is a capped cylinder in the
>>> environment but how do I orient it?  I tried
>>> setting the rotation, but still couldn't get a collision to occur.
>>>  Change "OBSTACLE = 2" on line 9 to see this.
>>>
>>
>> This looks right to me, and once I added the rotation of the body (as per
>> point 1), this caused collisions.
>>
>>
>>  3)If I want forces from the collision, it seems that I have to have the
>>> obstacle be associated with a body
>>> as well, is that true?  If so, what kind of hinge or connection should I
>>> use?  I tried a fixed joint to the
>>> environment but that also did weird things.
>>>
>> I don't think this is true. Can you explain further?
>>
>> Ethan
>>
>>
>                                                   <#12d93c9ab7c40535_12d938cf63e95412_>
> <#12d93c9ab7c40535_12d938cf63e95412_>
> <#12d93c9ab7c40535_12d938cf63e95412_>       <#12d93c9ab7c40535_12d938cf63e95412_>
>

Re: [Pyode-user] collision woes

[Marc K. <mki...@ga...>]

Ethan,

Regardless of the delay, I really appreciate the response.  Your solution
was exactly correct and cleared up my collision problems.

I was confused about the initial orientation given to created cylinder
bodies.  Also, although rotation about the center of mass for each body
makes the most sense, I was confused by the fact that all coordinates (both
used for setting and returning a body's state) are in a global frame.  In
any case, works great now, thank you.

To explain my last point more, I'm interested in getting forces that result
from collisions, but when I tried to use "setFeedback" with my contact
joints, it threw the following error:

ODE INTERNAL ERROR 2: Bad argument(s) in dJointSetFeedback()
Aborted

I'd seen this in other threads and thought this meant that getting reaction
forces from the contact was not possible.  Also, I assumed that because the
geometry has no "mass", that getting contact forces from the collision with
a body and a geometry was also not possible.  So I made an extra body for my
obstacle that is rigidly fixed to the environment with a fixed joint that
will give forces induced by the collision somewhere along the body.  If
there is a better/other way, I'd be happy to hear about it.

Thanks again for the help and course correction.

Sincerely,

Marc Killpack
Healthcare Robotics Lab - Georgia Tech



On Sun, Jan 16, 2011 at 4:45 AM, Ethan Glasser-Camp <gl...@cs...>wrote:

> Hi! Sorry about the delay -- it's hard for me to find free time these days.
> I'm not really familiar with vpython so I may be vastly misinterpreting the
> function of your program.
>
>
> On 01/11/2011 03:17 PM, Marc Killpack wrote:
>
>> I've been trying to make a simple robot simulator which includes
>> collisions.  I'm getting weird
>> behavior though and wondered if I'm just making a dumb mistake.  I want
>> some objects that are
>> fixed in the environment.  From other examples and from archived questions
>> on the list it seems like
>> the best way to do this is using geometry objects that are not associated
>> with a body.  The only
>> collision that works so far is if I collide with the floor plane that is
>> defined as a fixed geometry.
>> I've attached my file that uses vpython for visualization and I had the
>> following questions if anyone
>> is willing:
>>
>> 1)If I set a tall square in place, different sizes will result in
>> collisions while smaller sizes do not, why?
>> (Try changing width and length of square to 0.1 in line 56 of .py file to
>> reproduce this)
>>
>
> It looks like body1, your robot arm, is not being rotated. If I understand
> correctly, this means that the capsule is extending along the Z-axis,
> whereas you are drawing it as extending along the X-axis. That is to say,
> your joint is not swinging the capsule like the arm of a turnstile, but more
> like the head of a hammer. I think the box obstacle is sufficiently wide
> that the capsule hits it anyhow, but if it is only 0.1, it fits "inside" the
> the radius of the hammer swing. To fix this, I put:
>
> body1.setRotation([0, 0, 1, 0, 1, 0, -1, 0, 0])
>
> Just after your body1.setPosition() call, before adding the geom. (A 90
> degree rotation around the Y axis, to exchange the X and Z axes, to make
> your visualization line up with the simulation.) Now a collision always
> happens.
>
>
>  Also, if I change the bounciness in the collision callback function (line
>> 28), it seems to have no effect
>> on the collision, why?
>>
>
> I'm guessing the motor on the joint is sufficiently powerful to keep
> pressing the body against the obstacle. Try changing MaxForce to 0 after the
> first time step (at the end of the while loop), so that the body has an
> initial velocity. You'll definitely see a bounce, and it will definitely be
> different for different bouncinesses.
>
>
>  2)I can place a geometry object that is a capped cylinder in the
>> environment but how do I orient it?  I tried
>> setting the rotation, but still couldn't get a collision to occur.  Change
>> "OBSTACLE = 2" on line 9 to see this.
>>
>
> This looks right to me, and once I added the rotation of the body (as per
> point 1), this caused collisions.
>
>
>  3)If I want forces from the collision, it seems that I have to have the
>> obstacle be associated with a body
>> as well, is that true?  If so, what kind of hinge or connection should I
>> use?  I tried a fixed joint to the
>> environment but that also did weird things.
>>
> I don't think this is true. Can you explain further?
>
> Ethan
>
>

<#12d938cf63e95412_>
<#12d938cf63e95412_>             <#12d938cf63e95412_>       <#12d938cf63e95412_>

Re: [Pyode-user] collision woes

[Ethan Glasser-C. <gl...@cs...>]

Hi! Sorry about the delay -- it's hard for me to find free time these 
days. I'm not really familiar with vpython so I may be vastly 
misinterpreting the function of your program.

On 01/11/2011 03:17 PM, Marc Killpack wrote:
> I've been trying to make a simple robot simulator which includes 
> collisions.  I'm getting weird
> behavior though and wondered if I'm just making a dumb mistake.  I 
> want some objects that are
> fixed in the environment.  From other examples and from archived 
> questions on the list it seems like
> the best way to do this is using geometry objects that are not 
> associated with a body.  The only
> collision that works so far is if I collide with the floor plane that 
> is defined as a fixed geometry.
> I've attached my file that uses vpython for visualization and I had 
> the following questions if anyone
> is willing:
>
> 1)If I set a tall square in place, different sizes will result in 
> collisions while smaller sizes do not, why?
> (Try changing width and length of square to 0.1 in line 56 of .py file 
> to reproduce this)

It looks like body1, your robot arm, is not being rotated. If I 
understand correctly, this means that the capsule is extending along the 
Z-axis, whereas you are drawing it as extending along the X-axis. That 
is to say, your joint is not swinging the capsule like the arm of a 
turnstile, but more like the head of a hammer. I think the box obstacle 
is sufficiently wide that the capsule hits it anyhow, but if it is only 
0.1, it fits "inside" the the radius of the hammer swing. To fix this, I 
put:

body1.setRotation([0, 0, 1, 0, 1, 0, -1, 0, 0])

Just after your body1.setPosition() call, before adding the geom. (A 90 
degree rotation around the Y axis, to exchange the X and Z axes, to make 
your visualization line up with the simulation.) Now a collision always 
happens.

> Also, if I change the bounciness in the collision callback function 
> (line 28), it seems to have no effect
> on the collision, why?

I'm guessing the motor on the joint is sufficiently powerful to keep 
pressing the body against the obstacle. Try changing MaxForce to 0 after 
the first time step (at the end of the while loop), so that the body has 
an initial velocity. You'll definitely see a bounce, and it will 
definitely be different for different bouncinesses.

> 2)I can place a geometry object that is a capped cylinder in the 
> environment but how do I orient it?  I tried
> setting the rotation, but still couldn't get a collision to occur.  
> Change "OBSTACLE = 2" on line 9 to see this.

This looks right to me, and once I added the rotation of the body (as 
per point 1), this caused collisions.

> 3)If I want forces from the collision, it seems that I have to have 
> the obstacle be associated with a body
> as well, is that true?  If so, what kind of hinge or connection should 
> I use?  I tried a fixed joint to the
> environment but that also did weird things.
I don't think this is true. Can you explain further?

Ethan

[Pyode-user] collision woes

[Marc K. <mki...@ga...>]

Hi,

Extremely sorry if this is a repeat, but I think the first email didn't go
through.

I've been trying to make a simple robot simulator which includes
collisions.  I'm getting weird
behavior though and wondered if I'm just making a dumb mistake.  I want some
objects that are
fixed in the environment.  From other examples and from archived questions
on the list it seems like
the best way to do this is using geometry objects that are not associated
with a body.  The only
collision that works so far is if I collide with the floor plane that is
defined as a fixed geometry.
I've attached my file that uses vpython for visualization and I had the
following questions if anyone
is willing:

1)If I set a tall square in place, different sizes will result in collisions
while smaller sizes do not, why?
(Try changing width and length of square to 0.1 in line 56 of .py file to
reproduce this)
Also, if I change the bounciness in the collision callback function (line
28), it seems to have no effect
on the collision, why?

2)I can place a geometry object that is a capped cylinder in the environment
but how do I orient it?  I tried
setting the rotation, but still couldn't get a collision to occur.  Change
"OBSTACLE = 2" on line 9 to see this.

3)If I want forces from the collision, it seems that I have to have the
obstacle be associated with a body
as well, is that true?  If so, what kind of hinge or connection should I
use?  I tried a fixed joint to the
environment but that also did weird things.

Any help on any one of the questions would be very much appreciated.  Thanks
for your time.

Sincerely,

Marc Killpack
Healthcare Robotics Lab - Georgia Tech

Re: [Pyode-user] How can I translate the FixedJoint Position?

[Moster M. <mos...@ho...>]

Now, I used .setPosition((x,y,z)) and then call the setFixed function.
That works, but I don't know what influence will occur on my system, I means another bugs.

Thank you for your reply 


 
Best regards,
 
Sukrit Manokhatiphaisan
Master degree student of
Institute of FIeld roBOtics(FIBO)
King Mongkut's University of Technology Thonburi
Administrator of
Hubei Jingshan Light Industrial Machinery (Thailand) Co.,Ltd

Email: mos...@ho..., mos...@gm...
Tel: 085-988-8628
   
 


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Date: Wed, 5 Jan 2011 12:28:12 -0500
From: gl...@cs...
To: mos...@ho...
CC: pyo...@li...
Subject: Re: [Pyode-user] How can I translate the FixedJoint Position?



  


    
  
  
    On 12/25/2010 02:27 AM, Moster Manokhatipaisarn wrote:
    
      
      My code as follow:

      

      join = ode.FixedJoint(self.visualWorld.odeworld)

      join.attach(self.vObjList[0].body, obj.body)

      

      However, I want to translate the fixedjoint position.

      I try to translate but the result is not make sense.

      

      It would be better if I can detach this joint, translate it and
      attach again.

      But I don't know how to detach this joint

    
    

    I'm not sure I understand your question. You want to have two
    objects fixed together, but periodically change their positions?

    

    ODE does not provide a function to detach joints. Since FixedJoints
    don't have any state, you could probably destroy the joint, move the
    bodies, and create another one. However, be aware that the manual
    says:

    

    "Using this joint is almost never a good idea in practice, except
    when debugging. If you need two bodies to be glued together it is
    better to represent that as a single body."

    

    Hope this helps.

    

    Ethan

    
 		 	   		  

Re: [Pyode-user] How can I translate the FixedJoint Position?

[Ethan Glasser-C. <gl...@cs...>]

On 12/25/2010 02:27 AM, Moster Manokhatipaisarn wrote:
> My code as follow:
>
> join = ode.FixedJoint(self.visualWorld.odeworld)
> join.attach(self.vObjList[0].body, obj.body)
>
> However, I want to translate the fixedjoint position.
> I try to translate but the result is not make sense.
>
> It would be better if I can detach this joint, translate it and attach 
> again.
> But I don't know how to detach this joint

I'm not sure I understand your question. You want to have two objects 
fixed together, but periodically change their positions?

ODE does not provide a function to detach joints. Since FixedJoints 
don't have any state, you could probably destroy the joint, move the 
bodies, and create another one. However, be aware that the manual says:

"Using this joint is almost never a good idea in practice, except when 
debugging. If you need two bodies to be glued together it is better to 
represent that as a single body."

Hope this helps.

Ethan

[Pyode-user] How can I translate the FixedJoint Position?

[Moster M. <mos...@ho...>]

My code as follow:

join = ode.FixedJoint(self.visualWorld.odeworld)
join.attach(self.vObjList[0].body, obj.body)

However, I want to translate the fixedjoint position.
I try to translate but the result is not make sense.

It would be better if I can detach this joint, translate it and attach again.
But I don't know how to detach this joint


 
Best regards,
 
Sukrit Manokhatiphaisan
Master degree student of
Institute of FIeld roBOtics(FIBO)
King Mongkut's University of Technology Thonburi
Administrator of
Hubei Jingshan Light Industrial Machinery (Thailand) Co.,Ltd

Email: mos...@ho..., mos...@gm...
Tel: 085-988-8628
   
 


<< Confidential Note >> 
 
If  you are not the intended recipient, please do not read, copy, use or disclose the contents of this communication to others.  This e-mail message (including any attachment) is intended only for the individual(s) or entity named above and others who have been specifically authorized to receive it.  Please notify the sender that you have received this email in error by replying to the email. Please then delete the email and any copies of it. This information may be confidential and be subject to other privilege or any other immunity. 

 		 	   		  

[Pyode-user] How to create point mass (small radius) in visual world?

[Moster M. <mos...@ho...>]

Now, I use following code:

pointMass_grams = 200
self.radius = 0.01

self.M = ode.Mass()
self.M.setSphereTotal(pointMass_grams, self.radius)
self.geom = ode.GeomSphere(vw.odespace, self.radius)
self.body = ode.Body(vw.odeworld)
self.body.setMass(self.M)
self.geom.setBody(self.body)

When I printed out self.M the result is not show as I think...
Total mass from the result is changed when I vary radius values
I just want to create point mass in ode space without concerning inertia tensor.
 

 
Best regards,
 
Sukrit Manokhatiphaisan
Master degree student of
Institute of FIeld roBOtics(FIBO)
King Mongkut's University of Technology Thonburi
Administrator of
Hubei Jingshan Light Industrial Machinery (Thailand) Co.,Ltd

Email: mos...@ho..., mos...@gm...
Tel: 085-988-8628
   
 


<< Confidential Note >> 
 
If  you are not the intended recipient, please do not read, copy, use or disclose the contents of this communication to others.  This e-mail message (including any attachment) is intended only for the individual(s) or entity named above and others who have been specifically authorized to receive it.  Please notify the sender that you have received this email in error by replying to the email. Please then delete the email and any copies of it. This information may be confidential and be subject to other privilege or any other immunity. 

 		 	   		  

[Pyode-user] Force/Torque

[Moster M. <mos...@ho...>]

Now, I am develop my system to simulate robot which contain servo motors
However, I am still confuse about force/torque in pyODE. 
I googled about how to set max force in hindgejoint.
I found that 
self.hindgejoint.setParam(ode.ParamFMax, F)

Anyway, I also want to set max torque on each vServos
How can I do that?

Thank you 

 
Best regards,
 
Sukrit Manokhatiphaisan
Master degree student of
Institute of FIeld roBOtics(FIBO)
King Mongkut's University of Technology Thonburi
Administrator of
Hubei Jingshan Light Industrial Machinery (Thailand) Co.,Ltd

Email: mos...@ho..., mos...@gm...
Tel: 085-988-8628
   
 


<< Confidential Note >> 
 
If  you are not the intended recipient, please do not read, copy, use or disclose the contents of this communication to others.  This e-mail message (including any attachment) is intended only for the individual(s) or entity named above and others who have been specifically authorized to receive it.  Please notify the sender that you have received this email in error by replying to the email. Please then delete the email and any copies of it. This information may be confidential and be subject to other privilege or any other immunity. 

 		 	   		  

Re: [Pyode-user] Just a simple question

[Diez B. R. <de...@we...>]

On Dec 1, 2010, at 2:54 PM, Moster Manokhatipaisarn wrote:

> What is the unit of force/torque in pyODE.
> And if I want to convert to Robotis unit how can I do.

None. Or whatever you chose. There are numerical reasons to keep things limited, but if you chose to have e.g. gravity at 9810 mm/s^2, it's up to you.

Diez

[Pyode-user] Just a simple question

[Moster M. <mos...@ho...>]

What is the unit of force/torque in pyODE.
And if I want to convert to Robotis unit how can I do.

Thank you ^^


 
Best regards,
 
Sukrit Manokhatiphaisan
Master degree student of
Institute of FIeld roBOtics(FIBO)
King Mongkut's University of Technology Thonburi
Administrator of
Hubei Jingshan Light Industrial Machinery (Thailand) Co.,Ltd

Email: mos...@ho..., mos...@gm...
Tel: 085-988-8628
   
 


<< Confidential Note >> 
 
If  you are not the intended recipient, please do not read, copy, use or disclose the contents of this communication to others.  This e-mail message (including any attachment) is intended only for the individual(s) or entity named above and others who have been specifically authorized to receive it.  Please notify the sender that you have received this email in error by replying to the email. Please then delete the email and any copies of it. This information may be confidential and be subject to other privilege or any other immunity. 

 		 	   		  

[Pyode-user] Class Inheritance in PyODE

[Scott P. <spr...@gm...>]

I have a question about class inheritance in PyODE.... how does it work?
I've tried to inherit the ode.Body class in my python code as follows:
        
        
        #!/usr/bin/env python
        
        import ode
        
        class Sphere(ode.Body):
          """Class representing a spherical rigid body"""
          
          def __init__(self, world, space, mass, radius):
            """Creates a new sphere and places it in the world"""
            
            # Create the base body class 
            #super(Sphere, self).__init__(world) # using old style
        classes?
            ode.Body.__init__(self, world)
            
            # Set up some initial required values for the sphere
            self.shape = "sphere"
            self.radius = radius
            self.volume = 4. / 3. * pi * radius ** 3.
            self.space = space 
            
            # Set up the main properties of the sphere
            self.setMass(mass)
            self.setRadius(radius)
            self.setGeom(space, radius)

However, when I attempt to instantiate my Sphere class, I get an error
complaining that the number of arguments I'm providing it are wrong,
even though I can clearly see that that is not the case. In fact, I can
only get my Sphere class to work at all if I recreate the
Sphere.__init__ function to accept the same number of arguments as
ode.Body.__init__. I tried out a couple of different ODE classes to see
if this is true of any others, and it appears to be true for all PyODE
classes. 

Can anyone show an example of using class inheritance with a PyODE base
class and/or explain to me why class inheritance doesn't work?

Re: [Pyode-user] Patch: adds ode.init() and fixes a few deprecation warnings from pyrexe.

[Kasper B. <kb...@gm...>]

On Mon, Nov 8, 2010 at 14:45, Ethan Glasser-Camp <gl...@cs...> wrote:
> I didn't see any patch, but pyode in git defines a function called
> ode.InitODE() which is called automatically on import.

It seems my message was held back for moderator approval because it
was too big. I guess the patch got lost in that process.

I have py-ode version 1.2.0. I checked the website
(http://pyode.sourceforge.net/) and it looked as if this was the
latest version. Anyway this version doesn't work with anything later
than ODE 0.8, partly because newer versions of ODE requires that
InitODE() is called before any other library function. My patch fixed
that but apparently someone beat me to it in the git version.

/Kasper

Re: [Pyode-user] Patch: adds ode.init() and fixes a few deprecation warnings from pyrexe.

[Ethan Glasser-C. <gl...@cs...>]

On 10/26/2010 11:10 AM, Kasper Bonne wrote:
> PyODE doesn't seem to support the latest version of the ode library
> because later versions of ode require you to initialize the library
> before using it.
>
> I've attached a patch that adds a library initialization function
> ode.init(). I can't say for sure if it fixes all compatibility issues
> but at least it fixed my problem. Just call ode.init() before any
> other ode-function and it should work with the latest version of the
> library (ode-0.11)
>    

Hi,

I didn't see any patch, but pyode in git defines a function called 
ode.InitODE() which is called automatically on import.

Ethan

[Pyode-user] Patch: adds ode.init() and fixes a few deprecation warnings from pyrexe.

[Kasper B. <kb...@gm...>]

Hi list

PyODE doesn't seem to support the latest version of the ode library
because later versions of ode require you to initialize the library
before using it.

I've attached a patch that adds a library initialization function
ode.init(). I can't say for sure if it fixes all compatibility issues
but at least it fixed my problem. Just call ode.init() before any
other ode-function and it should work with the latest version of the
library (ode-0.11)

Best
/Kasper

Re: [Pyode-user] Problem with PyODE object deallocation and XODE changes

[Ethan Glasser-C. <gl...@cs...>]

On 10/11/2010 09:32 AM, John Glover wrote:
> Hi Ethan,
>
> Sorry about the delay. Here you go.
>    

Hi,

These patches are now pushed, with vague and unhelpful commit messages. 
Thanks!

Ethan

Re: [Pyode-user] PyODE joint properties accessible as parameters

[Alexandru D. <al...@ci...>]

Hello Niels,

You should get the latest snapshot from the git repo and build it
yourself. That's not easy, because you also have to compile ODE and
specify a double precision.

The steps are roughly these:

1) Get the latest ODE from SVN and build it as static library in DOUBLE
precision. You have to fiddle with make files to achieve that.

2) Get the latest PyODE from the git mirror:
git clone git://pyode.git.sourceforge.net/gitroot/pyode/pyode
cd pyode
<edit setup.py to point to your ODE installation and specify double
precision>
python setup.py build
sudo python setup.py install

The project is listed in PyPI database, but "easy_install pyode" does not
work on my machine. I don't know why. Maybe some Python/Cython expert will
help.

If you use Windows, I'll build a new executable from the latest git snapshot.

Alex

> Thnx, but a short Question: How do i install the patch? -__-'
>
> I would like to use the Pistion joint but is does not work in my current
> installation.
>
>
>
>
>
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Re: [Pyode-user] PyODE joint properties accessible as parameters

[Niels <nie...@gm...>]

Thnx, but a short Question: How do i install the patch? -__-'

I would like to use the Pistion joint but is does not work in my current 
installation.