Body' state change

1) There is a kinematic engine, which makes any kind of motions [1]. See also examples [2]
2) Forces and torques can be recordered by ForceTorqueRecorder [3]

[1] http://bazaar.launchpad.net/~yade-dev/yade/trunk/view/head:/pkg/common/KinematicEngines.hpp
[2] http://bazaar.launchpad.net/~yade-dev/yade/trunk/view/head:/examples/packs/packs.py
[3] http://bazaar.launchpad.net/~yade-dev/yade/trunk/view/head:/pkg/dem/ForceTorqueRecorder.hpp

Thansk agian Anton for the answer.

Hi Anton,
I took a look in the example that you sent me and tried to change it. My goal is that I can change for example the angular velocity of the RotationEngine at each iterPeriod. I tried it:

rotvel=0
O.engines=[
 #SubdomainBalancer(colorize=True,initRun=True,iterPeriod=100),
 ForceResetter(),
 InsertionSortCollider([Bo1_Sphere_Aabb(),Bo1_Facet_Aabb(),Bo1_Wall_Aabb()],label='collider'),
 InteractionLoop(
  [Ig2_Sphere_Sphere_ScGeom(),Ig2_Facet_Sphere_ScGeom(),Ig2_Wall_Sphere_ScGeom()],
  [Ip2_FrictMat_FrictMat_FrictPhys()],
  [Law2_ScGeom_FrictPhys_CundallStrack()],
 ),
 GravityEngine(gravity=(1e-2,1e-2,-1000)),
 NewtonIntegrator(damping=.1,exactAsphericalRot=True),
 RotationEngine(
  ids=rotateIDs,
  angularVelocity=rotvel,
  rotationAxis=[0,-1,0],
  rotateAroundZero=1,
  zeroPoint=[-7.0,-6.0,-5.0]),
 HarmonicMotionEngine(A=[0,0,0.5], f=[0,0,20.0], fi = [0.0,0.0,pi], ids = vibrationPlate),
 HarmonicRotationEngine(A=0.2, f=100.0, fi = pi, rotationAxis=[1.0,0.0,0.0], rotateAroundZero = True, zeroPoint = [-15.0,3.0,-7.0], ids = vibrationRotationPlate),
     PyRunner(command='rotation()',iterPeriod=100)
]
def rotation():
    global rotvel
    rotvel = 100

but the value of rotvel seems to be always 0. How can I change then a variable located inside of the Engine?
Thanks, Daniela

I think that you can use labels:

O.engines = [
...
SomeEngine(...,label='sEngine')
...
]

sEngine.someParameter = value

good luck
Jan

______________________________________________________________
> Od: "Daniela" <email address hidden>
> Komu: <email address hidden>
> Datum: 06.07.2011 15:11
> Předmět: Re: [Yade-users] [Question #163736]: Body' state change
>
>Question #163736 on Yade changed:
>https://answers.launchpad.net/yade/+question/163736
>
> Status: Solved => Open
>
>Daniela is still having a problem:
>Hi Anton,
>I took a look in the example that you sent me and tried to change it. My goal is that I can change for example the angular velocity of the RotationEngine at each iterPeriod. I tried it:
>
>rotvel=0
>O.engines=[
> #SubdomainBalancer(colorize=True,initRun=True,iterPeriod=100),
> ForceResetter(),
> InsertionSortCollider([Bo1_Sphere_Aabb(),Bo1_Facet_Aabb(),Bo1_Wall_Aabb()],label='collider'),
> InteractionLoop(
> [Ig2_Sphere_Sphere_ScGeom(),Ig2_Facet_Sphere_ScGeom(),Ig2_Wall_Sphere_ScGeom()],
> [Ip2_FrictMat_FrictMat_FrictPhys()],
> [Law2_ScGeom_FrictPhys_CundallStrack()],
> ),
> GravityEngine(gravity=(1e-2,1e-2,-1000)),
> NewtonIntegrator(damping=.1,exactAsphericalRot=True),
> RotationEngine(
> ids=rotateIDs,
> angularVelocity=rotvel,
> rotationAxis=[0,-1,0],
> rotateAroundZero=1,
> zeroPoint=[-7.0,-6.0,-5.0]),
> HarmonicMotionEngine(A=[0,0,0.5], f=[0,0,20.0], fi = [0.0,0.0,pi], ids = vibrationPlate),
> HarmonicRotationEngine(A=0.2, f=100.0, fi = pi, rotationAxis=[1.0,0.0,0.0], rotateAroundZero = True, zeroPoint = [-15.0,3.0,-7.0], ids = vibrationRotationPlate),
> PyRunner(command='rotation()',iterPeriod=100)
>]
>def rotation():
> global rotvel
> rotvel = 100
>
>but the value of rotvel seems to be always 0. How can I change then a variable located inside of the Engine?
>Thanks, Daniela
>
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Hi Jan, it works with labels. Thanks!
I still have two questions:

1. I created a RotationEngine and a TranslationEngine, both with the same id, as want that a body (obtained from a mesh for example) has translational and rotational movement. But I see that just the one that is defined in the second place affects the body in the simulation. I saw that there is a CombinedKinematicEngine, but I am not sure if I should use it for this case. Anyway, how should I proceed in order to have the rotation and translation engines acting on the body?

2. I want to change the position and orientation of the body at some iterations. Can I do it using some Engine? I cannot imagine that I can do this using the TranslationEngine, as with this Engine I can define just the velocity.
When I include the body with O.bodies.append(YMPORT.GMSH("file.mesh",shift=,orientation=), I can define the orientation using Quaternion and the position using shift. I though that I could may bechange these variables, but I am also not sure because then I would need to reload the mesh every time that I change their values.

So, I would be grateful if you could help me with these questions.
Thanks in advance, Daniela

>1. I created a RotationEngine and a TranslationEngine, both with the
>same id, as want that a body (obtained from a mesh for example) has
>translational and rotational movement. But I see that just the one that
>is defined in the second place affects the body in the simulation. I saw
>that there is a CombinedKinematicEngine, but I am not sure if I should
>use it for this case. Anyway, how should I proceed in order to have the
>rotation and translation engines acting on the body?
O.engines = [
...
RotationEngine(...) + TranslationalEngine(...)
...
]

>
>2. I want to change the position and orientation of the body at some iterations. Can I do it using some Engine? I cannot imagine that I can do this using the TranslationEngine, as with this Engine I can define just the velocity.
O.bodies[...].state.pos = vector3(a,b,c)
but I am not sure if this works or not...

Jan

Hi Jan, thanks again for the help.
It works what you suggested, but I still have some problems:

1. As I don't want to load the mesh in the begin of the simulation, I wrote a PyRunner that checks the unbalancedForce and loads the mesh. Inside of the def function I defined the new engine using O.engines = O.engine+[RotationEngine(...,label='rotEng') + TranslationalEngine(...,label='transEng')] . But the problem now is that when I use the label to change some parameter from this engine, I receive the message: NameError: global name 'rotEng' is not defined. I tried to define the both labels as global, but it did not work. Any idea what I am doing wrong?

2.I also created a PyRunner to change the position of the body. The body is for example defined as:
body1=O.bodies.append(geom.facetCylinder((0,3,2),...)
It tried to make this
for b in O.bodies:
        if (b in body1):b.state.pos = Vector3(1,1,1)
but it does not work. If I write body1.id, the message that I receive says that list don't have ids.
How could I then change the position of the body1?

Thansk a lot. Daniela

Hi, the second problem I got to solve: if (b.id in body1):b.state.pos = Vector3(1,1,1)

Hi,
actually I have a file containing information about position, velocity, orientation and angular velocity for a body for many time steps. In this sense, what I need is to "tell" the body in yade these values during the simulation. I suppose that I could do it using the RotationEngine and the TranslationEngine, because then I could already define at least the velocity and the angular velocity. But I have 2 problems here:
1. when I make RotationEngine(...,label='rotEng')+TranslationEngine(...,label='transEng') and try to define for example rotEng.angularVelocity=10, I receive the message: NameError: global name 'rotEng' is not defined. The same with transEng. It seems to be a problem with the + sign. But why?
2. the zeroPoint must change, as the body also has a translation movement. Actually I could just give it the value of the position, but I still have the problem described above when I write rotEng.zeroPoint.
I hoppe someone can help me.
Thanks. Daniela

Hi,
I have tried to solve my problem about moving bodies using to steps. At first I give the values of the new position and orientation (mantaining velocity and angular velocity zero) and then the values of the velocity and angular velocity (this one, using a RotationEngine), something like this:

def changeValues():
    for i in idArray:
        O.bodies[int(i)].state.pos += Vector3(0.1,0,0)
        O.bodies[int(i)].state.vel = Vector3(0.,0,0)
        O.bodies[int(i)].state.angVel = Vector3(0,0,0)
    checker.command='changeValues2()'
    checker.iterPeriod=1

def changeValues2():
    for i in idArray:
        O.bodies[int(i)].state.vel = Vector3(10,0,0)
    rotEng.angularVelocity=100
    rotEng.rotationAxis=[0,1,0]
    rotEng.zeroPoint += (0.01,0,0)
    checker.command='changeValues()'
    checker.iterPeriod=1

I have tested it and it seems to work ok. Can you confirm if this is really compatible with the Yade algorithms?
Thansk in advance, Daniela.

Problem solved.

Thanks Chareyre, that solved my question.