I'm getting very confused trying to setup my simulation correctly in PyDrake. What I want is to have an actuated robot (with e.g. an InverseDynamicsController on it) together with an object in the scene that the robot will manipulate. However, I'm struggling to sort out how to create and use the MultibodyPlant, SceneGraph, Context, Simulator combination correctly.
Here is roughly what I've tried to do:
builder = DiagramBuilder()
plant, scene_graph = AddMultibodyPlantSceneGraph(builder, time_step=1e-4)
parser = Parser(plant, scene_graph)
# Add my robot
robot = parser.AddModelFromFile(robot_urdf)
robot_base = plant.GetFrameByName('robot_base')
plant.WeldFrames(plant.world_frame(), robot_base)
# Add my object
parser.AddModelFromFile(FindResourceOrThrow("drake/my_object.urdf"))
plant.finalize()
# Add my controller
Kp = np.full(6, 100)
Ki = 2 * np.sqrt(Kp)
Kd = np.full(6, 1)
controller = builder.AddSystem(InverseDynamicsController(plant, Kp, Ki, Kd, False))
controller.set_name("sim_controller");
builder.Connect(plant.get_state_output_port(robot),
controller.get_input_port_estimated_state())
builder.Connect(controller.get_output_port_control(),
plant.get_actuation_input_port())
# Get the diagram, simulator, and contexts
diagram = builder.Build()
simulator = Simulator(diagram)
context = simulator.get_mutable_context()
plant_context = plant.GetMyContextFromRoot(context)
However, this has some undesirable qualities. First, as long as I've added the object, then I get this error:
Failure at systems/controllers/inverse_dynamics_controller.cc:32 in SetUp(): condition 'num_positions == dim' failed.
Second, with the object added, the object pose becomes part of my InverseKinematics problem, and when I do SetPositions with plant_context, I have to set both my arm joints AND the pose of the object, when I feel like I should only be setting the robot's joint positions with SetPositions.
I realize I've done something wrong with this setup, and I'm just wondering what is the correct way to have an instance of Simulator that I can run simulations with that has both an actuated robot, and a manipulable object? Am I supposed to create multiple plants? Multiple contexts? Who shares what with who?
I'd really appreciate some advice on this, or a pointer to an example. Drake is great, but I struggle to find minimal examples that do what I want.
Yes, you can add a separate MultibodyPlant for control. See https://github.com/RobotLocomotion/drake/blob/master/examples/planar_gripper/planar_gripper_simulation.cc for an example. The setup is similar to yours, though it's in C++. You can try mimicking the way the diagram is wired up there.
When you do have two plants, you want to call SetPositions on the simulation plant (not the control plant). You can set only the robot positions by using ModelInstanceIndex.
# Add my robot
robot = parser.AddModelFromFile(robot_urdf)
...
plant.SetPositions(plant_context, robot, robot_positions)
Related
[I have been trying many solutions posted here and there, yet I cannot make this work]
I have a python script on blender side exporting object rotations like this
m = obj.matrix_world.to_euler('XYZ')
rot = mathutils.Vector((math.degrees(m.x),math.degrees(m.y),math.degrees(m.z)))
on unreal side, still in python, setting up rotators for imported objects :
def createRotator(actor_rotation):
rotatorX = unreal.MathLibrary.rotator_from_axis_and_angle(unreal.Vector(0.1,0.0,0.0),actor_rotation.x)
rotatorY = unreal.MathLibrary.rotator_from_axis_and_angle(unreal.Vector(0.0,0.1,0.0),actor_rotation.y)
rotatorZ = unreal.MathLibrary.rotator_from_axis_and_angle(unreal.Vector(0.0,0.0,0.1),actor_rotation.z)
temp = unreal.MathLibrary.compose_rotators(rotatorX,rotatorY)
rotator = unreal.MathLibrary.compose_rotators(temp,rotatorZ)
return rotator
yet the objects are not placed correctly (in term of rotation) in unreal
I tried:
adding - in front of different rotation members in blender
flipping the order of the unreal rotators are combined in unreal
tried y=z and z=-y
tried z = -z or y=-y
(I could go on since I been busting my head on this for a whole week)
I been through so many posts, every answer is different, and none of them is working
can someone more clever than I am end my misery and tell me how to solve this ?
thanks
[edit:]
I spawn the actor like this
pos = unreal.Vector(float(row["posx"]),float(row["posy"]),float(row["posz"]))
rot = unreal.Vector(float(row["rotx"]),float(row["roty"]),float(row["rotz"]))
rotator = createRotator(rot)
staticMeshActor = unreal.EditorLevelLibrary.spawn_actor_from_object(staticMesh, pos, rotator)
How can I create a synapse in the NEURON simulator using its Python interface? I would like to create 2 Sections and connect them with a synapse, but there aren't any functions for it on the Section API or in the Section docs:
from neuron import h
src = h.Section(name="source")
dest = h.Section(name="destination")
In NEURON synapses are of the family of PointProcesses. You can insert a PointProcess into a Section by accessing it on the HocInterpreter and giving it a Segment on the Section. You then have to create a NetCon from a voltage pointer on the presynaptic Section (src(x)._ref_v) to the target point process:
from neuron import h
dest = h.Section(name="destination")
synapse = h.ExpSyn(sec(0.5))
src = h.Section(name="source")
connection = h.NetCon(src(0.5)._ref_v, synapse)
Make sure to keep references to each piece around or they get garbage collected. Also make sure that you set the proper connection.weight (it's an array, so usually connection.weight[0]) and that you set the proper attributes on the point process for it to function as well.
I'm attempting to use Autodesk Inventor's COM API to create a python script that will generate PDFs of a selection on Inventor Drawings, these PDFs will then be processed in particular ways that aren't important to my question. I'm using pywin32 to access the COM API, but I'm not particularly familiar with how COM APIs are used, and the pywin32 module.
This is the extent of the documentation for Inventor's API that I have been able to find (diagram of API Object Model Reference Document), and I have not been able to find documentation for the individual objects listed. As such, I'm basing my understanding of the use of these objects on what I can find from examples online (all in VB or iLogic - Inventor's own simple built-in language).
A big issue I'm coming up against is in creating the objects I'd like to use. Simplified example below:
from win32com.client import *
# user chooses file paths for open and save here...
drawing_filepath = ""
# Open Inventor application, and set visible (so I can tell it's opened for now)
app = Dispatch('Inventor.Application')
app.Visible = True
# Open the file to be saved as a pdf (returns a Document object)
app.Documents.Open(drawing_filepath)
# Cast the opened Document object to a DrawingDocument object (it is guaranteed to be a drawing)
drawing = CastTo(app.ActiveDocument, "DrawingDocument")
# Create and setup a print manager (so can use "Adobe PDF" printer to convert the drawings to PDF)
print_manager = ??? # How can I create this object
# I've tried:
# print_manager = Dispatch("Inventor.Application.Documents.DrawingDocument.DrawingPrintManager") #"Invalid class string"
# print_manager = drawing.DrawingPrintManager() #"object has no attribute 'DrawingPrintManger'
# print_manager = drawing.DrawingPrintManager # same as above
# print_manager = drawing.PrintManger # worked in the end
print_manager.Printer = "Adobe PDF"
print_manager.NumberOfCopies = 1
print_manager.ScaleMode = print_manager.PrintScaleModeEnum.kPrintFullScale
print_manager.PaperSize = print_manager.PrintSizeEnum.kPaperSizeA3
# Print PDF
print_manager.SubmitPrint()
So I can't figure out how to create a DrawingPrintManager to use! You can see I've avoided this issue when creating my DrawingDocument object, as I just happened to know that there is an ActiveDocument attribute that I can get from the application itself.
I also:
don't know what the full list of attributes and methods for DrawingPrintManager are, so I don't know how to set a save location
don't know for sure that the two Enums I'm trying to use are actually defined within DrawingPrintManager, but I can figure that out once I actually have a DrawingPrintManager to work with
If anyone with more experience in using COM APIs or pywin32 can help me out, I'd be really appreciative. And the same if anyone can point me towards any actual documentation of Inventor's API Objects, which would make things a lot easier.
Thanks
Edit: After posting I've almost immediately found that I can get a PrintManager (can't tell if a PrintManager or DrawingPrintManager) by accessing drawing.PrintManager rather than drawing.DrawingPrintManager.
This is a workaround however as it doesn't answer my question of how to create objects within pywin32.
My problem moving forward is finding where I can access the PrintScaleModeEnum and PrintSizeEnum objects, and finding how to set the save location of the printed PDF (which I think will be a a separate question, as it's probably unrelated to the COM API).
I'm not familiar with python and pywin32, but I try to answer your questions.
Documentation of Inventor API is available in local installation "C:\Users\Public\Documents\Autodesk\Inventor 2020\Local Help" or online https://help.autodesk.com/view/INVNTOR/2020/ENU/
Generaly you are not able to create new instances of Inventor API objects. You must obtain them as a result of appropriate method or property value.
For example:
You CAN'T do this
doc = new Inventor.Document()
You MUST do this
doc = app.Documents.Add(...)
With print manager is this
print_manager = drawing.PrintManger
# this returns object of type Inventor.DrawingPrintManager
# when drawing is of type Inventor.DrawingDocument
See this for more details
I am trying to create a script that would help me automate the creation of a spine rig, but I am running into a problem. I am following the tutorial provided here and I am working on the step where you skin the curve to the IK joints.
However, when I try to use mc.bindSkin(), I keep getting an error:
Error: RuntimeError: file[directory]/maya/2016.5/scripts\createRigSpine.py line 200: Maya command error)
It's too late right now to for me to do much experimenting, but I was hoping someone could help me, or tell me if I'm using the wrong commands.
mc.select(crvSpine, jntIkMidSpine, jntIkChest)
mc.bindSkin(crvSpine, jntIkMidSpine, jntIkChest, tsb=True)
(have also tried mc.bindSkin() and mc.bindSkin(tsb=True))
Ideally, I want the settings to be:
Bind To: Selected Joints
Bind Method: Closest Distance
Skinning Method: Classic Linear
Normalize Weights: Interactive
Edit: I wanted to use skinCluster, not bindSkin.
you should use the skinCluster command to bind your curve to the joints - and you can actually do it without selecting anything!
Try this:
import maya.cmds as mc
influences = [jntIkMidSpine, jntIkChest]
scls = mc.skinCluster(influences, crvSpine, name='spine_skinCluster', toSelectedBones=True, bindMethod=0, skinMethod=0, normalizeWeights=1)[0]
# alternatively, if you don't want such a long line of code:
#
influences = [jntIkMidSpine, jntIkChest]
kwargs = {
'name': 'spine_skinCluster', # or whatever you want to call it...
'toSelectedBones': True,
'bindMethod': 0,
'skinMethod': 0,
'normalizeWeights': 1
}
scls = mc.skinCluster(influences, crvSpine, **kwargs)[0]
# OR just use the short names for the kwargs...
#
influences = [jntIkMidSpine, jntIkChest]
scls = mc.skinCluster(influences, crvSpine, n='spine_skinCluster', tsb=True, bm=0, sm=0, nw=1)[0]
If you wanted to, you could also explicitly set the weights you want for each cv of the curve. You could use the skinPercent command, or even just use setAttr for the various weight attrs in the skinCluster (that's a little more difficult, but not much)
cmds.bindSkin() command made for binding bones to geometry. It's not suitable for binding to IK's only. So you need to assign what joint you need to bind to.
For example:
import maya.cmds as mc
mc.select('ikHandle1','nurbsCircle1','joint5')
mc.bindSkin('ikHandle1','nurbsCircle1','joint5')
# the order of selection is vital
For constraining selected objects use the commands like this:
mc.pointConstraint('ikHandle1','nurbsCircle1', weight=5.0)
To find out what constraints are available to you, use Rigging module – Constrain menu – Parent, Point, Orient, Scale, Aim, Pole Vector.
I was using the wrong command. mc.skinCluster is what I wanted to use, not mc.bindSkin.
I am basically building a 3D scatter plot using primitive UV spheres and am running into memory issues when attempting to create more than a couple hundred points at one time. I am limited on my laptop with a 2.1Ghz processor but wanted to know if there is a better way to write this:
import bpy
import random
while count < 5:
bpy.ops.mesh.primitive_uv_sphere_add(size=.3,\
location=(random.randint(-9,9), random.randint(-9,9),\
random.randint(-9,9)), rotation=(0,0,0))
count += 1
I realize that with such a simple script any performance increase is likely negligible but wanted to give it a shot anyway.
Some possible suggestions
I would pre-calculate the x,y,z values, store them in a mathutil vector and add it to a dict to be iterated over.
Duplication should provide a smaller memory footprint than
instantiating new objects. bpy.ops.object.duplicate_move(OBJECT_OT_duplicate=(linked:false, TRANSFORM_OT_translate=(transform)
Edit:
Doing further research it appears each time a bpy.ops.* is called the redraw function . One user documentented exponential increase in time taken to genenerate UV sphere.
CoDEmanX provided the following code snippet to another user.
import bpy
bpy.ops.object.select_all(action='DESELECT')
bpy.ops.mesh.primitive_uv_sphere_add()
sphere = bpy.context.object
for i in range(-1000, 1000, 2):
ob = sphere.copy()
ob.location.y = i
#ob.data = sphere.data.copy() # uncomment this, if you want full copies and no linked duplicates
bpy.context.scene.objects.link(ob)
bpy.context.scene.update()
Then it is just a case of adapting the code to set the object locations
obj.location = location_dict[i]