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import math
import numpy as np
import dartpy as dart
default_height = 1.0 # m
default_width = 0.2 # m
default_depth = 0.2 # m
default_torque = 15.0 # N-m
default_force = 15.0 # N
default_countdown = 200 # Number of timesteps for applying force
default_rest_position = 0.0
delta_rest_position = 10.0 * math.pi / 180.0
default_stiffness = 0.0
delta_stiffness = 10
default_damping = 5.0
delta_damping = 1.0
def set_geometry(body):
# Create a BoxShape to be used for both visualization and collision checking
box = dart.dynamics.BoxShape([default_width, default_depth, default_height])
# Create a shape node for visualization and collision checking
shape_node = body.createShapeNode(box)
visual = shape_node.createVisualAspect()
shape_node.createCollisionAspect()
shape_node.createDynamicsAspect()
visual.setColor([0, 0, 1])
# Set the location of the shape node
box_tf = dart.math.Isometry3()
center = [0, 0, default_height / 2.0]
box_tf.set_translation(center)
shape_node.setRelativeTransform(box_tf)
# Move the center of mass to the center of the object
body.setLocalCOM(center)
def make_root_body(chain, name):
joint_prop = dart.dynamics.BallJointProperties()
joint_prop.mName = name + '_joint'
joint_prop.mRestPositions = np.ones(3) * default_rest_position
joint_prop.mSpringStiffnesses = np.ones(3) * default_stiffness
joint_prop.mDampingCoefficients = np.ones(3) * default_damping
body_aspect_prop = dart.dynamics.BodyNodeAspectProperties(name)
body_prop = dart.dynamics.BodyNodeProperties(body_aspect_prop)
[joint, body] = chain.createBallJointAndBodyNodePair(None, joint_prop, body_prop)
# Make a shape for the Joint
r = default_width
ball = dart.dynamics.EllipsoidShape(math.sqrt(2) * np.ones(3) * r)
shape_node = body.createShapeNode(ball)
visual = shape_node.createVisualAspect()
visual.setColor([0, 0, 1, 0.8])
# Set the geometry of the BodyNode
set_geometry(body)
return body
def add_body(chain, parent, name):
# Set up the properties for the Joint
joint_prop = dart.dynamics.RevoluteJointProperties()
joint_prop.mName = name + "_joint"
joint_prop.mAxis = [0, 1, 0]
joint_prop.mT_ParentBodyToJoint.set_translation([0, 0, default_height])
# Set up the properties for the BodyNode
body_aspect_prop = dart.dynamics.BodyNodeAspectProperties(name)
body_prop = dart.dynamics.BodyNodeProperties(body_aspect_prop)
# Create a new BodyNode, attached to its parent by a RevoluteJoint
[joint, body] = chain.createRevoluteJointAndBodyNodePair(parent, joint_prop, body_prop)
joint.setRestPosition(0, default_rest_position)
joint.setSpringStiffness(0, default_stiffness)
joint.setDampingCoefficient(0, default_damping)
# Make a shape for the Joint
r = default_width / 2.0
h = default_depth
cylinder = dart.dynamics.CylinderShape(r, h)
# Line up the cylinder with the Joint axis
tf = dart.math.Isometry3()
angles = [math.pi / 2, 0, 0]
rot = dart.math.eulerXYZToMatrix(angles)
tf.set_rotation(rot)
shape_node = body.createShapeNode(cylinder)
visual = shape_node.createVisualAspect()
visual.setColor([0, 0, 1, 0.8])
shape_node.setRelativeTransform(tf)
# Set the geometry of the Body
set_geometry(body)
return body
class MyWorldNode(dart.gui.osg.RealTimeWorldNode):
def __init__(self, world):
super(MyWorldNode, self).__init__(world)
pass
def customPreStep(self):
pass
def main():
# Create an empty Skeleton with the name 'chain'
chain = dart.dynamics.Skeleton('chain')
# Add each body to the last BodyNode in the pendulum
body = make_root_body(chain, 'body1')
body = add_body(chain, body, 'body2')
body = add_body(chain, body, 'body3')
body = add_body(chain, body, 'body4')
body = add_body(chain, body, 'body5')
# Set the initial position of the first DegreeOfFreedom so that the pendulum
# starts to swing right away
chain.setPosition(1, 120 * math.pi / 180.0);
world = dart.simulation.World()
world.addSkeleton(chain)
node = MyWorldNode(world)
# Create world node and add it to viewer
viewer = dart.gui.osg.Viewer()
viewer.addWorldNode(node)
# Grid settings
grid = dart.gui.osg.GridVisual()
grid.setPlaneType(dart.gui.osg.GridVisual.PlaneType.XY)
grid.setOffset([0, 0, -5])
viewer.addAttachment(grid)
viewer.setUpViewInWindow(0, 0, 1280, 760)
viewer.setCameraHomePosition([8.0, 8.0, 4.0], [0, 0, -2.5], [0, 0, 1])
viewer.run()
if __name__ == "__main__":
main()
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