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import numpy as np
import dartpy as dart
class HelloWorldNode(dart.gui.osg.RealTimeWorldNode):
def __init__(self, world, kr5):
super(HelloWorldNode, self).__init__(world)
self.kr5 = kr5
self.dofs = self.kr5.getNumDofs()
self.ee = kr5.getBodyNode('palm')
self.Kp = np.eye(3) * 50.0
self.Kd = np.eye(self.dofs) * 5.0
self.ee_offset = [0.05, 0, 0]
tf = self.ee.getTransform()
tf.pretranslate(self.ee_offset)
self.target = dart.dynamics.SimpleFrame(dart.dynamics.Frame.World(), "target", tf)
def customPreStep(self):
M = self.kr5.getMassMatrix()
J = self.ee.getLinearJacobian()
Jt = J.transpose();
JJt = np.matmul(J, Jt)
kI = 0.0025 * np.eye(3)
invJ = np.matmul(Jt, np.linalg.inv(JJt + kI))
dJ = self.ee.getLinearJacobianDeriv()
dJt = dJ.transpose()
dJdJt = np.matmul(dJ, dJt)
invdJ = np.matmul(dJt, np.linalg.inv(dJdJt + kI))
e = self.target.getTransform().translation() - self.ee.getTransform().translation()
de = -self.ee.getLinearVelocity()
cg = self.kr5.getCoriolisAndGravityForces()
tmp1 = np.matmul(np.matmul(invJ, self.Kp), de)
tmp2 = np.matmul(np.matmul(invdJ, self.Kp), e)
forces1 = np.matmul(M, tmp1 + tmp2)
forces2 = cg
forces3 = np.matmul(np.matmul(np.matmul(self.Kd, invJ), self.Kp), e)
forces = forces1 + forces2 + forces3
self.kr5.setForces(forces)
def main():
world = dart.simulation.World()
urdfParser = dart.utils.DartLoader()
kr5 = urdfParser.parseSkeleton("dart://sample/urdf/KR5/KR5 sixx R650.urdf")
ground = urdfParser.parseSkeleton("dart://sample/urdf/KR5/ground.urdf")
world.addSkeleton(kr5)
world.addSkeleton(ground)
world.setGravity([0, -9.81, 0])
node = HelloWorldNode(world, kr5)
# 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.ZX)
grid.setOffset([0, -0.55, 0])
viewer.addAttachment(grid)
viewer.setUpViewInWindow(0, 0, 640, 480)
viewer.setCameraHomePosition([2.0, 1.0, 2.0],
[0.00, 0.00, 0.00],
[-0.24, 0.94, -0.25])
viewer.run()
if __name__ == "__main__":
main()
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