def test_spatial_velocity(self):
velocity = SpatialVelocity()
# - Accessors.
self.assertTrue(isinstance(velocity.rotational(), np.ndarray))
self.assertTrue(isinstance(velocity.translational(), np.ndarray))
self.assertEqual(velocity.rotational().shape, (3,))
self.assertEqual(velocity.translational().shape, (3,))
# - Fully-parameterized constructor.
w = [0.1, 0.3, 0.5]
v = [0., 1., 2.]
velocity1 = SpatialVelocity(w=w, v=v)
self.assertTrue(np.allclose(velocity1.rotational(), w))
self.assertTrue(np.allclose(velocity1.translational(), v))
def test_spatial_velocity(self):
velocity = SpatialVelocity()
# - Accessors.
self.assertTrue(isinstance(velocity.rotational(), np.ndarray))
self.assertTrue(isinstance(velocity.translational(), np.ndarray))
self.assertEqual(velocity.rotational().shape, (3, ))
self.assertEqual(velocity.translational().shape, (3, ))
# - Fully-parameterized constructor.
w = [0.1, 0.3, 0.5]
v = [0., 1., 2.]
velocity1 = SpatialVelocity(w=w, v=v)
self.assertTrue(np.allclose(velocity1.rotational(), w))
self.assertTrue(np.allclose(velocity1.translational(), v))
def test_multibody_tree_kinematics(self):
file_name = FindResourceOrThrow(
"drake/examples/double_pendulum/models/double_pendulum.sdf")
plant = MultibodyPlant()
Parser(plant).AddModelFromFile(file_name)
plant.Finalize()
context = plant.CreateDefaultContext()
world_frame = plant.world_frame()
base = plant.GetBodyByName("base")
base_frame = plant.GetFrameByName("base")
X_WL = plant.CalcRelativeTransform(context,
frame_A=world_frame,
frame_B=base_frame)
self.assertIsInstance(X_WL, Isometry3)
p_AQi = plant.CalcPointsPositions(context=context,
frame_B=base_frame,
p_BQi=np.array([[0, 1, 2],
[10, 11, 12]]).T,
frame_A=world_frame).T
self.assertTupleEqual(p_AQi.shape, (2, 3))
Jv_WL = plant.CalcFrameGeometricJacobianExpressedInWorld(
context=context, frame_B=base_frame, p_BoFo_B=[0, 0, 0])
self.assertTupleEqual(Jv_WL.shape, (6, plant.num_velocities()))
nq = plant.num_positions()
nv = plant.num_velocities()
wrt_list = [
(JacobianWrtVariable.kQDot, nq),
(JacobianWrtVariable.kV, nv),
]
for wrt, nw in wrt_list:
Jw_ABp_E = plant.CalcJacobianSpatialVelocity(context=context,
with_respect_to=wrt,
frame_B=base_frame,
p_BP=np.zeros(3),
frame_A=world_frame,
frame_E=world_frame)
self.assert_sane(Jw_ABp_E)
self.assertEqual(Jw_ABp_E.shape, (6, nw))
# Compute body pose.
X_WBase = plant.EvalBodyPoseInWorld(context, base)
self.assertIsInstance(X_WBase, Isometry3)
# Set pose for the base.
X_WB_desired = Isometry3.Identity()
X_WB = plant.CalcRelativeTransform(context, world_frame, base_frame)
plant.SetFreeBodyPose(context=context, body=base, X_WB=X_WB_desired)
self.assertTrue(np.allclose(X_WB.matrix(), X_WB_desired.matrix()))
# Set a spatial velocity for the base.
v_WB = SpatialVelocity(w=[1, 2, 3], v=[4, 5, 6])
plant.SetFreeBodySpatialVelocity(context=context, body=base, V_WB=v_WB)
v_base = plant.EvalBodySpatialVelocityInWorld(context, base)
self.assertTrue(np.allclose(v_base.rotational(), v_WB.rotational()))
self.assertTrue(
np.allclose(v_base.translational(), v_WB.translational()))
# Compute accelerations.
vdot = np.zeros(nv)
A_WB_array = plant.CalcSpatialAccelerationsFromVdot(context=context,
known_vdot=vdot)
self.assertEqual(len(A_WB_array), plant.num_bodies())
def test_multibody_tree_kinematics(self):
file_name = FindResourceOrThrow(
"drake/examples/double_pendulum/models/double_pendulum.sdf")
plant = MultibodyPlant()
Parser(plant).AddModelFromFile(file_name)
plant.Finalize()
context = plant.CreateDefaultContext()
world_frame = plant.world_frame()
base = plant.GetBodyByName("base")
base_frame = plant.GetFrameByName("base")
X_WL = plant.CalcRelativeTransform(
context, frame_A=world_frame, frame_B=base_frame)
self.assertIsInstance(X_WL, Isometry3)
p_AQi = plant.CalcPointsPositions(
context=context, frame_B=base_frame,
p_BQi=np.array([[0, 1, 2], [10, 11, 12]]).T,
frame_A=world_frame).T
self.assertTupleEqual(p_AQi.shape, (2, 3))
Jv_WL = plant.CalcFrameGeometricJacobianExpressedInWorld(
context=context, frame_B=base_frame,
p_BoFo_B=[0, 0, 0])
self.assertTupleEqual(Jv_WL.shape, (6, plant.num_velocities()))
nq = plant.num_positions()
nv = plant.num_velocities()
wrt_list = [
(JacobianWrtVariable.kQDot, nq),
(JacobianWrtVariable.kV, nv),
]
for wrt, nw in wrt_list:
Jw_ABp_E = plant.CalcJacobianSpatialVelocity(
context=context, with_respect_to=wrt, frame_B=base_frame,
p_BP=np.zeros(3), frame_A=world_frame,
frame_E=world_frame)
self.assert_sane(Jw_ABp_E)
self.assertEqual(Jw_ABp_E.shape, (6, nw))
# Compute body pose.
X_WBase = plant.EvalBodyPoseInWorld(context, base)
self.assertIsInstance(X_WBase, Isometry3)
# Set pose for the base.
X_WB_desired = Isometry3.Identity()
X_WB = plant.CalcRelativeTransform(context, world_frame, base_frame)
plant.SetFreeBodyPose(
context=context, body=base, X_WB=X_WB_desired)
self.assertTrue(np.allclose(X_WB.matrix(), X_WB_desired.matrix()))
# Set a spatial velocity for the base.
v_WB = SpatialVelocity(w=[1, 2, 3], v=[4, 5, 6])
plant.SetFreeBodySpatialVelocity(
context=context, body=base, V_WB=v_WB)
v_base = plant.EvalBodySpatialVelocityInWorld(context, base)
self.assertTrue(np.allclose(v_base.rotational(), v_WB.rotational()))
self.assertTrue(np.allclose(v_base.translational(),
v_WB.translational()))
# Compute accelerations.
vdot = np.zeros(nv)
A_WB_array = plant.CalcSpatialAccelerationsFromVdot(
context=context, known_vdot=vdot)
self.assertEqual(len(A_WB_array), plant.num_bodies())
def test_multibody_tree_kinematics(self):
file_name = FindResourceOrThrow(
"drake/examples/double_pendulum/models/double_pendulum.sdf")
plant = MultibodyPlant()
AddModelFromSdfFile(file_name, plant)
plant.Finalize()
context = plant.CreateDefaultContext()
tree = plant.tree()
world_frame = plant.world_frame()
base = plant.GetBodyByName("base")
base_frame = plant.GetFrameByName("base")
X_WL = tree.CalcRelativeTransform(
context, frame_A=world_frame, frame_B=base_frame)
self.assertIsInstance(X_WL, Isometry3)
p_AQi = tree.CalcPointsPositions(
context=context, frame_B=base_frame,
p_BQi=np.array([[0, 1, 2], [10, 11, 12]]).T,
frame_A=world_frame).T
self.assertTupleEqual(p_AQi.shape, (2, 3))
Jv_WL = tree.CalcFrameGeometricJacobianExpressedInWorld(
context=context, frame_B=base_frame,
p_BoFo_B=[0, 0, 0])
self.assertTupleEqual(Jv_WL.shape, (6, plant.num_velocities()))
# Compute body pose.
X_WBase = tree.EvalBodyPoseInWorld(context, base)
self.assertIsInstance(X_WBase, Isometry3)
# All body poses.
X_WB_list = tree.CalcAllBodyPosesInWorld(context)
self.assertEqual(len(X_WB_list), 4)
for X_WB in X_WB_list:
self.assertIsInstance(X_WB, Isometry3)
# Compute body velocities.
v_WB_list = tree.CalcAllBodySpatialVelocitiesInWorld(context)
self.assertEqual(len(v_WB_list), 4)
for v_WB in v_WB_list:
self.assertIsInstance(v_WB, SpatialVelocity)
# - Sanity check.
v_WBase_flat = np.hstack((
v_WB_list[0].rotational(), v_WB_list[0].translational()))
self.assertTrue(np.allclose(v_WBase_flat, np.zeros(6)))
# Set pose for the base.
X_WB_desired = Isometry3.Identity()
X_WB = tree.CalcRelativeTransform(context, world_frame, base_frame)
tree.SetFreeBodyPoseOrThrow(
body=base, X_WB=X_WB_desired, context=context)
self.assertTrue(np.allclose(X_WB.matrix(), X_WB_desired.matrix()))
# Set a spatial velocity for the base.
v_WB = SpatialVelocity(w=[1, 2, 3], v=[4, 5, 6])
tree.SetFreeBodySpatialVelocityOrThrow(
body=base, V_WB=v_WB, context=context)
v_base = tree.EvalBodySpatialVelocityInWorld(context, base)
self.assertTrue(np.allclose(v_base.rotational(), v_WB.rotational()))
self.assertTrue(np.allclose(v_base.translational(),
v_WB.translational()))
def test_multibody_tree_kinematics(self):
file_name = FindResourceOrThrow(
"drake/examples/double_pendulum/models/double_pendulum.sdf")
plant = MultibodyPlant()
AddModelFromSdfFile(file_name, plant)
plant.Finalize()
context = plant.CreateDefaultContext()
tree = plant.tree()
world_frame = plant.world_frame()
base = plant.GetBodyByName("base")
base_frame = plant.GetFrameByName("base")
X_WL = tree.CalcRelativeTransform(context,
frame_A=world_frame,
frame_B=base_frame)
self.assertIsInstance(X_WL, Isometry3)
p_AQi = tree.CalcPointsPositions(context=context,
frame_B=base_frame,
p_BQi=np.array([[0, 1, 2],
[10, 11, 12]]).T,
frame_A=world_frame).T
self.assertTupleEqual(p_AQi.shape, (2, 3))
Jv_WL = tree.CalcFrameGeometricJacobianExpressedInWorld(
context=context, frame_B=base_frame, p_BoFo_B=[0, 0, 0])
self.assertTupleEqual(Jv_WL.shape, (6, plant.num_velocities()))
# Compute body pose.
X_WBase = tree.EvalBodyPoseInWorld(context, base)
self.assertIsInstance(X_WBase, Isometry3)
# All body poses.
X_WB_list = tree.CalcAllBodyPosesInWorld(context)
self.assertEqual(len(X_WB_list), 4)
for X_WB in X_WB_list:
self.assertIsInstance(X_WB, Isometry3)
# Compute body velocities.
v_WB_list = tree.CalcAllBodySpatialVelocitiesInWorld(context)
self.assertEqual(len(v_WB_list), 4)
for v_WB in v_WB_list:
self.assertIsInstance(v_WB, SpatialVelocity)
# - Sanity check.
v_WBase_flat = np.hstack(
(v_WB_list[0].rotational(), v_WB_list[0].translational()))
self.assertTrue(np.allclose(v_WBase_flat, np.zeros(6)))
# Set pose for the base.
X_WB_desired = Isometry3.Identity()
X_WB = tree.CalcRelativeTransform(context, world_frame, base_frame)
tree.SetFreeBodyPoseOrThrow(body=base,
X_WB=X_WB_desired,
context=context)
self.assertTrue(np.allclose(X_WB.matrix(), X_WB_desired.matrix()))
# Set a spatial velocity for the base.
v_WB = SpatialVelocity(w=[1, 2, 3], v=[4, 5, 6])
tree.SetFreeBodySpatialVelocityOrThrow(body=base,
V_WB=v_WB,
context=context)
v_base = tree.EvalBodySpatialVelocityInWorld(context, base)
self.assertTrue(np.allclose(v_base.rotational(), v_WB.rotational()))
self.assertTrue(
np.allclose(v_base.translational(), v_WB.translational()))